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Message-Id: <1416919117-50652-7-git-send-email-borntraeger@de.ibm.com>
Date: Tue, 25 Nov 2014 13:38:33 +0100
From: Christian Borntraeger <borntraeger@...ibm.com>
To: linux-kernel@...r.kernel.org
Cc: "linux-arch@...r.kernel.org, linux-mips@...ux-mips.org, linux-x86_64@...r.kernel.org, linux-s390"@vger.kernel.org,
Paolo Bonzini <pbonzini@...hat.com>,
paulmck@...ux.vnet.ibm.com, mingo@...nel.org,
torvalds@...ux-foundation.org,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Alexei Starovoitov <alexei.starovoitov@...il.com>,
David Howells <dhowells@...hat.com>,
Russell King <linux@....linux.org.uk>,
Christian Borntraeger <borntraeger@...ibm.com>
Subject: [PATCHv2 06/10] mips: Replace ACCESS_ONCE in gup 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@...ibm.com>
---
arch/mips/mm/gup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
index 06ce17c..8aa50e3 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
}
--
1.9.3
--
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