From patchwork Wed Nov 2 20:30:22 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 4910 Return-Path: X-Original-To: patchwork@peony.canonical.com Delivered-To: patchwork@peony.canonical.com Received: from fiordland.canonical.com (fiordland.canonical.com [91.189.94.145]) by peony.canonical.com (Postfix) with ESMTP id 1E8A423DC3 for ; Wed, 2 Nov 2011 20:31:56 +0000 (UTC) Received: from mail-fx0-f52.google.com (mail-fx0-f52.google.com [209.85.161.52]) by fiordland.canonical.com (Postfix) with ESMTP id 0D1AFA18670 for ; Wed, 2 Nov 2011 20:31:56 +0000 (UTC) Received: by mail-fx0-f52.google.com with SMTP id n26so1195523faa.11 for ; Wed, 02 Nov 2011 13:31:56 -0700 (PDT) Received: by 10.223.62.209 with SMTP id y17mr10823887fah.7.1320265915660; Wed, 02 Nov 2011 13:31:55 -0700 (PDT) X-Forwarded-To: linaro-patchwork@canonical.com X-Forwarded-For: patch@linaro.org linaro-patchwork@canonical.com Delivered-To: patches@linaro.org Received: by 10.152.14.103 with SMTP id o7cs64047lac; Wed, 2 Nov 2011 13:31:55 -0700 (PDT) Received: by 10.52.35.147 with SMTP id h19mr6268511vdj.38.1320265913589; Wed, 02 Nov 2011 13:31:53 -0700 (PDT) Received: from e7.ny.us.ibm.com (e7.ny.us.ibm.com. [32.97.182.137]) by mx.google.com with ESMTPS id a11si856292vcw.37.2011.11.02.13.31.53 (version=TLSv1/SSLv3 cipher=OTHER); Wed, 02 Nov 2011 13:31:53 -0700 (PDT) Received-SPF: pass (google.com: domain of paulmck@linux.vnet.ibm.com designates 32.97.182.137 as permitted sender) client-ip=32.97.182.137; Authentication-Results: mx.google.com; spf=pass (google.com: domain of paulmck@linux.vnet.ibm.com designates 32.97.182.137 as permitted sender) smtp.mail=paulmck@linux.vnet.ibm.com Received: from /spool/local by e7.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 2 Nov 2011 16:31:26 -0400 Received: from d01relay07.pok.ibm.com ([9.56.227.147]) by e7.ny.us.ibm.com ([192.168.1.107]) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Wed, 2 Nov 2011 16:31:00 -0400 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay07.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id pA2KUwub2506874 for ; Wed, 2 Nov 2011 16:30:58 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id pA2KUqjN029830 for ; Wed, 2 Nov 2011 16:30:58 -0400 Received: from paulmck-ThinkPad-W500 (sig-9-49-130-61.mts.ibm.com [9.49.130.61]) by d01av04.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id pA2KUpp7029757; Wed, 2 Nov 2011 16:30:52 -0400 Received: by paulmck-ThinkPad-W500 (Postfix, from userid 1000) id 9F9E5EA759; Wed, 2 Nov 2011 13:30:51 -0700 (PDT) From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, patches@linaro.org, "Paul E. McKenney" , anton@samba.org, benh@kernel.crashing.org, paulus@samba.org Subject: [PATCH RFC tip/core/rcu 01/28] powerpc: Strengthen value-returning-atomics memory barriers Date: Wed, 2 Nov 2011 13:30:22 -0700 Message-Id: <1320265849-5744-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.3.2 In-Reply-To: <20111102203017.GA3830@linux.vnet.ibm.com> References: <20111102203017.GA3830@linux.vnet.ibm.com> x-cbid: 11110220-5806-0000-0000-000000F809DC The trailing isync/lwsync in PowerPC value-returning atomics needs to be a sync in order to provide the required ordering properties. The leading lwsync/eieio can remain, as the remainder of the required ordering guarantees are provided by the atomic instructions: Any reordering will cause the stwcx to fail, which will result in a retry. This commit provides the needed adjustment. Signed-off-by: Paul E. McKenney Cc: anton@samba.org Cc: benh@kernel.crashing.org Cc: paulus@samba.org --- arch/powerpc/include/asm/synch.h | 6 +----- 1 files changed, 1 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/include/asm/synch.h b/arch/powerpc/include/asm/synch.h index d7cab44..4d97fbe 100644 --- a/arch/powerpc/include/asm/synch.h +++ b/arch/powerpc/include/asm/synch.h @@ -37,11 +37,7 @@ static inline void isync(void) #endif #ifdef CONFIG_SMP -#define __PPC_ACQUIRE_BARRIER \ - START_LWSYNC_SECTION(97); \ - isync; \ - MAKE_LWSYNC_SECTION_ENTRY(97, __lwsync_fixup); -#define PPC_ACQUIRE_BARRIER "\n" stringify_in_c(__PPC_ACQUIRE_BARRIER) +#define PPC_ACQUIRE_BARRIER "\n" stringify_in_c(sync;) #define PPC_RELEASE_BARRIER stringify_in_c(LWSYNC) "\n" #else #define PPC_ACQUIRE_BARRIER