From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Fri, 21 Nov 2014 15:21:56 +0000 (+0100)
Subject: mips/gup: Replace ACCESS_ONCE with READ_ONCE
X-Git-Tag: v3.19-rc1~1^2~3
X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=4218091cb45f601b889cd032e39fe6878a426e70;p=~emulex%2Finfiniband.git

mips/gup: Replace ACCESS_ONCE with READ_ONCE

ACCESS_ONCE does not work reliably on non-scalar types. For
example gcc 4.6 and 4.7 might remove the volatile tag for such
accesses during the SRA (scalar replacement of aggregates) step
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145)

Change the gup code to replace ACCESS_ONCE with READ_ONCE.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---

diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
index 06ce17c2a90..8aa50e3f3fc 100644
--- a/arch/mips/mm/gup.c
+++ b/arch/mips/mm/gup.c
@@ -30,7 +30,7 @@ retry:
 
 	return pte;
 #else
-	return ACCESS_ONCE(*ptep);
+	return READ_ONCE(*ptep);
 #endif
 }