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yaml
---
r: 145947
b: refs/heads/master
c: a511e3f
h: refs/heads/master
i:
  145945: 6cff429
  145943: f79c550
v: v3
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Andrew Morton authored and Ingo Molnar committed Apr 30, 2009
1 parent 7251832 commit fcff743
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Showing 3 changed files with 26 additions and 25 deletions.
2 changes: 1 addition & 1 deletion [refs]
Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: 23b94b967f118bef941369238f33c8140be46539
refs/heads/master: a511e3f968c462a55ef58697257f5347c73d306e
24 changes: 1 addition & 23 deletions trunk/include/linux/mutex.h
Original file line number Diff line number Diff line change
Expand Up @@ -150,28 +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);

/**
* 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
*/
static inline 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;
}
extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);

#endif
25 changes: 24 additions & 1 deletion trunk/kernel/mutex.c
Original file line number Diff line number Diff line change
Expand Up @@ -471,5 +471,28 @@ 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);

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