From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-x22f.google.com (mail-ob0-x22f.google.com [IPv6:2607:f8b0:4003:c01::22f]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 5639C1A089E for ; Thu, 17 Sep 2015 01:50:12 +1000 (AEST) Received: by obqa2 with SMTP id a2so152859108obq.3 for ; Wed, 16 Sep 2015 08:50:10 -0700 (PDT) From: Boqun Feng To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: Peter Zijlstra , Ingo Molnar , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Thomas Gleixner , Will Deacon , "Paul E. McKenney" , Waiman Long , Boqun Feng Subject: [RFC v2 2/7] atomics: Allow architectures to define their own __atomic_op_* helpers Date: Wed, 16 Sep 2015 23:49:30 +0800 Message-Id: <1442418575-12297-3-git-send-email-boqun.feng@gmail.com> In-Reply-To: <1442418575-12297-1-git-send-email-boqun.feng@gmail.com> References: <1442418575-12297-1-git-send-email-boqun.feng@gmail.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 --- include/linux/atomic.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/include/linux/atomic.h b/include/linux/atomic.h index 00a5763..590c023 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 -- 2.5.1