From 23f78d4a03c53cbd75d87a795378ea540aa08c86 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Tue, 27 Jun 2006 02:54:53 -0700 Subject: [PATCH] pi-futex: rt mutex core Core functions for the rt-mutex subsystem. Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Signed-off-by: Arjan van de Ven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/rtmutex.c | 904 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 904 insertions(+) create mode 100644 kernel/rtmutex.c (limited to 'kernel/rtmutex.c') diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c new file mode 100644 index 000000000000..937a474fae94 --- /dev/null +++ b/kernel/rtmutex.c @@ -0,0 +1,904 @@ +/* + * 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 + * Copyright (C) 2005-2006 Timesys Corp., Thomas Gleixner + * Copyright (C) 2005 Kihon Technologies Inc., Steven Rostedt + * Copyright (C) 2006 Esben Nielsen + */ +#include +#include +#include +#include + +#include "rtmutex_common.h" + +#ifdef CONFIG_DEBUG_RT_MUTEXES +# include "rtmutex-debug.h" +#else +# include "rtmutex.h" +#endif + +/* + * lock->owner state tracking: + * + * lock->owner holds the task_struct pointer of the owner. Bit 0 and 1 + * are used to keep track of the "owner is pending" and "lock has + * waiters" state. + * + * owner bit1 bit0 + * NULL 0 0 lock is free (fast acquire possible) + * NULL 0 1 invalid state + * NULL 1 0 Transitional State* + * NULL 1 1 invalid state + * taskpointer 0 0 lock is held (fast release possible) + * taskpointer 0 1 task is pending owner + * taskpointer 1 0 lock is held and has waiters + * taskpointer 1 1 task is pending owner and lock has more waiters + * + * Pending ownership is assigned to the top (highest priority) + * waiter of the lock, when the lock is released. The thread is woken + * up and can now take the lock. Until the lock is taken (bit 0 + * cleared) a competing higher priority thread can steal the lock + * which puts the woken up thread back on the waiters list. + * + * The fast atomic compare exchange based acquire and release is only + * possible when bit 0 and 1 of lock->owner are 0. + * + * (*) There's a small time where the owner can be NULL and the + * "lock has waiters" bit is set. This can happen when grabbing the lock. + * To prevent a cmpxchg of the owner releasing the lock, we need to set this + * bit before looking at the lock, hence the reason this is a transitional + * state. + */ + +static void +rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner, + unsigned long mask) +{ + unsigned long val = (unsigned long)owner | mask; + + if (rt_mutex_has_waiters(lock)) + val |= RT_MUTEX_HAS_WAITERS; + + lock->owner = (struct task_struct *)val; +} + +static inline void clear_rt_mutex_waiters(struct rt_mutex *lock) +{ + lock->owner = (struct task_struct *) + ((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS); +} + +static void fixup_rt_mutex_waiters(struct rt_mutex *lock) +{ + if (!rt_mutex_has_waiters(lock)) + clear_rt_mutex_waiters(lock); +} + +/* + * We can speed up the acquire/release, if the architecture + * supports cmpxchg and if there's no debugging state to be set up + */ +#if defined(__HAVE_ARCH_CMPXCHG) && !defined(CONFIG_DEBUG_RT_MUTEXES) +# define rt_mutex_cmpxchg(l,c,n) (cmpxchg(&l->owner, c, n) == c) +static inline void mark_rt_mutex_waiters(struct rt_mutex *lock) +{ + unsigned long owner, *p = (unsigned long *) &lock->owner; + + do { + owner = *p; + } while (cmpxchg(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner); +} +#else +# define rt_mutex_cmpxchg(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); +} +#endif + +/* + * Calculate task priority from the waiter list priority + * + * Return task->normal_prio when the waiter list is empty or when + * the waiter is not allowed to do priority boosting + */ +int rt_mutex_getprio(struct task_struct *task) +{ + if (likely(!task_has_pi_waiters(task))) + return task->normal_prio; + + return min(task_top_pi_waiter(task)->pi_list_entry.prio, + task->normal_prio); +} + +/* + * Adjust the priority of a task, after its pi_waiters got modified. + * + * This can be both boosting and unboosting. task->pi_lock must be held. + */ +static void __rt_mutex_adjust_prio(struct task_struct *task) +{ + int prio = rt_mutex_getprio(task); + + if (task->prio != prio) + rt_mutex_setprio(task, prio); +} + +/* + * Adjust task priority (undo boosting). Called from the exit path of + * rt_mutex_slowunlock() and rt_mutex_slowlock(). + * + * (Note: We do this outside of the protection of lock->wait_lock to + * allow the lock to be taken while or before we readjust the priority + * of task. We do not use the spin_xx_mutex() variants here as we are + * outside of the debug path.) + */ +static void rt_mutex_adjust_prio(struct task_struct *task) +{ + unsigned long flags; + + spin_lock_irqsave(&task->pi_lock, flags); + __rt_mutex_adjust_prio(task); + spin_unlock_irqrestore(&task->pi_lock, flags); +} + +/* + * Max number of times we'll walk the boosting chain: + */ +int max_lock_depth = 1024; + +/* + * Adjust the priority chain. Also used for deadlock detection. + * Decreases task's usage by one - may thus free the task. + * Returns 0 or -EDEADLK. + */ +static int rt_mutex_adjust_prio_chain(task_t *task, + int deadlock_detect, + struct rt_mutex *orig_lock, + struct rt_mutex_waiter *orig_waiter + __IP_DECL__) +{ + struct rt_mutex *lock; + struct rt_mutex_waiter *waiter, *top_waiter = orig_waiter; + int detect_deadlock, ret = 0, depth = 0; + unsigned long flags; + + detect_deadlock = debug_rt_mutex_detect_deadlock(orig_waiter, + deadlock_detect); + + /* + * 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: + 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, + current->comm, current->pid); + } + put_task_struct(task); + + return deadlock_detect ? -EDEADLK : 0; + } + retry: + /* + * Task can not go away as we did a get_task() before ! + */ + spin_lock_irqsave(&task->pi_lock, flags); + + waiter = task->pi_blocked_on; + /* + * 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 || !waiter->task) + goto out_unlock_pi; + + if (top_waiter && (!task_has_pi_waiters(task) || + top_waiter != task_top_pi_waiter(task))) + goto out_unlock_pi; + + /* + * When deadlock detection is off then we check, if further + * priority adjustment is necessary. + */ + if (!detect_deadlock && waiter->list_entry.prio == task->prio) + goto out_unlock_pi; + + lock = waiter->lock; + if (!spin_trylock(&lock->wait_lock)) { + spin_unlock_irqrestore(&task->pi_lock, flags); + cpu_relax(); + goto retry; + } + + /* Deadlock detection */ + if (lock == orig_lock || rt_mutex_owner(lock) == current) { + debug_rt_mutex_deadlock(deadlock_detect, orig_waiter, lock); + spin_unlock(&lock->wait_lock); + ret = deadlock_detect ? -EDEADLK : 0; + goto out_unlock_pi; + } + + top_waiter = rt_mutex_top_waiter(lock); + + /* Requeue the waiter */ + plist_del(&waiter->list_entry, &lock->wait_list); + waiter->list_entry.prio = task->prio; + plist_add(&waiter->list_entry, &lock->wait_list); + + /* Release the task */ + spin_unlock_irqrestore(&task->pi_lock, flags); + put_task_struct(task); + + /* Grab the next task */ + task = rt_mutex_owner(lock); + spin_lock_irqsave(&task->pi_lock, flags); + + if (waiter == rt_mutex_top_waiter(lock)) { + /* Boost the owner */ + plist_del(&top_waiter->pi_list_entry, &task->pi_waiters); + waiter->pi_list_entry.prio = waiter->list_entry.prio; + plist_add(&waiter->pi_list_entry, &task->pi_waiters); + __rt_mutex_adjust_prio(task); + + } else if (top_waiter == waiter) { + /* Deboost the owner */ + plist_del(&waiter->pi_list_entry, &task->pi_waiters); + waiter = rt_mutex_top_waiter(lock); + waiter->pi_list_entry.prio = waiter->list_entry.prio; + plist_add(&waiter->pi_list_entry, &task->pi_waiters); + __rt_mutex_adjust_prio(task); + } + + get_task_struct(task); + spin_unlock_irqrestore(&task->pi_lock, flags); + + top_waiter = rt_mutex_top_waiter(lock); + spin_unlock(&lock->wait_lock); + + if (!detect_deadlock && waiter != top_waiter) + goto out_put_task; + + goto again; + + out_unlock_pi: + spin_unlock_irqrestore(&task->pi_lock, flags); + out_put_task: + put_task_struct(task); + return ret; +} + +/* + * Optimization: check if we can steal the lock from the + * assigned pending owner [which might not have taken the + * lock yet]: + */ +static inline int try_to_steal_lock(struct rt_mutex *lock) +{ + struct task_struct *pendowner = rt_mutex_owner(lock); + struct rt_mutex_waiter *next; + unsigned long flags; + + if (!rt_mutex_owner_pending(lock)) + return 0; + + if (pendowner == current) + return 1; + + spin_lock_irqsave(&pendowner->pi_lock, flags); + if (current->prio >= pendowner->prio) { + spin_unlock_irqrestore(&pendowner->pi_lock, flags); + return 0; + } + + /* + * Check if a waiter is enqueued on the pending owners + * pi_waiters list. Remove it and readjust pending owners + * priority. + */ + if (likely(!rt_mutex_has_waiters(lock))) { + spin_unlock_irqrestore(&pendowner->pi_lock, flags); + return 1; + } + + /* No chain handling, pending owner is not blocked on anything: */ + next = rt_mutex_top_waiter(lock); + plist_del(&next->pi_list_entry, &pendowner->pi_waiters); + __rt_mutex_adjust_prio(pendowner); + spin_unlock_irqrestore(&pendowner->pi_lock, flags); + + /* + * We are going to steal the lock and a waiter was + * enqueued on the pending owners pi_waiters queue. So + * we have to enqueue this waiter into + * current->pi_waiters list. This covers the case, + * where current is boosted because it holds another + * lock and gets unboosted because the booster is + * interrupted, so we would delay a waiter with higher + * priority as current->normal_prio. + * + * Note: in the rare case of a SCHED_OTHER task changing + * its priority and thus stealing the lock, next->task + * might be current: + */ + if (likely(next->task != current)) { + spin_lock_irqsave(¤t->pi_lock, flags); + plist_add(&next->pi_list_entry, ¤t->pi_waiters); + __rt_mutex_adjust_prio(current); + spin_unlock_irqrestore(¤t->pi_lock, flags); + } + return 1; +} + +/* + * Try to take an rt-mutex + * + * This fails + * - when the lock has a real owner + * - when a different pending owner exists and has higher priority than current + * + * Must be called with lock->wait_lock held. + */ +static int try_to_take_rt_mutex(struct rt_mutex *lock __IP_DECL__) +{ + /* + * We have to be careful here if the atomic speedups are + * enabled, such that, when + * - no other waiter is on the lock + * - the lock has been released since we did the cmpxchg + * the lock can be released or taken while we are doing the + * checks and marking the lock with RT_MUTEX_HAS_WAITERS. + * + * The atomic acquire/release aware variant of + * mark_rt_mutex_waiters uses a cmpxchg loop. After setting + * the WAITERS bit, the atomic release / acquire can not + * happen anymore and lock->wait_lock protects us from the + * non-atomic case. + * + * Note, that this might set lock->owner = + * RT_MUTEX_HAS_WAITERS in the case the lock is not contended + * any more. This is fixed up when we take the ownership. + * This is the transitional state explained at the top of this file. + */ + mark_rt_mutex_waiters(lock); + + if (rt_mutex_owner(lock) && !try_to_steal_lock(lock)) + return 0; + + /* We got the lock. */ + debug_rt_mutex_lock(lock __IP__); + + rt_mutex_set_owner(lock, current, 0); + + rt_mutex_deadlock_account_lock(lock, current); + + return 1; +} + +/* + * Task blocks on lock. + * + * Prepare waiter and propagate pi chain + * + * This must be called with lock->wait_lock held. + */ +static int task_blocks_on_rt_mutex(struct rt_mutex *lock, + struct rt_mutex_waiter *waiter, + int detect_deadlock + __IP_DECL__) +{ + struct rt_mutex_waiter *top_waiter = waiter; + task_t *owner = rt_mutex_owner(lock); + int boost = 0, res; + unsigned long flags; + + spin_lock_irqsave(¤t->pi_lock, flags); + __rt_mutex_adjust_prio(current); + waiter->task = current; + waiter->lock = lock; + plist_node_init(&waiter->list_entry, current->prio); + plist_node_init(&waiter->pi_list_entry, current->prio); + + /* Get the top priority waiter on the lock */ + if (rt_mutex_has_waiters(lock)) + top_waiter = rt_mutex_top_waiter(lock); + plist_add(&waiter->list_entry, &lock->wait_list); + + current->pi_blocked_on = waiter; + + spin_unlock_irqrestore(¤t->pi_lock, flags); + + if (waiter == rt_mutex_top_waiter(lock)) { + spin_lock_irqsave(&owner->pi_lock, flags); + plist_del(&top_waiter->pi_list_entry, &owner->pi_waiters); + plist_add(&waiter->pi_list_entry, &owner->pi_waiters); + + __rt_mutex_adjust_prio(owner); + if (owner->pi_blocked_on) { + boost = 1; + get_task_struct(owner); + } + spin_unlock_irqrestore(&owner->pi_lock, flags); + } + else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock)) { + spin_lock_irqsave(&owner->pi_lock, flags); + if (owner->pi_blocked_on) { + boost = 1; + get_task_struct(owner); + } + spin_unlock_irqrestore(&owner->pi_lock, flags); + } + if (!boost) + return 0; + + spin_unlock(&lock->wait_lock); + + res = rt_mutex_adjust_prio_chain(owner, detect_deadlock, lock, + waiter __IP__); + + spin_lock(&lock->wait_lock); + + return res; +} + +/* + * Wake up the next waiter on the lock. + * + * Remove the top waiter from the current tasks waiter list and from + * the lock waiter list. Set it as pending owner. Then wake it up. + * + * Called with lock->wait_lock held. + */ +static void wakeup_next_waiter(struct rt_mutex *lock) +{ + struct rt_mutex_waiter *waiter; + struct task_struct *pendowner; + unsigned long flags; + + spin_lock_irqsave(¤t->pi_lock, flags); + + waiter = rt_mutex_top_waiter(lock); + plist_del(&waiter->list_entry, &lock->wait_list); + + /* + * Remove it from current->pi_waiters. We do not adjust a + * possible priority boost right now. We execute wakeup in the + * boosted mode and go back to normal after releasing + * lock->wait_lock. + */ + plist_del(&waiter->pi_list_entry, ¤t->pi_waiters); + pendowner = waiter->task; + waiter->task = NULL; + + rt_mutex_set_owner(lock, pendowner, RT_MUTEX_OWNER_PENDING); + + spin_unlock_irqrestore(¤t->pi_lock, flags); + + /* + * Clear the pi_blocked_on variable and enqueue a possible + * waiter into the pi_waiters list of the pending owner. This + * prevents that in case the pending owner gets unboosted a + * waiter with higher priority than pending-owner->normal_prio + * is blocked on the unboosted (pending) owner. + */ + spin_lock_irqsave(&pendowner->pi_lock, flags); + + WARN_ON(!pendowner->pi_blocked_on); + WARN_ON(pendowner->pi_blocked_on != waiter); + WARN_ON(pendowner->pi_blocked_on->lock != lock); + + pendowner->pi_blocked_on = NULL; + + if (rt_mutex_has_waiters(lock)) { + struct rt_mutex_waiter *next; + + next = rt_mutex_top_waiter(lock); + plist_add(&next->pi_list_entry, &pendowner->pi_waiters); + } + spin_unlock_irqrestore(&pendowner->pi_lock, flags); + + wake_up_process(pendowner); +} + +/* + * Remove a waiter from a lock + * + * Must be called with lock->wait_lock held + */ +static void remove_waiter(struct rt_mutex *lock, + struct rt_mutex_waiter *waiter __IP_DECL__) +{ + int first = (waiter == rt_mutex_top_waiter(lock)); + int boost = 0; + task_t *owner = rt_mutex_owner(lock); + unsigned long flags; + + spin_lock_irqsave(¤t->pi_lock, flags); + plist_del(&waiter->list_entry, &lock->wait_list); + waiter->task = NULL; + current->pi_blocked_on = NULL; + spin_unlock_irqrestore(¤t->pi_lock, flags); + + if (first && owner != current) { + + spin_lock_irqsave(&owner->pi_lock, flags); + + plist_del(&waiter->pi_list_entry, &owner->pi_waiters); + + if (rt_mutex_has_waiters(lock)) { + struct rt_mutex_waiter *next; + + next = rt_mutex_top_waiter(lock); + plist_add(&next->pi_list_entry, &owner->pi_waiters); + } + __rt_mutex_adjust_prio(owner); + + if (owner->pi_blocked_on) { + boost = 1; + get_task_struct(owner); + } + spin_unlock_irqrestore(&owner->pi_lock, flags); + } + + WARN_ON(!plist_node_empty(&waiter->pi_list_entry)); + + if (!boost) + return; + + spin_unlock(&lock->wait_lock); + + rt_mutex_adjust_prio_chain(owner, 0, lock, NULL __IP__); + + spin_lock(&lock->wait_lock); +} + +/* + * Slow path lock function: + */ +static int __sched +rt_mutex_slowlock(struct rt_mutex *lock, int state, + struct hrtimer_sleeper *timeout, + int detect_deadlock __IP_DECL__) +{ + struct rt_mutex_waiter waiter; + int ret = 0; + + debug_rt_mutex_init_waiter(&waiter); + waiter.task = NULL; + + spin_lock(&lock->wait_lock); + + /* Try to acquire the lock again: */ + if (try_to_take_rt_mutex(lock __IP__)) { + spin_unlock(&lock->wait_lock); + return 0; + } + + set_current_state(state); + + /* Setup the timer, when timeout != NULL */ + if (unlikely(timeout)) + hrtimer_start(&timeout->timer, timeout->timer.expires, + HRTIMER_ABS); + + for (;;) { + /* Try to acquire the lock: */ + if (try_to_take_rt_mutex(lock __IP__)) + break; + + /* + * TASK_INTERRUPTIBLE checks for signals and + * timeout. Ignored otherwise. + */ + if (unlikely(state == TASK_INTERRUPTIBLE)) { + /* Signal pending? */ + if (signal_pending(current)) + ret = -EINTR; + if (timeout && !timeout->task) + ret = -ETIMEDOUT; + if (ret) + break; + } + + /* + * waiter.task is NULL the first time we come here and + * when we have been woken up by the previous owner + * but the lock got stolen by a higher prio task. + */ + if (!waiter.task) { + ret = task_blocks_on_rt_mutex(lock, &waiter, + detect_deadlock __IP__); + /* + * If we got woken up by the owner then start loop + * all over without going into schedule to try + * to get the lock now: + */ + if (unlikely(!waiter.task)) + continue; + + if (unlikely(ret)) + break; + } + spin_unlock(&lock->wait_lock); + + debug_rt_mutex_print_deadlock(&waiter); + + schedule(); + + spin_lock(&lock->wait_lock); + set_current_state(state); + } + + set_current_state(TASK_RUNNING); + + if (unlikely(waiter.task)) + remove_waiter(lock, &waiter __IP__); + + /* + * try_to_take_rt_mutex() sets the waiter bit + * unconditionally. We might have to fix that up. + */ + fixup_rt_mutex_waiters(lock); + + spin_unlock(&lock->wait_lock); + + /* Remove pending timer: */ + if (unlikely(timeout)) + hrtimer_cancel(&timeout->timer); + + /* + * Readjust priority, when we did not get the lock. We might + * have been the pending owner and boosted. Since we did not + * take the lock, the PI boost has to go. + */ + if (unlikely(ret)) + rt_mutex_adjust_prio(current); + + debug_rt_mutex_free_waiter(&waiter); + + return ret; +} + +/* + * Slow path try-lock function: + */ +static inline int +rt_mutex_slowtrylock(struct rt_mutex *lock __IP_DECL__) +{ + int ret = 0; + + spin_lock(&lock->wait_lock); + + if (likely(rt_mutex_owner(lock) != current)) { + + ret = try_to_take_rt_mutex(lock __IP__); + /* + * try_to_take_rt_mutex() sets the lock waiters + * bit unconditionally. Clean this up. + */ + fixup_rt_mutex_waiters(lock); + } + + spin_unlock(&lock->wait_lock); + + return ret; +} + +/* + * Slow path to release a rt-mutex: + */ +static void __sched +rt_mutex_slowunlock(struct rt_mutex *lock) +{ + spin_lock(&lock->wait_lock); + + debug_rt_mutex_unlock(lock); + + rt_mutex_deadlock_account_unlock(current); + + if (!rt_mutex_has_waiters(lock)) { + lock->owner = NULL; + spin_unlock(&lock->wait_lock); + return; + } + + wakeup_next_waiter(lock); + + spin_unlock(&lock->wait_lock); + + /* Undo pi boosting if necessary: */ + rt_mutex_adjust_prio(current); +} + +/* + * 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 detect_deadlock, + int (*slowfn)(struct rt_mutex *lock, int state, + struct hrtimer_sleeper *timeout, + int detect_deadlock __IP_DECL__)) +{ + if (!detect_deadlock && likely(rt_mutex_cmpxchg(lock, NULL, current))) { + rt_mutex_deadlock_account_lock(lock, current); + return 0; + } else + return slowfn(lock, state, NULL, detect_deadlock __RET_IP__); +} + +static inline int +rt_mutex_timed_fastlock(struct rt_mutex *lock, int state, + struct hrtimer_sleeper *timeout, int detect_deadlock, + int (*slowfn)(struct rt_mutex *lock, int state, + struct hrtimer_sleeper *timeout, + int detect_deadlock __IP_DECL__)) +{ + if (!detect_deadlock && likely(rt_mutex_cmpxchg(lock, NULL, current))) { + rt_mutex_deadlock_account_lock(lock, current); + return 0; + } else + return slowfn(lock, state, timeout, detect_deadlock __RET_IP__); +} + +static inline int +rt_mutex_fasttrylock(struct rt_mutex *lock, + int (*slowfn)(struct rt_mutex *lock __IP_DECL__)) +{ + if (likely(rt_mutex_cmpxchg(lock, NULL, current))) { + rt_mutex_deadlock_account_lock(lock, current); + return 1; + } + return slowfn(lock __RET_IP__); +} + +static inline void +rt_mutex_fastunlock(struct rt_mutex *lock, + void (*slowfn)(struct rt_mutex *lock)) +{ + if (likely(rt_mutex_cmpxchg(lock, current, NULL))) + rt_mutex_deadlock_account_unlock(current); + else + slowfn(lock); +} + +/** + * 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(); + + rt_mutex_fastlock(lock, TASK_UNINTERRUPTIBLE, 0, rt_mutex_slowlock); +} +EXPORT_SYMBOL_GPL(rt_mutex_lock); + +/** + * rt_mutex_lock_interruptible - lock a rt_mutex interruptible + * + * @lock: the rt_mutex to be locked + * @detect_deadlock: deadlock detection on/off + * + * Returns: + * 0 on success + * -EINTR when interrupted by a signal + * -EDEADLK when the lock would deadlock (when deadlock detection is on) + */ +int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock, + int detect_deadlock) +{ + might_sleep(); + + return rt_mutex_fastlock(lock, TASK_INTERRUPTIBLE, + detect_deadlock, rt_mutex_slowlock); +} +EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible); + +/** + * rt_mutex_lock_interruptible_ktime - 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) + * @detect_deadlock: deadlock detection on/off + * + * Returns: + * 0 on success + * -EINTR when interrupted by a signal + * -ETIMEOUT when the timeout expired + * -EDEADLK when the lock would deadlock (when deadlock detection is on) + */ +int +rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout, + int detect_deadlock) +{ + might_sleep(); + + return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout, + detect_deadlock, rt_mutex_slowlock); +} +EXPORT_SYMBOL_GPL(rt_mutex_timed_lock); + +/** + * rt_mutex_trylock - try to lock a rt_mutex + * + * @lock: the rt_mutex to be locked + * + * Returns 1 on success and 0 on contention + */ +int __sched rt_mutex_trylock(struct rt_mutex *lock) +{ + return rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock); +} +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) +{ + rt_mutex_fastunlock(lock, rt_mutex_slowunlock); +} +EXPORT_SYMBOL_GPL(rt_mutex_unlock); + +/*** + * 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 +} + +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) +{ + lock->owner = NULL; + spin_lock_init(&lock->wait_lock); + plist_head_init(&lock->wait_list, &lock->wait_lock); + + debug_rt_mutex_init(lock, name); +} +EXPORT_SYMBOL_GPL(__rt_mutex_init); -- cgit v1.2.3-59-g8ed1b