staging: android: describe use of memory barrier on sync.c

Added comments describing the purpose of using write memory
barrier in the context of sync_timeline_destory.

Signed-off-by: Niv Yehezkel <executerx@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c
index 1f88c5d..18174f7 100644 (file)
--- a/drivers/staging/android/sync.c
+++ b/drivers/staging/android/sync.c
@@ -92,6 +92,10 @@ static void sync_timeline_free(struct kref *kref)
 void sync_timeline_destroy(struct sync_timeline *obj)
 {
        obj->destroyed = true;
+       /*
+        * Ensure timeline is marked as destroyed before
+        * changing timeline's fences status.
+        */
        smp_wmb();
 
        /*