// SPDX-License-Identifier: GPL-2.0-only/* * rtmutex API */#include <linux/spinlock.h>#include <linux/export.h> #define RT_MUTEX_BUILD_MUTEX#include "rtmutex.c" /* * Max number of times we'll walk the boosting chain: */int max_lock_depth = 1024; static const struct ctl_table rtmutex_sysctl_table[] = { { .procname = "max_lock_depth", .data = &max_lock_depth, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec, },}; static int __init init_rtmutex_sysctl(void){ register_sysctl_init("kernel", rtmutex_sysctl_table); return 0;} subsys_initcall(init_rtmutex_sysctl); /* * 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 __always_inline int __rt_mutex_lock_common(struct rt_mutex *lock, unsigned int state, struct lockdep_map *nest_lock, unsigned int subclass) __cond_acquires(0, lock){ int ret; might_sleep(); mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, _RET_IP_); ret = __rt_mutex_lock(&lock->rtmutex, state); if (ret) mutex_release(&lock->dep_map, _RET_IP_); return ret;} void rt_mutex_base_init(struct rt_mutex_base *rtb){ __rt_mutex_base_init(rtb);}EXPORT_SYMBOL(rt_mutex_base_init); #ifdef CONFIG_DEBUG_LOCK_ALLOC/** * rt_mutex_lock_nested - lock a rt_mutex * * @lock: the rt_mutex to be locked * @subclass: the lockdep subclass */void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass){ if (__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, subclass) == 0) return; /* * The code below is never reached because __rt_mutex_lock_common() only * returns an error code if interrupted by a signal or upon a timeout. */ WARN_ON_ONCE(true); __acquire(lock);}EXPORT_SYMBOL_GPL(rt_mutex_lock_nested); void __sched _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock){ if (__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, nest_lock, 0) == 0) return; /* * The code below is never reached because __rt_mutex_lock_common() only * returns an error code if interrupted by a signal or upon a timeout. */ WARN_ON_ONCE(true); __acquire(lock);}EXPORT_SYMBOL_GPL(_rt_mutex_lock_nest_lock); #else /* !CONFIG_DEBUG_LOCK_ALLOC */ /** * rt_mutex_lock - lock a rt_mutex * * @lock: the rt_mutex to be locked */void __sched rt_mutex_lock(struct rt_mutex *lock){ if (__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, 0) == 0) return; /* * The code below is never reached because __rt_mutex_lock_common() only * returns an error code if interrupted by a signal or upon a timeout. */ WARN_ON_ONCE(true); __acquire(lock);}EXPORT_SYMBOL_GPL(rt_mutex_lock);#endif /** * 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){ return __rt_mutex_lock_common(lock, TASK_INTERRUPTIBLE, NULL, 0);}EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible); /** * rt_mutex_lock_killable - lock a rt_mutex killable * * @lock: the rt_mutex to be locked * * Returns: * 0 on success * -EINTR when interrupted by a signal */int __sched rt_mutex_lock_killable(struct rt_mutex *lock){ return __rt_mutex_lock_common(lock, TASK_KILLABLE, NULL, 0);}EXPORT_SYMBOL_GPL(rt_mutex_lock_killable); /** * 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 or soft interrupt context. * * Returns: * 1 on success * 0 on contention */int __sched rt_mutex_trylock(struct rt_mutex *lock){ int ret; if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task())) return 0; ret = __rt_mutex_trylock(&lock->rtmutex); if (ret) mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_); return ret;}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, _RET_IP_); __rt_mutex_unlock(&lock->rtmutex); __release(lock);}EXPORT_SYMBOL_GPL(rt_mutex_unlock); /* * Futex variants, must not use fastpath. */int __sched rt_mutex_futex_trylock(struct rt_mutex_base *lock){ return rt_mutex_slowtrylock(lock);} int __sched __rt_mutex_futex_trylock(struct rt_mutex_base *lock){ return __rt_mutex_slowtrylock(lock);} /** * __rt_mutex_futex_unlock - Futex variant, that since futex variants * do not use the fast-path, can be simple and will not need to retry. * * @lock: The rt_mutex to be unlocked * @wqh: The wake queue head from which to get the next lock waiter */bool __sched __rt_mutex_futex_unlock(struct rt_mutex_base *lock, struct rt_wake_q_head *wqh) __must_hold(&lock->wait_lock){ lockdep_assert_held(&lock->wait_lock); debug_rt_mutex_unlock(lock); if (!rt_mutex_has_waiters(lock)) { lock->owner = NULL; return false; /* done */ } /* * mark_wakeup_next_waiter() deboosts and retains preemption * disabled when dropping the wait_lock, to avoid inversion prior * to the wakeup. preempt_disable() therein pairs with the * preempt_enable() in rt_mutex_postunlock(). */ mark_wakeup_next_waiter(wqh, lock); return true; /* call postunlock() */} void __sched rt_mutex_futex_unlock(struct rt_mutex_base *lock){ DEFINE_RT_WAKE_Q(wqh); unsigned long flags; bool postunlock; raw_spin_lock_irqsave(&lock->wait_lock, flags); postunlock = __rt_mutex_futex_unlock(lock, &wqh); raw_spin_unlock_irqrestore(&lock->wait_lock, flags); if (postunlock) rt_mutex_postunlock(&wqh);} /** * __rt_mutex_init - initialize the rt_mutex * * @lock: The rt_mutex to be initialized * @name: The lock name used for debugging * @key: The lock class key used for debugging * * Initialize the rt_mutex to unlocked state. * * Initializing of a locked rt_mutex is not allowed */void __sched __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key){ debug_check_no_locks_freed((void *)lock, sizeof(*lock)); __rt_mutex_base_init(&lock->rtmutex); lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP);}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 __sched rt_mutex_init_proxy_locked(struct rt_mutex_base *lock, struct task_struct *proxy_owner){ static struct lock_class_key pi_futex_key; __rt_mutex_base_init(lock); /* * On PREEMPT_RT the futex hashbucket spinlock becomes 'sleeping' * and rtmutex based. That causes a lockdep false positive, because * some of the futex functions invoke spin_unlock(&hb->lock) with * the wait_lock of the rtmutex associated to the pi_futex held. * spin_unlock() in turn takes wait_lock of the rtmutex on which * the spinlock is based, which makes lockdep notice a lock * recursion. Give the futex/rtmutex wait_lock a separate key. */ lockdep_set_class(&lock->wait_lock, &pi_futex_key); rt_mutex_set_owner(lock, proxy_owner);} /** * 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 just 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 __sched rt_mutex_proxy_unlock(struct rt_mutex_base *lock){ debug_rt_mutex_proxy_unlock(lock); rt_mutex_clear_owner(lock);} /** * __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 * @wake_q: the wake_q to wake tasks after we release the wait_lock * * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that. * * NOTE: does _NOT_ remove the @waiter on failure; must either call * rt_mutex_wait_proxy_lock() or rt_mutex_cleanup_proxy_lock() after this. * * Returns: * 0 - task blocked on lock * 1 - acquired the lock for task, caller should wake it up * <0 - error * * Special API call for PI-futex support. */int __sched __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter, struct task_struct *task, struct wake_q_head *wake_q) __must_hold(&lock->wait_lock){ int ret; lockdep_assert_held(&lock->wait_lock); 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, NULL, RT_MUTEX_FULL_CHAINWALK, wake_q); 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; } return ret;} /** * 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 * * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that. * * NOTE: unlike __rt_mutex_start_proxy_lock this _DOES_ remove the @waiter * on failure. * * Returns: * 0 - task blocked on lock * 1 - acquired the lock for task, caller should wake it up * <0 - error * * Special API call for PI-futex support. */int __sched rt_mutex_start_proxy_lock(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter, struct task_struct *task){ int ret; DEFINE_WAKE_Q(wake_q); raw_spin_lock_irq(&lock->wait_lock); ret = __rt_mutex_start_proxy_lock(lock, waiter, task, &wake_q); if (unlikely(ret < 0)) remove_waiter(lock, waiter); preempt_disable(); raw_spin_unlock_irq(&lock->wait_lock); wake_up_q(&wake_q); preempt_enable(); return ret;} /** * 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 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 __sched rt_mutex_wait_proxy_lock(struct rt_mutex_base *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_block(lock, NULL, TASK_INTERRUPTIBLE, to, waiter, NULL); /* * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might * have to fix that up. */ fixup_rt_mutex_waiters(lock, true); raw_spin_unlock_irq(&lock->wait_lock); return ret;} /** * 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_start_proxy_lock() or * 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 __sched rt_mutex_cleanup_proxy_lock(struct rt_mutex_base *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, false); raw_spin_unlock_irq(&lock->wait_lock); return cleanup;} /* * Recheck the pi chain, in case we got a priority setting * * Called from sched_setschedulerLines 1–500 of 683. Load more
// SPDX-License-Identifier: GPL-2.0-only /* * rtmutex API */ #include <linux/spinlock.h> #include <linux/export.h> #define RT_MUTEX_BUILD_MUTEX #include "rtmutex.c" /* * Max number of times we'll walk the boosting chain: */ int max_lock_depth = 1024; static const struct ctl_table rtmutex_sysctl_table[] = { { .procname = "max_lock_depth", .data = &max_lock_depth, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec, }, }; static int __init init_rtmutex_sysctl(void) { register_sysctl_init("kernel", rtmutex_sysctl_table); return 0; } subsys_initcall(init_rtmutex_sysctl); /* * 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 __always_inline int __rt_mutex_lock_common(struct rt_mutex *lock, unsigned int state, struct lockdep_map *nest_lock, unsigned int subclass) __cond_acquires(0, lock) { int ret; might_sleep(); mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, _RET_IP_); ret = __rt_mutex_lock(&lock->rtmutex, state); if (ret) mutex_release(&lock->dep_map, _RET_IP_); return ret; } void rt_mutex_base_init(struct rt_mutex_base *rtb) { __rt_mutex_base_init(rtb); } EXPORT_SYMBOL(rt_mutex_base_init); #ifdef CONFIG_DEBUG_LOCK_ALLOC /** * rt_mutex_lock_nested - lock a rt_mutex * * @lock: the rt_mutex to be locked * @subclass: the lockdep subclass */ void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass) { if (__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, subclass) == 0) return; /* * The code below is never reached because __rt_mutex_lock_common() only * returns an error code if interrupted by a signal or upon a timeout. */ WARN_ON_ONCE(true); __acquire(lock); } EXPORT_SYMBOL_GPL(rt_mutex_lock_nested); void __sched _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock) { if (__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, nest_lock, 0) == 0) return; /* * The code below is never reached because __rt_mutex_lock_common() only * returns an error code if interrupted by a signal or upon a timeout. */ WARN_ON_ONCE(true); __acquire(lock); } EXPORT_SYMBOL_GPL(_rt_mutex_lock_nest_lock); #else /* !CONFIG_DEBUG_LOCK_ALLOC */ /** * rt_mutex_lock - lock a rt_mutex * * @lock: the rt_mutex to be locked */ void __sched rt_mutex_lock(struct rt_mutex *lock) { if (__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, 0) == 0) return; /* * The code below is never reached because __rt_mutex_lock_common() only * returns an error code if interrupted by a signal or upon a timeout. */ WARN_ON_ONCE(true); __acquire(lock); } EXPORT_SYMBOL_GPL(rt_mutex_lock); #endif /** * 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) { return __rt_mutex_lock_common(lock, TASK_INTERRUPTIBLE, NULL, 0); } EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible); /** * rt_mutex_lock_killable - lock a rt_mutex killable * * @lock: the rt_mutex to be locked * * Returns: * 0 on success * -EINTR when interrupted by a signal */ int __sched rt_mutex_lock_killable(struct rt_mutex *lock) { return __rt_mutex_lock_common(lock, TASK_KILLABLE, NULL, 0); } EXPORT_SYMBOL_GPL(rt_mutex_lock_killable); /** * 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 or soft interrupt context. * * Returns: * 1 on success * 0 on contention */ int __sched rt_mutex_trylock(struct rt_mutex *lock) { int ret; if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task())) return 0; ret = __rt_mutex_trylock(&lock->rtmutex); if (ret) mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_); return ret; } 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, _RET_IP_); __rt_mutex_unlock(&lock->rtmutex); __release(lock); } EXPORT_SYMBOL_GPL(rt_mutex_unlock); /* * Futex variants, must not use fastpath. */ int __sched rt_mutex_futex_trylock(struct rt_mutex_base *lock) { return rt_mutex_slowtrylock(lock); } int __sched __rt_mutex_futex_trylock(struct rt_mutex_base *lock) { return __rt_mutex_slowtrylock(lock); } /** * __rt_mutex_futex_unlock - Futex variant, that since futex variants * do not use the fast-path, can be simple and will not need to retry. * * @lock: The rt_mutex to be unlocked * @wqh: The wake queue head from which to get the next lock waiter */ bool __sched __rt_mutex_futex_unlock(struct rt_mutex_base *lock, struct rt_wake_q_head *wqh) __must_hold(&lock->wait_lock) { lockdep_assert_held(&lock->wait_lock); debug_rt_mutex_unlock(lock); if (!rt_mutex_has_waiters(lock)) { lock->owner = NULL; return false; /* done */ } /* * mark_wakeup_next_waiter() deboosts and retains preemption * disabled when dropping the wait_lock, to avoid inversion prior * to the wakeup. preempt_disable() therein pairs with the * preempt_enable() in rt_mutex_postunlock(). */ mark_wakeup_next_waiter(wqh, lock); return true; /* call postunlock() */ } void __sched rt_mutex_futex_unlock(struct rt_mutex_base *lock) { DEFINE_RT_WAKE_Q(wqh); unsigned long flags; bool postunlock; raw_spin_lock_irqsave(&lock->wait_lock, flags); postunlock = __rt_mutex_futex_unlock(lock, &wqh); raw_spin_unlock_irqrestore(&lock->wait_lock, flags); if (postunlock) rt_mutex_postunlock(&wqh); } /** * __rt_mutex_init - initialize the rt_mutex * * @lock: The rt_mutex to be initialized * @name: The lock name used for debugging * @key: The lock class key used for debugging * * Initialize the rt_mutex to unlocked state. * * Initializing of a locked rt_mutex is not allowed */ void __sched __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key) { debug_check_no_locks_freed((void *)lock, sizeof(*lock)); __rt_mutex_base_init(&lock->rtmutex); lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP); } 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 __sched rt_mutex_init_proxy_locked(struct rt_mutex_base *lock, struct task_struct *proxy_owner) { static struct lock_class_key pi_futex_key; __rt_mutex_base_init(lock); /* * On PREEMPT_RT the futex hashbucket spinlock becomes 'sleeping' * and rtmutex based. That causes a lockdep false positive, because * some of the futex functions invoke spin_unlock(&hb->lock) with * the wait_lock of the rtmutex associated to the pi_futex held. * spin_unlock() in turn takes wait_lock of the rtmutex on which * the spinlock is based, which makes lockdep notice a lock * recursion. Give the futex/rtmutex wait_lock a separate key. */ lockdep_set_class(&lock->wait_lock, &pi_futex_key); rt_mutex_set_owner(lock, proxy_owner); } /** * 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 just 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 __sched rt_mutex_proxy_unlock(struct rt_mutex_base *lock) { debug_rt_mutex_proxy_unlock(lock); rt_mutex_clear_owner(lock); } /** * __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 * @wake_q: the wake_q to wake tasks after we release the wait_lock * * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that. * * NOTE: does _NOT_ remove the @waiter on failure; must either call * rt_mutex_wait_proxy_lock() or rt_mutex_cleanup_proxy_lock() after this. * * Returns: * 0 - task blocked on lock * 1 - acquired the lock for task, caller should wake it up * <0 - error * * Special API call for PI-futex support. */ int __sched __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter, struct task_struct *task, struct wake_q_head *wake_q) __must_hold(&lock->wait_lock) { int ret; lockdep_assert_held(&lock->wait_lock); 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, NULL, RT_MUTEX_FULL_CHAINWALK, wake_q); 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; } return ret; } /** * 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 * * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that. * * NOTE: unlike __rt_mutex_start_proxy_lock this _DOES_ remove the @waiter * on failure. * * Returns: * 0 - task blocked on lock * 1 - acquired the lock for task, caller should wake it up * <0 - error * * Special API call for PI-futex support. */ int __sched rt_mutex_start_proxy_lock(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter, struct task_struct *task) { int ret; DEFINE_WAKE_Q(wake_q); raw_spin_lock_irq(&lock->wait_lock); ret = __rt_mutex_start_proxy_lock(lock, waiter, task, &wake_q); if (unlikely(ret < 0)) remove_waiter(lock, waiter); preempt_disable(); raw_spin_unlock_irq(&lock->wait_lock); wake_up_q(&wake_q); preempt_enable(); return ret; } /** * 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 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 __sched rt_mutex_wait_proxy_lock(struct rt_mutex_base *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_block(lock, NULL, TASK_INTERRUPTIBLE, to, waiter, NULL); /* * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might * have to fix that up. */ fixup_rt_mutex_waiters(lock, true); raw_spin_unlock_irq(&lock->wait_lock); return ret; } /** * 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_start_proxy_lock() or * 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 __sched rt_mutex_cleanup_proxy_lock(struct rt_mutex_base *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, false); raw_spin_unlock_irq(&lock->wait_lock); return cleanup; } /* * Recheck the pi chain, in case we got a priority setting * * Called from sched_setscheduler