/* * kernel/mutex.c * * Mutexes: blocking mutual exclusion locks * * Started by Ingo Molnar: * * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> * * Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and * David Howells for suggestions and improvements. * * - Adaptive spinning for mutexes by Peter Zijlstra. (Ported to mainline * from the -rt tree, where it was originally implemented for rtmutexes * by Steven Rostedt, based on work by Gregory Haskins, Peter Morreale * and Sven Dietrich. * * Also see Documentation/mutex-design.txt. */#include <linux/mutex.h>#include <linux/sched.h>#include <linux/sched/rt.h>#include <linux/export.h>#include <linux/spinlock.h>#include <linux/interrupt.h>#include <linux/debug_locks.h> /* * In the DEBUG case we are using the "NULL fastpath" for mutexes, * which forces all calls into the slowpath: */#ifdef CONFIG_DEBUG_MUTEXES# include "mutex-debug.h"# include <asm-generic/mutex-null.h>#else# include "mutex.h"# include <asm/mutex.h>#endif /* * A negative mutex count indicates that waiters are sleeping waiting for the * mutex. */#define MUTEX_SHOW_NO_WAITER(mutex) (atomic_read(&(mutex)->count) >= 0) void__mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key){ atomic_set(&lock->count, 1); spin_lock_init(&lock->wait_lock); INIT_LIST_HEAD(&lock->wait_list); mutex_clear_owner(lock);#ifdef CONFIG_MUTEX_SPIN_ON_OWNER lock->spin_mlock = NULL;#endif debug_mutex_init(lock, name, key);} EXPORT_SYMBOL(__mutex_init); #ifndef CONFIG_DEBUG_LOCK_ALLOC/* * We split the mutex lock/unlock logic into separate fastpath and * slowpath functions, to reduce the register pressure on the fastpath. * We also put the fastpath first in the kernel image, to make sure the * branch is predicted by the CPU as default-untaken. */static __used noinline void __sched__mutex_lock_slowpath(atomic_t *lock_count); /** * mutex_lock - acquire the mutex * @lock: the mutex to be acquired * * Lock the mutex exclusively for this task. If the mutex is not * available right now, it will sleep until it can get it. * * The mutex must later on be released by the same task that * acquired it. Recursive locking is not allowed. The task * may not exit without first unlocking the mutex. Also, kernel * memory where the mutex resides mutex must not be freed with * the mutex still locked. The mutex must first be initialized * (or statically defined) before it can be locked. memset()-ing * the mutex to 0 is not allowed. * * ( The CONFIG_DEBUG_MUTEXES .config option turns on debugging * checks that will enforce the restrictions and will also do * deadlock debugging. ) * * This function is similar to (but not equivalent to) down(). */void __sched mutex_lock(struct mutex *lock){ might_sleep(); /* * The locking fastpath is the 1->0 transition from * 'unlocked' into 'locked' state. */ __mutex_fastpath_lock(&lock->count, __mutex_lock_slowpath); mutex_set_owner(lock);} EXPORT_SYMBOL(mutex_lock);#endif #ifdef CONFIG_MUTEX_SPIN_ON_OWNER/* * In order to avoid a stampede of mutex spinners from acquiring the mutex * more or less simultaneously, the spinners need to acquire a MCS lock * first before spinning on the owner field. * * We don't inline mspin_lock() so that perf can correctly account for the * time spent in this lock function. */struct mspin_node { struct mspin_node *next ; int locked; /* 1 if lock acquired */};#define MLOCK(mutex) ((struct mspin_node **)&((mutex)->spin_mlock)) static noinlinevoid mspin_lock(struct mspin_node **lock, struct mspin_node *node){ struct mspin_node *prev; /* Init node */ node->locked = 0; node->next = NULL; prev = xchg(lock, node); if (likely(prev == NULL)) { /* Lock acquired */ node->locked = 1; return; } ACCESS_ONCE(prev->next) = node; smp_wmb(); /* Wait until the lock holder passes the lock down */ while (!ACCESS_ONCE(node->locked)) arch_mutex_cpu_relax();} static void mspin_unlock(struct mspin_node **lock, struct mspin_node *node){ struct mspin_node *next = ACCESS_ONCE(node->next); if (likely(!next)) { /* * Release the lock by setting it to NULL */ if (cmpxchg(lock, node, NULL) == node) return; /* Wait until the next pointer is set */ while (!(next = ACCESS_ONCE(node->next))) arch_mutex_cpu_relax(); } ACCESS_ONCE(next->locked) = 1; smp_wmb();} /* * Mutex spinning code migrated from kernel/sched/core.c */ static inline bool owner_running(struct mutex *lock, struct task_struct *owner){ if (lock->owner != owner) return false; /* * Ensure we emit the owner->on_cpu, dereference _after_ checking * lock->owner still matches owner, if that fails, owner might * point to free()d memory, if it still matches, the rcu_read_lock() * ensures the memory stays valid. */ barrier(); return owner->on_cpu;} /* * Look out! "owner" is an entirely speculative pointer * access and not reliable. */static noinlineint mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner){ rcu_read_lock(); while (owner_running(lock, owner)) { if (need_resched()) break; arch_mutex_cpu_relax(); } rcu_read_unlock(); /* * We break out the loop above on need_resched() and when the * owner changed, which is a sign for heavy contention. Return * success only when lock->owner is NULL. */ return lock->owner == NULL;} /* * Initial check for entering the mutex spinning loop */static inline int mutex_can_spin_on_owner(struct mutex *lock){ int retval = 1; rcu_read_lock(); if (lock->owner) retval = lock->owner->on_cpu; rcu_read_unlock(); /* * if lock->owner is not set, the mutex owner may have just acquired * it and not set the owner yet or the mutex has been released. */ return retval;}#endif static __used noinline void __sched __mutex_unlock_slowpath(atomic_t *lock_count); /** * mutex_unlock - release the mutex * @lock: the mutex to be released * * Unlock a mutex that has been locked by this task previously. * * This function must not be used in interrupt context. Unlocking * of a not locked mutex is not allowed. * * This function is similar to (but not equivalent to) up(). */void __sched mutex_unlock(struct mutex *lock){ /* * The unlocking fastpath is the 0->1 transition from 'locked' * into 'unlocked' state: */#ifndef CONFIG_DEBUG_MUTEXES /* * When debugging is enabled we must not clear the owner before time, * the slow path will always be taken, and that clears the owner field * after verifying that it was indeed current. */ mutex_clear_owner(lock);#endif __mutex_fastpath_unlock(&lock->count, __mutex_unlock_slowpath);} EXPORT_SYMBOL(mutex_unlock); /* * Lock a mutex (possibly interruptible), slowpath: */static inline int __sched__mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, struct lockdep_map *nest_lock, unsigned long ip){ struct task_struct *task = current; struct mutex_waiter waiter; unsigned long flags; preempt_disable(); mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip); #ifdef CONFIG_MUTEX_SPIN_ON_OWNER /* * Optimistic spinning. * * We try to spin for acquisition when we find that there are no * pending waiters and the lock owner is currently running on a * (different) CPU. * * The rationale is that if the lock owner is running, it is likely to * release the lock soon. * * Since this needs the lock owner, and this mutex implementation * doesn't track the owner atomically in the lock field, we need to * track it non-atomically. * * We can't do this for DEBUG_MUTEXES because that relies on wait_lock * to serialize everything. * * The mutex spinners are queued up using MCS lock so that only one * spinner can compete for the mutex. However, if mutex spinning isn't * going to happen, there is no point in going through the lock/unlock * overhead. */ if (!mutex_can_spin_on_owner(lock)) goto slowpath; for (;;) { struct task_struct *owner; struct mspin_node node; /* * If there's an owner, wait for it to either * release the lock or go to sleep. */ mspin_lock(MLOCK(lock), &node); owner = ACCESS_ONCE(lock->owner); if (owner && !mutex_spin_on_owner(lock, owner)) { mspin_unlock(MLOCK(lock), &node); break; } if ((atomic_read(&lock->count) == 1) && (atomic_cmpxchg(&lock->count, 1, 0) == 1)) { lock_acquired(&lock->dep_map, ip); mutex_set_owner(lock); mspin_unlock(MLOCK(lock), &node); preempt_enable(); return 0; } mspin_unlock(MLOCK(lock), &node); /* * When there's no owner, we might have preempted between the * owner acquiring the lock and setting the owner field. If * we're an RT task that will live-lock because we won't let * the owner complete. */ if (!owner && (need_resched() || rt_task(task))) break; /* * The cpu_relax() call is a compiler barrier which forces * everything in this loop to be re-loaded. We don't need * memory barriers as we'll eventually observe the right * values at the cost of a few extra spins. */ arch_mutex_cpu_relax(); }slowpath:#endif spin_lock_mutex(&lock->wait_lock, flags); debug_mutex_lock_common(lock, &waiter); debug_mutex_add_waiter(lock, &waiter, task_thread_info(task)); /* add waiting tasks to the end of the waitqueue (FIFO): */ list_add_tail(&waiter.list, &lock->wait_list); waiter.task = task; if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, -1) == 1)) goto done; lock_contended(&lock->dep_map, ip); for (;;) { /* * Lets try to take the lock again - this is needed even if * we get here for the first time (shortly after failing to * acquire the lock), to make sure that we get a wakeup once * it's unlocked. Later on, if we sleep, this is the * operation that gives us the lock. We xchg it to -1, so * that when we release the lock, we properly wake up the * other waiters: */ if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, -1) == 1)) break; /* * got a signal? (This code gets eliminated in the * TASK_UNINTERRUPTIBLE case.) */ if (unlikely(signal_pending_state(state, task))) { mutex_remove_waiter(lock, &waiter, task_thread_info(task)); mutex_release(&lock->dep_map, 1, ip); spin_unlock_mutex(&lock->wait_lock, flags); debug_mutex_free_waiter(&waiter); preempt_enable(); return -EINTR; } __set_task_state(task, state); /* didn't get the lock, go to sleep: */ spin_unlock_mutex(&lock->wait_lock, flags); schedule_preempt_disabled(); spin_lock_mutex(&lock->wait_lock, flags); } done: lock_acquired(&lock->dep_map, ip); /* got the lock - rejoice! */ mutex_remove_waiter(lock, &waiter, current_thread_info()); mutex_set_owner(lock); /* set it to 0 if there are no waiters left: */ if (likely(list_empty(&lock->wait_list))) atomic_set(&lock->count, 0); spin_unlock_mutex(&lock->wait_lock, flags); debug_mutex_free_waiter(&waiter); preempt_enable(); return 0;} #ifdef CONFIG_DEBUG_LOCK_ALLOCvoid __schedmutex_lock_nested(struct mutex *lock, unsigned int subclass){ might_sleep(); __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);} EXPORT_SYMBOL_GPL(mutex_lock_nested); void __sched_mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest){ might_sleep(); __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, nest, _RET_IP_);} EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock); int __schedmutex_lock_killable_nested(struct mutex *lock, unsigned int subclass){ might_sleep(); return __mutex_lock_common(lock, TASK_KILLABLE, subclass, NULL, _RET_IP_);}EXPORT_SYMBOL_GPL(mutex_lock_killable_nested); int __schedmutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass){ might_sleep(); return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass, NULL, _RET_IP_);} EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);#endif /* * Release the lock, slowpath: */static inline void__mutex_unlock_common_slowpath(atomic_t *lock_count, int nested){ struct mutex *lock = container_of(lock_count, struct mutex, count); unsigned long flags; spin_lock_mutex(&lock->wait_lock, flags); mutex_release(&lock->dep_map, nested, _RET_IP_); debug_mutex_unlock(lock); /* * some architectures leave the lock unlocked in the fastpath failure * case, others need to leave it locked. In the later case we have to * unlock it here */ if (__mutex_slowpath_needs_to_unlock()) atomic_set(&lock->count, 1); if (!list_empty(&lock->wait_list)) { /* get the first entry from the wait-list: */ struct mutex_waiter *waiter = list_entry(lock->wait_list.next, struct mutex_waiter, list); debug_mutex_wake_waiter(lock, waiter); wake_up_process(waiter->task); } spin_unlock_mutex(&lock->wait_lock, flags);} /* * Release the lock, slowpath: */static __used noinline void__mutex_unlock_slowpath(atomic_t *lock_count){ __mutex_unlock_common_slowpath(lock_count, 1);} #ifndef CONFIG_DEBUG_LOCK_ALLOC/* * Here come the less common (and hence less performance-critical) APIs: * mutex_lock_interruptible() and mutex_trylock(). */static noinline int __sched__mutex_lock_killable_slowpath(atomic_t *lock_count); static noinline int __sched__mutex_lock_interruptible_slowpath(atomic_t *lock_count);Lines 1–500 of 642. Load more
/* * kernel/mutex.c * * Mutexes: blocking mutual exclusion locks * * Started by Ingo Molnar: * * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> * * Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and * David Howells for suggestions and improvements. * * - Adaptive spinning for mutexes by Peter Zijlstra. (Ported to mainline * from the -rt tree, where it was originally implemented for rtmutexes * by Steven Rostedt, based on work by Gregory Haskins, Peter Morreale * and Sven Dietrich. * * Also see Documentation/mutex-design.txt. */ #include <linux/mutex.h> #include <linux/sched.h> #include <linux/sched/rt.h> #include <linux/export.h> #include <linux/spinlock.h> #include <linux/interrupt.h> #include <linux/debug_locks.h> /* * In the DEBUG case we are using the "NULL fastpath" for mutexes, * which forces all calls into the slowpath: */ #ifdef CONFIG_DEBUG_MUTEXES # include "mutex-debug.h" # include <asm-generic/mutex-null.h> #else # include "mutex.h" # include <asm/mutex.h> #endif /* * A negative mutex count indicates that waiters are sleeping waiting for the * mutex. */ #define MUTEX_SHOW_NO_WAITER(mutex) (atomic_read(&(mutex)->count) >= 0) void __mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key) { atomic_set(&lock->count, 1); spin_lock_init(&lock->wait_lock); INIT_LIST_HEAD(&lock->wait_list); mutex_clear_owner(lock); #ifdef CONFIG_MUTEX_SPIN_ON_OWNER lock->spin_mlock = NULL; #endif debug_mutex_init(lock, name, key); } EXPORT_SYMBOL(__mutex_init); #ifndef CONFIG_DEBUG_LOCK_ALLOC /* * We split the mutex lock/unlock logic into separate fastpath and * slowpath functions, to reduce the register pressure on the fastpath. * We also put the fastpath first in the kernel image, to make sure the * branch is predicted by the CPU as default-untaken. */ static __used noinline void __sched __mutex_lock_slowpath(atomic_t *lock_count); /** * mutex_lock - acquire the mutex * @lock: the mutex to be acquired * * Lock the mutex exclusively for this task. If the mutex is not * available right now, it will sleep until it can get it. * * The mutex must later on be released by the same task that * acquired it. Recursive locking is not allowed. The task * may not exit without first unlocking the mutex. Also, kernel * memory where the mutex resides mutex must not be freed with * the mutex still locked. The mutex must first be initialized * (or statically defined) before it can be locked. memset()-ing * the mutex to 0 is not allowed. * * ( The CONFIG_DEBUG_MUTEXES .config option turns on debugging * checks that will enforce the restrictions and will also do * deadlock debugging. ) * * This function is similar to (but not equivalent to) down(). */ void __sched mutex_lock(struct mutex *lock) { might_sleep(); /* * The locking fastpath is the 1->0 transition from * 'unlocked' into 'locked' state. */ __mutex_fastpath_lock(&lock->count, __mutex_lock_slowpath); mutex_set_owner(lock); } EXPORT_SYMBOL(mutex_lock); #endif #ifdef CONFIG_MUTEX_SPIN_ON_OWNER /* * In order to avoid a stampede of mutex spinners from acquiring the mutex * more or less simultaneously, the spinners need to acquire a MCS lock * first before spinning on the owner field. * * We don't inline mspin_lock() so that perf can correctly account for the * time spent in this lock function. */ struct mspin_node { struct mspin_node *next ; int locked; /* 1 if lock acquired */ }; #define MLOCK(mutex) ((struct mspin_node **)&((mutex)->spin_mlock)) static noinline void mspin_lock(struct mspin_node **lock, struct mspin_node *node) { struct mspin_node *prev; /* Init node */ node->locked = 0; node->next = NULL; prev = xchg(lock, node); if (likely(prev == NULL)) { /* Lock acquired */ node->locked = 1; return; } ACCESS_ONCE(prev->next) = node; smp_wmb(); /* Wait until the lock holder passes the lock down */ while (!ACCESS_ONCE(node->locked)) arch_mutex_cpu_relax(); } static void mspin_unlock(struct mspin_node **lock, struct mspin_node *node) { struct mspin_node *next = ACCESS_ONCE(node->next); if (likely(!next)) { /* * Release the lock by setting it to NULL */ if (cmpxchg(lock, node, NULL) == node) return; /* Wait until the next pointer is set */ while (!(next = ACCESS_ONCE(node->next))) arch_mutex_cpu_relax(); } ACCESS_ONCE(next->locked) = 1; smp_wmb(); } /* * Mutex spinning code migrated from kernel/sched/core.c */ static inline bool owner_running(struct mutex *lock, struct task_struct *owner) { if (lock->owner != owner) return false; /* * Ensure we emit the owner->on_cpu, dereference _after_ checking * lock->owner still matches owner, if that fails, owner might * point to free()d memory, if it still matches, the rcu_read_lock() * ensures the memory stays valid. */ barrier(); return owner->on_cpu; } /* * Look out! "owner" is an entirely speculative pointer * access and not reliable. */ static noinline int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner) { rcu_read_lock(); while (owner_running(lock, owner)) { if (need_resched()) break; arch_mutex_cpu_relax(); } rcu_read_unlock(); /* * We break out the loop above on need_resched() and when the * owner changed, which is a sign for heavy contention. Return * success only when lock->owner is NULL. */ return lock->owner == NULL; } /* * Initial check for entering the mutex spinning loop */ static inline int mutex_can_spin_on_owner(struct mutex *lock) { int retval = 1; rcu_read_lock(); if (lock->owner) retval = lock->owner->on_cpu; rcu_read_unlock(); /* * if lock->owner is not set, the mutex owner may have just acquired * it and not set the owner yet or the mutex has been released. */ return retval; } #endif static __used noinline void __sched __mutex_unlock_slowpath(atomic_t *lock_count); /** * mutex_unlock - release the mutex * @lock: the mutex to be released * * Unlock a mutex that has been locked by this task previously. * * This function must not be used in interrupt context. Unlocking * of a not locked mutex is not allowed. * * This function is similar to (but not equivalent to) up(). */ void __sched mutex_unlock(struct mutex *lock) { /* * The unlocking fastpath is the 0->1 transition from 'locked' * into 'unlocked' state: */ #ifndef CONFIG_DEBUG_MUTEXES /* * When debugging is enabled we must not clear the owner before time, * the slow path will always be taken, and that clears the owner field * after verifying that it was indeed current. */ mutex_clear_owner(lock); #endif __mutex_fastpath_unlock(&lock->count, __mutex_unlock_slowpath); } EXPORT_SYMBOL(mutex_unlock); /* * Lock a mutex (possibly interruptible), slowpath: */ static inline int __sched __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, struct lockdep_map *nest_lock, unsigned long ip) { struct task_struct *task = current; struct mutex_waiter waiter; unsigned long flags; preempt_disable(); mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip); #ifdef CONFIG_MUTEX_SPIN_ON_OWNER /* * Optimistic spinning. * * We try to spin for acquisition when we find that there are no * pending waiters and the lock owner is currently running on a * (different) CPU. * * The rationale is that if the lock owner is running, it is likely to * release the lock soon. * * Since this needs the lock owner, and this mutex implementation * doesn't track the owner atomically in the lock field, we need to * track it non-atomically. * * We can't do this for DEBUG_MUTEXES because that relies on wait_lock * to serialize everything. * * The mutex spinners are queued up using MCS lock so that only one * spinner can compete for the mutex. However, if mutex spinning isn't * going to happen, there is no point in going through the lock/unlock * overhead. */ if (!mutex_can_spin_on_owner(lock)) goto slowpath; for (;;) { struct task_struct *owner; struct mspin_node node; /* * If there's an owner, wait for it to either * release the lock or go to sleep. */ mspin_lock(MLOCK(lock), &node); owner = ACCESS_ONCE(lock->owner); if (owner && !mutex_spin_on_owner(lock, owner)) { mspin_unlock(MLOCK(lock), &node); break; } if ((atomic_read(&lock->count) == 1) && (atomic_cmpxchg(&lock->count, 1, 0) == 1)) { lock_acquired(&lock->dep_map, ip); mutex_set_owner(lock); mspin_unlock(MLOCK(lock), &node); preempt_enable(); return 0; } mspin_unlock(MLOCK(lock), &node); /* * When there's no owner, we might have preempted between the * owner acquiring the lock and setting the owner field. If * we're an RT task that will live-lock because we won't let * the owner complete. */ if (!owner && (need_resched() || rt_task(task))) break; /* * The cpu_relax() call is a compiler barrier which forces * everything in this loop to be re-loaded. We don't need * memory barriers as we'll eventually observe the right * values at the cost of a few extra spins. */ arch_mutex_cpu_relax(); } slowpath: #endif spin_lock_mutex(&lock->wait_lock, flags); debug_mutex_lock_common(lock, &waiter); debug_mutex_add_waiter(lock, &waiter, task_thread_info(task)); /* add waiting tasks to the end of the waitqueue (FIFO): */ list_add_tail(&waiter.list, &lock->wait_list); waiter.task = task; if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, -1) == 1)) goto done; lock_contended(&lock->dep_map, ip); for (;;) { /* * Lets try to take the lock again - this is needed even if * we get here for the first time (shortly after failing to * acquire the lock), to make sure that we get a wakeup once * it's unlocked. Later on, if we sleep, this is the * operation that gives us the lock. We xchg it to -1, so * that when we release the lock, we properly wake up the * other waiters: */ if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, -1) == 1)) break; /* * got a signal? (This code gets eliminated in the * TASK_UNINTERRUPTIBLE case.) */ if (unlikely(signal_pending_state(state, task))) { mutex_remove_waiter(lock, &waiter, task_thread_info(task)); mutex_release(&lock->dep_map, 1, ip); spin_unlock_mutex(&lock->wait_lock, flags); debug_mutex_free_waiter(&waiter); preempt_enable(); return -EINTR; } __set_task_state(task, state); /* didn't get the lock, go to sleep: */ spin_unlock_mutex(&lock->wait_lock, flags); schedule_preempt_disabled(); spin_lock_mutex(&lock->wait_lock, flags); } done: lock_acquired(&lock->dep_map, ip); /* got the lock - rejoice! */ mutex_remove_waiter(lock, &waiter, current_thread_info()); mutex_set_owner(lock); /* set it to 0 if there are no waiters left: */ if (likely(list_empty(&lock->wait_list))) atomic_set(&lock->count, 0); spin_unlock_mutex(&lock->wait_lock, flags); debug_mutex_free_waiter(&waiter); preempt_enable(); return 0; } #ifdef CONFIG_DEBUG_LOCK_ALLOC void __sched mutex_lock_nested(struct mutex *lock, unsigned int subclass) { might_sleep(); __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_); } EXPORT_SYMBOL_GPL(mutex_lock_nested); void __sched _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest) { might_sleep(); __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, nest, _RET_IP_); } EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock); int __sched mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass) { might_sleep(); return __mutex_lock_common(lock, TASK_KILLABLE, subclass, NULL, _RET_IP_); } EXPORT_SYMBOL_GPL(mutex_lock_killable_nested); int __sched mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass) { might_sleep(); return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass, NULL, _RET_IP_); } EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested); #endif /* * Release the lock, slowpath: */ static inline void __mutex_unlock_common_slowpath(atomic_t *lock_count, int nested) { struct mutex *lock = container_of(lock_count, struct mutex, count); unsigned long flags; spin_lock_mutex(&lock->wait_lock, flags); mutex_release(&lock->dep_map, nested, _RET_IP_); debug_mutex_unlock(lock); /* * some architectures leave the lock unlocked in the fastpath failure * case, others need to leave it locked. In the later case we have to * unlock it here */ if (__mutex_slowpath_needs_to_unlock()) atomic_set(&lock->count, 1); if (!list_empty(&lock->wait_list)) { /* get the first entry from the wait-list: */ struct mutex_waiter *waiter = list_entry(lock->wait_list.next, struct mutex_waiter, list); debug_mutex_wake_waiter(lock, waiter); wake_up_process(waiter->task); } spin_unlock_mutex(&lock->wait_lock, flags); } /* * Release the lock, slowpath: */ static __used noinline void __mutex_unlock_slowpath(atomic_t *lock_count) { __mutex_unlock_common_slowpath(lock_count, 1); } #ifndef CONFIG_DEBUG_LOCK_ALLOC /* * Here come the less common (and hence less performance-critical) APIs: * mutex_lock_interruptible() and mutex_trylock(). */ static noinline int __sched __mutex_lock_killable_slowpath(atomic_t *lock_count); static noinline int __sched __mutex_lock_interruptible_slowpath(atomic_t *lock_count);