x86/gup: Replace ACCESS_ONCE with READ_ONCE
authorChristian Borntraeger <borntraeger@de.ibm.com>
Fri, 21 Nov 2014 15:29:40 +0000 (16:29 +0100)
committerChristian Borntraeger <borntraeger@de.ibm.com>
Thu, 18 Dec 2014 08:54:38 +0000 (09:54 +0100)
commit14cf3d977b80f5e355f8ac7547cf1b9ff9fb3e09
tree26dff7a852d6e5c5f48c55404662c67cd94c604b
parent4f9d1382e6f80dcfa891b2c02d5a35c53be485f1
x86/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>
arch/x86/mm/gup.c