From 1def1dc91715acdb6dddfaed1a44149d42d8063c Mon Sep 17 00:00:00 2001
From: liguang <lig.fnst@cn.fujitsu.com>
Date: Tue, 30 Apr 2013 15:27:25 -0700
Subject: [PATCH] kernel/smp.c: use '|=' for csd_lock

csd_lock() uses assignment to data->flags rather than |=.  That is not
buggy at present because only one bit (CSD_FLAG_LOCK) is defined in
call_single_data.flags.

But it will become buggy if we later add another flag, so fix it now.

Signed-off-by: liguang <lig.fnst@cn.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 kernel/smp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index 8e451f3ff51b..b320622543e9 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -109,7 +109,7 @@ static void csd_lock_wait(struct call_single_data *data)
 static void csd_lock(struct call_single_data *data)
 {
 	csd_lock_wait(data);
-	data->flags = CSD_FLAG_LOCK;
+	data->flags |= CSD_FLAG_LOCK;
 
 	/*
 	 * prevent CPU from reordering the above assignment
-- 
2.20.1