From 01768b42dc97a67b4fb33a2535c49fc1969880df Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 31 Oct 2013 18:11:53 +0100 Subject: locking: Move the mutex code to kernel/locking/ Suggested-by: Ingo Molnar Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-1ditvncg30dgbpvrz2bxfmke@git.kernel.org Signed-off-by: Ingo Molnar --- kernel/mutex.c | 960 --------------------------------------------------------- 1 file changed, 960 deletions(-) delete mode 100644 kernel/mutex.c (limited to 'kernel/mutex.c') diff --git a/kernel/mutex.c b/kernel/mutex.c deleted file mode 100644 index d24105b1b794..000000000000 --- a/kernel/mutex.c +++ /dev/null @@ -1,960 +0,0 @@ -/* - * kernel/mutex.c - * - * Mutexes: blocking mutual exclusion locks - * - * Started by Ingo Molnar: - * - * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar - * - * 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 -#include -#include -#include -#include -#include -#include -#include - -/* - * 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 -#else -# include "mutex.h" -# include -#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) -{ - struct task_struct *owner; - int retval = 1; - - rcu_read_lock(); - owner = ACCESS_ONCE(lock->owner); - if (owner) - retval = 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); - -/** - * ww_mutex_unlock - release the w/w mutex - * @lock: the mutex to be released - * - * Unlock a mutex that has been locked by this task previously with any of the - * ww_mutex_lock* functions (with or without an acquire context). It is - * forbidden to release the locks after releasing the acquire context. - * - * This function must not be used in interrupt context. Unlocking - * of a unlocked mutex is not allowed. - */ -void __sched ww_mutex_unlock(struct ww_mutex *lock) -{ - /* - * The unlocking fastpath is the 0->1 transition from 'locked' - * into 'unlocked' state: - */ - if (lock->ctx) { -#ifdef CONFIG_DEBUG_MUTEXES - DEBUG_LOCKS_WARN_ON(!lock->ctx->acquired); -#endif - if (lock->ctx->acquired > 0) - lock->ctx->acquired--; - lock->ctx = NULL; - } - -#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->base); -#endif - __mutex_fastpath_unlock(&lock->base.count, __mutex_unlock_slowpath); -} -EXPORT_SYMBOL(ww_mutex_unlock); - -static inline int __sched -__mutex_lock_check_stamp(struct mutex *lock, struct ww_acquire_ctx *ctx) -{ - struct ww_mutex *ww = container_of(lock, struct ww_mutex, base); - struct ww_acquire_ctx *hold_ctx = ACCESS_ONCE(ww->ctx); - - if (!hold_ctx) - return 0; - - if (unlikely(ctx == hold_ctx)) - return -EALREADY; - - if (ctx->stamp - hold_ctx->stamp <= LONG_MAX && - (ctx->stamp != hold_ctx->stamp || ctx > hold_ctx)) { -#ifdef CONFIG_DEBUG_MUTEXES - DEBUG_LOCKS_WARN_ON(ctx->contending_lock); - ctx->contending_lock = ww; -#endif - return -EDEADLK; - } - - return 0; -} - -static __always_inline void ww_mutex_lock_acquired(struct ww_mutex *ww, - struct ww_acquire_ctx *ww_ctx) -{ -#ifdef CONFIG_DEBUG_MUTEXES - /* - * If this WARN_ON triggers, you used ww_mutex_lock to acquire, - * but released with a normal mutex_unlock in this call. - * - * This should never happen, always use ww_mutex_unlock. - */ - DEBUG_LOCKS_WARN_ON(ww->ctx); - - /* - * Not quite done after calling ww_acquire_done() ? - */ - DEBUG_LOCKS_WARN_ON(ww_ctx->done_acquire); - - if (ww_ctx->contending_lock) { - /* - * After -EDEADLK you tried to - * acquire a different ww_mutex? Bad! - */ - DEBUG_LOCKS_WARN_ON(ww_ctx->contending_lock != ww); - - /* - * You called ww_mutex_lock after receiving -EDEADLK, - * but 'forgot' to unlock everything else first? - */ - DEBUG_LOCKS_WARN_ON(ww_ctx->acquired > 0); - ww_ctx->contending_lock = NULL; - } - - /* - * Naughty, using a different class will lead to undefined behavior! - */ - DEBUG_LOCKS_WARN_ON(ww_ctx->ww_class != ww->ww_class); -#endif - ww_ctx->acquired++; -} - -/* - * after acquiring lock with fastpath or when we lost out in contested - * slowpath, set ctx and wake up any waiters so they can recheck. - * - * This function is never called when CONFIG_DEBUG_LOCK_ALLOC is set, - * as the fastpath and opportunistic spinning are disabled in that case. - */ -static __always_inline void -ww_mutex_set_context_fastpath(struct ww_mutex *lock, - struct ww_acquire_ctx *ctx) -{ - unsigned long flags; - struct mutex_waiter *cur; - - ww_mutex_lock_acquired(lock, ctx); - - lock->ctx = ctx; - - /* - * The lock->ctx update should be visible on all cores before - * the atomic read is done, otherwise contended waiters might be - * missed. The contended waiters will either see ww_ctx == NULL - * and keep spinning, or it will acquire wait_lock, add itself - * to waiter list and sleep. - */ - smp_mb(); /* ^^^ */ - - /* - * Check if lock is contended, if not there is nobody to wake up - */ - if (likely(atomic_read(&lock->base.count) == 0)) - return; - - /* - * Uh oh, we raced in fastpath, wake up everyone in this case, - * so they can see the new lock->ctx. - */ - spin_lock_mutex(&lock->base.wait_lock, flags); - list_for_each_entry(cur, &lock->base.wait_list, list) { - debug_mutex_wake_waiter(&lock->base, cur); - wake_up_process(cur->task); - } - spin_unlock_mutex(&lock->base.wait_lock, flags); -} - -/* - * Lock a mutex (possibly interruptible), slowpath: - */ -static __always_inline int __sched -__mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, - struct lockdep_map *nest_lock, unsigned long ip, - struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx) -{ - struct task_struct *task = current; - struct mutex_waiter waiter; - unsigned long flags; - int ret; - - 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 (use_ww_ctx && ww_ctx->acquired > 0) { - struct ww_mutex *ww; - - ww = container_of(lock, struct ww_mutex, base); - /* - * If ww->ctx is set the contents are undefined, only - * by acquiring wait_lock there is a guarantee that - * they are not invalid when reading. - * - * As such, when deadlock detection needs to be - * performed the optimistic spinning cannot be done. - */ - if (ACCESS_ONCE(ww->ctx)) - goto slowpath; - } - - /* - * 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); - goto slowpath; - } - - if ((atomic_read(&lock->count) == 1) && - (atomic_cmpxchg(&lock->count, 1, 0) == 1)) { - lock_acquired(&lock->dep_map, ip); - if (use_ww_ctx) { - struct ww_mutex *ww; - ww = container_of(lock, struct ww_mutex, base); - - ww_mutex_set_context_fastpath(ww, ww_ctx); - } - - 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))) - goto slowpath; - - /* - * 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); - - /* once more, can we acquire the lock? */ - if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, 0) == 1)) - goto skip_wait; - - 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; - - 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))) { - ret = -EINTR; - goto err; - } - - if (use_ww_ctx && ww_ctx->acquired > 0) { - ret = __mutex_lock_check_stamp(lock, ww_ctx); - if (ret) - goto err; - } - - __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); - } - mutex_remove_waiter(lock, &waiter, current_thread_info()); - /* set it to 0 if there are no waiters left: */ - if (likely(list_empty(&lock->wait_list))) - atomic_set(&lock->count, 0); - debug_mutex_free_waiter(&waiter); - -skip_wait: - /* got the lock - cleanup and rejoice! */ - lock_acquired(&lock->dep_map, ip); - mutex_set_owner(lock); - - if (use_ww_ctx) { - struct ww_mutex *ww = container_of(lock, struct ww_mutex, base); - struct mutex_waiter *cur; - - /* - * This branch gets optimized out for the common case, - * and is only important for ww_mutex_lock. - */ - ww_mutex_lock_acquired(ww, ww_ctx); - ww->ctx = ww_ctx; - - /* - * Give any possible sleeping processes the chance to wake up, - * so they can recheck if they have to back off. - */ - list_for_each_entry(cur, &lock->wait_list, list) { - debug_mutex_wake_waiter(lock, cur); - wake_up_process(cur->task); - } - } - - spin_unlock_mutex(&lock->wait_lock, flags); - preempt_enable(); - return 0; - -err: - mutex_remove_waiter(lock, &waiter, task_thread_info(task)); - spin_unlock_mutex(&lock->wait_lock, flags); - debug_mutex_free_waiter(&waiter); - mutex_release(&lock->dep_map, 1, ip); - preempt_enable(); - return ret; -} - -#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_, NULL, 0); -} - -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_, NULL, 0); -} - -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_, NULL, 0); -} -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_, NULL, 0); -} - -EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested); - -static inline int -ww_mutex_deadlock_injection(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) -{ -#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH - unsigned tmp; - - if (ctx->deadlock_inject_countdown-- == 0) { - tmp = ctx->deadlock_inject_interval; - if (tmp > UINT_MAX/4) - tmp = UINT_MAX; - else - tmp = tmp*2 + tmp + tmp/2; - - ctx->deadlock_inject_interval = tmp; - ctx->deadlock_inject_countdown = tmp; - ctx->contending_lock = lock; - - ww_mutex_unlock(lock); - - return -EDEADLK; - } -#endif - - return 0; -} - -int __sched -__ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) -{ - int ret; - - might_sleep(); - ret = __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE, - 0, &ctx->dep_map, _RET_IP_, ctx, 1); - if (!ret && ctx->acquired > 1) - return ww_mutex_deadlock_injection(lock, ctx); - - return ret; -} -EXPORT_SYMBOL_GPL(__ww_mutex_lock); - -int __sched -__ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) -{ - int ret; - - might_sleep(); - ret = __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE, - 0, &ctx->dep_map, _RET_IP_, ctx, 1); - - if (!ret && ctx->acquired > 1) - return ww_mutex_deadlock_injection(lock, ctx); - - return ret; -} -EXPORT_SYMBOL_GPL(__ww_mutex_lock_interruptible); - -#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(struct mutex *lock); - -static noinline int __sched -__mutex_lock_interruptible_slowpath(struct mutex *lock); - -/** - * mutex_lock_interruptible - acquire the mutex, interruptible - * @lock: the mutex to be acquired - * - * Lock the mutex like mutex_lock(), and return 0 if the mutex has - * been acquired or sleep until the mutex becomes available. If a - * signal arrives while waiting for the lock then this function - * returns -EINTR. - * - * This function is similar to (but not equivalent to) down_interruptible(). - */ -int __sched mutex_lock_interruptible(struct mutex *lock) -{ - int ret; - - might_sleep(); - ret = __mutex_fastpath_lock_retval(&lock->count); - if (likely(!ret)) { - mutex_set_owner(lock); - return 0; - } else - return __mutex_lock_interruptible_slowpath(lock); -} - -EXPORT_SYMBOL(mutex_lock_interruptible); - -int __sched mutex_lock_killable(struct mutex *lock) -{ - int ret; - - might_sleep(); - ret = __mutex_fastpath_lock_retval(&lock->count); - if (likely(!ret)) { - mutex_set_owner(lock); - return 0; - } else - return __mutex_lock_killable_slowpath(lock); -} -EXPORT_SYMBOL(mutex_lock_killable); - -static __used noinline void __sched -__mutex_lock_slowpath(atomic_t *lock_count) -{ - struct mutex *lock = container_of(lock_count, struct mutex, count); - - __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, - NULL, _RET_IP_, NULL, 0); -} - -static noinline int __sched -__mutex_lock_killable_slowpath(struct mutex *lock) -{ - return __mutex_lock_common(lock, TASK_KILLABLE, 0, - NULL, _RET_IP_, NULL, 0); -} - -static noinline int __sched -__mutex_lock_interruptible_slowpath(struct mutex *lock) -{ - return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, - NULL, _RET_IP_, NULL, 0); -} - -static noinline int __sched -__ww_mutex_lock_slowpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) -{ - return __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE, 0, - NULL, _RET_IP_, ctx, 1); -} - -static noinline int __sched -__ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock, - struct ww_acquire_ctx *ctx) -{ - return __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE, 0, - NULL, _RET_IP_, ctx, 1); -} - -#endif - -/* - * Spinlock based trylock, we take the spinlock and check whether we - * can get the lock: - */ -static inline int __mutex_trylock_slowpath(atomic_t *lock_count) -{ - struct mutex *lock = container_of(lock_count, struct mutex, count); - unsigned long flags; - int prev; - - spin_lock_mutex(&lock->wait_lock, flags); - - prev = atomic_xchg(&lock->count, -1); - if (likely(prev == 1)) { - mutex_set_owner(lock); - mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_); - } - - /* Set it back to 0 if there are no waiters: */ - if (likely(list_empty(&lock->wait_list))) - atomic_set(&lock->count, 0); - - spin_unlock_mutex(&lock->wait_lock, flags); - - return prev == 1; -} - -/** - * mutex_trylock - try to acquire the mutex, without waiting - * @lock: the mutex to be acquired - * - * Try to acquire the mutex atomically. Returns 1 if the mutex - * has been acquired successfully, and 0 on contention. - * - * NOTE: this function follows the spin_trylock() convention, so - * it is negated from the down_trylock() return values! Be careful - * about this when converting semaphore users to mutexes. - * - * This function must not be used in interrupt context. The - * mutex must be released by the same task that acquired it. - */ -int __sched mutex_trylock(struct mutex *lock) -{ - int ret; - - ret = __mutex_fastpath_trylock(&lock->count, __mutex_trylock_slowpath); - if (ret) - mutex_set_owner(lock); - - return ret; -} -EXPORT_SYMBOL(mutex_trylock); - -#ifndef CONFIG_DEBUG_LOCK_ALLOC -int __sched -__ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) -{ - int ret; - - might_sleep(); - - ret = __mutex_fastpath_lock_retval(&lock->base.count); - - if (likely(!ret)) { - ww_mutex_set_context_fastpath(lock, ctx); - mutex_set_owner(&lock->base); - } else - ret = __ww_mutex_lock_slowpath(lock, ctx); - return ret; -} -EXPORT_SYMBOL(__ww_mutex_lock); - -int __sched -__ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) -{ - int ret; - - might_sleep(); - - ret = __mutex_fastpath_lock_retval(&lock->base.count); - - if (likely(!ret)) { - ww_mutex_set_context_fastpath(lock, ctx); - mutex_set_owner(&lock->base); - } else - ret = __ww_mutex_lock_interruptible_slowpath(lock, ctx); - return ret; -} -EXPORT_SYMBOL(__ww_mutex_lock_interruptible); - -#endif - -/** - * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0 - * @cnt: the atomic which we are to dec - * @lock: the mutex to return holding if we dec to 0 - * - * return true and hold lock if we dec to 0, return false otherwise - */ -int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock) -{ - /* dec if we can't possibly hit 0 */ - if (atomic_add_unless(cnt, -1, 1)) - return 0; - /* we might hit 0, so take the lock */ - mutex_lock(lock); - if (!atomic_dec_and_test(cnt)) { - /* when we actually did the dec, we didn't hit 0 */ - mutex_unlock(lock); - return 0; - } - /* we hit 0, and we hold the lock */ - return 1; -} -EXPORT_SYMBOL(atomic_dec_and_mutex_lock); -- cgit v1.2.3