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authorLinus Torvalds <torvalds@linux-foundation.org>2012-08-20 10:30:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-08-20 10:30:57 -0700
commitfb34438914188cc271d07a5fc2903489b6e9ab2d (patch)
tree0cba437bc0e71e4014f0d47bc7c2a5780fe89294
parent0e665d5d1125f9f4ccff56a75e814f10f88861a2 (diff)
parent0bce9c46bf3b15f485d82d7e81dabed6ebcc24b1 (diff)
Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
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
-rw-r--r--include/asm-generic/mutex-xchg.h11
1 files changed, 9 insertions, 2 deletions
diff --git a/include/asm-generic/mutex-xchg.h b/include/asm-generic/mutex-xchg.h
index 580a6d35c70..c04e0db8a2d 100644
--- a/include/asm-generic/mutex-xchg.h
+++ b/include/asm-generic/mutex-xchg.h
@@ -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;
}