diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-10 16:19:40 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-10 16:19:40 -0700 |
| commit | e7241d771419b8a8671ebc46a043c324ccb0dcf7 (patch) | |
| tree | 77f1bc9c635e2ac29396816ce9ef9cbdb6853884 | |
| parent | 3f6280ddf25fa656d0e17960588e52bee48a7547 (diff) | |
| parent | 04dce7d9d429ea5ea04e9432d1726c930f4d67da (diff) | |
Merge branch 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
spinlock: Add missing __raw_spin_lock_flags() stub for UP
mutex: add atomic_dec_and_mutex_lock(), fix
locking, rtmutex.c: Documentation cleanup
mutex: add atomic_dec_and_mutex_lock()
| -rw-r--r-- | include/linux/mutex.h | 1 | ||||
| -rw-r--r-- | include/linux/spinlock_up.h | 1 | ||||
| -rw-r--r-- | kernel/mutex.c | 25 | ||||
| -rw-r--r-- | kernel/rtmutex.c | 8 |
4 files changed, 30 insertions, 5 deletions
diff --git a/include/linux/mutex.h b/include/linux/mutex.h index 3069ec7e0ab..878cab4f5fc 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -150,5 +150,6 @@ extern int __must_check mutex_lock_killable(struct mutex *lock); */ extern int mutex_trylock(struct mutex *lock); extern void mutex_unlock(struct mutex *lock); +extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); #endif diff --git a/include/linux/spinlock_up.h b/include/linux/spinlock_up.h index 938234c4a99..d4841ed8215 100644 --- a/include/linux/spinlock_up.h +++ b/include/linux/spinlock_up.h @@ -60,6 +60,7 @@ static inline void __raw_spin_unlock(raw_spinlock_t *lock) #define __raw_spin_is_locked(lock) ((void)(lock), 0) /* for sched.c and kernel_lock.c: */ # define __raw_spin_lock(lock) do { (void)(lock); } while (0) +# define __raw_spin_lock_flags(lock, flags) do { (void)(lock); } while (0) # define __raw_spin_unlock(lock) do { (void)(lock); } while (0) # define __raw_spin_trylock(lock) ({ (void)(lock); 1; }) #endif /* DEBUG_SPINLOCK */ diff --git a/kernel/mutex.c b/kernel/mutex.c index 6ca5fe96e39..e5cc0cd28d5 100644 --- a/kernel/mutex.c +++ b/kernel/mutex.c @@ -473,5 +473,28 @@ int __sched mutex_trylock(struct mutex *lock) return ret; } - EXPORT_SYMBOL(mutex_trylock); + +/** + * 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); diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c index fec77e7e056..820c5af44f3 100644 --- a/kernel/rtmutex.c +++ b/kernel/rtmutex.c @@ -891,9 +891,9 @@ int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock, 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 + * rt_mutex_timed_lock - 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) @@ -940,7 +940,7 @@ void __sched rt_mutex_unlock(struct rt_mutex *lock) } EXPORT_SYMBOL_GPL(rt_mutex_unlock); -/*** +/** * rt_mutex_destroy - mark a mutex unusable * @lock: the mutex to be destroyed * |