[PATCH] use smp_mb/wmb/rmb where possible

Replace a number of memory barriers with smp_ variants.  This means we won't
take the unnecessary hit on UP machines.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index cb0cd3c..33f7152 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -767,7 +767,7 @@
 	list_del(&receiver->list);
 	receiver->state = STATE_PENDING;
 	wake_up_process(receiver->task);
-	wmb();
+	smp_wmb();
 	receiver->state = STATE_READY;
 }
 
@@ -786,7 +786,7 @@
 	list_del(&sender->list);
 	sender->state = STATE_PENDING;
 	wake_up_process(sender->task);
-	wmb();
+	smp_wmb();
 	sender->state = STATE_READY;
 }