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[192.157.208.129]) by smtp.gmail.com with ESMTPSA id r8sm3053871ioi.10.2015.08.27.19.48.49 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Aug 2015 19:48:50 -0700 (PDT) From: Boqun Feng To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [RFC 2/5] atomics: introduce arch_atomic_op_{acquire, release, fence} helpers Date: Fri, 28 Aug 2015 10:48:16 +0800 Message-Id: <1440730099-29133-3-git-send-email-boqun.feng@gmail.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1440730099-29133-1-git-send-email-boqun.feng@gmail.com> References: <1440730099-29133-1-git-send-email-boqun.feng@gmail.com> X-Mailman-Approved-At: Fri, 28 Aug 2015 16:26:40 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Waiman Long , Peter Zijlstra , Boqun Feng , Will Deacon , Paul Mackerras , Thomas Gleixner , "Paul E. McKenney" , Ingo Molnar MIME-Version: 1.0 Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Some architectures may have their special barriers for acquire, release and fence semantics, general memory barriers(smp_mb__*_atomic()) in __atomic_op_*() may be too strong, so arch_atomic_op_*() helpers are introduced for architectures to provide their own version helpers to build different variants based on _relaxed variants. Signed-off-by: Boqun Feng --- include/linux/atomic.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/include/linux/atomic.h b/include/linux/atomic.h index 00a5763..622255b 100644 --- a/include/linux/atomic.h +++ b/include/linux/atomic.h @@ -34,20 +34,33 @@ * 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 arch_atomic_op_* and use the same framework for building + * variants */ +#ifndef arch_atomic_op_acquire #define __atomic_op_acquire(op, args...) \ ({ \ typeof(op##_relaxed(args)) __ret = op##_relaxed(args); \ smp_mb__after_atomic(); \ __ret; \ }) +#else +#define __atomic_op_acquire arch_atomic_op_acquire +#endif +#ifndef arch_atomic_op_release #define __atomic_op_release(op, args...) \ ({ \ smp_mb__before_atomic(); \ op##_relaxed(args); \ }) +#else +#define __atomic_op_release arch_atomic_op_release +#endif +#ifndef arch_atomic_op_fence #define __atomic_op_fence(op, args...) \ ({ \ typeof(op##_relaxed(args)) __ret; \ @@ -56,6 +69,9 @@ smp_mb__after_atomic(); \ __ret; \ }) +#else +#define __atomic_op_fence arch_atomic_op_fence +#endif /* atomic_add_return_relaxed */ #ifndef atomic_add_return_relaxed