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x86/gup: Replace ACCESS_ONCE with READ_ONCE

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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>
This commit is contained in:
Christian Borntraeger 2014-11-21 16:29:40 +01:00
parent 4f9d1382e6
commit 14cf3d977b
1 changed files with 1 additions and 1 deletions
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2
arch/x86/mm/gup.c
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@ -15,7 +15,7 @@
static inline pte_t gup_get_pte(pte_t *ptep)
{
#ifndef CONFIG_X86_PAE
return ACCESS_ONCE(*ptep);
return READ_ONCE(*ptep);
#else
/*
* With get_user_pages_fast, we walk down the pagetables without taking