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Subject[GIT PULL] core kernel fix
Linus,

Please pull the latest core-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-urgent-for-linus

HEAD: 0bce9c46bf3b15f485d82d7e81dabed6ebcc24b1 mutex: Place lock in contended state after fastpath_lock failure

Thanks,

Ingo

------------------>
Will Deacon (1):
mutex: Place lock in contended state after fastpath_lock failure


include/asm-generic/mutex-xchg.h | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/mutex-xchg.h b/include/asm-generic/mutex-xchg.h
index 580a6d3..c04e0db 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;
}


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