From 8dce7a9a6f4ca7163161a80a4603b66c88c5de8e Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Thu, 13 Jun 2013 18:41:16 -0400 Subject: lockdep: Be nice about building from userspace Lockdep is an awesome piece of code which detects locking issues which are relevant both to userspace and kernelspace. We can easily make lockdep work in userspace since there is really no kernel spacific magic going on in the code. All we need is to wrap two functions which are used by lockdep and are very kernel specific. Doing that will allow tools located in tools/ to easily utilize lockdep's code for their own use. Signed-off-by: Sasha Levin Signed-off-by: Peter Zijlstra Cc: penberg@kernel.org Cc: torvalds@linux-foundation.org Link: http://lkml.kernel.org/r/1352753446-24109-1-git-send-email-sasha.levin@oracle.com Signed-off-by: Ingo Molnar --- kernel/locking/lockdep.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel/locking') diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 576ba756a32d..eb8a54783fa0 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -590,6 +590,7 @@ static int very_verbose(struct lock_class *class) /* * Is this the address of a static object: */ +#ifdef __KERNEL__ static int static_obj(void *obj) { unsigned long start = (unsigned long) &_stext, @@ -616,6 +617,7 @@ static int static_obj(void *obj) */ return is_module_address(addr) || is_module_percpu_address(addr); } +#endif /* * To make lock name printouts unique, we calculate a unique @@ -4115,6 +4117,7 @@ void debug_check_no_locks_held(void) } EXPORT_SYMBOL_GPL(debug_check_no_locks_held); +#ifdef __KERNEL__ void debug_show_all_locks(void) { struct task_struct *g, *p; @@ -4172,6 +4175,7 @@ retry: read_unlock(&tasklist_lock); } EXPORT_SYMBOL_GPL(debug_show_all_locks); +#endif /* * Careful: only use this function if you are sure that -- cgit v1.2.3-71-gd317 From 91f30a17024ff0d8345e11228af33ee938b13426 Mon Sep 17 00:00:00 2001 From: Chuansheng Liu Date: Wed, 4 Dec 2013 13:58:13 +0800 Subject: mutexes: Give more informative mutex warning in the !lock->owner case When mutex debugging is enabled and an imbalanced mutex_unlock() is called, we get the following, slightly confusing warning: [ 364.208284] DEBUG_LOCKS_WARN_ON(lock->owner != current) But in that case the warning is due to an imbalanced mutex_unlock() call, and the lock->owner is NULL - so the message is misleading. So improve the message by testing for this case specifically: DEBUG_LOCKS_WARN_ON(!lock->owner) Signed-off-by: Liu, Chuansheng Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Cc: Andrew Morton Cc: Thomas Gleixner Cc: Paul E. McKenney Link: http://lkml.kernel.org/r/1386136693.3650.48.camel@cliu38-desktop-build [ Improved the changelog, changed the patch to use !lock->owner consistently. ] Signed-off-by: Ingo Molnar --- kernel/locking/mutex-debug.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'kernel/locking') diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c index 7e3443fe1f48..faf6f5b53e77 100644 --- a/kernel/locking/mutex-debug.c +++ b/kernel/locking/mutex-debug.c @@ -75,7 +75,12 @@ void debug_mutex_unlock(struct mutex *lock) return; DEBUG_LOCKS_WARN_ON(lock->magic != lock); - DEBUG_LOCKS_WARN_ON(lock->owner != current); + + if (!lock->owner) + DEBUG_LOCKS_WARN_ON(!lock->owner); + else + DEBUG_LOCKS_WARN_ON(lock->owner != current); + DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next); mutex_clear_owner(lock); } -- cgit v1.2.3-71-gd317 From fb00aca474405f4fa8a8519c3179fed722eabd83 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 7 Nov 2013 14:43:43 +0100 Subject: rtmutex: Turn the plist into an rb-tree Turn the pi-chains from plist to rb-tree, in the rt_mutex code, and provide a proper comparison function for -deadline and -priority tasks. This is done mainly because: - classical prio field of the plist is just an int, which might not be enough for representing a deadline; - manipulating such a list would become O(nr_deadline_tasks), which might be to much, as the number of -deadline task increases. Therefore, an rb-tree is used, and tasks are queued in it according to the following logic: - among two -priority (i.e., SCHED_BATCH/OTHER/RR/FIFO) tasks, the one with the higher (lower, actually!) prio wins; - among a -priority and a -deadline task, the latter always wins; - among two -deadline tasks, the one with the earliest deadline wins. Queueing and dequeueing functions are changed accordingly, for both the list of a task's pi-waiters and the list of tasks blocked on a pi-lock. Signed-off-by: Peter Zijlstra Signed-off-by: Dario Faggioli Signed-off-by: Juri Lelli Signed-off-again-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1383831828-15501-10-git-send-email-juri.lelli@gmail.com Signed-off-by: Ingo Molnar --- include/linux/init_task.h | 10 +++ include/linux/rtmutex.h | 18 ++--- include/linux/sched.h | 4 +- kernel/fork.c | 3 +- kernel/futex.c | 2 + kernel/locking/rtmutex-debug.c | 8 +-- kernel/locking/rtmutex.c | 151 ++++++++++++++++++++++++++++++++-------- kernel/locking/rtmutex_common.h | 22 +++--- kernel/sched/core.c | 4 -- 9 files changed, 157 insertions(+), 65 deletions(-) (limited to 'kernel/locking') diff --git a/include/linux/init_task.h b/include/linux/init_task.h index b0ed422e4e4a..f0e52383a001 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -11,6 +11,7 @@ #include #include #include +#include #include #include @@ -154,6 +155,14 @@ extern struct task_group root_task_group; #define INIT_TASK_COMM "swapper" +#ifdef CONFIG_RT_MUTEXES +# define INIT_RT_MUTEXES(tsk) \ + .pi_waiters = RB_ROOT, \ + .pi_waiters_leftmost = NULL, +#else +# define INIT_RT_MUTEXES(tsk) +#endif + /* * INIT_TASK is used to set up the first task table, touch at * your own risk!. Base=0, limit=0x1fffff (=2MB) @@ -221,6 +230,7 @@ extern struct task_group root_task_group; INIT_TRACE_RECURSION \ INIT_TASK_RCU_PREEMPT(tsk) \ INIT_CPUSET_SEQ(tsk) \ + INIT_RT_MUTEXES(tsk) \ INIT_VTIME(tsk) \ } diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h index de17134244f3..3aed8d737e1a 100644 --- a/include/linux/rtmutex.h +++ b/include/linux/rtmutex.h @@ -13,7 +13,7 @@ #define __LINUX_RT_MUTEX_H #include -#include +#include #include extern int max_lock_depth; /* for sysctl */ @@ -22,12 +22,14 @@ extern int max_lock_depth; /* for sysctl */ * The rt_mutex structure * * @wait_lock: spinlock to protect the structure - * @wait_list: pilist head to enqueue waiters in priority order + * @waiters: rbtree root to enqueue waiters in priority order + * @waiters_leftmost: top waiter * @owner: the mutex owner */ struct rt_mutex { raw_spinlock_t wait_lock; - struct plist_head wait_list; + struct rb_root waiters; + struct rb_node *waiters_leftmost; struct task_struct *owner; #ifdef CONFIG_DEBUG_RT_MUTEXES int save_state; @@ -66,7 +68,7 @@ struct hrtimer_sleeper; #define __RT_MUTEX_INITIALIZER(mutexname) \ { .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \ - , .wait_list = PLIST_HEAD_INIT(mutexname.wait_list) \ + , .waiters = RB_ROOT \ , .owner = NULL \ __DEBUG_RT_MUTEX_INITIALIZER(mutexname)} @@ -98,12 +100,4 @@ extern int rt_mutex_trylock(struct rt_mutex *lock); extern void rt_mutex_unlock(struct rt_mutex *lock); -#ifdef CONFIG_RT_MUTEXES -# define INIT_RT_MUTEXES(tsk) \ - .pi_waiters = PLIST_HEAD_INIT(tsk.pi_waiters), \ - INIT_RT_MUTEX_DEBUG(tsk) -#else -# define INIT_RT_MUTEXES(tsk) -#endif - #endif diff --git a/include/linux/sched.h b/include/linux/sched.h index 158f4c2dd852..9ea15019a5b6 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -16,6 +16,7 @@ struct sched_param { #include #include #include +#include #include #include #include @@ -1354,7 +1355,8 @@ struct task_struct { #ifdef CONFIG_RT_MUTEXES /* PI waiters blocked on a rt_mutex held by this task */ - struct plist_head pi_waiters; + struct rb_root pi_waiters; + struct rb_node *pi_waiters_leftmost; /* Deadlock detection and priority inheritance handling */ struct rt_mutex_waiter *pi_blocked_on; #endif diff --git a/kernel/fork.c b/kernel/fork.c index e6c0f1a22914..7049ae526a54 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1087,7 +1087,8 @@ static void rt_mutex_init_task(struct task_struct *p) { raw_spin_lock_init(&p->pi_lock); #ifdef CONFIG_RT_MUTEXES - plist_head_init(&p->pi_waiters); + p->pi_waiters = RB_ROOT; + p->pi_waiters_leftmost = NULL; p->pi_blocked_on = NULL; #endif } diff --git a/kernel/futex.c b/kernel/futex.c index f6ff0191ecf7..679531c61d96 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -2316,6 +2316,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, * code while we sleep on uaddr. */ debug_rt_mutex_init_waiter(&rt_waiter); + RB_CLEAR_NODE(&rt_waiter.pi_tree_entry); + RB_CLEAR_NODE(&rt_waiter.tree_entry); rt_waiter.task = NULL; ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE); diff --git a/kernel/locking/rtmutex-debug.c b/kernel/locking/rtmutex-debug.c index 13b243a323fa..49b2ed3dced8 100644 --- a/kernel/locking/rtmutex-debug.c +++ b/kernel/locking/rtmutex-debug.c @@ -24,7 +24,7 @@ #include #include #include -#include +#include #include #include @@ -57,7 +57,7 @@ static void printk_lock(struct rt_mutex *lock, int print_owner) void rt_mutex_debug_task_free(struct task_struct *task) { - DEBUG_LOCKS_WARN_ON(!plist_head_empty(&task->pi_waiters)); + DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters)); DEBUG_LOCKS_WARN_ON(task->pi_blocked_on); } @@ -154,16 +154,12 @@ void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock) void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter) { memset(waiter, 0x11, sizeof(*waiter)); - plist_node_init(&waiter->list_entry, MAX_PRIO); - plist_node_init(&waiter->pi_list_entry, MAX_PRIO); waiter->deadlock_task_pid = NULL; } void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter) { put_pid(waiter->deadlock_task_pid); - DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->list_entry)); - DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->pi_list_entry)); memset(waiter, 0x22, sizeof(*waiter)); } diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 0dd6aec1cb6a..3bf0aa68dd3f 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include "rtmutex_common.h" @@ -91,10 +92,104 @@ static inline void mark_rt_mutex_waiters(struct rt_mutex *lock) } #endif +static inline int +rt_mutex_waiter_less(struct rt_mutex_waiter *left, + struct rt_mutex_waiter *right) +{ + if (left->task->prio < right->task->prio) + return 1; + + /* + * If both tasks are dl_task(), we check their deadlines. + */ + if (dl_prio(left->task->prio) && dl_prio(right->task->prio)) + return (left->task->dl.deadline < right->task->dl.deadline); + + return 0; +} + +static void +rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter) +{ + struct rb_node **link = &lock->waiters.rb_node; + struct rb_node *parent = NULL; + struct rt_mutex_waiter *entry; + int leftmost = 1; + + while (*link) { + parent = *link; + entry = rb_entry(parent, struct rt_mutex_waiter, tree_entry); + if (rt_mutex_waiter_less(waiter, entry)) { + link = &parent->rb_left; + } else { + link = &parent->rb_right; + leftmost = 0; + } + } + + if (leftmost) + lock->waiters_leftmost = &waiter->tree_entry; + + rb_link_node(&waiter->tree_entry, parent, link); + rb_insert_color(&waiter->tree_entry, &lock->waiters); +} + +static void +rt_mutex_dequeue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter) +{ + if (RB_EMPTY_NODE(&waiter->tree_entry)) + return; + + if (lock->waiters_leftmost == &waiter->tree_entry) + lock->waiters_leftmost = rb_next(&waiter->tree_entry); + + rb_erase(&waiter->tree_entry, &lock->waiters); + RB_CLEAR_NODE(&waiter->tree_entry); +} + +static void +rt_mutex_enqueue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter) +{ + struct rb_node **link = &task->pi_waiters.rb_node; + struct rb_node *parent = NULL; + struct rt_mutex_waiter *entry; + int leftmost = 1; + + while (*link) { + parent = *link; + entry = rb_entry(parent, struct rt_mutex_waiter, pi_tree_entry); + if (rt_mutex_waiter_less(waiter, entry)) { + link = &parent->rb_left; + } else { + link = &parent->rb_right; + leftmost = 0; + } + } + + if (leftmost) + task->pi_waiters_leftmost = &waiter->pi_tree_entry; + + rb_link_node(&waiter->pi_tree_entry, parent, link); + rb_insert_color(&waiter->pi_tree_entry, &task->pi_waiters); +} + +static void +rt_mutex_dequeue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter) +{ + if (RB_EMPTY_NODE(&waiter->pi_tree_entry)) + return; + + if (task->pi_waiters_leftmost == &waiter->pi_tree_entry) + task->pi_waiters_leftmost = rb_next(&waiter->pi_tree_entry); + + rb_erase(&waiter->pi_tree_entry, &task->pi_waiters); + RB_CLEAR_NODE(&waiter->pi_tree_entry); +} + /* - * Calculate task priority from the waiter list priority + * Calculate task priority from the waiter tree priority * - * Return task->normal_prio when the waiter list is empty or when + * Return task->normal_prio when the waiter tree is empty or when * the waiter is not allowed to do priority boosting */ int rt_mutex_getprio(struct task_struct *task) @@ -102,7 +197,7 @@ int rt_mutex_getprio(struct task_struct *task) if (likely(!task_has_pi_waiters(task))) return task->normal_prio; - return min(task_top_pi_waiter(task)->pi_list_entry.prio, + return min(task_top_pi_waiter(task)->task->prio, task->normal_prio); } @@ -233,7 +328,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task, * When deadlock detection is off then we check, if further * priority adjustment is necessary. */ - if (!detect_deadlock && waiter->list_entry.prio == task->prio) + if (!detect_deadlock && waiter->task->prio == task->prio) goto out_unlock_pi; lock = waiter->lock; @@ -254,9 +349,9 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task, top_waiter = rt_mutex_top_waiter(lock); /* Requeue the waiter */ - plist_del(&waiter->list_entry, &lock->wait_list); - waiter->list_entry.prio = task->prio; - plist_add(&waiter->list_entry, &lock->wait_list); + rt_mutex_dequeue(lock, waiter); + waiter->task->prio = task->prio; + rt_mutex_enqueue(lock, waiter); /* Release the task */ raw_spin_unlock_irqrestore(&task->pi_lock, flags); @@ -280,17 +375,15 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task, if (waiter == rt_mutex_top_waiter(lock)) { /* Boost the owner */ - plist_del(&top_waiter->pi_list_entry, &task->pi_waiters); - waiter->pi_list_entry.prio = waiter->list_entry.prio; - plist_add(&waiter->pi_list_entry, &task->pi_waiters); + rt_mutex_dequeue_pi(task, top_waiter); + rt_mutex_enqueue_pi(task, waiter); __rt_mutex_adjust_prio(task); } else if (top_waiter == waiter) { /* Deboost the owner */ - plist_del(&waiter->pi_list_entry, &task->pi_waiters); + rt_mutex_dequeue_pi(task, waiter); waiter = rt_mutex_top_waiter(lock); - waiter->pi_list_entry.prio = waiter->list_entry.prio; - plist_add(&waiter->pi_list_entry, &task->pi_waiters); + rt_mutex_enqueue_pi(task, waiter); __rt_mutex_adjust_prio(task); } @@ -355,7 +448,7 @@ static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task, * 3) it is top waiter */ if (rt_mutex_has_waiters(lock)) { - if (task->prio >= rt_mutex_top_waiter(lock)->list_entry.prio) { + if (task->prio >= rt_mutex_top_waiter(lock)->task->prio) { if (!waiter || waiter != rt_mutex_top_waiter(lock)) return 0; } @@ -369,7 +462,7 @@ static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task, /* remove the queued waiter. */ if (waiter) { - plist_del(&waiter->list_entry, &lock->wait_list); + rt_mutex_dequeue(lock, waiter); task->pi_blocked_on = NULL; } @@ -379,8 +472,7 @@ static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task, */ if (rt_mutex_has_waiters(lock)) { top = rt_mutex_top_waiter(lock); - top->pi_list_entry.prio = top->list_entry.prio; - plist_add(&top->pi_list_entry, &task->pi_waiters); + rt_mutex_enqueue_pi(task, top); } raw_spin_unlock_irqrestore(&task->pi_lock, flags); } @@ -416,13 +508,11 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock, __rt_mutex_adjust_prio(task); waiter->task = task; waiter->lock = lock; - plist_node_init(&waiter->list_entry, task->prio); - plist_node_init(&waiter->pi_list_entry, task->prio); /* Get the top priority waiter on the lock */ if (rt_mutex_has_waiters(lock)) top_waiter = rt_mutex_top_waiter(lock); - plist_add(&waiter->list_entry, &lock->wait_list); + rt_mutex_enqueue(lock, waiter); task->pi_blocked_on = waiter; @@ -433,8 +523,8 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock, if (waiter == rt_mutex_top_waiter(lock)) { raw_spin_lock_irqsave(&owner->pi_lock, flags); - plist_del(&top_waiter->pi_list_entry, &owner->pi_waiters); - plist_add(&waiter->pi_list_entry, &owner->pi_waiters); + rt_mutex_dequeue_pi(owner, top_waiter); + rt_mutex_enqueue_pi(owner, waiter); __rt_mutex_adjust_prio(owner); if (owner->pi_blocked_on) @@ -486,7 +576,7 @@ static void wakeup_next_waiter(struct rt_mutex *lock) * boosted mode and go back to normal after releasing * lock->wait_lock. */ - plist_del(&waiter->pi_list_entry, ¤t->pi_waiters); + rt_mutex_dequeue_pi(current, waiter); rt_mutex_set_owner(lock, NULL); @@ -510,7 +600,7 @@ static void remove_waiter(struct rt_mutex *lock, int chain_walk = 0; raw_spin_lock_irqsave(¤t->pi_lock, flags); - plist_del(&waiter->list_entry, &lock->wait_list); + rt_mutex_dequeue(lock, waiter); current->pi_blocked_on = NULL; raw_spin_unlock_irqrestore(¤t->pi_lock, flags); @@ -521,13 +611,13 @@ static void remove_waiter(struct rt_mutex *lock, raw_spin_lock_irqsave(&owner->pi_lock, flags); - plist_del(&waiter->pi_list_entry, &owner->pi_waiters); + rt_mutex_dequeue_pi(owner, waiter); if (rt_mutex_has_waiters(lock)) { struct rt_mutex_waiter *next; next = rt_mutex_top_waiter(lock); - plist_add(&next->pi_list_entry, &owner->pi_waiters); + rt_mutex_enqueue_pi(owner, next); } __rt_mutex_adjust_prio(owner); @@ -537,8 +627,6 @@ static void remove_waiter(struct rt_mutex *lock, raw_spin_unlock_irqrestore(&owner->pi_lock, flags); } - WARN_ON(!plist_node_empty(&waiter->pi_list_entry)); - if (!chain_walk) return; @@ -565,7 +653,7 @@ void rt_mutex_adjust_pi(struct task_struct *task) raw_spin_lock_irqsave(&task->pi_lock, flags); waiter = task->pi_blocked_on; - if (!waiter || waiter->list_entry.prio == task->prio) { + if (!waiter || waiter->task->prio == task->prio) { raw_spin_unlock_irqrestore(&task->pi_lock, flags); return; } @@ -638,6 +726,8 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state, int ret = 0; debug_rt_mutex_init_waiter(&waiter); + RB_CLEAR_NODE(&waiter.pi_tree_entry); + RB_CLEAR_NODE(&waiter.tree_entry); raw_spin_lock(&lock->wait_lock); @@ -904,7 +994,8 @@ void __rt_mutex_init(struct rt_mutex *lock, const char *name) { lock->owner = NULL; raw_spin_lock_init(&lock->wait_lock); - plist_head_init(&lock->wait_list); + lock->waiters = RB_ROOT; + lock->waiters_leftmost = NULL; debug_rt_mutex_init(lock, name); } diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h index 53a66c85261b..b65442fe5ade 100644 --- a/kernel/locking/rtmutex_common.h +++ b/kernel/locking/rtmutex_common.h @@ -40,13 +40,13 @@ extern void schedule_rt_mutex_test(struct rt_mutex *lock); * This is the control structure for tasks blocked on a rt_mutex, * which is allocated on the kernel stack on of the blocked task. * - * @list_entry: pi node to enqueue into the mutex waiters list - * @pi_list_entry: pi node to enqueue into the mutex owner waiters list + * @tree_entry: pi node to enqueue into the mutex waiters tree + * @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree * @task: task reference to the blocked task */ struct rt_mutex_waiter { - struct plist_node list_entry; - struct plist_node pi_list_entry; + struct rb_node tree_entry; + struct rb_node pi_tree_entry; struct task_struct *task; struct rt_mutex *lock; #ifdef CONFIG_DEBUG_RT_MUTEXES @@ -57,11 +57,11 @@ struct rt_mutex_waiter { }; /* - * Various helpers to access the waiters-plist: + * Various helpers to access the waiters-tree: */ static inline int rt_mutex_has_waiters(struct rt_mutex *lock) { - return !plist_head_empty(&lock->wait_list); + return !RB_EMPTY_ROOT(&lock->waiters); } static inline struct rt_mutex_waiter * @@ -69,8 +69,8 @@ rt_mutex_top_waiter(struct rt_mutex *lock) { struct rt_mutex_waiter *w; - w = plist_first_entry(&lock->wait_list, struct rt_mutex_waiter, - list_entry); + w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter, + tree_entry); BUG_ON(w->lock != lock); return w; @@ -78,14 +78,14 @@ rt_mutex_top_waiter(struct rt_mutex *lock) static inline int task_has_pi_waiters(struct task_struct *p) { - return !plist_head_empty(&p->pi_waiters); + return !RB_EMPTY_ROOT(&p->pi_waiters); } static inline struct rt_mutex_waiter * task_top_pi_waiter(struct task_struct *p) { - return plist_first_entry(&p->pi_waiters, struct rt_mutex_waiter, - pi_list_entry); + return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter, + pi_tree_entry); } /* diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 069230b5c3fb..aebcc70b5c93 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6635,10 +6635,6 @@ void __init sched_init(void) INIT_HLIST_HEAD(&init_task.preempt_notifiers); #endif -#ifdef CONFIG_RT_MUTEXES - plist_head_init(&init_task.pi_waiters); -#endif - /* * The boot idle thread does lazy MMU switching as well: */ -- cgit v1.2.3-71-gd317 From 2d3d891d3344159d5b452a645e355bbe29591e8b Mon Sep 17 00:00:00 2001 From: Dario Faggioli Date: Thu, 7 Nov 2013 14:43:44 +0100 Subject: sched/deadline: Add SCHED_DEADLINE inheritance logic Some method to deal with rt-mutexes and make sched_dl interact with the current PI-coded is needed, raising all but trivial issues, that needs (according to us) to be solved with some restructuring of the pi-code (i.e., going toward a proxy execution-ish implementation). This is under development, in the meanwhile, as a temporary solution, what this commits does is: - ensure a pi-lock owner with waiters is never throttled down. Instead, when it runs out of runtime, it immediately gets replenished and it's deadline is postponed; - the scheduling parameters (relative deadline and default runtime) used for that replenishments --during the whole period it holds the pi-lock-- are the ones of the waiting task with earliest deadline. Acting this way, we provide some kind of boosting to the lock-owner, still by using the existing (actually, slightly modified by the previous commit) pi-architecture. We would stress the fact that this is only a surely needed, all but clean solution to the problem. In the end it's only a way to re-start discussion within the community. So, as always, comments, ideas, rants, etc.. are welcome! :-) Signed-off-by: Dario Faggioli Signed-off-by: Juri Lelli [ Added !RT_MUTEXES build fix. ] Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1383831828-15501-11-git-send-email-juri.lelli@gmail.com Signed-off-by: Ingo Molnar --- include/linux/sched.h | 8 +++- include/linux/sched/rt.h | 5 +++ kernel/fork.c | 1 + kernel/locking/rtmutex.c | 31 +++++++++---- kernel/locking/rtmutex_common.h | 1 + kernel/sched/core.c | 36 +++++++++++++--- kernel/sched/deadline.c | 91 +++++++++++++++++++++++---------------- kernel/sched/sched.h | 14 ++++++ kernel/trace/trace_sched_wakeup.c | 1 + 9 files changed, 134 insertions(+), 54 deletions(-) (limited to 'kernel/locking') diff --git a/include/linux/sched.h b/include/linux/sched.h index 9ea15019a5b6..13c53a99920f 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1124,8 +1124,12 @@ struct sched_dl_entity { * @dl_new tells if a new instance arrived. If so we must * start executing it with full runtime and reset its absolute * deadline; + * + * @dl_boosted tells if we are boosted due to DI. If so we are + * outside bandwidth enforcement mechanism (but only until we + * exit the critical section). */ - int dl_throttled, dl_new; + int dl_throttled, dl_new, dl_boosted; /* * Bandwidth enforcement timer. Each -deadline task has its @@ -1359,6 +1363,8 @@ struct task_struct { struct rb_node *pi_waiters_leftmost; /* Deadlock detection and priority inheritance handling */ struct rt_mutex_waiter *pi_blocked_on; + /* Top pi_waiters task */ + struct task_struct *pi_top_task; #endif #ifdef CONFIG_DEBUG_MUTEXES diff --git a/include/linux/sched/rt.h b/include/linux/sched/rt.h index 440434df3627..34e4ebea8fce 100644 --- a/include/linux/sched/rt.h +++ b/include/linux/sched/rt.h @@ -35,6 +35,7 @@ static inline int rt_task(struct task_struct *p) #ifdef CONFIG_RT_MUTEXES extern int rt_mutex_getprio(struct task_struct *p); extern void rt_mutex_setprio(struct task_struct *p, int prio); +extern struct task_struct *rt_mutex_get_top_task(struct task_struct *task); extern void rt_mutex_adjust_pi(struct task_struct *p); static inline bool tsk_is_pi_blocked(struct task_struct *tsk) { @@ -45,6 +46,10 @@ static inline int rt_mutex_getprio(struct task_struct *p) { return p->normal_prio; } +static inline struct task_struct *rt_mutex_get_top_task(struct task_struct *task) +{ + return NULL; +} # define rt_mutex_adjust_pi(p) do { } while (0) static inline bool tsk_is_pi_blocked(struct task_struct *tsk) { diff --git a/kernel/fork.c b/kernel/fork.c index 7049ae526a54..01b450a61abd 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1090,6 +1090,7 @@ static void rt_mutex_init_task(struct task_struct *p) p->pi_waiters = RB_ROOT; p->pi_waiters_leftmost = NULL; p->pi_blocked_on = NULL; + p->pi_top_task = NULL; #endif } diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 3bf0aa68dd3f..2e960a2bab81 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -96,13 +96,16 @@ static inline int rt_mutex_waiter_less(struct rt_mutex_waiter *left, struct rt_mutex_waiter *right) { - if (left->task->prio < right->task->prio) + if (left->prio < right->prio) return 1; /* - * If both tasks are dl_task(), we check their deadlines. + * If both waiters have dl_prio(), we check the deadlines of the + * associated tasks. + * If left waiter has a dl_prio(), and we didn't return 1 above, + * then right waiter has a dl_prio() too. */ - if (dl_prio(left->task->prio) && dl_prio(right->task->prio)) + if (dl_prio(left->prio)) return (left->task->dl.deadline < right->task->dl.deadline); return 0; @@ -197,10 +200,18 @@ int rt_mutex_getprio(struct task_struct *task) if (likely(!task_has_pi_waiters(task))) return task->normal_prio; - return min(task_top_pi_waiter(task)->task->prio, + return min(task_top_pi_waiter(task)->prio, task->normal_prio); } +struct task_struct *rt_mutex_get_top_task(struct task_struct *task) +{ + if (likely(!task_has_pi_waiters(task))) + return NULL; + + return task_top_pi_waiter(task)->task; +} + /* * Adjust the priority of a task, after its pi_waiters got modified. * @@ -210,7 +221,7 @@ static void __rt_mutex_adjust_prio(struct task_struct *task) { int prio = rt_mutex_getprio(task); - if (task->prio != prio) + if (task->prio != prio || dl_prio(prio)) rt_mutex_setprio(task, prio); } @@ -328,7 +339,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task, * When deadlock detection is off then we check, if further * priority adjustment is necessary. */ - if (!detect_deadlock && waiter->task->prio == task->prio) + if (!detect_deadlock && waiter->prio == task->prio) goto out_unlock_pi; lock = waiter->lock; @@ -350,7 +361,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task, /* Requeue the waiter */ rt_mutex_dequeue(lock, waiter); - waiter->task->prio = task->prio; + waiter->prio = task->prio; rt_mutex_enqueue(lock, waiter); /* Release the task */ @@ -448,7 +459,7 @@ static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task, * 3) it is top waiter */ if (rt_mutex_has_waiters(lock)) { - if (task->prio >= rt_mutex_top_waiter(lock)->task->prio) { + if (task->prio >= rt_mutex_top_waiter(lock)->prio) { if (!waiter || waiter != rt_mutex_top_waiter(lock)) return 0; } @@ -508,6 +519,7 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock, __rt_mutex_adjust_prio(task); waiter->task = task; waiter->lock = lock; + waiter->prio = task->prio; /* Get the top priority waiter on the lock */ if (rt_mutex_has_waiters(lock)) @@ -653,7 +665,8 @@ void rt_mutex_adjust_pi(struct task_struct *task) raw_spin_lock_irqsave(&task->pi_lock, flags); waiter = task->pi_blocked_on; - if (!waiter || waiter->task->prio == task->prio) { + if (!waiter || (waiter->prio == task->prio && + !dl_prio(task->prio))) { raw_spin_unlock_irqrestore(&task->pi_lock, flags); return; } diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h index b65442fe5ade..7431a9c86f35 100644 --- a/kernel/locking/rtmutex_common.h +++ b/kernel/locking/rtmutex_common.h @@ -54,6 +54,7 @@ struct rt_mutex_waiter { struct pid *deadlock_task_pid; struct rt_mutex *deadlock_lock; #endif + int prio; }; /* diff --git a/kernel/sched/core.c b/kernel/sched/core.c index aebcc70b5c93..599ee3b11b44 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -947,7 +947,7 @@ static inline void check_class_changed(struct rq *rq, struct task_struct *p, if (prev_class->switched_from) prev_class->switched_from(rq, p); p->sched_class->switched_to(rq, p); - } else if (oldprio != p->prio) + } else if (oldprio != p->prio || dl_task(p)) p->sched_class->prio_changed(rq, p, oldprio); } @@ -2781,7 +2781,7 @@ EXPORT_SYMBOL(sleep_on_timeout); */ void rt_mutex_setprio(struct task_struct *p, int prio) { - int oldprio, on_rq, running; + int oldprio, on_rq, running, enqueue_flag = 0; struct rq *rq; const struct sched_class *prev_class; @@ -2808,6 +2808,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio) } trace_sched_pi_setprio(p, prio); + p->pi_top_task = rt_mutex_get_top_task(p); oldprio = p->prio; prev_class = p->sched_class; on_rq = p->on_rq; @@ -2817,19 +2818,42 @@ void rt_mutex_setprio(struct task_struct *p, int prio) if (running) p->sched_class->put_prev_task(rq, p); - if (dl_prio(prio)) + /* + * Boosting condition are: + * 1. -rt task is running and holds mutex A + * --> -dl task blocks on mutex A + * + * 2. -dl task is running and holds mutex A + * --> -dl task blocks on mutex A and could preempt the + * running task + */ + if (dl_prio(prio)) { + if (!dl_prio(p->normal_prio) || (p->pi_top_task && + dl_entity_preempt(&p->pi_top_task->dl, &p->dl))) { + p->dl.dl_boosted = 1; + p->dl.dl_throttled = 0; + enqueue_flag = ENQUEUE_REPLENISH; + } else + p->dl.dl_boosted = 0; p->sched_class = &dl_sched_class; - else if (rt_prio(prio)) + } else if (rt_prio(prio)) { + if (dl_prio(oldprio)) + p->dl.dl_boosted = 0; + if (oldprio < prio) + enqueue_flag = ENQUEUE_HEAD; p->sched_class = &rt_sched_class; - else + } else { + if (dl_prio(oldprio)) + p->dl.dl_boosted = 0; p->sched_class = &fair_sched_class; + } p->prio = prio; if (running) p->sched_class->set_curr_task(rq); if (on_rq) - enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0); + enqueue_task(rq, p, enqueue_flag); check_class_changed(rq, p, prev_class, oldprio); out_unlock: diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 3958bc576d67..7f6de4316990 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -16,20 +16,6 @@ */ #include "sched.h" -static inline int dl_time_before(u64 a, u64 b) -{ - return (s64)(a - b) < 0; -} - -/* - * Tells if entity @a should preempt entity @b. - */ -static inline -int dl_entity_preempt(struct sched_dl_entity *a, struct sched_dl_entity *b) -{ - return dl_time_before(a->deadline, b->deadline); -} - static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se) { return container_of(dl_se, struct task_struct, dl); @@ -242,7 +228,8 @@ static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p, * one, and to (try to!) reconcile itself with its own scheduling * parameters. */ -static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se) +static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se, + struct sched_dl_entity *pi_se) { struct dl_rq *dl_rq = dl_rq_of_se(dl_se); struct rq *rq = rq_of_dl_rq(dl_rq); @@ -254,8 +241,8 @@ static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se) * future; in fact, we must consider execution overheads (time * spent on hardirq context, etc.). */ - dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline; - dl_se->runtime = dl_se->dl_runtime; + dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; + dl_se->runtime = pi_se->dl_runtime; dl_se->dl_new = 0; } @@ -277,11 +264,23 @@ static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se) * could happen are, typically, a entity voluntarily trying to overcome its * runtime, or it just underestimated it during sched_setscheduler_ex(). */ -static void replenish_dl_entity(struct sched_dl_entity *dl_se) +static void replenish_dl_entity(struct sched_dl_entity *dl_se, + struct sched_dl_entity *pi_se) { struct dl_rq *dl_rq = dl_rq_of_se(dl_se); struct rq *rq = rq_of_dl_rq(dl_rq); + BUG_ON(pi_se->dl_runtime <= 0); + + /* + * This could be the case for a !-dl task that is boosted. + * Just go with full inherited parameters. + */ + if (dl_se->dl_deadline == 0) { + dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; + dl_se->runtime = pi_se->dl_runtime; + } + /* * We keep moving the deadline away until we get some * available runtime for the entity. This ensures correct @@ -289,8 +288,8 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se) * arbitrary large. */ while (dl_se->runtime <= 0) { - dl_se->deadline += dl_se->dl_period; - dl_se->runtime += dl_se->dl_runtime; + dl_se->deadline += pi_se->dl_period; + dl_se->runtime += pi_se->dl_runtime; } /* @@ -309,8 +308,8 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se) lag_once = true; printk_sched("sched: DL replenish lagged to much\n"); } - dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline; - dl_se->runtime = dl_se->dl_runtime; + dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; + dl_se->runtime = pi_se->dl_runtime; } } @@ -337,7 +336,8 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se) * task with deadline equal to period this is the same of using * dl_deadline instead of dl_period in the equation above. */ -static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t) +static bool dl_entity_overflow(struct sched_dl_entity *dl_se, + struct sched_dl_entity *pi_se, u64 t) { u64 left, right; @@ -359,8 +359,8 @@ static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t) * of anything below microseconds resolution is actually fiction * (but still we want to give the user that illusion >;). */ - left = (dl_se->dl_period >> 10) * (dl_se->runtime >> 10); - right = ((dl_se->deadline - t) >> 10) * (dl_se->dl_runtime >> 10); + left = (pi_se->dl_period >> 10) * (dl_se->runtime >> 10); + right = ((dl_se->deadline - t) >> 10) * (pi_se->dl_runtime >> 10); return dl_time_before(right, left); } @@ -374,7 +374,8 @@ static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t) * - using the remaining runtime with the current deadline would make * the entity exceed its bandwidth. */ -static void update_dl_entity(struct sched_dl_entity *dl_se) +static void update_dl_entity(struct sched_dl_entity *dl_se, + struct sched_dl_entity *pi_se) { struct dl_rq *dl_rq = dl_rq_of_se(dl_se); struct rq *rq = rq_of_dl_rq(dl_rq); @@ -384,14 +385,14 @@ static void update_dl_entity(struct sched_dl_entity *dl_se) * the actual scheduling parameters have to be "renewed". */ if (dl_se->dl_new) { - setup_new_dl_entity(dl_se); + setup_new_dl_entity(dl_se, pi_se); return; } if (dl_time_before(dl_se->deadline, rq_clock(rq)) || - dl_entity_overflow(dl_se, rq_clock(rq))) { - dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline; - dl_se->runtime = dl_se->dl_runtime; + dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) { + dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; + dl_se->runtime = pi_se->dl_runtime; } } @@ -405,7 +406,7 @@ static void update_dl_entity(struct sched_dl_entity *dl_se) * actually started or not (i.e., the replenishment instant is in * the future or in the past). */ -static int start_dl_timer(struct sched_dl_entity *dl_se) +static int start_dl_timer(struct sched_dl_entity *dl_se, bool boosted) { struct dl_rq *dl_rq = dl_rq_of_se(dl_se); struct rq *rq = rq_of_dl_rq(dl_rq); @@ -414,6 +415,8 @@ static int start_dl_timer(struct sched_dl_entity *dl_se) unsigned long range; s64 delta; + if (boosted) + return 0; /* * We want the timer to fire at the deadline, but considering * that it is actually coming from rq->clock and not from @@ -573,7 +576,7 @@ static void update_curr_dl(struct rq *rq) dl_se->runtime -= delta_exec; if (dl_runtime_exceeded(rq, dl_se)) { __dequeue_task_dl(rq, curr, 0); - if (likely(start_dl_timer(dl_se))) + if (likely(start_dl_timer(dl_se, curr->dl.dl_boosted))) dl_se->dl_throttled = 1; else enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH); @@ -728,7 +731,8 @@ static void __dequeue_dl_entity(struct sched_dl_entity *dl_se) } static void -enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags) +enqueue_dl_entity(struct sched_dl_entity *dl_se, + struct sched_dl_entity *pi_se, int flags) { BUG_ON(on_dl_rq(dl_se)); @@ -738,9 +742,9 @@ enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags) * we want a replenishment of its runtime. */ if (!dl_se->dl_new && flags & ENQUEUE_REPLENISH) - replenish_dl_entity(dl_se); + replenish_dl_entity(dl_se, pi_se); else - update_dl_entity(dl_se); + update_dl_entity(dl_se, pi_se); __enqueue_dl_entity(dl_se); } @@ -752,6 +756,18 @@ static void dequeue_dl_entity(struct sched_dl_entity *dl_se) static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) { + struct task_struct *pi_task = rt_mutex_get_top_task(p); + struct sched_dl_entity *pi_se = &p->dl; + + /* + * Use the scheduling parameters of the top pi-waiter + * task if we have one and its (relative) deadline is + * smaller than our one... OTW we keep our runtime and + * deadline. + */ + if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio)) + pi_se = &pi_task->dl; + /* * If p is throttled, we do nothing. In fact, if it exhausted * its budget it needs a replenishment and, since it now is on @@ -761,7 +777,7 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) if (p->dl.dl_throttled) return; - enqueue_dl_entity(&p->dl, flags); + enqueue_dl_entity(&p->dl, pi_se, flags); if (!task_current(rq, p) && p->nr_cpus_allowed > 1) enqueue_pushable_dl_task(rq, p); @@ -985,8 +1001,7 @@ static void task_dead_dl(struct task_struct *p) { struct hrtimer *timer = &p->dl.dl_timer; - if (hrtimer_active(timer)) - hrtimer_try_to_cancel(timer); + hrtimer_cancel(timer); } static void set_curr_task_dl(struct rq *rq) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 93ea62754f11..52453a2d0a79 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -107,6 +107,20 @@ static inline int task_has_dl_policy(struct task_struct *p) return dl_policy(p->policy); } +static inline int dl_time_before(u64 a, u64 b) +{ + return (s64)(a - b) < 0; +} + +/* + * Tells if entity @a should preempt entity @b. + */ +static inline +int dl_entity_preempt(struct sched_dl_entity *a, struct sched_dl_entity *b) +{ + return dl_time_before(a->deadline, b->deadline); +} + /* * This is the priority-queue data structure of the RT scheduling class: */ diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index 090c4d9dcf16..6e32635e5e57 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include "trace.h" -- cgit v1.2.3-71-gd317