Use volatile access and relax_cpu() in queue lock.

1 files changed, 4 insertions, 3 deletions

diff --git a/include/linux/queuelock.h b/include/linux/queuelock.h
index 3fad15deab..454ff817fb 100644
--- a/include/linux/queuelock.h
+++ b/include/linux/queuelock.h
@@ -58,6 +58,7 @@ static inline void queue_lock_init(queuelock_t *lock)
 static inline void queue_lock(queuelock_t *lock)
 {
         int me = smp_processor_id();
+        volatile int* spin_var;
         /* Get slot to spin on. atomic_inc_return() returns the incremented
          * value, so take one of again
          */
@@ -71,9 +72,9 @@ static inline void queue_lock(queuelock_t *lock)
         /* range limit*/
         lock->spin_slot[me] %= NR_CPUS;
         /* spin until you acquire the lock */
-        while (lock->slots[lock->spin_slot[me]].val == MUST_WAIT)
-//              rep_nop();
-                ;
+        spin_var = (int*) &lock->slots[lock->spin_slot[me]].val;
+        while (*spin_var == MUST_WAIT)
+                cpu_relax();            
 
         /* reset the lock */
         lock->slots[lock->spin_slot[me]].val = MUST_WAIT;