linux-kernel - [PATCH] doc: memory-barriers.txt: Add barrier() to provide ordering

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Date:	Mon, 11 Aug 2014 18:51:40 -0400
From:	Pranith Kumar <bobby.prani@...il.com>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Josh Triplett <josh@...htriplett.org>,
	David Howells <dhowells@...hat.com>,
	Masanari Iida <standby24x7@...il.com>,
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] doc: memory-barriers.txt: Add barrier() to provide ordering

In the provably false case, add barrier() in both the legs of the if() condition
to provide ordering.

Signed-off-by: Pranith Kumar <bobby.prani@...il.com>
---
 Documentation/memory-barriers.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index 41a6c9c..0f2903f 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -689,9 +689,11 @@ should do something like the following:
 	q = ACCESS_ONCE(a);
 	BUILD_BUG_ON(MAX <= 1); /* Order load from a with store to b. */
 	if (q % MAX) {
+		barrier();
 		ACCESS_ONCE(b) = p;
 		do_something();
 	} else {
+		barrier();
 		ACCESS_ONCE(b) = p;
 		do_something_else();
 	}
-- 
1.9.1

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