[PATCH 2/4] locking/rtmutex: Use cmp-cmpxchg

[Davidlohr Bueso]

Avoid unnecessary cmpxchg calls, all of our other locks
use it as well.

Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
---
 kernel/locking/rtmutex.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 74188d8..1d5cc9d 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -74,7 +74,9 @@ static void fixup_rt_mutex_waiters(struct rt_mutex *lock)
  * set up.
  */
 #ifndef CONFIG_DEBUG_RT_MUTEXES
-# define rt_mutex_cmpxchg(l,c,n)	(cmpxchg(&l->owner, c, n) == c)
+# define rt_mutex_cmpxchg(l,c,n) \
+	(l->owner == c && cmpxchg(&l->owner, c, n) == c)
+
 static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
 {
 	unsigned long owner, *p = (unsigned long *) &lock->owner;
-- 
2.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/