cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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core.c (289348B)


      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 *  kernel/sched/core.c
      4 *
      5 *  Core kernel scheduler code and related syscalls
      6 *
      7 *  Copyright (C) 1991-2002  Linus Torvalds
      8 */
      9#include <linux/highmem.h>
     10#include <linux/hrtimer_api.h>
     11#include <linux/ktime_api.h>
     12#include <linux/sched/signal.h>
     13#include <linux/syscalls_api.h>
     14#include <linux/debug_locks.h>
     15#include <linux/prefetch.h>
     16#include <linux/capability.h>
     17#include <linux/pgtable_api.h>
     18#include <linux/wait_bit.h>
     19#include <linux/jiffies.h>
     20#include <linux/spinlock_api.h>
     21#include <linux/cpumask_api.h>
     22#include <linux/lockdep_api.h>
     23#include <linux/hardirq.h>
     24#include <linux/softirq.h>
     25#include <linux/refcount_api.h>
     26#include <linux/topology.h>
     27#include <linux/sched/clock.h>
     28#include <linux/sched/cond_resched.h>
     29#include <linux/sched/cputime.h>
     30#include <linux/sched/debug.h>
     31#include <linux/sched/hotplug.h>
     32#include <linux/sched/init.h>
     33#include <linux/sched/isolation.h>
     34#include <linux/sched/loadavg.h>
     35#include <linux/sched/mm.h>
     36#include <linux/sched/nohz.h>
     37#include <linux/sched/rseq_api.h>
     38#include <linux/sched/rt.h>
     39
     40#include <linux/blkdev.h>
     41#include <linux/context_tracking.h>
     42#include <linux/cpuset.h>
     43#include <linux/delayacct.h>
     44#include <linux/init_task.h>
     45#include <linux/interrupt.h>
     46#include <linux/ioprio.h>
     47#include <linux/kallsyms.h>
     48#include <linux/kcov.h>
     49#include <linux/kprobes.h>
     50#include <linux/llist_api.h>
     51#include <linux/mmu_context.h>
     52#include <linux/mmzone.h>
     53#include <linux/mutex_api.h>
     54#include <linux/nmi.h>
     55#include <linux/nospec.h>
     56#include <linux/perf_event_api.h>
     57#include <linux/profile.h>
     58#include <linux/psi.h>
     59#include <linux/rcuwait_api.h>
     60#include <linux/sched/wake_q.h>
     61#include <linux/scs.h>
     62#include <linux/slab.h>
     63#include <linux/syscalls.h>
     64#include <linux/vtime.h>
     65#include <linux/wait_api.h>
     66#include <linux/workqueue_api.h>
     67
     68#ifdef CONFIG_PREEMPT_DYNAMIC
     69# ifdef CONFIG_GENERIC_ENTRY
     70#  include <linux/entry-common.h>
     71# endif
     72#endif
     73
     74#include <uapi/linux/sched/types.h>
     75
     76#include <asm/switch_to.h>
     77#include <asm/tlb.h>
     78
     79#define CREATE_TRACE_POINTS
     80#include <linux/sched/rseq_api.h>
     81#include <trace/events/sched.h>
     82#undef CREATE_TRACE_POINTS
     83
     84#include "sched.h"
     85#include "stats.h"
     86#include "autogroup.h"
     87
     88#include "autogroup.h"
     89#include "pelt.h"
     90#include "smp.h"
     91#include "stats.h"
     92
     93#include "../workqueue_internal.h"
     94#include "../../fs/io-wq.h"
     95#include "../smpboot.h"
     96
     97/*
     98 * Export tracepoints that act as a bare tracehook (ie: have no trace event
     99 * associated with them) to allow external modules to probe them.
    100 */
    101EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_cfs_tp);
    102EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_rt_tp);
    103EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_dl_tp);
    104EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_irq_tp);
    105EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_se_tp);
    106EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_thermal_tp);
    107EXPORT_TRACEPOINT_SYMBOL_GPL(sched_cpu_capacity_tp);
    108EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp);
    109EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_cfs_tp);
    110EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_se_tp);
    111EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp);
    112
    113DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
    114
    115#ifdef CONFIG_SCHED_DEBUG
    116/*
    117 * Debugging: various feature bits
    118 *
    119 * If SCHED_DEBUG is disabled, each compilation unit has its own copy of
    120 * sysctl_sched_features, defined in sched.h, to allow constants propagation
    121 * at compile time and compiler optimization based on features default.
    122 */
    123#define SCHED_FEAT(name, enabled)	\
    124	(1UL << __SCHED_FEAT_##name) * enabled |
    125const_debug unsigned int sysctl_sched_features =
    126#include "features.h"
    127	0;
    128#undef SCHED_FEAT
    129
    130/*
    131 * Print a warning if need_resched is set for the given duration (if
    132 * LATENCY_WARN is enabled).
    133 *
    134 * If sysctl_resched_latency_warn_once is set, only one warning will be shown
    135 * per boot.
    136 */
    137__read_mostly int sysctl_resched_latency_warn_ms = 100;
    138__read_mostly int sysctl_resched_latency_warn_once = 1;
    139#endif /* CONFIG_SCHED_DEBUG */
    140
    141/*
    142 * Number of tasks to iterate in a single balance run.
    143 * Limited because this is done with IRQs disabled.
    144 */
    145#ifdef CONFIG_PREEMPT_RT
    146const_debug unsigned int sysctl_sched_nr_migrate = 8;
    147#else
    148const_debug unsigned int sysctl_sched_nr_migrate = 32;
    149#endif
    150
    151__read_mostly int scheduler_running;
    152
    153#ifdef CONFIG_SCHED_CORE
    154
    155DEFINE_STATIC_KEY_FALSE(__sched_core_enabled);
    156
    157/* kernel prio, less is more */
    158static inline int __task_prio(struct task_struct *p)
    159{
    160	if (p->sched_class == &stop_sched_class) /* trumps deadline */
    161		return -2;
    162
    163	if (rt_prio(p->prio)) /* includes deadline */
    164		return p->prio; /* [-1, 99] */
    165
    166	if (p->sched_class == &idle_sched_class)
    167		return MAX_RT_PRIO + NICE_WIDTH; /* 140 */
    168
    169	return MAX_RT_PRIO + MAX_NICE; /* 120, squash fair */
    170}
    171
    172/*
    173 * l(a,b)
    174 * le(a,b) := !l(b,a)
    175 * g(a,b)  := l(b,a)
    176 * ge(a,b) := !l(a,b)
    177 */
    178
    179/* real prio, less is less */
    180static inline bool prio_less(struct task_struct *a, struct task_struct *b, bool in_fi)
    181{
    182
    183	int pa = __task_prio(a), pb = __task_prio(b);
    184
    185	if (-pa < -pb)
    186		return true;
    187
    188	if (-pb < -pa)
    189		return false;
    190
    191	if (pa == -1) /* dl_prio() doesn't work because of stop_class above */
    192		return !dl_time_before(a->dl.deadline, b->dl.deadline);
    193
    194	if (pa == MAX_RT_PRIO + MAX_NICE)	/* fair */
    195		return cfs_prio_less(a, b, in_fi);
    196
    197	return false;
    198}
    199
    200static inline bool __sched_core_less(struct task_struct *a, struct task_struct *b)
    201{
    202	if (a->core_cookie < b->core_cookie)
    203		return true;
    204
    205	if (a->core_cookie > b->core_cookie)
    206		return false;
    207
    208	/* flip prio, so high prio is leftmost */
    209	if (prio_less(b, a, !!task_rq(a)->core->core_forceidle_count))
    210		return true;
    211
    212	return false;
    213}
    214
    215#define __node_2_sc(node) rb_entry((node), struct task_struct, core_node)
    216
    217static inline bool rb_sched_core_less(struct rb_node *a, const struct rb_node *b)
    218{
    219	return __sched_core_less(__node_2_sc(a), __node_2_sc(b));
    220}
    221
    222static inline int rb_sched_core_cmp(const void *key, const struct rb_node *node)
    223{
    224	const struct task_struct *p = __node_2_sc(node);
    225	unsigned long cookie = (unsigned long)key;
    226
    227	if (cookie < p->core_cookie)
    228		return -1;
    229
    230	if (cookie > p->core_cookie)
    231		return 1;
    232
    233	return 0;
    234}
    235
    236void sched_core_enqueue(struct rq *rq, struct task_struct *p)
    237{
    238	rq->core->core_task_seq++;
    239
    240	if (!p->core_cookie)
    241		return;
    242
    243	rb_add(&p->core_node, &rq->core_tree, rb_sched_core_less);
    244}
    245
    246void sched_core_dequeue(struct rq *rq, struct task_struct *p, int flags)
    247{
    248	rq->core->core_task_seq++;
    249
    250	if (sched_core_enqueued(p)) {
    251		rb_erase(&p->core_node, &rq->core_tree);
    252		RB_CLEAR_NODE(&p->core_node);
    253	}
    254
    255	/*
    256	 * Migrating the last task off the cpu, with the cpu in forced idle
    257	 * state. Reschedule to create an accounting edge for forced idle,
    258	 * and re-examine whether the core is still in forced idle state.
    259	 */
    260	if (!(flags & DEQUEUE_SAVE) && rq->nr_running == 1 &&
    261	    rq->core->core_forceidle_count && rq->curr == rq->idle)
    262		resched_curr(rq);
    263}
    264
    265/*
    266 * Find left-most (aka, highest priority) task matching @cookie.
    267 */
    268static struct task_struct *sched_core_find(struct rq *rq, unsigned long cookie)
    269{
    270	struct rb_node *node;
    271
    272	node = rb_find_first((void *)cookie, &rq->core_tree, rb_sched_core_cmp);
    273	/*
    274	 * The idle task always matches any cookie!
    275	 */
    276	if (!node)
    277		return idle_sched_class.pick_task(rq);
    278
    279	return __node_2_sc(node);
    280}
    281
    282static struct task_struct *sched_core_next(struct task_struct *p, unsigned long cookie)
    283{
    284	struct rb_node *node = &p->core_node;
    285
    286	node = rb_next(node);
    287	if (!node)
    288		return NULL;
    289
    290	p = container_of(node, struct task_struct, core_node);
    291	if (p->core_cookie != cookie)
    292		return NULL;
    293
    294	return p;
    295}
    296
    297/*
    298 * Magic required such that:
    299 *
    300 *	raw_spin_rq_lock(rq);
    301 *	...
    302 *	raw_spin_rq_unlock(rq);
    303 *
    304 * ends up locking and unlocking the _same_ lock, and all CPUs
    305 * always agree on what rq has what lock.
    306 *
    307 * XXX entirely possible to selectively enable cores, don't bother for now.
    308 */
    309
    310static DEFINE_MUTEX(sched_core_mutex);
    311static atomic_t sched_core_count;
    312static struct cpumask sched_core_mask;
    313
    314static void sched_core_lock(int cpu, unsigned long *flags)
    315{
    316	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
    317	int t, i = 0;
    318
    319	local_irq_save(*flags);
    320	for_each_cpu(t, smt_mask)
    321		raw_spin_lock_nested(&cpu_rq(t)->__lock, i++);
    322}
    323
    324static void sched_core_unlock(int cpu, unsigned long *flags)
    325{
    326	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
    327	int t;
    328
    329	for_each_cpu(t, smt_mask)
    330		raw_spin_unlock(&cpu_rq(t)->__lock);
    331	local_irq_restore(*flags);
    332}
    333
    334static void __sched_core_flip(bool enabled)
    335{
    336	unsigned long flags;
    337	int cpu, t;
    338
    339	cpus_read_lock();
    340
    341	/*
    342	 * Toggle the online cores, one by one.
    343	 */
    344	cpumask_copy(&sched_core_mask, cpu_online_mask);
    345	for_each_cpu(cpu, &sched_core_mask) {
    346		const struct cpumask *smt_mask = cpu_smt_mask(cpu);
    347
    348		sched_core_lock(cpu, &flags);
    349
    350		for_each_cpu(t, smt_mask)
    351			cpu_rq(t)->core_enabled = enabled;
    352
    353		cpu_rq(cpu)->core->core_forceidle_start = 0;
    354
    355		sched_core_unlock(cpu, &flags);
    356
    357		cpumask_andnot(&sched_core_mask, &sched_core_mask, smt_mask);
    358	}
    359
    360	/*
    361	 * Toggle the offline CPUs.
    362	 */
    363	cpumask_copy(&sched_core_mask, cpu_possible_mask);
    364	cpumask_andnot(&sched_core_mask, &sched_core_mask, cpu_online_mask);
    365
    366	for_each_cpu(cpu, &sched_core_mask)
    367		cpu_rq(cpu)->core_enabled = enabled;
    368
    369	cpus_read_unlock();
    370}
    371
    372static void sched_core_assert_empty(void)
    373{
    374	int cpu;
    375
    376	for_each_possible_cpu(cpu)
    377		WARN_ON_ONCE(!RB_EMPTY_ROOT(&cpu_rq(cpu)->core_tree));
    378}
    379
    380static void __sched_core_enable(void)
    381{
    382	static_branch_enable(&__sched_core_enabled);
    383	/*
    384	 * Ensure all previous instances of raw_spin_rq_*lock() have finished
    385	 * and future ones will observe !sched_core_disabled().
    386	 */
    387	synchronize_rcu();
    388	__sched_core_flip(true);
    389	sched_core_assert_empty();
    390}
    391
    392static void __sched_core_disable(void)
    393{
    394	sched_core_assert_empty();
    395	__sched_core_flip(false);
    396	static_branch_disable(&__sched_core_enabled);
    397}
    398
    399void sched_core_get(void)
    400{
    401	if (atomic_inc_not_zero(&sched_core_count))
    402		return;
    403
    404	mutex_lock(&sched_core_mutex);
    405	if (!atomic_read(&sched_core_count))
    406		__sched_core_enable();
    407
    408	smp_mb__before_atomic();
    409	atomic_inc(&sched_core_count);
    410	mutex_unlock(&sched_core_mutex);
    411}
    412
    413static void __sched_core_put(struct work_struct *work)
    414{
    415	if (atomic_dec_and_mutex_lock(&sched_core_count, &sched_core_mutex)) {
    416		__sched_core_disable();
    417		mutex_unlock(&sched_core_mutex);
    418	}
    419}
    420
    421void sched_core_put(void)
    422{
    423	static DECLARE_WORK(_work, __sched_core_put);
    424
    425	/*
    426	 * "There can be only one"
    427	 *
    428	 * Either this is the last one, or we don't actually need to do any
    429	 * 'work'. If it is the last *again*, we rely on
    430	 * WORK_STRUCT_PENDING_BIT.
    431	 */
    432	if (!atomic_add_unless(&sched_core_count, -1, 1))
    433		schedule_work(&_work);
    434}
    435
    436#else /* !CONFIG_SCHED_CORE */
    437
    438static inline void sched_core_enqueue(struct rq *rq, struct task_struct *p) { }
    439static inline void
    440sched_core_dequeue(struct rq *rq, struct task_struct *p, int flags) { }
    441
    442#endif /* CONFIG_SCHED_CORE */
    443
    444/*
    445 * Serialization rules:
    446 *
    447 * Lock order:
    448 *
    449 *   p->pi_lock
    450 *     rq->lock
    451 *       hrtimer_cpu_base->lock (hrtimer_start() for bandwidth controls)
    452 *
    453 *  rq1->lock
    454 *    rq2->lock  where: rq1 < rq2
    455 *
    456 * Regular state:
    457 *
    458 * Normal scheduling state is serialized by rq->lock. __schedule() takes the
    459 * local CPU's rq->lock, it optionally removes the task from the runqueue and
    460 * always looks at the local rq data structures to find the most eligible task
    461 * to run next.
    462 *
    463 * Task enqueue is also under rq->lock, possibly taken from another CPU.
    464 * Wakeups from another LLC domain might use an IPI to transfer the enqueue to
    465 * the local CPU to avoid bouncing the runqueue state around [ see
    466 * ttwu_queue_wakelist() ]
    467 *
    468 * Task wakeup, specifically wakeups that involve migration, are horribly
    469 * complicated to avoid having to take two rq->locks.
    470 *
    471 * Special state:
    472 *
    473 * System-calls and anything external will use task_rq_lock() which acquires
    474 * both p->pi_lock and rq->lock. As a consequence the state they change is
    475 * stable while holding either lock:
    476 *
    477 *  - sched_setaffinity()/
    478 *    set_cpus_allowed_ptr():	p->cpus_ptr, p->nr_cpus_allowed
    479 *  - set_user_nice():		p->se.load, p->*prio
    480 *  - __sched_setscheduler():	p->sched_class, p->policy, p->*prio,
    481 *				p->se.load, p->rt_priority,
    482 *				p->dl.dl_{runtime, deadline, period, flags, bw, density}
    483 *  - sched_setnuma():		p->numa_preferred_nid
    484 *  - sched_move_task()/
    485 *    cpu_cgroup_fork():	p->sched_task_group
    486 *  - uclamp_update_active()	p->uclamp*
    487 *
    488 * p->state <- TASK_*:
    489 *
    490 *   is changed locklessly using set_current_state(), __set_current_state() or
    491 *   set_special_state(), see their respective comments, or by
    492 *   try_to_wake_up(). This latter uses p->pi_lock to serialize against
    493 *   concurrent self.
    494 *
    495 * p->on_rq <- { 0, 1 = TASK_ON_RQ_QUEUED, 2 = TASK_ON_RQ_MIGRATING }:
    496 *
    497 *   is set by activate_task() and cleared by deactivate_task(), under
    498 *   rq->lock. Non-zero indicates the task is runnable, the special
    499 *   ON_RQ_MIGRATING state is used for migration without holding both
    500 *   rq->locks. It indicates task_cpu() is not stable, see task_rq_lock().
    501 *
    502 * p->on_cpu <- { 0, 1 }:
    503 *
    504 *   is set by prepare_task() and cleared by finish_task() such that it will be
    505 *   set before p is scheduled-in and cleared after p is scheduled-out, both
    506 *   under rq->lock. Non-zero indicates the task is running on its CPU.
    507 *
    508 *   [ The astute reader will observe that it is possible for two tasks on one
    509 *     CPU to have ->on_cpu = 1 at the same time. ]
    510 *
    511 * task_cpu(p): is changed by set_task_cpu(), the rules are:
    512 *
    513 *  - Don't call set_task_cpu() on a blocked task:
    514 *
    515 *    We don't care what CPU we're not running on, this simplifies hotplug,
    516 *    the CPU assignment of blocked tasks isn't required to be valid.
    517 *
    518 *  - for try_to_wake_up(), called under p->pi_lock:
    519 *
    520 *    This allows try_to_wake_up() to only take one rq->lock, see its comment.
    521 *
    522 *  - for migration called under rq->lock:
    523 *    [ see task_on_rq_migrating() in task_rq_lock() ]
    524 *
    525 *    o move_queued_task()
    526 *    o detach_task()
    527 *
    528 *  - for migration called under double_rq_lock():
    529 *
    530 *    o __migrate_swap_task()
    531 *    o push_rt_task() / pull_rt_task()
    532 *    o push_dl_task() / pull_dl_task()
    533 *    o dl_task_offline_migration()
    534 *
    535 */
    536
    537void raw_spin_rq_lock_nested(struct rq *rq, int subclass)
    538{
    539	raw_spinlock_t *lock;
    540
    541	/* Matches synchronize_rcu() in __sched_core_enable() */
    542	preempt_disable();
    543	if (sched_core_disabled()) {
    544		raw_spin_lock_nested(&rq->__lock, subclass);
    545		/* preempt_count *MUST* be > 1 */
    546		preempt_enable_no_resched();
    547		return;
    548	}
    549
    550	for (;;) {
    551		lock = __rq_lockp(rq);
    552		raw_spin_lock_nested(lock, subclass);
    553		if (likely(lock == __rq_lockp(rq))) {
    554			/* preempt_count *MUST* be > 1 */
    555			preempt_enable_no_resched();
    556			return;
    557		}
    558		raw_spin_unlock(lock);
    559	}
    560}
    561
    562bool raw_spin_rq_trylock(struct rq *rq)
    563{
    564	raw_spinlock_t *lock;
    565	bool ret;
    566
    567	/* Matches synchronize_rcu() in __sched_core_enable() */
    568	preempt_disable();
    569	if (sched_core_disabled()) {
    570		ret = raw_spin_trylock(&rq->__lock);
    571		preempt_enable();
    572		return ret;
    573	}
    574
    575	for (;;) {
    576		lock = __rq_lockp(rq);
    577		ret = raw_spin_trylock(lock);
    578		if (!ret || (likely(lock == __rq_lockp(rq)))) {
    579			preempt_enable();
    580			return ret;
    581		}
    582		raw_spin_unlock(lock);
    583	}
    584}
    585
    586void raw_spin_rq_unlock(struct rq *rq)
    587{
    588	raw_spin_unlock(rq_lockp(rq));
    589}
    590
    591#ifdef CONFIG_SMP
    592/*
    593 * double_rq_lock - safely lock two runqueues
    594 */
    595void double_rq_lock(struct rq *rq1, struct rq *rq2)
    596{
    597	lockdep_assert_irqs_disabled();
    598
    599	if (rq_order_less(rq2, rq1))
    600		swap(rq1, rq2);
    601
    602	raw_spin_rq_lock(rq1);
    603	if (__rq_lockp(rq1) != __rq_lockp(rq2))
    604		raw_spin_rq_lock_nested(rq2, SINGLE_DEPTH_NESTING);
    605
    606	double_rq_clock_clear_update(rq1, rq2);
    607}
    608#endif
    609
    610/*
    611 * __task_rq_lock - lock the rq @p resides on.
    612 */
    613struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
    614	__acquires(rq->lock)
    615{
    616	struct rq *rq;
    617
    618	lockdep_assert_held(&p->pi_lock);
    619
    620	for (;;) {
    621		rq = task_rq(p);
    622		raw_spin_rq_lock(rq);
    623		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
    624			rq_pin_lock(rq, rf);
    625			return rq;
    626		}
    627		raw_spin_rq_unlock(rq);
    628
    629		while (unlikely(task_on_rq_migrating(p)))
    630			cpu_relax();
    631	}
    632}
    633
    634/*
    635 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
    636 */
    637struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
    638	__acquires(p->pi_lock)
    639	__acquires(rq->lock)
    640{
    641	struct rq *rq;
    642
    643	for (;;) {
    644		raw_spin_lock_irqsave(&p->pi_lock, rf->flags);
    645		rq = task_rq(p);
    646		raw_spin_rq_lock(rq);
    647		/*
    648		 *	move_queued_task()		task_rq_lock()
    649		 *
    650		 *	ACQUIRE (rq->lock)
    651		 *	[S] ->on_rq = MIGRATING		[L] rq = task_rq()
    652		 *	WMB (__set_task_cpu())		ACQUIRE (rq->lock);
    653		 *	[S] ->cpu = new_cpu		[L] task_rq()
    654		 *					[L] ->on_rq
    655		 *	RELEASE (rq->lock)
    656		 *
    657		 * If we observe the old CPU in task_rq_lock(), the acquire of
    658		 * the old rq->lock will fully serialize against the stores.
    659		 *
    660		 * If we observe the new CPU in task_rq_lock(), the address
    661		 * dependency headed by '[L] rq = task_rq()' and the acquire
    662		 * will pair with the WMB to ensure we then also see migrating.
    663		 */
    664		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
    665			rq_pin_lock(rq, rf);
    666			return rq;
    667		}
    668		raw_spin_rq_unlock(rq);
    669		raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
    670
    671		while (unlikely(task_on_rq_migrating(p)))
    672			cpu_relax();
    673	}
    674}
    675
    676/*
    677 * RQ-clock updating methods:
    678 */
    679
    680static void update_rq_clock_task(struct rq *rq, s64 delta)
    681{
    682/*
    683 * In theory, the compile should just see 0 here, and optimize out the call
    684 * to sched_rt_avg_update. But I don't trust it...
    685 */
    686	s64 __maybe_unused steal = 0, irq_delta = 0;
    687
    688#ifdef CONFIG_IRQ_TIME_ACCOUNTING
    689	irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
    690
    691	/*
    692	 * Since irq_time is only updated on {soft,}irq_exit, we might run into
    693	 * this case when a previous update_rq_clock() happened inside a
    694	 * {soft,}irq region.
    695	 *
    696	 * When this happens, we stop ->clock_task and only update the
    697	 * prev_irq_time stamp to account for the part that fit, so that a next
    698	 * update will consume the rest. This ensures ->clock_task is
    699	 * monotonic.
    700	 *
    701	 * It does however cause some slight miss-attribution of {soft,}irq
    702	 * time, a more accurate solution would be to update the irq_time using
    703	 * the current rq->clock timestamp, except that would require using
    704	 * atomic ops.
    705	 */
    706	if (irq_delta > delta)
    707		irq_delta = delta;
    708
    709	rq->prev_irq_time += irq_delta;
    710	delta -= irq_delta;
    711#endif
    712#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
    713	if (static_key_false((&paravirt_steal_rq_enabled))) {
    714		steal = paravirt_steal_clock(cpu_of(rq));
    715		steal -= rq->prev_steal_time_rq;
    716
    717		if (unlikely(steal > delta))
    718			steal = delta;
    719
    720		rq->prev_steal_time_rq += steal;
    721		delta -= steal;
    722	}
    723#endif
    724
    725	rq->clock_task += delta;
    726
    727#ifdef CONFIG_HAVE_SCHED_AVG_IRQ
    728	if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
    729		update_irq_load_avg(rq, irq_delta + steal);
    730#endif
    731	update_rq_clock_pelt(rq, delta);
    732}
    733
    734void update_rq_clock(struct rq *rq)
    735{
    736	s64 delta;
    737
    738	lockdep_assert_rq_held(rq);
    739
    740	if (rq->clock_update_flags & RQCF_ACT_SKIP)
    741		return;
    742
    743#ifdef CONFIG_SCHED_DEBUG
    744	if (sched_feat(WARN_DOUBLE_CLOCK))
    745		SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED);
    746	rq->clock_update_flags |= RQCF_UPDATED;
    747#endif
    748
    749	delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
    750	if (delta < 0)
    751		return;
    752	rq->clock += delta;
    753	update_rq_clock_task(rq, delta);
    754}
    755
    756#ifdef CONFIG_SCHED_HRTICK
    757/*
    758 * Use HR-timers to deliver accurate preemption points.
    759 */
    760
    761static void hrtick_clear(struct rq *rq)
    762{
    763	if (hrtimer_active(&rq->hrtick_timer))
    764		hrtimer_cancel(&rq->hrtick_timer);
    765}
    766
    767/*
    768 * High-resolution timer tick.
    769 * Runs from hardirq context with interrupts disabled.
    770 */
    771static enum hrtimer_restart hrtick(struct hrtimer *timer)
    772{
    773	struct rq *rq = container_of(timer, struct rq, hrtick_timer);
    774	struct rq_flags rf;
    775
    776	WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
    777
    778	rq_lock(rq, &rf);
    779	update_rq_clock(rq);
    780	rq->curr->sched_class->task_tick(rq, rq->curr, 1);
    781	rq_unlock(rq, &rf);
    782
    783	return HRTIMER_NORESTART;
    784}
    785
    786#ifdef CONFIG_SMP
    787
    788static void __hrtick_restart(struct rq *rq)
    789{
    790	struct hrtimer *timer = &rq->hrtick_timer;
    791	ktime_t time = rq->hrtick_time;
    792
    793	hrtimer_start(timer, time, HRTIMER_MODE_ABS_PINNED_HARD);
    794}
    795
    796/*
    797 * called from hardirq (IPI) context
    798 */
    799static void __hrtick_start(void *arg)
    800{
    801	struct rq *rq = arg;
    802	struct rq_flags rf;
    803
    804	rq_lock(rq, &rf);
    805	__hrtick_restart(rq);
    806	rq_unlock(rq, &rf);
    807}
    808
    809/*
    810 * Called to set the hrtick timer state.
    811 *
    812 * called with rq->lock held and irqs disabled
    813 */
    814void hrtick_start(struct rq *rq, u64 delay)
    815{
    816	struct hrtimer *timer = &rq->hrtick_timer;
    817	s64 delta;
    818
    819	/*
    820	 * Don't schedule slices shorter than 10000ns, that just
    821	 * doesn't make sense and can cause timer DoS.
    822	 */
    823	delta = max_t(s64, delay, 10000LL);
    824	rq->hrtick_time = ktime_add_ns(timer->base->get_time(), delta);
    825
    826	if (rq == this_rq())
    827		__hrtick_restart(rq);
    828	else
    829		smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
    830}
    831
    832#else
    833/*
    834 * Called to set the hrtick timer state.
    835 *
    836 * called with rq->lock held and irqs disabled
    837 */
    838void hrtick_start(struct rq *rq, u64 delay)
    839{
    840	/*
    841	 * Don't schedule slices shorter than 10000ns, that just
    842	 * doesn't make sense. Rely on vruntime for fairness.
    843	 */
    844	delay = max_t(u64, delay, 10000LL);
    845	hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
    846		      HRTIMER_MODE_REL_PINNED_HARD);
    847}
    848
    849#endif /* CONFIG_SMP */
    850
    851static void hrtick_rq_init(struct rq *rq)
    852{
    853#ifdef CONFIG_SMP
    854	INIT_CSD(&rq->hrtick_csd, __hrtick_start, rq);
    855#endif
    856	hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
    857	rq->hrtick_timer.function = hrtick;
    858}
    859#else	/* CONFIG_SCHED_HRTICK */
    860static inline void hrtick_clear(struct rq *rq)
    861{
    862}
    863
    864static inline void hrtick_rq_init(struct rq *rq)
    865{
    866}
    867#endif	/* CONFIG_SCHED_HRTICK */
    868
    869/*
    870 * cmpxchg based fetch_or, macro so it works for different integer types
    871 */
    872#define fetch_or(ptr, mask)						\
    873	({								\
    874		typeof(ptr) _ptr = (ptr);				\
    875		typeof(mask) _mask = (mask);				\
    876		typeof(*_ptr) _old, _val = *_ptr;			\
    877									\
    878		for (;;) {						\
    879			_old = cmpxchg(_ptr, _val, _val | _mask);	\
    880			if (_old == _val)				\
    881				break;					\
    882			_val = _old;					\
    883		}							\
    884	_old;								\
    885})
    886
    887#if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
    888/*
    889 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
    890 * this avoids any races wrt polling state changes and thereby avoids
    891 * spurious IPIs.
    892 */
    893static bool set_nr_and_not_polling(struct task_struct *p)
    894{
    895	struct thread_info *ti = task_thread_info(p);
    896	return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
    897}
    898
    899/*
    900 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
    901 *
    902 * If this returns true, then the idle task promises to call
    903 * sched_ttwu_pending() and reschedule soon.
    904 */
    905static bool set_nr_if_polling(struct task_struct *p)
    906{
    907	struct thread_info *ti = task_thread_info(p);
    908	typeof(ti->flags) old, val = READ_ONCE(ti->flags);
    909
    910	for (;;) {
    911		if (!(val & _TIF_POLLING_NRFLAG))
    912			return false;
    913		if (val & _TIF_NEED_RESCHED)
    914			return true;
    915		old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
    916		if (old == val)
    917			break;
    918		val = old;
    919	}
    920	return true;
    921}
    922
    923#else
    924static bool set_nr_and_not_polling(struct task_struct *p)
    925{
    926	set_tsk_need_resched(p);
    927	return true;
    928}
    929
    930#ifdef CONFIG_SMP
    931static bool set_nr_if_polling(struct task_struct *p)
    932{
    933	return false;
    934}
    935#endif
    936#endif
    937
    938static bool __wake_q_add(struct wake_q_head *head, struct task_struct *task)
    939{
    940	struct wake_q_node *node = &task->wake_q;
    941
    942	/*
    943	 * Atomically grab the task, if ->wake_q is !nil already it means
    944	 * it's already queued (either by us or someone else) and will get the
    945	 * wakeup due to that.
    946	 *
    947	 * In order to ensure that a pending wakeup will observe our pending
    948	 * state, even in the failed case, an explicit smp_mb() must be used.
    949	 */
    950	smp_mb__before_atomic();
    951	if (unlikely(cmpxchg_relaxed(&node->next, NULL, WAKE_Q_TAIL)))
    952		return false;
    953
    954	/*
    955	 * The head is context local, there can be no concurrency.
    956	 */
    957	*head->lastp = node;
    958	head->lastp = &node->next;
    959	return true;
    960}
    961
    962/**
    963 * wake_q_add() - queue a wakeup for 'later' waking.
    964 * @head: the wake_q_head to add @task to
    965 * @task: the task to queue for 'later' wakeup
    966 *
    967 * Queue a task for later wakeup, most likely by the wake_up_q() call in the
    968 * same context, _HOWEVER_ this is not guaranteed, the wakeup can come
    969 * instantly.
    970 *
    971 * This function must be used as-if it were wake_up_process(); IOW the task
    972 * must be ready to be woken at this location.
    973 */
    974void wake_q_add(struct wake_q_head *head, struct task_struct *task)
    975{
    976	if (__wake_q_add(head, task))
    977		get_task_struct(task);
    978}
    979
    980/**
    981 * wake_q_add_safe() - safely queue a wakeup for 'later' waking.
    982 * @head: the wake_q_head to add @task to
    983 * @task: the task to queue for 'later' wakeup
    984 *
    985 * Queue a task for later wakeup, most likely by the wake_up_q() call in the
    986 * same context, _HOWEVER_ this is not guaranteed, the wakeup can come
    987 * instantly.
    988 *
    989 * This function must be used as-if it were wake_up_process(); IOW the task
    990 * must be ready to be woken at this location.
    991 *
    992 * This function is essentially a task-safe equivalent to wake_q_add(). Callers
    993 * that already hold reference to @task can call the 'safe' version and trust
    994 * wake_q to do the right thing depending whether or not the @task is already
    995 * queued for wakeup.
    996 */
    997void wake_q_add_safe(struct wake_q_head *head, struct task_struct *task)
    998{
    999	if (!__wake_q_add(head, task))
   1000		put_task_struct(task);
   1001}
   1002
   1003void wake_up_q(struct wake_q_head *head)
   1004{
   1005	struct wake_q_node *node = head->first;
   1006
   1007	while (node != WAKE_Q_TAIL) {
   1008		struct task_struct *task;
   1009
   1010		task = container_of(node, struct task_struct, wake_q);
   1011		/* Task can safely be re-inserted now: */
   1012		node = node->next;
   1013		task->wake_q.next = NULL;
   1014
   1015		/*
   1016		 * wake_up_process() executes a full barrier, which pairs with
   1017		 * the queueing in wake_q_add() so as not to miss wakeups.
   1018		 */
   1019		wake_up_process(task);
   1020		put_task_struct(task);
   1021	}
   1022}
   1023
   1024/*
   1025 * resched_curr - mark rq's current task 'to be rescheduled now'.
   1026 *
   1027 * On UP this means the setting of the need_resched flag, on SMP it
   1028 * might also involve a cross-CPU call to trigger the scheduler on
   1029 * the target CPU.
   1030 */
   1031void resched_curr(struct rq *rq)
   1032{
   1033	struct task_struct *curr = rq->curr;
   1034	int cpu;
   1035
   1036	lockdep_assert_rq_held(rq);
   1037
   1038	if (test_tsk_need_resched(curr))
   1039		return;
   1040
   1041	cpu = cpu_of(rq);
   1042
   1043	if (cpu == smp_processor_id()) {
   1044		set_tsk_need_resched(curr);
   1045		set_preempt_need_resched();
   1046		return;
   1047	}
   1048
   1049	if (set_nr_and_not_polling(curr))
   1050		smp_send_reschedule(cpu);
   1051	else
   1052		trace_sched_wake_idle_without_ipi(cpu);
   1053}
   1054
   1055void resched_cpu(int cpu)
   1056{
   1057	struct rq *rq = cpu_rq(cpu);
   1058	unsigned long flags;
   1059
   1060	raw_spin_rq_lock_irqsave(rq, flags);
   1061	if (cpu_online(cpu) || cpu == smp_processor_id())
   1062		resched_curr(rq);
   1063	raw_spin_rq_unlock_irqrestore(rq, flags);
   1064}
   1065
   1066#ifdef CONFIG_SMP
   1067#ifdef CONFIG_NO_HZ_COMMON
   1068/*
   1069 * In the semi idle case, use the nearest busy CPU for migrating timers
   1070 * from an idle CPU.  This is good for power-savings.
   1071 *
   1072 * We don't do similar optimization for completely idle system, as
   1073 * selecting an idle CPU will add more delays to the timers than intended
   1074 * (as that CPU's timer base may not be uptodate wrt jiffies etc).
   1075 */
   1076int get_nohz_timer_target(void)
   1077{
   1078	int i, cpu = smp_processor_id(), default_cpu = -1;
   1079	struct sched_domain *sd;
   1080	const struct cpumask *hk_mask;
   1081
   1082	if (housekeeping_cpu(cpu, HK_TYPE_TIMER)) {
   1083		if (!idle_cpu(cpu))
   1084			return cpu;
   1085		default_cpu = cpu;
   1086	}
   1087
   1088	hk_mask = housekeeping_cpumask(HK_TYPE_TIMER);
   1089
   1090	rcu_read_lock();
   1091	for_each_domain(cpu, sd) {
   1092		for_each_cpu_and(i, sched_domain_span(sd), hk_mask) {
   1093			if (cpu == i)
   1094				continue;
   1095
   1096			if (!idle_cpu(i)) {
   1097				cpu = i;
   1098				goto unlock;
   1099			}
   1100		}
   1101	}
   1102
   1103	if (default_cpu == -1)
   1104		default_cpu = housekeeping_any_cpu(HK_TYPE_TIMER);
   1105	cpu = default_cpu;
   1106unlock:
   1107	rcu_read_unlock();
   1108	return cpu;
   1109}
   1110
   1111/*
   1112 * When add_timer_on() enqueues a timer into the timer wheel of an
   1113 * idle CPU then this timer might expire before the next timer event
   1114 * which is scheduled to wake up that CPU. In case of a completely
   1115 * idle system the next event might even be infinite time into the
   1116 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
   1117 * leaves the inner idle loop so the newly added timer is taken into
   1118 * account when the CPU goes back to idle and evaluates the timer
   1119 * wheel for the next timer event.
   1120 */
   1121static void wake_up_idle_cpu(int cpu)
   1122{
   1123	struct rq *rq = cpu_rq(cpu);
   1124
   1125	if (cpu == smp_processor_id())
   1126		return;
   1127
   1128	if (set_nr_and_not_polling(rq->idle))
   1129		smp_send_reschedule(cpu);
   1130	else
   1131		trace_sched_wake_idle_without_ipi(cpu);
   1132}
   1133
   1134static bool wake_up_full_nohz_cpu(int cpu)
   1135{
   1136	/*
   1137	 * We just need the target to call irq_exit() and re-evaluate
   1138	 * the next tick. The nohz full kick at least implies that.
   1139	 * If needed we can still optimize that later with an
   1140	 * empty IRQ.
   1141	 */
   1142	if (cpu_is_offline(cpu))
   1143		return true;  /* Don't try to wake offline CPUs. */
   1144	if (tick_nohz_full_cpu(cpu)) {
   1145		if (cpu != smp_processor_id() ||
   1146		    tick_nohz_tick_stopped())
   1147			tick_nohz_full_kick_cpu(cpu);
   1148		return true;
   1149	}
   1150
   1151	return false;
   1152}
   1153
   1154/*
   1155 * Wake up the specified CPU.  If the CPU is going offline, it is the
   1156 * caller's responsibility to deal with the lost wakeup, for example,
   1157 * by hooking into the CPU_DEAD notifier like timers and hrtimers do.
   1158 */
   1159void wake_up_nohz_cpu(int cpu)
   1160{
   1161	if (!wake_up_full_nohz_cpu(cpu))
   1162		wake_up_idle_cpu(cpu);
   1163}
   1164
   1165static void nohz_csd_func(void *info)
   1166{
   1167	struct rq *rq = info;
   1168	int cpu = cpu_of(rq);
   1169	unsigned int flags;
   1170
   1171	/*
   1172	 * Release the rq::nohz_csd.
   1173	 */
   1174	flags = atomic_fetch_andnot(NOHZ_KICK_MASK | NOHZ_NEWILB_KICK, nohz_flags(cpu));
   1175	WARN_ON(!(flags & NOHZ_KICK_MASK));
   1176
   1177	rq->idle_balance = idle_cpu(cpu);
   1178	if (rq->idle_balance && !need_resched()) {
   1179		rq->nohz_idle_balance = flags;
   1180		raise_softirq_irqoff(SCHED_SOFTIRQ);
   1181	}
   1182}
   1183
   1184#endif /* CONFIG_NO_HZ_COMMON */
   1185
   1186#ifdef CONFIG_NO_HZ_FULL
   1187bool sched_can_stop_tick(struct rq *rq)
   1188{
   1189	int fifo_nr_running;
   1190
   1191	/* Deadline tasks, even if single, need the tick */
   1192	if (rq->dl.dl_nr_running)
   1193		return false;
   1194
   1195	/*
   1196	 * If there are more than one RR tasks, we need the tick to affect the
   1197	 * actual RR behaviour.
   1198	 */
   1199	if (rq->rt.rr_nr_running) {
   1200		if (rq->rt.rr_nr_running == 1)
   1201			return true;
   1202		else
   1203			return false;
   1204	}
   1205
   1206	/*
   1207	 * If there's no RR tasks, but FIFO tasks, we can skip the tick, no
   1208	 * forced preemption between FIFO tasks.
   1209	 */
   1210	fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
   1211	if (fifo_nr_running)
   1212		return true;
   1213
   1214	/*
   1215	 * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left;
   1216	 * if there's more than one we need the tick for involuntary
   1217	 * preemption.
   1218	 */
   1219	if (rq->nr_running > 1)
   1220		return false;
   1221
   1222	return true;
   1223}
   1224#endif /* CONFIG_NO_HZ_FULL */
   1225#endif /* CONFIG_SMP */
   1226
   1227#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
   1228			(defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
   1229/*
   1230 * Iterate task_group tree rooted at *from, calling @down when first entering a
   1231 * node and @up when leaving it for the final time.
   1232 *
   1233 * Caller must hold rcu_lock or sufficient equivalent.
   1234 */
   1235int walk_tg_tree_from(struct task_group *from,
   1236			     tg_visitor down, tg_visitor up, void *data)
   1237{
   1238	struct task_group *parent, *child;
   1239	int ret;
   1240
   1241	parent = from;
   1242
   1243down:
   1244	ret = (*down)(parent, data);
   1245	if (ret)
   1246		goto out;
   1247	list_for_each_entry_rcu(child, &parent->children, siblings) {
   1248		parent = child;
   1249		goto down;
   1250
   1251up:
   1252		continue;
   1253	}
   1254	ret = (*up)(parent, data);
   1255	if (ret || parent == from)
   1256		goto out;
   1257
   1258	child = parent;
   1259	parent = parent->parent;
   1260	if (parent)
   1261		goto up;
   1262out:
   1263	return ret;
   1264}
   1265
   1266int tg_nop(struct task_group *tg, void *data)
   1267{
   1268	return 0;
   1269}
   1270#endif
   1271
   1272static void set_load_weight(struct task_struct *p, bool update_load)
   1273{
   1274	int prio = p->static_prio - MAX_RT_PRIO;
   1275	struct load_weight *load = &p->se.load;
   1276
   1277	/*
   1278	 * SCHED_IDLE tasks get minimal weight:
   1279	 */
   1280	if (task_has_idle_policy(p)) {
   1281		load->weight = scale_load(WEIGHT_IDLEPRIO);
   1282		load->inv_weight = WMULT_IDLEPRIO;
   1283		return;
   1284	}
   1285
   1286	/*
   1287	 * SCHED_OTHER tasks have to update their load when changing their
   1288	 * weight
   1289	 */
   1290	if (update_load && p->sched_class == &fair_sched_class) {
   1291		reweight_task(p, prio);
   1292	} else {
   1293		load->weight = scale_load(sched_prio_to_weight[prio]);
   1294		load->inv_weight = sched_prio_to_wmult[prio];
   1295	}
   1296}
   1297
   1298#ifdef CONFIG_UCLAMP_TASK
   1299/*
   1300 * Serializes updates of utilization clamp values
   1301 *
   1302 * The (slow-path) user-space triggers utilization clamp value updates which
   1303 * can require updates on (fast-path) scheduler's data structures used to
   1304 * support enqueue/dequeue operations.
   1305 * While the per-CPU rq lock protects fast-path update operations, user-space
   1306 * requests are serialized using a mutex to reduce the risk of conflicting
   1307 * updates or API abuses.
   1308 */
   1309static DEFINE_MUTEX(uclamp_mutex);
   1310
   1311/* Max allowed minimum utilization */
   1312static unsigned int __maybe_unused sysctl_sched_uclamp_util_min = SCHED_CAPACITY_SCALE;
   1313
   1314/* Max allowed maximum utilization */
   1315static unsigned int __maybe_unused sysctl_sched_uclamp_util_max = SCHED_CAPACITY_SCALE;
   1316
   1317/*
   1318 * By default RT tasks run at the maximum performance point/capacity of the
   1319 * system. Uclamp enforces this by always setting UCLAMP_MIN of RT tasks to
   1320 * SCHED_CAPACITY_SCALE.
   1321 *
   1322 * This knob allows admins to change the default behavior when uclamp is being
   1323 * used. In battery powered devices, particularly, running at the maximum
   1324 * capacity and frequency will increase energy consumption and shorten the
   1325 * battery life.
   1326 *
   1327 * This knob only affects RT tasks that their uclamp_se->user_defined == false.
   1328 *
   1329 * This knob will not override the system default sched_util_clamp_min defined
   1330 * above.
   1331 */
   1332static unsigned int sysctl_sched_uclamp_util_min_rt_default = SCHED_CAPACITY_SCALE;
   1333
   1334/* All clamps are required to be less or equal than these values */
   1335static struct uclamp_se uclamp_default[UCLAMP_CNT];
   1336
   1337/*
   1338 * This static key is used to reduce the uclamp overhead in the fast path. It
   1339 * primarily disables the call to uclamp_rq_{inc, dec}() in
   1340 * enqueue/dequeue_task().
   1341 *
   1342 * This allows users to continue to enable uclamp in their kernel config with
   1343 * minimum uclamp overhead in the fast path.
   1344 *
   1345 * As soon as userspace modifies any of the uclamp knobs, the static key is
   1346 * enabled, since we have an actual users that make use of uclamp
   1347 * functionality.
   1348 *
   1349 * The knobs that would enable this static key are:
   1350 *
   1351 *   * A task modifying its uclamp value with sched_setattr().
   1352 *   * An admin modifying the sysctl_sched_uclamp_{min, max} via procfs.
   1353 *   * An admin modifying the cgroup cpu.uclamp.{min, max}
   1354 */
   1355DEFINE_STATIC_KEY_FALSE(sched_uclamp_used);
   1356
   1357/* Integer rounded range for each bucket */
   1358#define UCLAMP_BUCKET_DELTA DIV_ROUND_CLOSEST(SCHED_CAPACITY_SCALE, UCLAMP_BUCKETS)
   1359
   1360#define for_each_clamp_id(clamp_id) \
   1361	for ((clamp_id) = 0; (clamp_id) < UCLAMP_CNT; (clamp_id)++)
   1362
   1363static inline unsigned int uclamp_bucket_id(unsigned int clamp_value)
   1364{
   1365	return min_t(unsigned int, clamp_value / UCLAMP_BUCKET_DELTA, UCLAMP_BUCKETS - 1);
   1366}
   1367
   1368static inline unsigned int uclamp_none(enum uclamp_id clamp_id)
   1369{
   1370	if (clamp_id == UCLAMP_MIN)
   1371		return 0;
   1372	return SCHED_CAPACITY_SCALE;
   1373}
   1374
   1375static inline void uclamp_se_set(struct uclamp_se *uc_se,
   1376				 unsigned int value, bool user_defined)
   1377{
   1378	uc_se->value = value;
   1379	uc_se->bucket_id = uclamp_bucket_id(value);
   1380	uc_se->user_defined = user_defined;
   1381}
   1382
   1383static inline unsigned int
   1384uclamp_idle_value(struct rq *rq, enum uclamp_id clamp_id,
   1385		  unsigned int clamp_value)
   1386{
   1387	/*
   1388	 * Avoid blocked utilization pushing up the frequency when we go
   1389	 * idle (which drops the max-clamp) by retaining the last known
   1390	 * max-clamp.
   1391	 */
   1392	if (clamp_id == UCLAMP_MAX) {
   1393		rq->uclamp_flags |= UCLAMP_FLAG_IDLE;
   1394		return clamp_value;
   1395	}
   1396
   1397	return uclamp_none(UCLAMP_MIN);
   1398}
   1399
   1400static inline void uclamp_idle_reset(struct rq *rq, enum uclamp_id clamp_id,
   1401				     unsigned int clamp_value)
   1402{
   1403	/* Reset max-clamp retention only on idle exit */
   1404	if (!(rq->uclamp_flags & UCLAMP_FLAG_IDLE))
   1405		return;
   1406
   1407	WRITE_ONCE(rq->uclamp[clamp_id].value, clamp_value);
   1408}
   1409
   1410static inline
   1411unsigned int uclamp_rq_max_value(struct rq *rq, enum uclamp_id clamp_id,
   1412				   unsigned int clamp_value)
   1413{
   1414	struct uclamp_bucket *bucket = rq->uclamp[clamp_id].bucket;
   1415	int bucket_id = UCLAMP_BUCKETS - 1;
   1416
   1417	/*
   1418	 * Since both min and max clamps are max aggregated, find the
   1419	 * top most bucket with tasks in.
   1420	 */
   1421	for ( ; bucket_id >= 0; bucket_id--) {
   1422		if (!bucket[bucket_id].tasks)
   1423			continue;
   1424		return bucket[bucket_id].value;
   1425	}
   1426
   1427	/* No tasks -- default clamp values */
   1428	return uclamp_idle_value(rq, clamp_id, clamp_value);
   1429}
   1430
   1431static void __uclamp_update_util_min_rt_default(struct task_struct *p)
   1432{
   1433	unsigned int default_util_min;
   1434	struct uclamp_se *uc_se;
   1435
   1436	lockdep_assert_held(&p->pi_lock);
   1437
   1438	uc_se = &p->uclamp_req[UCLAMP_MIN];
   1439
   1440	/* Only sync if user didn't override the default */
   1441	if (uc_se->user_defined)
   1442		return;
   1443
   1444	default_util_min = sysctl_sched_uclamp_util_min_rt_default;
   1445	uclamp_se_set(uc_se, default_util_min, false);
   1446}
   1447
   1448static void uclamp_update_util_min_rt_default(struct task_struct *p)
   1449{
   1450	struct rq_flags rf;
   1451	struct rq *rq;
   1452
   1453	if (!rt_task(p))
   1454		return;
   1455
   1456	/* Protect updates to p->uclamp_* */
   1457	rq = task_rq_lock(p, &rf);
   1458	__uclamp_update_util_min_rt_default(p);
   1459	task_rq_unlock(rq, p, &rf);
   1460}
   1461
   1462static inline struct uclamp_se
   1463uclamp_tg_restrict(struct task_struct *p, enum uclamp_id clamp_id)
   1464{
   1465	/* Copy by value as we could modify it */
   1466	struct uclamp_se uc_req = p->uclamp_req[clamp_id];
   1467#ifdef CONFIG_UCLAMP_TASK_GROUP
   1468	unsigned int tg_min, tg_max, value;
   1469
   1470	/*
   1471	 * Tasks in autogroups or root task group will be
   1472	 * restricted by system defaults.
   1473	 */
   1474	if (task_group_is_autogroup(task_group(p)))
   1475		return uc_req;
   1476	if (task_group(p) == &root_task_group)
   1477		return uc_req;
   1478
   1479	tg_min = task_group(p)->uclamp[UCLAMP_MIN].value;
   1480	tg_max = task_group(p)->uclamp[UCLAMP_MAX].value;
   1481	value = uc_req.value;
   1482	value = clamp(value, tg_min, tg_max);
   1483	uclamp_se_set(&uc_req, value, false);
   1484#endif
   1485
   1486	return uc_req;
   1487}
   1488
   1489/*
   1490 * The effective clamp bucket index of a task depends on, by increasing
   1491 * priority:
   1492 * - the task specific clamp value, when explicitly requested from userspace
   1493 * - the task group effective clamp value, for tasks not either in the root
   1494 *   group or in an autogroup
   1495 * - the system default clamp value, defined by the sysadmin
   1496 */
   1497static inline struct uclamp_se
   1498uclamp_eff_get(struct task_struct *p, enum uclamp_id clamp_id)
   1499{
   1500	struct uclamp_se uc_req = uclamp_tg_restrict(p, clamp_id);
   1501	struct uclamp_se uc_max = uclamp_default[clamp_id];
   1502
   1503	/* System default restrictions always apply */
   1504	if (unlikely(uc_req.value > uc_max.value))
   1505		return uc_max;
   1506
   1507	return uc_req;
   1508}
   1509
   1510unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id)
   1511{
   1512	struct uclamp_se uc_eff;
   1513
   1514	/* Task currently refcounted: use back-annotated (effective) value */
   1515	if (p->uclamp[clamp_id].active)
   1516		return (unsigned long)p->uclamp[clamp_id].value;
   1517
   1518	uc_eff = uclamp_eff_get(p, clamp_id);
   1519
   1520	return (unsigned long)uc_eff.value;
   1521}
   1522
   1523/*
   1524 * When a task is enqueued on a rq, the clamp bucket currently defined by the
   1525 * task's uclamp::bucket_id is refcounted on that rq. This also immediately
   1526 * updates the rq's clamp value if required.
   1527 *
   1528 * Tasks can have a task-specific value requested from user-space, track
   1529 * within each bucket the maximum value for tasks refcounted in it.
   1530 * This "local max aggregation" allows to track the exact "requested" value
   1531 * for each bucket when all its RUNNABLE tasks require the same clamp.
   1532 */
   1533static inline void uclamp_rq_inc_id(struct rq *rq, struct task_struct *p,
   1534				    enum uclamp_id clamp_id)
   1535{
   1536	struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id];
   1537	struct uclamp_se *uc_se = &p->uclamp[clamp_id];
   1538	struct uclamp_bucket *bucket;
   1539
   1540	lockdep_assert_rq_held(rq);
   1541
   1542	/* Update task effective clamp */
   1543	p->uclamp[clamp_id] = uclamp_eff_get(p, clamp_id);
   1544
   1545	bucket = &uc_rq->bucket[uc_se->bucket_id];
   1546	bucket->tasks++;
   1547	uc_se->active = true;
   1548
   1549	uclamp_idle_reset(rq, clamp_id, uc_se->value);
   1550
   1551	/*
   1552	 * Local max aggregation: rq buckets always track the max
   1553	 * "requested" clamp value of its RUNNABLE tasks.
   1554	 */
   1555	if (bucket->tasks == 1 || uc_se->value > bucket->value)
   1556		bucket->value = uc_se->value;
   1557
   1558	if (uc_se->value > READ_ONCE(uc_rq->value))
   1559		WRITE_ONCE(uc_rq->value, uc_se->value);
   1560}
   1561
   1562/*
   1563 * When a task is dequeued from a rq, the clamp bucket refcounted by the task
   1564 * is released. If this is the last task reference counting the rq's max
   1565 * active clamp value, then the rq's clamp value is updated.
   1566 *
   1567 * Both refcounted tasks and rq's cached clamp values are expected to be
   1568 * always valid. If it's detected they are not, as defensive programming,
   1569 * enforce the expected state and warn.
   1570 */
   1571static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p,
   1572				    enum uclamp_id clamp_id)
   1573{
   1574	struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id];
   1575	struct uclamp_se *uc_se = &p->uclamp[clamp_id];
   1576	struct uclamp_bucket *bucket;
   1577	unsigned int bkt_clamp;
   1578	unsigned int rq_clamp;
   1579
   1580	lockdep_assert_rq_held(rq);
   1581
   1582	/*
   1583	 * If sched_uclamp_used was enabled after task @p was enqueued,
   1584	 * we could end up with unbalanced call to uclamp_rq_dec_id().
   1585	 *
   1586	 * In this case the uc_se->active flag should be false since no uclamp
   1587	 * accounting was performed at enqueue time and we can just return
   1588	 * here.
   1589	 *
   1590	 * Need to be careful of the following enqueue/dequeue ordering
   1591	 * problem too
   1592	 *
   1593	 *	enqueue(taskA)
   1594	 *	// sched_uclamp_used gets enabled
   1595	 *	enqueue(taskB)
   1596	 *	dequeue(taskA)
   1597	 *	// Must not decrement bucket->tasks here
   1598	 *	dequeue(taskB)
   1599	 *
   1600	 * where we could end up with stale data in uc_se and
   1601	 * bucket[uc_se->bucket_id].
   1602	 *
   1603	 * The following check here eliminates the possibility of such race.
   1604	 */
   1605	if (unlikely(!uc_se->active))
   1606		return;
   1607
   1608	bucket = &uc_rq->bucket[uc_se->bucket_id];
   1609
   1610	SCHED_WARN_ON(!bucket->tasks);
   1611	if (likely(bucket->tasks))
   1612		bucket->tasks--;
   1613
   1614	uc_se->active = false;
   1615
   1616	/*
   1617	 * Keep "local max aggregation" simple and accept to (possibly)
   1618	 * overboost some RUNNABLE tasks in the same bucket.
   1619	 * The rq clamp bucket value is reset to its base value whenever
   1620	 * there are no more RUNNABLE tasks refcounting it.
   1621	 */
   1622	if (likely(bucket->tasks))
   1623		return;
   1624
   1625	rq_clamp = READ_ONCE(uc_rq->value);
   1626	/*
   1627	 * Defensive programming: this should never happen. If it happens,
   1628	 * e.g. due to future modification, warn and fixup the expected value.
   1629	 */
   1630	SCHED_WARN_ON(bucket->value > rq_clamp);
   1631	if (bucket->value >= rq_clamp) {
   1632		bkt_clamp = uclamp_rq_max_value(rq, clamp_id, uc_se->value);
   1633		WRITE_ONCE(uc_rq->value, bkt_clamp);
   1634	}
   1635}
   1636
   1637static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p)
   1638{
   1639	enum uclamp_id clamp_id;
   1640
   1641	/*
   1642	 * Avoid any overhead until uclamp is actually used by the userspace.
   1643	 *
   1644	 * The condition is constructed such that a NOP is generated when
   1645	 * sched_uclamp_used is disabled.
   1646	 */
   1647	if (!static_branch_unlikely(&sched_uclamp_used))
   1648		return;
   1649
   1650	if (unlikely(!p->sched_class->uclamp_enabled))
   1651		return;
   1652
   1653	for_each_clamp_id(clamp_id)
   1654		uclamp_rq_inc_id(rq, p, clamp_id);
   1655
   1656	/* Reset clamp idle holding when there is one RUNNABLE task */
   1657	if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
   1658		rq->uclamp_flags &= ~UCLAMP_FLAG_IDLE;
   1659}
   1660
   1661static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p)
   1662{
   1663	enum uclamp_id clamp_id;
   1664
   1665	/*
   1666	 * Avoid any overhead until uclamp is actually used by the userspace.
   1667	 *
   1668	 * The condition is constructed such that a NOP is generated when
   1669	 * sched_uclamp_used is disabled.
   1670	 */
   1671	if (!static_branch_unlikely(&sched_uclamp_used))
   1672		return;
   1673
   1674	if (unlikely(!p->sched_class->uclamp_enabled))
   1675		return;
   1676
   1677	for_each_clamp_id(clamp_id)
   1678		uclamp_rq_dec_id(rq, p, clamp_id);
   1679}
   1680
   1681static inline void uclamp_rq_reinc_id(struct rq *rq, struct task_struct *p,
   1682				      enum uclamp_id clamp_id)
   1683{
   1684	if (!p->uclamp[clamp_id].active)
   1685		return;
   1686
   1687	uclamp_rq_dec_id(rq, p, clamp_id);
   1688	uclamp_rq_inc_id(rq, p, clamp_id);
   1689
   1690	/*
   1691	 * Make sure to clear the idle flag if we've transiently reached 0
   1692	 * active tasks on rq.
   1693	 */
   1694	if (clamp_id == UCLAMP_MAX && (rq->uclamp_flags & UCLAMP_FLAG_IDLE))
   1695		rq->uclamp_flags &= ~UCLAMP_FLAG_IDLE;
   1696}
   1697
   1698static inline void
   1699uclamp_update_active(struct task_struct *p)
   1700{
   1701	enum uclamp_id clamp_id;
   1702	struct rq_flags rf;
   1703	struct rq *rq;
   1704
   1705	/*
   1706	 * Lock the task and the rq where the task is (or was) queued.
   1707	 *
   1708	 * We might lock the (previous) rq of a !RUNNABLE task, but that's the
   1709	 * price to pay to safely serialize util_{min,max} updates with
   1710	 * enqueues, dequeues and migration operations.
   1711	 * This is the same locking schema used by __set_cpus_allowed_ptr().
   1712	 */
   1713	rq = task_rq_lock(p, &rf);
   1714
   1715	/*
   1716	 * Setting the clamp bucket is serialized by task_rq_lock().
   1717	 * If the task is not yet RUNNABLE and its task_struct is not
   1718	 * affecting a valid clamp bucket, the next time it's enqueued,
   1719	 * it will already see the updated clamp bucket value.
   1720	 */
   1721	for_each_clamp_id(clamp_id)
   1722		uclamp_rq_reinc_id(rq, p, clamp_id);
   1723
   1724	task_rq_unlock(rq, p, &rf);
   1725}
   1726
   1727#ifdef CONFIG_UCLAMP_TASK_GROUP
   1728static inline void
   1729uclamp_update_active_tasks(struct cgroup_subsys_state *css)
   1730{
   1731	struct css_task_iter it;
   1732	struct task_struct *p;
   1733
   1734	css_task_iter_start(css, 0, &it);
   1735	while ((p = css_task_iter_next(&it)))
   1736		uclamp_update_active(p);
   1737	css_task_iter_end(&it);
   1738}
   1739
   1740static void cpu_util_update_eff(struct cgroup_subsys_state *css);
   1741#endif
   1742
   1743#ifdef CONFIG_SYSCTL
   1744#ifdef CONFIG_UCLAMP_TASK
   1745#ifdef CONFIG_UCLAMP_TASK_GROUP
   1746static void uclamp_update_root_tg(void)
   1747{
   1748	struct task_group *tg = &root_task_group;
   1749
   1750	uclamp_se_set(&tg->uclamp_req[UCLAMP_MIN],
   1751		      sysctl_sched_uclamp_util_min, false);
   1752	uclamp_se_set(&tg->uclamp_req[UCLAMP_MAX],
   1753		      sysctl_sched_uclamp_util_max, false);
   1754
   1755	rcu_read_lock();
   1756	cpu_util_update_eff(&root_task_group.css);
   1757	rcu_read_unlock();
   1758}
   1759#else
   1760static void uclamp_update_root_tg(void) { }
   1761#endif
   1762
   1763static void uclamp_sync_util_min_rt_default(void)
   1764{
   1765	struct task_struct *g, *p;
   1766
   1767	/*
   1768	 * copy_process()			sysctl_uclamp
   1769	 *					  uclamp_min_rt = X;
   1770	 *   write_lock(&tasklist_lock)		  read_lock(&tasklist_lock)
   1771	 *   // link thread			  smp_mb__after_spinlock()
   1772	 *   write_unlock(&tasklist_lock)	  read_unlock(&tasklist_lock);
   1773	 *   sched_post_fork()			  for_each_process_thread()
   1774	 *     __uclamp_sync_rt()		    __uclamp_sync_rt()
   1775	 *
   1776	 * Ensures that either sched_post_fork() will observe the new
   1777	 * uclamp_min_rt or for_each_process_thread() will observe the new
   1778	 * task.
   1779	 */
   1780	read_lock(&tasklist_lock);
   1781	smp_mb__after_spinlock();
   1782	read_unlock(&tasklist_lock);
   1783
   1784	rcu_read_lock();
   1785	for_each_process_thread(g, p)
   1786		uclamp_update_util_min_rt_default(p);
   1787	rcu_read_unlock();
   1788}
   1789
   1790static int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
   1791				void *buffer, size_t *lenp, loff_t *ppos)
   1792{
   1793	bool update_root_tg = false;
   1794	int old_min, old_max, old_min_rt;
   1795	int result;
   1796
   1797	mutex_lock(&uclamp_mutex);
   1798	old_min = sysctl_sched_uclamp_util_min;
   1799	old_max = sysctl_sched_uclamp_util_max;
   1800	old_min_rt = sysctl_sched_uclamp_util_min_rt_default;
   1801
   1802	result = proc_dointvec(table, write, buffer, lenp, ppos);
   1803	if (result)
   1804		goto undo;
   1805	if (!write)
   1806		goto done;
   1807
   1808	if (sysctl_sched_uclamp_util_min > sysctl_sched_uclamp_util_max ||
   1809	    sysctl_sched_uclamp_util_max > SCHED_CAPACITY_SCALE	||
   1810	    sysctl_sched_uclamp_util_min_rt_default > SCHED_CAPACITY_SCALE) {
   1811
   1812		result = -EINVAL;
   1813		goto undo;
   1814	}
   1815
   1816	if (old_min != sysctl_sched_uclamp_util_min) {
   1817		uclamp_se_set(&uclamp_default[UCLAMP_MIN],
   1818			      sysctl_sched_uclamp_util_min, false);
   1819		update_root_tg = true;
   1820	}
   1821	if (old_max != sysctl_sched_uclamp_util_max) {
   1822		uclamp_se_set(&uclamp_default[UCLAMP_MAX],
   1823			      sysctl_sched_uclamp_util_max, false);
   1824		update_root_tg = true;
   1825	}
   1826
   1827	if (update_root_tg) {
   1828		static_branch_enable(&sched_uclamp_used);
   1829		uclamp_update_root_tg();
   1830	}
   1831
   1832	if (old_min_rt != sysctl_sched_uclamp_util_min_rt_default) {
   1833		static_branch_enable(&sched_uclamp_used);
   1834		uclamp_sync_util_min_rt_default();
   1835	}
   1836
   1837	/*
   1838	 * We update all RUNNABLE tasks only when task groups are in use.
   1839	 * Otherwise, keep it simple and do just a lazy update at each next
   1840	 * task enqueue time.
   1841	 */
   1842
   1843	goto done;
   1844
   1845undo:
   1846	sysctl_sched_uclamp_util_min = old_min;
   1847	sysctl_sched_uclamp_util_max = old_max;
   1848	sysctl_sched_uclamp_util_min_rt_default = old_min_rt;
   1849done:
   1850	mutex_unlock(&uclamp_mutex);
   1851
   1852	return result;
   1853}
   1854#endif
   1855#endif
   1856
   1857static int uclamp_validate(struct task_struct *p,
   1858			   const struct sched_attr *attr)
   1859{
   1860	int util_min = p->uclamp_req[UCLAMP_MIN].value;
   1861	int util_max = p->uclamp_req[UCLAMP_MAX].value;
   1862
   1863	if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) {
   1864		util_min = attr->sched_util_min;
   1865
   1866		if (util_min + 1 > SCHED_CAPACITY_SCALE + 1)
   1867			return -EINVAL;
   1868	}
   1869
   1870	if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) {
   1871		util_max = attr->sched_util_max;
   1872
   1873		if (util_max + 1 > SCHED_CAPACITY_SCALE + 1)
   1874			return -EINVAL;
   1875	}
   1876
   1877	if (util_min != -1 && util_max != -1 && util_min > util_max)
   1878		return -EINVAL;
   1879
   1880	/*
   1881	 * We have valid uclamp attributes; make sure uclamp is enabled.
   1882	 *
   1883	 * We need to do that here, because enabling static branches is a
   1884	 * blocking operation which obviously cannot be done while holding
   1885	 * scheduler locks.
   1886	 */
   1887	static_branch_enable(&sched_uclamp_used);
   1888
   1889	return 0;
   1890}
   1891
   1892static bool uclamp_reset(const struct sched_attr *attr,
   1893			 enum uclamp_id clamp_id,
   1894			 struct uclamp_se *uc_se)
   1895{
   1896	/* Reset on sched class change for a non user-defined clamp value. */
   1897	if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)) &&
   1898	    !uc_se->user_defined)
   1899		return true;
   1900
   1901	/* Reset on sched_util_{min,max} == -1. */
   1902	if (clamp_id == UCLAMP_MIN &&
   1903	    attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN &&
   1904	    attr->sched_util_min == -1) {
   1905		return true;
   1906	}
   1907
   1908	if (clamp_id == UCLAMP_MAX &&
   1909	    attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX &&
   1910	    attr->sched_util_max == -1) {
   1911		return true;
   1912	}
   1913
   1914	return false;
   1915}
   1916
   1917static void __setscheduler_uclamp(struct task_struct *p,
   1918				  const struct sched_attr *attr)
   1919{
   1920	enum uclamp_id clamp_id;
   1921
   1922	for_each_clamp_id(clamp_id) {
   1923		struct uclamp_se *uc_se = &p->uclamp_req[clamp_id];
   1924		unsigned int value;
   1925
   1926		if (!uclamp_reset(attr, clamp_id, uc_se))
   1927			continue;
   1928
   1929		/*
   1930		 * RT by default have a 100% boost value that could be modified
   1931		 * at runtime.
   1932		 */
   1933		if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN))
   1934			value = sysctl_sched_uclamp_util_min_rt_default;
   1935		else
   1936			value = uclamp_none(clamp_id);
   1937
   1938		uclamp_se_set(uc_se, value, false);
   1939
   1940	}
   1941
   1942	if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)))
   1943		return;
   1944
   1945	if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN &&
   1946	    attr->sched_util_min != -1) {
   1947		uclamp_se_set(&p->uclamp_req[UCLAMP_MIN],
   1948			      attr->sched_util_min, true);
   1949	}
   1950
   1951	if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX &&
   1952	    attr->sched_util_max != -1) {
   1953		uclamp_se_set(&p->uclamp_req[UCLAMP_MAX],
   1954			      attr->sched_util_max, true);
   1955	}
   1956}
   1957
   1958static void uclamp_fork(struct task_struct *p)
   1959{
   1960	enum uclamp_id clamp_id;
   1961
   1962	/*
   1963	 * We don't need to hold task_rq_lock() when updating p->uclamp_* here
   1964	 * as the task is still at its early fork stages.
   1965	 */
   1966	for_each_clamp_id(clamp_id)
   1967		p->uclamp[clamp_id].active = false;
   1968
   1969	if (likely(!p->sched_reset_on_fork))
   1970		return;
   1971
   1972	for_each_clamp_id(clamp_id) {
   1973		uclamp_se_set(&p->uclamp_req[clamp_id],
   1974			      uclamp_none(clamp_id), false);
   1975	}
   1976}
   1977
   1978static void uclamp_post_fork(struct task_struct *p)
   1979{
   1980	uclamp_update_util_min_rt_default(p);
   1981}
   1982
   1983static void __init init_uclamp_rq(struct rq *rq)
   1984{
   1985	enum uclamp_id clamp_id;
   1986	struct uclamp_rq *uc_rq = rq->uclamp;
   1987
   1988	for_each_clamp_id(clamp_id) {
   1989		uc_rq[clamp_id] = (struct uclamp_rq) {
   1990			.value = uclamp_none(clamp_id)
   1991		};
   1992	}
   1993
   1994	rq->uclamp_flags = UCLAMP_FLAG_IDLE;
   1995}
   1996
   1997static void __init init_uclamp(void)
   1998{
   1999	struct uclamp_se uc_max = {};
   2000	enum uclamp_id clamp_id;
   2001	int cpu;
   2002
   2003	for_each_possible_cpu(cpu)
   2004		init_uclamp_rq(cpu_rq(cpu));
   2005
   2006	for_each_clamp_id(clamp_id) {
   2007		uclamp_se_set(&init_task.uclamp_req[clamp_id],
   2008			      uclamp_none(clamp_id), false);
   2009	}
   2010
   2011	/* System defaults allow max clamp values for both indexes */
   2012	uclamp_se_set(&uc_max, uclamp_none(UCLAMP_MAX), false);
   2013	for_each_clamp_id(clamp_id) {
   2014		uclamp_default[clamp_id] = uc_max;
   2015#ifdef CONFIG_UCLAMP_TASK_GROUP
   2016		root_task_group.uclamp_req[clamp_id] = uc_max;
   2017		root_task_group.uclamp[clamp_id] = uc_max;
   2018#endif
   2019	}
   2020}
   2021
   2022#else /* CONFIG_UCLAMP_TASK */
   2023static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p) { }
   2024static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p) { }
   2025static inline int uclamp_validate(struct task_struct *p,
   2026				  const struct sched_attr *attr)
   2027{
   2028	return -EOPNOTSUPP;
   2029}
   2030static void __setscheduler_uclamp(struct task_struct *p,
   2031				  const struct sched_attr *attr) { }
   2032static inline void uclamp_fork(struct task_struct *p) { }
   2033static inline void uclamp_post_fork(struct task_struct *p) { }
   2034static inline void init_uclamp(void) { }
   2035#endif /* CONFIG_UCLAMP_TASK */
   2036
   2037bool sched_task_on_rq(struct task_struct *p)
   2038{
   2039	return task_on_rq_queued(p);
   2040}
   2041
   2042unsigned long get_wchan(struct task_struct *p)
   2043{
   2044	unsigned long ip = 0;
   2045	unsigned int state;
   2046
   2047	if (!p || p == current)
   2048		return 0;
   2049
   2050	/* Only get wchan if task is blocked and we can keep it that way. */
   2051	raw_spin_lock_irq(&p->pi_lock);
   2052	state = READ_ONCE(p->__state);
   2053	smp_rmb(); /* see try_to_wake_up() */
   2054	if (state != TASK_RUNNING && state != TASK_WAKING && !p->on_rq)
   2055		ip = __get_wchan(p);
   2056	raw_spin_unlock_irq(&p->pi_lock);
   2057
   2058	return ip;
   2059}
   2060
   2061static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
   2062{
   2063	if (!(flags & ENQUEUE_NOCLOCK))
   2064		update_rq_clock(rq);
   2065
   2066	if (!(flags & ENQUEUE_RESTORE)) {
   2067		sched_info_enqueue(rq, p);
   2068		psi_enqueue(p, flags & ENQUEUE_WAKEUP);
   2069	}
   2070
   2071	uclamp_rq_inc(rq, p);
   2072	p->sched_class->enqueue_task(rq, p, flags);
   2073
   2074	if (sched_core_enabled(rq))
   2075		sched_core_enqueue(rq, p);
   2076}
   2077
   2078static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
   2079{
   2080	if (sched_core_enabled(rq))
   2081		sched_core_dequeue(rq, p, flags);
   2082
   2083	if (!(flags & DEQUEUE_NOCLOCK))
   2084		update_rq_clock(rq);
   2085
   2086	if (!(flags & DEQUEUE_SAVE)) {
   2087		sched_info_dequeue(rq, p);
   2088		psi_dequeue(p, flags & DEQUEUE_SLEEP);
   2089	}
   2090
   2091	uclamp_rq_dec(rq, p);
   2092	p->sched_class->dequeue_task(rq, p, flags);
   2093}
   2094
   2095void activate_task(struct rq *rq, struct task_struct *p, int flags)
   2096{
   2097	enqueue_task(rq, p, flags);
   2098
   2099	p->on_rq = TASK_ON_RQ_QUEUED;
   2100}
   2101
   2102void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
   2103{
   2104	p->on_rq = (flags & DEQUEUE_SLEEP) ? 0 : TASK_ON_RQ_MIGRATING;
   2105
   2106	dequeue_task(rq, p, flags);
   2107}
   2108
   2109static inline int __normal_prio(int policy, int rt_prio, int nice)
   2110{
   2111	int prio;
   2112
   2113	if (dl_policy(policy))
   2114		prio = MAX_DL_PRIO - 1;
   2115	else if (rt_policy(policy))
   2116		prio = MAX_RT_PRIO - 1 - rt_prio;
   2117	else
   2118		prio = NICE_TO_PRIO(nice);
   2119
   2120	return prio;
   2121}
   2122
   2123/*
   2124 * Calculate the expected normal priority: i.e. priority
   2125 * without taking RT-inheritance into account. Might be
   2126 * boosted by interactivity modifiers. Changes upon fork,
   2127 * setprio syscalls, and whenever the interactivity
   2128 * estimator recalculates.
   2129 */
   2130static inline int normal_prio(struct task_struct *p)
   2131{
   2132	return __normal_prio(p->policy, p->rt_priority, PRIO_TO_NICE(p->static_prio));
   2133}
   2134
   2135/*
   2136 * Calculate the current priority, i.e. the priority
   2137 * taken into account by the scheduler. This value might
   2138 * be boosted by RT tasks, or might be boosted by
   2139 * interactivity modifiers. Will be RT if the task got
   2140 * RT-boosted. If not then it returns p->normal_prio.
   2141 */
   2142static int effective_prio(struct task_struct *p)
   2143{
   2144	p->normal_prio = normal_prio(p);
   2145	/*
   2146	 * If we are RT tasks or we were boosted to RT priority,
   2147	 * keep the priority unchanged. Otherwise, update priority
   2148	 * to the normal priority:
   2149	 */
   2150	if (!rt_prio(p->prio))
   2151		return p->normal_prio;
   2152	return p->prio;
   2153}
   2154
   2155/**
   2156 * task_curr - is this task currently executing on a CPU?
   2157 * @p: the task in question.
   2158 *
   2159 * Return: 1 if the task is currently executing. 0 otherwise.
   2160 */
   2161inline int task_curr(const struct task_struct *p)
   2162{
   2163	return cpu_curr(task_cpu(p)) == p;
   2164}
   2165
   2166/*
   2167 * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
   2168 * use the balance_callback list if you want balancing.
   2169 *
   2170 * this means any call to check_class_changed() must be followed by a call to
   2171 * balance_callback().
   2172 */
   2173static inline void check_class_changed(struct rq *rq, struct task_struct *p,
   2174				       const struct sched_class *prev_class,
   2175				       int oldprio)
   2176{
   2177	if (prev_class != p->sched_class) {
   2178		if (prev_class->switched_from)
   2179			prev_class->switched_from(rq, p);
   2180
   2181		p->sched_class->switched_to(rq, p);
   2182	} else if (oldprio != p->prio || dl_task(p))
   2183		p->sched_class->prio_changed(rq, p, oldprio);
   2184}
   2185
   2186void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
   2187{
   2188	if (p->sched_class == rq->curr->sched_class)
   2189		rq->curr->sched_class->check_preempt_curr(rq, p, flags);
   2190	else if (sched_class_above(p->sched_class, rq->curr->sched_class))
   2191		resched_curr(rq);
   2192
   2193	/*
   2194	 * A queue event has occurred, and we're going to schedule.  In
   2195	 * this case, we can save a useless back to back clock update.
   2196	 */
   2197	if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
   2198		rq_clock_skip_update(rq);
   2199}
   2200
   2201#ifdef CONFIG_SMP
   2202
   2203static void
   2204__do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask, u32 flags);
   2205
   2206static int __set_cpus_allowed_ptr(struct task_struct *p,
   2207				  const struct cpumask *new_mask,
   2208				  u32 flags);
   2209
   2210static void migrate_disable_switch(struct rq *rq, struct task_struct *p)
   2211{
   2212	if (likely(!p->migration_disabled))
   2213		return;
   2214
   2215	if (p->cpus_ptr != &p->cpus_mask)
   2216		return;
   2217
   2218	/*
   2219	 * Violates locking rules! see comment in __do_set_cpus_allowed().
   2220	 */
   2221	__do_set_cpus_allowed(p, cpumask_of(rq->cpu), SCA_MIGRATE_DISABLE);
   2222}
   2223
   2224void migrate_disable(void)
   2225{
   2226	struct task_struct *p = current;
   2227
   2228	if (p->migration_disabled) {
   2229		p->migration_disabled++;
   2230		return;
   2231	}
   2232
   2233	preempt_disable();
   2234	this_rq()->nr_pinned++;
   2235	p->migration_disabled = 1;
   2236	preempt_enable();
   2237}
   2238EXPORT_SYMBOL_GPL(migrate_disable);
   2239
   2240void migrate_enable(void)
   2241{
   2242	struct task_struct *p = current;
   2243
   2244	if (p->migration_disabled > 1) {
   2245		p->migration_disabled--;
   2246		return;
   2247	}
   2248
   2249	if (WARN_ON_ONCE(!p->migration_disabled))
   2250		return;
   2251
   2252	/*
   2253	 * Ensure stop_task runs either before or after this, and that
   2254	 * __set_cpus_allowed_ptr(SCA_MIGRATE_ENABLE) doesn't schedule().
   2255	 */
   2256	preempt_disable();
   2257	if (p->cpus_ptr != &p->cpus_mask)
   2258		__set_cpus_allowed_ptr(p, &p->cpus_mask, SCA_MIGRATE_ENABLE);
   2259	/*
   2260	 * Mustn't clear migration_disabled() until cpus_ptr points back at the
   2261	 * regular cpus_mask, otherwise things that race (eg.
   2262	 * select_fallback_rq) get confused.
   2263	 */
   2264	barrier();
   2265	p->migration_disabled = 0;
   2266	this_rq()->nr_pinned--;
   2267	preempt_enable();
   2268}
   2269EXPORT_SYMBOL_GPL(migrate_enable);
   2270
   2271static inline bool rq_has_pinned_tasks(struct rq *rq)
   2272{
   2273	return rq->nr_pinned;
   2274}
   2275
   2276/*
   2277 * Per-CPU kthreads are allowed to run on !active && online CPUs, see
   2278 * __set_cpus_allowed_ptr() and select_fallback_rq().
   2279 */
   2280static inline bool is_cpu_allowed(struct task_struct *p, int cpu)
   2281{
   2282	/* When not in the task's cpumask, no point in looking further. */
   2283	if (!cpumask_test_cpu(cpu, p->cpus_ptr))
   2284		return false;
   2285
   2286	/* migrate_disabled() must be allowed to finish. */
   2287	if (is_migration_disabled(p))
   2288		return cpu_online(cpu);
   2289
   2290	/* Non kernel threads are not allowed during either online or offline. */
   2291	if (!(p->flags & PF_KTHREAD))
   2292		return cpu_active(cpu) && task_cpu_possible(cpu, p);
   2293
   2294	/* KTHREAD_IS_PER_CPU is always allowed. */
   2295	if (kthread_is_per_cpu(p))
   2296		return cpu_online(cpu);
   2297
   2298	/* Regular kernel threads don't get to stay during offline. */
   2299	if (cpu_dying(cpu))
   2300		return false;
   2301
   2302	/* But are allowed during online. */
   2303	return cpu_online(cpu);
   2304}
   2305
   2306/*
   2307 * This is how migration works:
   2308 *
   2309 * 1) we invoke migration_cpu_stop() on the target CPU using
   2310 *    stop_one_cpu().
   2311 * 2) stopper starts to run (implicitly forcing the migrated thread
   2312 *    off the CPU)
   2313 * 3) it checks whether the migrated task is still in the wrong runqueue.
   2314 * 4) if it's in the wrong runqueue then the migration thread removes
   2315 *    it and puts it into the right queue.
   2316 * 5) stopper completes and stop_one_cpu() returns and the migration
   2317 *    is done.
   2318 */
   2319
   2320/*
   2321 * move_queued_task - move a queued task to new rq.
   2322 *
   2323 * Returns (locked) new rq. Old rq's lock is released.
   2324 */
   2325static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf,
   2326				   struct task_struct *p, int new_cpu)
   2327{
   2328	lockdep_assert_rq_held(rq);
   2329
   2330	deactivate_task(rq, p, DEQUEUE_NOCLOCK);
   2331	set_task_cpu(p, new_cpu);
   2332	rq_unlock(rq, rf);
   2333
   2334	rq = cpu_rq(new_cpu);
   2335
   2336	rq_lock(rq, rf);
   2337	BUG_ON(task_cpu(p) != new_cpu);
   2338	activate_task(rq, p, 0);
   2339	check_preempt_curr(rq, p, 0);
   2340
   2341	return rq;
   2342}
   2343
   2344struct migration_arg {
   2345	struct task_struct		*task;
   2346	int				dest_cpu;
   2347	struct set_affinity_pending	*pending;
   2348};
   2349
   2350/*
   2351 * @refs: number of wait_for_completion()
   2352 * @stop_pending: is @stop_work in use
   2353 */
   2354struct set_affinity_pending {
   2355	refcount_t		refs;
   2356	unsigned int		stop_pending;
   2357	struct completion	done;
   2358	struct cpu_stop_work	stop_work;
   2359	struct migration_arg	arg;
   2360};
   2361
   2362/*
   2363 * Move (not current) task off this CPU, onto the destination CPU. We're doing
   2364 * this because either it can't run here any more (set_cpus_allowed()
   2365 * away from this CPU, or CPU going down), or because we're
   2366 * attempting to rebalance this task on exec (sched_exec).
   2367 *
   2368 * So we race with normal scheduler movements, but that's OK, as long
   2369 * as the task is no longer on this CPU.
   2370 */
   2371static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,
   2372				 struct task_struct *p, int dest_cpu)
   2373{
   2374	/* Affinity changed (again). */
   2375	if (!is_cpu_allowed(p, dest_cpu))
   2376		return rq;
   2377
   2378	update_rq_clock(rq);
   2379	rq = move_queued_task(rq, rf, p, dest_cpu);
   2380
   2381	return rq;
   2382}
   2383
   2384/*
   2385 * migration_cpu_stop - this will be executed by a highprio stopper thread
   2386 * and performs thread migration by bumping thread off CPU then
   2387 * 'pushing' onto another runqueue.
   2388 */
   2389static int migration_cpu_stop(void *data)
   2390{
   2391	struct migration_arg *arg = data;
   2392	struct set_affinity_pending *pending = arg->pending;
   2393	struct task_struct *p = arg->task;
   2394	struct rq *rq = this_rq();
   2395	bool complete = false;
   2396	struct rq_flags rf;
   2397
   2398	/*
   2399	 * The original target CPU might have gone down and we might
   2400	 * be on another CPU but it doesn't matter.
   2401	 */
   2402	local_irq_save(rf.flags);
   2403	/*
   2404	 * We need to explicitly wake pending tasks before running
   2405	 * __migrate_task() such that we will not miss enforcing cpus_ptr
   2406	 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
   2407	 */
   2408	flush_smp_call_function_queue();
   2409
   2410	raw_spin_lock(&p->pi_lock);
   2411	rq_lock(rq, &rf);
   2412
   2413	/*
   2414	 * If we were passed a pending, then ->stop_pending was set, thus
   2415	 * p->migration_pending must have remained stable.
   2416	 */
   2417	WARN_ON_ONCE(pending && pending != p->migration_pending);
   2418
   2419	/*
   2420	 * If task_rq(p) != rq, it cannot be migrated here, because we're
   2421	 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
   2422	 * we're holding p->pi_lock.
   2423	 */
   2424	if (task_rq(p) == rq) {
   2425		if (is_migration_disabled(p))
   2426			goto out;
   2427
   2428		if (pending) {
   2429			p->migration_pending = NULL;
   2430			complete = true;
   2431
   2432			if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask))
   2433				goto out;
   2434		}
   2435
   2436		if (task_on_rq_queued(p))
   2437			rq = __migrate_task(rq, &rf, p, arg->dest_cpu);
   2438		else
   2439			p->wake_cpu = arg->dest_cpu;
   2440
   2441		/*
   2442		 * XXX __migrate_task() can fail, at which point we might end
   2443		 * up running on a dodgy CPU, AFAICT this can only happen
   2444		 * during CPU hotplug, at which point we'll get pushed out
   2445		 * anyway, so it's probably not a big deal.
   2446		 */
   2447
   2448	} else if (pending) {
   2449		/*
   2450		 * This happens when we get migrated between migrate_enable()'s
   2451		 * preempt_enable() and scheduling the stopper task. At that
   2452		 * point we're a regular task again and not current anymore.
   2453		 *
   2454		 * A !PREEMPT kernel has a giant hole here, which makes it far
   2455		 * more likely.
   2456		 */
   2457
   2458		/*
   2459		 * The task moved before the stopper got to run. We're holding
   2460		 * ->pi_lock, so the allowed mask is stable - if it got
   2461		 * somewhere allowed, we're done.
   2462		 */
   2463		if (cpumask_test_cpu(task_cpu(p), p->cpus_ptr)) {
   2464			p->migration_pending = NULL;
   2465			complete = true;
   2466			goto out;
   2467		}
   2468
   2469		/*
   2470		 * When migrate_enable() hits a rq mis-match we can't reliably
   2471		 * determine is_migration_disabled() and so have to chase after
   2472		 * it.
   2473		 */
   2474		WARN_ON_ONCE(!pending->stop_pending);
   2475		task_rq_unlock(rq, p, &rf);
   2476		stop_one_cpu_nowait(task_cpu(p), migration_cpu_stop,
   2477				    &pending->arg, &pending->stop_work);
   2478		return 0;
   2479	}
   2480out:
   2481	if (pending)
   2482		pending->stop_pending = false;
   2483	task_rq_unlock(rq, p, &rf);
   2484
   2485	if (complete)
   2486		complete_all(&pending->done);
   2487
   2488	return 0;
   2489}
   2490
   2491int push_cpu_stop(void *arg)
   2492{
   2493	struct rq *lowest_rq = NULL, *rq = this_rq();
   2494	struct task_struct *p = arg;
   2495
   2496	raw_spin_lock_irq(&p->pi_lock);
   2497	raw_spin_rq_lock(rq);
   2498
   2499	if (task_rq(p) != rq)
   2500		goto out_unlock;
   2501
   2502	if (is_migration_disabled(p)) {
   2503		p->migration_flags |= MDF_PUSH;
   2504		goto out_unlock;
   2505	}
   2506
   2507	p->migration_flags &= ~MDF_PUSH;
   2508
   2509	if (p->sched_class->find_lock_rq)
   2510		lowest_rq = p->sched_class->find_lock_rq(p, rq);
   2511
   2512	if (!lowest_rq)
   2513		goto out_unlock;
   2514
   2515	// XXX validate p is still the highest prio task
   2516	if (task_rq(p) == rq) {
   2517		deactivate_task(rq, p, 0);
   2518		set_task_cpu(p, lowest_rq->cpu);
   2519		activate_task(lowest_rq, p, 0);
   2520		resched_curr(lowest_rq);
   2521	}
   2522
   2523	double_unlock_balance(rq, lowest_rq);
   2524
   2525out_unlock:
   2526	rq->push_busy = false;
   2527	raw_spin_rq_unlock(rq);
   2528	raw_spin_unlock_irq(&p->pi_lock);
   2529
   2530	put_task_struct(p);
   2531	return 0;
   2532}
   2533
   2534/*
   2535 * sched_class::set_cpus_allowed must do the below, but is not required to
   2536 * actually call this function.
   2537 */
   2538void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask, u32 flags)
   2539{
   2540	if (flags & (SCA_MIGRATE_ENABLE | SCA_MIGRATE_DISABLE)) {
   2541		p->cpus_ptr = new_mask;
   2542		return;
   2543	}
   2544
   2545	cpumask_copy(&p->cpus_mask, new_mask);
   2546	p->nr_cpus_allowed = cpumask_weight(new_mask);
   2547}
   2548
   2549static void
   2550__do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask, u32 flags)
   2551{
   2552	struct rq *rq = task_rq(p);
   2553	bool queued, running;
   2554
   2555	/*
   2556	 * This here violates the locking rules for affinity, since we're only
   2557	 * supposed to change these variables while holding both rq->lock and
   2558	 * p->pi_lock.
   2559	 *
   2560	 * HOWEVER, it magically works, because ttwu() is the only code that
   2561	 * accesses these variables under p->pi_lock and only does so after
   2562	 * smp_cond_load_acquire(&p->on_cpu, !VAL), and we're in __schedule()
   2563	 * before finish_task().
   2564	 *
   2565	 * XXX do further audits, this smells like something putrid.
   2566	 */
   2567	if (flags & SCA_MIGRATE_DISABLE)
   2568		SCHED_WARN_ON(!p->on_cpu);
   2569	else
   2570		lockdep_assert_held(&p->pi_lock);
   2571
   2572	queued = task_on_rq_queued(p);
   2573	running = task_current(rq, p);
   2574
   2575	if (queued) {
   2576		/*
   2577		 * Because __kthread_bind() calls this on blocked tasks without
   2578		 * holding rq->lock.
   2579		 */
   2580		lockdep_assert_rq_held(rq);
   2581		dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
   2582	}
   2583	if (running)
   2584		put_prev_task(rq, p);
   2585
   2586	p->sched_class->set_cpus_allowed(p, new_mask, flags);
   2587
   2588	if (queued)
   2589		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
   2590	if (running)
   2591		set_next_task(rq, p);
   2592}
   2593
   2594void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
   2595{
   2596	__do_set_cpus_allowed(p, new_mask, 0);
   2597}
   2598
   2599int dup_user_cpus_ptr(struct task_struct *dst, struct task_struct *src,
   2600		      int node)
   2601{
   2602	if (!src->user_cpus_ptr)
   2603		return 0;
   2604
   2605	dst->user_cpus_ptr = kmalloc_node(cpumask_size(), GFP_KERNEL, node);
   2606	if (!dst->user_cpus_ptr)
   2607		return -ENOMEM;
   2608
   2609	cpumask_copy(dst->user_cpus_ptr, src->user_cpus_ptr);
   2610	return 0;
   2611}
   2612
   2613static inline struct cpumask *clear_user_cpus_ptr(struct task_struct *p)
   2614{
   2615	struct cpumask *user_mask = NULL;
   2616
   2617	swap(p->user_cpus_ptr, user_mask);
   2618
   2619	return user_mask;
   2620}
   2621
   2622void release_user_cpus_ptr(struct task_struct *p)
   2623{
   2624	kfree(clear_user_cpus_ptr(p));
   2625}
   2626
   2627/*
   2628 * This function is wildly self concurrent; here be dragons.
   2629 *
   2630 *
   2631 * When given a valid mask, __set_cpus_allowed_ptr() must block until the
   2632 * designated task is enqueued on an allowed CPU. If that task is currently
   2633 * running, we have to kick it out using the CPU stopper.
   2634 *
   2635 * Migrate-Disable comes along and tramples all over our nice sandcastle.
   2636 * Consider:
   2637 *
   2638 *     Initial conditions: P0->cpus_mask = [0, 1]
   2639 *
   2640 *     P0@CPU0                  P1
   2641 *
   2642 *     migrate_disable();
   2643 *     <preempted>
   2644 *                              set_cpus_allowed_ptr(P0, [1]);
   2645 *
   2646 * P1 *cannot* return from this set_cpus_allowed_ptr() call until P0 executes
   2647 * its outermost migrate_enable() (i.e. it exits its Migrate-Disable region).
   2648 * This means we need the following scheme:
   2649 *
   2650 *     P0@CPU0                  P1
   2651 *
   2652 *     migrate_disable();
   2653 *     <preempted>
   2654 *                              set_cpus_allowed_ptr(P0, [1]);
   2655 *                                <blocks>
   2656 *     <resumes>
   2657 *     migrate_enable();
   2658 *       __set_cpus_allowed_ptr();
   2659 *       <wakes local stopper>
   2660 *                         `--> <woken on migration completion>
   2661 *
   2662 * Now the fun stuff: there may be several P1-like tasks, i.e. multiple
   2663 * concurrent set_cpus_allowed_ptr(P0, [*]) calls. CPU affinity changes of any
   2664 * task p are serialized by p->pi_lock, which we can leverage: the one that
   2665 * should come into effect at the end of the Migrate-Disable region is the last
   2666 * one. This means we only need to track a single cpumask (i.e. p->cpus_mask),
   2667 * but we still need to properly signal those waiting tasks at the appropriate
   2668 * moment.
   2669 *
   2670 * This is implemented using struct set_affinity_pending. The first
   2671 * __set_cpus_allowed_ptr() caller within a given Migrate-Disable region will
   2672 * setup an instance of that struct and install it on the targeted task_struct.
   2673 * Any and all further callers will reuse that instance. Those then wait for
   2674 * a completion signaled at the tail of the CPU stopper callback (1), triggered
   2675 * on the end of the Migrate-Disable region (i.e. outermost migrate_enable()).
   2676 *
   2677 *
   2678 * (1) In the cases covered above. There is one more where the completion is
   2679 * signaled within affine_move_task() itself: when a subsequent affinity request
   2680 * occurs after the stopper bailed out due to the targeted task still being
   2681 * Migrate-Disable. Consider:
   2682 *
   2683 *     Initial conditions: P0->cpus_mask = [0, 1]
   2684 *
   2685 *     CPU0		  P1				P2
   2686 *     <P0>
   2687 *       migrate_disable();
   2688 *       <preempted>
   2689 *                        set_cpus_allowed_ptr(P0, [1]);
   2690 *                          <blocks>
   2691 *     <migration/0>
   2692 *       migration_cpu_stop()
   2693 *         is_migration_disabled()
   2694 *           <bails>
   2695 *                                                       set_cpus_allowed_ptr(P0, [0, 1]);
   2696 *                                                         <signal completion>
   2697 *                          <awakes>
   2698 *
   2699 * Note that the above is safe vs a concurrent migrate_enable(), as any
   2700 * pending affinity completion is preceded by an uninstallation of
   2701 * p->migration_pending done with p->pi_lock held.
   2702 */
   2703static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flags *rf,
   2704			    int dest_cpu, unsigned int flags)
   2705{
   2706	struct set_affinity_pending my_pending = { }, *pending = NULL;
   2707	bool stop_pending, complete = false;
   2708
   2709	/* Can the task run on the task's current CPU? If so, we're done */
   2710	if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) {
   2711		struct task_struct *push_task = NULL;
   2712
   2713		if ((flags & SCA_MIGRATE_ENABLE) &&
   2714		    (p->migration_flags & MDF_PUSH) && !rq->push_busy) {
   2715			rq->push_busy = true;
   2716			push_task = get_task_struct(p);
   2717		}
   2718
   2719		/*
   2720		 * If there are pending waiters, but no pending stop_work,
   2721		 * then complete now.
   2722		 */
   2723		pending = p->migration_pending;
   2724		if (pending && !pending->stop_pending) {
   2725			p->migration_pending = NULL;
   2726			complete = true;
   2727		}
   2728
   2729		task_rq_unlock(rq, p, rf);
   2730
   2731		if (push_task) {
   2732			stop_one_cpu_nowait(rq->cpu, push_cpu_stop,
   2733					    p, &rq->push_work);
   2734		}
   2735
   2736		if (complete)
   2737			complete_all(&pending->done);
   2738
   2739		return 0;
   2740	}
   2741
   2742	if (!(flags & SCA_MIGRATE_ENABLE)) {
   2743		/* serialized by p->pi_lock */
   2744		if (!p->migration_pending) {
   2745			/* Install the request */
   2746			refcount_set(&my_pending.refs, 1);
   2747			init_completion(&my_pending.done);
   2748			my_pending.arg = (struct migration_arg) {
   2749				.task = p,
   2750				.dest_cpu = dest_cpu,
   2751				.pending = &my_pending,
   2752			};
   2753
   2754			p->migration_pending = &my_pending;
   2755		} else {
   2756			pending = p->migration_pending;
   2757			refcount_inc(&pending->refs);
   2758			/*
   2759			 * Affinity has changed, but we've already installed a
   2760			 * pending. migration_cpu_stop() *must* see this, else
   2761			 * we risk a completion of the pending despite having a
   2762			 * task on a disallowed CPU.
   2763			 *
   2764			 * Serialized by p->pi_lock, so this is safe.
   2765			 */
   2766			pending->arg.dest_cpu = dest_cpu;
   2767		}
   2768	}
   2769	pending = p->migration_pending;
   2770	/*
   2771	 * - !MIGRATE_ENABLE:
   2772	 *   we'll have installed a pending if there wasn't one already.
   2773	 *
   2774	 * - MIGRATE_ENABLE:
   2775	 *   we're here because the current CPU isn't matching anymore,
   2776	 *   the only way that can happen is because of a concurrent
   2777	 *   set_cpus_allowed_ptr() call, which should then still be
   2778	 *   pending completion.
   2779	 *
   2780	 * Either way, we really should have a @pending here.
   2781	 */
   2782	if (WARN_ON_ONCE(!pending)) {
   2783		task_rq_unlock(rq, p, rf);
   2784		return -EINVAL;
   2785	}
   2786
   2787	if (task_running(rq, p) || READ_ONCE(p->__state) == TASK_WAKING) {
   2788		/*
   2789		 * MIGRATE_ENABLE gets here because 'p == current', but for
   2790		 * anything else we cannot do is_migration_disabled(), punt
   2791		 * and have the stopper function handle it all race-free.
   2792		 */
   2793		stop_pending = pending->stop_pending;
   2794		if (!stop_pending)
   2795			pending->stop_pending = true;
   2796
   2797		if (flags & SCA_MIGRATE_ENABLE)
   2798			p->migration_flags &= ~MDF_PUSH;
   2799
   2800		task_rq_unlock(rq, p, rf);
   2801
   2802		if (!stop_pending) {
   2803			stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop,
   2804					    &pending->arg, &pending->stop_work);
   2805		}
   2806
   2807		if (flags & SCA_MIGRATE_ENABLE)
   2808			return 0;
   2809	} else {
   2810
   2811		if (!is_migration_disabled(p)) {
   2812			if (task_on_rq_queued(p))
   2813				rq = move_queued_task(rq, rf, p, dest_cpu);
   2814
   2815			if (!pending->stop_pending) {
   2816				p->migration_pending = NULL;
   2817				complete = true;
   2818			}
   2819		}
   2820		task_rq_unlock(rq, p, rf);
   2821
   2822		if (complete)
   2823			complete_all(&pending->done);
   2824	}
   2825
   2826	wait_for_completion(&pending->done);
   2827
   2828	if (refcount_dec_and_test(&pending->refs))
   2829		wake_up_var(&pending->refs); /* No UaF, just an address */
   2830
   2831	/*
   2832	 * Block the original owner of &pending until all subsequent callers
   2833	 * have seen the completion and decremented the refcount
   2834	 */
   2835	wait_var_event(&my_pending.refs, !refcount_read(&my_pending.refs));
   2836
   2837	/* ARGH */
   2838	WARN_ON_ONCE(my_pending.stop_pending);
   2839
   2840	return 0;
   2841}
   2842
   2843/*
   2844 * Called with both p->pi_lock and rq->lock held; drops both before returning.
   2845 */
   2846static int __set_cpus_allowed_ptr_locked(struct task_struct *p,
   2847					 const struct cpumask *new_mask,
   2848					 u32 flags,
   2849					 struct rq *rq,
   2850					 struct rq_flags *rf)
   2851	__releases(rq->lock)
   2852	__releases(p->pi_lock)
   2853{
   2854	const struct cpumask *cpu_allowed_mask = task_cpu_possible_mask(p);
   2855	const struct cpumask *cpu_valid_mask = cpu_active_mask;
   2856	bool kthread = p->flags & PF_KTHREAD;
   2857	struct cpumask *user_mask = NULL;
   2858	unsigned int dest_cpu;
   2859	int ret = 0;
   2860
   2861	update_rq_clock(rq);
   2862
   2863	if (kthread || is_migration_disabled(p)) {
   2864		/*
   2865		 * Kernel threads are allowed on online && !active CPUs,
   2866		 * however, during cpu-hot-unplug, even these might get pushed
   2867		 * away if not KTHREAD_IS_PER_CPU.
   2868		 *
   2869		 * Specifically, migration_disabled() tasks must not fail the
   2870		 * cpumask_any_and_distribute() pick below, esp. so on
   2871		 * SCA_MIGRATE_ENABLE, otherwise we'll not call
   2872		 * set_cpus_allowed_common() and actually reset p->cpus_ptr.
   2873		 */
   2874		cpu_valid_mask = cpu_online_mask;
   2875	}
   2876
   2877	if (!kthread && !cpumask_subset(new_mask, cpu_allowed_mask)) {
   2878		ret = -EINVAL;
   2879		goto out;
   2880	}
   2881
   2882	/*
   2883	 * Must re-check here, to close a race against __kthread_bind(),
   2884	 * sched_setaffinity() is not guaranteed to observe the flag.
   2885	 */
   2886	if ((flags & SCA_CHECK) && (p->flags & PF_NO_SETAFFINITY)) {
   2887		ret = -EINVAL;
   2888		goto out;
   2889	}
   2890
   2891	if (!(flags & SCA_MIGRATE_ENABLE)) {
   2892		if (cpumask_equal(&p->cpus_mask, new_mask))
   2893			goto out;
   2894
   2895		if (WARN_ON_ONCE(p == current &&
   2896				 is_migration_disabled(p) &&
   2897				 !cpumask_test_cpu(task_cpu(p), new_mask))) {
   2898			ret = -EBUSY;
   2899			goto out;
   2900		}
   2901	}
   2902
   2903	/*
   2904	 * Picking a ~random cpu helps in cases where we are changing affinity
   2905	 * for groups of tasks (ie. cpuset), so that load balancing is not
   2906	 * immediately required to distribute the tasks within their new mask.
   2907	 */
   2908	dest_cpu = cpumask_any_and_distribute(cpu_valid_mask, new_mask);
   2909	if (dest_cpu >= nr_cpu_ids) {
   2910		ret = -EINVAL;
   2911		goto out;
   2912	}
   2913
   2914	__do_set_cpus_allowed(p, new_mask, flags);
   2915
   2916	if (flags & SCA_USER)
   2917		user_mask = clear_user_cpus_ptr(p);
   2918
   2919	ret = affine_move_task(rq, p, rf, dest_cpu, flags);
   2920
   2921	kfree(user_mask);
   2922
   2923	return ret;
   2924
   2925out:
   2926	task_rq_unlock(rq, p, rf);
   2927
   2928	return ret;
   2929}
   2930
   2931/*
   2932 * Change a given task's CPU affinity. Migrate the thread to a
   2933 * proper CPU and schedule it away if the CPU it's executing on
   2934 * is removed from the allowed bitmask.
   2935 *
   2936 * NOTE: the caller must have a valid reference to the task, the
   2937 * task must not exit() & deallocate itself prematurely. The
   2938 * call is not atomic; no spinlocks may be held.
   2939 */
   2940static int __set_cpus_allowed_ptr(struct task_struct *p,
   2941				  const struct cpumask *new_mask, u32 flags)
   2942{
   2943	struct rq_flags rf;
   2944	struct rq *rq;
   2945
   2946	rq = task_rq_lock(p, &rf);
   2947	return __set_cpus_allowed_ptr_locked(p, new_mask, flags, rq, &rf);
   2948}
   2949
   2950int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
   2951{
   2952	return __set_cpus_allowed_ptr(p, new_mask, 0);
   2953}
   2954EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
   2955
   2956/*
   2957 * Change a given task's CPU affinity to the intersection of its current
   2958 * affinity mask and @subset_mask, writing the resulting mask to @new_mask
   2959 * and pointing @p->user_cpus_ptr to a copy of the old mask.
   2960 * If the resulting mask is empty, leave the affinity unchanged and return
   2961 * -EINVAL.
   2962 */
   2963static int restrict_cpus_allowed_ptr(struct task_struct *p,
   2964				     struct cpumask *new_mask,
   2965				     const struct cpumask *subset_mask)
   2966{
   2967	struct cpumask *user_mask = NULL;
   2968	struct rq_flags rf;
   2969	struct rq *rq;
   2970	int err;
   2971
   2972	if (!p->user_cpus_ptr) {
   2973		user_mask = kmalloc(cpumask_size(), GFP_KERNEL);
   2974		if (!user_mask)
   2975			return -ENOMEM;
   2976	}
   2977
   2978	rq = task_rq_lock(p, &rf);
   2979
   2980	/*
   2981	 * Forcefully restricting the affinity of a deadline task is
   2982	 * likely to cause problems, so fail and noisily override the
   2983	 * mask entirely.
   2984	 */
   2985	if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
   2986		err = -EPERM;
   2987		goto err_unlock;
   2988	}
   2989
   2990	if (!cpumask_and(new_mask, &p->cpus_mask, subset_mask)) {
   2991		err = -EINVAL;
   2992		goto err_unlock;
   2993	}
   2994
   2995	/*
   2996	 * We're about to butcher the task affinity, so keep track of what
   2997	 * the user asked for in case we're able to restore it later on.
   2998	 */
   2999	if (user_mask) {
   3000		cpumask_copy(user_mask, p->cpus_ptr);
   3001		p->user_cpus_ptr = user_mask;
   3002	}
   3003
   3004	return __set_cpus_allowed_ptr_locked(p, new_mask, 0, rq, &rf);
   3005
   3006err_unlock:
   3007	task_rq_unlock(rq, p, &rf);
   3008	kfree(user_mask);
   3009	return err;
   3010}
   3011
   3012/*
   3013 * Restrict the CPU affinity of task @p so that it is a subset of
   3014 * task_cpu_possible_mask() and point @p->user_cpu_ptr to a copy of the
   3015 * old affinity mask. If the resulting mask is empty, we warn and walk
   3016 * up the cpuset hierarchy until we find a suitable mask.
   3017 */
   3018void force_compatible_cpus_allowed_ptr(struct task_struct *p)
   3019{
   3020	cpumask_var_t new_mask;
   3021	const struct cpumask *override_mask = task_cpu_possible_mask(p);
   3022
   3023	alloc_cpumask_var(&new_mask, GFP_KERNEL);
   3024
   3025	/*
   3026	 * __migrate_task() can fail silently in the face of concurrent
   3027	 * offlining of the chosen destination CPU, so take the hotplug
   3028	 * lock to ensure that the migration succeeds.
   3029	 */
   3030	cpus_read_lock();
   3031	if (!cpumask_available(new_mask))
   3032		goto out_set_mask;
   3033
   3034	if (!restrict_cpus_allowed_ptr(p, new_mask, override_mask))
   3035		goto out_free_mask;
   3036
   3037	/*
   3038	 * We failed to find a valid subset of the affinity mask for the
   3039	 * task, so override it based on its cpuset hierarchy.
   3040	 */
   3041	cpuset_cpus_allowed(p, new_mask);
   3042	override_mask = new_mask;
   3043
   3044out_set_mask:
   3045	if (printk_ratelimit()) {
   3046		printk_deferred("Overriding affinity for process %d (%s) to CPUs %*pbl\n",
   3047				task_pid_nr(p), p->comm,
   3048				cpumask_pr_args(override_mask));
   3049	}
   3050
   3051	WARN_ON(set_cpus_allowed_ptr(p, override_mask));
   3052out_free_mask:
   3053	cpus_read_unlock();
   3054	free_cpumask_var(new_mask);
   3055}
   3056
   3057static int
   3058__sched_setaffinity(struct task_struct *p, const struct cpumask *mask);
   3059
   3060/*
   3061 * Restore the affinity of a task @p which was previously restricted by a
   3062 * call to force_compatible_cpus_allowed_ptr(). This will clear (and free)
   3063 * @p->user_cpus_ptr.
   3064 *
   3065 * It is the caller's responsibility to serialise this with any calls to
   3066 * force_compatible_cpus_allowed_ptr(@p).
   3067 */
   3068void relax_compatible_cpus_allowed_ptr(struct task_struct *p)
   3069{
   3070	struct cpumask *user_mask = p->user_cpus_ptr;
   3071	unsigned long flags;
   3072
   3073	/*
   3074	 * Try to restore the old affinity mask. If this fails, then
   3075	 * we free the mask explicitly to avoid it being inherited across
   3076	 * a subsequent fork().
   3077	 */
   3078	if (!user_mask || !__sched_setaffinity(p, user_mask))
   3079		return;
   3080
   3081	raw_spin_lock_irqsave(&p->pi_lock, flags);
   3082	user_mask = clear_user_cpus_ptr(p);
   3083	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
   3084
   3085	kfree(user_mask);
   3086}
   3087
   3088void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
   3089{
   3090#ifdef CONFIG_SCHED_DEBUG
   3091	unsigned int state = READ_ONCE(p->__state);
   3092
   3093	/*
   3094	 * We should never call set_task_cpu() on a blocked task,
   3095	 * ttwu() will sort out the placement.
   3096	 */
   3097	WARN_ON_ONCE(state != TASK_RUNNING && state != TASK_WAKING && !p->on_rq);
   3098
   3099	/*
   3100	 * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
   3101	 * because schedstat_wait_{start,end} rebase migrating task's wait_start
   3102	 * time relying on p->on_rq.
   3103	 */
   3104	WARN_ON_ONCE(state == TASK_RUNNING &&
   3105		     p->sched_class == &fair_sched_class &&
   3106		     (p->on_rq && !task_on_rq_migrating(p)));
   3107
   3108#ifdef CONFIG_LOCKDEP
   3109	/*
   3110	 * The caller should hold either p->pi_lock or rq->lock, when changing
   3111	 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
   3112	 *
   3113	 * sched_move_task() holds both and thus holding either pins the cgroup,
   3114	 * see task_group().
   3115	 *
   3116	 * Furthermore, all task_rq users should acquire both locks, see
   3117	 * task_rq_lock().
   3118	 */
   3119	WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
   3120				      lockdep_is_held(__rq_lockp(task_rq(p)))));
   3121#endif
   3122	/*
   3123	 * Clearly, migrating tasks to offline CPUs is a fairly daft thing.
   3124	 */
   3125	WARN_ON_ONCE(!cpu_online(new_cpu));
   3126
   3127	WARN_ON_ONCE(is_migration_disabled(p));
   3128#endif
   3129
   3130	trace_sched_migrate_task(p, new_cpu);
   3131
   3132	if (task_cpu(p) != new_cpu) {
   3133		if (p->sched_class->migrate_task_rq)
   3134			p->sched_class->migrate_task_rq(p, new_cpu);
   3135		p->se.nr_migrations++;
   3136		rseq_migrate(p);
   3137		perf_event_task_migrate(p);
   3138	}
   3139
   3140	__set_task_cpu(p, new_cpu);
   3141}
   3142
   3143#ifdef CONFIG_NUMA_BALANCING
   3144static void __migrate_swap_task(struct task_struct *p, int cpu)
   3145{
   3146	if (task_on_rq_queued(p)) {
   3147		struct rq *src_rq, *dst_rq;
   3148		struct rq_flags srf, drf;
   3149
   3150		src_rq = task_rq(p);
   3151		dst_rq = cpu_rq(cpu);
   3152
   3153		rq_pin_lock(src_rq, &srf);
   3154		rq_pin_lock(dst_rq, &drf);
   3155
   3156		deactivate_task(src_rq, p, 0);
   3157		set_task_cpu(p, cpu);
   3158		activate_task(dst_rq, p, 0);
   3159		check_preempt_curr(dst_rq, p, 0);
   3160
   3161		rq_unpin_lock(dst_rq, &drf);
   3162		rq_unpin_lock(src_rq, &srf);
   3163
   3164	} else {
   3165		/*
   3166		 * Task isn't running anymore; make it appear like we migrated
   3167		 * it before it went to sleep. This means on wakeup we make the
   3168		 * previous CPU our target instead of where it really is.
   3169		 */
   3170		p->wake_cpu = cpu;
   3171	}
   3172}
   3173
   3174struct migration_swap_arg {
   3175	struct task_struct *src_task, *dst_task;
   3176	int src_cpu, dst_cpu;
   3177};
   3178
   3179static int migrate_swap_stop(void *data)
   3180{
   3181	struct migration_swap_arg *arg = data;
   3182	struct rq *src_rq, *dst_rq;
   3183	int ret = -EAGAIN;
   3184
   3185	if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
   3186		return -EAGAIN;
   3187
   3188	src_rq = cpu_rq(arg->src_cpu);
   3189	dst_rq = cpu_rq(arg->dst_cpu);
   3190
   3191	double_raw_lock(&arg->src_task->pi_lock,
   3192			&arg->dst_task->pi_lock);
   3193	double_rq_lock(src_rq, dst_rq);
   3194
   3195	if (task_cpu(arg->dst_task) != arg->dst_cpu)
   3196		goto unlock;
   3197
   3198	if (task_cpu(arg->src_task) != arg->src_cpu)
   3199		goto unlock;
   3200
   3201	if (!cpumask_test_cpu(arg->dst_cpu, arg->src_task->cpus_ptr))
   3202		goto unlock;
   3203
   3204	if (!cpumask_test_cpu(arg->src_cpu, arg->dst_task->cpus_ptr))
   3205		goto unlock;
   3206
   3207	__migrate_swap_task(arg->src_task, arg->dst_cpu);
   3208	__migrate_swap_task(arg->dst_task, arg->src_cpu);
   3209
   3210	ret = 0;
   3211
   3212unlock:
   3213	double_rq_unlock(src_rq, dst_rq);
   3214	raw_spin_unlock(&arg->dst_task->pi_lock);
   3215	raw_spin_unlock(&arg->src_task->pi_lock);
   3216
   3217	return ret;
   3218}
   3219
   3220/*
   3221 * Cross migrate two tasks
   3222 */
   3223int migrate_swap(struct task_struct *cur, struct task_struct *p,
   3224		int target_cpu, int curr_cpu)
   3225{
   3226	struct migration_swap_arg arg;
   3227	int ret = -EINVAL;
   3228
   3229	arg = (struct migration_swap_arg){
   3230		.src_task = cur,
   3231		.src_cpu = curr_cpu,
   3232		.dst_task = p,
   3233		.dst_cpu = target_cpu,
   3234	};
   3235
   3236	if (arg.src_cpu == arg.dst_cpu)
   3237		goto out;
   3238
   3239	/*
   3240	 * These three tests are all lockless; this is OK since all of them
   3241	 * will be re-checked with proper locks held further down the line.
   3242	 */
   3243	if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
   3244		goto out;
   3245
   3246	if (!cpumask_test_cpu(arg.dst_cpu, arg.src_task->cpus_ptr))
   3247		goto out;
   3248
   3249	if (!cpumask_test_cpu(arg.src_cpu, arg.dst_task->cpus_ptr))
   3250		goto out;
   3251
   3252	trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
   3253	ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
   3254
   3255out:
   3256	return ret;
   3257}
   3258#endif /* CONFIG_NUMA_BALANCING */
   3259
   3260/*
   3261 * wait_task_inactive - wait for a thread to unschedule.
   3262 *
   3263 * If @match_state is nonzero, it's the @p->state value just checked and
   3264 * not expected to change.  If it changes, i.e. @p might have woken up,
   3265 * then return zero.  When we succeed in waiting for @p to be off its CPU,
   3266 * we return a positive number (its total switch count).  If a second call
   3267 * a short while later returns the same number, the caller can be sure that
   3268 * @p has remained unscheduled the whole time.
   3269 *
   3270 * The caller must ensure that the task *will* unschedule sometime soon,
   3271 * else this function might spin for a *long* time. This function can't
   3272 * be called with interrupts off, or it may introduce deadlock with
   3273 * smp_call_function() if an IPI is sent by the same process we are
   3274 * waiting to become inactive.
   3275 */
   3276unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state)
   3277{
   3278	int running, queued;
   3279	struct rq_flags rf;
   3280	unsigned long ncsw;
   3281	struct rq *rq;
   3282
   3283	for (;;) {
   3284		/*
   3285		 * We do the initial early heuristics without holding
   3286		 * any task-queue locks at all. We'll only try to get
   3287		 * the runqueue lock when things look like they will
   3288		 * work out!
   3289		 */
   3290		rq = task_rq(p);
   3291
   3292		/*
   3293		 * If the task is actively running on another CPU
   3294		 * still, just relax and busy-wait without holding
   3295		 * any locks.
   3296		 *
   3297		 * NOTE! Since we don't hold any locks, it's not
   3298		 * even sure that "rq" stays as the right runqueue!
   3299		 * But we don't care, since "task_running()" will
   3300		 * return false if the runqueue has changed and p
   3301		 * is actually now running somewhere else!
   3302		 */
   3303		while (task_running(rq, p)) {
   3304			if (match_state && unlikely(READ_ONCE(p->__state) != match_state))
   3305				return 0;
   3306			cpu_relax();
   3307		}
   3308
   3309		/*
   3310		 * Ok, time to look more closely! We need the rq
   3311		 * lock now, to be *sure*. If we're wrong, we'll
   3312		 * just go back and repeat.
   3313		 */
   3314		rq = task_rq_lock(p, &rf);
   3315		trace_sched_wait_task(p);
   3316		running = task_running(rq, p);
   3317		queued = task_on_rq_queued(p);
   3318		ncsw = 0;
   3319		if (!match_state || READ_ONCE(p->__state) == match_state)
   3320			ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
   3321		task_rq_unlock(rq, p, &rf);
   3322
   3323		/*
   3324		 * If it changed from the expected state, bail out now.
   3325		 */
   3326		if (unlikely(!ncsw))
   3327			break;
   3328
   3329		/*
   3330		 * Was it really running after all now that we
   3331		 * checked with the proper locks actually held?
   3332		 *
   3333		 * Oops. Go back and try again..
   3334		 */
   3335		if (unlikely(running)) {
   3336			cpu_relax();
   3337			continue;
   3338		}
   3339
   3340		/*
   3341		 * It's not enough that it's not actively running,
   3342		 * it must be off the runqueue _entirely_, and not
   3343		 * preempted!
   3344		 *
   3345		 * So if it was still runnable (but just not actively
   3346		 * running right now), it's preempted, and we should
   3347		 * yield - it could be a while.
   3348		 */
   3349		if (unlikely(queued)) {
   3350			ktime_t to = NSEC_PER_SEC / HZ;
   3351
   3352			set_current_state(TASK_UNINTERRUPTIBLE);
   3353			schedule_hrtimeout(&to, HRTIMER_MODE_REL_HARD);
   3354			continue;
   3355		}
   3356
   3357		/*
   3358		 * Ahh, all good. It wasn't running, and it wasn't
   3359		 * runnable, which means that it will never become
   3360		 * running in the future either. We're all done!
   3361		 */
   3362		break;
   3363	}
   3364
   3365	return ncsw;
   3366}
   3367
   3368/***
   3369 * kick_process - kick a running thread to enter/exit the kernel
   3370 * @p: the to-be-kicked thread
   3371 *
   3372 * Cause a process which is running on another CPU to enter
   3373 * kernel-mode, without any delay. (to get signals handled.)
   3374 *
   3375 * NOTE: this function doesn't have to take the runqueue lock,
   3376 * because all it wants to ensure is that the remote task enters
   3377 * the kernel. If the IPI races and the task has been migrated
   3378 * to another CPU then no harm is done and the purpose has been
   3379 * achieved as well.
   3380 */
   3381void kick_process(struct task_struct *p)
   3382{
   3383	int cpu;
   3384
   3385	preempt_disable();
   3386	cpu = task_cpu(p);
   3387	if ((cpu != smp_processor_id()) && task_curr(p))
   3388		smp_send_reschedule(cpu);
   3389	preempt_enable();
   3390}
   3391EXPORT_SYMBOL_GPL(kick_process);
   3392
   3393/*
   3394 * ->cpus_ptr is protected by both rq->lock and p->pi_lock
   3395 *
   3396 * A few notes on cpu_active vs cpu_online:
   3397 *
   3398 *  - cpu_active must be a subset of cpu_online
   3399 *
   3400 *  - on CPU-up we allow per-CPU kthreads on the online && !active CPU,
   3401 *    see __set_cpus_allowed_ptr(). At this point the newly online
   3402 *    CPU isn't yet part of the sched domains, and balancing will not
   3403 *    see it.
   3404 *
   3405 *  - on CPU-down we clear cpu_active() to mask the sched domains and
   3406 *    avoid the load balancer to place new tasks on the to be removed
   3407 *    CPU. Existing tasks will remain running there and will be taken
   3408 *    off.
   3409 *
   3410 * This means that fallback selection must not select !active CPUs.
   3411 * And can assume that any active CPU must be online. Conversely
   3412 * select_task_rq() below may allow selection of !active CPUs in order
   3413 * to satisfy the above rules.
   3414 */
   3415static int select_fallback_rq(int cpu, struct task_struct *p)
   3416{
   3417	int nid = cpu_to_node(cpu);
   3418	const struct cpumask *nodemask = NULL;
   3419	enum { cpuset, possible, fail } state = cpuset;
   3420	int dest_cpu;
   3421
   3422	/*
   3423	 * If the node that the CPU is on has been offlined, cpu_to_node()
   3424	 * will return -1. There is no CPU on the node, and we should
   3425	 * select the CPU on the other node.
   3426	 */
   3427	if (nid != -1) {
   3428		nodemask = cpumask_of_node(nid);
   3429
   3430		/* Look for allowed, online CPU in same node. */
   3431		for_each_cpu(dest_cpu, nodemask) {
   3432			if (is_cpu_allowed(p, dest_cpu))
   3433				return dest_cpu;
   3434		}
   3435	}
   3436
   3437	for (;;) {
   3438		/* Any allowed, online CPU? */
   3439		for_each_cpu(dest_cpu, p->cpus_ptr) {
   3440			if (!is_cpu_allowed(p, dest_cpu))
   3441				continue;
   3442
   3443			goto out;
   3444		}
   3445
   3446		/* No more Mr. Nice Guy. */
   3447		switch (state) {
   3448		case cpuset:
   3449			if (cpuset_cpus_allowed_fallback(p)) {
   3450				state = possible;
   3451				break;
   3452			}
   3453			fallthrough;
   3454		case possible:
   3455			/*
   3456			 * XXX When called from select_task_rq() we only
   3457			 * hold p->pi_lock and again violate locking order.
   3458			 *
   3459			 * More yuck to audit.
   3460			 */
   3461			do_set_cpus_allowed(p, task_cpu_possible_mask(p));
   3462			state = fail;
   3463			break;
   3464		case fail:
   3465			BUG();
   3466			break;
   3467		}
   3468	}
   3469
   3470out:
   3471	if (state != cpuset) {
   3472		/*
   3473		 * Don't tell them about moving exiting tasks or
   3474		 * kernel threads (both mm NULL), since they never
   3475		 * leave kernel.
   3476		 */
   3477		if (p->mm && printk_ratelimit()) {
   3478			printk_deferred("process %d (%s) no longer affine to cpu%d\n",
   3479					task_pid_nr(p), p->comm, cpu);
   3480		}
   3481	}
   3482
   3483	return dest_cpu;
   3484}
   3485
   3486/*
   3487 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_ptr is stable.
   3488 */
   3489static inline
   3490int select_task_rq(struct task_struct *p, int cpu, int wake_flags)
   3491{
   3492	lockdep_assert_held(&p->pi_lock);
   3493
   3494	if (p->nr_cpus_allowed > 1 && !is_migration_disabled(p))
   3495		cpu = p->sched_class->select_task_rq(p, cpu, wake_flags);
   3496	else
   3497		cpu = cpumask_any(p->cpus_ptr);
   3498
   3499	/*
   3500	 * In order not to call set_task_cpu() on a blocking task we need
   3501	 * to rely on ttwu() to place the task on a valid ->cpus_ptr
   3502	 * CPU.
   3503	 *
   3504	 * Since this is common to all placement strategies, this lives here.
   3505	 *
   3506	 * [ this allows ->select_task() to simply return task_cpu(p) and
   3507	 *   not worry about this generic constraint ]
   3508	 */
   3509	if (unlikely(!is_cpu_allowed(p, cpu)))
   3510		cpu = select_fallback_rq(task_cpu(p), p);
   3511
   3512	return cpu;
   3513}
   3514
   3515void sched_set_stop_task(int cpu, struct task_struct *stop)
   3516{
   3517	static struct lock_class_key stop_pi_lock;
   3518	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
   3519	struct task_struct *old_stop = cpu_rq(cpu)->stop;
   3520
   3521	if (stop) {
   3522		/*
   3523		 * Make it appear like a SCHED_FIFO task, its something
   3524		 * userspace knows about and won't get confused about.
   3525		 *
   3526		 * Also, it will make PI more or less work without too
   3527		 * much confusion -- but then, stop work should not
   3528		 * rely on PI working anyway.
   3529		 */
   3530		sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
   3531
   3532		stop->sched_class = &stop_sched_class;
   3533
   3534		/*
   3535		 * The PI code calls rt_mutex_setprio() with ->pi_lock held to
   3536		 * adjust the effective priority of a task. As a result,
   3537		 * rt_mutex_setprio() can trigger (RT) balancing operations,
   3538		 * which can then trigger wakeups of the stop thread to push
   3539		 * around the current task.
   3540		 *
   3541		 * The stop task itself will never be part of the PI-chain, it
   3542		 * never blocks, therefore that ->pi_lock recursion is safe.
   3543		 * Tell lockdep about this by placing the stop->pi_lock in its
   3544		 * own class.
   3545		 */
   3546		lockdep_set_class(&stop->pi_lock, &stop_pi_lock);
   3547	}
   3548
   3549	cpu_rq(cpu)->stop = stop;
   3550
   3551	if (old_stop) {
   3552		/*
   3553		 * Reset it back to a normal scheduling class so that
   3554		 * it can die in pieces.
   3555		 */
   3556		old_stop->sched_class = &rt_sched_class;
   3557	}
   3558}
   3559
   3560#else /* CONFIG_SMP */
   3561
   3562static inline int __set_cpus_allowed_ptr(struct task_struct *p,
   3563					 const struct cpumask *new_mask,
   3564					 u32 flags)
   3565{
   3566	return set_cpus_allowed_ptr(p, new_mask);
   3567}
   3568
   3569static inline void migrate_disable_switch(struct rq *rq, struct task_struct *p) { }
   3570
   3571static inline bool rq_has_pinned_tasks(struct rq *rq)
   3572{
   3573	return false;
   3574}
   3575
   3576#endif /* !CONFIG_SMP */
   3577
   3578static void
   3579ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
   3580{
   3581	struct rq *rq;
   3582
   3583	if (!schedstat_enabled())
   3584		return;
   3585
   3586	rq = this_rq();
   3587
   3588#ifdef CONFIG_SMP
   3589	if (cpu == rq->cpu) {
   3590		__schedstat_inc(rq->ttwu_local);
   3591		__schedstat_inc(p->stats.nr_wakeups_local);
   3592	} else {
   3593		struct sched_domain *sd;
   3594
   3595		__schedstat_inc(p->stats.nr_wakeups_remote);
   3596		rcu_read_lock();
   3597		for_each_domain(rq->cpu, sd) {
   3598			if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
   3599				__schedstat_inc(sd->ttwu_wake_remote);
   3600				break;
   3601			}
   3602		}
   3603		rcu_read_unlock();
   3604	}
   3605
   3606	if (wake_flags & WF_MIGRATED)
   3607		__schedstat_inc(p->stats.nr_wakeups_migrate);
   3608#endif /* CONFIG_SMP */
   3609
   3610	__schedstat_inc(rq->ttwu_count);
   3611	__schedstat_inc(p->stats.nr_wakeups);
   3612
   3613	if (wake_flags & WF_SYNC)
   3614		__schedstat_inc(p->stats.nr_wakeups_sync);
   3615}
   3616
   3617/*
   3618 * Mark the task runnable and perform wakeup-preemption.
   3619 */
   3620static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags,
   3621			   struct rq_flags *rf)
   3622{
   3623	check_preempt_curr(rq, p, wake_flags);
   3624	WRITE_ONCE(p->__state, TASK_RUNNING);
   3625	trace_sched_wakeup(p);
   3626
   3627#ifdef CONFIG_SMP
   3628	if (p->sched_class->task_woken) {
   3629		/*
   3630		 * Our task @p is fully woken up and running; so it's safe to
   3631		 * drop the rq->lock, hereafter rq is only used for statistics.
   3632		 */
   3633		rq_unpin_lock(rq, rf);
   3634		p->sched_class->task_woken(rq, p);
   3635		rq_repin_lock(rq, rf);
   3636	}
   3637
   3638	if (rq->idle_stamp) {
   3639		u64 delta = rq_clock(rq) - rq->idle_stamp;
   3640		u64 max = 2*rq->max_idle_balance_cost;
   3641
   3642		update_avg(&rq->avg_idle, delta);
   3643
   3644		if (rq->avg_idle > max)
   3645			rq->avg_idle = max;
   3646
   3647		rq->wake_stamp = jiffies;
   3648		rq->wake_avg_idle = rq->avg_idle / 2;
   3649
   3650		rq->idle_stamp = 0;
   3651	}
   3652#endif
   3653}
   3654
   3655static void
   3656ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
   3657		 struct rq_flags *rf)
   3658{
   3659	int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK;
   3660
   3661	lockdep_assert_rq_held(rq);
   3662
   3663	if (p->sched_contributes_to_load)
   3664		rq->nr_uninterruptible--;
   3665
   3666#ifdef CONFIG_SMP
   3667	if (wake_flags & WF_MIGRATED)
   3668		en_flags |= ENQUEUE_MIGRATED;
   3669	else
   3670#endif
   3671	if (p->in_iowait) {
   3672		delayacct_blkio_end(p);
   3673		atomic_dec(&task_rq(p)->nr_iowait);
   3674	}
   3675
   3676	activate_task(rq, p, en_flags);
   3677	ttwu_do_wakeup(rq, p, wake_flags, rf);
   3678}
   3679
   3680/*
   3681 * Consider @p being inside a wait loop:
   3682 *
   3683 *   for (;;) {
   3684 *      set_current_state(TASK_UNINTERRUPTIBLE);
   3685 *
   3686 *      if (CONDITION)
   3687 *         break;
   3688 *
   3689 *      schedule();
   3690 *   }
   3691 *   __set_current_state(TASK_RUNNING);
   3692 *
   3693 * between set_current_state() and schedule(). In this case @p is still
   3694 * runnable, so all that needs doing is change p->state back to TASK_RUNNING in
   3695 * an atomic manner.
   3696 *
   3697 * By taking task_rq(p)->lock we serialize against schedule(), if @p->on_rq
   3698 * then schedule() must still happen and p->state can be changed to
   3699 * TASK_RUNNING. Otherwise we lost the race, schedule() has happened, and we
   3700 * need to do a full wakeup with enqueue.
   3701 *
   3702 * Returns: %true when the wakeup is done,
   3703 *          %false otherwise.
   3704 */
   3705static int ttwu_runnable(struct task_struct *p, int wake_flags)
   3706{
   3707	struct rq_flags rf;
   3708	struct rq *rq;
   3709	int ret = 0;
   3710
   3711	rq = __task_rq_lock(p, &rf);
   3712	if (task_on_rq_queued(p)) {
   3713		/* check_preempt_curr() may use rq clock */
   3714		update_rq_clock(rq);
   3715		ttwu_do_wakeup(rq, p, wake_flags, &rf);
   3716		ret = 1;
   3717	}
   3718	__task_rq_unlock(rq, &rf);
   3719
   3720	return ret;
   3721}
   3722
   3723#ifdef CONFIG_SMP
   3724void sched_ttwu_pending(void *arg)
   3725{
   3726	struct llist_node *llist = arg;
   3727	struct rq *rq = this_rq();
   3728	struct task_struct *p, *t;
   3729	struct rq_flags rf;
   3730
   3731	if (!llist)
   3732		return;
   3733
   3734	/*
   3735	 * rq::ttwu_pending racy indication of out-standing wakeups.
   3736	 * Races such that false-negatives are possible, since they
   3737	 * are shorter lived that false-positives would be.
   3738	 */
   3739	WRITE_ONCE(rq->ttwu_pending, 0);
   3740
   3741	rq_lock_irqsave(rq, &rf);
   3742	update_rq_clock(rq);
   3743
   3744	llist_for_each_entry_safe(p, t, llist, wake_entry.llist) {
   3745		if (WARN_ON_ONCE(p->on_cpu))
   3746			smp_cond_load_acquire(&p->on_cpu, !VAL);
   3747
   3748		if (WARN_ON_ONCE(task_cpu(p) != cpu_of(rq)))
   3749			set_task_cpu(p, cpu_of(rq));
   3750
   3751		ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf);
   3752	}
   3753
   3754	rq_unlock_irqrestore(rq, &rf);
   3755}
   3756
   3757void send_call_function_single_ipi(int cpu)
   3758{
   3759	struct rq *rq = cpu_rq(cpu);
   3760
   3761	if (!set_nr_if_polling(rq->idle))
   3762		arch_send_call_function_single_ipi(cpu);
   3763	else
   3764		trace_sched_wake_idle_without_ipi(cpu);
   3765}
   3766
   3767/*
   3768 * Queue a task on the target CPUs wake_list and wake the CPU via IPI if
   3769 * necessary. The wakee CPU on receipt of the IPI will queue the task
   3770 * via sched_ttwu_wakeup() for activation so the wakee incurs the cost
   3771 * of the wakeup instead of the waker.
   3772 */
   3773static void __ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
   3774{
   3775	struct rq *rq = cpu_rq(cpu);
   3776
   3777	p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
   3778
   3779	WRITE_ONCE(rq->ttwu_pending, 1);
   3780	__smp_call_single_queue(cpu, &p->wake_entry.llist);
   3781}
   3782
   3783void wake_up_if_idle(int cpu)
   3784{
   3785	struct rq *rq = cpu_rq(cpu);
   3786	struct rq_flags rf;
   3787
   3788	rcu_read_lock();
   3789
   3790	if (!is_idle_task(rcu_dereference(rq->curr)))
   3791		goto out;
   3792
   3793	rq_lock_irqsave(rq, &rf);
   3794	if (is_idle_task(rq->curr))
   3795		resched_curr(rq);
   3796	/* Else CPU is not idle, do nothing here: */
   3797	rq_unlock_irqrestore(rq, &rf);
   3798
   3799out:
   3800	rcu_read_unlock();
   3801}
   3802
   3803bool cpus_share_cache(int this_cpu, int that_cpu)
   3804{
   3805	if (this_cpu == that_cpu)
   3806		return true;
   3807
   3808	return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
   3809}
   3810
   3811static inline bool ttwu_queue_cond(int cpu, int wake_flags)
   3812{
   3813	/*
   3814	 * Do not complicate things with the async wake_list while the CPU is
   3815	 * in hotplug state.
   3816	 */
   3817	if (!cpu_active(cpu))
   3818		return false;
   3819
   3820	/*
   3821	 * If the CPU does not share cache, then queue the task on the
   3822	 * remote rqs wakelist to avoid accessing remote data.
   3823	 */
   3824	if (!cpus_share_cache(smp_processor_id(), cpu))
   3825		return true;
   3826
   3827	/*
   3828	 * If the task is descheduling and the only running task on the
   3829	 * CPU then use the wakelist to offload the task activation to
   3830	 * the soon-to-be-idle CPU as the current CPU is likely busy.
   3831	 * nr_running is checked to avoid unnecessary task stacking.
   3832	 */
   3833	if ((wake_flags & WF_ON_CPU) && cpu_rq(cpu)->nr_running <= 1)
   3834		return true;
   3835
   3836	return false;
   3837}
   3838
   3839static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
   3840{
   3841	if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu, wake_flags)) {
   3842		if (WARN_ON_ONCE(cpu == smp_processor_id()))
   3843			return false;
   3844
   3845		sched_clock_cpu(cpu); /* Sync clocks across CPUs */
   3846		__ttwu_queue_wakelist(p, cpu, wake_flags);
   3847		return true;
   3848	}
   3849
   3850	return false;
   3851}
   3852
   3853#else /* !CONFIG_SMP */
   3854
   3855static inline bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
   3856{
   3857	return false;
   3858}
   3859
   3860#endif /* CONFIG_SMP */
   3861
   3862static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
   3863{
   3864	struct rq *rq = cpu_rq(cpu);
   3865	struct rq_flags rf;
   3866
   3867	if (ttwu_queue_wakelist(p, cpu, wake_flags))
   3868		return;
   3869
   3870	rq_lock(rq, &rf);
   3871	update_rq_clock(rq);
   3872	ttwu_do_activate(rq, p, wake_flags, &rf);
   3873	rq_unlock(rq, &rf);
   3874}
   3875
   3876/*
   3877 * Invoked from try_to_wake_up() to check whether the task can be woken up.
   3878 *
   3879 * The caller holds p::pi_lock if p != current or has preemption
   3880 * disabled when p == current.
   3881 *
   3882 * The rules of PREEMPT_RT saved_state:
   3883 *
   3884 *   The related locking code always holds p::pi_lock when updating
   3885 *   p::saved_state, which means the code is fully serialized in both cases.
   3886 *
   3887 *   The lock wait and lock wakeups happen via TASK_RTLOCK_WAIT. No other
   3888 *   bits set. This allows to distinguish all wakeup scenarios.
   3889 */
   3890static __always_inline
   3891bool ttwu_state_match(struct task_struct *p, unsigned int state, int *success)
   3892{
   3893	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)) {
   3894		WARN_ON_ONCE((state & TASK_RTLOCK_WAIT) &&
   3895			     state != TASK_RTLOCK_WAIT);
   3896	}
   3897
   3898	if (READ_ONCE(p->__state) & state) {
   3899		*success = 1;
   3900		return true;
   3901	}
   3902
   3903#ifdef CONFIG_PREEMPT_RT
   3904	/*
   3905	 * Saved state preserves the task state across blocking on
   3906	 * an RT lock.  If the state matches, set p::saved_state to
   3907	 * TASK_RUNNING, but do not wake the task because it waits
   3908	 * for a lock wakeup. Also indicate success because from
   3909	 * the regular waker's point of view this has succeeded.
   3910	 *
   3911	 * After acquiring the lock the task will restore p::__state
   3912	 * from p::saved_state which ensures that the regular
   3913	 * wakeup is not lost. The restore will also set
   3914	 * p::saved_state to TASK_RUNNING so any further tests will
   3915	 * not result in false positives vs. @success
   3916	 */
   3917	if (p->saved_state & state) {
   3918		p->saved_state = TASK_RUNNING;
   3919		*success = 1;
   3920	}
   3921#endif
   3922	return false;
   3923}
   3924
   3925/*
   3926 * Notes on Program-Order guarantees on SMP systems.
   3927 *
   3928 *  MIGRATION
   3929 *
   3930 * The basic program-order guarantee on SMP systems is that when a task [t]
   3931 * migrates, all its activity on its old CPU [c0] happens-before any subsequent
   3932 * execution on its new CPU [c1].
   3933 *
   3934 * For migration (of runnable tasks) this is provided by the following means:
   3935 *
   3936 *  A) UNLOCK of the rq(c0)->lock scheduling out task t
   3937 *  B) migration for t is required to synchronize *both* rq(c0)->lock and
   3938 *     rq(c1)->lock (if not at the same time, then in that order).
   3939 *  C) LOCK of the rq(c1)->lock scheduling in task
   3940 *
   3941 * Release/acquire chaining guarantees that B happens after A and C after B.
   3942 * Note: the CPU doing B need not be c0 or c1
   3943 *
   3944 * Example:
   3945 *
   3946 *   CPU0            CPU1            CPU2
   3947 *
   3948 *   LOCK rq(0)->lock
   3949 *   sched-out X
   3950 *   sched-in Y
   3951 *   UNLOCK rq(0)->lock
   3952 *
   3953 *                                   LOCK rq(0)->lock // orders against CPU0
   3954 *                                   dequeue X
   3955 *                                   UNLOCK rq(0)->lock
   3956 *
   3957 *                                   LOCK rq(1)->lock
   3958 *                                   enqueue X
   3959 *                                   UNLOCK rq(1)->lock
   3960 *
   3961 *                   LOCK rq(1)->lock // orders against CPU2
   3962 *                   sched-out Z
   3963 *                   sched-in X
   3964 *                   UNLOCK rq(1)->lock
   3965 *
   3966 *
   3967 *  BLOCKING -- aka. SLEEP + WAKEUP
   3968 *
   3969 * For blocking we (obviously) need to provide the same guarantee as for
   3970 * migration. However the means are completely different as there is no lock
   3971 * chain to provide order. Instead we do:
   3972 *
   3973 *   1) smp_store_release(X->on_cpu, 0)   -- finish_task()
   3974 *   2) smp_cond_load_acquire(!X->on_cpu) -- try_to_wake_up()
   3975 *
   3976 * Example:
   3977 *
   3978 *   CPU0 (schedule)  CPU1 (try_to_wake_up) CPU2 (schedule)
   3979 *
   3980 *   LOCK rq(0)->lock LOCK X->pi_lock
   3981 *   dequeue X
   3982 *   sched-out X
   3983 *   smp_store_release(X->on_cpu, 0);
   3984 *
   3985 *                    smp_cond_load_acquire(&X->on_cpu, !VAL);
   3986 *                    X->state = WAKING
   3987 *                    set_task_cpu(X,2)
   3988 *
   3989 *                    LOCK rq(2)->lock
   3990 *                    enqueue X
   3991 *                    X->state = RUNNING
   3992 *                    UNLOCK rq(2)->lock
   3993 *
   3994 *                                          LOCK rq(2)->lock // orders against CPU1
   3995 *                                          sched-out Z
   3996 *                                          sched-in X
   3997 *                                          UNLOCK rq(2)->lock
   3998 *
   3999 *                    UNLOCK X->pi_lock
   4000 *   UNLOCK rq(0)->lock
   4001 *
   4002 *
   4003 * However, for wakeups there is a second guarantee we must provide, namely we
   4004 * must ensure that CONDITION=1 done by the caller can not be reordered with
   4005 * accesses to the task state; see try_to_wake_up() and set_current_state().
   4006 */
   4007
   4008/**
   4009 * try_to_wake_up - wake up a thread
   4010 * @p: the thread to be awakened
   4011 * @state: the mask of task states that can be woken
   4012 * @wake_flags: wake modifier flags (WF_*)
   4013 *
   4014 * Conceptually does:
   4015 *
   4016 *   If (@state & @p->state) @p->state = TASK_RUNNING.
   4017 *
   4018 * If the task was not queued/runnable, also place it back on a runqueue.
   4019 *
   4020 * This function is atomic against schedule() which would dequeue the task.
   4021 *
   4022 * It issues a full memory barrier before accessing @p->state, see the comment
   4023 * with set_current_state().
   4024 *
   4025 * Uses p->pi_lock to serialize against concurrent wake-ups.
   4026 *
   4027 * Relies on p->pi_lock stabilizing:
   4028 *  - p->sched_class
   4029 *  - p->cpus_ptr
   4030 *  - p->sched_task_group
   4031 * in order to do migration, see its use of select_task_rq()/set_task_cpu().
   4032 *
   4033 * Tries really hard to only take one task_rq(p)->lock for performance.
   4034 * Takes rq->lock in:
   4035 *  - ttwu_runnable()    -- old rq, unavoidable, see comment there;
   4036 *  - ttwu_queue()       -- new rq, for enqueue of the task;
   4037 *  - psi_ttwu_dequeue() -- much sadness :-( accounting will kill us.
   4038 *
   4039 * As a consequence we race really badly with just about everything. See the
   4040 * many memory barriers and their comments for details.
   4041 *
   4042 * Return: %true if @p->state changes (an actual wakeup was done),
   4043 *	   %false otherwise.
   4044 */
   4045static int
   4046try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
   4047{
   4048	unsigned long flags;
   4049	int cpu, success = 0;
   4050
   4051	preempt_disable();
   4052	if (p == current) {
   4053		/*
   4054		 * We're waking current, this means 'p->on_rq' and 'task_cpu(p)
   4055		 * == smp_processor_id()'. Together this means we can special
   4056		 * case the whole 'p->on_rq && ttwu_runnable()' case below
   4057		 * without taking any locks.
   4058		 *
   4059		 * In particular:
   4060		 *  - we rely on Program-Order guarantees for all the ordering,
   4061		 *  - we're serialized against set_special_state() by virtue of
   4062		 *    it disabling IRQs (this allows not taking ->pi_lock).
   4063		 */
   4064		if (!ttwu_state_match(p, state, &success))
   4065			goto out;
   4066
   4067		trace_sched_waking(p);
   4068		WRITE_ONCE(p->__state, TASK_RUNNING);
   4069		trace_sched_wakeup(p);
   4070		goto out;
   4071	}
   4072
   4073	/*
   4074	 * If we are going to wake up a thread waiting for CONDITION we
   4075	 * need to ensure that CONDITION=1 done by the caller can not be
   4076	 * reordered with p->state check below. This pairs with smp_store_mb()
   4077	 * in set_current_state() that the waiting thread does.
   4078	 */
   4079	raw_spin_lock_irqsave(&p->pi_lock, flags);
   4080	smp_mb__after_spinlock();
   4081	if (!ttwu_state_match(p, state, &success))
   4082		goto unlock;
   4083
   4084	trace_sched_waking(p);
   4085
   4086	/*
   4087	 * Ensure we load p->on_rq _after_ p->state, otherwise it would
   4088	 * be possible to, falsely, observe p->on_rq == 0 and get stuck
   4089	 * in smp_cond_load_acquire() below.
   4090	 *
   4091	 * sched_ttwu_pending()			try_to_wake_up()
   4092	 *   STORE p->on_rq = 1			  LOAD p->state
   4093	 *   UNLOCK rq->lock
   4094	 *
   4095	 * __schedule() (switch to task 'p')
   4096	 *   LOCK rq->lock			  smp_rmb();
   4097	 *   smp_mb__after_spinlock();
   4098	 *   UNLOCK rq->lock
   4099	 *
   4100	 * [task p]
   4101	 *   STORE p->state = UNINTERRUPTIBLE	  LOAD p->on_rq
   4102	 *
   4103	 * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
   4104	 * __schedule().  See the comment for smp_mb__after_spinlock().
   4105	 *
   4106	 * A similar smb_rmb() lives in try_invoke_on_locked_down_task().
   4107	 */
   4108	smp_rmb();
   4109	if (READ_ONCE(p->on_rq) && ttwu_runnable(p, wake_flags))
   4110		goto unlock;
   4111
   4112#ifdef CONFIG_SMP
   4113	/*
   4114	 * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
   4115	 * possible to, falsely, observe p->on_cpu == 0.
   4116	 *
   4117	 * One must be running (->on_cpu == 1) in order to remove oneself
   4118	 * from the runqueue.
   4119	 *
   4120	 * __schedule() (switch to task 'p')	try_to_wake_up()
   4121	 *   STORE p->on_cpu = 1		  LOAD p->on_rq
   4122	 *   UNLOCK rq->lock
   4123	 *
   4124	 * __schedule() (put 'p' to sleep)
   4125	 *   LOCK rq->lock			  smp_rmb();
   4126	 *   smp_mb__after_spinlock();
   4127	 *   STORE p->on_rq = 0			  LOAD p->on_cpu
   4128	 *
   4129	 * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
   4130	 * __schedule().  See the comment for smp_mb__after_spinlock().
   4131	 *
   4132	 * Form a control-dep-acquire with p->on_rq == 0 above, to ensure
   4133	 * schedule()'s deactivate_task() has 'happened' and p will no longer
   4134	 * care about it's own p->state. See the comment in __schedule().
   4135	 */
   4136	smp_acquire__after_ctrl_dep();
   4137
   4138	/*
   4139	 * We're doing the wakeup (@success == 1), they did a dequeue (p->on_rq
   4140	 * == 0), which means we need to do an enqueue, change p->state to
   4141	 * TASK_WAKING such that we can unlock p->pi_lock before doing the
   4142	 * enqueue, such as ttwu_queue_wakelist().
   4143	 */
   4144	WRITE_ONCE(p->__state, TASK_WAKING);
   4145
   4146	/*
   4147	 * If the owning (remote) CPU is still in the middle of schedule() with
   4148	 * this task as prev, considering queueing p on the remote CPUs wake_list
   4149	 * which potentially sends an IPI instead of spinning on p->on_cpu to
   4150	 * let the waker make forward progress. This is safe because IRQs are
   4151	 * disabled and the IPI will deliver after on_cpu is cleared.
   4152	 *
   4153	 * Ensure we load task_cpu(p) after p->on_cpu:
   4154	 *
   4155	 * set_task_cpu(p, cpu);
   4156	 *   STORE p->cpu = @cpu
   4157	 * __schedule() (switch to task 'p')
   4158	 *   LOCK rq->lock
   4159	 *   smp_mb__after_spin_lock()		smp_cond_load_acquire(&p->on_cpu)
   4160	 *   STORE p->on_cpu = 1		LOAD p->cpu
   4161	 *
   4162	 * to ensure we observe the correct CPU on which the task is currently
   4163	 * scheduling.
   4164	 */
   4165	if (smp_load_acquire(&p->on_cpu) &&
   4166	    ttwu_queue_wakelist(p, task_cpu(p), wake_flags | WF_ON_CPU))
   4167		goto unlock;
   4168
   4169	/*
   4170	 * If the owning (remote) CPU is still in the middle of schedule() with
   4171	 * this task as prev, wait until it's done referencing the task.
   4172	 *
   4173	 * Pairs with the smp_store_release() in finish_task().
   4174	 *
   4175	 * This ensures that tasks getting woken will be fully ordered against
   4176	 * their previous state and preserve Program Order.
   4177	 */
   4178	smp_cond_load_acquire(&p->on_cpu, !VAL);
   4179
   4180	cpu = select_task_rq(p, p->wake_cpu, wake_flags | WF_TTWU);
   4181	if (task_cpu(p) != cpu) {
   4182		if (p->in_iowait) {
   4183			delayacct_blkio_end(p);
   4184			atomic_dec(&task_rq(p)->nr_iowait);
   4185		}
   4186
   4187		wake_flags |= WF_MIGRATED;
   4188		psi_ttwu_dequeue(p);
   4189		set_task_cpu(p, cpu);
   4190	}
   4191#else
   4192	cpu = task_cpu(p);
   4193#endif /* CONFIG_SMP */
   4194
   4195	ttwu_queue(p, cpu, wake_flags);
   4196unlock:
   4197	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
   4198out:
   4199	if (success)
   4200		ttwu_stat(p, task_cpu(p), wake_flags);
   4201	preempt_enable();
   4202
   4203	return success;
   4204}
   4205
   4206/**
   4207 * task_call_func - Invoke a function on task in fixed state
   4208 * @p: Process for which the function is to be invoked, can be @current.
   4209 * @func: Function to invoke.
   4210 * @arg: Argument to function.
   4211 *
   4212 * Fix the task in it's current state by avoiding wakeups and or rq operations
   4213 * and call @func(@arg) on it.  This function can use ->on_rq and task_curr()
   4214 * to work out what the state is, if required.  Given that @func can be invoked
   4215 * with a runqueue lock held, it had better be quite lightweight.
   4216 *
   4217 * Returns:
   4218 *   Whatever @func returns
   4219 */
   4220int task_call_func(struct task_struct *p, task_call_f func, void *arg)
   4221{
   4222	struct rq *rq = NULL;
   4223	unsigned int state;
   4224	struct rq_flags rf;
   4225	int ret;
   4226
   4227	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
   4228
   4229	state = READ_ONCE(p->__state);
   4230
   4231	/*
   4232	 * Ensure we load p->on_rq after p->__state, otherwise it would be
   4233	 * possible to, falsely, observe p->on_rq == 0.
   4234	 *
   4235	 * See try_to_wake_up() for a longer comment.
   4236	 */
   4237	smp_rmb();
   4238
   4239	/*
   4240	 * Since pi->lock blocks try_to_wake_up(), we don't need rq->lock when
   4241	 * the task is blocked. Make sure to check @state since ttwu() can drop
   4242	 * locks at the end, see ttwu_queue_wakelist().
   4243	 */
   4244	if (state == TASK_RUNNING || state == TASK_WAKING || p->on_rq)
   4245		rq = __task_rq_lock(p, &rf);
   4246
   4247	/*
   4248	 * At this point the task is pinned; either:
   4249	 *  - blocked and we're holding off wakeups	 (pi->lock)
   4250	 *  - woken, and we're holding off enqueue	 (rq->lock)
   4251	 *  - queued, and we're holding off schedule	 (rq->lock)
   4252	 *  - running, and we're holding off de-schedule (rq->lock)
   4253	 *
   4254	 * The called function (@func) can use: task_curr(), p->on_rq and
   4255	 * p->__state to differentiate between these states.
   4256	 */
   4257	ret = func(p, arg);
   4258
   4259	if (rq)
   4260		rq_unlock(rq, &rf);
   4261
   4262	raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags);
   4263	return ret;
   4264}
   4265
   4266/**
   4267 * wake_up_process - Wake up a specific process
   4268 * @p: The process to be woken up.
   4269 *
   4270 * Attempt to wake up the nominated process and move it to the set of runnable
   4271 * processes.
   4272 *
   4273 * Return: 1 if the process was woken up, 0 if it was already running.
   4274 *
   4275 * This function executes a full memory barrier before accessing the task state.
   4276 */
   4277int wake_up_process(struct task_struct *p)
   4278{
   4279	return try_to_wake_up(p, TASK_NORMAL, 0);
   4280}
   4281EXPORT_SYMBOL(wake_up_process);
   4282
   4283int wake_up_state(struct task_struct *p, unsigned int state)
   4284{
   4285	return try_to_wake_up(p, state, 0);
   4286}
   4287
   4288/*
   4289 * Perform scheduler related setup for a newly forked process p.
   4290 * p is forked by current.
   4291 *
   4292 * __sched_fork() is basic setup used by init_idle() too:
   4293 */
   4294static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
   4295{
   4296	p->on_rq			= 0;
   4297
   4298	p->se.on_rq			= 0;
   4299	p->se.exec_start		= 0;
   4300	p->se.sum_exec_runtime		= 0;
   4301	p->se.prev_sum_exec_runtime	= 0;
   4302	p->se.nr_migrations		= 0;
   4303	p->se.vruntime			= 0;
   4304	INIT_LIST_HEAD(&p->se.group_node);
   4305
   4306#ifdef CONFIG_FAIR_GROUP_SCHED
   4307	p->se.cfs_rq			= NULL;
   4308#endif
   4309
   4310#ifdef CONFIG_SCHEDSTATS
   4311	/* Even if schedstat is disabled, there should not be garbage */
   4312	memset(&p->stats, 0, sizeof(p->stats));
   4313#endif
   4314
   4315	RB_CLEAR_NODE(&p->dl.rb_node);
   4316	init_dl_task_timer(&p->dl);
   4317	init_dl_inactive_task_timer(&p->dl);
   4318	__dl_clear_params(p);
   4319
   4320	INIT_LIST_HEAD(&p->rt.run_list);
   4321	p->rt.timeout		= 0;
   4322	p->rt.time_slice	= sched_rr_timeslice;
   4323	p->rt.on_rq		= 0;
   4324	p->rt.on_list		= 0;
   4325
   4326#ifdef CONFIG_PREEMPT_NOTIFIERS
   4327	INIT_HLIST_HEAD(&p->preempt_notifiers);
   4328#endif
   4329
   4330#ifdef CONFIG_COMPACTION
   4331	p->capture_control = NULL;
   4332#endif
   4333	init_numa_balancing(clone_flags, p);
   4334#ifdef CONFIG_SMP
   4335	p->wake_entry.u_flags = CSD_TYPE_TTWU;
   4336	p->migration_pending = NULL;
   4337#endif
   4338}
   4339
   4340DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
   4341
   4342#ifdef CONFIG_NUMA_BALANCING
   4343
   4344int sysctl_numa_balancing_mode;
   4345
   4346static void __set_numabalancing_state(bool enabled)
   4347{
   4348	if (enabled)
   4349		static_branch_enable(&sched_numa_balancing);
   4350	else
   4351		static_branch_disable(&sched_numa_balancing);
   4352}
   4353
   4354void set_numabalancing_state(bool enabled)
   4355{
   4356	if (enabled)
   4357		sysctl_numa_balancing_mode = NUMA_BALANCING_NORMAL;
   4358	else
   4359		sysctl_numa_balancing_mode = NUMA_BALANCING_DISABLED;
   4360	__set_numabalancing_state(enabled);
   4361}
   4362
   4363#ifdef CONFIG_PROC_SYSCTL
   4364int sysctl_numa_balancing(struct ctl_table *table, int write,
   4365			  void *buffer, size_t *lenp, loff_t *ppos)
   4366{
   4367	struct ctl_table t;
   4368	int err;
   4369	int state = sysctl_numa_balancing_mode;
   4370
   4371	if (write && !capable(CAP_SYS_ADMIN))
   4372		return -EPERM;
   4373
   4374	t = *table;
   4375	t.data = &state;
   4376	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
   4377	if (err < 0)
   4378		return err;
   4379	if (write) {
   4380		sysctl_numa_balancing_mode = state;
   4381		__set_numabalancing_state(state);
   4382	}
   4383	return err;
   4384}
   4385#endif
   4386#endif
   4387
   4388#ifdef CONFIG_SCHEDSTATS
   4389
   4390DEFINE_STATIC_KEY_FALSE(sched_schedstats);
   4391
   4392static void set_schedstats(bool enabled)
   4393{
   4394	if (enabled)
   4395		static_branch_enable(&sched_schedstats);
   4396	else
   4397		static_branch_disable(&sched_schedstats);
   4398}
   4399
   4400void force_schedstat_enabled(void)
   4401{
   4402	if (!schedstat_enabled()) {
   4403		pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
   4404		static_branch_enable(&sched_schedstats);
   4405	}
   4406}
   4407
   4408static int __init setup_schedstats(char *str)
   4409{
   4410	int ret = 0;
   4411	if (!str)
   4412		goto out;
   4413
   4414	if (!strcmp(str, "enable")) {
   4415		set_schedstats(true);
   4416		ret = 1;
   4417	} else if (!strcmp(str, "disable")) {
   4418		set_schedstats(false);
   4419		ret = 1;
   4420	}
   4421out:
   4422	if (!ret)
   4423		pr_warn("Unable to parse schedstats=\n");
   4424
   4425	return ret;
   4426}
   4427__setup("schedstats=", setup_schedstats);
   4428
   4429#ifdef CONFIG_PROC_SYSCTL
   4430static int sysctl_schedstats(struct ctl_table *table, int write, void *buffer,
   4431		size_t *lenp, loff_t *ppos)
   4432{
   4433	struct ctl_table t;
   4434	int err;
   4435	int state = static_branch_likely(&sched_schedstats);
   4436
   4437	if (write && !capable(CAP_SYS_ADMIN))
   4438		return -EPERM;
   4439
   4440	t = *table;
   4441	t.data = &state;
   4442	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
   4443	if (err < 0)
   4444		return err;
   4445	if (write)
   4446		set_schedstats(state);
   4447	return err;
   4448}
   4449#endif /* CONFIG_PROC_SYSCTL */
   4450#endif /* CONFIG_SCHEDSTATS */
   4451
   4452#ifdef CONFIG_SYSCTL
   4453static struct ctl_table sched_core_sysctls[] = {
   4454#ifdef CONFIG_SCHEDSTATS
   4455	{
   4456		.procname       = "sched_schedstats",
   4457		.data           = NULL,
   4458		.maxlen         = sizeof(unsigned int),
   4459		.mode           = 0644,
   4460		.proc_handler   = sysctl_schedstats,
   4461		.extra1         = SYSCTL_ZERO,
   4462		.extra2         = SYSCTL_ONE,
   4463	},
   4464#endif /* CONFIG_SCHEDSTATS */
   4465#ifdef CONFIG_UCLAMP_TASK
   4466	{
   4467		.procname       = "sched_util_clamp_min",
   4468		.data           = &sysctl_sched_uclamp_util_min,
   4469		.maxlen         = sizeof(unsigned int),
   4470		.mode           = 0644,
   4471		.proc_handler   = sysctl_sched_uclamp_handler,
   4472	},
   4473	{
   4474		.procname       = "sched_util_clamp_max",
   4475		.data           = &sysctl_sched_uclamp_util_max,
   4476		.maxlen         = sizeof(unsigned int),
   4477		.mode           = 0644,
   4478		.proc_handler   = sysctl_sched_uclamp_handler,
   4479	},
   4480	{
   4481		.procname       = "sched_util_clamp_min_rt_default",
   4482		.data           = &sysctl_sched_uclamp_util_min_rt_default,
   4483		.maxlen         = sizeof(unsigned int),
   4484		.mode           = 0644,
   4485		.proc_handler   = sysctl_sched_uclamp_handler,
   4486	},
   4487#endif /* CONFIG_UCLAMP_TASK */
   4488	{}
   4489};
   4490static int __init sched_core_sysctl_init(void)
   4491{
   4492	register_sysctl_init("kernel", sched_core_sysctls);
   4493	return 0;
   4494}
   4495late_initcall(sched_core_sysctl_init);
   4496#endif /* CONFIG_SYSCTL */
   4497
   4498/*
   4499 * fork()/clone()-time setup:
   4500 */
   4501int sched_fork(unsigned long clone_flags, struct task_struct *p)
   4502{
   4503	__sched_fork(clone_flags, p);
   4504	/*
   4505	 * We mark the process as NEW here. This guarantees that
   4506	 * nobody will actually run it, and a signal or other external
   4507	 * event cannot wake it up and insert it on the runqueue either.
   4508	 */
   4509	p->__state = TASK_NEW;
   4510
   4511	/*
   4512	 * Make sure we do not leak PI boosting priority to the child.
   4513	 */
   4514	p->prio = current->normal_prio;
   4515
   4516	uclamp_fork(p);
   4517
   4518	/*
   4519	 * Revert to default priority/policy on fork if requested.
   4520	 */
   4521	if (unlikely(p->sched_reset_on_fork)) {
   4522		if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
   4523			p->policy = SCHED_NORMAL;
   4524			p->static_prio = NICE_TO_PRIO(0);
   4525			p->rt_priority = 0;
   4526		} else if (PRIO_TO_NICE(p->static_prio) < 0)
   4527			p->static_prio = NICE_TO_PRIO(0);
   4528
   4529		p->prio = p->normal_prio = p->static_prio;
   4530		set_load_weight(p, false);
   4531
   4532		/*
   4533		 * We don't need the reset flag anymore after the fork. It has
   4534		 * fulfilled its duty:
   4535		 */
   4536		p->sched_reset_on_fork = 0;
   4537	}
   4538
   4539	if (dl_prio(p->prio))
   4540		return -EAGAIN;
   4541	else if (rt_prio(p->prio))
   4542		p->sched_class = &rt_sched_class;
   4543	else
   4544		p->sched_class = &fair_sched_class;
   4545
   4546	init_entity_runnable_average(&p->se);
   4547
   4548
   4549#ifdef CONFIG_SCHED_INFO
   4550	if (likely(sched_info_on()))
   4551		memset(&p->sched_info, 0, sizeof(p->sched_info));
   4552#endif
   4553#if defined(CONFIG_SMP)
   4554	p->on_cpu = 0;
   4555#endif
   4556	init_task_preempt_count(p);
   4557#ifdef CONFIG_SMP
   4558	plist_node_init(&p->pushable_tasks, MAX_PRIO);
   4559	RB_CLEAR_NODE(&p->pushable_dl_tasks);
   4560#endif
   4561	return 0;
   4562}
   4563
   4564void sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs)
   4565{
   4566	unsigned long flags;
   4567
   4568	/*
   4569	 * Because we're not yet on the pid-hash, p->pi_lock isn't strictly
   4570	 * required yet, but lockdep gets upset if rules are violated.
   4571	 */
   4572	raw_spin_lock_irqsave(&p->pi_lock, flags);
   4573#ifdef CONFIG_CGROUP_SCHED
   4574	if (1) {
   4575		struct task_group *tg;
   4576		tg = container_of(kargs->cset->subsys[cpu_cgrp_id],
   4577				  struct task_group, css);
   4578		tg = autogroup_task_group(p, tg);
   4579		p->sched_task_group = tg;
   4580	}
   4581#endif
   4582	rseq_migrate(p);
   4583	/*
   4584	 * We're setting the CPU for the first time, we don't migrate,
   4585	 * so use __set_task_cpu().
   4586	 */
   4587	__set_task_cpu(p, smp_processor_id());
   4588	if (p->sched_class->task_fork)
   4589		p->sched_class->task_fork(p);
   4590	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
   4591}
   4592
   4593void sched_post_fork(struct task_struct *p)
   4594{
   4595	uclamp_post_fork(p);
   4596}
   4597
   4598unsigned long to_ratio(u64 period, u64 runtime)
   4599{
   4600	if (runtime == RUNTIME_INF)
   4601		return BW_UNIT;
   4602
   4603	/*
   4604	 * Doing this here saves a lot of checks in all
   4605	 * the calling paths, and returning zero seems
   4606	 * safe for them anyway.
   4607	 */
   4608	if (period == 0)
   4609		return 0;
   4610
   4611	return div64_u64(runtime << BW_SHIFT, period);
   4612}
   4613
   4614/*
   4615 * wake_up_new_task - wake up a newly created task for the first time.
   4616 *
   4617 * This function will do some initial scheduler statistics housekeeping
   4618 * that must be done for every newly created context, then puts the task
   4619 * on the runqueue and wakes it.
   4620 */
   4621void wake_up_new_task(struct task_struct *p)
   4622{
   4623	struct rq_flags rf;
   4624	struct rq *rq;
   4625
   4626	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
   4627	WRITE_ONCE(p->__state, TASK_RUNNING);
   4628#ifdef CONFIG_SMP
   4629	/*
   4630	 * Fork balancing, do it here and not earlier because:
   4631	 *  - cpus_ptr can change in the fork path
   4632	 *  - any previously selected CPU might disappear through hotplug
   4633	 *
   4634	 * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq,
   4635	 * as we're not fully set-up yet.
   4636	 */
   4637	p->recent_used_cpu = task_cpu(p);
   4638	rseq_migrate(p);
   4639	__set_task_cpu(p, select_task_rq(p, task_cpu(p), WF_FORK));
   4640#endif
   4641	rq = __task_rq_lock(p, &rf);
   4642	update_rq_clock(rq);
   4643	post_init_entity_util_avg(p);
   4644
   4645	activate_task(rq, p, ENQUEUE_NOCLOCK);
   4646	trace_sched_wakeup_new(p);
   4647	check_preempt_curr(rq, p, WF_FORK);
   4648#ifdef CONFIG_SMP
   4649	if (p->sched_class->task_woken) {
   4650		/*
   4651		 * Nothing relies on rq->lock after this, so it's fine to
   4652		 * drop it.
   4653		 */
   4654		rq_unpin_lock(rq, &rf);
   4655		p->sched_class->task_woken(rq, p);
   4656		rq_repin_lock(rq, &rf);
   4657	}
   4658#endif
   4659	task_rq_unlock(rq, p, &rf);
   4660}
   4661
   4662#ifdef CONFIG_PREEMPT_NOTIFIERS
   4663
   4664static DEFINE_STATIC_KEY_FALSE(preempt_notifier_key);
   4665
   4666void preempt_notifier_inc(void)
   4667{
   4668	static_branch_inc(&preempt_notifier_key);
   4669}
   4670EXPORT_SYMBOL_GPL(preempt_notifier_inc);
   4671
   4672void preempt_notifier_dec(void)
   4673{
   4674	static_branch_dec(&preempt_notifier_key);
   4675}
   4676EXPORT_SYMBOL_GPL(preempt_notifier_dec);
   4677
   4678/**
   4679 * preempt_notifier_register - tell me when current is being preempted & rescheduled
   4680 * @notifier: notifier struct to register
   4681 */
   4682void preempt_notifier_register(struct preempt_notifier *notifier)
   4683{
   4684	if (!static_branch_unlikely(&preempt_notifier_key))
   4685		WARN(1, "registering preempt_notifier while notifiers disabled\n");
   4686
   4687	hlist_add_head(&notifier->link, &current->preempt_notifiers);
   4688}
   4689EXPORT_SYMBOL_GPL(preempt_notifier_register);
   4690
   4691/**
   4692 * preempt_notifier_unregister - no longer interested in preemption notifications
   4693 * @notifier: notifier struct to unregister
   4694 *
   4695 * This is *not* safe to call from within a preemption notifier.
   4696 */
   4697void preempt_notifier_unregister(struct preempt_notifier *notifier)
   4698{
   4699	hlist_del(&notifier->link);
   4700}
   4701EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
   4702
   4703static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
   4704{
   4705	struct preempt_notifier *notifier;
   4706
   4707	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
   4708		notifier->ops->sched_in(notifier, raw_smp_processor_id());
   4709}
   4710
   4711static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
   4712{
   4713	if (static_branch_unlikely(&preempt_notifier_key))
   4714		__fire_sched_in_preempt_notifiers(curr);
   4715}
   4716
   4717static void
   4718__fire_sched_out_preempt_notifiers(struct task_struct *curr,
   4719				   struct task_struct *next)
   4720{
   4721	struct preempt_notifier *notifier;
   4722
   4723	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
   4724		notifier->ops->sched_out(notifier, next);
   4725}
   4726
   4727static __always_inline void
   4728fire_sched_out_preempt_notifiers(struct task_struct *curr,
   4729				 struct task_struct *next)
   4730{
   4731	if (static_branch_unlikely(&preempt_notifier_key))
   4732		__fire_sched_out_preempt_notifiers(curr, next);
   4733}
   4734
   4735#else /* !CONFIG_PREEMPT_NOTIFIERS */
   4736
   4737static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
   4738{
   4739}
   4740
   4741static inline void
   4742fire_sched_out_preempt_notifiers(struct task_struct *curr,
   4743				 struct task_struct *next)
   4744{
   4745}
   4746
   4747#endif /* CONFIG_PREEMPT_NOTIFIERS */
   4748
   4749static inline void prepare_task(struct task_struct *next)
   4750{
   4751#ifdef CONFIG_SMP
   4752	/*
   4753	 * Claim the task as running, we do this before switching to it
   4754	 * such that any running task will have this set.
   4755	 *
   4756	 * See the ttwu() WF_ON_CPU case and its ordering comment.
   4757	 */
   4758	WRITE_ONCE(next->on_cpu, 1);
   4759#endif
   4760}
   4761
   4762static inline void finish_task(struct task_struct *prev)
   4763{
   4764#ifdef CONFIG_SMP
   4765	/*
   4766	 * This must be the very last reference to @prev from this CPU. After
   4767	 * p->on_cpu is cleared, the task can be moved to a different CPU. We
   4768	 * must ensure this doesn't happen until the switch is completely
   4769	 * finished.
   4770	 *
   4771	 * In particular, the load of prev->state in finish_task_switch() must
   4772	 * happen before this.
   4773	 *
   4774	 * Pairs with the smp_cond_load_acquire() in try_to_wake_up().
   4775	 */
   4776	smp_store_release(&prev->on_cpu, 0);
   4777#endif
   4778}
   4779
   4780#ifdef CONFIG_SMP
   4781
   4782static void do_balance_callbacks(struct rq *rq, struct callback_head *head)
   4783{
   4784	void (*func)(struct rq *rq);
   4785	struct callback_head *next;
   4786
   4787	lockdep_assert_rq_held(rq);
   4788
   4789	while (head) {
   4790		func = (void (*)(struct rq *))head->func;
   4791		next = head->next;
   4792		head->next = NULL;
   4793		head = next;
   4794
   4795		func(rq);
   4796	}
   4797}
   4798
   4799static void balance_push(struct rq *rq);
   4800
   4801/*
   4802 * balance_push_callback is a right abuse of the callback interface and plays
   4803 * by significantly different rules.
   4804 *
   4805 * Where the normal balance_callback's purpose is to be ran in the same context
   4806 * that queued it (only later, when it's safe to drop rq->lock again),
   4807 * balance_push_callback is specifically targeted at __schedule().
   4808 *
   4809 * This abuse is tolerated because it places all the unlikely/odd cases behind
   4810 * a single test, namely: rq->balance_callback == NULL.
   4811 */
   4812struct callback_head balance_push_callback = {
   4813	.next = NULL,
   4814	.func = (void (*)(struct callback_head *))balance_push,
   4815};
   4816
   4817static inline struct callback_head *
   4818__splice_balance_callbacks(struct rq *rq, bool split)
   4819{
   4820	struct callback_head *head = rq->balance_callback;
   4821
   4822	if (likely(!head))
   4823		return NULL;
   4824
   4825	lockdep_assert_rq_held(rq);
   4826	/*
   4827	 * Must not take balance_push_callback off the list when
   4828	 * splice_balance_callbacks() and balance_callbacks() are not
   4829	 * in the same rq->lock section.
   4830	 *
   4831	 * In that case it would be possible for __schedule() to interleave
   4832	 * and observe the list empty.
   4833	 */
   4834	if (split && head == &balance_push_callback)
   4835		head = NULL;
   4836	else
   4837		rq->balance_callback = NULL;
   4838
   4839	return head;
   4840}
   4841
   4842static inline struct callback_head *splice_balance_callbacks(struct rq *rq)
   4843{
   4844	return __splice_balance_callbacks(rq, true);
   4845}
   4846
   4847static void __balance_callbacks(struct rq *rq)
   4848{
   4849	do_balance_callbacks(rq, __splice_balance_callbacks(rq, false));
   4850}
   4851
   4852static inline void balance_callbacks(struct rq *rq, struct callback_head *head)
   4853{
   4854	unsigned long flags;
   4855
   4856	if (unlikely(head)) {
   4857		raw_spin_rq_lock_irqsave(rq, flags);
   4858		do_balance_callbacks(rq, head);
   4859		raw_spin_rq_unlock_irqrestore(rq, flags);
   4860	}
   4861}
   4862
   4863#else
   4864
   4865static inline void __balance_callbacks(struct rq *rq)
   4866{
   4867}
   4868
   4869static inline struct callback_head *splice_balance_callbacks(struct rq *rq)
   4870{
   4871	return NULL;
   4872}
   4873
   4874static inline void balance_callbacks(struct rq *rq, struct callback_head *head)
   4875{
   4876}
   4877
   4878#endif
   4879
   4880static inline void
   4881prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf)
   4882{
   4883	/*
   4884	 * Since the runqueue lock will be released by the next
   4885	 * task (which is an invalid locking op but in the case
   4886	 * of the scheduler it's an obvious special-case), so we
   4887	 * do an early lockdep release here:
   4888	 */
   4889	rq_unpin_lock(rq, rf);
   4890	spin_release(&__rq_lockp(rq)->dep_map, _THIS_IP_);
   4891#ifdef CONFIG_DEBUG_SPINLOCK
   4892	/* this is a valid case when another task releases the spinlock */
   4893	rq_lockp(rq)->owner = next;
   4894#endif
   4895}
   4896
   4897static inline void finish_lock_switch(struct rq *rq)
   4898{
   4899	/*
   4900	 * If we are tracking spinlock dependencies then we have to
   4901	 * fix up the runqueue lock - which gets 'carried over' from
   4902	 * prev into current:
   4903	 */
   4904	spin_acquire(&__rq_lockp(rq)->dep_map, 0, 0, _THIS_IP_);
   4905	__balance_callbacks(rq);
   4906	raw_spin_rq_unlock_irq(rq);
   4907}
   4908
   4909/*
   4910 * NOP if the arch has not defined these:
   4911 */
   4912
   4913#ifndef prepare_arch_switch
   4914# define prepare_arch_switch(next)	do { } while (0)
   4915#endif
   4916
   4917#ifndef finish_arch_post_lock_switch
   4918# define finish_arch_post_lock_switch()	do { } while (0)
   4919#endif
   4920
   4921static inline void kmap_local_sched_out(void)
   4922{
   4923#ifdef CONFIG_KMAP_LOCAL
   4924	if (unlikely(current->kmap_ctrl.idx))
   4925		__kmap_local_sched_out();
   4926#endif
   4927}
   4928
   4929static inline void kmap_local_sched_in(void)
   4930{
   4931#ifdef CONFIG_KMAP_LOCAL
   4932	if (unlikely(current->kmap_ctrl.idx))
   4933		__kmap_local_sched_in();
   4934#endif
   4935}
   4936
   4937/**
   4938 * prepare_task_switch - prepare to switch tasks
   4939 * @rq: the runqueue preparing to switch
   4940 * @prev: the current task that is being switched out
   4941 * @next: the task we are going to switch to.
   4942 *
   4943 * This is called with the rq lock held and interrupts off. It must
   4944 * be paired with a subsequent finish_task_switch after the context
   4945 * switch.
   4946 *
   4947 * prepare_task_switch sets up locking and calls architecture specific
   4948 * hooks.
   4949 */
   4950static inline void
   4951prepare_task_switch(struct rq *rq, struct task_struct *prev,
   4952		    struct task_struct *next)
   4953{
   4954	kcov_prepare_switch(prev);
   4955	sched_info_switch(rq, prev, next);
   4956	perf_event_task_sched_out(prev, next);
   4957	rseq_preempt(prev);
   4958	fire_sched_out_preempt_notifiers(prev, next);
   4959	kmap_local_sched_out();
   4960	prepare_task(next);
   4961	prepare_arch_switch(next);
   4962}
   4963
   4964/**
   4965 * finish_task_switch - clean up after a task-switch
   4966 * @prev: the thread we just switched away from.
   4967 *
   4968 * finish_task_switch must be called after the context switch, paired
   4969 * with a prepare_task_switch call before the context switch.
   4970 * finish_task_switch will reconcile locking set up by prepare_task_switch,
   4971 * and do any other architecture-specific cleanup actions.
   4972 *
   4973 * Note that we may have delayed dropping an mm in context_switch(). If
   4974 * so, we finish that here outside of the runqueue lock. (Doing it
   4975 * with the lock held can cause deadlocks; see schedule() for
   4976 * details.)
   4977 *
   4978 * The context switch have flipped the stack from under us and restored the
   4979 * local variables which were saved when this task called schedule() in the
   4980 * past. prev == current is still correct but we need to recalculate this_rq
   4981 * because prev may have moved to another CPU.
   4982 */
   4983static struct rq *finish_task_switch(struct task_struct *prev)
   4984	__releases(rq->lock)
   4985{
   4986	struct rq *rq = this_rq();
   4987	struct mm_struct *mm = rq->prev_mm;
   4988	unsigned int prev_state;
   4989
   4990	/*
   4991	 * The previous task will have left us with a preempt_count of 2
   4992	 * because it left us after:
   4993	 *
   4994	 *	schedule()
   4995	 *	  preempt_disable();			// 1
   4996	 *	  __schedule()
   4997	 *	    raw_spin_lock_irq(&rq->lock)	// 2
   4998	 *
   4999	 * Also, see FORK_PREEMPT_COUNT.
   5000	 */
   5001	if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
   5002		      "corrupted preempt_count: %s/%d/0x%x\n",
   5003		      current->comm, current->pid, preempt_count()))
   5004		preempt_count_set(FORK_PREEMPT_COUNT);
   5005
   5006	rq->prev_mm = NULL;
   5007
   5008	/*
   5009	 * A task struct has one reference for the use as "current".
   5010	 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
   5011	 * schedule one last time. The schedule call will never return, and
   5012	 * the scheduled task must drop that reference.
   5013	 *
   5014	 * We must observe prev->state before clearing prev->on_cpu (in
   5015	 * finish_task), otherwise a concurrent wakeup can get prev
   5016	 * running on another CPU and we could rave with its RUNNING -> DEAD
   5017	 * transition, resulting in a double drop.
   5018	 */
   5019	prev_state = READ_ONCE(prev->__state);
   5020	vtime_task_switch(prev);
   5021	perf_event_task_sched_in(prev, current);
   5022	finish_task(prev);
   5023	tick_nohz_task_switch();
   5024	finish_lock_switch(rq);
   5025	finish_arch_post_lock_switch();
   5026	kcov_finish_switch(current);
   5027	/*
   5028	 * kmap_local_sched_out() is invoked with rq::lock held and
   5029	 * interrupts disabled. There is no requirement for that, but the
   5030	 * sched out code does not have an interrupt enabled section.
   5031	 * Restoring the maps on sched in does not require interrupts being
   5032	 * disabled either.
   5033	 */
   5034	kmap_local_sched_in();
   5035
   5036	fire_sched_in_preempt_notifiers(current);
   5037	/*
   5038	 * When switching through a kernel thread, the loop in
   5039	 * membarrier_{private,global}_expedited() may have observed that
   5040	 * kernel thread and not issued an IPI. It is therefore possible to
   5041	 * schedule between user->kernel->user threads without passing though
   5042	 * switch_mm(). Membarrier requires a barrier after storing to
   5043	 * rq->curr, before returning to userspace, so provide them here:
   5044	 *
   5045	 * - a full memory barrier for {PRIVATE,GLOBAL}_EXPEDITED, implicitly
   5046	 *   provided by mmdrop(),
   5047	 * - a sync_core for SYNC_CORE.
   5048	 */
   5049	if (mm) {
   5050		membarrier_mm_sync_core_before_usermode(mm);
   5051		mmdrop_sched(mm);
   5052	}
   5053	if (unlikely(prev_state == TASK_DEAD)) {
   5054		if (prev->sched_class->task_dead)
   5055			prev->sched_class->task_dead(prev);
   5056
   5057		/* Task is done with its stack. */
   5058		put_task_stack(prev);
   5059
   5060		put_task_struct_rcu_user(prev);
   5061	}
   5062
   5063	return rq;
   5064}
   5065
   5066/**
   5067 * schedule_tail - first thing a freshly forked thread must call.
   5068 * @prev: the thread we just switched away from.
   5069 */
   5070asmlinkage __visible void schedule_tail(struct task_struct *prev)
   5071	__releases(rq->lock)
   5072{
   5073	/*
   5074	 * New tasks start with FORK_PREEMPT_COUNT, see there and
   5075	 * finish_task_switch() for details.
   5076	 *
   5077	 * finish_task_switch() will drop rq->lock() and lower preempt_count
   5078	 * and the preempt_enable() will end up enabling preemption (on
   5079	 * PREEMPT_COUNT kernels).
   5080	 */
   5081
   5082	finish_task_switch(prev);
   5083	preempt_enable();
   5084
   5085	if (current->set_child_tid)
   5086		put_user(task_pid_vnr(current), current->set_child_tid);
   5087
   5088	calculate_sigpending();
   5089}
   5090
   5091/*
   5092 * context_switch - switch to the new MM and the new thread's register state.
   5093 */
   5094static __always_inline struct rq *
   5095context_switch(struct rq *rq, struct task_struct *prev,
   5096	       struct task_struct *next, struct rq_flags *rf)
   5097{
   5098	prepare_task_switch(rq, prev, next);
   5099
   5100	/*
   5101	 * For paravirt, this is coupled with an exit in switch_to to
   5102	 * combine the page table reload and the switch backend into
   5103	 * one hypercall.
   5104	 */
   5105	arch_start_context_switch(prev);
   5106
   5107	/*
   5108	 * kernel -> kernel   lazy + transfer active
   5109	 *   user -> kernel   lazy + mmgrab() active
   5110	 *
   5111	 * kernel ->   user   switch + mmdrop() active
   5112	 *   user ->   user   switch
   5113	 */
   5114	if (!next->mm) {                                // to kernel
   5115		enter_lazy_tlb(prev->active_mm, next);
   5116
   5117		next->active_mm = prev->active_mm;
   5118		if (prev->mm)                           // from user
   5119			mmgrab(prev->active_mm);
   5120		else
   5121			prev->active_mm = NULL;
   5122	} else {                                        // to user
   5123		membarrier_switch_mm(rq, prev->active_mm, next->mm);
   5124		/*
   5125		 * sys_membarrier() requires an smp_mb() between setting
   5126		 * rq->curr / membarrier_switch_mm() and returning to userspace.
   5127		 *
   5128		 * The below provides this either through switch_mm(), or in
   5129		 * case 'prev->active_mm == next->mm' through
   5130		 * finish_task_switch()'s mmdrop().
   5131		 */
   5132		switch_mm_irqs_off(prev->active_mm, next->mm, next);
   5133
   5134		if (!prev->mm) {                        // from kernel
   5135			/* will mmdrop() in finish_task_switch(). */
   5136			rq->prev_mm = prev->active_mm;
   5137			prev->active_mm = NULL;
   5138		}
   5139	}
   5140
   5141	rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
   5142
   5143	prepare_lock_switch(rq, next, rf);
   5144
   5145	/* Here we just switch the register state and the stack. */
   5146	switch_to(prev, next, prev);
   5147	barrier();
   5148
   5149	return finish_task_switch(prev);
   5150}
   5151
   5152/*
   5153 * nr_running and nr_context_switches:
   5154 *
   5155 * externally visible scheduler statistics: current number of runnable
   5156 * threads, total number of context switches performed since bootup.
   5157 */
   5158unsigned int nr_running(void)
   5159{
   5160	unsigned int i, sum = 0;
   5161
   5162	for_each_online_cpu(i)
   5163		sum += cpu_rq(i)->nr_running;
   5164
   5165	return sum;
   5166}
   5167
   5168/*
   5169 * Check if only the current task is running on the CPU.
   5170 *
   5171 * Caution: this function does not check that the caller has disabled
   5172 * preemption, thus the result might have a time-of-check-to-time-of-use
   5173 * race.  The caller is responsible to use it correctly, for example:
   5174 *
   5175 * - from a non-preemptible section (of course)
   5176 *
   5177 * - from a thread that is bound to a single CPU
   5178 *
   5179 * - in a loop with very short iterations (e.g. a polling loop)
   5180 */
   5181bool single_task_running(void)
   5182{
   5183	return raw_rq()->nr_running == 1;
   5184}
   5185EXPORT_SYMBOL(single_task_running);
   5186
   5187unsigned long long nr_context_switches(void)
   5188{
   5189	int i;
   5190	unsigned long long sum = 0;
   5191
   5192	for_each_possible_cpu(i)
   5193		sum += cpu_rq(i)->nr_switches;
   5194
   5195	return sum;
   5196}
   5197
   5198/*
   5199 * Consumers of these two interfaces, like for example the cpuidle menu
   5200 * governor, are using nonsensical data. Preferring shallow idle state selection
   5201 * for a CPU that has IO-wait which might not even end up running the task when
   5202 * it does become runnable.
   5203 */
   5204
   5205unsigned int nr_iowait_cpu(int cpu)
   5206{
   5207	return atomic_read(&cpu_rq(cpu)->nr_iowait);
   5208}
   5209
   5210/*
   5211 * IO-wait accounting, and how it's mostly bollocks (on SMP).
   5212 *
   5213 * The idea behind IO-wait account is to account the idle time that we could
   5214 * have spend running if it were not for IO. That is, if we were to improve the
   5215 * storage performance, we'd have a proportional reduction in IO-wait time.
   5216 *
   5217 * This all works nicely on UP, where, when a task blocks on IO, we account
   5218 * idle time as IO-wait, because if the storage were faster, it could've been
   5219 * running and we'd not be idle.
   5220 *
   5221 * This has been extended to SMP, by doing the same for each CPU. This however
   5222 * is broken.
   5223 *
   5224 * Imagine for instance the case where two tasks block on one CPU, only the one
   5225 * CPU will have IO-wait accounted, while the other has regular idle. Even
   5226 * though, if the storage were faster, both could've ran at the same time,
   5227 * utilising both CPUs.
   5228 *
   5229 * This means, that when looking globally, the current IO-wait accounting on
   5230 * SMP is a lower bound, by reason of under accounting.
   5231 *
   5232 * Worse, since the numbers are provided per CPU, they are sometimes
   5233 * interpreted per CPU, and that is nonsensical. A blocked task isn't strictly
   5234 * associated with any one particular CPU, it can wake to another CPU than it
   5235 * blocked on. This means the per CPU IO-wait number is meaningless.
   5236 *
   5237 * Task CPU affinities can make all that even more 'interesting'.
   5238 */
   5239
   5240unsigned int nr_iowait(void)
   5241{
   5242	unsigned int i, sum = 0;
   5243
   5244	for_each_possible_cpu(i)
   5245		sum += nr_iowait_cpu(i);
   5246
   5247	return sum;
   5248}
   5249
   5250#ifdef CONFIG_SMP
   5251
   5252/*
   5253 * sched_exec - execve() is a valuable balancing opportunity, because at
   5254 * this point the task has the smallest effective memory and cache footprint.
   5255 */
   5256void sched_exec(void)
   5257{
   5258	struct task_struct *p = current;
   5259	unsigned long flags;
   5260	int dest_cpu;
   5261
   5262	raw_spin_lock_irqsave(&p->pi_lock, flags);
   5263	dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), WF_EXEC);
   5264	if (dest_cpu == smp_processor_id())
   5265		goto unlock;
   5266
   5267	if (likely(cpu_active(dest_cpu))) {
   5268		struct migration_arg arg = { p, dest_cpu };
   5269
   5270		raw_spin_unlock_irqrestore(&p->pi_lock, flags);
   5271		stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
   5272		return;
   5273	}
   5274unlock:
   5275	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
   5276}
   5277
   5278#endif
   5279
   5280DEFINE_PER_CPU(struct kernel_stat, kstat);
   5281DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
   5282
   5283EXPORT_PER_CPU_SYMBOL(kstat);
   5284EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
   5285
   5286/*
   5287 * The function fair_sched_class.update_curr accesses the struct curr
   5288 * and its field curr->exec_start; when called from task_sched_runtime(),
   5289 * we observe a high rate of cache misses in practice.
   5290 * Prefetching this data results in improved performance.
   5291 */
   5292static inline void prefetch_curr_exec_start(struct task_struct *p)
   5293{
   5294#ifdef CONFIG_FAIR_GROUP_SCHED
   5295	struct sched_entity *curr = (&p->se)->cfs_rq->curr;
   5296#else
   5297	struct sched_entity *curr = (&task_rq(p)->cfs)->curr;
   5298#endif
   5299	prefetch(curr);
   5300	prefetch(&curr->exec_start);
   5301}
   5302
   5303/*
   5304 * Return accounted runtime for the task.
   5305 * In case the task is currently running, return the runtime plus current's
   5306 * pending runtime that have not been accounted yet.
   5307 */
   5308unsigned long long task_sched_runtime(struct task_struct *p)
   5309{
   5310	struct rq_flags rf;
   5311	struct rq *rq;
   5312	u64 ns;
   5313
   5314#if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
   5315	/*
   5316	 * 64-bit doesn't need locks to atomically read a 64-bit value.
   5317	 * So we have a optimization chance when the task's delta_exec is 0.
   5318	 * Reading ->on_cpu is racy, but this is ok.
   5319	 *
   5320	 * If we race with it leaving CPU, we'll take a lock. So we're correct.
   5321	 * If we race with it entering CPU, unaccounted time is 0. This is
   5322	 * indistinguishable from the read occurring a few cycles earlier.
   5323	 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
   5324	 * been accounted, so we're correct here as well.
   5325	 */
   5326	if (!p->on_cpu || !task_on_rq_queued(p))
   5327		return p->se.sum_exec_runtime;
   5328#endif
   5329
   5330	rq = task_rq_lock(p, &rf);
   5331	/*
   5332	 * Must be ->curr _and_ ->on_rq.  If dequeued, we would
   5333	 * project cycles that may never be accounted to this
   5334	 * thread, breaking clock_gettime().
   5335	 */
   5336	if (task_current(rq, p) && task_on_rq_queued(p)) {
   5337		prefetch_curr_exec_start(p);
   5338		update_rq_clock(rq);
   5339		p->sched_class->update_curr(rq);
   5340	}
   5341	ns = p->se.sum_exec_runtime;
   5342	task_rq_unlock(rq, p, &rf);
   5343
   5344	return ns;
   5345}
   5346
   5347#ifdef CONFIG_SCHED_DEBUG
   5348static u64 cpu_resched_latency(struct rq *rq)
   5349{
   5350	int latency_warn_ms = READ_ONCE(sysctl_resched_latency_warn_ms);
   5351	u64 resched_latency, now = rq_clock(rq);
   5352	static bool warned_once;
   5353
   5354	if (sysctl_resched_latency_warn_once && warned_once)
   5355		return 0;
   5356
   5357	if (!need_resched() || !latency_warn_ms)
   5358		return 0;
   5359
   5360	if (system_state == SYSTEM_BOOTING)
   5361		return 0;
   5362
   5363	if (!rq->last_seen_need_resched_ns) {
   5364		rq->last_seen_need_resched_ns = now;
   5365		rq->ticks_without_resched = 0;
   5366		return 0;
   5367	}
   5368
   5369	rq->ticks_without_resched++;
   5370	resched_latency = now - rq->last_seen_need_resched_ns;
   5371	if (resched_latency <= latency_warn_ms * NSEC_PER_MSEC)
   5372		return 0;
   5373
   5374	warned_once = true;
   5375
   5376	return resched_latency;
   5377}
   5378
   5379static int __init setup_resched_latency_warn_ms(char *str)
   5380{
   5381	long val;
   5382
   5383	if ((kstrtol(str, 0, &val))) {
   5384		pr_warn("Unable to set resched_latency_warn_ms\n");
   5385		return 1;
   5386	}
   5387
   5388	sysctl_resched_latency_warn_ms = val;
   5389	return 1;
   5390}
   5391__setup("resched_latency_warn_ms=", setup_resched_latency_warn_ms);
   5392#else
   5393static inline u64 cpu_resched_latency(struct rq *rq) { return 0; }
   5394#endif /* CONFIG_SCHED_DEBUG */
   5395
   5396/*
   5397 * This function gets called by the timer code, with HZ frequency.
   5398 * We call it with interrupts disabled.
   5399 */
   5400void scheduler_tick(void)
   5401{
   5402	int cpu = smp_processor_id();
   5403	struct rq *rq = cpu_rq(cpu);
   5404	struct task_struct *curr = rq->curr;
   5405	struct rq_flags rf;
   5406	unsigned long thermal_pressure;
   5407	u64 resched_latency;
   5408
   5409	arch_scale_freq_tick();
   5410	sched_clock_tick();
   5411
   5412	rq_lock(rq, &rf);
   5413
   5414	update_rq_clock(rq);
   5415	thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
   5416	update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure);
   5417	curr->sched_class->task_tick(rq, curr, 0);
   5418	if (sched_feat(LATENCY_WARN))
   5419		resched_latency = cpu_resched_latency(rq);
   5420	calc_global_load_tick(rq);
   5421	sched_core_tick(rq);
   5422
   5423	rq_unlock(rq, &rf);
   5424
   5425	if (sched_feat(LATENCY_WARN) && resched_latency)
   5426		resched_latency_warn(cpu, resched_latency);
   5427
   5428	perf_event_task_tick();
   5429
   5430#ifdef CONFIG_SMP
   5431	rq->idle_balance = idle_cpu(cpu);
   5432	trigger_load_balance(rq);
   5433#endif
   5434}
   5435
   5436#ifdef CONFIG_NO_HZ_FULL
   5437
   5438struct tick_work {
   5439	int			cpu;
   5440	atomic_t		state;
   5441	struct delayed_work	work;
   5442};
   5443/* Values for ->state, see diagram below. */
   5444#define TICK_SCHED_REMOTE_OFFLINE	0
   5445#define TICK_SCHED_REMOTE_OFFLINING	1
   5446#define TICK_SCHED_REMOTE_RUNNING	2
   5447
   5448/*
   5449 * State diagram for ->state:
   5450 *
   5451 *
   5452 *          TICK_SCHED_REMOTE_OFFLINE
   5453 *                    |   ^
   5454 *                    |   |
   5455 *                    |   | sched_tick_remote()
   5456 *                    |   |
   5457 *                    |   |
   5458 *                    +--TICK_SCHED_REMOTE_OFFLINING
   5459 *                    |   ^
   5460 *                    |   |
   5461 * sched_tick_start() |   | sched_tick_stop()
   5462 *                    |   |
   5463 *                    V   |
   5464 *          TICK_SCHED_REMOTE_RUNNING
   5465 *
   5466 *
   5467 * Other transitions get WARN_ON_ONCE(), except that sched_tick_remote()
   5468 * and sched_tick_start() are happy to leave the state in RUNNING.
   5469 */
   5470
   5471static struct tick_work __percpu *tick_work_cpu;
   5472
   5473static void sched_tick_remote(struct work_struct *work)
   5474{
   5475	struct delayed_work *dwork = to_delayed_work(work);
   5476	struct tick_work *twork = container_of(dwork, struct tick_work, work);
   5477	int cpu = twork->cpu;
   5478	struct rq *rq = cpu_rq(cpu);
   5479	struct task_struct *curr;
   5480	struct rq_flags rf;
   5481	u64 delta;
   5482	int os;
   5483
   5484	/*
   5485	 * Handle the tick only if it appears the remote CPU is running in full
   5486	 * dynticks mode. The check is racy by nature, but missing a tick or
   5487	 * having one too much is no big deal because the scheduler tick updates
   5488	 * statistics and checks timeslices in a time-independent way, regardless
   5489	 * of when exactly it is running.
   5490	 */
   5491	if (!tick_nohz_tick_stopped_cpu(cpu))
   5492		goto out_requeue;
   5493
   5494	rq_lock_irq(rq, &rf);
   5495	curr = rq->curr;
   5496	if (cpu_is_offline(cpu))
   5497		goto out_unlock;
   5498
   5499	update_rq_clock(rq);
   5500
   5501	if (!is_idle_task(curr)) {
   5502		/*
   5503		 * Make sure the next tick runs within a reasonable
   5504		 * amount of time.
   5505		 */
   5506		delta = rq_clock_task(rq) - curr->se.exec_start;
   5507		WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
   5508	}
   5509	curr->sched_class->task_tick(rq, curr, 0);
   5510
   5511	calc_load_nohz_remote(rq);
   5512out_unlock:
   5513	rq_unlock_irq(rq, &rf);
   5514out_requeue:
   5515
   5516	/*
   5517	 * Run the remote tick once per second (1Hz). This arbitrary
   5518	 * frequency is large enough to avoid overload but short enough
   5519	 * to keep scheduler internal stats reasonably up to date.  But
   5520	 * first update state to reflect hotplug activity if required.
   5521	 */
   5522	os = atomic_fetch_add_unless(&twork->state, -1, TICK_SCHED_REMOTE_RUNNING);
   5523	WARN_ON_ONCE(os == TICK_SCHED_REMOTE_OFFLINE);
   5524	if (os == TICK_SCHED_REMOTE_RUNNING)
   5525		queue_delayed_work(system_unbound_wq, dwork, HZ);
   5526}
   5527
   5528static void sched_tick_start(int cpu)
   5529{
   5530	int os;
   5531	struct tick_work *twork;
   5532
   5533	if (housekeeping_cpu(cpu, HK_TYPE_TICK))
   5534		return;
   5535
   5536	WARN_ON_ONCE(!tick_work_cpu);
   5537
   5538	twork = per_cpu_ptr(tick_work_cpu, cpu);
   5539	os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_RUNNING);
   5540	WARN_ON_ONCE(os == TICK_SCHED_REMOTE_RUNNING);
   5541	if (os == TICK_SCHED_REMOTE_OFFLINE) {
   5542		twork->cpu = cpu;
   5543		INIT_DELAYED_WORK(&twork->work, sched_tick_remote);
   5544		queue_delayed_work(system_unbound_wq, &twork->work, HZ);
   5545	}
   5546}
   5547
   5548#ifdef CONFIG_HOTPLUG_CPU
   5549static void sched_tick_stop(int cpu)
   5550{
   5551	struct tick_work *twork;
   5552	int os;
   5553
   5554	if (housekeeping_cpu(cpu, HK_TYPE_TICK))
   5555		return;
   5556
   5557	WARN_ON_ONCE(!tick_work_cpu);
   5558
   5559	twork = per_cpu_ptr(tick_work_cpu, cpu);
   5560	/* There cannot be competing actions, but don't rely on stop-machine. */
   5561	os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_OFFLINING);
   5562	WARN_ON_ONCE(os != TICK_SCHED_REMOTE_RUNNING);
   5563	/* Don't cancel, as this would mess up the state machine. */
   5564}
   5565#endif /* CONFIG_HOTPLUG_CPU */
   5566
   5567int __init sched_tick_offload_init(void)
   5568{
   5569	tick_work_cpu = alloc_percpu(struct tick_work);
   5570	BUG_ON(!tick_work_cpu);
   5571	return 0;
   5572}
   5573
   5574#else /* !CONFIG_NO_HZ_FULL */
   5575static inline void sched_tick_start(int cpu) { }
   5576static inline void sched_tick_stop(int cpu) { }
   5577#endif
   5578
   5579#if defined(CONFIG_PREEMPTION) && (defined(CONFIG_DEBUG_PREEMPT) || \
   5580				defined(CONFIG_TRACE_PREEMPT_TOGGLE))
   5581/*
   5582 * If the value passed in is equal to the current preempt count
   5583 * then we just disabled preemption. Start timing the latency.
   5584 */
   5585static inline void preempt_latency_start(int val)
   5586{
   5587	if (preempt_count() == val) {
   5588		unsigned long ip = get_lock_parent_ip();
   5589#ifdef CONFIG_DEBUG_PREEMPT
   5590		current->preempt_disable_ip = ip;
   5591#endif
   5592		trace_preempt_off(CALLER_ADDR0, ip);
   5593	}
   5594}
   5595
   5596void preempt_count_add(int val)
   5597{
   5598#ifdef CONFIG_DEBUG_PREEMPT
   5599	/*
   5600	 * Underflow?
   5601	 */
   5602	if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
   5603		return;
   5604#endif
   5605	__preempt_count_add(val);
   5606#ifdef CONFIG_DEBUG_PREEMPT
   5607	/*
   5608	 * Spinlock count overflowing soon?
   5609	 */
   5610	DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
   5611				PREEMPT_MASK - 10);
   5612#endif
   5613	preempt_latency_start(val);
   5614}
   5615EXPORT_SYMBOL(preempt_count_add);
   5616NOKPROBE_SYMBOL(preempt_count_add);
   5617
   5618/*
   5619 * If the value passed in equals to the current preempt count
   5620 * then we just enabled preemption. Stop timing the latency.
   5621 */
   5622static inline void preempt_latency_stop(int val)
   5623{
   5624	if (preempt_count() == val)
   5625		trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
   5626}
   5627
   5628void preempt_count_sub(int val)
   5629{
   5630#ifdef CONFIG_DEBUG_PREEMPT
   5631	/*
   5632	 * Underflow?
   5633	 */
   5634	if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
   5635		return;
   5636	/*
   5637	 * Is the spinlock portion underflowing?
   5638	 */
   5639	if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
   5640			!(preempt_count() & PREEMPT_MASK)))
   5641		return;
   5642#endif
   5643
   5644	preempt_latency_stop(val);
   5645	__preempt_count_sub(val);
   5646}
   5647EXPORT_SYMBOL(preempt_count_sub);
   5648NOKPROBE_SYMBOL(preempt_count_sub);
   5649
   5650#else
   5651static inline void preempt_latency_start(int val) { }
   5652static inline void preempt_latency_stop(int val) { }
   5653#endif
   5654
   5655static inline unsigned long get_preempt_disable_ip(struct task_struct *p)
   5656{
   5657#ifdef CONFIG_DEBUG_PREEMPT
   5658	return p->preempt_disable_ip;
   5659#else
   5660	return 0;
   5661#endif
   5662}
   5663
   5664/*
   5665 * Print scheduling while atomic bug:
   5666 */
   5667static noinline void __schedule_bug(struct task_struct *prev)
   5668{
   5669	/* Save this before calling printk(), since that will clobber it */
   5670	unsigned long preempt_disable_ip = get_preempt_disable_ip(current);
   5671
   5672	if (oops_in_progress)
   5673		return;
   5674
   5675	printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
   5676		prev->comm, prev->pid, preempt_count());
   5677
   5678	debug_show_held_locks(prev);
   5679	print_modules();
   5680	if (irqs_disabled())
   5681		print_irqtrace_events(prev);
   5682	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
   5683	    && in_atomic_preempt_off()) {
   5684		pr_err("Preemption disabled at:");
   5685		print_ip_sym(KERN_ERR, preempt_disable_ip);
   5686	}
   5687	if (panic_on_warn)
   5688		panic("scheduling while atomic\n");
   5689
   5690	dump_stack();
   5691	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
   5692}
   5693
   5694/*
   5695 * Various schedule()-time debugging checks and statistics:
   5696 */
   5697static inline void schedule_debug(struct task_struct *prev, bool preempt)
   5698{
   5699#ifdef CONFIG_SCHED_STACK_END_CHECK
   5700	if (task_stack_end_corrupted(prev))
   5701		panic("corrupted stack end detected inside scheduler\n");
   5702
   5703	if (task_scs_end_corrupted(prev))
   5704		panic("corrupted shadow stack detected inside scheduler\n");
   5705#endif
   5706
   5707#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
   5708	if (!preempt && READ_ONCE(prev->__state) && prev->non_block_count) {
   5709		printk(KERN_ERR "BUG: scheduling in a non-blocking section: %s/%d/%i\n",
   5710			prev->comm, prev->pid, prev->non_block_count);
   5711		dump_stack();
   5712		add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
   5713	}
   5714#endif
   5715
   5716	if (unlikely(in_atomic_preempt_off())) {
   5717		__schedule_bug(prev);
   5718		preempt_count_set(PREEMPT_DISABLED);
   5719	}
   5720	rcu_sleep_check();
   5721	SCHED_WARN_ON(ct_state() == CONTEXT_USER);
   5722
   5723	profile_hit(SCHED_PROFILING, __builtin_return_address(0));
   5724
   5725	schedstat_inc(this_rq()->sched_count);
   5726}
   5727
   5728static void put_prev_task_balance(struct rq *rq, struct task_struct *prev,
   5729				  struct rq_flags *rf)
   5730{
   5731#ifdef CONFIG_SMP
   5732	const struct sched_class *class;
   5733	/*
   5734	 * We must do the balancing pass before put_prev_task(), such
   5735	 * that when we release the rq->lock the task is in the same
   5736	 * state as before we took rq->lock.
   5737	 *
   5738	 * We can terminate the balance pass as soon as we know there is
   5739	 * a runnable task of @class priority or higher.
   5740	 */
   5741	for_class_range(class, prev->sched_class, &idle_sched_class) {
   5742		if (class->balance(rq, prev, rf))
   5743			break;
   5744	}
   5745#endif
   5746
   5747	put_prev_task(rq, prev);
   5748}
   5749
   5750/*
   5751 * Pick up the highest-prio task:
   5752 */
   5753static inline struct task_struct *
   5754__pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
   5755{
   5756	const struct sched_class *class;
   5757	struct task_struct *p;
   5758
   5759	/*
   5760	 * Optimization: we know that if all tasks are in the fair class we can
   5761	 * call that function directly, but only if the @prev task wasn't of a
   5762	 * higher scheduling class, because otherwise those lose the
   5763	 * opportunity to pull in more work from other CPUs.
   5764	 */
   5765	if (likely(!sched_class_above(prev->sched_class, &fair_sched_class) &&
   5766		   rq->nr_running == rq->cfs.h_nr_running)) {
   5767
   5768		p = pick_next_task_fair(rq, prev, rf);
   5769		if (unlikely(p == RETRY_TASK))
   5770			goto restart;
   5771
   5772		/* Assume the next prioritized class is idle_sched_class */
   5773		if (!p) {
   5774			put_prev_task(rq, prev);
   5775			p = pick_next_task_idle(rq);
   5776		}
   5777
   5778		return p;
   5779	}
   5780
   5781restart:
   5782	put_prev_task_balance(rq, prev, rf);
   5783
   5784	for_each_class(class) {
   5785		p = class->pick_next_task(rq);
   5786		if (p)
   5787			return p;
   5788	}
   5789
   5790	BUG(); /* The idle class should always have a runnable task. */
   5791}
   5792
   5793#ifdef CONFIG_SCHED_CORE
   5794static inline bool is_task_rq_idle(struct task_struct *t)
   5795{
   5796	return (task_rq(t)->idle == t);
   5797}
   5798
   5799static inline bool cookie_equals(struct task_struct *a, unsigned long cookie)
   5800{
   5801	return is_task_rq_idle(a) || (a->core_cookie == cookie);
   5802}
   5803
   5804static inline bool cookie_match(struct task_struct *a, struct task_struct *b)
   5805{
   5806	if (is_task_rq_idle(a) || is_task_rq_idle(b))
   5807		return true;
   5808
   5809	return a->core_cookie == b->core_cookie;
   5810}
   5811
   5812static inline struct task_struct *pick_task(struct rq *rq)
   5813{
   5814	const struct sched_class *class;
   5815	struct task_struct *p;
   5816
   5817	for_each_class(class) {
   5818		p = class->pick_task(rq);
   5819		if (p)
   5820			return p;
   5821	}
   5822
   5823	BUG(); /* The idle class should always have a runnable task. */
   5824}
   5825
   5826extern void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi);
   5827
   5828static void queue_core_balance(struct rq *rq);
   5829
   5830static struct task_struct *
   5831pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
   5832{
   5833	struct task_struct *next, *p, *max = NULL;
   5834	const struct cpumask *smt_mask;
   5835	bool fi_before = false;
   5836	bool core_clock_updated = (rq == rq->core);
   5837	unsigned long cookie;
   5838	int i, cpu, occ = 0;
   5839	struct rq *rq_i;
   5840	bool need_sync;
   5841
   5842	if (!sched_core_enabled(rq))
   5843		return __pick_next_task(rq, prev, rf);
   5844
   5845	cpu = cpu_of(rq);
   5846
   5847	/* Stopper task is switching into idle, no need core-wide selection. */
   5848	if (cpu_is_offline(cpu)) {
   5849		/*
   5850		 * Reset core_pick so that we don't enter the fastpath when
   5851		 * coming online. core_pick would already be migrated to
   5852		 * another cpu during offline.
   5853		 */
   5854		rq->core_pick = NULL;
   5855		return __pick_next_task(rq, prev, rf);
   5856	}
   5857
   5858	/*
   5859	 * If there were no {en,de}queues since we picked (IOW, the task
   5860	 * pointers are all still valid), and we haven't scheduled the last
   5861	 * pick yet, do so now.
   5862	 *
   5863	 * rq->core_pick can be NULL if no selection was made for a CPU because
   5864	 * it was either offline or went offline during a sibling's core-wide
   5865	 * selection. In this case, do a core-wide selection.
   5866	 */
   5867	if (rq->core->core_pick_seq == rq->core->core_task_seq &&
   5868	    rq->core->core_pick_seq != rq->core_sched_seq &&
   5869	    rq->core_pick) {
   5870		WRITE_ONCE(rq->core_sched_seq, rq->core->core_pick_seq);
   5871
   5872		next = rq->core_pick;
   5873		if (next != prev) {
   5874			put_prev_task(rq, prev);
   5875			set_next_task(rq, next);
   5876		}
   5877
   5878		rq->core_pick = NULL;
   5879		goto out;
   5880	}
   5881
   5882	put_prev_task_balance(rq, prev, rf);
   5883
   5884	smt_mask = cpu_smt_mask(cpu);
   5885	need_sync = !!rq->core->core_cookie;
   5886
   5887	/* reset state */
   5888	rq->core->core_cookie = 0UL;
   5889	if (rq->core->core_forceidle_count) {
   5890		if (!core_clock_updated) {
   5891			update_rq_clock(rq->core);
   5892			core_clock_updated = true;
   5893		}
   5894		sched_core_account_forceidle(rq);
   5895		/* reset after accounting force idle */
   5896		rq->core->core_forceidle_start = 0;
   5897		rq->core->core_forceidle_count = 0;
   5898		rq->core->core_forceidle_occupation = 0;
   5899		need_sync = true;
   5900		fi_before = true;
   5901	}
   5902
   5903	/*
   5904	 * core->core_task_seq, core->core_pick_seq, rq->core_sched_seq
   5905	 *
   5906	 * @task_seq guards the task state ({en,de}queues)
   5907	 * @pick_seq is the @task_seq we did a selection on
   5908	 * @sched_seq is the @pick_seq we scheduled
   5909	 *
   5910	 * However, preemptions can cause multiple picks on the same task set.
   5911	 * 'Fix' this by also increasing @task_seq for every pick.
   5912	 */
   5913	rq->core->core_task_seq++;
   5914
   5915	/*
   5916	 * Optimize for common case where this CPU has no cookies
   5917	 * and there are no cookied tasks running on siblings.
   5918	 */
   5919	if (!need_sync) {
   5920		next = pick_task(rq);
   5921		if (!next->core_cookie) {
   5922			rq->core_pick = NULL;
   5923			/*
   5924			 * For robustness, update the min_vruntime_fi for
   5925			 * unconstrained picks as well.
   5926			 */
   5927			WARN_ON_ONCE(fi_before);
   5928			task_vruntime_update(rq, next, false);
   5929			goto out_set_next;
   5930		}
   5931	}
   5932
   5933	/*
   5934	 * For each thread: do the regular task pick and find the max prio task
   5935	 * amongst them.
   5936	 *
   5937	 * Tie-break prio towards the current CPU
   5938	 */
   5939	for_each_cpu_wrap(i, smt_mask, cpu) {
   5940		rq_i = cpu_rq(i);
   5941
   5942		/*
   5943		 * Current cpu always has its clock updated on entrance to
   5944		 * pick_next_task(). If the current cpu is not the core,
   5945		 * the core may also have been updated above.
   5946		 */
   5947		if (i != cpu && (rq_i != rq->core || !core_clock_updated))
   5948			update_rq_clock(rq_i);
   5949
   5950		p = rq_i->core_pick = pick_task(rq_i);
   5951		if (!max || prio_less(max, p, fi_before))
   5952			max = p;
   5953	}
   5954
   5955	cookie = rq->core->core_cookie = max->core_cookie;
   5956
   5957	/*
   5958	 * For each thread: try and find a runnable task that matches @max or
   5959	 * force idle.
   5960	 */
   5961	for_each_cpu(i, smt_mask) {
   5962		rq_i = cpu_rq(i);
   5963		p = rq_i->core_pick;
   5964
   5965		if (!cookie_equals(p, cookie)) {
   5966			p = NULL;
   5967			if (cookie)
   5968				p = sched_core_find(rq_i, cookie);
   5969			if (!p)
   5970				p = idle_sched_class.pick_task(rq_i);
   5971		}
   5972
   5973		rq_i->core_pick = p;
   5974
   5975		if (p == rq_i->idle) {
   5976			if (rq_i->nr_running) {
   5977				rq->core->core_forceidle_count++;
   5978				if (!fi_before)
   5979					rq->core->core_forceidle_seq++;
   5980			}
   5981		} else {
   5982			occ++;
   5983		}
   5984	}
   5985
   5986	if (schedstat_enabled() && rq->core->core_forceidle_count) {
   5987		rq->core->core_forceidle_start = rq_clock(rq->core);
   5988		rq->core->core_forceidle_occupation = occ;
   5989	}
   5990
   5991	rq->core->core_pick_seq = rq->core->core_task_seq;
   5992	next = rq->core_pick;
   5993	rq->core_sched_seq = rq->core->core_pick_seq;
   5994
   5995	/* Something should have been selected for current CPU */
   5996	WARN_ON_ONCE(!next);
   5997
   5998	/*
   5999	 * Reschedule siblings
   6000	 *
   6001	 * NOTE: L1TF -- at this point we're no longer running the old task and
   6002	 * sending an IPI (below) ensures the sibling will no longer be running
   6003	 * their task. This ensures there is no inter-sibling overlap between
   6004	 * non-matching user state.
   6005	 */
   6006	for_each_cpu(i, smt_mask) {
   6007		rq_i = cpu_rq(i);
   6008
   6009		/*
   6010		 * An online sibling might have gone offline before a task
   6011		 * could be picked for it, or it might be offline but later
   6012		 * happen to come online, but its too late and nothing was
   6013		 * picked for it.  That's Ok - it will pick tasks for itself,
   6014		 * so ignore it.
   6015		 */
   6016		if (!rq_i->core_pick)
   6017			continue;
   6018
   6019		/*
   6020		 * Update for new !FI->FI transitions, or if continuing to be in !FI:
   6021		 * fi_before     fi      update?
   6022		 *  0            0       1
   6023		 *  0            1       1
   6024		 *  1            0       1
   6025		 *  1            1       0
   6026		 */
   6027		if (!(fi_before && rq->core->core_forceidle_count))
   6028			task_vruntime_update(rq_i, rq_i->core_pick, !!rq->core->core_forceidle_count);
   6029
   6030		rq_i->core_pick->core_occupation = occ;
   6031
   6032		if (i == cpu) {
   6033			rq_i->core_pick = NULL;
   6034			continue;
   6035		}
   6036
   6037		/* Did we break L1TF mitigation requirements? */
   6038		WARN_ON_ONCE(!cookie_match(next, rq_i->core_pick));
   6039
   6040		if (rq_i->curr == rq_i->core_pick) {
   6041			rq_i->core_pick = NULL;
   6042			continue;
   6043		}
   6044
   6045		resched_curr(rq_i);
   6046	}
   6047
   6048out_set_next:
   6049	set_next_task(rq, next);
   6050out:
   6051	if (rq->core->core_forceidle_count && next == rq->idle)
   6052		queue_core_balance(rq);
   6053
   6054	return next;
   6055}
   6056
   6057static bool try_steal_cookie(int this, int that)
   6058{
   6059	struct rq *dst = cpu_rq(this), *src = cpu_rq(that);
   6060	struct task_struct *p;
   6061	unsigned long cookie;
   6062	bool success = false;
   6063
   6064	local_irq_disable();
   6065	double_rq_lock(dst, src);
   6066
   6067	cookie = dst->core->core_cookie;
   6068	if (!cookie)
   6069		goto unlock;
   6070
   6071	if (dst->curr != dst->idle)
   6072		goto unlock;
   6073
   6074	p = sched_core_find(src, cookie);
   6075	if (p == src->idle)
   6076		goto unlock;
   6077
   6078	do {
   6079		if (p == src->core_pick || p == src->curr)
   6080			goto next;
   6081
   6082		if (!is_cpu_allowed(p, this))
   6083			goto next;
   6084
   6085		if (p->core_occupation > dst->idle->core_occupation)
   6086			goto next;
   6087
   6088		deactivate_task(src, p, 0);
   6089		set_task_cpu(p, this);
   6090		activate_task(dst, p, 0);
   6091
   6092		resched_curr(dst);
   6093
   6094		success = true;
   6095		break;
   6096
   6097next:
   6098		p = sched_core_next(p, cookie);
   6099	} while (p);
   6100
   6101unlock:
   6102	double_rq_unlock(dst, src);
   6103	local_irq_enable();
   6104
   6105	return success;
   6106}
   6107
   6108static bool steal_cookie_task(int cpu, struct sched_domain *sd)
   6109{
   6110	int i;
   6111
   6112	for_each_cpu_wrap(i, sched_domain_span(sd), cpu) {
   6113		if (i == cpu)
   6114			continue;
   6115
   6116		if (need_resched())
   6117			break;
   6118
   6119		if (try_steal_cookie(cpu, i))
   6120			return true;
   6121	}
   6122
   6123	return false;
   6124}
   6125
   6126static void sched_core_balance(struct rq *rq)
   6127{
   6128	struct sched_domain *sd;
   6129	int cpu = cpu_of(rq);
   6130
   6131	preempt_disable();
   6132	rcu_read_lock();
   6133	raw_spin_rq_unlock_irq(rq);
   6134	for_each_domain(cpu, sd) {
   6135		if (need_resched())
   6136			break;
   6137
   6138		if (steal_cookie_task(cpu, sd))
   6139			break;
   6140	}
   6141	raw_spin_rq_lock_irq(rq);
   6142	rcu_read_unlock();
   6143	preempt_enable();
   6144}
   6145
   6146static DEFINE_PER_CPU(struct callback_head, core_balance_head);
   6147
   6148static void queue_core_balance(struct rq *rq)
   6149{
   6150	if (!sched_core_enabled(rq))
   6151		return;
   6152
   6153	if (!rq->core->core_cookie)
   6154		return;
   6155
   6156	if (!rq->nr_running) /* not forced idle */
   6157		return;
   6158
   6159	queue_balance_callback(rq, &per_cpu(core_balance_head, rq->cpu), sched_core_balance);
   6160}
   6161
   6162static void sched_core_cpu_starting(unsigned int cpu)
   6163{
   6164	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
   6165	struct rq *rq = cpu_rq(cpu), *core_rq = NULL;
   6166	unsigned long flags;
   6167	int t;
   6168
   6169	sched_core_lock(cpu, &flags);
   6170
   6171	WARN_ON_ONCE(rq->core != rq);
   6172
   6173	/* if we're the first, we'll be our own leader */
   6174	if (cpumask_weight(smt_mask) == 1)
   6175		goto unlock;
   6176
   6177	/* find the leader */
   6178	for_each_cpu(t, smt_mask) {
   6179		if (t == cpu)
   6180			continue;
   6181		rq = cpu_rq(t);
   6182		if (rq->core == rq) {
   6183			core_rq = rq;
   6184			break;
   6185		}
   6186	}
   6187
   6188	if (WARN_ON_ONCE(!core_rq)) /* whoopsie */
   6189		goto unlock;
   6190
   6191	/* install and validate core_rq */
   6192	for_each_cpu(t, smt_mask) {
   6193		rq = cpu_rq(t);
   6194
   6195		if (t == cpu)
   6196			rq->core = core_rq;
   6197
   6198		WARN_ON_ONCE(rq->core != core_rq);
   6199	}
   6200
   6201unlock:
   6202	sched_core_unlock(cpu, &flags);
   6203}
   6204
   6205static void sched_core_cpu_deactivate(unsigned int cpu)
   6206{
   6207	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
   6208	struct rq *rq = cpu_rq(cpu), *core_rq = NULL;
   6209	unsigned long flags;
   6210	int t;
   6211
   6212	sched_core_lock(cpu, &flags);
   6213
   6214	/* if we're the last man standing, nothing to do */
   6215	if (cpumask_weight(smt_mask) == 1) {
   6216		WARN_ON_ONCE(rq->core != rq);
   6217		goto unlock;
   6218	}
   6219
   6220	/* if we're not the leader, nothing to do */
   6221	if (rq->core != rq)
   6222		goto unlock;
   6223
   6224	/* find a new leader */
   6225	for_each_cpu(t, smt_mask) {
   6226		if (t == cpu)
   6227			continue;
   6228		core_rq = cpu_rq(t);
   6229		break;
   6230	}
   6231
   6232	if (WARN_ON_ONCE(!core_rq)) /* impossible */
   6233		goto unlock;
   6234
   6235	/* copy the shared state to the new leader */
   6236	core_rq->core_task_seq             = rq->core_task_seq;
   6237	core_rq->core_pick_seq             = rq->core_pick_seq;
   6238	core_rq->core_cookie               = rq->core_cookie;
   6239	core_rq->core_forceidle_count      = rq->core_forceidle_count;
   6240	core_rq->core_forceidle_seq        = rq->core_forceidle_seq;
   6241	core_rq->core_forceidle_occupation = rq->core_forceidle_occupation;
   6242
   6243	/*
   6244	 * Accounting edge for forced idle is handled in pick_next_task().
   6245	 * Don't need another one here, since the hotplug thread shouldn't
   6246	 * have a cookie.
   6247	 */
   6248	core_rq->core_forceidle_start = 0;
   6249
   6250	/* install new leader */
   6251	for_each_cpu(t, smt_mask) {
   6252		rq = cpu_rq(t);
   6253		rq->core = core_rq;
   6254	}
   6255
   6256unlock:
   6257	sched_core_unlock(cpu, &flags);
   6258}
   6259
   6260static inline void sched_core_cpu_dying(unsigned int cpu)
   6261{
   6262	struct rq *rq = cpu_rq(cpu);
   6263
   6264	if (rq->core != rq)
   6265		rq->core = rq;
   6266}
   6267
   6268#else /* !CONFIG_SCHED_CORE */
   6269
   6270static inline void sched_core_cpu_starting(unsigned int cpu) {}
   6271static inline void sched_core_cpu_deactivate(unsigned int cpu) {}
   6272static inline void sched_core_cpu_dying(unsigned int cpu) {}
   6273
   6274static struct task_struct *
   6275pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
   6276{
   6277	return __pick_next_task(rq, prev, rf);
   6278}
   6279
   6280#endif /* CONFIG_SCHED_CORE */
   6281
   6282/*
   6283 * Constants for the sched_mode argument of __schedule().
   6284 *
   6285 * The mode argument allows RT enabled kernels to differentiate a
   6286 * preemption from blocking on an 'sleeping' spin/rwlock. Note that
   6287 * SM_MASK_PREEMPT for !RT has all bits set, which allows the compiler to
   6288 * optimize the AND operation out and just check for zero.
   6289 */
   6290#define SM_NONE			0x0
   6291#define SM_PREEMPT		0x1
   6292#define SM_RTLOCK_WAIT		0x2
   6293
   6294#ifndef CONFIG_PREEMPT_RT
   6295# define SM_MASK_PREEMPT	(~0U)
   6296#else
   6297# define SM_MASK_PREEMPT	SM_PREEMPT
   6298#endif
   6299
   6300/*
   6301 * __schedule() is the main scheduler function.
   6302 *
   6303 * The main means of driving the scheduler and thus entering this function are:
   6304 *
   6305 *   1. Explicit blocking: mutex, semaphore, waitqueue, etc.
   6306 *
   6307 *   2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
   6308 *      paths. For example, see arch/x86/entry_64.S.
   6309 *
   6310 *      To drive preemption between tasks, the scheduler sets the flag in timer
   6311 *      interrupt handler scheduler_tick().
   6312 *
   6313 *   3. Wakeups don't really cause entry into schedule(). They add a
   6314 *      task to the run-queue and that's it.
   6315 *
   6316 *      Now, if the new task added to the run-queue preempts the current
   6317 *      task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
   6318 *      called on the nearest possible occasion:
   6319 *
   6320 *       - If the kernel is preemptible (CONFIG_PREEMPTION=y):
   6321 *
   6322 *         - in syscall or exception context, at the next outmost
   6323 *           preempt_enable(). (this might be as soon as the wake_up()'s
   6324 *           spin_unlock()!)
   6325 *
   6326 *         - in IRQ context, return from interrupt-handler to
   6327 *           preemptible context
   6328 *
   6329 *       - If the kernel is not preemptible (CONFIG_PREEMPTION is not set)
   6330 *         then at the next:
   6331 *
   6332 *          - cond_resched() call
   6333 *          - explicit schedule() call
   6334 *          - return from syscall or exception to user-space
   6335 *          - return from interrupt-handler to user-space
   6336 *
   6337 * WARNING: must be called with preemption disabled!
   6338 */
   6339static void __sched notrace __schedule(unsigned int sched_mode)
   6340{
   6341	struct task_struct *prev, *next;
   6342	unsigned long *switch_count;
   6343	unsigned long prev_state;
   6344	struct rq_flags rf;
   6345	struct rq *rq;
   6346	int cpu;
   6347
   6348	cpu = smp_processor_id();
   6349	rq = cpu_rq(cpu);
   6350	prev = rq->curr;
   6351
   6352	schedule_debug(prev, !!sched_mode);
   6353
   6354	if (sched_feat(HRTICK) || sched_feat(HRTICK_DL))
   6355		hrtick_clear(rq);
   6356
   6357	local_irq_disable();
   6358	rcu_note_context_switch(!!sched_mode);
   6359
   6360	/*
   6361	 * Make sure that signal_pending_state()->signal_pending() below
   6362	 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
   6363	 * done by the caller to avoid the race with signal_wake_up():
   6364	 *
   6365	 * __set_current_state(@state)		signal_wake_up()
   6366	 * schedule()				  set_tsk_thread_flag(p, TIF_SIGPENDING)
   6367	 *					  wake_up_state(p, state)
   6368	 *   LOCK rq->lock			    LOCK p->pi_state
   6369	 *   smp_mb__after_spinlock()		    smp_mb__after_spinlock()
   6370	 *     if (signal_pending_state())	    if (p->state & @state)
   6371	 *
   6372	 * Also, the membarrier system call requires a full memory barrier
   6373	 * after coming from user-space, before storing to rq->curr.
   6374	 */
   6375	rq_lock(rq, &rf);
   6376	smp_mb__after_spinlock();
   6377
   6378	/* Promote REQ to ACT */
   6379	rq->clock_update_flags <<= 1;
   6380	update_rq_clock(rq);
   6381
   6382	switch_count = &prev->nivcsw;
   6383
   6384	/*
   6385	 * We must load prev->state once (task_struct::state is volatile), such
   6386	 * that we form a control dependency vs deactivate_task() below.
   6387	 */
   6388	prev_state = READ_ONCE(prev->__state);
   6389	if (!(sched_mode & SM_MASK_PREEMPT) && prev_state) {
   6390		if (signal_pending_state(prev_state, prev)) {
   6391			WRITE_ONCE(prev->__state, TASK_RUNNING);
   6392		} else {
   6393			prev->sched_contributes_to_load =
   6394				(prev_state & TASK_UNINTERRUPTIBLE) &&
   6395				!(prev_state & TASK_NOLOAD) &&
   6396				!(prev->flags & PF_FROZEN);
   6397
   6398			if (prev->sched_contributes_to_load)
   6399				rq->nr_uninterruptible++;
   6400
   6401			/*
   6402			 * __schedule()			ttwu()
   6403			 *   prev_state = prev->state;    if (p->on_rq && ...)
   6404			 *   if (prev_state)		    goto out;
   6405			 *     p->on_rq = 0;		  smp_acquire__after_ctrl_dep();
   6406			 *				  p->state = TASK_WAKING
   6407			 *
   6408			 * Where __schedule() and ttwu() have matching control dependencies.
   6409			 *
   6410			 * After this, schedule() must not care about p->state any more.
   6411			 */
   6412			deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK);
   6413
   6414			if (prev->in_iowait) {
   6415				atomic_inc(&rq->nr_iowait);
   6416				delayacct_blkio_start();
   6417			}
   6418		}
   6419		switch_count = &prev->nvcsw;
   6420	}
   6421
   6422	next = pick_next_task(rq, prev, &rf);
   6423	clear_tsk_need_resched(prev);
   6424	clear_preempt_need_resched();
   6425#ifdef CONFIG_SCHED_DEBUG
   6426	rq->last_seen_need_resched_ns = 0;
   6427#endif
   6428
   6429	if (likely(prev != next)) {
   6430		rq->nr_switches++;
   6431		/*
   6432		 * RCU users of rcu_dereference(rq->curr) may not see
   6433		 * changes to task_struct made by pick_next_task().
   6434		 */
   6435		RCU_INIT_POINTER(rq->curr, next);
   6436		/*
   6437		 * The membarrier system call requires each architecture
   6438		 * to have a full memory barrier after updating
   6439		 * rq->curr, before returning to user-space.
   6440		 *
   6441		 * Here are the schemes providing that barrier on the
   6442		 * various architectures:
   6443		 * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC.
   6444		 *   switch_mm() rely on membarrier_arch_switch_mm() on PowerPC.
   6445		 * - finish_lock_switch() for weakly-ordered
   6446		 *   architectures where spin_unlock is a full barrier,
   6447		 * - switch_to() for arm64 (weakly-ordered, spin_unlock
   6448		 *   is a RELEASE barrier),
   6449		 */
   6450		++*switch_count;
   6451
   6452		migrate_disable_switch(rq, prev);
   6453		psi_sched_switch(prev, next, !task_on_rq_queued(prev));
   6454
   6455		trace_sched_switch(sched_mode & SM_MASK_PREEMPT, prev, next, prev_state);
   6456
   6457		/* Also unlocks the rq: */
   6458		rq = context_switch(rq, prev, next, &rf);
   6459	} else {
   6460		rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
   6461
   6462		rq_unpin_lock(rq, &rf);
   6463		__balance_callbacks(rq);
   6464		raw_spin_rq_unlock_irq(rq);
   6465	}
   6466}
   6467
   6468void __noreturn do_task_dead(void)
   6469{
   6470	/* Causes final put_task_struct in finish_task_switch(): */
   6471	set_special_state(TASK_DEAD);
   6472
   6473	/* Tell freezer to ignore us: */
   6474	current->flags |= PF_NOFREEZE;
   6475
   6476	__schedule(SM_NONE);
   6477	BUG();
   6478
   6479	/* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */
   6480	for (;;)
   6481		cpu_relax();
   6482}
   6483
   6484static inline void sched_submit_work(struct task_struct *tsk)
   6485{
   6486	unsigned int task_flags;
   6487
   6488	if (task_is_running(tsk))
   6489		return;
   6490
   6491	task_flags = tsk->flags;
   6492	/*
   6493	 * If a worker goes to sleep, notify and ask workqueue whether it
   6494	 * wants to wake up a task to maintain concurrency.
   6495	 */
   6496	if (task_flags & (PF_WQ_WORKER | PF_IO_WORKER)) {
   6497		if (task_flags & PF_WQ_WORKER)
   6498			wq_worker_sleeping(tsk);
   6499		else
   6500			io_wq_worker_sleeping(tsk);
   6501	}
   6502
   6503	if (tsk_is_pi_blocked(tsk))
   6504		return;
   6505
   6506	/*
   6507	 * If we are going to sleep and we have plugged IO queued,
   6508	 * make sure to submit it to avoid deadlocks.
   6509	 */
   6510	blk_flush_plug(tsk->plug, true);
   6511}
   6512
   6513static void sched_update_worker(struct task_struct *tsk)
   6514{
   6515	if (tsk->flags & (PF_WQ_WORKER | PF_IO_WORKER)) {
   6516		if (tsk->flags & PF_WQ_WORKER)
   6517			wq_worker_running(tsk);
   6518		else
   6519			io_wq_worker_running(tsk);
   6520	}
   6521}
   6522
   6523asmlinkage __visible void __sched schedule(void)
   6524{
   6525	struct task_struct *tsk = current;
   6526
   6527	sched_submit_work(tsk);
   6528	do {
   6529		preempt_disable();
   6530		__schedule(SM_NONE);
   6531		sched_preempt_enable_no_resched();
   6532	} while (need_resched());
   6533	sched_update_worker(tsk);
   6534}
   6535EXPORT_SYMBOL(schedule);
   6536
   6537/*
   6538 * synchronize_rcu_tasks() makes sure that no task is stuck in preempted
   6539 * state (have scheduled out non-voluntarily) by making sure that all
   6540 * tasks have either left the run queue or have gone into user space.
   6541 * As idle tasks do not do either, they must not ever be preempted
   6542 * (schedule out non-voluntarily).
   6543 *
   6544 * schedule_idle() is similar to schedule_preempt_disable() except that it
   6545 * never enables preemption because it does not call sched_submit_work().
   6546 */
   6547void __sched schedule_idle(void)
   6548{
   6549	/*
   6550	 * As this skips calling sched_submit_work(), which the idle task does
   6551	 * regardless because that function is a nop when the task is in a
   6552	 * TASK_RUNNING state, make sure this isn't used someplace that the
   6553	 * current task can be in any other state. Note, idle is always in the
   6554	 * TASK_RUNNING state.
   6555	 */
   6556	WARN_ON_ONCE(current->__state);
   6557	do {
   6558		__schedule(SM_NONE);
   6559	} while (need_resched());
   6560}
   6561
   6562#if defined(CONFIG_CONTEXT_TRACKING) && !defined(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK)
   6563asmlinkage __visible void __sched schedule_user(void)
   6564{
   6565	/*
   6566	 * If we come here after a random call to set_need_resched(),
   6567	 * or we have been woken up remotely but the IPI has not yet arrived,
   6568	 * we haven't yet exited the RCU idle mode. Do it here manually until
   6569	 * we find a better solution.
   6570	 *
   6571	 * NB: There are buggy callers of this function.  Ideally we
   6572	 * should warn if prev_state != CONTEXT_USER, but that will trigger
   6573	 * too frequently to make sense yet.
   6574	 */
   6575	enum ctx_state prev_state = exception_enter();
   6576	schedule();
   6577	exception_exit(prev_state);
   6578}
   6579#endif
   6580
   6581/**
   6582 * schedule_preempt_disabled - called with preemption disabled
   6583 *
   6584 * Returns with preemption disabled. Note: preempt_count must be 1
   6585 */
   6586void __sched schedule_preempt_disabled(void)
   6587{
   6588	sched_preempt_enable_no_resched();
   6589	schedule();
   6590	preempt_disable();
   6591}
   6592
   6593#ifdef CONFIG_PREEMPT_RT
   6594void __sched notrace schedule_rtlock(void)
   6595{
   6596	do {
   6597		preempt_disable();
   6598		__schedule(SM_RTLOCK_WAIT);
   6599		sched_preempt_enable_no_resched();
   6600	} while (need_resched());
   6601}
   6602NOKPROBE_SYMBOL(schedule_rtlock);
   6603#endif
   6604
   6605static void __sched notrace preempt_schedule_common(void)
   6606{
   6607	do {
   6608		/*
   6609		 * Because the function tracer can trace preempt_count_sub()
   6610		 * and it also uses preempt_enable/disable_notrace(), if
   6611		 * NEED_RESCHED is set, the preempt_enable_notrace() called
   6612		 * by the function tracer will call this function again and
   6613		 * cause infinite recursion.
   6614		 *
   6615		 * Preemption must be disabled here before the function
   6616		 * tracer can trace. Break up preempt_disable() into two
   6617		 * calls. One to disable preemption without fear of being
   6618		 * traced. The other to still record the preemption latency,
   6619		 * which can also be traced by the function tracer.
   6620		 */
   6621		preempt_disable_notrace();
   6622		preempt_latency_start(1);
   6623		__schedule(SM_PREEMPT);
   6624		preempt_latency_stop(1);
   6625		preempt_enable_no_resched_notrace();
   6626
   6627		/*
   6628		 * Check again in case we missed a preemption opportunity
   6629		 * between schedule and now.
   6630		 */
   6631	} while (need_resched());
   6632}
   6633
   6634#ifdef CONFIG_PREEMPTION
   6635/*
   6636 * This is the entry point to schedule() from in-kernel preemption
   6637 * off of preempt_enable.
   6638 */
   6639asmlinkage __visible void __sched notrace preempt_schedule(void)
   6640{
   6641	/*
   6642	 * If there is a non-zero preempt_count or interrupts are disabled,
   6643	 * we do not want to preempt the current task. Just return..
   6644	 */
   6645	if (likely(!preemptible()))
   6646		return;
   6647	preempt_schedule_common();
   6648}
   6649NOKPROBE_SYMBOL(preempt_schedule);
   6650EXPORT_SYMBOL(preempt_schedule);
   6651
   6652#ifdef CONFIG_PREEMPT_DYNAMIC
   6653#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
   6654#ifndef preempt_schedule_dynamic_enabled
   6655#define preempt_schedule_dynamic_enabled	preempt_schedule
   6656#define preempt_schedule_dynamic_disabled	NULL
   6657#endif
   6658DEFINE_STATIC_CALL(preempt_schedule, preempt_schedule_dynamic_enabled);
   6659EXPORT_STATIC_CALL_TRAMP(preempt_schedule);
   6660#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
   6661static DEFINE_STATIC_KEY_TRUE(sk_dynamic_preempt_schedule);
   6662void __sched notrace dynamic_preempt_schedule(void)
   6663{
   6664	if (!static_branch_unlikely(&sk_dynamic_preempt_schedule))
   6665		return;
   6666	preempt_schedule();
   6667}
   6668NOKPROBE_SYMBOL(dynamic_preempt_schedule);
   6669EXPORT_SYMBOL(dynamic_preempt_schedule);
   6670#endif
   6671#endif
   6672
   6673/**
   6674 * preempt_schedule_notrace - preempt_schedule called by tracing
   6675 *
   6676 * The tracing infrastructure uses preempt_enable_notrace to prevent
   6677 * recursion and tracing preempt enabling caused by the tracing
   6678 * infrastructure itself. But as tracing can happen in areas coming
   6679 * from userspace or just about to enter userspace, a preempt enable
   6680 * can occur before user_exit() is called. This will cause the scheduler
   6681 * to be called when the system is still in usermode.
   6682 *
   6683 * To prevent this, the preempt_enable_notrace will use this function
   6684 * instead of preempt_schedule() to exit user context if needed before
   6685 * calling the scheduler.
   6686 */
   6687asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
   6688{
   6689	enum ctx_state prev_ctx;
   6690
   6691	if (likely(!preemptible()))
   6692		return;
   6693
   6694	do {
   6695		/*
   6696		 * Because the function tracer can trace preempt_count_sub()
   6697		 * and it also uses preempt_enable/disable_notrace(), if
   6698		 * NEED_RESCHED is set, the preempt_enable_notrace() called
   6699		 * by the function tracer will call this function again and
   6700		 * cause infinite recursion.
   6701		 *
   6702		 * Preemption must be disabled here before the function
   6703		 * tracer can trace. Break up preempt_disable() into two
   6704		 * calls. One to disable preemption without fear of being
   6705		 * traced. The other to still record the preemption latency,
   6706		 * which can also be traced by the function tracer.
   6707		 */
   6708		preempt_disable_notrace();
   6709		preempt_latency_start(1);
   6710		/*
   6711		 * Needs preempt disabled in case user_exit() is traced
   6712		 * and the tracer calls preempt_enable_notrace() causing
   6713		 * an infinite recursion.
   6714		 */
   6715		prev_ctx = exception_enter();
   6716		__schedule(SM_PREEMPT);
   6717		exception_exit(prev_ctx);
   6718
   6719		preempt_latency_stop(1);
   6720		preempt_enable_no_resched_notrace();
   6721	} while (need_resched());
   6722}
   6723EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
   6724
   6725#ifdef CONFIG_PREEMPT_DYNAMIC
   6726#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
   6727#ifndef preempt_schedule_notrace_dynamic_enabled
   6728#define preempt_schedule_notrace_dynamic_enabled	preempt_schedule_notrace
   6729#define preempt_schedule_notrace_dynamic_disabled	NULL
   6730#endif
   6731DEFINE_STATIC_CALL(preempt_schedule_notrace, preempt_schedule_notrace_dynamic_enabled);
   6732EXPORT_STATIC_CALL_TRAMP(preempt_schedule_notrace);
   6733#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
   6734static DEFINE_STATIC_KEY_TRUE(sk_dynamic_preempt_schedule_notrace);
   6735void __sched notrace dynamic_preempt_schedule_notrace(void)
   6736{
   6737	if (!static_branch_unlikely(&sk_dynamic_preempt_schedule_notrace))
   6738		return;
   6739	preempt_schedule_notrace();
   6740}
   6741NOKPROBE_SYMBOL(dynamic_preempt_schedule_notrace);
   6742EXPORT_SYMBOL(dynamic_preempt_schedule_notrace);
   6743#endif
   6744#endif
   6745
   6746#endif /* CONFIG_PREEMPTION */
   6747
   6748/*
   6749 * This is the entry point to schedule() from kernel preemption
   6750 * off of irq context.
   6751 * Note, that this is called and return with irqs disabled. This will
   6752 * protect us against recursive calling from irq.
   6753 */
   6754asmlinkage __visible void __sched preempt_schedule_irq(void)
   6755{
   6756	enum ctx_state prev_state;
   6757
   6758	/* Catch callers which need to be fixed */
   6759	BUG_ON(preempt_count() || !irqs_disabled());
   6760
   6761	prev_state = exception_enter();
   6762
   6763	do {
   6764		preempt_disable();
   6765		local_irq_enable();
   6766		__schedule(SM_PREEMPT);
   6767		local_irq_disable();
   6768		sched_preempt_enable_no_resched();
   6769	} while (need_resched());
   6770
   6771	exception_exit(prev_state);
   6772}
   6773
   6774int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags,
   6775			  void *key)
   6776{
   6777	WARN_ON_ONCE(IS_ENABLED(CONFIG_SCHED_DEBUG) && wake_flags & ~WF_SYNC);
   6778	return try_to_wake_up(curr->private, mode, wake_flags);
   6779}
   6780EXPORT_SYMBOL(default_wake_function);
   6781
   6782static void __setscheduler_prio(struct task_struct *p, int prio)
   6783{
   6784	if (dl_prio(prio))
   6785		p->sched_class = &dl_sched_class;
   6786	else if (rt_prio(prio))
   6787		p->sched_class = &rt_sched_class;
   6788	else
   6789		p->sched_class = &fair_sched_class;
   6790
   6791	p->prio = prio;
   6792}
   6793
   6794#ifdef CONFIG_RT_MUTEXES
   6795
   6796static inline int __rt_effective_prio(struct task_struct *pi_task, int prio)
   6797{
   6798	if (pi_task)
   6799		prio = min(prio, pi_task->prio);
   6800
   6801	return prio;
   6802}
   6803
   6804static inline int rt_effective_prio(struct task_struct *p, int prio)
   6805{
   6806	struct task_struct *pi_task = rt_mutex_get_top_task(p);
   6807
   6808	return __rt_effective_prio(pi_task, prio);
   6809}
   6810
   6811/*
   6812 * rt_mutex_setprio - set the current priority of a task
   6813 * @p: task to boost
   6814 * @pi_task: donor task
   6815 *
   6816 * This function changes the 'effective' priority of a task. It does
   6817 * not touch ->normal_prio like __setscheduler().
   6818 *
   6819 * Used by the rt_mutex code to implement priority inheritance
   6820 * logic. Call site only calls if the priority of the task changed.
   6821 */
   6822void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
   6823{
   6824	int prio, oldprio, queued, running, queue_flag =
   6825		DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
   6826	const struct sched_class *prev_class;
   6827	struct rq_flags rf;
   6828	struct rq *rq;
   6829
   6830	/* XXX used to be waiter->prio, not waiter->task->prio */
   6831	prio = __rt_effective_prio(pi_task, p->normal_prio);
   6832
   6833	/*
   6834	 * If nothing changed; bail early.
   6835	 */
   6836	if (p->pi_top_task == pi_task && prio == p->prio && !dl_prio(prio))
   6837		return;
   6838
   6839	rq = __task_rq_lock(p, &rf);
   6840	update_rq_clock(rq);
   6841	/*
   6842	 * Set under pi_lock && rq->lock, such that the value can be used under
   6843	 * either lock.
   6844	 *
   6845	 * Note that there is loads of tricky to make this pointer cache work
   6846	 * right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to
   6847	 * ensure a task is de-boosted (pi_task is set to NULL) before the
   6848	 * task is allowed to run again (and can exit). This ensures the pointer
   6849	 * points to a blocked task -- which guarantees the task is present.
   6850	 */
   6851	p->pi_top_task = pi_task;
   6852
   6853	/*
   6854	 * For FIFO/RR we only need to set prio, if that matches we're done.
   6855	 */
   6856	if (prio == p->prio && !dl_prio(prio))
   6857		goto out_unlock;
   6858
   6859	/*
   6860	 * Idle task boosting is a nono in general. There is one
   6861	 * exception, when PREEMPT_RT and NOHZ is active:
   6862	 *
   6863	 * The idle task calls get_next_timer_interrupt() and holds
   6864	 * the timer wheel base->lock on the CPU and another CPU wants
   6865	 * to access the timer (probably to cancel it). We can safely
   6866	 * ignore the boosting request, as the idle CPU runs this code
   6867	 * with interrupts disabled and will complete the lock
   6868	 * protected section without being interrupted. So there is no
   6869	 * real need to boost.
   6870	 */
   6871	if (unlikely(p == rq->idle)) {
   6872		WARN_ON(p != rq->curr);
   6873		WARN_ON(p->pi_blocked_on);
   6874		goto out_unlock;
   6875	}
   6876
   6877	trace_sched_pi_setprio(p, pi_task);
   6878	oldprio = p->prio;
   6879
   6880	if (oldprio == prio)
   6881		queue_flag &= ~DEQUEUE_MOVE;
   6882
   6883	prev_class = p->sched_class;
   6884	queued = task_on_rq_queued(p);
   6885	running = task_current(rq, p);
   6886	if (queued)
   6887		dequeue_task(rq, p, queue_flag);
   6888	if (running)
   6889		put_prev_task(rq, p);
   6890
   6891	/*
   6892	 * Boosting condition are:
   6893	 * 1. -rt task is running and holds mutex A
   6894	 *      --> -dl task blocks on mutex A
   6895	 *
   6896	 * 2. -dl task is running and holds mutex A
   6897	 *      --> -dl task blocks on mutex A and could preempt the
   6898	 *          running task
   6899	 */
   6900	if (dl_prio(prio)) {
   6901		if (!dl_prio(p->normal_prio) ||
   6902		    (pi_task && dl_prio(pi_task->prio) &&
   6903		     dl_entity_preempt(&pi_task->dl, &p->dl))) {
   6904			p->dl.pi_se = pi_task->dl.pi_se;
   6905			queue_flag |= ENQUEUE_REPLENISH;
   6906		} else {
   6907			p->dl.pi_se = &p->dl;
   6908		}
   6909	} else if (rt_prio(prio)) {
   6910		if (dl_prio(oldprio))
   6911			p->dl.pi_se = &p->dl;
   6912		if (oldprio < prio)
   6913			queue_flag |= ENQUEUE_HEAD;
   6914	} else {
   6915		if (dl_prio(oldprio))
   6916			p->dl.pi_se = &p->dl;
   6917		if (rt_prio(oldprio))
   6918			p->rt.timeout = 0;
   6919	}
   6920
   6921	__setscheduler_prio(p, prio);
   6922
   6923	if (queued)
   6924		enqueue_task(rq, p, queue_flag);
   6925	if (running)
   6926		set_next_task(rq, p);
   6927
   6928	check_class_changed(rq, p, prev_class, oldprio);
   6929out_unlock:
   6930	/* Avoid rq from going away on us: */
   6931	preempt_disable();
   6932
   6933	rq_unpin_lock(rq, &rf);
   6934	__balance_callbacks(rq);
   6935	raw_spin_rq_unlock(rq);
   6936
   6937	preempt_enable();
   6938}
   6939#else
   6940static inline int rt_effective_prio(struct task_struct *p, int prio)
   6941{
   6942	return prio;
   6943}
   6944#endif
   6945
   6946void set_user_nice(struct task_struct *p, long nice)
   6947{
   6948	bool queued, running;
   6949	int old_prio;
   6950	struct rq_flags rf;
   6951	struct rq *rq;
   6952
   6953	if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
   6954		return;
   6955	/*
   6956	 * We have to be careful, if called from sys_setpriority(),
   6957	 * the task might be in the middle of scheduling on another CPU.
   6958	 */
   6959	rq = task_rq_lock(p, &rf);
   6960	update_rq_clock(rq);
   6961
   6962	/*
   6963	 * The RT priorities are set via sched_setscheduler(), but we still
   6964	 * allow the 'normal' nice value to be set - but as expected
   6965	 * it won't have any effect on scheduling until the task is
   6966	 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
   6967	 */
   6968	if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
   6969		p->static_prio = NICE_TO_PRIO(nice);
   6970		goto out_unlock;
   6971	}
   6972	queued = task_on_rq_queued(p);
   6973	running = task_current(rq, p);
   6974	if (queued)
   6975		dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
   6976	if (running)
   6977		put_prev_task(rq, p);
   6978
   6979	p->static_prio = NICE_TO_PRIO(nice);
   6980	set_load_weight(p, true);
   6981	old_prio = p->prio;
   6982	p->prio = effective_prio(p);
   6983
   6984	if (queued)
   6985		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
   6986	if (running)
   6987		set_next_task(rq, p);
   6988
   6989	/*
   6990	 * If the task increased its priority or is running and
   6991	 * lowered its priority, then reschedule its CPU:
   6992	 */
   6993	p->sched_class->prio_changed(rq, p, old_prio);
   6994
   6995out_unlock:
   6996	task_rq_unlock(rq, p, &rf);
   6997}
   6998EXPORT_SYMBOL(set_user_nice);
   6999
   7000/*
   7001 * can_nice - check if a task can reduce its nice value
   7002 * @p: task
   7003 * @nice: nice value
   7004 */
   7005int can_nice(const struct task_struct *p, const int nice)
   7006{
   7007	/* Convert nice value [19,-20] to rlimit style value [1,40]: */
   7008	int nice_rlim = nice_to_rlimit(nice);
   7009
   7010	return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
   7011		capable(CAP_SYS_NICE));
   7012}
   7013
   7014#ifdef __ARCH_WANT_SYS_NICE
   7015
   7016/*
   7017 * sys_nice - change the priority of the current process.
   7018 * @increment: priority increment
   7019 *
   7020 * sys_setpriority is a more generic, but much slower function that
   7021 * does similar things.
   7022 */
   7023SYSCALL_DEFINE1(nice, int, increment)
   7024{
   7025	long nice, retval;
   7026
   7027	/*
   7028	 * Setpriority might change our priority at the same moment.
   7029	 * We don't have to worry. Conceptually one call occurs first
   7030	 * and we have a single winner.
   7031	 */
   7032	increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
   7033	nice = task_nice(current) + increment;
   7034
   7035	nice = clamp_val(nice, MIN_NICE, MAX_NICE);
   7036	if (increment < 0 && !can_nice(current, nice))
   7037		return -EPERM;
   7038
   7039	retval = security_task_setnice(current, nice);
   7040	if (retval)
   7041		return retval;
   7042
   7043	set_user_nice(current, nice);
   7044	return 0;
   7045}
   7046
   7047#endif
   7048
   7049/**
   7050 * task_prio - return the priority value of a given task.
   7051 * @p: the task in question.
   7052 *
   7053 * Return: The priority value as seen by users in /proc.
   7054 *
   7055 * sched policy         return value   kernel prio    user prio/nice
   7056 *
   7057 * normal, batch, idle     [0 ... 39]  [100 ... 139]          0/[-20 ... 19]
   7058 * fifo, rr             [-2 ... -100]     [98 ... 0]  [1 ... 99]
   7059 * deadline                     -101             -1           0
   7060 */
   7061int task_prio(const struct task_struct *p)
   7062{
   7063	return p->prio - MAX_RT_PRIO;
   7064}
   7065
   7066/**
   7067 * idle_cpu - is a given CPU idle currently?
   7068 * @cpu: the processor in question.
   7069 *
   7070 * Return: 1 if the CPU is currently idle. 0 otherwise.
   7071 */
   7072int idle_cpu(int cpu)
   7073{
   7074	struct rq *rq = cpu_rq(cpu);
   7075
   7076	if (rq->curr != rq->idle)
   7077		return 0;
   7078
   7079	if (rq->nr_running)
   7080		return 0;
   7081
   7082#ifdef CONFIG_SMP
   7083	if (rq->ttwu_pending)
   7084		return 0;
   7085#endif
   7086
   7087	return 1;
   7088}
   7089
   7090/**
   7091 * available_idle_cpu - is a given CPU idle for enqueuing work.
   7092 * @cpu: the CPU in question.
   7093 *
   7094 * Return: 1 if the CPU is currently idle. 0 otherwise.
   7095 */
   7096int available_idle_cpu(int cpu)
   7097{
   7098	if (!idle_cpu(cpu))
   7099		return 0;
   7100
   7101	if (vcpu_is_preempted(cpu))
   7102		return 0;
   7103
   7104	return 1;
   7105}
   7106
   7107/**
   7108 * idle_task - return the idle task for a given CPU.
   7109 * @cpu: the processor in question.
   7110 *
   7111 * Return: The idle task for the CPU @cpu.
   7112 */
   7113struct task_struct *idle_task(int cpu)
   7114{
   7115	return cpu_rq(cpu)->idle;
   7116}
   7117
   7118#ifdef CONFIG_SMP
   7119/*
   7120 * This function computes an effective utilization for the given CPU, to be
   7121 * used for frequency selection given the linear relation: f = u * f_max.
   7122 *
   7123 * The scheduler tracks the following metrics:
   7124 *
   7125 *   cpu_util_{cfs,rt,dl,irq}()
   7126 *   cpu_bw_dl()
   7127 *
   7128 * Where the cfs,rt and dl util numbers are tracked with the same metric and
   7129 * synchronized windows and are thus directly comparable.
   7130 *
   7131 * The cfs,rt,dl utilization are the running times measured with rq->clock_task
   7132 * which excludes things like IRQ and steal-time. These latter are then accrued
   7133 * in the irq utilization.
   7134 *
   7135 * The DL bandwidth number otoh is not a measured metric but a value computed
   7136 * based on the task model parameters and gives the minimal utilization
   7137 * required to meet deadlines.
   7138 */
   7139unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
   7140				 unsigned long max, enum cpu_util_type type,
   7141				 struct task_struct *p)
   7142{
   7143	unsigned long dl_util, util, irq;
   7144	struct rq *rq = cpu_rq(cpu);
   7145
   7146	if (!uclamp_is_used() &&
   7147	    type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
   7148		return max;
   7149	}
   7150
   7151	/*
   7152	 * Early check to see if IRQ/steal time saturates the CPU, can be
   7153	 * because of inaccuracies in how we track these -- see
   7154	 * update_irq_load_avg().
   7155	 */
   7156	irq = cpu_util_irq(rq);
   7157	if (unlikely(irq >= max))
   7158		return max;
   7159
   7160	/*
   7161	 * Because the time spend on RT/DL tasks is visible as 'lost' time to
   7162	 * CFS tasks and we use the same metric to track the effective
   7163	 * utilization (PELT windows are synchronized) we can directly add them
   7164	 * to obtain the CPU's actual utilization.
   7165	 *
   7166	 * CFS and RT utilization can be boosted or capped, depending on
   7167	 * utilization clamp constraints requested by currently RUNNABLE
   7168	 * tasks.
   7169	 * When there are no CFS RUNNABLE tasks, clamps are released and
   7170	 * frequency will be gracefully reduced with the utilization decay.
   7171	 */
   7172	util = util_cfs + cpu_util_rt(rq);
   7173	if (type == FREQUENCY_UTIL)
   7174		util = uclamp_rq_util_with(rq, util, p);
   7175
   7176	dl_util = cpu_util_dl(rq);
   7177
   7178	/*
   7179	 * For frequency selection we do not make cpu_util_dl() a permanent part
   7180	 * of this sum because we want to use cpu_bw_dl() later on, but we need
   7181	 * to check if the CFS+RT+DL sum is saturated (ie. no idle time) such
   7182	 * that we select f_max when there is no idle time.
   7183	 *
   7184	 * NOTE: numerical errors or stop class might cause us to not quite hit
   7185	 * saturation when we should -- something for later.
   7186	 */
   7187	if (util + dl_util >= max)
   7188		return max;
   7189
   7190	/*
   7191	 * OTOH, for energy computation we need the estimated running time, so
   7192	 * include util_dl and ignore dl_bw.
   7193	 */
   7194	if (type == ENERGY_UTIL)
   7195		util += dl_util;
   7196
   7197	/*
   7198	 * There is still idle time; further improve the number by using the
   7199	 * irq metric. Because IRQ/steal time is hidden from the task clock we
   7200	 * need to scale the task numbers:
   7201	 *
   7202	 *              max - irq
   7203	 *   U' = irq + --------- * U
   7204	 *                 max
   7205	 */
   7206	util = scale_irq_capacity(util, irq, max);
   7207	util += irq;
   7208
   7209	/*
   7210	 * Bandwidth required by DEADLINE must always be granted while, for
   7211	 * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism
   7212	 * to gracefully reduce the frequency when no tasks show up for longer
   7213	 * periods of time.
   7214	 *
   7215	 * Ideally we would like to set bw_dl as min/guaranteed freq and util +
   7216	 * bw_dl as requested freq. However, cpufreq is not yet ready for such
   7217	 * an interface. So, we only do the latter for now.
   7218	 */
   7219	if (type == FREQUENCY_UTIL)
   7220		util += cpu_bw_dl(rq);
   7221
   7222	return min(max, util);
   7223}
   7224
   7225unsigned long sched_cpu_util(int cpu, unsigned long max)
   7226{
   7227	return effective_cpu_util(cpu, cpu_util_cfs(cpu), max,
   7228				  ENERGY_UTIL, NULL);
   7229}
   7230#endif /* CONFIG_SMP */
   7231
   7232/**
   7233 * find_process_by_pid - find a process with a matching PID value.
   7234 * @pid: the pid in question.
   7235 *
   7236 * The task of @pid, if found. %NULL otherwise.
   7237 */
   7238static struct task_struct *find_process_by_pid(pid_t pid)
   7239{
   7240	return pid ? find_task_by_vpid(pid) : current;
   7241}
   7242
   7243/*
   7244 * sched_setparam() passes in -1 for its policy, to let the functions
   7245 * it calls know not to change it.
   7246 */
   7247#define SETPARAM_POLICY	-1
   7248
   7249static void __setscheduler_params(struct task_struct *p,
   7250		const struct sched_attr *attr)
   7251{
   7252	int policy = attr->sched_policy;
   7253
   7254	if (policy == SETPARAM_POLICY)
   7255		policy = p->policy;
   7256
   7257	p->policy = policy;
   7258
   7259	if (dl_policy(policy))
   7260		__setparam_dl(p, attr);
   7261	else if (fair_policy(policy))
   7262		p->static_prio = NICE_TO_PRIO(attr->sched_nice);
   7263
   7264	/*
   7265	 * __sched_setscheduler() ensures attr->sched_priority == 0 when
   7266	 * !rt_policy. Always setting this ensures that things like
   7267	 * getparam()/getattr() don't report silly values for !rt tasks.
   7268	 */
   7269	p->rt_priority = attr->sched_priority;
   7270	p->normal_prio = normal_prio(p);
   7271	set_load_weight(p, true);
   7272}
   7273
   7274/*
   7275 * Check the target process has a UID that matches the current process's:
   7276 */
   7277static bool check_same_owner(struct task_struct *p)
   7278{
   7279	const struct cred *cred = current_cred(), *pcred;
   7280	bool match;
   7281
   7282	rcu_read_lock();
   7283	pcred = __task_cred(p);
   7284	match = (uid_eq(cred->euid, pcred->euid) ||
   7285		 uid_eq(cred->euid, pcred->uid));
   7286	rcu_read_unlock();
   7287	return match;
   7288}
   7289
   7290static int __sched_setscheduler(struct task_struct *p,
   7291				const struct sched_attr *attr,
   7292				bool user, bool pi)
   7293{
   7294	int oldpolicy = -1, policy = attr->sched_policy;
   7295	int retval, oldprio, newprio, queued, running;
   7296	const struct sched_class *prev_class;
   7297	struct callback_head *head;
   7298	struct rq_flags rf;
   7299	int reset_on_fork;
   7300	int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
   7301	struct rq *rq;
   7302
   7303	/* The pi code expects interrupts enabled */
   7304	BUG_ON(pi && in_interrupt());
   7305recheck:
   7306	/* Double check policy once rq lock held: */
   7307	if (policy < 0) {
   7308		reset_on_fork = p->sched_reset_on_fork;
   7309		policy = oldpolicy = p->policy;
   7310	} else {
   7311		reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
   7312
   7313		if (!valid_policy(policy))
   7314			return -EINVAL;
   7315	}
   7316
   7317	if (attr->sched_flags & ~(SCHED_FLAG_ALL | SCHED_FLAG_SUGOV))
   7318		return -EINVAL;
   7319
   7320	/*
   7321	 * Valid priorities for SCHED_FIFO and SCHED_RR are
   7322	 * 1..MAX_RT_PRIO-1, valid priority for SCHED_NORMAL,
   7323	 * SCHED_BATCH and SCHED_IDLE is 0.
   7324	 */
   7325	if (attr->sched_priority > MAX_RT_PRIO-1)
   7326		return -EINVAL;
   7327	if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
   7328	    (rt_policy(policy) != (attr->sched_priority != 0)))
   7329		return -EINVAL;
   7330
   7331	/*
   7332	 * Allow unprivileged RT tasks to decrease priority:
   7333	 */
   7334	if (user && !capable(CAP_SYS_NICE)) {
   7335		if (fair_policy(policy)) {
   7336			if (attr->sched_nice < task_nice(p) &&
   7337			    !can_nice(p, attr->sched_nice))
   7338				return -EPERM;
   7339		}
   7340
   7341		if (rt_policy(policy)) {
   7342			unsigned long rlim_rtprio =
   7343					task_rlimit(p, RLIMIT_RTPRIO);
   7344
   7345			/* Can't set/change the rt policy: */
   7346			if (policy != p->policy && !rlim_rtprio)
   7347				return -EPERM;
   7348
   7349			/* Can't increase priority: */
   7350			if (attr->sched_priority > p->rt_priority &&
   7351			    attr->sched_priority > rlim_rtprio)
   7352				return -EPERM;
   7353		}
   7354
   7355		 /*
   7356		  * Can't set/change SCHED_DEADLINE policy at all for now
   7357		  * (safest behavior); in the future we would like to allow
   7358		  * unprivileged DL tasks to increase their relative deadline
   7359		  * or reduce their runtime (both ways reducing utilization)
   7360		  */
   7361		if (dl_policy(policy))
   7362			return -EPERM;
   7363
   7364		/*
   7365		 * Treat SCHED_IDLE as nice 20. Only allow a switch to
   7366		 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
   7367		 */
   7368		if (task_has_idle_policy(p) && !idle_policy(policy)) {
   7369			if (!can_nice(p, task_nice(p)))
   7370				return -EPERM;
   7371		}
   7372
   7373		/* Can't change other user's priorities: */
   7374		if (!check_same_owner(p))
   7375			return -EPERM;
   7376
   7377		/* Normal users shall not reset the sched_reset_on_fork flag: */
   7378		if (p->sched_reset_on_fork && !reset_on_fork)
   7379			return -EPERM;
   7380	}
   7381
   7382	if (user) {
   7383		if (attr->sched_flags & SCHED_FLAG_SUGOV)
   7384			return -EINVAL;
   7385
   7386		retval = security_task_setscheduler(p);
   7387		if (retval)
   7388			return retval;
   7389	}
   7390
   7391	/* Update task specific "requested" clamps */
   7392	if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) {
   7393		retval = uclamp_validate(p, attr);
   7394		if (retval)
   7395			return retval;
   7396	}
   7397
   7398	if (pi)
   7399		cpuset_read_lock();
   7400
   7401	/*
   7402	 * Make sure no PI-waiters arrive (or leave) while we are
   7403	 * changing the priority of the task:
   7404	 *
   7405	 * To be able to change p->policy safely, the appropriate
   7406	 * runqueue lock must be held.
   7407	 */
   7408	rq = task_rq_lock(p, &rf);
   7409	update_rq_clock(rq);
   7410
   7411	/*
   7412	 * Changing the policy of the stop threads its a very bad idea:
   7413	 */
   7414	if (p == rq->stop) {
   7415		retval = -EINVAL;
   7416		goto unlock;
   7417	}
   7418
   7419	/*
   7420	 * If not changing anything there's no need to proceed further,
   7421	 * but store a possible modification of reset_on_fork.
   7422	 */
   7423	if (unlikely(policy == p->policy)) {
   7424		if (fair_policy(policy) && attr->sched_nice != task_nice(p))
   7425			goto change;
   7426		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
   7427			goto change;
   7428		if (dl_policy(policy) && dl_param_changed(p, attr))
   7429			goto change;
   7430		if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)
   7431			goto change;
   7432
   7433		p->sched_reset_on_fork = reset_on_fork;
   7434		retval = 0;
   7435		goto unlock;
   7436	}
   7437change:
   7438
   7439	if (user) {
   7440#ifdef CONFIG_RT_GROUP_SCHED
   7441		/*
   7442		 * Do not allow realtime tasks into groups that have no runtime
   7443		 * assigned.
   7444		 */
   7445		if (rt_bandwidth_enabled() && rt_policy(policy) &&
   7446				task_group(p)->rt_bandwidth.rt_runtime == 0 &&
   7447				!task_group_is_autogroup(task_group(p))) {
   7448			retval = -EPERM;
   7449			goto unlock;
   7450		}
   7451#endif
   7452#ifdef CONFIG_SMP
   7453		if (dl_bandwidth_enabled() && dl_policy(policy) &&
   7454				!(attr->sched_flags & SCHED_FLAG_SUGOV)) {
   7455			cpumask_t *span = rq->rd->span;
   7456
   7457			/*
   7458			 * Don't allow tasks with an affinity mask smaller than
   7459			 * the entire root_domain to become SCHED_DEADLINE. We
   7460			 * will also fail if there's no bandwidth available.
   7461			 */
   7462			if (!cpumask_subset(span, p->cpus_ptr) ||
   7463			    rq->rd->dl_bw.bw == 0) {
   7464				retval = -EPERM;
   7465				goto unlock;
   7466			}
   7467		}
   7468#endif
   7469	}
   7470
   7471	/* Re-check policy now with rq lock held: */
   7472	if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
   7473		policy = oldpolicy = -1;
   7474		task_rq_unlock(rq, p, &rf);
   7475		if (pi)
   7476			cpuset_read_unlock();
   7477		goto recheck;
   7478	}
   7479
   7480	/*
   7481	 * If setscheduling to SCHED_DEADLINE (or changing the parameters
   7482	 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
   7483	 * is available.
   7484	 */
   7485	if ((dl_policy(policy) || dl_task(p)) && sched_dl_overflow(p, policy, attr)) {
   7486		retval = -EBUSY;
   7487		goto unlock;
   7488	}
   7489
   7490	p->sched_reset_on_fork = reset_on_fork;
   7491	oldprio = p->prio;
   7492
   7493	newprio = __normal_prio(policy, attr->sched_priority, attr->sched_nice);
   7494	if (pi) {
   7495		/*
   7496		 * Take priority boosted tasks into account. If the new
   7497		 * effective priority is unchanged, we just store the new
   7498		 * normal parameters and do not touch the scheduler class and
   7499		 * the runqueue. This will be done when the task deboost
   7500		 * itself.
   7501		 */
   7502		newprio = rt_effective_prio(p, newprio);
   7503		if (newprio == oldprio)
   7504			queue_flags &= ~DEQUEUE_MOVE;
   7505	}
   7506
   7507	queued = task_on_rq_queued(p);
   7508	running = task_current(rq, p);
   7509	if (queued)
   7510		dequeue_task(rq, p, queue_flags);
   7511	if (running)
   7512		put_prev_task(rq, p);
   7513
   7514	prev_class = p->sched_class;
   7515
   7516	if (!(attr->sched_flags & SCHED_FLAG_KEEP_PARAMS)) {
   7517		__setscheduler_params(p, attr);
   7518		__setscheduler_prio(p, newprio);
   7519	}
   7520	__setscheduler_uclamp(p, attr);
   7521
   7522	if (queued) {
   7523		/*
   7524		 * We enqueue to tail when the priority of a task is
   7525		 * increased (user space view).
   7526		 */
   7527		if (oldprio < p->prio)
   7528			queue_flags |= ENQUEUE_HEAD;
   7529
   7530		enqueue_task(rq, p, queue_flags);
   7531	}
   7532	if (running)
   7533		set_next_task(rq, p);
   7534
   7535	check_class_changed(rq, p, prev_class, oldprio);
   7536
   7537	/* Avoid rq from going away on us: */
   7538	preempt_disable();
   7539	head = splice_balance_callbacks(rq);
   7540	task_rq_unlock(rq, p, &rf);
   7541
   7542	if (pi) {
   7543		cpuset_read_unlock();
   7544		rt_mutex_adjust_pi(p);
   7545	}
   7546
   7547	/* Run balance callbacks after we've adjusted the PI chain: */
   7548	balance_callbacks(rq, head);
   7549	preempt_enable();
   7550
   7551	return 0;
   7552
   7553unlock:
   7554	task_rq_unlock(rq, p, &rf);
   7555	if (pi)
   7556		cpuset_read_unlock();
   7557	return retval;
   7558}
   7559
   7560static int _sched_setscheduler(struct task_struct *p, int policy,
   7561			       const struct sched_param *param, bool check)
   7562{
   7563	struct sched_attr attr = {
   7564		.sched_policy   = policy,
   7565		.sched_priority = param->sched_priority,
   7566		.sched_nice	= PRIO_TO_NICE(p->static_prio),
   7567	};
   7568
   7569	/* Fixup the legacy SCHED_RESET_ON_FORK hack. */
   7570	if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
   7571		attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
   7572		policy &= ~SCHED_RESET_ON_FORK;
   7573		attr.sched_policy = policy;
   7574	}
   7575
   7576	return __sched_setscheduler(p, &attr, check, true);
   7577}
   7578/**
   7579 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
   7580 * @p: the task in question.
   7581 * @policy: new policy.
   7582 * @param: structure containing the new RT priority.
   7583 *
   7584 * Use sched_set_fifo(), read its comment.
   7585 *
   7586 * Return: 0 on success. An error code otherwise.
   7587 *
   7588 * NOTE that the task may be already dead.
   7589 */
   7590int sched_setscheduler(struct task_struct *p, int policy,
   7591		       const struct sched_param *param)
   7592{
   7593	return _sched_setscheduler(p, policy, param, true);
   7594}
   7595
   7596int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
   7597{
   7598	return __sched_setscheduler(p, attr, true, true);
   7599}
   7600
   7601int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr)
   7602{
   7603	return __sched_setscheduler(p, attr, false, true);
   7604}
   7605EXPORT_SYMBOL_GPL(sched_setattr_nocheck);
   7606
   7607/**
   7608 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
   7609 * @p: the task in question.
   7610 * @policy: new policy.
   7611 * @param: structure containing the new RT priority.
   7612 *
   7613 * Just like sched_setscheduler, only don't bother checking if the
   7614 * current context has permission.  For example, this is needed in
   7615 * stop_machine(): we create temporary high priority worker threads,
   7616 * but our caller might not have that capability.
   7617 *
   7618 * Return: 0 on success. An error code otherwise.
   7619 */
   7620int sched_setscheduler_nocheck(struct task_struct *p, int policy,
   7621			       const struct sched_param *param)
   7622{
   7623	return _sched_setscheduler(p, policy, param, false);
   7624}
   7625
   7626/*
   7627 * SCHED_FIFO is a broken scheduler model; that is, it is fundamentally
   7628 * incapable of resource management, which is the one thing an OS really should
   7629 * be doing.
   7630 *
   7631 * This is of course the reason it is limited to privileged users only.
   7632 *
   7633 * Worse still; it is fundamentally impossible to compose static priority
   7634 * workloads. You cannot take two correctly working static prio workloads
   7635 * and smash them together and still expect them to work.
   7636 *
   7637 * For this reason 'all' FIFO tasks the kernel creates are basically at:
   7638 *
   7639 *   MAX_RT_PRIO / 2
   7640 *
   7641 * The administrator _MUST_ configure the system, the kernel simply doesn't
   7642 * know enough information to make a sensible choice.
   7643 */
   7644void sched_set_fifo(struct task_struct *p)
   7645{
   7646	struct sched_param sp = { .sched_priority = MAX_RT_PRIO / 2 };
   7647	WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0);
   7648}
   7649EXPORT_SYMBOL_GPL(sched_set_fifo);
   7650
   7651/*
   7652 * For when you don't much care about FIFO, but want to be above SCHED_NORMAL.
   7653 */
   7654void sched_set_fifo_low(struct task_struct *p)
   7655{
   7656	struct sched_param sp = { .sched_priority = 1 };
   7657	WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0);
   7658}
   7659EXPORT_SYMBOL_GPL(sched_set_fifo_low);
   7660
   7661void sched_set_normal(struct task_struct *p, int nice)
   7662{
   7663	struct sched_attr attr = {
   7664		.sched_policy = SCHED_NORMAL,
   7665		.sched_nice = nice,
   7666	};
   7667	WARN_ON_ONCE(sched_setattr_nocheck(p, &attr) != 0);
   7668}
   7669EXPORT_SYMBOL_GPL(sched_set_normal);
   7670
   7671static int
   7672do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
   7673{
   7674	struct sched_param lparam;
   7675	struct task_struct *p;
   7676	int retval;
   7677
   7678	if (!param || pid < 0)
   7679		return -EINVAL;
   7680	if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
   7681		return -EFAULT;
   7682
   7683	rcu_read_lock();
   7684	retval = -ESRCH;
   7685	p = find_process_by_pid(pid);
   7686	if (likely(p))
   7687		get_task_struct(p);
   7688	rcu_read_unlock();
   7689
   7690	if (likely(p)) {
   7691		retval = sched_setscheduler(p, policy, &lparam);
   7692		put_task_struct(p);
   7693	}
   7694
   7695	return retval;
   7696}
   7697
   7698/*
   7699 * Mimics kernel/events/core.c perf_copy_attr().
   7700 */
   7701static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr)
   7702{
   7703	u32 size;
   7704	int ret;
   7705
   7706	/* Zero the full structure, so that a short copy will be nice: */
   7707	memset(attr, 0, sizeof(*attr));
   7708
   7709	ret = get_user(size, &uattr->size);
   7710	if (ret)
   7711		return ret;
   7712
   7713	/* ABI compatibility quirk: */
   7714	if (!size)
   7715		size = SCHED_ATTR_SIZE_VER0;
   7716	if (size < SCHED_ATTR_SIZE_VER0 || size > PAGE_SIZE)
   7717		goto err_size;
   7718
   7719	ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size);
   7720	if (ret) {
   7721		if (ret == -E2BIG)
   7722			goto err_size;
   7723		return ret;
   7724	}
   7725
   7726	if ((attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) &&
   7727	    size < SCHED_ATTR_SIZE_VER1)
   7728		return -EINVAL;
   7729
   7730	/*
   7731	 * XXX: Do we want to be lenient like existing syscalls; or do we want
   7732	 * to be strict and return an error on out-of-bounds values?
   7733	 */
   7734	attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
   7735
   7736	return 0;
   7737
   7738err_size:
   7739	put_user(sizeof(*attr), &uattr->size);
   7740	return -E2BIG;
   7741}
   7742
   7743static void get_params(struct task_struct *p, struct sched_attr *attr)
   7744{
   7745	if (task_has_dl_policy(p))
   7746		__getparam_dl(p, attr);
   7747	else if (task_has_rt_policy(p))
   7748		attr->sched_priority = p->rt_priority;
   7749	else
   7750		attr->sched_nice = task_nice(p);
   7751}
   7752
   7753/**
   7754 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
   7755 * @pid: the pid in question.
   7756 * @policy: new policy.
   7757 * @param: structure containing the new RT priority.
   7758 *
   7759 * Return: 0 on success. An error code otherwise.
   7760 */
   7761SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, struct sched_param __user *, param)
   7762{
   7763	if (policy < 0)
   7764		return -EINVAL;
   7765
   7766	return do_sched_setscheduler(pid, policy, param);
   7767}
   7768
   7769/**
   7770 * sys_sched_setparam - set/change the RT priority of a thread
   7771 * @pid: the pid in question.
   7772 * @param: structure containing the new RT priority.
   7773 *
   7774 * Return: 0 on success. An error code otherwise.
   7775 */
   7776SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
   7777{
   7778	return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
   7779}
   7780
   7781/**
   7782 * sys_sched_setattr - same as above, but with extended sched_attr
   7783 * @pid: the pid in question.
   7784 * @uattr: structure containing the extended parameters.
   7785 * @flags: for future extension.
   7786 */
   7787SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
   7788			       unsigned int, flags)
   7789{
   7790	struct sched_attr attr;
   7791	struct task_struct *p;
   7792	int retval;
   7793
   7794	if (!uattr || pid < 0 || flags)
   7795		return -EINVAL;
   7796
   7797	retval = sched_copy_attr(uattr, &attr);
   7798	if (retval)
   7799		return retval;
   7800
   7801	if ((int)attr.sched_policy < 0)
   7802		return -EINVAL;
   7803	if (attr.sched_flags & SCHED_FLAG_KEEP_POLICY)
   7804		attr.sched_policy = SETPARAM_POLICY;
   7805
   7806	rcu_read_lock();
   7807	retval = -ESRCH;
   7808	p = find_process_by_pid(pid);
   7809	if (likely(p))
   7810		get_task_struct(p);
   7811	rcu_read_unlock();
   7812
   7813	if (likely(p)) {
   7814		if (attr.sched_flags & SCHED_FLAG_KEEP_PARAMS)
   7815			get_params(p, &attr);
   7816		retval = sched_setattr(p, &attr);
   7817		put_task_struct(p);
   7818	}
   7819
   7820	return retval;
   7821}
   7822
   7823/**
   7824 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
   7825 * @pid: the pid in question.
   7826 *
   7827 * Return: On success, the policy of the thread. Otherwise, a negative error
   7828 * code.
   7829 */
   7830SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
   7831{
   7832	struct task_struct *p;
   7833	int retval;
   7834
   7835	if (pid < 0)
   7836		return -EINVAL;
   7837
   7838	retval = -ESRCH;
   7839	rcu_read_lock();
   7840	p = find_process_by_pid(pid);
   7841	if (p) {
   7842		retval = security_task_getscheduler(p);
   7843		if (!retval)
   7844			retval = p->policy
   7845				| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
   7846	}
   7847	rcu_read_unlock();
   7848	return retval;
   7849}
   7850
   7851/**
   7852 * sys_sched_getparam - get the RT priority of a thread
   7853 * @pid: the pid in question.
   7854 * @param: structure containing the RT priority.
   7855 *
   7856 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
   7857 * code.
   7858 */
   7859SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
   7860{
   7861	struct sched_param lp = { .sched_priority = 0 };
   7862	struct task_struct *p;
   7863	int retval;
   7864
   7865	if (!param || pid < 0)
   7866		return -EINVAL;
   7867
   7868	rcu_read_lock();
   7869	p = find_process_by_pid(pid);
   7870	retval = -ESRCH;
   7871	if (!p)
   7872		goto out_unlock;
   7873
   7874	retval = security_task_getscheduler(p);
   7875	if (retval)
   7876		goto out_unlock;
   7877
   7878	if (task_has_rt_policy(p))
   7879		lp.sched_priority = p->rt_priority;
   7880	rcu_read_unlock();
   7881
   7882	/*
   7883	 * This one might sleep, we cannot do it with a spinlock held ...
   7884	 */
   7885	retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
   7886
   7887	return retval;
   7888
   7889out_unlock:
   7890	rcu_read_unlock();
   7891	return retval;
   7892}
   7893
   7894/*
   7895 * Copy the kernel size attribute structure (which might be larger
   7896 * than what user-space knows about) to user-space.
   7897 *
   7898 * Note that all cases are valid: user-space buffer can be larger or
   7899 * smaller than the kernel-space buffer. The usual case is that both
   7900 * have the same size.
   7901 */
   7902static int
   7903sched_attr_copy_to_user(struct sched_attr __user *uattr,
   7904			struct sched_attr *kattr,
   7905			unsigned int usize)
   7906{
   7907	unsigned int ksize = sizeof(*kattr);
   7908
   7909	if (!access_ok(uattr, usize))
   7910		return -EFAULT;
   7911
   7912	/*
   7913	 * sched_getattr() ABI forwards and backwards compatibility:
   7914	 *
   7915	 * If usize == ksize then we just copy everything to user-space and all is good.
   7916	 *
   7917	 * If usize < ksize then we only copy as much as user-space has space for,
   7918	 * this keeps ABI compatibility as well. We skip the rest.
   7919	 *
   7920	 * If usize > ksize then user-space is using a newer version of the ABI,
   7921	 * which part the kernel doesn't know about. Just ignore it - tooling can
   7922	 * detect the kernel's knowledge of attributes from the attr->size value
   7923	 * which is set to ksize in this case.
   7924	 */
   7925	kattr->size = min(usize, ksize);
   7926
   7927	if (copy_to_user(uattr, kattr, kattr->size))
   7928		return -EFAULT;
   7929
   7930	return 0;
   7931}
   7932
   7933/**
   7934 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
   7935 * @pid: the pid in question.
   7936 * @uattr: structure containing the extended parameters.
   7937 * @usize: sizeof(attr) for fwd/bwd comp.
   7938 * @flags: for future extension.
   7939 */
   7940SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
   7941		unsigned int, usize, unsigned int, flags)
   7942{
   7943	struct sched_attr kattr = { };
   7944	struct task_struct *p;
   7945	int retval;
   7946
   7947	if (!uattr || pid < 0 || usize > PAGE_SIZE ||
   7948	    usize < SCHED_ATTR_SIZE_VER0 || flags)
   7949		return -EINVAL;
   7950
   7951	rcu_read_lock();
   7952	p = find_process_by_pid(pid);
   7953	retval = -ESRCH;
   7954	if (!p)
   7955		goto out_unlock;
   7956
   7957	retval = security_task_getscheduler(p);
   7958	if (retval)
   7959		goto out_unlock;
   7960
   7961	kattr.sched_policy = p->policy;
   7962	if (p->sched_reset_on_fork)
   7963		kattr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
   7964	get_params(p, &kattr);
   7965	kattr.sched_flags &= SCHED_FLAG_ALL;
   7966
   7967#ifdef CONFIG_UCLAMP_TASK
   7968	/*
   7969	 * This could race with another potential updater, but this is fine
   7970	 * because it'll correctly read the old or the new value. We don't need
   7971	 * to guarantee who wins the race as long as it doesn't return garbage.
   7972	 */
   7973	kattr.sched_util_min = p->uclamp_req[UCLAMP_MIN].value;
   7974	kattr.sched_util_max = p->uclamp_req[UCLAMP_MAX].value;
   7975#endif
   7976
   7977	rcu_read_unlock();
   7978
   7979	return sched_attr_copy_to_user(uattr, &kattr, usize);
   7980
   7981out_unlock:
   7982	rcu_read_unlock();
   7983	return retval;
   7984}
   7985
   7986#ifdef CONFIG_SMP
   7987int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask)
   7988{
   7989	int ret = 0;
   7990
   7991	/*
   7992	 * If the task isn't a deadline task or admission control is
   7993	 * disabled then we don't care about affinity changes.
   7994	 */
   7995	if (!task_has_dl_policy(p) || !dl_bandwidth_enabled())
   7996		return 0;
   7997
   7998	/*
   7999	 * Since bandwidth control happens on root_domain basis,
   8000	 * if admission test is enabled, we only admit -deadline
   8001	 * tasks allowed to run on all the CPUs in the task's
   8002	 * root_domain.
   8003	 */
   8004	rcu_read_lock();
   8005	if (!cpumask_subset(task_rq(p)->rd->span, mask))
   8006		ret = -EBUSY;
   8007	rcu_read_unlock();
   8008	return ret;
   8009}
   8010#endif
   8011
   8012static int
   8013__sched_setaffinity(struct task_struct *p, const struct cpumask *mask)
   8014{
   8015	int retval;
   8016	cpumask_var_t cpus_allowed, new_mask;
   8017
   8018	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL))
   8019		return -ENOMEM;
   8020
   8021	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
   8022		retval = -ENOMEM;
   8023		goto out_free_cpus_allowed;
   8024	}
   8025
   8026	cpuset_cpus_allowed(p, cpus_allowed);
   8027	cpumask_and(new_mask, mask, cpus_allowed);
   8028
   8029	retval = dl_task_check_affinity(p, new_mask);
   8030	if (retval)
   8031		goto out_free_new_mask;
   8032again:
   8033	retval = __set_cpus_allowed_ptr(p, new_mask, SCA_CHECK | SCA_USER);
   8034	if (retval)
   8035		goto out_free_new_mask;
   8036
   8037	cpuset_cpus_allowed(p, cpus_allowed);
   8038	if (!cpumask_subset(new_mask, cpus_allowed)) {
   8039		/*
   8040		 * We must have raced with a concurrent cpuset update.
   8041		 * Just reset the cpumask to the cpuset's cpus_allowed.
   8042		 */
   8043		cpumask_copy(new_mask, cpus_allowed);
   8044		goto again;
   8045	}
   8046
   8047out_free_new_mask:
   8048	free_cpumask_var(new_mask);
   8049out_free_cpus_allowed:
   8050	free_cpumask_var(cpus_allowed);
   8051	return retval;
   8052}
   8053
   8054long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
   8055{
   8056	struct task_struct *p;
   8057	int retval;
   8058
   8059	rcu_read_lock();
   8060
   8061	p = find_process_by_pid(pid);
   8062	if (!p) {
   8063		rcu_read_unlock();
   8064		return -ESRCH;
   8065	}
   8066
   8067	/* Prevent p going away */
   8068	get_task_struct(p);
   8069	rcu_read_unlock();
   8070
   8071	if (p->flags & PF_NO_SETAFFINITY) {
   8072		retval = -EINVAL;
   8073		goto out_put_task;
   8074	}
   8075
   8076	if (!check_same_owner(p)) {
   8077		rcu_read_lock();
   8078		if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
   8079			rcu_read_unlock();
   8080			retval = -EPERM;
   8081			goto out_put_task;
   8082		}
   8083		rcu_read_unlock();
   8084	}
   8085
   8086	retval = security_task_setscheduler(p);
   8087	if (retval)
   8088		goto out_put_task;
   8089
   8090	retval = __sched_setaffinity(p, in_mask);
   8091out_put_task:
   8092	put_task_struct(p);
   8093	return retval;
   8094}
   8095
   8096static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
   8097			     struct cpumask *new_mask)
   8098{
   8099	if (len < cpumask_size())
   8100		cpumask_clear(new_mask);
   8101	else if (len > cpumask_size())
   8102		len = cpumask_size();
   8103
   8104	return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
   8105}
   8106
   8107/**
   8108 * sys_sched_setaffinity - set the CPU affinity of a process
   8109 * @pid: pid of the process
   8110 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
   8111 * @user_mask_ptr: user-space pointer to the new CPU mask
   8112 *
   8113 * Return: 0 on success. An error code otherwise.
   8114 */
   8115SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
   8116		unsigned long __user *, user_mask_ptr)
   8117{
   8118	cpumask_var_t new_mask;
   8119	int retval;
   8120
   8121	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
   8122		return -ENOMEM;
   8123
   8124	retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
   8125	if (retval == 0)
   8126		retval = sched_setaffinity(pid, new_mask);
   8127	free_cpumask_var(new_mask);
   8128	return retval;
   8129}
   8130
   8131long sched_getaffinity(pid_t pid, struct cpumask *mask)
   8132{
   8133	struct task_struct *p;
   8134	unsigned long flags;
   8135	int retval;
   8136
   8137	rcu_read_lock();
   8138
   8139	retval = -ESRCH;
   8140	p = find_process_by_pid(pid);
   8141	if (!p)
   8142		goto out_unlock;
   8143
   8144	retval = security_task_getscheduler(p);
   8145	if (retval)
   8146		goto out_unlock;
   8147
   8148	raw_spin_lock_irqsave(&p->pi_lock, flags);
   8149	cpumask_and(mask, &p->cpus_mask, cpu_active_mask);
   8150	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
   8151
   8152out_unlock:
   8153	rcu_read_unlock();
   8154
   8155	return retval;
   8156}
   8157
   8158/**
   8159 * sys_sched_getaffinity - get the CPU affinity of a process
   8160 * @pid: pid of the process
   8161 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
   8162 * @user_mask_ptr: user-space pointer to hold the current CPU mask
   8163 *
   8164 * Return: size of CPU mask copied to user_mask_ptr on success. An
   8165 * error code otherwise.
   8166 */
   8167SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
   8168		unsigned long __user *, user_mask_ptr)
   8169{
   8170	int ret;
   8171	cpumask_var_t mask;
   8172
   8173	if ((len * BITS_PER_BYTE) < nr_cpu_ids)
   8174		return -EINVAL;
   8175	if (len & (sizeof(unsigned long)-1))
   8176		return -EINVAL;
   8177
   8178	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
   8179		return -ENOMEM;
   8180
   8181	ret = sched_getaffinity(pid, mask);
   8182	if (ret == 0) {
   8183		unsigned int retlen = min(len, cpumask_size());
   8184
   8185		if (copy_to_user(user_mask_ptr, mask, retlen))
   8186			ret = -EFAULT;
   8187		else
   8188			ret = retlen;
   8189	}
   8190	free_cpumask_var(mask);
   8191
   8192	return ret;
   8193}
   8194
   8195static void do_sched_yield(void)
   8196{
   8197	struct rq_flags rf;
   8198	struct rq *rq;
   8199
   8200	rq = this_rq_lock_irq(&rf);
   8201
   8202	schedstat_inc(rq->yld_count);
   8203	current->sched_class->yield_task(rq);
   8204
   8205	preempt_disable();
   8206	rq_unlock_irq(rq, &rf);
   8207	sched_preempt_enable_no_resched();
   8208
   8209	schedule();
   8210}
   8211
   8212/**
   8213 * sys_sched_yield - yield the current processor to other threads.
   8214 *
   8215 * This function yields the current CPU to other tasks. If there are no
   8216 * other threads running on this CPU then this function will return.
   8217 *
   8218 * Return: 0.
   8219 */
   8220SYSCALL_DEFINE0(sched_yield)
   8221{
   8222	do_sched_yield();
   8223	return 0;
   8224}
   8225
   8226#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC)
   8227int __sched __cond_resched(void)
   8228{
   8229	if (should_resched(0)) {
   8230		preempt_schedule_common();
   8231		return 1;
   8232	}
   8233	/*
   8234	 * In preemptible kernels, ->rcu_read_lock_nesting tells the tick
   8235	 * whether the current CPU is in an RCU read-side critical section,
   8236	 * so the tick can report quiescent states even for CPUs looping
   8237	 * in kernel context.  In contrast, in non-preemptible kernels,
   8238	 * RCU readers leave no in-memory hints, which means that CPU-bound
   8239	 * processes executing in kernel context might never report an
   8240	 * RCU quiescent state.  Therefore, the following code causes
   8241	 * cond_resched() to report a quiescent state, but only when RCU
   8242	 * is in urgent need of one.
   8243	 */
   8244#ifndef CONFIG_PREEMPT_RCU
   8245	rcu_all_qs();
   8246#endif
   8247	return 0;
   8248}
   8249EXPORT_SYMBOL(__cond_resched);
   8250#endif
   8251
   8252#ifdef CONFIG_PREEMPT_DYNAMIC
   8253#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
   8254#define cond_resched_dynamic_enabled	__cond_resched
   8255#define cond_resched_dynamic_disabled	((void *)&__static_call_return0)
   8256DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched);
   8257EXPORT_STATIC_CALL_TRAMP(cond_resched);
   8258
   8259#define might_resched_dynamic_enabled	__cond_resched
   8260#define might_resched_dynamic_disabled	((void *)&__static_call_return0)
   8261DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched);
   8262EXPORT_STATIC_CALL_TRAMP(might_resched);
   8263#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
   8264static DEFINE_STATIC_KEY_FALSE(sk_dynamic_cond_resched);
   8265int __sched dynamic_cond_resched(void)
   8266{
   8267	if (!static_branch_unlikely(&sk_dynamic_cond_resched))
   8268		return 0;
   8269	return __cond_resched();
   8270}
   8271EXPORT_SYMBOL(dynamic_cond_resched);
   8272
   8273static DEFINE_STATIC_KEY_FALSE(sk_dynamic_might_resched);
   8274int __sched dynamic_might_resched(void)
   8275{
   8276	if (!static_branch_unlikely(&sk_dynamic_might_resched))
   8277		return 0;
   8278	return __cond_resched();
   8279}
   8280EXPORT_SYMBOL(dynamic_might_resched);
   8281#endif
   8282#endif
   8283
   8284/*
   8285 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
   8286 * call schedule, and on return reacquire the lock.
   8287 *
   8288 * This works OK both with and without CONFIG_PREEMPTION. We do strange low-level
   8289 * operations here to prevent schedule() from being called twice (once via
   8290 * spin_unlock(), once by hand).
   8291 */
   8292int __cond_resched_lock(spinlock_t *lock)
   8293{
   8294	int resched = should_resched(PREEMPT_LOCK_OFFSET);
   8295	int ret = 0;
   8296
   8297	lockdep_assert_held(lock);
   8298
   8299	if (spin_needbreak(lock) || resched) {
   8300		spin_unlock(lock);
   8301		if (!_cond_resched())
   8302			cpu_relax();
   8303		ret = 1;
   8304		spin_lock(lock);
   8305	}
   8306	return ret;
   8307}
   8308EXPORT_SYMBOL(__cond_resched_lock);
   8309
   8310int __cond_resched_rwlock_read(rwlock_t *lock)
   8311{
   8312	int resched = should_resched(PREEMPT_LOCK_OFFSET);
   8313	int ret = 0;
   8314
   8315	lockdep_assert_held_read(lock);
   8316
   8317	if (rwlock_needbreak(lock) || resched) {
   8318		read_unlock(lock);
   8319		if (!_cond_resched())
   8320			cpu_relax();
   8321		ret = 1;
   8322		read_lock(lock);
   8323	}
   8324	return ret;
   8325}
   8326EXPORT_SYMBOL(__cond_resched_rwlock_read);
   8327
   8328int __cond_resched_rwlock_write(rwlock_t *lock)
   8329{
   8330	int resched = should_resched(PREEMPT_LOCK_OFFSET);
   8331	int ret = 0;
   8332
   8333	lockdep_assert_held_write(lock);
   8334
   8335	if (rwlock_needbreak(lock) || resched) {
   8336		write_unlock(lock);
   8337		if (!_cond_resched())
   8338			cpu_relax();
   8339		ret = 1;
   8340		write_lock(lock);
   8341	}
   8342	return ret;
   8343}
   8344EXPORT_SYMBOL(__cond_resched_rwlock_write);
   8345
   8346#ifdef CONFIG_PREEMPT_DYNAMIC
   8347
   8348#ifdef CONFIG_GENERIC_ENTRY
   8349#include <linux/entry-common.h>
   8350#endif
   8351
   8352/*
   8353 * SC:cond_resched
   8354 * SC:might_resched
   8355 * SC:preempt_schedule
   8356 * SC:preempt_schedule_notrace
   8357 * SC:irqentry_exit_cond_resched
   8358 *
   8359 *
   8360 * NONE:
   8361 *   cond_resched               <- __cond_resched
   8362 *   might_resched              <- RET0
   8363 *   preempt_schedule           <- NOP
   8364 *   preempt_schedule_notrace   <- NOP
   8365 *   irqentry_exit_cond_resched <- NOP
   8366 *
   8367 * VOLUNTARY:
   8368 *   cond_resched               <- __cond_resched
   8369 *   might_resched              <- __cond_resched
   8370 *   preempt_schedule           <- NOP
   8371 *   preempt_schedule_notrace   <- NOP
   8372 *   irqentry_exit_cond_resched <- NOP
   8373 *
   8374 * FULL:
   8375 *   cond_resched               <- RET0
   8376 *   might_resched              <- RET0
   8377 *   preempt_schedule           <- preempt_schedule
   8378 *   preempt_schedule_notrace   <- preempt_schedule_notrace
   8379 *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched
   8380 */
   8381
   8382enum {
   8383	preempt_dynamic_undefined = -1,
   8384	preempt_dynamic_none,
   8385	preempt_dynamic_voluntary,
   8386	preempt_dynamic_full,
   8387};
   8388
   8389int preempt_dynamic_mode = preempt_dynamic_undefined;
   8390
   8391int sched_dynamic_mode(const char *str)
   8392{
   8393	if (!strcmp(str, "none"))
   8394		return preempt_dynamic_none;
   8395
   8396	if (!strcmp(str, "voluntary"))
   8397		return preempt_dynamic_voluntary;
   8398
   8399	if (!strcmp(str, "full"))
   8400		return preempt_dynamic_full;
   8401
   8402	return -EINVAL;
   8403}
   8404
   8405#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
   8406#define preempt_dynamic_enable(f)	static_call_update(f, f##_dynamic_enabled)
   8407#define preempt_dynamic_disable(f)	static_call_update(f, f##_dynamic_disabled)
   8408#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
   8409#define preempt_dynamic_enable(f)	static_key_enable(&sk_dynamic_##f.key)
   8410#define preempt_dynamic_disable(f)	static_key_disable(&sk_dynamic_##f.key)
   8411#else
   8412#error "Unsupported PREEMPT_DYNAMIC mechanism"
   8413#endif
   8414
   8415void sched_dynamic_update(int mode)
   8416{
   8417	/*
   8418	 * Avoid {NONE,VOLUNTARY} -> FULL transitions from ever ending up in
   8419	 * the ZERO state, which is invalid.
   8420	 */
   8421	preempt_dynamic_enable(cond_resched);
   8422	preempt_dynamic_enable(might_resched);
   8423	preempt_dynamic_enable(preempt_schedule);
   8424	preempt_dynamic_enable(preempt_schedule_notrace);
   8425	preempt_dynamic_enable(irqentry_exit_cond_resched);
   8426
   8427	switch (mode) {
   8428	case preempt_dynamic_none:
   8429		preempt_dynamic_enable(cond_resched);
   8430		preempt_dynamic_disable(might_resched);
   8431		preempt_dynamic_disable(preempt_schedule);
   8432		preempt_dynamic_disable(preempt_schedule_notrace);
   8433		preempt_dynamic_disable(irqentry_exit_cond_resched);
   8434		pr_info("Dynamic Preempt: none\n");
   8435		break;
   8436
   8437	case preempt_dynamic_voluntary:
   8438		preempt_dynamic_enable(cond_resched);
   8439		preempt_dynamic_enable(might_resched);
   8440		preempt_dynamic_disable(preempt_schedule);
   8441		preempt_dynamic_disable(preempt_schedule_notrace);
   8442		preempt_dynamic_disable(irqentry_exit_cond_resched);
   8443		pr_info("Dynamic Preempt: voluntary\n");
   8444		break;
   8445
   8446	case preempt_dynamic_full:
   8447		preempt_dynamic_disable(cond_resched);
   8448		preempt_dynamic_disable(might_resched);
   8449		preempt_dynamic_enable(preempt_schedule);
   8450		preempt_dynamic_enable(preempt_schedule_notrace);
   8451		preempt_dynamic_enable(irqentry_exit_cond_resched);
   8452		pr_info("Dynamic Preempt: full\n");
   8453		break;
   8454	}
   8455
   8456	preempt_dynamic_mode = mode;
   8457}
   8458
   8459static int __init setup_preempt_mode(char *str)
   8460{
   8461	int mode = sched_dynamic_mode(str);
   8462	if (mode < 0) {
   8463		pr_warn("Dynamic Preempt: unsupported mode: %s\n", str);
   8464		return 0;
   8465	}
   8466
   8467	sched_dynamic_update(mode);
   8468	return 1;
   8469}
   8470__setup("preempt=", setup_preempt_mode);
   8471
   8472static void __init preempt_dynamic_init(void)
   8473{
   8474	if (preempt_dynamic_mode == preempt_dynamic_undefined) {
   8475		if (IS_ENABLED(CONFIG_PREEMPT_NONE)) {
   8476			sched_dynamic_update(preempt_dynamic_none);
   8477		} else if (IS_ENABLED(CONFIG_PREEMPT_VOLUNTARY)) {
   8478			sched_dynamic_update(preempt_dynamic_voluntary);
   8479		} else {
   8480			/* Default static call setting, nothing to do */
   8481			WARN_ON_ONCE(!IS_ENABLED(CONFIG_PREEMPT));
   8482			preempt_dynamic_mode = preempt_dynamic_full;
   8483			pr_info("Dynamic Preempt: full\n");
   8484		}
   8485	}
   8486}
   8487
   8488#define PREEMPT_MODEL_ACCESSOR(mode) \
   8489	bool preempt_model_##mode(void)						 \
   8490	{									 \
   8491		WARN_ON_ONCE(preempt_dynamic_mode == preempt_dynamic_undefined); \
   8492		return preempt_dynamic_mode == preempt_dynamic_##mode;		 \
   8493	}									 \
   8494	EXPORT_SYMBOL_GPL(preempt_model_##mode)
   8495
   8496PREEMPT_MODEL_ACCESSOR(none);
   8497PREEMPT_MODEL_ACCESSOR(voluntary);
   8498PREEMPT_MODEL_ACCESSOR(full);
   8499
   8500#else /* !CONFIG_PREEMPT_DYNAMIC */
   8501
   8502static inline void preempt_dynamic_init(void) { }
   8503
   8504#endif /* #ifdef CONFIG_PREEMPT_DYNAMIC */
   8505
   8506/**
   8507 * yield - yield the current processor to other threads.
   8508 *
   8509 * Do not ever use this function, there's a 99% chance you're doing it wrong.
   8510 *
   8511 * The scheduler is at all times free to pick the calling task as the most
   8512 * eligible task to run, if removing the yield() call from your code breaks
   8513 * it, it's already broken.
   8514 *
   8515 * Typical broken usage is:
   8516 *
   8517 * while (!event)
   8518 *	yield();
   8519 *
   8520 * where one assumes that yield() will let 'the other' process run that will
   8521 * make event true. If the current task is a SCHED_FIFO task that will never
   8522 * happen. Never use yield() as a progress guarantee!!
   8523 *
   8524 * If you want to use yield() to wait for something, use wait_event().
   8525 * If you want to use yield() to be 'nice' for others, use cond_resched().
   8526 * If you still want to use yield(), do not!
   8527 */
   8528void __sched yield(void)
   8529{
   8530	set_current_state(TASK_RUNNING);
   8531	do_sched_yield();
   8532}
   8533EXPORT_SYMBOL(yield);
   8534
   8535/**
   8536 * yield_to - yield the current processor to another thread in
   8537 * your thread group, or accelerate that thread toward the
   8538 * processor it's on.
   8539 * @p: target task
   8540 * @preempt: whether task preemption is allowed or not
   8541 *
   8542 * It's the caller's job to ensure that the target task struct
   8543 * can't go away on us before we can do any checks.
   8544 *
   8545 * Return:
   8546 *	true (>0) if we indeed boosted the target task.
   8547 *	false (0) if we failed to boost the target.
   8548 *	-ESRCH if there's no task to yield to.
   8549 */
   8550int __sched yield_to(struct task_struct *p, bool preempt)
   8551{
   8552	struct task_struct *curr = current;
   8553	struct rq *rq, *p_rq;
   8554	unsigned long flags;
   8555	int yielded = 0;
   8556
   8557	local_irq_save(flags);
   8558	rq = this_rq();
   8559
   8560again:
   8561	p_rq = task_rq(p);
   8562	/*
   8563	 * If we're the only runnable task on the rq and target rq also
   8564	 * has only one task, there's absolutely no point in yielding.
   8565	 */
   8566	if (rq->nr_running == 1 && p_rq->nr_running == 1) {
   8567		yielded = -ESRCH;
   8568		goto out_irq;
   8569	}
   8570
   8571	double_rq_lock(rq, p_rq);
   8572	if (task_rq(p) != p_rq) {
   8573		double_rq_unlock(rq, p_rq);
   8574		goto again;
   8575	}
   8576
   8577	if (!curr->sched_class->yield_to_task)
   8578		goto out_unlock;
   8579
   8580	if (curr->sched_class != p->sched_class)
   8581		goto out_unlock;
   8582
   8583	if (task_running(p_rq, p) || !task_is_running(p))
   8584		goto out_unlock;
   8585
   8586	yielded = curr->sched_class->yield_to_task(rq, p);
   8587	if (yielded) {
   8588		schedstat_inc(rq->yld_count);
   8589		/*
   8590		 * Make p's CPU reschedule; pick_next_entity takes care of
   8591		 * fairness.
   8592		 */
   8593		if (preempt && rq != p_rq)
   8594			resched_curr(p_rq);
   8595	}
   8596
   8597out_unlock:
   8598	double_rq_unlock(rq, p_rq);
   8599out_irq:
   8600	local_irq_restore(flags);
   8601
   8602	if (yielded > 0)
   8603		schedule();
   8604
   8605	return yielded;
   8606}
   8607EXPORT_SYMBOL_GPL(yield_to);
   8608
   8609int io_schedule_prepare(void)
   8610{
   8611	int old_iowait = current->in_iowait;
   8612
   8613	current->in_iowait = 1;
   8614	blk_flush_plug(current->plug, true);
   8615	return old_iowait;
   8616}
   8617
   8618void io_schedule_finish(int token)
   8619{
   8620	current->in_iowait = token;
   8621}
   8622
   8623/*
   8624 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
   8625 * that process accounting knows that this is a task in IO wait state.
   8626 */
   8627long __sched io_schedule_timeout(long timeout)
   8628{
   8629	int token;
   8630	long ret;
   8631
   8632	token = io_schedule_prepare();
   8633	ret = schedule_timeout(timeout);
   8634	io_schedule_finish(token);
   8635
   8636	return ret;
   8637}
   8638EXPORT_SYMBOL(io_schedule_timeout);
   8639
   8640void __sched io_schedule(void)
   8641{
   8642	int token;
   8643
   8644	token = io_schedule_prepare();
   8645	schedule();
   8646	io_schedule_finish(token);
   8647}
   8648EXPORT_SYMBOL(io_schedule);
   8649
   8650/**
   8651 * sys_sched_get_priority_max - return maximum RT priority.
   8652 * @policy: scheduling class.
   8653 *
   8654 * Return: On success, this syscall returns the maximum
   8655 * rt_priority that can be used by a given scheduling class.
   8656 * On failure, a negative error code is returned.
   8657 */
   8658SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
   8659{
   8660	int ret = -EINVAL;
   8661
   8662	switch (policy) {
   8663	case SCHED_FIFO:
   8664	case SCHED_RR:
   8665		ret = MAX_RT_PRIO-1;
   8666		break;
   8667	case SCHED_DEADLINE:
   8668	case SCHED_NORMAL:
   8669	case SCHED_BATCH:
   8670	case SCHED_IDLE:
   8671		ret = 0;
   8672		break;
   8673	}
   8674	return ret;
   8675}
   8676
   8677/**
   8678 * sys_sched_get_priority_min - return minimum RT priority.
   8679 * @policy: scheduling class.
   8680 *
   8681 * Return: On success, this syscall returns the minimum
   8682 * rt_priority that can be used by a given scheduling class.
   8683 * On failure, a negative error code is returned.
   8684 */
   8685SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
   8686{
   8687	int ret = -EINVAL;
   8688
   8689	switch (policy) {
   8690	case SCHED_FIFO:
   8691	case SCHED_RR:
   8692		ret = 1;
   8693		break;
   8694	case SCHED_DEADLINE:
   8695	case SCHED_NORMAL:
   8696	case SCHED_BATCH:
   8697	case SCHED_IDLE:
   8698		ret = 0;
   8699	}
   8700	return ret;
   8701}
   8702
   8703static int sched_rr_get_interval(pid_t pid, struct timespec64 *t)
   8704{
   8705	struct task_struct *p;
   8706	unsigned int time_slice;
   8707	struct rq_flags rf;
   8708	struct rq *rq;
   8709	int retval;
   8710
   8711	if (pid < 0)
   8712		return -EINVAL;
   8713
   8714	retval = -ESRCH;
   8715	rcu_read_lock();
   8716	p = find_process_by_pid(pid);
   8717	if (!p)
   8718		goto out_unlock;
   8719
   8720	retval = security_task_getscheduler(p);
   8721	if (retval)
   8722		goto out_unlock;
   8723
   8724	rq = task_rq_lock(p, &rf);
   8725	time_slice = 0;
   8726	if (p->sched_class->get_rr_interval)
   8727		time_slice = p->sched_class->get_rr_interval(rq, p);
   8728	task_rq_unlock(rq, p, &rf);
   8729
   8730	rcu_read_unlock();
   8731	jiffies_to_timespec64(time_slice, t);
   8732	return 0;
   8733
   8734out_unlock:
   8735	rcu_read_unlock();
   8736	return retval;
   8737}
   8738
   8739/**
   8740 * sys_sched_rr_get_interval - return the default timeslice of a process.
   8741 * @pid: pid of the process.
   8742 * @interval: userspace pointer to the timeslice value.
   8743 *
   8744 * this syscall writes the default timeslice value of a given process
   8745 * into the user-space timespec buffer. A value of '0' means infinity.
   8746 *
   8747 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
   8748 * an error code.
   8749 */
   8750SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
   8751		struct __kernel_timespec __user *, interval)
   8752{
   8753	struct timespec64 t;
   8754	int retval = sched_rr_get_interval(pid, &t);
   8755
   8756	if (retval == 0)
   8757		retval = put_timespec64(&t, interval);
   8758
   8759	return retval;
   8760}
   8761
   8762#ifdef CONFIG_COMPAT_32BIT_TIME
   8763SYSCALL_DEFINE2(sched_rr_get_interval_time32, pid_t, pid,
   8764		struct old_timespec32 __user *, interval)
   8765{
   8766	struct timespec64 t;
   8767	int retval = sched_rr_get_interval(pid, &t);
   8768
   8769	if (retval == 0)
   8770		retval = put_old_timespec32(&t, interval);
   8771	return retval;
   8772}
   8773#endif
   8774
   8775void sched_show_task(struct task_struct *p)
   8776{
   8777	unsigned long free = 0;
   8778	int ppid;
   8779
   8780	if (!try_get_task_stack(p))
   8781		return;
   8782
   8783	pr_info("task:%-15.15s state:%c", p->comm, task_state_to_char(p));
   8784
   8785	if (task_is_running(p))
   8786		pr_cont("  running task    ");
   8787#ifdef CONFIG_DEBUG_STACK_USAGE
   8788	free = stack_not_used(p);
   8789#endif
   8790	ppid = 0;
   8791	rcu_read_lock();
   8792	if (pid_alive(p))
   8793		ppid = task_pid_nr(rcu_dereference(p->real_parent));
   8794	rcu_read_unlock();
   8795	pr_cont(" stack:%5lu pid:%5d ppid:%6d flags:0x%08lx\n",
   8796		free, task_pid_nr(p), ppid,
   8797		read_task_thread_flags(p));
   8798
   8799	print_worker_info(KERN_INFO, p);
   8800	print_stop_info(KERN_INFO, p);
   8801	show_stack(p, NULL, KERN_INFO);
   8802	put_task_stack(p);
   8803}
   8804EXPORT_SYMBOL_GPL(sched_show_task);
   8805
   8806static inline bool
   8807state_filter_match(unsigned long state_filter, struct task_struct *p)
   8808{
   8809	unsigned int state = READ_ONCE(p->__state);
   8810
   8811	/* no filter, everything matches */
   8812	if (!state_filter)
   8813		return true;
   8814
   8815	/* filter, but doesn't match */
   8816	if (!(state & state_filter))
   8817		return false;
   8818
   8819	/*
   8820	 * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows
   8821	 * TASK_KILLABLE).
   8822	 */
   8823	if (state_filter == TASK_UNINTERRUPTIBLE && state == TASK_IDLE)
   8824		return false;
   8825
   8826	return true;
   8827}
   8828
   8829
   8830void show_state_filter(unsigned int state_filter)
   8831{
   8832	struct task_struct *g, *p;
   8833
   8834	rcu_read_lock();
   8835	for_each_process_thread(g, p) {
   8836		/*
   8837		 * reset the NMI-timeout, listing all files on a slow
   8838		 * console might take a lot of time:
   8839		 * Also, reset softlockup watchdogs on all CPUs, because
   8840		 * another CPU might be blocked waiting for us to process
   8841		 * an IPI.
   8842		 */
   8843		touch_nmi_watchdog();
   8844		touch_all_softlockup_watchdogs();
   8845		if (state_filter_match(state_filter, p))
   8846			sched_show_task(p);
   8847	}
   8848
   8849#ifdef CONFIG_SCHED_DEBUG
   8850	if (!state_filter)
   8851		sysrq_sched_debug_show();
   8852#endif
   8853	rcu_read_unlock();
   8854	/*
   8855	 * Only show locks if all tasks are dumped:
   8856	 */
   8857	if (!state_filter)
   8858		debug_show_all_locks();
   8859}
   8860
   8861/**
   8862 * init_idle - set up an idle thread for a given CPU
   8863 * @idle: task in question
   8864 * @cpu: CPU the idle task belongs to
   8865 *
   8866 * NOTE: this function does not set the idle thread's NEED_RESCHED
   8867 * flag, to make booting more robust.
   8868 */
   8869void __init init_idle(struct task_struct *idle, int cpu)
   8870{
   8871	struct rq *rq = cpu_rq(cpu);
   8872	unsigned long flags;
   8873
   8874	__sched_fork(0, idle);
   8875
   8876	raw_spin_lock_irqsave(&idle->pi_lock, flags);
   8877	raw_spin_rq_lock(rq);
   8878
   8879	idle->__state = TASK_RUNNING;
   8880	idle->se.exec_start = sched_clock();
   8881	/*
   8882	 * PF_KTHREAD should already be set at this point; regardless, make it
   8883	 * look like a proper per-CPU kthread.
   8884	 */
   8885	idle->flags |= PF_IDLE | PF_KTHREAD | PF_NO_SETAFFINITY;
   8886	kthread_set_per_cpu(idle, cpu);
   8887
   8888#ifdef CONFIG_SMP
   8889	/*
   8890	 * It's possible that init_idle() gets called multiple times on a task,
   8891	 * in that case do_set_cpus_allowed() will not do the right thing.
   8892	 *
   8893	 * And since this is boot we can forgo the serialization.
   8894	 */
   8895	set_cpus_allowed_common(idle, cpumask_of(cpu), 0);
   8896#endif
   8897	/*
   8898	 * We're having a chicken and egg problem, even though we are
   8899	 * holding rq->lock, the CPU isn't yet set to this CPU so the
   8900	 * lockdep check in task_group() will fail.
   8901	 *
   8902	 * Similar case to sched_fork(). / Alternatively we could
   8903	 * use task_rq_lock() here and obtain the other rq->lock.
   8904	 *
   8905	 * Silence PROVE_RCU
   8906	 */
   8907	rcu_read_lock();
   8908	__set_task_cpu(idle, cpu);
   8909	rcu_read_unlock();
   8910
   8911	rq->idle = idle;
   8912	rcu_assign_pointer(rq->curr, idle);
   8913	idle->on_rq = TASK_ON_RQ_QUEUED;
   8914#ifdef CONFIG_SMP
   8915	idle->on_cpu = 1;
   8916#endif
   8917	raw_spin_rq_unlock(rq);
   8918	raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
   8919
   8920	/* Set the preempt count _outside_ the spinlocks! */
   8921	init_idle_preempt_count(idle, cpu);
   8922
   8923	/*
   8924	 * The idle tasks have their own, simple scheduling class:
   8925	 */
   8926	idle->sched_class = &idle_sched_class;
   8927	ftrace_graph_init_idle_task(idle, cpu);
   8928	vtime_init_idle(idle, cpu);
   8929#ifdef CONFIG_SMP
   8930	sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
   8931#endif
   8932}
   8933
   8934#ifdef CONFIG_SMP
   8935
   8936int cpuset_cpumask_can_shrink(const struct cpumask *cur,
   8937			      const struct cpumask *trial)
   8938{
   8939	int ret = 1;
   8940
   8941	if (cpumask_empty(cur))
   8942		return ret;
   8943
   8944	ret = dl_cpuset_cpumask_can_shrink(cur, trial);
   8945
   8946	return ret;
   8947}
   8948
   8949int task_can_attach(struct task_struct *p,
   8950		    const struct cpumask *cs_cpus_allowed)
   8951{
   8952	int ret = 0;
   8953
   8954	/*
   8955	 * Kthreads which disallow setaffinity shouldn't be moved
   8956	 * to a new cpuset; we don't want to change their CPU
   8957	 * affinity and isolating such threads by their set of
   8958	 * allowed nodes is unnecessary.  Thus, cpusets are not
   8959	 * applicable for such threads.  This prevents checking for
   8960	 * success of set_cpus_allowed_ptr() on all attached tasks
   8961	 * before cpus_mask may be changed.
   8962	 */
   8963	if (p->flags & PF_NO_SETAFFINITY) {
   8964		ret = -EINVAL;
   8965		goto out;
   8966	}
   8967
   8968	if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
   8969					      cs_cpus_allowed)) {
   8970		int cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed);
   8971
   8972		ret = dl_cpu_busy(cpu, p);
   8973	}
   8974
   8975out:
   8976	return ret;
   8977}
   8978
   8979bool sched_smp_initialized __read_mostly;
   8980
   8981#ifdef CONFIG_NUMA_BALANCING
   8982/* Migrate current task p to target_cpu */
   8983int migrate_task_to(struct task_struct *p, int target_cpu)
   8984{
   8985	struct migration_arg arg = { p, target_cpu };
   8986	int curr_cpu = task_cpu(p);
   8987
   8988	if (curr_cpu == target_cpu)
   8989		return 0;
   8990
   8991	if (!cpumask_test_cpu(target_cpu, p->cpus_ptr))
   8992		return -EINVAL;
   8993
   8994	/* TODO: This is not properly updating schedstats */
   8995
   8996	trace_sched_move_numa(p, curr_cpu, target_cpu);
   8997	return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
   8998}
   8999
   9000/*
   9001 * Requeue a task on a given node and accurately track the number of NUMA
   9002 * tasks on the runqueues
   9003 */
   9004void sched_setnuma(struct task_struct *p, int nid)
   9005{
   9006	bool queued, running;
   9007	struct rq_flags rf;
   9008	struct rq *rq;
   9009
   9010	rq = task_rq_lock(p, &rf);
   9011	queued = task_on_rq_queued(p);
   9012	running = task_current(rq, p);
   9013
   9014	if (queued)
   9015		dequeue_task(rq, p, DEQUEUE_SAVE);
   9016	if (running)
   9017		put_prev_task(rq, p);
   9018
   9019	p->numa_preferred_nid = nid;
   9020
   9021	if (queued)
   9022		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
   9023	if (running)
   9024		set_next_task(rq, p);
   9025	task_rq_unlock(rq, p, &rf);
   9026}
   9027#endif /* CONFIG_NUMA_BALANCING */
   9028
   9029#ifdef CONFIG_HOTPLUG_CPU
   9030/*
   9031 * Ensure that the idle task is using init_mm right before its CPU goes
   9032 * offline.
   9033 */
   9034void idle_task_exit(void)
   9035{
   9036	struct mm_struct *mm = current->active_mm;
   9037
   9038	BUG_ON(cpu_online(smp_processor_id()));
   9039	BUG_ON(current != this_rq()->idle);
   9040
   9041	if (mm != &init_mm) {
   9042		switch_mm(mm, &init_mm, current);
   9043		finish_arch_post_lock_switch();
   9044	}
   9045
   9046	/* finish_cpu(), as ran on the BP, will clean up the active_mm state */
   9047}
   9048
   9049static int __balance_push_cpu_stop(void *arg)
   9050{
   9051	struct task_struct *p = arg;
   9052	struct rq *rq = this_rq();
   9053	struct rq_flags rf;
   9054	int cpu;
   9055
   9056	raw_spin_lock_irq(&p->pi_lock);
   9057	rq_lock(rq, &rf);
   9058
   9059	update_rq_clock(rq);
   9060
   9061	if (task_rq(p) == rq && task_on_rq_queued(p)) {
   9062		cpu = select_fallback_rq(rq->cpu, p);
   9063		rq = __migrate_task(rq, &rf, p, cpu);
   9064	}
   9065
   9066	rq_unlock(rq, &rf);
   9067	raw_spin_unlock_irq(&p->pi_lock);
   9068
   9069	put_task_struct(p);
   9070
   9071	return 0;
   9072}
   9073
   9074static DEFINE_PER_CPU(struct cpu_stop_work, push_work);
   9075
   9076/*
   9077 * Ensure we only run per-cpu kthreads once the CPU goes !active.
   9078 *
   9079 * This is enabled below SCHED_AP_ACTIVE; when !cpu_active(), but only
   9080 * effective when the hotplug motion is down.
   9081 */
   9082static void balance_push(struct rq *rq)
   9083{
   9084	struct task_struct *push_task = rq->curr;
   9085
   9086	lockdep_assert_rq_held(rq);
   9087
   9088	/*
   9089	 * Ensure the thing is persistent until balance_push_set(.on = false);
   9090	 */
   9091	rq->balance_callback = &balance_push_callback;
   9092
   9093	/*
   9094	 * Only active while going offline and when invoked on the outgoing
   9095	 * CPU.
   9096	 */
   9097	if (!cpu_dying(rq->cpu) || rq != this_rq())
   9098		return;
   9099
   9100	/*
   9101	 * Both the cpu-hotplug and stop task are in this case and are
   9102	 * required to complete the hotplug process.
   9103	 */
   9104	if (kthread_is_per_cpu(push_task) ||
   9105	    is_migration_disabled(push_task)) {
   9106
   9107		/*
   9108		 * If this is the idle task on the outgoing CPU try to wake
   9109		 * up the hotplug control thread which might wait for the
   9110		 * last task to vanish. The rcuwait_active() check is
   9111		 * accurate here because the waiter is pinned on this CPU
   9112		 * and can't obviously be running in parallel.
   9113		 *
   9114		 * On RT kernels this also has to check whether there are
   9115		 * pinned and scheduled out tasks on the runqueue. They
   9116		 * need to leave the migrate disabled section first.
   9117		 */
   9118		if (!rq->nr_running && !rq_has_pinned_tasks(rq) &&
   9119		    rcuwait_active(&rq->hotplug_wait)) {
   9120			raw_spin_rq_unlock(rq);
   9121			rcuwait_wake_up(&rq->hotplug_wait);
   9122			raw_spin_rq_lock(rq);
   9123		}
   9124		return;
   9125	}
   9126
   9127	get_task_struct(push_task);
   9128	/*
   9129	 * Temporarily drop rq->lock such that we can wake-up the stop task.
   9130	 * Both preemption and IRQs are still disabled.
   9131	 */
   9132	raw_spin_rq_unlock(rq);
   9133	stop_one_cpu_nowait(rq->cpu, __balance_push_cpu_stop, push_task,
   9134			    this_cpu_ptr(&push_work));
   9135	/*
   9136	 * At this point need_resched() is true and we'll take the loop in
   9137	 * schedule(). The next pick is obviously going to be the stop task
   9138	 * which kthread_is_per_cpu() and will push this task away.
   9139	 */
   9140	raw_spin_rq_lock(rq);
   9141}
   9142
   9143static void balance_push_set(int cpu, bool on)
   9144{
   9145	struct rq *rq = cpu_rq(cpu);
   9146	struct rq_flags rf;
   9147
   9148	rq_lock_irqsave(rq, &rf);
   9149	if (on) {
   9150		WARN_ON_ONCE(rq->balance_callback);
   9151		rq->balance_callback = &balance_push_callback;
   9152	} else if (rq->balance_callback == &balance_push_callback) {
   9153		rq->balance_callback = NULL;
   9154	}
   9155	rq_unlock_irqrestore(rq, &rf);
   9156}
   9157
   9158/*
   9159 * Invoked from a CPUs hotplug control thread after the CPU has been marked
   9160 * inactive. All tasks which are not per CPU kernel threads are either
   9161 * pushed off this CPU now via balance_push() or placed on a different CPU
   9162 * during wakeup. Wait until the CPU is quiescent.
   9163 */
   9164static void balance_hotplug_wait(void)
   9165{
   9166	struct rq *rq = this_rq();
   9167
   9168	rcuwait_wait_event(&rq->hotplug_wait,
   9169			   rq->nr_running == 1 && !rq_has_pinned_tasks(rq),
   9170			   TASK_UNINTERRUPTIBLE);
   9171}
   9172
   9173#else
   9174
   9175static inline void balance_push(struct rq *rq)
   9176{
   9177}
   9178
   9179static inline void balance_push_set(int cpu, bool on)
   9180{
   9181}
   9182
   9183static inline void balance_hotplug_wait(void)
   9184{
   9185}
   9186
   9187#endif /* CONFIG_HOTPLUG_CPU */
   9188
   9189void set_rq_online(struct rq *rq)
   9190{
   9191	if (!rq->online) {
   9192		const struct sched_class *class;
   9193
   9194		cpumask_set_cpu(rq->cpu, rq->rd->online);
   9195		rq->online = 1;
   9196
   9197		for_each_class(class) {
   9198			if (class->rq_online)
   9199				class->rq_online(rq);
   9200		}
   9201	}
   9202}
   9203
   9204void set_rq_offline(struct rq *rq)
   9205{
   9206	if (rq->online) {
   9207		const struct sched_class *class;
   9208
   9209		for_each_class(class) {
   9210			if (class->rq_offline)
   9211				class->rq_offline(rq);
   9212		}
   9213
   9214		cpumask_clear_cpu(rq->cpu, rq->rd->online);
   9215		rq->online = 0;
   9216	}
   9217}
   9218
   9219/*
   9220 * used to mark begin/end of suspend/resume:
   9221 */
   9222static int num_cpus_frozen;
   9223
   9224/*
   9225 * Update cpusets according to cpu_active mask.  If cpusets are
   9226 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
   9227 * around partition_sched_domains().
   9228 *
   9229 * If we come here as part of a suspend/resume, don't touch cpusets because we
   9230 * want to restore it back to its original state upon resume anyway.
   9231 */
   9232static void cpuset_cpu_active(void)
   9233{
   9234	if (cpuhp_tasks_frozen) {
   9235		/*
   9236		 * num_cpus_frozen tracks how many CPUs are involved in suspend
   9237		 * resume sequence. As long as this is not the last online
   9238		 * operation in the resume sequence, just build a single sched
   9239		 * domain, ignoring cpusets.
   9240		 */
   9241		partition_sched_domains(1, NULL, NULL);
   9242		if (--num_cpus_frozen)
   9243			return;
   9244		/*
   9245		 * This is the last CPU online operation. So fall through and
   9246		 * restore the original sched domains by considering the
   9247		 * cpuset configurations.
   9248		 */
   9249		cpuset_force_rebuild();
   9250	}
   9251	cpuset_update_active_cpus();
   9252}
   9253
   9254static int cpuset_cpu_inactive(unsigned int cpu)
   9255{
   9256	if (!cpuhp_tasks_frozen) {
   9257		int ret = dl_cpu_busy(cpu, NULL);
   9258
   9259		if (ret)
   9260			return ret;
   9261		cpuset_update_active_cpus();
   9262	} else {
   9263		num_cpus_frozen++;
   9264		partition_sched_domains(1, NULL, NULL);
   9265	}
   9266	return 0;
   9267}
   9268
   9269int sched_cpu_activate(unsigned int cpu)
   9270{
   9271	struct rq *rq = cpu_rq(cpu);
   9272	struct rq_flags rf;
   9273
   9274	/*
   9275	 * Clear the balance_push callback and prepare to schedule
   9276	 * regular tasks.
   9277	 */
   9278	balance_push_set(cpu, false);
   9279
   9280#ifdef CONFIG_SCHED_SMT
   9281	/*
   9282	 * When going up, increment the number of cores with SMT present.
   9283	 */
   9284	if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
   9285		static_branch_inc_cpuslocked(&sched_smt_present);
   9286#endif
   9287	set_cpu_active(cpu, true);
   9288
   9289	if (sched_smp_initialized) {
   9290		sched_update_numa(cpu, true);
   9291		sched_domains_numa_masks_set(cpu);
   9292		cpuset_cpu_active();
   9293	}
   9294
   9295	/*
   9296	 * Put the rq online, if not already. This happens:
   9297	 *
   9298	 * 1) In the early boot process, because we build the real domains
   9299	 *    after all CPUs have been brought up.
   9300	 *
   9301	 * 2) At runtime, if cpuset_cpu_active() fails to rebuild the
   9302	 *    domains.
   9303	 */
   9304	rq_lock_irqsave(rq, &rf);
   9305	if (rq->rd) {
   9306		BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
   9307		set_rq_online(rq);
   9308	}
   9309	rq_unlock_irqrestore(rq, &rf);
   9310
   9311	return 0;
   9312}
   9313
   9314int sched_cpu_deactivate(unsigned int cpu)
   9315{
   9316	struct rq *rq = cpu_rq(cpu);
   9317	struct rq_flags rf;
   9318	int ret;
   9319
   9320	/*
   9321	 * Remove CPU from nohz.idle_cpus_mask to prevent participating in
   9322	 * load balancing when not active
   9323	 */
   9324	nohz_balance_exit_idle(rq);
   9325
   9326	set_cpu_active(cpu, false);
   9327
   9328	/*
   9329	 * From this point forward, this CPU will refuse to run any task that
   9330	 * is not: migrate_disable() or KTHREAD_IS_PER_CPU, and will actively
   9331	 * push those tasks away until this gets cleared, see
   9332	 * sched_cpu_dying().
   9333	 */
   9334	balance_push_set(cpu, true);
   9335
   9336	/*
   9337	 * We've cleared cpu_active_mask / set balance_push, wait for all
   9338	 * preempt-disabled and RCU users of this state to go away such that
   9339	 * all new such users will observe it.
   9340	 *
   9341	 * Specifically, we rely on ttwu to no longer target this CPU, see
   9342	 * ttwu_queue_cond() and is_cpu_allowed().
   9343	 *
   9344	 * Do sync before park smpboot threads to take care the rcu boost case.
   9345	 */
   9346	synchronize_rcu();
   9347
   9348	rq_lock_irqsave(rq, &rf);
   9349	if (rq->rd) {
   9350		update_rq_clock(rq);
   9351		BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
   9352		set_rq_offline(rq);
   9353	}
   9354	rq_unlock_irqrestore(rq, &rf);
   9355
   9356#ifdef CONFIG_SCHED_SMT
   9357	/*
   9358	 * When going down, decrement the number of cores with SMT present.
   9359	 */
   9360	if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
   9361		static_branch_dec_cpuslocked(&sched_smt_present);
   9362
   9363	sched_core_cpu_deactivate(cpu);
   9364#endif
   9365
   9366	if (!sched_smp_initialized)
   9367		return 0;
   9368
   9369	sched_update_numa(cpu, false);
   9370	ret = cpuset_cpu_inactive(cpu);
   9371	if (ret) {
   9372		balance_push_set(cpu, false);
   9373		set_cpu_active(cpu, true);
   9374		sched_update_numa(cpu, true);
   9375		return ret;
   9376	}
   9377	sched_domains_numa_masks_clear(cpu);
   9378	return 0;
   9379}
   9380
   9381static void sched_rq_cpu_starting(unsigned int cpu)
   9382{
   9383	struct rq *rq = cpu_rq(cpu);
   9384
   9385	rq->calc_load_update = calc_load_update;
   9386	update_max_interval();
   9387}
   9388
   9389int sched_cpu_starting(unsigned int cpu)
   9390{
   9391	sched_core_cpu_starting(cpu);
   9392	sched_rq_cpu_starting(cpu);
   9393	sched_tick_start(cpu);
   9394	return 0;
   9395}
   9396
   9397#ifdef CONFIG_HOTPLUG_CPU
   9398
   9399/*
   9400 * Invoked immediately before the stopper thread is invoked to bring the
   9401 * CPU down completely. At this point all per CPU kthreads except the
   9402 * hotplug thread (current) and the stopper thread (inactive) have been
   9403 * either parked or have been unbound from the outgoing CPU. Ensure that
   9404 * any of those which might be on the way out are gone.
   9405 *
   9406 * If after this point a bound task is being woken on this CPU then the
   9407 * responsible hotplug callback has failed to do it's job.
   9408 * sched_cpu_dying() will catch it with the appropriate fireworks.
   9409 */
   9410int sched_cpu_wait_empty(unsigned int cpu)
   9411{
   9412	balance_hotplug_wait();
   9413	return 0;
   9414}
   9415
   9416/*
   9417 * Since this CPU is going 'away' for a while, fold any nr_active delta we
   9418 * might have. Called from the CPU stopper task after ensuring that the
   9419 * stopper is the last running task on the CPU, so nr_active count is
   9420 * stable. We need to take the teardown thread which is calling this into
   9421 * account, so we hand in adjust = 1 to the load calculation.
   9422 *
   9423 * Also see the comment "Global load-average calculations".
   9424 */
   9425static void calc_load_migrate(struct rq *rq)
   9426{
   9427	long delta = calc_load_fold_active(rq, 1);
   9428
   9429	if (delta)
   9430		atomic_long_add(delta, &calc_load_tasks);
   9431}
   9432
   9433static void dump_rq_tasks(struct rq *rq, const char *loglvl)
   9434{
   9435	struct task_struct *g, *p;
   9436	int cpu = cpu_of(rq);
   9437
   9438	lockdep_assert_rq_held(rq);
   9439
   9440	printk("%sCPU%d enqueued tasks (%u total):\n", loglvl, cpu, rq->nr_running);
   9441	for_each_process_thread(g, p) {
   9442		if (task_cpu(p) != cpu)
   9443			continue;
   9444
   9445		if (!task_on_rq_queued(p))
   9446			continue;
   9447
   9448		printk("%s\tpid: %d, name: %s\n", loglvl, p->pid, p->comm);
   9449	}
   9450}
   9451
   9452int sched_cpu_dying(unsigned int cpu)
   9453{
   9454	struct rq *rq = cpu_rq(cpu);
   9455	struct rq_flags rf;
   9456
   9457	/* Handle pending wakeups and then migrate everything off */
   9458	sched_tick_stop(cpu);
   9459
   9460	rq_lock_irqsave(rq, &rf);
   9461	if (rq->nr_running != 1 || rq_has_pinned_tasks(rq)) {
   9462		WARN(true, "Dying CPU not properly vacated!");
   9463		dump_rq_tasks(rq, KERN_WARNING);
   9464	}
   9465	rq_unlock_irqrestore(rq, &rf);
   9466
   9467	calc_load_migrate(rq);
   9468	update_max_interval();
   9469	hrtick_clear(rq);
   9470	sched_core_cpu_dying(cpu);
   9471	return 0;
   9472}
   9473#endif
   9474
   9475void __init sched_init_smp(void)
   9476{
   9477	sched_init_numa(NUMA_NO_NODE);
   9478
   9479	/*
   9480	 * There's no userspace yet to cause hotplug operations; hence all the
   9481	 * CPU masks are stable and all blatant races in the below code cannot
   9482	 * happen.
   9483	 */
   9484	mutex_lock(&sched_domains_mutex);
   9485	sched_init_domains(cpu_active_mask);
   9486	mutex_unlock(&sched_domains_mutex);
   9487
   9488	/* Move init over to a non-isolated CPU */
   9489	if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_TYPE_DOMAIN)) < 0)
   9490		BUG();
   9491	current->flags &= ~PF_NO_SETAFFINITY;
   9492	sched_init_granularity();
   9493
   9494	init_sched_rt_class();
   9495	init_sched_dl_class();
   9496
   9497	sched_smp_initialized = true;
   9498}
   9499
   9500static int __init migration_init(void)
   9501{
   9502	sched_cpu_starting(smp_processor_id());
   9503	return 0;
   9504}
   9505early_initcall(migration_init);
   9506
   9507#else
   9508void __init sched_init_smp(void)
   9509{
   9510	sched_init_granularity();
   9511}
   9512#endif /* CONFIG_SMP */
   9513
   9514int in_sched_functions(unsigned long addr)
   9515{
   9516	return in_lock_functions(addr) ||
   9517		(addr >= (unsigned long)__sched_text_start
   9518		&& addr < (unsigned long)__sched_text_end);
   9519}
   9520
   9521#ifdef CONFIG_CGROUP_SCHED
   9522/*
   9523 * Default task group.
   9524 * Every task in system belongs to this group at bootup.
   9525 */
   9526struct task_group root_task_group;
   9527LIST_HEAD(task_groups);
   9528
   9529/* Cacheline aligned slab cache for task_group */
   9530static struct kmem_cache *task_group_cache __read_mostly;
   9531#endif
   9532
   9533DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
   9534DECLARE_PER_CPU(cpumask_var_t, select_idle_mask);
   9535
   9536void __init sched_init(void)
   9537{
   9538	unsigned long ptr = 0;
   9539	int i;
   9540
   9541	/* Make sure the linker didn't screw up */
   9542	BUG_ON(&idle_sched_class != &fair_sched_class + 1 ||
   9543	       &fair_sched_class != &rt_sched_class + 1 ||
   9544	       &rt_sched_class   != &dl_sched_class + 1);
   9545#ifdef CONFIG_SMP
   9546	BUG_ON(&dl_sched_class != &stop_sched_class + 1);
   9547#endif
   9548
   9549	wait_bit_init();
   9550
   9551#ifdef CONFIG_FAIR_GROUP_SCHED
   9552	ptr += 2 * nr_cpu_ids * sizeof(void **);
   9553#endif
   9554#ifdef CONFIG_RT_GROUP_SCHED
   9555	ptr += 2 * nr_cpu_ids * sizeof(void **);
   9556#endif
   9557	if (ptr) {
   9558		ptr = (unsigned long)kzalloc(ptr, GFP_NOWAIT);
   9559
   9560#ifdef CONFIG_FAIR_GROUP_SCHED
   9561		root_task_group.se = (struct sched_entity **)ptr;
   9562		ptr += nr_cpu_ids * sizeof(void **);
   9563
   9564		root_task_group.cfs_rq = (struct cfs_rq **)ptr;
   9565		ptr += nr_cpu_ids * sizeof(void **);
   9566
   9567		root_task_group.shares = ROOT_TASK_GROUP_LOAD;
   9568		init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
   9569#endif /* CONFIG_FAIR_GROUP_SCHED */
   9570#ifdef CONFIG_RT_GROUP_SCHED
   9571		root_task_group.rt_se = (struct sched_rt_entity **)ptr;
   9572		ptr += nr_cpu_ids * sizeof(void **);
   9573
   9574		root_task_group.rt_rq = (struct rt_rq **)ptr;
   9575		ptr += nr_cpu_ids * sizeof(void **);
   9576
   9577#endif /* CONFIG_RT_GROUP_SCHED */
   9578	}
   9579#ifdef CONFIG_CPUMASK_OFFSTACK
   9580	for_each_possible_cpu(i) {
   9581		per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
   9582			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
   9583		per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node(
   9584			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
   9585	}
   9586#endif /* CONFIG_CPUMASK_OFFSTACK */
   9587
   9588	init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime());
   9589
   9590#ifdef CONFIG_SMP
   9591	init_defrootdomain();
   9592#endif
   9593
   9594#ifdef CONFIG_RT_GROUP_SCHED
   9595	init_rt_bandwidth(&root_task_group.rt_bandwidth,
   9596			global_rt_period(), global_rt_runtime());
   9597#endif /* CONFIG_RT_GROUP_SCHED */
   9598
   9599#ifdef CONFIG_CGROUP_SCHED
   9600	task_group_cache = KMEM_CACHE(task_group, 0);
   9601
   9602	list_add(&root_task_group.list, &task_groups);
   9603	INIT_LIST_HEAD(&root_task_group.children);
   9604	INIT_LIST_HEAD(&root_task_group.siblings);
   9605	autogroup_init(&init_task);
   9606#endif /* CONFIG_CGROUP_SCHED */
   9607
   9608	for_each_possible_cpu(i) {
   9609		struct rq *rq;
   9610
   9611		rq = cpu_rq(i);
   9612		raw_spin_lock_init(&rq->__lock);
   9613		rq->nr_running = 0;
   9614		rq->calc_load_active = 0;
   9615		rq->calc_load_update = jiffies + LOAD_FREQ;
   9616		init_cfs_rq(&rq->cfs);
   9617		init_rt_rq(&rq->rt);
   9618		init_dl_rq(&rq->dl);
   9619#ifdef CONFIG_FAIR_GROUP_SCHED
   9620		INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
   9621		rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
   9622		/*
   9623		 * How much CPU bandwidth does root_task_group get?
   9624		 *
   9625		 * In case of task-groups formed thr' the cgroup filesystem, it
   9626		 * gets 100% of the CPU resources in the system. This overall
   9627		 * system CPU resource is divided among the tasks of
   9628		 * root_task_group and its child task-groups in a fair manner,
   9629		 * based on each entity's (task or task-group's) weight
   9630		 * (se->load.weight).
   9631		 *
   9632		 * In other words, if root_task_group has 10 tasks of weight
   9633		 * 1024) and two child groups A0 and A1 (of weight 1024 each),
   9634		 * then A0's share of the CPU resource is:
   9635		 *
   9636		 *	A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
   9637		 *
   9638		 * We achieve this by letting root_task_group's tasks sit
   9639		 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
   9640		 */
   9641		init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
   9642#endif /* CONFIG_FAIR_GROUP_SCHED */
   9643
   9644		rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
   9645#ifdef CONFIG_RT_GROUP_SCHED
   9646		init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
   9647#endif
   9648#ifdef CONFIG_SMP
   9649		rq->sd = NULL;
   9650		rq->rd = NULL;
   9651		rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
   9652		rq->balance_callback = &balance_push_callback;
   9653		rq->active_balance = 0;
   9654		rq->next_balance = jiffies;
   9655		rq->push_cpu = 0;
   9656		rq->cpu = i;
   9657		rq->online = 0;
   9658		rq->idle_stamp = 0;
   9659		rq->avg_idle = 2*sysctl_sched_migration_cost;
   9660		rq->wake_stamp = jiffies;
   9661		rq->wake_avg_idle = rq->avg_idle;
   9662		rq->max_idle_balance_cost = sysctl_sched_migration_cost;
   9663
   9664		INIT_LIST_HEAD(&rq->cfs_tasks);
   9665
   9666		rq_attach_root(rq, &def_root_domain);
   9667#ifdef CONFIG_NO_HZ_COMMON
   9668		rq->last_blocked_load_update_tick = jiffies;
   9669		atomic_set(&rq->nohz_flags, 0);
   9670
   9671		INIT_CSD(&rq->nohz_csd, nohz_csd_func, rq);
   9672#endif
   9673#ifdef CONFIG_HOTPLUG_CPU
   9674		rcuwait_init(&rq->hotplug_wait);
   9675#endif
   9676#endif /* CONFIG_SMP */
   9677		hrtick_rq_init(rq);
   9678		atomic_set(&rq->nr_iowait, 0);
   9679
   9680#ifdef CONFIG_SCHED_CORE
   9681		rq->core = rq;
   9682		rq->core_pick = NULL;
   9683		rq->core_enabled = 0;
   9684		rq->core_tree = RB_ROOT;
   9685		rq->core_forceidle_count = 0;
   9686		rq->core_forceidle_occupation = 0;
   9687		rq->core_forceidle_start = 0;
   9688
   9689		rq->core_cookie = 0UL;
   9690#endif
   9691	}
   9692
   9693	set_load_weight(&init_task, false);
   9694
   9695	/*
   9696	 * The boot idle thread does lazy MMU switching as well:
   9697	 */
   9698	mmgrab(&init_mm);
   9699	enter_lazy_tlb(&init_mm, current);
   9700
   9701	/*
   9702	 * The idle task doesn't need the kthread struct to function, but it
   9703	 * is dressed up as a per-CPU kthread and thus needs to play the part
   9704	 * if we want to avoid special-casing it in code that deals with per-CPU
   9705	 * kthreads.
   9706	 */
   9707	WARN_ON(!set_kthread_struct(current));
   9708
   9709	/*
   9710	 * Make us the idle thread. Technically, schedule() should not be
   9711	 * called from this thread, however somewhere below it might be,
   9712	 * but because we are the idle thread, we just pick up running again
   9713	 * when this runqueue becomes "idle".
   9714	 */
   9715	init_idle(current, smp_processor_id());
   9716
   9717	calc_load_update = jiffies + LOAD_FREQ;
   9718
   9719#ifdef CONFIG_SMP
   9720	idle_thread_set_boot_cpu();
   9721	balance_push_set(smp_processor_id(), false);
   9722#endif
   9723	init_sched_fair_class();
   9724
   9725	psi_init();
   9726
   9727	init_uclamp();
   9728
   9729	preempt_dynamic_init();
   9730
   9731	scheduler_running = 1;
   9732}
   9733
   9734#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
   9735
   9736void __might_sleep(const char *file, int line)
   9737{
   9738	unsigned int state = get_current_state();
   9739	/*
   9740	 * Blocking primitives will set (and therefore destroy) current->state,
   9741	 * since we will exit with TASK_RUNNING make sure we enter with it,
   9742	 * otherwise we will destroy state.
   9743	 */
   9744	WARN_ONCE(state != TASK_RUNNING && current->task_state_change,
   9745			"do not call blocking ops when !TASK_RUNNING; "
   9746			"state=%x set at [<%p>] %pS\n", state,
   9747			(void *)current->task_state_change,
   9748			(void *)current->task_state_change);
   9749
   9750	__might_resched(file, line, 0);
   9751}
   9752EXPORT_SYMBOL(__might_sleep);
   9753
   9754static void print_preempt_disable_ip(int preempt_offset, unsigned long ip)
   9755{
   9756	if (!IS_ENABLED(CONFIG_DEBUG_PREEMPT))
   9757		return;
   9758
   9759	if (preempt_count() == preempt_offset)
   9760		return;
   9761
   9762	pr_err("Preemption disabled at:");
   9763	print_ip_sym(KERN_ERR, ip);
   9764}
   9765
   9766static inline bool resched_offsets_ok(unsigned int offsets)
   9767{
   9768	unsigned int nested = preempt_count();
   9769
   9770	nested += rcu_preempt_depth() << MIGHT_RESCHED_RCU_SHIFT;
   9771
   9772	return nested == offsets;
   9773}
   9774
   9775void __might_resched(const char *file, int line, unsigned int offsets)
   9776{
   9777	/* Ratelimiting timestamp: */
   9778	static unsigned long prev_jiffy;
   9779
   9780	unsigned long preempt_disable_ip;
   9781
   9782	/* WARN_ON_ONCE() by default, no rate limit required: */
   9783	rcu_sleep_check();
   9784
   9785	if ((resched_offsets_ok(offsets) && !irqs_disabled() &&
   9786	     !is_idle_task(current) && !current->non_block_count) ||
   9787	    system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING ||
   9788	    oops_in_progress)
   9789		return;
   9790
   9791	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
   9792		return;
   9793	prev_jiffy = jiffies;
   9794
   9795	/* Save this before calling printk(), since that will clobber it: */
   9796	preempt_disable_ip = get_preempt_disable_ip(current);
   9797
   9798	pr_err("BUG: sleeping function called from invalid context at %s:%d\n",
   9799	       file, line);
   9800	pr_err("in_atomic(): %d, irqs_disabled(): %d, non_block: %d, pid: %d, name: %s\n",
   9801	       in_atomic(), irqs_disabled(), current->non_block_count,
   9802	       current->pid, current->comm);
   9803	pr_err("preempt_count: %x, expected: %x\n", preempt_count(),
   9804	       offsets & MIGHT_RESCHED_PREEMPT_MASK);
   9805
   9806	if (IS_ENABLED(CONFIG_PREEMPT_RCU)) {
   9807		pr_err("RCU nest depth: %d, expected: %u\n",
   9808		       rcu_preempt_depth(), offsets >> MIGHT_RESCHED_RCU_SHIFT);
   9809	}
   9810
   9811	if (task_stack_end_corrupted(current))
   9812		pr_emerg("Thread overran stack, or stack corrupted\n");
   9813
   9814	debug_show_held_locks(current);
   9815	if (irqs_disabled())
   9816		print_irqtrace_events(current);
   9817
   9818	print_preempt_disable_ip(offsets & MIGHT_RESCHED_PREEMPT_MASK,
   9819				 preempt_disable_ip);
   9820
   9821	dump_stack();
   9822	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
   9823}
   9824EXPORT_SYMBOL(__might_resched);
   9825
   9826void __cant_sleep(const char *file, int line, int preempt_offset)
   9827{
   9828	static unsigned long prev_jiffy;
   9829
   9830	if (irqs_disabled())
   9831		return;
   9832
   9833	if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
   9834		return;
   9835
   9836	if (preempt_count() > preempt_offset)
   9837		return;
   9838
   9839	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
   9840		return;
   9841	prev_jiffy = jiffies;
   9842
   9843	printk(KERN_ERR "BUG: assuming atomic context at %s:%d\n", file, line);
   9844	printk(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
   9845			in_atomic(), irqs_disabled(),
   9846			current->pid, current->comm);
   9847
   9848	debug_show_held_locks(current);
   9849	dump_stack();
   9850	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
   9851}
   9852EXPORT_SYMBOL_GPL(__cant_sleep);
   9853
   9854#ifdef CONFIG_SMP
   9855void __cant_migrate(const char *file, int line)
   9856{
   9857	static unsigned long prev_jiffy;
   9858
   9859	if (irqs_disabled())
   9860		return;
   9861
   9862	if (is_migration_disabled(current))
   9863		return;
   9864
   9865	if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
   9866		return;
   9867
   9868	if (preempt_count() > 0)
   9869		return;
   9870
   9871	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
   9872		return;
   9873	prev_jiffy = jiffies;
   9874
   9875	pr_err("BUG: assuming non migratable context at %s:%d\n", file, line);
   9876	pr_err("in_atomic(): %d, irqs_disabled(): %d, migration_disabled() %u pid: %d, name: %s\n",
   9877	       in_atomic(), irqs_disabled(), is_migration_disabled(current),
   9878	       current->pid, current->comm);
   9879
   9880	debug_show_held_locks(current);
   9881	dump_stack();
   9882	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
   9883}
   9884EXPORT_SYMBOL_GPL(__cant_migrate);
   9885#endif
   9886#endif
   9887
   9888#ifdef CONFIG_MAGIC_SYSRQ
   9889void normalize_rt_tasks(void)
   9890{
   9891	struct task_struct *g, *p;
   9892	struct sched_attr attr = {
   9893		.sched_policy = SCHED_NORMAL,
   9894	};
   9895
   9896	read_lock(&tasklist_lock);
   9897	for_each_process_thread(g, p) {
   9898		/*
   9899		 * Only normalize user tasks:
   9900		 */
   9901		if (p->flags & PF_KTHREAD)
   9902			continue;
   9903
   9904		p->se.exec_start = 0;
   9905		schedstat_set(p->stats.wait_start,  0);
   9906		schedstat_set(p->stats.sleep_start, 0);
   9907		schedstat_set(p->stats.block_start, 0);
   9908
   9909		if (!dl_task(p) && !rt_task(p)) {
   9910			/*
   9911			 * Renice negative nice level userspace
   9912			 * tasks back to 0:
   9913			 */
   9914			if (task_nice(p) < 0)
   9915				set_user_nice(p, 0);
   9916			continue;
   9917		}
   9918
   9919		__sched_setscheduler(p, &attr, false, false);
   9920	}
   9921	read_unlock(&tasklist_lock);
   9922}
   9923
   9924#endif /* CONFIG_MAGIC_SYSRQ */
   9925
   9926#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
   9927/*
   9928 * These functions are only useful for the IA64 MCA handling, or kdb.
   9929 *
   9930 * They can only be called when the whole system has been
   9931 * stopped - every CPU needs to be quiescent, and no scheduling
   9932 * activity can take place. Using them for anything else would
   9933 * be a serious bug, and as a result, they aren't even visible
   9934 * under any other configuration.
   9935 */
   9936
   9937/**
   9938 * curr_task - return the current task for a given CPU.
   9939 * @cpu: the processor in question.
   9940 *
   9941 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
   9942 *
   9943 * Return: The current task for @cpu.
   9944 */
   9945struct task_struct *curr_task(int cpu)
   9946{
   9947	return cpu_curr(cpu);
   9948}
   9949
   9950#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
   9951
   9952#ifdef CONFIG_IA64
   9953/**
   9954 * ia64_set_curr_task - set the current task for a given CPU.
   9955 * @cpu: the processor in question.
   9956 * @p: the task pointer to set.
   9957 *
   9958 * Description: This function must only be used when non-maskable interrupts
   9959 * are serviced on a separate stack. It allows the architecture to switch the
   9960 * notion of the current task on a CPU in a non-blocking manner. This function
   9961 * must be called with all CPU's synchronized, and interrupts disabled, the
   9962 * and caller must save the original value of the current task (see
   9963 * curr_task() above) and restore that value before reenabling interrupts and
   9964 * re-starting the system.
   9965 *
   9966 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
   9967 */
   9968void ia64_set_curr_task(int cpu, struct task_struct *p)
   9969{
   9970	cpu_curr(cpu) = p;
   9971}
   9972
   9973#endif
   9974
   9975#ifdef CONFIG_CGROUP_SCHED
   9976/* task_group_lock serializes the addition/removal of task groups */
   9977static DEFINE_SPINLOCK(task_group_lock);
   9978
   9979static inline void alloc_uclamp_sched_group(struct task_group *tg,
   9980					    struct task_group *parent)
   9981{
   9982#ifdef CONFIG_UCLAMP_TASK_GROUP
   9983	enum uclamp_id clamp_id;
   9984
   9985	for_each_clamp_id(clamp_id) {
   9986		uclamp_se_set(&tg->uclamp_req[clamp_id],
   9987			      uclamp_none(clamp_id), false);
   9988		tg->uclamp[clamp_id] = parent->uclamp[clamp_id];
   9989	}
   9990#endif
   9991}
   9992
   9993static void sched_free_group(struct task_group *tg)
   9994{
   9995	free_fair_sched_group(tg);
   9996	free_rt_sched_group(tg);
   9997	autogroup_free(tg);
   9998	kmem_cache_free(task_group_cache, tg);
   9999}
  10000
  10001static void sched_free_group_rcu(struct rcu_head *rcu)
  10002{
  10003	sched_free_group(container_of(rcu, struct task_group, rcu));
  10004}
  10005
  10006static void sched_unregister_group(struct task_group *tg)
  10007{
  10008	unregister_fair_sched_group(tg);
  10009	unregister_rt_sched_group(tg);
  10010	/*
  10011	 * We have to wait for yet another RCU grace period to expire, as
  10012	 * print_cfs_stats() might run concurrently.
  10013	 */
  10014	call_rcu(&tg->rcu, sched_free_group_rcu);
  10015}
  10016
  10017/* allocate runqueue etc for a new task group */
  10018struct task_group *sched_create_group(struct task_group *parent)
  10019{
  10020	struct task_group *tg;
  10021
  10022	tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
  10023	if (!tg)
  10024		return ERR_PTR(-ENOMEM);
  10025
  10026	if (!alloc_fair_sched_group(tg, parent))
  10027		goto err;
  10028
  10029	if (!alloc_rt_sched_group(tg, parent))
  10030		goto err;
  10031
  10032	alloc_uclamp_sched_group(tg, parent);
  10033
  10034	return tg;
  10035
  10036err:
  10037	sched_free_group(tg);
  10038	return ERR_PTR(-ENOMEM);
  10039}
  10040
  10041void sched_online_group(struct task_group *tg, struct task_group *parent)
  10042{
  10043	unsigned long flags;
  10044
  10045	spin_lock_irqsave(&task_group_lock, flags);
  10046	list_add_rcu(&tg->list, &task_groups);
  10047
  10048	/* Root should already exist: */
  10049	WARN_ON(!parent);
  10050
  10051	tg->parent = parent;
  10052	INIT_LIST_HEAD(&tg->children);
  10053	list_add_rcu(&tg->siblings, &parent->children);
  10054	spin_unlock_irqrestore(&task_group_lock, flags);
  10055
  10056	online_fair_sched_group(tg);
  10057}
  10058
  10059/* rcu callback to free various structures associated with a task group */
  10060static void sched_unregister_group_rcu(struct rcu_head *rhp)
  10061{
  10062	/* Now it should be safe to free those cfs_rqs: */
  10063	sched_unregister_group(container_of(rhp, struct task_group, rcu));
  10064}
  10065
  10066void sched_destroy_group(struct task_group *tg)
  10067{
  10068	/* Wait for possible concurrent references to cfs_rqs complete: */
  10069	call_rcu(&tg->rcu, sched_unregister_group_rcu);
  10070}
  10071
  10072void sched_release_group(struct task_group *tg)
  10073{
  10074	unsigned long flags;
  10075
  10076	/*
  10077	 * Unlink first, to avoid walk_tg_tree_from() from finding us (via
  10078	 * sched_cfs_period_timer()).
  10079	 *
  10080	 * For this to be effective, we have to wait for all pending users of
  10081	 * this task group to leave their RCU critical section to ensure no new
  10082	 * user will see our dying task group any more. Specifically ensure
  10083	 * that tg_unthrottle_up() won't add decayed cfs_rq's to it.
  10084	 *
  10085	 * We therefore defer calling unregister_fair_sched_group() to
  10086	 * sched_unregister_group() which is guarantied to get called only after the
  10087	 * current RCU grace period has expired.
  10088	 */
  10089	spin_lock_irqsave(&task_group_lock, flags);
  10090	list_del_rcu(&tg->list);
  10091	list_del_rcu(&tg->siblings);
  10092	spin_unlock_irqrestore(&task_group_lock, flags);
  10093}
  10094
  10095static void sched_change_group(struct task_struct *tsk, int type)
  10096{
  10097	struct task_group *tg;
  10098
  10099	/*
  10100	 * All callers are synchronized by task_rq_lock(); we do not use RCU
  10101	 * which is pointless here. Thus, we pass "true" to task_css_check()
  10102	 * to prevent lockdep warnings.
  10103	 */
  10104	tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
  10105			  struct task_group, css);
  10106	tg = autogroup_task_group(tsk, tg);
  10107	tsk->sched_task_group = tg;
  10108
  10109#ifdef CONFIG_FAIR_GROUP_SCHED
  10110	if (tsk->sched_class->task_change_group)
  10111		tsk->sched_class->task_change_group(tsk, type);
  10112	else
  10113#endif
  10114		set_task_rq(tsk, task_cpu(tsk));
  10115}
  10116
  10117/*
  10118 * Change task's runqueue when it moves between groups.
  10119 *
  10120 * The caller of this function should have put the task in its new group by
  10121 * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect
  10122 * its new group.
  10123 */
  10124void sched_move_task(struct task_struct *tsk)
  10125{
  10126	int queued, running, queue_flags =
  10127		DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
  10128	struct rq_flags rf;
  10129	struct rq *rq;
  10130
  10131	rq = task_rq_lock(tsk, &rf);
  10132	update_rq_clock(rq);
  10133
  10134	running = task_current(rq, tsk);
  10135	queued = task_on_rq_queued(tsk);
  10136
  10137	if (queued)
  10138		dequeue_task(rq, tsk, queue_flags);
  10139	if (running)
  10140		put_prev_task(rq, tsk);
  10141
  10142	sched_change_group(tsk, TASK_MOVE_GROUP);
  10143
  10144	if (queued)
  10145		enqueue_task(rq, tsk, queue_flags);
  10146	if (running) {
  10147		set_next_task(rq, tsk);
  10148		/*
  10149		 * After changing group, the running task may have joined a
  10150		 * throttled one but it's still the running task. Trigger a
  10151		 * resched to make sure that task can still run.
  10152		 */
  10153		resched_curr(rq);
  10154	}
  10155
  10156	task_rq_unlock(rq, tsk, &rf);
  10157}
  10158
  10159static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
  10160{
  10161	return css ? container_of(css, struct task_group, css) : NULL;
  10162}
  10163
  10164static struct cgroup_subsys_state *
  10165cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
  10166{
  10167	struct task_group *parent = css_tg(parent_css);
  10168	struct task_group *tg;
  10169
  10170	if (!parent) {
  10171		/* This is early initialization for the top cgroup */
  10172		return &root_task_group.css;
  10173	}
  10174
  10175	tg = sched_create_group(parent);
  10176	if (IS_ERR(tg))
  10177		return ERR_PTR(-ENOMEM);
  10178
  10179	return &tg->css;
  10180}
  10181
  10182/* Expose task group only after completing cgroup initialization */
  10183static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
  10184{
  10185	struct task_group *tg = css_tg(css);
  10186	struct task_group *parent = css_tg(css->parent);
  10187
  10188	if (parent)
  10189		sched_online_group(tg, parent);
  10190
  10191#ifdef CONFIG_UCLAMP_TASK_GROUP
  10192	/* Propagate the effective uclamp value for the new group */
  10193	mutex_lock(&uclamp_mutex);
  10194	rcu_read_lock();
  10195	cpu_util_update_eff(css);
  10196	rcu_read_unlock();
  10197	mutex_unlock(&uclamp_mutex);
  10198#endif
  10199
  10200	return 0;
  10201}
  10202
  10203static void cpu_cgroup_css_released(struct cgroup_subsys_state *css)
  10204{
  10205	struct task_group *tg = css_tg(css);
  10206
  10207	sched_release_group(tg);
  10208}
  10209
  10210static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
  10211{
  10212	struct task_group *tg = css_tg(css);
  10213
  10214	/*
  10215	 * Relies on the RCU grace period between css_released() and this.
  10216	 */
  10217	sched_unregister_group(tg);
  10218}
  10219
  10220/*
  10221 * This is called before wake_up_new_task(), therefore we really only
  10222 * have to set its group bits, all the other stuff does not apply.
  10223 */
  10224static void cpu_cgroup_fork(struct task_struct *task)
  10225{
  10226	struct rq_flags rf;
  10227	struct rq *rq;
  10228
  10229	rq = task_rq_lock(task, &rf);
  10230
  10231	update_rq_clock(rq);
  10232	sched_change_group(task, TASK_SET_GROUP);
  10233
  10234	task_rq_unlock(rq, task, &rf);
  10235}
  10236
  10237static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
  10238{
  10239	struct task_struct *task;
  10240	struct cgroup_subsys_state *css;
  10241	int ret = 0;
  10242
  10243	cgroup_taskset_for_each(task, css, tset) {
  10244#ifdef CONFIG_RT_GROUP_SCHED
  10245		if (!sched_rt_can_attach(css_tg(css), task))
  10246			return -EINVAL;
  10247#endif
  10248		/*
  10249		 * Serialize against wake_up_new_task() such that if it's
  10250		 * running, we're sure to observe its full state.
  10251		 */
  10252		raw_spin_lock_irq(&task->pi_lock);
  10253		/*
  10254		 * Avoid calling sched_move_task() before wake_up_new_task()
  10255		 * has happened. This would lead to problems with PELT, due to
  10256		 * move wanting to detach+attach while we're not attached yet.
  10257		 */
  10258		if (READ_ONCE(task->__state) == TASK_NEW)
  10259			ret = -EINVAL;
  10260		raw_spin_unlock_irq(&task->pi_lock);
  10261
  10262		if (ret)
  10263			break;
  10264	}
  10265	return ret;
  10266}
  10267
  10268static void cpu_cgroup_attach(struct cgroup_taskset *tset)
  10269{
  10270	struct task_struct *task;
  10271	struct cgroup_subsys_state *css;
  10272
  10273	cgroup_taskset_for_each(task, css, tset)
  10274		sched_move_task(task);
  10275}
  10276
  10277#ifdef CONFIG_UCLAMP_TASK_GROUP
  10278static void cpu_util_update_eff(struct cgroup_subsys_state *css)
  10279{
  10280	struct cgroup_subsys_state *top_css = css;
  10281	struct uclamp_se *uc_parent = NULL;
  10282	struct uclamp_se *uc_se = NULL;
  10283	unsigned int eff[UCLAMP_CNT];
  10284	enum uclamp_id clamp_id;
  10285	unsigned int clamps;
  10286
  10287	lockdep_assert_held(&uclamp_mutex);
  10288	SCHED_WARN_ON(!rcu_read_lock_held());
  10289
  10290	css_for_each_descendant_pre(css, top_css) {
  10291		uc_parent = css_tg(css)->parent
  10292			? css_tg(css)->parent->uclamp : NULL;
  10293
  10294		for_each_clamp_id(clamp_id) {
  10295			/* Assume effective clamps matches requested clamps */
  10296			eff[clamp_id] = css_tg(css)->uclamp_req[clamp_id].value;
  10297			/* Cap effective clamps with parent's effective clamps */
  10298			if (uc_parent &&
  10299			    eff[clamp_id] > uc_parent[clamp_id].value) {
  10300				eff[clamp_id] = uc_parent[clamp_id].value;
  10301			}
  10302		}
  10303		/* Ensure protection is always capped by limit */
  10304		eff[UCLAMP_MIN] = min(eff[UCLAMP_MIN], eff[UCLAMP_MAX]);
  10305
  10306		/* Propagate most restrictive effective clamps */
  10307		clamps = 0x0;
  10308		uc_se = css_tg(css)->uclamp;
  10309		for_each_clamp_id(clamp_id) {
  10310			if (eff[clamp_id] == uc_se[clamp_id].value)
  10311				continue;
  10312			uc_se[clamp_id].value = eff[clamp_id];
  10313			uc_se[clamp_id].bucket_id = uclamp_bucket_id(eff[clamp_id]);
  10314			clamps |= (0x1 << clamp_id);
  10315		}
  10316		if (!clamps) {
  10317			css = css_rightmost_descendant(css);
  10318			continue;
  10319		}
  10320
  10321		/* Immediately update descendants RUNNABLE tasks */
  10322		uclamp_update_active_tasks(css);
  10323	}
  10324}
  10325
  10326/*
  10327 * Integer 10^N with a given N exponent by casting to integer the literal "1eN"
  10328 * C expression. Since there is no way to convert a macro argument (N) into a
  10329 * character constant, use two levels of macros.
  10330 */
  10331#define _POW10(exp) ((unsigned int)1e##exp)
  10332#define POW10(exp) _POW10(exp)
  10333
  10334struct uclamp_request {
  10335#define UCLAMP_PERCENT_SHIFT	2
  10336#define UCLAMP_PERCENT_SCALE	(100 * POW10(UCLAMP_PERCENT_SHIFT))
  10337	s64 percent;
  10338	u64 util;
  10339	int ret;
  10340};
  10341
  10342static inline struct uclamp_request
  10343capacity_from_percent(char *buf)
  10344{
  10345	struct uclamp_request req = {
  10346		.percent = UCLAMP_PERCENT_SCALE,
  10347		.util = SCHED_CAPACITY_SCALE,
  10348		.ret = 0,
  10349	};
  10350
  10351	buf = strim(buf);
  10352	if (strcmp(buf, "max")) {
  10353		req.ret = cgroup_parse_float(buf, UCLAMP_PERCENT_SHIFT,
  10354					     &req.percent);
  10355		if (req.ret)
  10356			return req;
  10357		if ((u64)req.percent > UCLAMP_PERCENT_SCALE) {
  10358			req.ret = -ERANGE;
  10359			return req;
  10360		}
  10361
  10362		req.util = req.percent << SCHED_CAPACITY_SHIFT;
  10363		req.util = DIV_ROUND_CLOSEST_ULL(req.util, UCLAMP_PERCENT_SCALE);
  10364	}
  10365
  10366	return req;
  10367}
  10368
  10369static ssize_t cpu_uclamp_write(struct kernfs_open_file *of, char *buf,
  10370				size_t nbytes, loff_t off,
  10371				enum uclamp_id clamp_id)
  10372{
  10373	struct uclamp_request req;
  10374	struct task_group *tg;
  10375
  10376	req = capacity_from_percent(buf);
  10377	if (req.ret)
  10378		return req.ret;
  10379
  10380	static_branch_enable(&sched_uclamp_used);
  10381
  10382	mutex_lock(&uclamp_mutex);
  10383	rcu_read_lock();
  10384
  10385	tg = css_tg(of_css(of));
  10386	if (tg->uclamp_req[clamp_id].value != req.util)
  10387		uclamp_se_set(&tg->uclamp_req[clamp_id], req.util, false);
  10388
  10389	/*
  10390	 * Because of not recoverable conversion rounding we keep track of the
  10391	 * exact requested value
  10392	 */
  10393	tg->uclamp_pct[clamp_id] = req.percent;
  10394
  10395	/* Update effective clamps to track the most restrictive value */
  10396	cpu_util_update_eff(of_css(of));
  10397
  10398	rcu_read_unlock();
  10399	mutex_unlock(&uclamp_mutex);
  10400
  10401	return nbytes;
  10402}
  10403
  10404static ssize_t cpu_uclamp_min_write(struct kernfs_open_file *of,
  10405				    char *buf, size_t nbytes,
  10406				    loff_t off)
  10407{
  10408	return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MIN);
  10409}
  10410
  10411static ssize_t cpu_uclamp_max_write(struct kernfs_open_file *of,
  10412				    char *buf, size_t nbytes,
  10413				    loff_t off)
  10414{
  10415	return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MAX);
  10416}
  10417
  10418static inline void cpu_uclamp_print(struct seq_file *sf,
  10419				    enum uclamp_id clamp_id)
  10420{
  10421	struct task_group *tg;
  10422	u64 util_clamp;
  10423	u64 percent;
  10424	u32 rem;
  10425
  10426	rcu_read_lock();
  10427	tg = css_tg(seq_css(sf));
  10428	util_clamp = tg->uclamp_req[clamp_id].value;
  10429	rcu_read_unlock();
  10430
  10431	if (util_clamp == SCHED_CAPACITY_SCALE) {
  10432		seq_puts(sf, "max\n");
  10433		return;
  10434	}
  10435
  10436	percent = tg->uclamp_pct[clamp_id];
  10437	percent = div_u64_rem(percent, POW10(UCLAMP_PERCENT_SHIFT), &rem);
  10438	seq_printf(sf, "%llu.%0*u\n", percent, UCLAMP_PERCENT_SHIFT, rem);
  10439}
  10440
  10441static int cpu_uclamp_min_show(struct seq_file *sf, void *v)
  10442{
  10443	cpu_uclamp_print(sf, UCLAMP_MIN);
  10444	return 0;
  10445}
  10446
  10447static int cpu_uclamp_max_show(struct seq_file *sf, void *v)
  10448{
  10449	cpu_uclamp_print(sf, UCLAMP_MAX);
  10450	return 0;
  10451}
  10452#endif /* CONFIG_UCLAMP_TASK_GROUP */
  10453
  10454#ifdef CONFIG_FAIR_GROUP_SCHED
  10455static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
  10456				struct cftype *cftype, u64 shareval)
  10457{
  10458	if (shareval > scale_load_down(ULONG_MAX))
  10459		shareval = MAX_SHARES;
  10460	return sched_group_set_shares(css_tg(css), scale_load(shareval));
  10461}
  10462
  10463static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
  10464			       struct cftype *cft)
  10465{
  10466	struct task_group *tg = css_tg(css);
  10467
  10468	return (u64) scale_load_down(tg->shares);
  10469}
  10470
  10471#ifdef CONFIG_CFS_BANDWIDTH
  10472static DEFINE_MUTEX(cfs_constraints_mutex);
  10473
  10474const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
  10475static const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
  10476/* More than 203 days if BW_SHIFT equals 20. */
  10477static const u64 max_cfs_runtime = MAX_BW * NSEC_PER_USEC;
  10478
  10479static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
  10480
  10481static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota,
  10482				u64 burst)
  10483{
  10484	int i, ret = 0, runtime_enabled, runtime_was_enabled;
  10485	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
  10486
  10487	if (tg == &root_task_group)
  10488		return -EINVAL;
  10489
  10490	/*
  10491	 * Ensure we have at some amount of bandwidth every period.  This is
  10492	 * to prevent reaching a state of large arrears when throttled via
  10493	 * entity_tick() resulting in prolonged exit starvation.
  10494	 */
  10495	if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
  10496		return -EINVAL;
  10497
  10498	/*
  10499	 * Likewise, bound things on the other side by preventing insane quota
  10500	 * periods.  This also allows us to normalize in computing quota
  10501	 * feasibility.
  10502	 */
  10503	if (period > max_cfs_quota_period)
  10504		return -EINVAL;
  10505
  10506	/*
  10507	 * Bound quota to defend quota against overflow during bandwidth shift.
  10508	 */
  10509	if (quota != RUNTIME_INF && quota > max_cfs_runtime)
  10510		return -EINVAL;
  10511
  10512	if (quota != RUNTIME_INF && (burst > quota ||
  10513				     burst + quota > max_cfs_runtime))
  10514		return -EINVAL;
  10515
  10516	/*
  10517	 * Prevent race between setting of cfs_rq->runtime_enabled and
  10518	 * unthrottle_offline_cfs_rqs().
  10519	 */
  10520	cpus_read_lock();
  10521	mutex_lock(&cfs_constraints_mutex);
  10522	ret = __cfs_schedulable(tg, period, quota);
  10523	if (ret)
  10524		goto out_unlock;
  10525
  10526	runtime_enabled = quota != RUNTIME_INF;
  10527	runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
  10528	/*
  10529	 * If we need to toggle cfs_bandwidth_used, off->on must occur
  10530	 * before making related changes, and on->off must occur afterwards
  10531	 */
  10532	if (runtime_enabled && !runtime_was_enabled)
  10533		cfs_bandwidth_usage_inc();
  10534	raw_spin_lock_irq(&cfs_b->lock);
  10535	cfs_b->period = ns_to_ktime(period);
  10536	cfs_b->quota = quota;
  10537	cfs_b->burst = burst;
  10538
  10539	__refill_cfs_bandwidth_runtime(cfs_b);
  10540
  10541	/* Restart the period timer (if active) to handle new period expiry: */
  10542	if (runtime_enabled)
  10543		start_cfs_bandwidth(cfs_b);
  10544
  10545	raw_spin_unlock_irq(&cfs_b->lock);
  10546
  10547	for_each_online_cpu(i) {
  10548		struct cfs_rq *cfs_rq = tg->cfs_rq[i];
  10549		struct rq *rq = cfs_rq->rq;
  10550		struct rq_flags rf;
  10551
  10552		rq_lock_irq(rq, &rf);
  10553		cfs_rq->runtime_enabled = runtime_enabled;
  10554		cfs_rq->runtime_remaining = 0;
  10555
  10556		if (cfs_rq->throttled)
  10557			unthrottle_cfs_rq(cfs_rq);
  10558		rq_unlock_irq(rq, &rf);
  10559	}
  10560	if (runtime_was_enabled && !runtime_enabled)
  10561		cfs_bandwidth_usage_dec();
  10562out_unlock:
  10563	mutex_unlock(&cfs_constraints_mutex);
  10564	cpus_read_unlock();
  10565
  10566	return ret;
  10567}
  10568
  10569static int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
  10570{
  10571	u64 quota, period, burst;
  10572
  10573	period = ktime_to_ns(tg->cfs_bandwidth.period);
  10574	burst = tg->cfs_bandwidth.burst;
  10575	if (cfs_quota_us < 0)
  10576		quota = RUNTIME_INF;
  10577	else if ((u64)cfs_quota_us <= U64_MAX / NSEC_PER_USEC)
  10578		quota = (u64)cfs_quota_us * NSEC_PER_USEC;
  10579	else
  10580		return -EINVAL;
  10581
  10582	return tg_set_cfs_bandwidth(tg, period, quota, burst);
  10583}
  10584
  10585static long tg_get_cfs_quota(struct task_group *tg)
  10586{
  10587	u64 quota_us;
  10588
  10589	if (tg->cfs_bandwidth.quota == RUNTIME_INF)
  10590		return -1;
  10591
  10592	quota_us = tg->cfs_bandwidth.quota;
  10593	do_div(quota_us, NSEC_PER_USEC);
  10594
  10595	return quota_us;
  10596}
  10597
  10598static int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
  10599{
  10600	u64 quota, period, burst;
  10601
  10602	if ((u64)cfs_period_us > U64_MAX / NSEC_PER_USEC)
  10603		return -EINVAL;
  10604
  10605	period = (u64)cfs_period_us * NSEC_PER_USEC;
  10606	quota = tg->cfs_bandwidth.quota;
  10607	burst = tg->cfs_bandwidth.burst;
  10608
  10609	return tg_set_cfs_bandwidth(tg, period, quota, burst);
  10610}
  10611
  10612static long tg_get_cfs_period(struct task_group *tg)
  10613{
  10614	u64 cfs_period_us;
  10615
  10616	cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
  10617	do_div(cfs_period_us, NSEC_PER_USEC);
  10618
  10619	return cfs_period_us;
  10620}
  10621
  10622static int tg_set_cfs_burst(struct task_group *tg, long cfs_burst_us)
  10623{
  10624	u64 quota, period, burst;
  10625
  10626	if ((u64)cfs_burst_us > U64_MAX / NSEC_PER_USEC)
  10627		return -EINVAL;
  10628
  10629	burst = (u64)cfs_burst_us * NSEC_PER_USEC;
  10630	period = ktime_to_ns(tg->cfs_bandwidth.period);
  10631	quota = tg->cfs_bandwidth.quota;
  10632
  10633	return tg_set_cfs_bandwidth(tg, period, quota, burst);
  10634}
  10635
  10636static long tg_get_cfs_burst(struct task_group *tg)
  10637{
  10638	u64 burst_us;
  10639
  10640	burst_us = tg->cfs_bandwidth.burst;
  10641	do_div(burst_us, NSEC_PER_USEC);
  10642
  10643	return burst_us;
  10644}
  10645
  10646static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
  10647				  struct cftype *cft)
  10648{
  10649	return tg_get_cfs_quota(css_tg(css));
  10650}
  10651
  10652static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
  10653				   struct cftype *cftype, s64 cfs_quota_us)
  10654{
  10655	return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
  10656}
  10657
  10658static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
  10659				   struct cftype *cft)
  10660{
  10661	return tg_get_cfs_period(css_tg(css));
  10662}
  10663
  10664static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
  10665				    struct cftype *cftype, u64 cfs_period_us)
  10666{
  10667	return tg_set_cfs_period(css_tg(css), cfs_period_us);
  10668}
  10669
  10670static u64 cpu_cfs_burst_read_u64(struct cgroup_subsys_state *css,
  10671				  struct cftype *cft)
  10672{
  10673	return tg_get_cfs_burst(css_tg(css));
  10674}
  10675
  10676static int cpu_cfs_burst_write_u64(struct cgroup_subsys_state *css,
  10677				   struct cftype *cftype, u64 cfs_burst_us)
  10678{
  10679	return tg_set_cfs_burst(css_tg(css), cfs_burst_us);
  10680}
  10681
  10682struct cfs_schedulable_data {
  10683	struct task_group *tg;
  10684	u64 period, quota;
  10685};
  10686
  10687/*
  10688 * normalize group quota/period to be quota/max_period
  10689 * note: units are usecs
  10690 */
  10691static u64 normalize_cfs_quota(struct task_group *tg,
  10692			       struct cfs_schedulable_data *d)
  10693{
  10694	u64 quota, period;
  10695
  10696	if (tg == d->tg) {
  10697		period = d->period;
  10698		quota = d->quota;
  10699	} else {
  10700		period = tg_get_cfs_period(tg);
  10701		quota = tg_get_cfs_quota(tg);
  10702	}
  10703
  10704	/* note: these should typically be equivalent */
  10705	if (quota == RUNTIME_INF || quota == -1)
  10706		return RUNTIME_INF;
  10707
  10708	return to_ratio(period, quota);
  10709}
  10710
  10711static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
  10712{
  10713	struct cfs_schedulable_data *d = data;
  10714	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
  10715	s64 quota = 0, parent_quota = -1;
  10716
  10717	if (!tg->parent) {
  10718		quota = RUNTIME_INF;
  10719	} else {
  10720		struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
  10721
  10722		quota = normalize_cfs_quota(tg, d);
  10723		parent_quota = parent_b->hierarchical_quota;
  10724
  10725		/*
  10726		 * Ensure max(child_quota) <= parent_quota.  On cgroup2,
  10727		 * always take the min.  On cgroup1, only inherit when no
  10728		 * limit is set:
  10729		 */
  10730		if (cgroup_subsys_on_dfl(cpu_cgrp_subsys)) {
  10731			quota = min(quota, parent_quota);
  10732		} else {
  10733			if (quota == RUNTIME_INF)
  10734				quota = parent_quota;
  10735			else if (parent_quota != RUNTIME_INF && quota > parent_quota)
  10736				return -EINVAL;
  10737		}
  10738	}
  10739	cfs_b->hierarchical_quota = quota;
  10740
  10741	return 0;
  10742}
  10743
  10744static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
  10745{
  10746	int ret;
  10747	struct cfs_schedulable_data data = {
  10748		.tg = tg,
  10749		.period = period,
  10750		.quota = quota,
  10751	};
  10752
  10753	if (quota != RUNTIME_INF) {
  10754		do_div(data.period, NSEC_PER_USEC);
  10755		do_div(data.quota, NSEC_PER_USEC);
  10756	}
  10757
  10758	rcu_read_lock();
  10759	ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
  10760	rcu_read_unlock();
  10761
  10762	return ret;
  10763}
  10764
  10765static int cpu_cfs_stat_show(struct seq_file *sf, void *v)
  10766{
  10767	struct task_group *tg = css_tg(seq_css(sf));
  10768	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
  10769
  10770	seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
  10771	seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
  10772	seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
  10773
  10774	if (schedstat_enabled() && tg != &root_task_group) {
  10775		struct sched_statistics *stats;
  10776		u64 ws = 0;
  10777		int i;
  10778
  10779		for_each_possible_cpu(i) {
  10780			stats = __schedstats_from_se(tg->se[i]);
  10781			ws += schedstat_val(stats->wait_sum);
  10782		}
  10783
  10784		seq_printf(sf, "wait_sum %llu\n", ws);
  10785	}
  10786
  10787	seq_printf(sf, "nr_bursts %d\n", cfs_b->nr_burst);
  10788	seq_printf(sf, "burst_time %llu\n", cfs_b->burst_time);
  10789
  10790	return 0;
  10791}
  10792#endif /* CONFIG_CFS_BANDWIDTH */
  10793#endif /* CONFIG_FAIR_GROUP_SCHED */
  10794
  10795#ifdef CONFIG_RT_GROUP_SCHED
  10796static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
  10797				struct cftype *cft, s64 val)
  10798{
  10799	return sched_group_set_rt_runtime(css_tg(css), val);
  10800}
  10801
  10802static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
  10803			       struct cftype *cft)
  10804{
  10805	return sched_group_rt_runtime(css_tg(css));
  10806}
  10807
  10808static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
  10809				    struct cftype *cftype, u64 rt_period_us)
  10810{
  10811	return sched_group_set_rt_period(css_tg(css), rt_period_us);
  10812}
  10813
  10814static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
  10815				   struct cftype *cft)
  10816{
  10817	return sched_group_rt_period(css_tg(css));
  10818}
  10819#endif /* CONFIG_RT_GROUP_SCHED */
  10820
  10821#ifdef CONFIG_FAIR_GROUP_SCHED
  10822static s64 cpu_idle_read_s64(struct cgroup_subsys_state *css,
  10823			       struct cftype *cft)
  10824{
  10825	return css_tg(css)->idle;
  10826}
  10827
  10828static int cpu_idle_write_s64(struct cgroup_subsys_state *css,
  10829				struct cftype *cft, s64 idle)
  10830{
  10831	return sched_group_set_idle(css_tg(css), idle);
  10832}
  10833#endif
  10834
  10835static struct cftype cpu_legacy_files[] = {
  10836#ifdef CONFIG_FAIR_GROUP_SCHED
  10837	{
  10838		.name = "shares",
  10839		.read_u64 = cpu_shares_read_u64,
  10840		.write_u64 = cpu_shares_write_u64,
  10841	},
  10842	{
  10843		.name = "idle",
  10844		.read_s64 = cpu_idle_read_s64,
  10845		.write_s64 = cpu_idle_write_s64,
  10846	},
  10847#endif
  10848#ifdef CONFIG_CFS_BANDWIDTH
  10849	{
  10850		.name = "cfs_quota_us",
  10851		.read_s64 = cpu_cfs_quota_read_s64,
  10852		.write_s64 = cpu_cfs_quota_write_s64,
  10853	},
  10854	{
  10855		.name = "cfs_period_us",
  10856		.read_u64 = cpu_cfs_period_read_u64,
  10857		.write_u64 = cpu_cfs_period_write_u64,
  10858	},
  10859	{
  10860		.name = "cfs_burst_us",
  10861		.read_u64 = cpu_cfs_burst_read_u64,
  10862		.write_u64 = cpu_cfs_burst_write_u64,
  10863	},
  10864	{
  10865		.name = "stat",
  10866		.seq_show = cpu_cfs_stat_show,
  10867	},
  10868#endif
  10869#ifdef CONFIG_RT_GROUP_SCHED
  10870	{
  10871		.name = "rt_runtime_us",
  10872		.read_s64 = cpu_rt_runtime_read,
  10873		.write_s64 = cpu_rt_runtime_write,
  10874	},
  10875	{
  10876		.name = "rt_period_us",
  10877		.read_u64 = cpu_rt_period_read_uint,
  10878		.write_u64 = cpu_rt_period_write_uint,
  10879	},
  10880#endif
  10881#ifdef CONFIG_UCLAMP_TASK_GROUP
  10882	{
  10883		.name = "uclamp.min",
  10884		.flags = CFTYPE_NOT_ON_ROOT,
  10885		.seq_show = cpu_uclamp_min_show,
  10886		.write = cpu_uclamp_min_write,
  10887	},
  10888	{
  10889		.name = "uclamp.max",
  10890		.flags = CFTYPE_NOT_ON_ROOT,
  10891		.seq_show = cpu_uclamp_max_show,
  10892		.write = cpu_uclamp_max_write,
  10893	},
  10894#endif
  10895	{ }	/* Terminate */
  10896};
  10897
  10898static int cpu_extra_stat_show(struct seq_file *sf,
  10899			       struct cgroup_subsys_state *css)
  10900{
  10901#ifdef CONFIG_CFS_BANDWIDTH
  10902	{
  10903		struct task_group *tg = css_tg(css);
  10904		struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
  10905		u64 throttled_usec, burst_usec;
  10906
  10907		throttled_usec = cfs_b->throttled_time;
  10908		do_div(throttled_usec, NSEC_PER_USEC);
  10909		burst_usec = cfs_b->burst_time;
  10910		do_div(burst_usec, NSEC_PER_USEC);
  10911
  10912		seq_printf(sf, "nr_periods %d\n"
  10913			   "nr_throttled %d\n"
  10914			   "throttled_usec %llu\n"
  10915			   "nr_bursts %d\n"
  10916			   "burst_usec %llu\n",
  10917			   cfs_b->nr_periods, cfs_b->nr_throttled,
  10918			   throttled_usec, cfs_b->nr_burst, burst_usec);
  10919	}
  10920#endif
  10921	return 0;
  10922}
  10923
  10924#ifdef CONFIG_FAIR_GROUP_SCHED
  10925static u64 cpu_weight_read_u64(struct cgroup_subsys_state *css,
  10926			       struct cftype *cft)
  10927{
  10928	struct task_group *tg = css_tg(css);
  10929	u64 weight = scale_load_down(tg->shares);
  10930
  10931	return DIV_ROUND_CLOSEST_ULL(weight * CGROUP_WEIGHT_DFL, 1024);
  10932}
  10933
  10934static int cpu_weight_write_u64(struct cgroup_subsys_state *css,
  10935				struct cftype *cft, u64 weight)
  10936{
  10937	/*
  10938	 * cgroup weight knobs should use the common MIN, DFL and MAX
  10939	 * values which are 1, 100 and 10000 respectively.  While it loses
  10940	 * a bit of range on both ends, it maps pretty well onto the shares
  10941	 * value used by scheduler and the round-trip conversions preserve
  10942	 * the original value over the entire range.
  10943	 */
  10944	if (weight < CGROUP_WEIGHT_MIN || weight > CGROUP_WEIGHT_MAX)
  10945		return -ERANGE;
  10946
  10947	weight = DIV_ROUND_CLOSEST_ULL(weight * 1024, CGROUP_WEIGHT_DFL);
  10948
  10949	return sched_group_set_shares(css_tg(css), scale_load(weight));
  10950}
  10951
  10952static s64 cpu_weight_nice_read_s64(struct cgroup_subsys_state *css,
  10953				    struct cftype *cft)
  10954{
  10955	unsigned long weight = scale_load_down(css_tg(css)->shares);
  10956	int last_delta = INT_MAX;
  10957	int prio, delta;
  10958
  10959	/* find the closest nice value to the current weight */
  10960	for (prio = 0; prio < ARRAY_SIZE(sched_prio_to_weight); prio++) {
  10961		delta = abs(sched_prio_to_weight[prio] - weight);
  10962		if (delta >= last_delta)
  10963			break;
  10964		last_delta = delta;
  10965	}
  10966
  10967	return PRIO_TO_NICE(prio - 1 + MAX_RT_PRIO);
  10968}
  10969
  10970static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css,
  10971				     struct cftype *cft, s64 nice)
  10972{
  10973	unsigned long weight;
  10974	int idx;
  10975
  10976	if (nice < MIN_NICE || nice > MAX_NICE)
  10977		return -ERANGE;
  10978
  10979	idx = NICE_TO_PRIO(nice) - MAX_RT_PRIO;
  10980	idx = array_index_nospec(idx, 40);
  10981	weight = sched_prio_to_weight[idx];
  10982
  10983	return sched_group_set_shares(css_tg(css), scale_load(weight));
  10984}
  10985#endif
  10986
  10987static void __maybe_unused cpu_period_quota_print(struct seq_file *sf,
  10988						  long period, long quota)
  10989{
  10990	if (quota < 0)
  10991		seq_puts(sf, "max");
  10992	else
  10993		seq_printf(sf, "%ld", quota);
  10994
  10995	seq_printf(sf, " %ld\n", period);
  10996}
  10997
  10998/* caller should put the current value in *@periodp before calling */
  10999static int __maybe_unused cpu_period_quota_parse(char *buf,
  11000						 u64 *periodp, u64 *quotap)
  11001{
  11002	char tok[21];	/* U64_MAX */
  11003
  11004	if (sscanf(buf, "%20s %llu", tok, periodp) < 1)
  11005		return -EINVAL;
  11006
  11007	*periodp *= NSEC_PER_USEC;
  11008
  11009	if (sscanf(tok, "%llu", quotap))
  11010		*quotap *= NSEC_PER_USEC;
  11011	else if (!strcmp(tok, "max"))
  11012		*quotap = RUNTIME_INF;
  11013	else
  11014		return -EINVAL;
  11015
  11016	return 0;
  11017}
  11018
  11019#ifdef CONFIG_CFS_BANDWIDTH
  11020static int cpu_max_show(struct seq_file *sf, void *v)
  11021{
  11022	struct task_group *tg = css_tg(seq_css(sf));
  11023
  11024	cpu_period_quota_print(sf, tg_get_cfs_period(tg), tg_get_cfs_quota(tg));
  11025	return 0;
  11026}
  11027
  11028static ssize_t cpu_max_write(struct kernfs_open_file *of,
  11029			     char *buf, size_t nbytes, loff_t off)
  11030{
  11031	struct task_group *tg = css_tg(of_css(of));
  11032	u64 period = tg_get_cfs_period(tg);
  11033	u64 burst = tg_get_cfs_burst(tg);
  11034	u64 quota;
  11035	int ret;
  11036
  11037	ret = cpu_period_quota_parse(buf, &period, &quota);
  11038	if (!ret)
  11039		ret = tg_set_cfs_bandwidth(tg, period, quota, burst);
  11040	return ret ?: nbytes;
  11041}
  11042#endif
  11043
  11044static struct cftype cpu_files[] = {
  11045#ifdef CONFIG_FAIR_GROUP_SCHED
  11046	{
  11047		.name = "weight",
  11048		.flags = CFTYPE_NOT_ON_ROOT,
  11049		.read_u64 = cpu_weight_read_u64,
  11050		.write_u64 = cpu_weight_write_u64,
  11051	},
  11052	{
  11053		.name = "weight.nice",
  11054		.flags = CFTYPE_NOT_ON_ROOT,
  11055		.read_s64 = cpu_weight_nice_read_s64,
  11056		.write_s64 = cpu_weight_nice_write_s64,
  11057	},
  11058	{
  11059		.name = "idle",
  11060		.flags = CFTYPE_NOT_ON_ROOT,
  11061		.read_s64 = cpu_idle_read_s64,
  11062		.write_s64 = cpu_idle_write_s64,
  11063	},
  11064#endif
  11065#ifdef CONFIG_CFS_BANDWIDTH
  11066	{
  11067		.name = "max",
  11068		.flags = CFTYPE_NOT_ON_ROOT,
  11069		.seq_show = cpu_max_show,
  11070		.write = cpu_max_write,
  11071	},
  11072	{
  11073		.name = "max.burst",
  11074		.flags = CFTYPE_NOT_ON_ROOT,
  11075		.read_u64 = cpu_cfs_burst_read_u64,
  11076		.write_u64 = cpu_cfs_burst_write_u64,
  11077	},
  11078#endif
  11079#ifdef CONFIG_UCLAMP_TASK_GROUP
  11080	{
  11081		.name = "uclamp.min",
  11082		.flags = CFTYPE_NOT_ON_ROOT,
  11083		.seq_show = cpu_uclamp_min_show,
  11084		.write = cpu_uclamp_min_write,
  11085	},
  11086	{
  11087		.name = "uclamp.max",
  11088		.flags = CFTYPE_NOT_ON_ROOT,
  11089		.seq_show = cpu_uclamp_max_show,
  11090		.write = cpu_uclamp_max_write,
  11091	},
  11092#endif
  11093	{ }	/* terminate */
  11094};
  11095
  11096struct cgroup_subsys cpu_cgrp_subsys = {
  11097	.css_alloc	= cpu_cgroup_css_alloc,
  11098	.css_online	= cpu_cgroup_css_online,
  11099	.css_released	= cpu_cgroup_css_released,
  11100	.css_free	= cpu_cgroup_css_free,
  11101	.css_extra_stat_show = cpu_extra_stat_show,
  11102	.fork		= cpu_cgroup_fork,
  11103	.can_attach	= cpu_cgroup_can_attach,
  11104	.attach		= cpu_cgroup_attach,
  11105	.legacy_cftypes	= cpu_legacy_files,
  11106	.dfl_cftypes	= cpu_files,
  11107	.early_init	= true,
  11108	.threaded	= true,
  11109};
  11110
  11111#endif	/* CONFIG_CGROUP_SCHED */
  11112
  11113void dump_cpu_task(int cpu)
  11114{
  11115	pr_info("Task dump for CPU %d:\n", cpu);
  11116	sched_show_task(cpu_curr(cpu));
  11117}
  11118
  11119/*
  11120 * Nice levels are multiplicative, with a gentle 10% change for every
  11121 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
  11122 * nice 1, it will get ~10% less CPU time than another CPU-bound task
  11123 * that remained on nice 0.
  11124 *
  11125 * The "10% effect" is relative and cumulative: from _any_ nice level,
  11126 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
  11127 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
  11128 * If a task goes up by ~10% and another task goes down by ~10% then
  11129 * the relative distance between them is ~25%.)
  11130 */
  11131const int sched_prio_to_weight[40] = {
  11132 /* -20 */     88761,     71755,     56483,     46273,     36291,
  11133 /* -15 */     29154,     23254,     18705,     14949,     11916,
  11134 /* -10 */      9548,      7620,      6100,      4904,      3906,
  11135 /*  -5 */      3121,      2501,      1991,      1586,      1277,
  11136 /*   0 */      1024,       820,       655,       526,       423,
  11137 /*   5 */       335,       272,       215,       172,       137,
  11138 /*  10 */       110,        87,        70,        56,        45,
  11139 /*  15 */        36,        29,        23,        18,        15,
  11140};
  11141
  11142/*
  11143 * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
  11144 *
  11145 * In cases where the weight does not change often, we can use the
  11146 * precalculated inverse to speed up arithmetics by turning divisions
  11147 * into multiplications:
  11148 */
  11149const u32 sched_prio_to_wmult[40] = {
  11150 /* -20 */     48388,     59856,     76040,     92818,    118348,
  11151 /* -15 */    147320,    184698,    229616,    287308,    360437,
  11152 /* -10 */    449829,    563644,    704093,    875809,   1099582,
  11153 /*  -5 */   1376151,   1717300,   2157191,   2708050,   3363326,
  11154 /*   0 */   4194304,   5237765,   6557202,   8165337,  10153587,
  11155 /*   5 */  12820798,  15790321,  19976592,  24970740,  31350126,
  11156 /*  10 */  39045157,  49367440,  61356676,  76695844,  95443717,
  11157 /*  15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
  11158};
  11159
  11160void call_trace_sched_update_nr_running(struct rq *rq, int count)
  11161{
  11162        trace_sched_update_nr_running_tp(rq, count);
  11163}