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authorSamuel Thibault <samuel.thibault@ens-lyon.org>2011-05-08 23:11:02 +0200
committerSamuel Thibault <samuel.thibault@ens-lyon.org>2011-05-08 23:11:02 +0200
commitcded208c7ea6d107dcbfdb2e2d4622daf41c2886 (patch)
treea04a03736b0a928c2954382f924aadb105ee39cc /libdde_linux26/contrib/kernel/.svn/text-base/mutex.c.svn-base
parentfc82e00ca1e174cb961dea6ad37622e9b26cd899 (diff)
remove .svn directories
Diffstat (limited to 'libdde_linux26/contrib/kernel/.svn/text-base/mutex.c.svn-base')
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-/*
- * 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.
- *
- * Also see Documentation/mutex-design.txt.
- */
-#include <linux/mutex.h>
-#include <linux/sched.h>
-#include <linux/module.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
-
-/***
- * mutex_init - initialize the mutex
- * @lock: the mutex to be initialized
- * @key: the lock_class_key for the class; used by mutex lock debugging
- *
- * Initialize the mutex to unlocked state.
- *
- * It is not allowed to initialize an already locked mutex.
- */
-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);
-
- 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 inline __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);
-}
-
-EXPORT_SYMBOL(mutex_lock);
-#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:
- */
- __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,
- unsigned long ip)
-{
- struct task_struct *task = current;
- struct mutex_waiter waiter;
- unsigned int old_val;
- unsigned long flags;
-
- spin_lock_mutex(&lock->wait_lock, flags);
-
- debug_mutex_lock_common(lock, &waiter);
- mutex_acquire(&lock->dep_map, subclass, 0, ip);
- 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;
-
- old_val = atomic_xchg(&lock->count, -1);
- if (old_val == 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:
- */
- old_val = atomic_xchg(&lock->count, -1);
- if (old_val == 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);
- return -EINTR;
- }
- __set_task_state(task, state);
-
- /* didnt get the lock, go to sleep: */
- spin_unlock_mutex(&lock->wait_lock, flags);
- schedule();
- spin_lock_mutex(&lock->wait_lock, flags);
- }
-
-done:
- lock_acquired(&lock->dep_map, ip);
- /* got the lock - rejoice! */
- mutex_remove_waiter(lock, &waiter, task_thread_info(task));
- debug_mutex_set_owner(lock, task_thread_info(task));
-
- /* 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);
-
- 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, _RET_IP_);
-}
-
-EXPORT_SYMBOL_GPL(mutex_lock_nested);
-
-int __sched
-mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass)
-{
- might_sleep();
- return __mutex_lock_common(lock, TASK_KILLABLE, subclass, _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, _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);
- }
-
- debug_mutex_clear_owner(lock);
-
- 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);
-
-/***
- * mutex_lock_interruptible - acquire the mutex, interruptable
- * @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)
-{
- might_sleep();
- return __mutex_fastpath_lock_retval
- (&lock->count, __mutex_lock_interruptible_slowpath);
-}
-
-EXPORT_SYMBOL(mutex_lock_interruptible);
-
-int __sched mutex_lock_killable(struct mutex *lock)
-{
- might_sleep();
- return __mutex_fastpath_lock_retval
- (&lock->count, __mutex_lock_killable_slowpath);
-}
-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, _RET_IP_);
-}
-
-static noinline int __sched
-__mutex_lock_killable_slowpath(atomic_t *lock_count)
-{
- struct mutex *lock = container_of(lock_count, struct mutex, count);
-
- return __mutex_lock_common(lock, TASK_KILLABLE, 0, _RET_IP_);
-}
-
-static noinline int __sched
-__mutex_lock_interruptible_slowpath(atomic_t *lock_count)
-{
- struct mutex *lock = container_of(lock_count, struct mutex, count);
-
- return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, _RET_IP_);
-}
-#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)) {
- debug_mutex_set_owner(lock, current_thread_info());
- 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 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 to 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)
-{
- return __mutex_fastpath_trylock(&lock->count,
- __mutex_trylock_slowpath);
-}
-
-EXPORT_SYMBOL(mutex_trylock);