From: Sebastian Ott <sebott@linux.vnet.ibm.com>
Date: Fri, 28 Nov 2014 14:40:57 +0000 (+0100)
Subject: s390: fix machine check handling
X-Git-Tag: firefly_0821_release~176^2~2803
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2cb4a18262fd0108cb8abd875710c59d0aa66f1d;p=firefly-linux-kernel-4.4.55.git

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@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
index dd1c24ceda50..3f51cf4e8f02 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);