linux-kernel - PATCH] s390: fix machine check handling

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Message-ID: <alpine.LFD.2.11.1411281544190.1648@denkbrett>
Date:	Fri, 28 Nov 2014 16:03:14 +0100 (CET)
From:	Sebastian Ott <sebott@...ux.vnet.ibm.com>
To:	Martin Schwidefsky <schwidefsky@...ibm.com>
cc:	Tejun Heo <tj@...nel.org>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Christoph Lameter <cl@...ux.com>, linux-kernel@...r.kernel.org
Subject: PATCH] s390: fix machine check handling

Hi,

would it be possible to have this one for 3.18 (if not, please add
Cc: stable@...r.kernel.org # v3.18)

Regards,
Sebastian

>8-----

>From ca198a6ff5766f19645104b7f8d621774524c4b4 Mon Sep 17 00:00:00 2001
From: Sebastian Ott <sebott@...ux.vnet.ibm.com>
Date: Fri, 28 Nov 2014 15:40:57 +0100
Subject: [PATCH] s390: fix machine check handling

Commit eb7e7d76 "s390: Replace __get_cpu_var uses" broke machine check
handling.

We copy machine check information from per-cpu to a stack variable for
local processing. Next we should zap the per-cpu variable, not the
stack variable.

Signed-off-by: Sebastian Ott <sebott@...ux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@...ibm.com>
---
 arch/s390/kernel/nmi.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
index dd1c24c..3f51cf4 100644
--- a/arch/s390/kernel/nmi.c
+++ b/arch/s390/kernel/nmi.c
@@ -54,12 +54,8 @@ void s390_handle_mcck(void)
 	 */
 	local_irq_save(flags);
 	local_mcck_disable();
-	/*
-	 * Ummm... Does this make sense at all? Copying the percpu struct
-	 * and then zapping it one statement later?
-	 */
-	memcpy(&mcck, this_cpu_ptr(&cpu_mcck), sizeof(mcck));
-	memset(&mcck, 0, sizeof(struct mcck_struct));
+	mcck = *this_cpu_ptr(&cpu_mcck);
+	memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
 	clear_cpu_flag(CIF_MCCK_PENDING);
 	local_mcck_enable();
 	local_irq_restore(flags);
-- 
1.8.4.2

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