From: Ralf Baechle <ralf@linux-mips.org>
Date: Thu, 7 Dec 2006 04:40:26 +0000 (-0800)
Subject: [PATCH] futex: remove unneeded barrier
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=ccdea2f88b5689f0fd29c3804be43a3acf0311e3;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

[PATCH] futex: remove unneeded barrier

When disassembling a kernel I found around over 90 sync Instructions from
mb, rmb and wmb calls in the kernel and only few of those make any sense to
me.  So here's the first one - I think the wmb() in kernel/futex.c is not
needed on uniprocessors so should become an smb_wmb().

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/kernel/futex.c b/kernel/futex.c
index d60b7f7a8cc3..a8302a1620ea 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -552,7 +552,7 @@ static void wake_futex(struct futex_q *q)
 	 * at the end of wake_up_all() does not prevent this store from
 	 * moving.
 	 */
-	wmb();
+	smp_wmb();
 	q->lock_ptr = NULL;
 }