From mboxrd@z Thu Jan 1 00:00:00 1970 From: "tip-bot for Michael S. Tsirkin" Subject: [tip:locking/core] locking/x86: Use mb() around clflush() Date: Fri, 29 Jan 2016 03:33:14 -0800 Message-ID: References: <1453921746-16178-5-git-send-email-mst@redhat.com> Reply-To: luto@amacapital.net, dvlasenk@redhat.com, bitbucket@online.de, oleg@redhat.com, len.brown@intel.com, torvalds@linux-foundation.org, peterz@infradead.org, tglx@linutronix.de, luto@kernel.org, akpm@linux-foundation.org, dbueso@suse.de, brgerst@gmail.com, mst@redhat.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, dave@stgolabs.net, bp@alien8.de, paulmck@linux.vnet.ibm.com, hpa@zytor.com, mingo@kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1453921746-16178-5-git-send-email-mst@redhat.com> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: linux-tip-commits@vger.kernel.org Cc: len.brown@intel.com, dave@stgolabs.net, dvlasenk@redhat.com, akpm@linux-foundation.org, mst@redhat.com, bitbucket@online.de, brgerst@gmail.com, dbueso@suse.de, oleg@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, peterz@infradead.org, luto@amacapital.net, bp@alien8.de, luto@kernel.org, hpa@zytor.com, tglx@linutronix.de, paulmck@linux.vnet.ibm.com, torvalds@linux-foundation.org, mingo@kernel.org List-Id: virtualization@lists.linuxfoundation.org Commit-ID: ca59809ff6d572ae58fc6bedf7500f5a60fdbd64 Gitweb: http://git.kernel.org/tip/ca59809ff6d572ae58fc6bedf7500f5a60fdbd64 Author: Michael S. Tsirkin AuthorDate: Thu, 28 Jan 2016 19:02:51 +0200 Committer: Ingo Molnar CommitDate: Fri, 29 Jan 2016 09:40:10 +0100 locking/x86: Use mb() around clflush() The following commit: f8e617f4582995f ("sched/idle/x86: Optimize unnecessary mwait_idle() resched IPIs") adds memory barriers around clflush(), but this seems wrong for UP since barrier() has no effect on clflush(). We really want MFENCE, so switch to mb() instead. Signed-off-by: Michael S. Tsirkin Acked-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Davidlohr Bueso Cc: Davidlohr Bueso Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Len Brown Cc: Linus Torvalds Cc: Mike Galbraith Cc: Oleg Nesterov Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: virtualization Link: http://lkml.kernel.org/r/1453921746-16178-5-git-send-email-mst@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/process.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 9f7c21c..9decee2 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -418,9 +418,9 @@ static void mwait_idle(void) if (!current_set_polling_and_test()) { trace_cpu_idle_rcuidle(1, smp_processor_id()); if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) { - smp_mb(); /* quirk */ + mb(); /* quirk */ clflush((void *)¤t_thread_info()->flags); - smp_mb(); /* quirk */ + mb(); /* quirk */ } __monitor((void *)¤t_thread_info()->flags, 0, 0); From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755822AbcA2Leh (ORCPT ); Fri, 29 Jan 2016 06:34:37 -0500 Received: from terminus.zytor.com ([198.137.202.10]:56420 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755151AbcA2Lef (ORCPT ); Fri, 29 Jan 2016 06:34:35 -0500 Date: Fri, 29 Jan 2016 03:33:14 -0800 From: "tip-bot for Michael S. Tsirkin" Message-ID: Cc: brgerst@gmail.com, mst@redhat.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, dave@stgolabs.net, bp@alien8.de, paulmck@linux.vnet.ibm.com, hpa@zytor.com, mingo@kernel.org, luto@amacapital.net, dvlasenk@redhat.com, oleg@redhat.com, bitbucket@online.de, len.brown@intel.com, torvalds@linux-foundation.org, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org, luto@kernel.org, dbueso@suse.de Reply-To: luto@amacapital.net, dvlasenk@redhat.com, bitbucket@online.de, oleg@redhat.com, len.brown@intel.com, torvalds@linux-foundation.org, peterz@infradead.org, tglx@linutronix.de, luto@kernel.org, akpm@linux-foundation.org, dbueso@suse.de, brgerst@gmail.com, mst@redhat.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, dave@stgolabs.net, bp@alien8.de, paulmck@linux.vnet.ibm.com, hpa@zytor.com, mingo@kernel.org In-Reply-To: <1453921746-16178-5-git-send-email-mst@redhat.com> References: <1453921746-16178-5-git-send-email-mst@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] locking/x86: Use mb() around clflush() Git-Commit-ID: ca59809ff6d572ae58fc6bedf7500f5a60fdbd64 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: ca59809ff6d572ae58fc6bedf7500f5a60fdbd64 Gitweb: http://git.kernel.org/tip/ca59809ff6d572ae58fc6bedf7500f5a60fdbd64 Author: Michael S. Tsirkin AuthorDate: Thu, 28 Jan 2016 19:02:51 +0200 Committer: Ingo Molnar CommitDate: Fri, 29 Jan 2016 09:40:10 +0100 locking/x86: Use mb() around clflush() The following commit: f8e617f4582995f ("sched/idle/x86: Optimize unnecessary mwait_idle() resched IPIs") adds memory barriers around clflush(), but this seems wrong for UP since barrier() has no effect on clflush(). We really want MFENCE, so switch to mb() instead. Signed-off-by: Michael S. Tsirkin Acked-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Davidlohr Bueso Cc: Davidlohr Bueso Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Len Brown Cc: Linus Torvalds Cc: Mike Galbraith Cc: Oleg Nesterov Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: virtualization Link: http://lkml.kernel.org/r/1453921746-16178-5-git-send-email-mst@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/process.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 9f7c21c..9decee2 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -418,9 +418,9 @@ static void mwait_idle(void) if (!current_set_polling_and_test()) { trace_cpu_idle_rcuidle(1, smp_processor_id()); if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) { - smp_mb(); /* quirk */ + mb(); /* quirk */ clflush((void *)¤t_thread_info()->flags); - smp_mb(); /* quirk */ + mb(); /* quirk */ } __monitor((void *)¤t_thread_info()->flags, 0, 0);