[PATCH] add missing memory barriers to ipc/sem.c

[Manfred Spraul <manfred@colorfullife.com>]

Hi Linus,

Two smp_wmb() statements are missing in the sysv sem code: This could 
cause stack corruptions.
The attached patch adds them.

Signed-Off-By: Manfred Spraul <manfred@colorfullife.com>

--- 2.6/ipc/sem.c	2005-12-19 01:36:54.000000000 +0100
+++ build-2.6/ipc/sem.c	2005-12-23 23:25:17.000000000 +0100
@@ -381,6 +381,7 @@
 			/* hands-off: q will disappear immediately after
 			 * writing q->status.
 			 */
+			smb_wmb();
 			q->status = error;
 			q = n;
 		} else {
@@ -461,6 +462,7 @@
 		n = q->next;
 		q->status = IN_WAKEUP;
 		wake_up_process(q->sleeper); /* doesn't sleep */
+		smp_wmb();
 		q->status = -EIDRM;	/* hands-off q */
 		q = n;
 	}