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((¶virt_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, ¶m); 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(¬ifier->link, ¤t->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(¬ifier->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, "a); 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}