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Message-Id: <1458602396-840-1-git-send-email-dave@stgolabs.net>
Date: Mon, 21 Mar 2016 16:19:56 -0700
From: Davidlohr Bueso <dave@...olabs.net>
To: bp@...en8.de, tony.luck@...el.com, mingo@...nel.org
Cc: linux-kernel@...r.kernel.org, dave@...olabs.net,
Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH -tip] x86/mce: Use atomic_inc_return barrier when starting monad sync
mce_start() has an explicit smp_wmb to serialize writes to
global_nwo and mce_callin. However, atomic_inc_return() implies
barriers on both sides of the call, as such simply rely on this
full smp barrier.
Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
arch/x86/kernel/cpu/mcheck/mce.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index f0c921b03e42..6b7039c166b8 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -830,9 +830,9 @@ static int mce_start(int *no_way_out)
atomic_add(*no_way_out, &global_nwo);
/*
- * global_nwo should be updated before mce_callin
+ * Rely on the implied barrier below, such that global_nwo
+ * is updated before mce_callin.
*/
- smp_wmb();
order = atomic_inc_return(&mce_callin);
/*
--
2.1.4
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