[IA64] Fix bug in ia64 specific down() function

Chen, Kenneth W wrote:
> The memory order semantics for include/asm-ia64/semaphore.h:down()
> doesn't look right.  It is using atomic_dec_return, which eventually
> translate into ia64_fetch_and_add() that uses release semantics.
> Shouldn't it use acquire semantics?

Use ia64_fetchadd() instead of atomic_dec_return()

Acked-by: Ken Chen <kenneth.w.chen@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/include/asm-ia64/semaphore.h b/include/asm-ia64/semaphore.h
index bb8906285fa..f483eeb95dd 100644
--- a/include/asm-ia64/semaphore.h
+++ b/include/asm-ia64/semaphore.h
@@ -61,7 +61,7 @@ static inline void
 down (struct semaphore *sem)
 {
         might_sleep();
-        if (atomic_dec_return(&sem->count) < 0)
+        if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)
                 __down(sem);
 }
 
@@ -75,7 +75,7 @@ down_interruptible (struct semaphore * sem)
         int ret = 0;
 
         might_sleep();
-        if (atomic_dec_return(&sem->count) < 0)
+        if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)
                 ret = __down_interruptible(sem);
         return ret;
 }
@@ -85,7 +85,7 @@ down_trylock (struct semaphore *sem)
 {
         int ret = 0;
 
-        if (atomic_dec_return(&sem->count) < 0)
+        if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)
                 ret = __down_trylock(sem);
         return ret;
 }
@@ -93,7 +93,7 @@ down_trylock (struct semaphore *sem)
 static inline void
 up (struct semaphore * sem)
 {
-        if (atomic_inc_return(&sem->count) <= 0)
+        if (ia64_fetchadd(1, &sem->count.counter, rel) <= -1)
                 __up(sem);
 }