On Wed, Dec 03, 2014 at 11:30:18PM +0100, Christian Borntraeger wrote: > 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@xxxxxxxxxx> Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> > --- > arch/arm64/include/asm/spinlock.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h > index c45b7b1..cee1287 100644 > --- a/arch/arm64/include/asm/spinlock.h > +++ b/arch/arm64/include/asm/spinlock.h > @@ -99,12 +99,12 @@ 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) > { > - arch_spinlock_t lockval = ACCESS_ONCE(*lock); > + arch_spinlock_t lockval = READ_ONCE(*lock); > return (lockval.next - lockval.owner) > 1; > } > #define arch_spin_is_contended arch_spin_is_contended > -- > 1.9.3 > -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
