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| author | Boqun Feng <boqun.feng@gmail.com> | 2015-12-15 22:24:14 +0800 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2016-02-18 00:11:02 +1100 |
| commit | e1ab7f39d7e0dbfbdefe148be3ae4ee121e47ecc (patch) | |
| tree | 136a0781bf5788d595c85b887deef198ccaae789 /include/linux/atomic.h | |
| parent | 78c1cffdab7e5fc316be7d6a076e51ec3a0210fc (diff) | |
| download | lwn-e1ab7f39d7e0dbfbdefe148be3ae4ee121e47ecc.tar.gz lwn-e1ab7f39d7e0dbfbdefe148be3ae4ee121e47ecc.zip | |
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: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'include/linux/atomic.h')
| -rw-r--r-- | include/linux/atomic.h | 10 |
1 files changed, 10 insertions, 0 deletions
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 |