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Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull a mutex fix from Ingo Molnar.

Fix the fastpath_lock failure contention flag for xchg-based mutexes.

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  mutex: Place lock in contended state after fastpath_lock failure
This commit is contained in:
Linus Torvalds 2012-08-20 10:30:57 -07:00
commit fb34438914
1 changed files with 9 additions and 2 deletions
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11
include/asm-generic/mutex-xchg.h
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@ -26,7 +26,13 @@ static inline void
__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
{
if (unlikely(atomic_xchg(count, 0) != 1))
fail_fn(count);
/*
* We failed to acquire the lock, so mark it contended
* to ensure that any waiting tasks are woken up by the
* unlock slow path.
*/
if (likely(atomic_xchg(count, -1) != 1))
fail_fn(count);
}
/**
@ -43,7 +49,8 @@ static inline int
__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
{
if (unlikely(atomic_xchg(count, 0) != 1))
return fail_fn(count);
if (likely(atomic_xchg(count, -1) != 1))
return fail_fn(count);
return 0;
}