From 6b31f12813286d715c0a93065dc7620df3fdb2a0 Mon Sep 17 00:00:00 2001 From: Boqun Feng <boqun.feng@gmail.com> Date: Tue, 15 Dec 2015 22:24:14 +0800 Subject: [PATCH] atomics: Allow architectures to define their own __atomic_op_* helpers BugLink: http://bugs.launchpad.net/bugs/1556096 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: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> (cherry picked from commit e1ab7f39d7e0dbfbdefe148be3ae4ee121e47ecc) Signed-off-by: Tim Gardner <tim.gardner@canonical.com> --- include/linux/atomic.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/include/linux/atomic.h b/include/linux/atomic.h index 301de78d65f7..5f3ee5a60a81 100644 --- a/include/linux/atomic.h +++ b/include/linux/atomic.h @@ -34,20 +34,29 @@ * 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 * 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...) \ ({ \ typeof(op##_relaxed(args)) __ret = op##_relaxed(args); \ smp_mb__after_atomic(); \ __ret; \ }) +#endif +#ifndef __atomic_op_release #define __atomic_op_release(op, args...) \ ({ \ smp_mb__before_atomic(); \ op##_relaxed(args); \ }) +#endif +#ifndef __atomic_op_fence #define __atomic_op_fence(op, args...) \ ({ \ typeof(op##_relaxed(args)) __ret; \ @@ -56,6 +65,7 @@ smp_mb__after_atomic(); \ __ret; \ }) +#endif /* atomic_add_return_relaxed */ #ifndef atomic_add_return_relaxed -- 2.30.9