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Commit e1ab7f39 authored by Boqun Feng's avatar Boqun Feng Committed by Michael Ellerman
Browse files

atomics: Allow architectures to define their own __atomic_op_* helpers 



Some architectures may have their special barriers for acquire, release
and fence semantics, so that general memory barriers(smp_mb__*_atomic())
in the default __atomic_op_*() may be too strong, so allow architectures
to define their own helpers which can overwrite the default helpers.

Signed-off-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 78c1cffd

include/linux/atomic.h

+10 −0
Original line number Original line Diff line number Diff line
@@ -34,20 +34,29 @@ 
 * The idea here is to build acquire/release variants by adding explicit

 * The idea here is to build acquire/release variants by adding explicit

 * barriers on top of the relaxed variant. In the case where the relaxed

 * barriers on top of the relaxed variant. In the case where the relaxed

 * variant is already fully ordered, no additional barriers are needed.

 * variant is already fully ordered, no additional barriers are needed.

 *

 * Besides, if an arch has a special barrier for acquire/release, it could

 * implement its own __atomic_op_* and use the same framework for building

 * variants

 */

 */

#ifndef __atomic_op_acquire

#define __atomic_op_acquire(op, args...)				\

#define __atomic_op_acquire(op, args...)				\

({									\

({									\

	typeof(op##_relaxed(args)) __ret  = op##_relaxed(args);		\

	typeof(op##_relaxed(args)) __ret  = op##_relaxed(args);		\

	smp_mb__after_atomic();						\

	smp_mb__after_atomic();						\

	__ret;								\

	__ret;								\

})

})

#endif





#ifndef __atomic_op_release

#define __atomic_op_release(op, args...)				\

#define __atomic_op_release(op, args...)				\

({									\

({									\

	smp_mb__before_atomic();					\

	smp_mb__before_atomic();					\

	op##_relaxed(args);						\

	op##_relaxed(args);						\

})

})

#endif





#ifndef __atomic_op_fence

#define __atomic_op_fence(op, args...)					\

#define __atomic_op_fence(op, args...)					\

({									\

({									\

	typeof(op##_relaxed(args)) __ret;				\

	typeof(op##_relaxed(args)) __ret;				\
@@ -56,6 +65,7 @@ 
	smp_mb__after_atomic();						\

	smp_mb__after_atomic();						\

	__ret;								\

	__ret;								\

})

})

#endif





/* atomic_add_return_relaxed */

/* atomic_add_return_relaxed */

#ifndef atomic_add_return_relaxed

#ifndef atomic_add_return_relaxed