arm/spinlock: 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 spinlock 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>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/arm/include/asm/spinlock.h b/arch/arm/include/asm/spinlock.h
index ac4bfae26702..0fa418463f49 100644
--- a/arch/arm/include/asm/spinlock.h
+++ b/arch/arm/include/asm/spinlock.h
@@ -120,12 +120,12 @@ static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
 
 static inline int arch_spin_is_locked(arch_spinlock_t *lock)
 {
-        return !arch_spin_value_unlocked(ACCESS_ONCE(*lock));
+        return !arch_spin_value_unlocked(READ_ONCE(*lock));
 }
 
 static inline int arch_spin_is_contended(arch_spinlock_t *lock)
 {
-        struct __raw_tickets tickets = ACCESS_ONCE(lock->tickets);
+        struct __raw_tickets tickets = READ_ONCE(lock->tickets);
         return (tickets.next - tickets.owner) > 1;
 }
 #define arch_spin_is_contended  arch_spin_is_contended