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Release 4.15 kernel/locking/rtmutex.c

Directory: kernel/locking
/*
 * RT-Mutexes: simple blocking mutual exclusion locks with PI support
 *
 * started by Ingo Molnar and Thomas Gleixner.
 *
 *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *  Copyright (C) 2005-2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
 *  Copyright (C) 2005 Kihon Technologies Inc., Steven Rostedt
 *  Copyright (C) 2006 Esben Nielsen
 *
 *  See Documentation/locking/rt-mutex-design.txt for details.
 */
#include <linux/spinlock.h>
#include <linux/export.h>
#include <linux/sched/signal.h>
#include <linux/sched/rt.h>
#include <linux/sched/deadline.h>
#include <linux/sched/wake_q.h>
#include <linux/sched/debug.h>
#include <linux/timer.h>

#include "rtmutex_common.h"

/*
 * lock->owner state tracking:
 *
 * lock->owner holds the task_struct pointer of the owner. Bit 0
 * is used to keep track of the "lock has waiters" state.
 *
 * owner        bit0
 * NULL         0       lock is free (fast acquire possible)
 * NULL         1       lock is free and has waiters and the top waiter
 *                              is going to take the lock*
 * taskpointer  0       lock is held (fast release possible)
 * taskpointer  1       lock is held and has waiters**
 *
 * The fast atomic compare exchange based acquire and release is only
 * possible when bit 0 of lock->owner is 0.
 *
 * (*) It also can be a transitional state when grabbing the lock
 * with ->wait_lock is held. To prevent any fast path cmpxchg to the lock,
 * we need to set the bit0 before looking at the lock, and the owner may be
 * NULL in this small time, hence this can be a transitional state.
 *
 * (**) There is a small time when bit 0 is set but there are no
 * waiters. This can happen when grabbing the lock in the slow path.
 * To prevent a cmpxchg of the owner releasing the lock, we need to
 * set this bit before looking at the lock.
 */


static void rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner) { unsigned long val = (unsigned long)owner; if (rt_mutex_has_waiters(lock)) val |= RT_MUTEX_HAS_WAITERS; lock->owner = (struct task_struct *)val; }

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Ingo Molnar4797.92%150.00%
Thomas Gleixner12.08%150.00%
Total48100.00%2100.00%


static inline void clear_rt_mutex_waiters(struct rt_mutex *lock) { lock->owner = (struct task_struct *) ((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS); }

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Ingo Molnar34100.00%1100.00%
Total34100.00%1100.00%


static void fixup_rt_mutex_waiters(struct rt_mutex *lock) { unsigned long owner, *p = (unsigned long *) &lock->owner; if (rt_mutex_has_waiters(lock)) return; /* * The rbtree has no waiters enqueued, now make sure that the * lock->owner still has the waiters bit set, otherwise the * following can happen: * * CPU 0 CPU 1 CPU2 * l->owner=T1 * rt_mutex_lock(l) * lock(l->lock) * l->owner = T1 | HAS_WAITERS; * enqueue(T2) * boost() * unlock(l->lock) * block() * * rt_mutex_lock(l) * lock(l->lock) * l->owner = T1 | HAS_WAITERS; * enqueue(T3) * boost() * unlock(l->lock) * block() * signal(->T2) signal(->T3) * lock(l->lock) * dequeue(T2) * deboost() * unlock(l->lock) * lock(l->lock) * dequeue(T3) * ==> wait list is empty * deboost() * unlock(l->lock) * lock(l->lock) * fixup_rt_mutex_waiters() * if (wait_list_empty(l) { * l->owner = owner * owner = l->owner & ~HAS_WAITERS; * ==> l->owner = T1 * } * lock(l->lock) * rt_mutex_unlock(l) fixup_rt_mutex_waiters() * if (wait_list_empty(l) { * owner = l->owner & ~HAS_WAITERS; * cmpxchg(l->owner, T1, NULL) * ===> Success (l->owner = NULL) * * l->owner = owner * ==> l->owner = T1 * } * * With the check for the waiter bit in place T3 on CPU2 will not * overwrite. All tasks fiddling with the waiters bit are * serialized by l->lock, so nothing else can modify the waiters * bit. If the bit is set then nothing can change l->owner either * so the simple RMW is safe. The cmpxchg() will simply fail if it * happens in the middle of the RMW because the waiters bit is * still set. */ owner = READ_ONCE(*p); if (owner & RT_MUTEX_HAS_WAITERS) WRITE_ONCE(*p, owner & ~RT_MUTEX_HAS_WAITERS); }

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Thomas Gleixner4166.13%150.00%
Ingo Molnar2133.87%150.00%
Total62100.00%2100.00%

/* * We can speed up the acquire/release, if there's no debugging state to be * set up. */ #ifndef CONFIG_DEBUG_RT_MUTEXES # define rt_mutex_cmpxchg_relaxed(l,c,n) (cmpxchg_relaxed(&l->owner, c, n) == c) # define rt_mutex_cmpxchg_acquire(l,c,n) (cmpxchg_acquire(&l->owner, c, n) == c) # define rt_mutex_cmpxchg_release(l,c,n) (cmpxchg_release(&l->owner, c, n) == c) /* * Callers must hold the ->wait_lock -- which is the whole purpose as we force * all future threads that attempt to [Rmw] the lock to the slowpath. As such * relaxed semantics suffice. */
static inline void mark_rt_mutex_waiters(struct rt_mutex *lock) { unsigned long owner, *p = (unsigned long *) &lock->owner; do { owner = *p; } while (cmpxchg_relaxed(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner); }

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Thomas Gleixner5298.11%150.00%
Davidlohr Bueso A11.89%150.00%
Total53100.00%2100.00%

/* * Safe fastpath aware unlock: * 1) Clear the waiters bit * 2) Drop lock->wait_lock * 3) Try to unlock the lock with cmpxchg */
static inline bool unlock_rt_mutex_safe(struct rt_mutex *lock, unsigned long flags) __releases(lock->wait_lock) { struct task_struct *owner = rt_mutex_owner(lock); clear_rt_mutex_waiters(lock); raw_spin_unlock_irqrestore(&lock->wait_lock, flags); /* * If a new waiter comes in between the unlock and the cmpxchg * we have two situations: * * unlock(wait_lock); * lock(wait_lock); * cmpxchg(p, owner, 0) == owner * mark_rt_mutex_waiters(lock); * acquire(lock); * or: * * unlock(wait_lock); * lock(wait_lock); * mark_rt_mutex_waiters(lock); * * cmpxchg(p, owner, 0) != owner * enqueue_waiter(); * unlock(wait_lock); * lock(wait_lock); * wake waiter(); * unlock(wait_lock); * lock(wait_lock); * acquire(lock); */ return rt_mutex_cmpxchg_release(lock, owner, NULL); }

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Thomas Gleixner5798.28%266.67%
Davidlohr Bueso A11.72%133.33%
Total58100.00%3100.00%

#else # define rt_mutex_cmpxchg_relaxed(l,c,n) (0) # define rt_mutex_cmpxchg_acquire(l,c,n) (0) # define rt_mutex_cmpxchg_release(l,c,n) (0)
static inline void mark_rt_mutex_waiters(struct rt_mutex *lock) { lock->owner = (struct task_struct *) ((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS); }

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Peter Zijlstra2060.61%150.00%
Thomas Gleixner1339.39%150.00%
Total33100.00%2100.00%

/* * Simple slow path only version: lock->owner is protected by lock->wait_lock. */
static inline bool unlock_rt_mutex_safe(struct rt_mutex *lock, unsigned long flags) __releases(lock->wait_lock) { lock->owner = NULL; raw_spin_unlock_irqrestore(&lock->wait_lock, flags); return true; }

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Thomas Gleixner41100.00%2100.00%
Total41100.00%2100.00%

#endif /* * Only use with rt_mutex_waiter_{less,equal}() */ #define task_to_waiter(p) \ &(struct rt_mutex_waiter){ .prio = (p)->prio, .deadline = (p)->dl.deadline }
static inline int rt_mutex_waiter_less(struct rt_mutex_waiter *left, struct rt_mutex_waiter *right) { if (left->prio < right->prio) return 1; /* * 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->prio)) return dl_time_before(left->deadline, right->deadline); return 0; }

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Peter Zijlstra5090.91%133.33%
Juri Lelli47.27%133.33%
Dario Faggioli11.82%133.33%
Total55100.00%3100.00%


static inline int rt_mutex_waiter_equal(struct rt_mutex_waiter *left, struct rt_mutex_waiter *right) { if (left->prio != right->prio) return 0; /* * 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 0 above, * then right waiter has a dl_prio() too. */ if (dl_prio(left->prio)) return left->deadline == right->deadline; return 1; }

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Peter Zijlstra52100.00%2100.00%
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static void rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter) { struct rb_node **link = &lock->waiters.rb_root.rb_node; struct rb_node *parent = NULL; struct rt_mutex_waiter *entry; bool leftmost = true; 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 = false; } } rb_link_node(&waiter->tree_entry, parent, link); rb_insert_color_cached(&waiter->tree_entry, &lock->waiters, leftmost); }

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Peter Zijlstra12393.89%266.67%
Davidlohr Bueso A86.11%133.33%
Total131100.00%3100.00%


static void rt_mutex_dequeue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter) { if (RB_EMPTY_NODE(&waiter->tree_entry)) return; rb_erase_cached(&waiter->tree_entry, &lock->waiters); RB_CLEAR_NODE(&waiter->tree_entry); }

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Peter Zijlstra4797.92%150.00%
Davidlohr Bueso A12.08%150.00%
Total48100.00%2100.00%


static void rt_mutex_enqueue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter) { struct rb_node **link = &task->pi_waiters.rb_root.rb_node; struct rb_node *parent = NULL; struct rt_mutex_waiter *entry; bool leftmost = true; 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 = false; } } rb_link_node(&waiter->pi_tree_entry, parent, link); rb_insert_color_cached(&waiter->pi_tree_entry, &task->pi_waiters, leftmost); }

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Peter Zijlstra12393.89%150.00%
Davidlohr Bueso A86.11%150.00%
Total131100.00%2100.00%


static void rt_mutex_dequeue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter) { if (RB_EMPTY_NODE(&waiter->pi_tree_entry)) return; rb_erase_cached(&waiter->pi_tree_entry, &task->pi_waiters); RB_CLEAR_NODE(&waiter->pi_tree_entry); }

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Peter Zijlstra4491.67%133.33%
Thomas Gleixner36.25%133.33%
Davidlohr Bueso A12.08%133.33%
Total48100.00%3100.00%


static void rt_mutex_adjust_prio(struct task_struct *p) { struct task_struct *pi_task = NULL; lockdep_assert_held(&p->pi_lock); if (task_has_pi_waiters(p)) pi_task = task_top_pi_waiter(p)->task; rt_mutex_setprio(p, pi_task); }

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Peter Zijlstra1938.78%120.00%
Ingo Molnar1530.61%120.00%
Xunlei Pang1326.53%120.00%
Thomas Gleixner24.08%240.00%
Total49100.00%5100.00%

/* * Deadlock detection is conditional: * * If CONFIG_DEBUG_RT_MUTEXES=n, deadlock detection is only conducted * if the detect argument is == RT_MUTEX_FULL_CHAINWALK. * * If CONFIG_DEBUG_RT_MUTEXES=y, deadlock detection is always * conducted independent of the detect argument. * * If the waiter argument is NULL this indicates the deboost path and * deadlock detection is disabled independent of the detect argument * and the config settings. */
static bool rt_mutex_cond_detect_deadlock(struct rt_mutex_waiter *waiter, enum rtmutex_chainwalk chwalk) { /* * This is just a wrapper function for the following call, * because debug_rt_mutex_detect_deadlock() smells like a magic * debug feature and I wanted to keep the cond function in the * main source file along with the comments instead of having * two of the same in the headers. */ return debug_rt_mutex_detect_deadlock(waiter, chwalk); }

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Thomas Gleixner24100.00%1100.00%
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/* * Max number of times we'll walk the boosting chain: */ int max_lock_depth = 1024;
static inline struct rt_mutex *task_blocked_on_lock(struct task_struct *p) { return p->pi_blocked_on ? p->pi_blocked_on->lock : NULL; }

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Thomas Gleixner27100.00%1100.00%
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/* * Adjust the priority chain. Also used for deadlock detection. * Decreases task's usage by one - may thus free the task. * * @task: the task owning the mutex (owner) for which a chain walk is * probably needed * @chwalk: do we have to carry out deadlock detection? * @orig_lock: the mutex (can be NULL if we are walking the chain to recheck * things for a task that has just got its priority adjusted, and * is waiting on a mutex) * @next_lock: the mutex on which the owner of @orig_lock was blocked before * we dropped its pi_lock. Is never dereferenced, only used for * comparison to detect lock chain changes. * @orig_waiter: rt_mutex_waiter struct for the task that has just donated * its priority to the mutex owner (can be NULL in the case * depicted above or if the top waiter is gone away and we are * actually deboosting the owner) * @top_task: the current top waiter * * Returns 0 or -EDEADLK. * * Chain walk basics and protection scope * * [R] refcount on task * [P] task->pi_lock held * [L] rtmutex->wait_lock held * * Step Description Protected by * function arguments: * @task [R] * @orig_lock if != NULL @top_task is blocked on it * @next_lock Unprotected. Cannot be * dereferenced. Only used for * comparison. * @orig_waiter if != NULL @top_task is blocked on it * @top_task current, or in case of proxy * locking protected by calling * code * again: * loop_sanity_check(); * retry: * [1] lock(task->pi_lock); [R] acquire [P] * [2] waiter = task->pi_blocked_on; [P] * [3] check_exit_conditions_1(); [P] * [4] lock = waiter->lock; [P] * [5] if (!try_lock(lock->wait_lock)) { [P] try to acquire [L] * unlock(task->pi_lock); release [P] * goto retry; * } * [6] check_exit_conditions_2(); [P] + [L] * [7] requeue_lock_waiter(lock, waiter); [P] + [L] * [8] unlock(task->pi_lock); release [P] * put_task_struct(task); release [R] * [9] check_exit_conditions_3(); [L] * [10] task = owner(lock); [L] * get_task_struct(task); [L] acquire [R] * lock(task->pi_lock); [L] acquire [P] * [11] requeue_pi_waiter(tsk, waiters(lock));[P] + [L] * [12] check_exit_conditions_4(); [P] + [L] * [13] unlock(task->pi_lock); release [P] * unlock(lock->wait_lock); release [L] * goto again; */
static int rt_mutex_adjust_prio_chain(struct task_struct *task, enum rtmutex_chainwalk chwalk, struct rt_mutex *orig_lock, struct rt_mutex *next_lock, struct rt_mutex_waiter *orig_waiter, struct task_struct *top_task) { struct rt_mutex_waiter *waiter, *top_waiter = orig_waiter; struct rt_mutex_waiter *prerequeue_top_waiter; int ret = 0, depth = 0; struct rt_mutex *lock; bool detect_deadlock; bool requeue = true; detect_deadlock = rt_mutex_cond_detect_deadlock(orig_waiter, chwalk); /* * The (de)boosting is a step by step approach with a lot of * pitfalls. We want this to be preemptible and we want hold a * maximum of two locks per step. So we have to check * carefully whether things change under us. */ again: /* * We limit the lock chain length for each invocation. */ if (++depth > max_lock_depth) { static int prev_max; /* * Print this only once. If the admin changes the limit, * print a new message when reaching the limit again. */ if (prev_max != max_lock_depth) { prev_max = max_lock_depth; printk(KERN_WARNING "Maximum lock depth %d reached " "task: %s (%d)\n", max_lock_depth, top_task->comm, task_pid_nr(top_task)); } put_task_struct(task); return -EDEADLK; } /* * We are fully preemptible here and only hold the refcount on * @task. So everything can have changed under us since the * caller or our own code below (goto retry/again) dropped all * locks. */ retry: /* * [1] Task cannot go away as we did a get_task() before ! */ raw_spin_lock_irq(&task->pi_lock); /* * [2] Get the waiter on which @task is blocked on. */ waiter = task->pi_blocked_on; /* * [3] check_exit_conditions_1() protected by task->pi_lock. */ /* * Check whether the end of the boosting chain has been * reached or the state of the chain has changed while we * dropped the locks. */ if (!waiter) goto out_unlock_pi; /* * Check the orig_waiter state. After we dropped the locks, * the previous owner of the lock might have released the lock. */ if (orig_waiter && !rt_mutex_owner(orig_lock)) goto out_unlock_pi; /* * We dropped all locks after taking a refcount on @task, so * the task might have moved on in the lock chain or even left * the chain completely and blocks now on an unrelated lock or * on @orig_lock. * * We stored the lock on which @task was blocked in @next_lock, * so we can detect the chain change. */ if (next_lock != waiter->lock) goto out_unlock_pi; /* * Drop out, when the task has no waiters. Note, * top_waiter can be NULL, when we are in the deboosting * mode! */ if (top_waiter) { if (!task_has_pi_waiters(task)) goto out_unlock_pi; /* * If deadlock detection is off, we stop here if we * are not the top pi waiter of the task. If deadlock * detection is enabled we continue, but stop the * requeueing in the chain walk. */ if (top_waiter != task_top_pi_waiter(task)) { if (!detect_deadlock) goto out_unlock_pi; else requeue = false; } } /* * If the waiter priority is the same as the task priority * then there is no further priority adjustment necessary. If * deadlock detection is off, we stop the chain walk. If its * enabled we continue, but stop the requeueing in the chain * walk. */ if (rt_mutex_waiter_equal(waiter, task_to_waiter(task))) { if (!detect_deadlock) goto out_unlock_pi; else requeue = false; } /* * [4] Get the next lock */ lock = waiter->lock; /* * [5] We need to trylock here as we are holding task->pi_lock, * which is the reverse lock order versus the other rtmutex * operations. */ if (!raw_spin_trylock(&lock->wait_lock)) { raw_spin_unlock_irq(&task->pi_lock); cpu_relax(); goto retry; } /* * [6] check_exit_conditions_2() protected by task->pi_lock and * lock->wait_lock. * * Deadlock detection. If the lock is the same as the original * lock which caused us to walk the lock chain or if the * current lock is owned by the task which initiated the chain * walk, we detected a deadlock. */ if (lock == orig_lock || rt_mutex_owner(lock) == top_task) { debug_rt_mutex_deadlock(chwalk, orig_waiter, lock); raw_spin_unlock(&lock->wait_lock); ret = -EDEADLK; goto out_unlock_pi; } /* * If we just follow the lock chain for deadlock detection, no * need to do all the requeue operations. To avoid a truckload * of conditionals around the various places below, just do the * minimum chain walk checks. */ if (!requeue) { /* * No requeue[7] here. Just release @task [8] */ raw_spin_unlock(&task->pi_lock); put_task_struct(task); /* * [9] check_exit_conditions_3 protected by lock->wait_lock. * If there is no owner of the lock, end of chain. */ if (!rt_mutex_owner(lock)) { raw_spin_unlock_irq(&lock->wait_lock); return 0; } /* [10] Grab the next task, i.e. owner of @lock */ task = rt_mutex_owner(lock); get_task_struct(task); raw_spin_lock(&task->pi_lock); /* * No requeue [11] here. We just do deadlock detection. * * [12] Store whether owner is blocked * itself. Decision is made after dropping the locks */ next_lock = task_blocked_on_lock(task); /* * Get the top waiter for the next iteration */ top_waiter = rt_mutex_top_waiter(lock); /* [13] Drop locks */ raw_spin_unlock(&task->pi_lock); raw_spin_unlock_irq(&lock->wait_lock); /* If owner is not blocked, end of chain. */ if (!next_lock) goto out_put_task; goto again; } /* * Store the current top waiter before doing the requeue * operation on @lock. We need it for the boost/deboost * decision below. */ prerequeue_top_waiter = rt_mutex_top_waiter(lock); /* [7] Requeue the waiter in the lock waiter tree. */ rt_mutex_dequeue(lock, waiter); /* * Update the waiter prio fields now that we're dequeued. * * These values can have changed through either: * * sys_sched_set_scheduler() / sys_sched_setattr() * * or * * DL CBS enforcement advancing the effective deadline. * * Even though pi_waiters also uses these fields, and that tree is only * updated in [11], we can do this here, since we hold [L], which * serializes all pi_waiters access and rb_erase() does not care about * the values of the node being removed. */ waiter->prio = task->prio; waiter->deadline = task->dl.deadline; rt_mutex_enqueue(lock, waiter); /* [8] Release the task */ raw_spin_unlock(&task->pi_lock); put_task_struct(task); /* * [9] check_exit_conditions_3 protected by lock->wait_lock. * * We must abort the chain walk if there is no lock owner even * in the dead lock detection case, as we have nothing to * follow here. This is the end of the chain we are walking. */ if (!rt_mutex_owner(lock)) { /* * If the requeue [7] above changed the top waiter, * then we need to wake the new top waiter up to try * to get the lock. */ if (prerequeue_top_waiter != rt_mutex_top_waiter(lock)) wake_up_process(rt_mutex_top_waiter(lock)->task); raw_spin_unlock_irq(&lock->wait_lock); return 0; } /* [10] Grab the next task, i.e. the owner of @lock */ task = rt_mutex_owner(lock); get_task_struct(task); raw_spin_lock(&task->pi_lock); /* [11] requeue the pi waiters if necessary */ if (waiter == rt_mutex_top_waiter(lock)) { /* * The waiter became the new top (highest priority) * waiter on the lock. Replace the previous top waiter * in the owner tasks pi waiters tree with this waiter * and adjust the priority of the owner. */ rt_mutex_dequeue_pi(task, prerequeue_top_waiter); rt_mutex_enqueue_pi(task, waiter); rt_mutex_adjust_prio(task); } else if (prerequeue_top_waiter == waiter) { /* * The waiter was the top waiter on the lock, but is * no longer the top prority waiter. Replace waiter in * the owner tasks pi waiters tree with the new top * (highest priority) waiter and adjust the priority * of the owner. * The new top waiter is stored in @waiter so that * @waiter == @top_waiter evaluates to true below and * we continue to deboost the rest of the chain. */ rt_mutex_dequeue_pi(task, waiter); waiter = rt_mutex_top_waiter(lock); rt_mutex_enqueue_pi(task, waiter); rt_mutex_adjust_prio(task); } else { /* * Nothing changed. No need to do any priority * adjustment. */ } /* * [12] check_exit_conditions_4() protected by task->pi_lock * and lock->wait_lock. The actual decisions are made after we * dropped the locks. * * Check whether the task which owns the current lock is pi * blocked itself. If yes we store a pointer to the lock for * the lock chain change detection above. After we dropped * task->pi_lock next_lock cannot be dereferenced anymore. */ next_lock = task_blocked_on_lock(task); /* * Store the top waiter of @lock for the end of chain walk * decision below. */ top_waiter = rt_mutex_top_waiter(lock); /* [13] Drop the locks */ raw_spin_unlock(&task->pi_lock); raw_spin_unlock_irq(&lock->wait_lock); /* * Make the actual exit decisions [12], based on the stored * values. * * We reached the end of the lock chain. Stop right here. No * point to go back just to figure that out. */ if (!next_lock) goto out_put_task; /* * If the current waiter is not the top waiter on the lock, * then we can stop the chain walk here if we are not in full * deadlock detection mode. */ if (!detect_deadlock && waiter != top_waiter) goto out_put_task; goto again; out_unlock_pi: raw_spin_unlock_irq(&task->pi_lock); out_put_task: put_task_struct(task); return ret; }

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Ingo Molnar35649.51%28.70%
Thomas Gleixner27438.11%1252.17%
Lai Jiangshan405.56%14.35%
Peter Zijlstra354.87%417.39%
Steven Rostedt50.70%14.35%
Davidlohr Bueso A30.42%14.35%
Pavel Emelyanov30.42%14.35%
Xunlei Pang30.42%14.35%
Total719100.00%23100.00%

/* * Try to take an rt-mutex * * Must be called with lock->wait_lock held and interrupts disabled * * @lock: The lock to be acquired. * @task: The task which wants to acquire the lock * @waiter: The waiter that is queued to the lock's wait tree if the * callsite called task_blocked_on_lock(), otherwise NULL */
static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task, struct rt_mutex_waiter *waiter) { lockdep_assert_held(&lock->wait_lock); /* * Before testing whether we can acquire @lock, we set the * RT_MUTEX_HAS_WAITERS bit in @lock->owner. This forces all * other tasks which try to modify @lock into the slow path * and they serialize on @lock->wait_lock. * * The RT_MUTEX_HAS_WAITERS bit can have a transitional state * as explained at the top of this file if and only if: * * - There is a lock owner. The caller must fixup the * transient state if it does a trylock or leaves the lock * function due to a signal or timeout. * * - @task acquires the lock and there are no other * waiters. This is undone in rt_mutex_set_owner(@task) at * the end of this function. */ mark_rt_mutex_waiters(lock); /* * If @lock has an owner, give up. */ if (rt_mutex_owner(lock)) return 0; /* * If @waiter != NULL, @task has already enqueued the waiter * into @lock waiter tree. If @waiter == NULL then this is a * trylock attempt. */ if (waiter) { /* * If waiter is not the highest priority waiter of * @lock, give up. */ if (waiter != rt_mutex_top_waiter(lock)) return 0; /* * We can acquire the lock. Remove the waiter from the * lock waiters tree. */ rt_mutex_dequeue(lock, waiter); } else { /* * If the lock has waiters already we check whether @task is * eligible to take over the lock. * * If there are no other waiters, @task can acquire * the lock. @task->pi_blocked_on is NULL, so it does * not need to be dequeued. */ if (rt_mutex_has_waiters(lock)) { /* * If @task->prio is greater than or equal to * the top waiter priority (kernel view), * @task lost. */ if (!rt_mutex_waiter_less(task_to_waiter(task), rt_mutex_top_waiter(lock))) return 0; /* * The current top waiter stays enqueued. We * don't have to change anything in the lock * waiters order. */ } else { /* * No waiters. Take the lock without the * pi_lock dance.@task->pi_blocked_on is NULL * and we have no waiters to enqueue in @task * pi waiters tree. */ goto takeit; } } /* * Clear @task->pi_blocked_on. Requires protection by * @task->pi_lock. Redundant operation for the @waiter == NULL * case, but conditionals are more expensive than a redundant * store. */ raw_spin_lock(&task->pi_lock); task->pi_blocked_on = NULL; /* * Finish the lock acquisition. @task is the new owner. If * other waiters exist we have to insert the highest priority * waiter into @task->pi_waiters tree. */ if (rt_mutex_has_waiters(lock)) rt_mutex_enqueue_pi(task, rt_mutex_top_waiter(lock)); raw_spin_unlock(&task->pi_lock); takeit: /* We got the lock. */ debug_rt_mutex_lock(lock); /* * This either preserves the RT_MUTEX_HAS_WAITERS bit if there * are still waiters or clears it. */ rt_mutex_set_owner(lock, task); return 1; }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar7442.29%220.00%
Thomas Gleixner4425.14%220.00%
Lai Jiangshan2816.00%110.00%
Peter Zijlstra1810.29%330.00%
Darren Hart74.00%110.00%
Davidlohr Bueso A42.29%110.00%
Total175100.00%10100.00%

/* * Task blocks on lock. * * Prepare waiter and propagate pi chain * * This must be called with lock->wait_lock held and interrupts disabled */
static int task_blocks_on_rt_mutex(struct rt_mutex *lock, struct rt_mutex_waiter *waiter, struct task_struct *task, enum rtmutex_chainwalk chwalk) { struct task_struct *owner = rt_mutex_owner(lock); struct rt_mutex_waiter *top_waiter = waiter; struct rt_mutex *next_lock; int chain_walk = 0, res; lockdep_assert_held(&lock->wait_lock); /* * Early deadlock detection. We really don't want the task to * enqueue on itself just to untangle the mess later. It's not * only an optimization. We drop the locks, so another waiter * can come in before the chain walk detects the deadlock. So * the other will detect the deadlock and return -EDEADLOCK, * which is wrong, as the other waiter is not in a deadlock * situation. */ if (owner == task) return -EDEADLK; raw_spin_lock(&task->pi_lock); waiter->task = task; waiter->lock = lock; waiter->prio = task->prio; waiter->deadline = task->dl.deadline; /* Get the top priority waiter on the lock */ if (rt_mutex_has_waiters(lock)) top_waiter = rt_mutex_top_waiter(lock); rt_mutex_enqueue(lock, waiter); task->pi_blocked_on = waiter; raw_spin_unlock(&task->pi_lock); if (!owner) return 0; raw_spin_lock(&owner->pi_lock); if (waiter == rt_mutex_top_waiter(lock)) { rt_mutex_dequeue_pi(owner, top_waiter); rt_mutex_enqueue_pi(owner, waiter); rt_mutex_adjust_prio(owner); if (owner->pi_blocked_on) chain_walk = 1; } else if (rt_mutex_cond_detect_deadlock(waiter, chwalk)) { chain_walk = 1; } /* Store the lock on which owner is blocked or NULL */ next_lock = task_blocked_on_lock(owner); raw_spin_unlock(&owner->pi_lock); /* * Even if full deadlock detection is on, if the owner is not * blocked itself, we can avoid finding this out in the chain * walk. */ if (!chain_walk || !next_lock) return 0; /* * The owner can't disappear while holding a lock, * so the owner struct is protected by wait_lock. * Gets dropped in rt_mutex_adjust_prio_chain()! */ get_task_struct(owner); raw_spin_unlock_irq(&lock->wait_lock); res = rt_mutex_adjust_prio_chain(owner, chwalk, lock, next_lock, waiter, task); raw_spin_lock_irq(&lock->wait_lock); return res; }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar16657.44%320.00%
Thomas Gleixner6121.11%533.33%
Peter Zijlstra289.69%320.00%
Steven Rostedt103.46%16.67%
Darren Hart103.46%16.67%
Dario Faggioli82.77%16.67%
Lai Jiangshan62.08%16.67%
Total289100.00%15100.00%

/* * Remove the top waiter from the current tasks pi waiter tree and * queue it up. * * Called with lock->wait_lock held and interrupts disabled. */
static void mark_wakeup_next_waiter(struct wake_q_head *wake_q, struct rt_mutex *lock) { struct rt_mutex_waiter *waiter; raw_spin_lock(&current->pi_lock); waiter = rt_mutex_top_waiter(lock); /* * Remove it from current->pi_waiters and deboost. * * We must in fact deboost here in order to ensure we call * rt_mutex_setprio() to update p->pi_top_task before the * task unblocks. */ rt_mutex_dequeue_pi(current, waiter); rt_mutex_adjust_prio(current); /* * As we are waking up the top waiter, and the waiter stays * queued on the lock until it gets the lock, this lock * obviously has waiters. Just set the bit here and this has * the added benefit of forcing all new tasks into the * slow path making sure no task of lower priority than * the top waiter can steal this lock. */ lock->owner = (void *) RT_MUTEX_HAS_WAITERS; /* * We deboosted before waking the top waiter task such that we don't * run two tasks with the 'same' priority (and ensure the * p->pi_top_task pointer points to a blocked task). This however can * lead to priority inversion if we would get preempted after the * deboost but before waking our donor task, hence the preempt_disable() * before unlock. * * Pairs with preempt_enable() in rt_mutex_postunlock(); */ preempt_disable(); wake_q_add(wake_q, waiter->task); raw_spin_unlock(&current->pi_lock); }

Contributors

PersonTokensPropCommitsCommitProp
Lai Jiangshan2227.16%112.50%
Ingo Molnar2024.69%112.50%
Peter Zijlstra1619.75%225.00%
Thomas Gleixner1012.35%225.00%
Davidlohr Bueso A911.11%112.50%
Xunlei Pang44.94%112.50%
Total81100.00%8100.00%

/* * Remove a waiter from a lock and give up * * Must be called with lock->wait_lock held and interrupts disabled. I must * have just failed to try_to_take_rt_mutex(). */
static void remove_waiter(struct rt_mutex *lock, struct rt_mutex_waiter *waiter) { bool is_top_waiter = (waiter == rt_mutex_top_waiter(lock)); struct task_struct *owner = rt_mutex_owner(lock); struct rt_mutex *next_lock; lockdep_assert_held(&lock->wait_lock); raw_spin_lock(&current->pi_lock); rt_mutex_dequeue(lock, waiter); current->pi_blocked_on = NULL; raw_spin_unlock(&current->pi_lock); /* * Only update priority if the waiter was the highest priority * waiter of the lock and there is an owner to update. */ if (!owner || !is_top_waiter) return; raw_spin_lock(&owner->pi_lock); rt_mutex_dequeue_pi(owner, waiter); if (rt_mutex_has_waiters(lock)) rt_mutex_enqueue_pi(owner, rt_mutex_top_waiter(lock)); rt_mutex_adjust_prio(owner); /* Store the lock on which owner is blocked or NULL */ next_lock = task_blocked_on_lock(owner); raw_spin_unlock(&owner->pi_lock); /* * Don't walk the chain, if the owner task is not blocked * itself. */ if (!next_lock) return; /* gets dropped in rt_mutex_adjust_prio_chain()! */ get_task_struct(owner); raw_spin_unlock_irq(&lock->wait_lock); rt_mutex_adjust_prio_chain(owner, RT_MUTEX_MIN_CHAINWALK, lock, next_lock, NULL, current); raw_spin_lock_irq(&lock->wait_lock); }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar12767.91%321.43%
Thomas Gleixner3418.18%642.86%
Peter Zijlstra179.09%321.43%
Steven Rostedt63.21%17.14%
Lai Jiangshan31.60%17.14%
Total187100.00%14100.00%

/* * Recheck the pi chain, in case we got a priority setting * * Called from sched_setscheduler */
void rt_mutex_adjust_pi(struct task_struct *task) { struct rt_mutex_waiter *waiter; struct rt_mutex *next_lock; unsigned long flags; raw_spin_lock_irqsave(&task->pi_lock, flags); waiter = task->pi_blocked_on; if (!waiter || rt_mutex_waiter_equal(waiter, task_to_waiter(task))) { raw_spin_unlock_irqrestore(&task->pi_lock, flags); return; } next_lock = waiter->lock; raw_spin_unlock_irqrestore(&task->pi_lock, flags); /* gets dropped in rt_mutex_adjust_prio_chain()! */ get_task_struct(task); rt_mutex_adjust_prio_chain(task, RT_MUTEX_MIN_CHAINWALK, NULL, next_lock, NULL, task); }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner8782.86%450.00%
Steven Rostedt65.71%112.50%
Peter Zijlstra54.76%112.50%
Ingo Molnar54.76%112.50%
Dario Faggioli21.90%112.50%
Total105100.00%8100.00%


void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter) { debug_rt_mutex_init_waiter(waiter); RB_CLEAR_NODE(&waiter->pi_tree_entry); RB_CLEAR_NODE(&waiter->tree_entry); waiter->task = NULL; }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra37100.00%1100.00%
Total37100.00%1100.00%

/** * __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop * @lock: the rt_mutex to take * @state: the state the task should block in (TASK_INTERRUPTIBLE * or TASK_UNINTERRUPTIBLE) * @timeout: the pre-initialized and started timer, or NULL for none * @waiter: the pre-initialized rt_mutex_waiter * * Must be called with lock->wait_lock held and interrupts disabled */
static int __sched __rt_mutex_slowlock(struct rt_mutex *lock, int state, struct hrtimer_sleeper *timeout, struct rt_mutex_waiter *waiter) { int ret = 0; for (;;) { /* Try to acquire the lock: */ if (try_to_take_rt_mutex(lock, current, waiter)) break; /* * TASK_INTERRUPTIBLE checks for signals and * timeout. Ignored otherwise. */ if (likely(state == TASK_INTERRUPTIBLE)) { /* Signal pending? */ if (signal_pending(current)) ret = -EINTR; if (timeout && !timeout->task) ret = -ETIMEDOUT; if (ret) break; } raw_spin_unlock_irq(&lock->wait_lock); debug_rt_mutex_print_deadlock(waiter); schedule(); raw_spin_lock_irq(&lock->wait_lock); set_current_state(state); } __set_current_state(TASK_RUNNING); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar10882.44%225.00%
Darren Hart96.87%112.50%
Davidlohr Bueso A75.34%225.00%
Lai Jiangshan43.05%112.50%
Thomas Gleixner21.53%112.50%
Steven Rostedt10.76%112.50%
Total131100.00%8100.00%


static void rt_mutex_handle_deadlock(int res, int detect_deadlock, struct rt_mutex_waiter *w) { /* * If the result is not -EDEADLOCK or the caller requested * deadlock detection, nothing to do here. */ if (res != -EDEADLOCK || detect_deadlock) return; /* * Yell lowdly and stop the task right here. */ rt_mutex_print_deadlock(w); while (1) { set_current_state(TASK_INTERRUPTIBLE); schedule(); } }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner48100.00%1100.00%
Total48100.00%1100.00%

/* * Slow path lock function: */
static int __sched rt_mutex_slowlock(struct rt_mutex *lock, int state, struct hrtimer_sleeper *timeout, enum rtmutex_chainwalk chwalk) { struct rt_mutex_waiter waiter; unsigned long flags; int ret = 0; rt_mutex_init_waiter(&waiter); /* * Technically we could use raw_spin_[un]lock_irq() here, but this can * be called in early boot if the cmpxchg() fast path is disabled * (debug, no architecture support). In this case we will acquire the * rtmutex with lock->wait_lock held. But we cannot unconditionally * enable interrupts in that early boot case. So we need to use the * irqsave/restore variants. */ raw_spin_lock_irqsave(&lock->wait_lock, flags); /* Try to acquire the lock again: */ if (try_to_take_rt_mutex(lock, current, NULL)) { raw_spin_unlock_irqrestore(&lock->wait_lock, flags); return 0; } set_current_state(state); /* Setup the timer, when timeout != NULL */ if (unlikely(timeout)) hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS); ret = task_blocks_on_rt_mutex(lock, &waiter, current, chwalk); if (likely(!ret)) /* sleep on the mutex */ ret = __rt_mutex_slowlock(lock, state, timeout, &waiter); if (unlikely(ret)) { __set_current_state(TASK_RUNNING); if (rt_mutex_has_waiters(lock)) remove_waiter(lock, &waiter); rt_mutex_handle_deadlock(ret, chwalk, &waiter); } /* * try_to_take_rt_mutex() sets the waiter bit * unconditionally. We might have to fix that up. */ fixup_rt_mutex_waiters(lock); raw_spin_unlock_irqrestore(&lock->wait_lock, flags); /* Remove pending timer: */ if (unlikely(timeout)) hrtimer_cancel(&timeout->timer); debug_rt_mutex_free_waiter(&waiter); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Darren Hart10949.32%18.33%
Ingo Molnar3716.74%216.67%
Thomas Gleixner3013.57%325.00%
Lai Jiangshan2611.76%18.33%
Sebastian Andrzej Siewior125.43%216.67%
Peter Zijlstra62.71%216.67%
Davidlohr Bueso A10.45%18.33%
Total221100.00%12100.00%


static inline int __rt_mutex_slowtrylock(struct rt_mutex *lock) { int ret = try_to_take_rt_mutex(lock, current, NULL); /* * try_to_take_rt_mutex() sets the lock waiters bit * unconditionally. Clean this up. */ fixup_rt_mutex_waiters(lock); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra33100.00%1100.00%
Total33100.00%1100.00%

/* * Slow path try-lock function: */
static inline int rt_mutex_slowtrylock(struct rt_mutex *lock) { unsigned long flags; int ret; /* * If the lock already has an owner we fail to get the lock. * This can be done without taking the @lock->wait_lock as * it is only being read, and this is a trylock anyway. */ if (rt_mutex_owner(lock)) return 0; /* * The mutex has currently no owner. Lock the wait lock and try to * acquire the lock. We use irqsave here to support early boot calls. */ raw_spin_lock_irqsave(&lock->wait_lock, flags); ret = __rt_mutex_slowtrylock(lock); raw_spin_unlock_irqrestore(&lock->wait_lock, flags); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar3862.30%125.00%
Thomas Gleixner2236.07%250.00%
Peter Zijlstra11.64%125.00%
Total61100.00%4100.00%

/* * Slow path to release a rt-mutex. * * Return whether the current task needs to call rt_mutex_postunlock(). */
static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock, struct wake_q_head *wake_q) { unsigned long flags; /* irqsave required to support early boot calls */ raw_spin_lock_irqsave(&lock->wait_lock, flags); debug_rt_mutex_unlock(lock); /* * We must be careful here if the fast path is enabled. If we * have no waiters queued we cannot set owner to NULL here * because of: * * foo->lock->owner = NULL; * rtmutex_lock(foo->lock); <- fast path * free = atomic_dec_and_test(foo->refcnt); * rtmutex_unlock(foo->lock); <- fast path * if (free) * kfree(foo); * raw_spin_unlock(foo->lock->wait_lock); * * So for the fastpath enabled kernel: * * Nothing can set the waiters bit as long as we hold * lock->wait_lock. So we do the following sequence: * * owner = rt_mutex_owner(lock); * clear_rt_mutex_waiters(lock); * raw_spin_unlock(&lock->wait_lock); * if (cmpxchg(&lock->owner, owner, 0) == owner) * return; * goto retry; * * The fastpath disabled variant is simple as all access to * lock->owner is serialized by lock->wait_lock: * * lock->owner = NULL; * raw_spin_unlock(&lock->wait_lock); */ while (!rt_mutex_has_waiters(lock)) { /* Drops lock->wait_lock ! */ if (unlock_rt_mutex_safe(lock, flags) == true) return false; /* Relock the rtmutex and try again */ raw_spin_lock_irqsave(&lock->wait_lock, flags); } /* * The wakeup next waiter path does not suffer from the above * race. See the comments there. * * Queue the next waiter for wakeup once we release the wait_lock. */ mark_wakeup_next_waiter(wake_q, lock); raw_spin_unlock_irqrestore(&lock->wait_lock, flags); return true; /* call rt_mutex_postunlock() */ }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar5153.12%116.67%
Thomas Gleixner2829.17%233.33%
Sebastian Andrzej Siewior1212.50%116.67%
Davidlohr Bueso A44.17%116.67%
Peter Zijlstra11.04%116.67%
Total96100.00%6100.00%

/* * debug aware fast / slowpath lock,trylock,unlock * * The atomic acquire/release ops are compiled away, when either the * architecture does not support cmpxchg or when debugging is enabled. */
static inline int rt_mutex_fastlock(struct rt_mutex *lock, int state, int (*slowfn)(struct rt_mutex *lock, int state, struct hrtimer_sleeper *timeout, enum rtmutex_chainwalk chwalk)) { if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current))) return 0; return slowfn(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK); }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar6392.65%250.00%
Thomas Gleixner45.88%125.00%
Davidlohr Bueso A11.47%125.00%
Total68100.00%4100.00%


static inline int rt_mutex_timed_fastlock(struct rt_mutex *lock, int state, struct hrtimer_sleeper *timeout, enum rtmutex_chainwalk chwalk, int (*slowfn)(struct rt_mutex *lock, int state, struct hrtimer_sleeper *timeout, enum rtmutex_chainwalk chwalk)) { if (chwalk == RT_MUTEX_MIN_CHAINWALK && likely(rt_mutex_cmpxchg_acquire(lock, NULL, current))) return 0; return slowfn(lock, state, timeout, chwalk); }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar7086.42%250.00%
Thomas Gleixner1012.35%125.00%
Davidlohr Bueso A11.23%125.00%
Total81100.00%4100.00%


static inline int rt_mutex_fasttrylock(struct rt_mutex *lock, int (*slowfn)(struct rt_mutex *lock)) { if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current))) return 1; return slowfn(lock); }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar4697.87%266.67%
Davidlohr Bueso A12.13%133.33%
Total47100.00%3100.00%

/* * Performs the wakeup of the the top-waiter and re-enables preemption. */
void rt_mutex_postunlock(struct wake_q_head *wake_q) { wake_up_q(wake_q); /* Pairs with preempt_disable() in rt_mutex_slowunlock() */ preempt_enable(); }

Contributors

PersonTokensPropCommitsCommitProp
Xunlei Pang19100.00%1100.00%
Total19100.00%1100.00%


static inline void rt_mutex_fastunlock(struct rt_mutex *lock, bool (*slowfn)(struct rt_mutex *lock, struct wake_q_head *wqh)) { DEFINE_WAKE_Q(wake_q); if (likely(rt_mutex_cmpxchg_release(lock, current, NULL))) return; if (slowfn(lock, &wake_q)) rt_mutex_postunlock(&wake_q); }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar4163.08%114.29%
Sebastian Andrzej Siewior1726.15%114.29%
Peter Zijlstra46.15%228.57%
Davidlohr Bueso A11.54%114.29%
Waiman Long11.54%114.29%
Xunlei Pang11.54%114.29%
Total65100.00%7100.00%

/** * rt_mutex_lock - lock a rt_mutex * * @lock: the rt_mutex to be locked */
void __sched rt_mutex_lock(struct rt_mutex *lock) { might_sleep(); mutex_acquire(&lock->dep_map, 0, 0, _RET_IP_); rt_mutex_fastlock(lock, TASK_UNINTERRUPTIBLE, rt_mutex_slowlock); }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar2362.16%150.00%
Peter Zijlstra1437.84%150.00%
Total37100.00%2100.00%

EXPORT_SYMBOL_GPL(rt_mutex_lock); /** * rt_mutex_lock_interruptible - lock a rt_mutex interruptible * * @lock: the rt_mutex to be locked * * Returns: * 0 on success * -EINTR when interrupted by a signal */
int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock) { int ret; might_sleep(); mutex_acquire(&lock->dep_map, 0, 0, _RET_IP_); ret = rt_mutex_fastlock(lock, TASK_INTERRUPTIBLE, rt_mutex_slowlock); if (ret) mutex_release(&lock->dep_map, 1, _RET_IP_); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra3862.30%150.00%
Ingo Molnar2337.70%150.00%
Total61100.00%2100.00%

EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible); /* * Futex variant, must not use fastpath. */
int __sched rt_mutex_futex_trylock(struct rt_mutex *lock) { return rt_mutex_slowtrylock(lock); }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra1482.35%150.00%
Thomas Gleixner317.65%150.00%
Total17100.00%2100.00%


int __sched __rt_mutex_futex_trylock(struct rt_mutex *lock) { return __rt_mutex_slowtrylock(lock); }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra17100.00%1100.00%
Total17100.00%1100.00%

/** * rt_mutex_timed_lock - lock a rt_mutex interruptible * the timeout structure is provided * by the caller * * @lock: the rt_mutex to be locked * @timeout: timeout structure or NULL (no timeout) * * Returns: * 0 on success * -EINTR when interrupted by a signal * -ETIMEDOUT when the timeout expired */
int rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout) { int ret; might_sleep(); mutex_acquire(&lock->dep_map, 0, 0, _RET_IP_); ret = rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout, RT_MUTEX_MIN_CHAINWALK, rt_mutex_slowlock); if (ret) mutex_release(&lock->dep_map, 1, _RET_IP_); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra3855.07%133.33%
Ingo Molnar3043.48%133.33%
Thomas Gleixner11.45%133.33%
Total69100.00%3100.00%

EXPORT_SYMBOL_GPL(rt_mutex_timed_lock); /** * rt_mutex_trylock - try to lock a rt_mutex * * @lock: the rt_mutex to be locked * * This function can only be called in thread context. It's safe to * call it from atomic regions, but not from hard interrupt or soft * interrupt context. * * Returns 1 on success and 0 on contention */
int __sched rt_mutex_trylock(struct rt_mutex *lock) { int ret; if (WARN_ON_ONCE(in_irq() || in_nmi() || in_serving_softirq())) return 0; ret = rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock); if (ret) mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra2642.62%125.00%
Ingo Molnar1829.51%125.00%
Thomas Gleixner1626.23%125.00%
Sebastian Andrzej Siewior11.64%125.00%
Total61100.00%4100.00%

EXPORT_SYMBOL_GPL(rt_mutex_trylock); /** * rt_mutex_unlock - unlock a rt_mutex * * @lock: the rt_mutex to be unlocked */
void __sched rt_mutex_unlock(struct rt_mutex *lock) { mutex_release(&lock->dep_map, 1, _RET_IP_); rt_mutex_fastunlock(lock, rt_mutex_slowunlock); }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar1860.00%150.00%
Peter Zijlstra1240.00%150.00%
Total30100.00%2100.00%

EXPORT_SYMBOL_GPL(rt_mutex_unlock); /** * Futex variant, that since futex variants do not use the fast-path, can be * simple and will not need to retry. */
bool __sched __rt_mutex_futex_unlock(struct rt_mutex *lock, struct wake_q_head *wake_q) { lockdep_assert_held(&lock->wait_lock); debug_rt_mutex_unlock(lock); if (!rt_mutex_has_waiters(lock)) { lock->owner = NULL; return false; /* done */ } /* * We've already deboosted, mark_wakeup_next_waiter() will * retain preempt_disabled when we drop the wait_lock, to * avoid inversion prior to the wakeup. preempt_disable() * therein pairs with rt_mutex_postunlock(). */ mark_wakeup_next_waiter(wake_q, lock); return true; /* call postunlock() */ }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra3760.66%250.00%
Sebastian Andrzej Siewior2337.70%125.00%
Mike Galbraith11.64%125.00%
Total61100.00%4100.00%


void __sched rt_mutex_futex_unlock(struct rt_mutex *lock) { DEFINE_WAKE_Q(wake_q); bool postunlock; raw_spin_lock_irq(&lock->wait_lock); postunlock = __rt_mutex_futex_unlock(lock, &wake_q); raw_spin_unlock_irq(&lock->wait_lock); if (postunlock) rt_mutex_postunlock(&wake_q); }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra4989.09%250.00%
Sebastian Andrzej Siewior59.09%125.00%
Xunlei Pang11.82%125.00%
Total55100.00%4100.00%

/** * rt_mutex_destroy - mark a mutex unusable * @lock: the mutex to be destroyed * * This function marks the mutex uninitialized, and any subsequent * use of the mutex is forbidden. The mutex must not be locked when * this function is called. */
void rt_mutex_destroy(struct rt_mutex *lock) { WARN_ON(rt_mutex_is_locked(lock)); #ifdef CONFIG_DEBUG_RT_MUTEXES lock->magic = NULL; #endif }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar29100.00%1100.00%
Total29100.00%1100.00%

EXPORT_SYMBOL_GPL(rt_mutex_destroy); /** * __rt_mutex_init - initialize the rt lock * * @lock: the rt lock to be initialized * * Initialize the rt lock to unlocked state. * * Initializing of a locked rt lock is not allowed */
void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key) { lock->owner = NULL; raw_spin_lock_init(&lock->wait_lock); lock->waiters = RB_ROOT_CACHED; if (name && key) debug_rt_mutex_init(lock, name, key); }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar3869.09%116.67%
Peter Zijlstra916.36%233.33%
Alexander (Sasha) Levin610.91%116.67%
Davidlohr Bueso A11.82%116.67%
Thomas Gleixner11.82%116.67%
Total55100.00%6100.00%

EXPORT_SYMBOL_GPL(__rt_mutex_init); /** * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a * proxy owner * * @lock: the rt_mutex to be locked * @proxy_owner:the task to set as owner * * No locking. Caller has to do serializing itself * * Special API call for PI-futex support. This initializes the rtmutex and * assigns it to @proxy_owner. Concurrent operations on the rtmutex are not * possible at this point because the pi_state which contains the rtmutex * is not yet visible to other tasks. */
void rt_mutex_init_proxy_locked(struct rt_mutex *lock, struct task_struct *proxy_owner) { __rt_mutex_init(lock, NULL, NULL); debug_rt_mutex_proxy_lock(lock, proxy_owner); rt_mutex_set_owner(lock, proxy_owner); }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar3694.74%266.67%
Peter Zijlstra25.26%133.33%
Total38100.00%3100.00%

/** * rt_mutex_proxy_unlock - release a lock on behalf of owner * * @lock: the rt_mutex to be locked * * No locking. Caller has to do serializing itself * * Special API call for PI-futex support. This merrily cleans up the rtmutex * (debugging) state. Concurrent operations on this rt_mutex are not * possible because it belongs to the pi_state which is about to be freed * and it is not longer visible to other tasks. */
void rt_mutex_proxy_unlock(struct rt_mutex *lock, struct task_struct *proxy_owner) { debug_rt_mutex_proxy_unlock(lock); rt_mutex_set_owner(lock, NULL); }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar27100.00%1100.00%
Total27100.00%1100.00%


int __rt_mutex_start_proxy_lock(struct rt_mutex *lock, struct rt_mutex_waiter *waiter, struct task_struct *task) { int ret; if (try_to_take_rt_mutex(lock, task, NULL)) return 1; /* We enforce deadlock detection for futexes */ ret = task_blocks_on_rt_mutex(lock, waiter, task, RT_MUTEX_FULL_CHAINWALK); if (ret && !rt_mutex_owner(lock)) { /* * Reset the return value. We might have * returned with -EDEADLK and the owner * released the lock while we were walking the * pi chain. Let the waiter sort it out. */ ret = 0; } if (unlikely(ret)) remove_waiter(lock, waiter); debug_rt_mutex_print_deadlock(waiter); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Darren Hart5763.33%120.00%
Lai Jiangshan2123.33%120.00%
Peter Zijlstra1011.11%120.00%
Thomas Gleixner22.22%240.00%
Total90100.00%5100.00%

/** * rt_mutex_start_proxy_lock() - Start lock acquisition for another task * @lock: the rt_mutex to take * @waiter: the pre-initialized rt_mutex_waiter * @task: the task to prepare * * Returns: * 0 - task blocked on lock * 1 - acquired the lock for task, caller should wake it up * <0 - error * * Special API call for FUTEX_REQUEUE_PI support. */
int rt_mutex_start_proxy_lock(struct rt_mutex *lock, struct rt_mutex_waiter *waiter, struct task_struct *task) { int ret; raw_spin_lock_irq(&lock->wait_lock); ret = __rt_mutex_start_proxy_lock(lock, waiter, task); raw_spin_unlock_irq(&lock->wait_lock); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra3871.70%150.00%
Darren Hart1528.30%150.00%
Total53100.00%2100.00%

/** * rt_mutex_next_owner - return the next owner of the lock * * @lock: the rt lock query * * Returns the next owner of the lock or NULL * * Caller has to serialize against other accessors to the lock * itself. * * Special API call for PI-futex support */
struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock) { if (!rt_mutex_has_waiters(lock)) return NULL; return rt_mutex_top_waiter(lock)->task; }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar31100.00%1100.00%
Total31100.00%1100.00%

/** * rt_mutex_wait_proxy_lock() - Wait for lock acquisition * @lock: the rt_mutex we were woken on * @to: the timeout, null if none. hrtimer should already have * been started. * @waiter: the pre-initialized rt_mutex_waiter * * Wait for the the lock acquisition started on our behalf by * rt_mutex_start_proxy_lock(). Upon failure, the caller must call * rt_mutex_cleanup_proxy_lock(). * * Returns: * 0 - success * <0 - error, one of -EINTR, -ETIMEDOUT * * Special API call for PI-futex support */
int rt_mutex_wait_proxy_lock(struct rt_mutex *lock, struct hrtimer_sleeper *to, struct rt_mutex_waiter *waiter) { int ret; raw_spin_lock_irq(&lock->wait_lock); /* sleep on the mutex */ set_current_state(TASK_INTERRUPTIBLE); ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter); /* * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might * have to fix that up. */ fixup_rt_mutex_waiters(lock); raw_spin_unlock_irq(&lock->wait_lock); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Darren Hart4668.66%125.00%
Peter Zijlstra2029.85%250.00%
Thomas Gleixner11.49%125.00%
Total67100.00%4100.00%

/** * rt_mutex_cleanup_proxy_lock() - Cleanup failed lock acquisition * @lock: the rt_mutex we were woken on * @waiter: the pre-initialized rt_mutex_waiter * * Attempt to clean up after a failed rt_mutex_wait_proxy_lock(). * * Unless we acquired the lock; we're still enqueued on the wait-list and can * in fact still be granted ownership until we're removed. Therefore we can * find we are in fact the owner and must disregard the * rt_mutex_wait_proxy_lock() failure. * * Returns: * true - did the cleanup, we done. * false - we acquired the lock after rt_mutex_wait_proxy_lock() returned, * caller should disregards its return value. * * Special API call for PI-futex support */
bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock, struct rt_mutex_waiter *waiter) { bool cleanup = false; raw_spin_lock_irq(&lock->wait_lock); /* * Do an unconditional try-lock, this deals with the lock stealing * state where __rt_mutex_futex_unlock() -> mark_wakeup_next_waiter() * sets a NULL owner. * * We're not interested in the return value, because the subsequent * test on rt_mutex_owner() will infer that. If the trylock succeeded, * we will own the lock and it will have removed the waiter. If we * failed the trylock, we're still not owner and we need to remove * ourselves. */ try_to_take_rt_mutex(lock, current, waiter); /* * Unless we're the owner; we're still enqueued on the wait_list. * So check if we became owner, if not, take us off the wait_list. */ if (rt_mutex_owner(lock) != current) { remove_waiter(lock, waiter); cleanup = true; } /* * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might * have to fix that up. */ fixup_rt_mutex_waiters(lock); raw_spin_unlock_irq(&lock->wait_lock); return cleanup; }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra5570.51%360.00%
Darren Hart2228.21%120.00%
Thomas Gleixner11.28%120.00%
Total78100.00%5100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar165937.56%79.46%
Peter Zijlstra107924.43%1418.92%
Thomas Gleixner97622.10%2432.43%
Darren Hart2766.25%11.35%
Lai Jiangshan1513.42%11.35%
Davidlohr Bueso A1022.31%79.46%
Sebastian Andrzej Siewior731.65%56.76%
Xunlei Pang410.93%34.05%
Steven Rostedt280.63%22.70%
Dario Faggioli110.25%11.35%
Alexander (Sasha) Levin60.14%11.35%
Juri Lelli40.09%11.35%
Clark Williams30.07%11.35%
Pavel Emelyanov30.07%11.35%
Luis Henriques10.02%11.35%
Paul Gortmaker10.02%11.35%
Tom (JeHyeon) Yeon10.02%11.35%
Waiman Long10.02%11.35%
Mike Galbraith10.02%11.35%
Total4417100.00%74100.00%
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