Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932575AbdDQXs0 (ORCPT ); Mon, 17 Apr 2017 19:48:26 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:40831 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755704AbdDQXpk (ORCPT ); Mon, 17 Apr 2017 19:45:40 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" , Will Deacon , Boqun Feng , Benjamin Herrenschmidt , Paul Mackerras , Subject: [PATCH v2 tip/core/rcu 02/39] rcu: Make arch select smp_mb__after_unlock_lock() strength Date: Mon, 17 Apr 2017 16:44:49 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20170417234452.GB19013@linux.vnet.ibm.com> References: <20170417234452.GB19013@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17041723-0056-0000-0000-00000340C7C9 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006935; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000208; SDB=6.00848869; UDB=6.00419100; IPR=6.00627510; BA=6.00005292; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015073; XFM=3.00000013; UTC=2017-04-17 23:45:37 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17041723-0057-0000-0000-00000776D809 Message-Id: <1492472726-3841-2-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-04-17_20:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1702020001 definitions=main-1704170205 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2458 Lines: 70 The definition of smp_mb__after_unlock_lock() is currently smp_mb() for CONFIG_PPC and a no-op otherwise. It would be better to instead provide an architecture-selectable Kconfig option, and select the strength of smp_mb__after_unlock_lock() based on that option. This commit therefore creates ARCH_WEAK_RELEASE_ACQUIRE, has PPC select it, and bases the definition of smp_mb__after_unlock_lock() on this new ARCH_WEAK_RELEASE_ACQUIRE Kconfig option. Reported-by: Ingo Molnar Signed-off-by: Paul E. McKenney Cc: Peter Zijlstra Cc: Will Deacon Cc: Boqun Feng Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Acked-by: Michael Ellerman Cc: --- arch/Kconfig | 3 +++ arch/powerpc/Kconfig | 1 + include/linux/rcupdate.h | 6 +++--- 3 files changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index cd211a14a88f..adefaf344239 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -320,6 +320,9 @@ config HAVE_CMPXCHG_LOCAL config HAVE_CMPXCHG_DOUBLE bool +config ARCH_WEAK_RELEASE_ACQUIRE + bool + config ARCH_WANT_IPC_PARSE_VERSION bool diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 97a8bc8a095c..7a5c9b764cd2 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -99,6 +99,7 @@ config PPC select ARCH_USE_BUILTIN_BSWAP select ARCH_USE_CMPXCHG_LOCKREF if PPC64 select ARCH_WANT_IPC_PARSE_VERSION + select ARCH_WEAK_RELEASE_ACQUIRE select BINFMT_ELF select BUILDTIME_EXTABLE_SORT select CLONE_BACKWARDS diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index de88b33c0974..e6146d0074f8 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -1127,11 +1127,11 @@ do { \ * if the UNLOCK and LOCK are executed by the same CPU or if the * UNLOCK and LOCK operate on the same lock variable. */ -#ifdef CONFIG_PPC +#ifdef CONFIG_ARCH_WEAK_RELEASE_ACQUIRE #define smp_mb__after_unlock_lock() smp_mb() /* Full ordering for lock. */ -#else /* #ifdef CONFIG_PPC */ +#else /* #ifdef CONFIG_ARCH_WEAK_RELEASE_ACQUIRE */ #define smp_mb__after_unlock_lock() do { } while (0) -#endif /* #else #ifdef CONFIG_PPC */ +#endif /* #else #ifdef CONFIG_ARCH_WEAK_RELEASE_ACQUIRE */ #endif /* __LINUX_RCUPDATE_H */ -- 2.5.2