From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH] doc: Replace smp_cond_acquire() with smp_cond_load_acquire() Date: Wed, 11 Jul 2018 08:38:40 -0700 Message-ID: <20180711153840.GS3593@linux.vnet.ibm.com> References: <1531216943-6382-1-git-send-email-andrea.parri@amarulasolutions.com> <1531314530-11624-1-git-send-email-andrea.parri@amarulasolutions.com> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1531314530-11624-1-git-send-email-andrea.parri@amarulasolutions.com> Sender: linux-kernel-owner@vger.kernel.org To: Andrea Parri Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, Alan Stern , Will Deacon , Peter Zijlstra , Boqun Feng , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , Akira Yokosawa , Daniel Lustig , Jonathan Corbet List-Id: linux-arch.vger.kernel.org On Wed, Jul 11, 2018 at 03:08:50PM +0200, Andrea Parri wrote: > Amend commit 1f03e8d2919270 ("locking/barriers: Replace smp_cond_acquire() > with smp_cond_load_acquire()") by updating the documentation accordingly. > Also remove some obsolete information related to the implementation. > > Signed-off-by: Andrea Parri > Cc: Alan Stern > Cc: Will Deacon > Cc: Peter Zijlstra > Cc: Boqun Feng > Cc: Nicholas Piggin > Cc: David Howells > Cc: Jade Alglave > Cc: Luc Maranget > Cc: "Paul E. McKenney" > Cc: Akira Yokosawa > Cc: Daniel Lustig > Cc: Jonathan Corbet > --- > Documentation/memory-barriers.txt | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) I have queued this for further review, thank you! Just to confirm, the reason that the old passage was obsolete is because ARMv8 implements smp_cond_load_acquire() as a straight acquire load, correct? Thanx, Paul > diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt > index 0d8d7ef131e9a..c1d913944ad8b 100644 > --- a/Documentation/memory-barriers.txt > +++ b/Documentation/memory-barriers.txt > @@ -471,8 +471,7 @@ And a couple of implicit varieties: > operations after the ACQUIRE operation will appear to happen after the > ACQUIRE operation with respect to the other components of the system. > ACQUIRE operations include LOCK operations and both smp_load_acquire() > - and smp_cond_acquire() operations. The later builds the necessary ACQUIRE > - semantics from relying on a control dependency and smp_rmb(). > + and smp_cond_load_acquire() operations. > > Memory operations that occur before an ACQUIRE operation may appear to > happen after it completes. > -- > 2.7.4 > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:52264 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732587AbeGKPlW (ORCPT ); Wed, 11 Jul 2018 11:41:22 -0400 Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w6BFY53d061138 for ; Wed, 11 Jul 2018 11:36:28 -0400 Received: from e16.ny.us.ibm.com (e16.ny.us.ibm.com [129.33.205.206]) by mx0a-001b2d01.pphosted.com with ESMTP id 2k5k8548yy-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 11 Jul 2018 11:36:28 -0400 Received: from localhost by e16.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 11 Jul 2018 11:36:27 -0400 Date: Wed, 11 Jul 2018 08:38:40 -0700 From: "Paul E. McKenney" Subject: Re: [PATCH] doc: Replace smp_cond_acquire() with smp_cond_load_acquire() Reply-To: paulmck@linux.vnet.ibm.com References: <1531216943-6382-1-git-send-email-andrea.parri@amarulasolutions.com> <1531314530-11624-1-git-send-email-andrea.parri@amarulasolutions.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1531314530-11624-1-git-send-email-andrea.parri@amarulasolutions.com> Message-ID: <20180711153840.GS3593@linux.vnet.ibm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Andrea Parri Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, Alan Stern , Will Deacon , Peter Zijlstra , Boqun Feng , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , Akira Yokosawa , Daniel Lustig , Jonathan Corbet Message-ID: <20180711153840.rwP1ER64exS0OVwodKKI9ieBODFEyTWaP7XovDHuiZs@z> On Wed, Jul 11, 2018 at 03:08:50PM +0200, Andrea Parri wrote: > Amend commit 1f03e8d2919270 ("locking/barriers: Replace smp_cond_acquire() > with smp_cond_load_acquire()") by updating the documentation accordingly. > Also remove some obsolete information related to the implementation. > > Signed-off-by: Andrea Parri > Cc: Alan Stern > Cc: Will Deacon > Cc: Peter Zijlstra > Cc: Boqun Feng > Cc: Nicholas Piggin > Cc: David Howells > Cc: Jade Alglave > Cc: Luc Maranget > Cc: "Paul E. McKenney" > Cc: Akira Yokosawa > Cc: Daniel Lustig > Cc: Jonathan Corbet > --- > Documentation/memory-barriers.txt | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) I have queued this for further review, thank you! Just to confirm, the reason that the old passage was obsolete is because ARMv8 implements smp_cond_load_acquire() as a straight acquire load, correct? Thanx, Paul > diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt > index 0d8d7ef131e9a..c1d913944ad8b 100644 > --- a/Documentation/memory-barriers.txt > +++ b/Documentation/memory-barriers.txt > @@ -471,8 +471,7 @@ And a couple of implicit varieties: > operations after the ACQUIRE operation will appear to happen after the > ACQUIRE operation with respect to the other components of the system. > ACQUIRE operations include LOCK operations and both smp_load_acquire() > - and smp_cond_acquire() operations. The later builds the necessary ACQUIRE > - semantics from relying on a control dependency and smp_rmb(). > + and smp_cond_load_acquire() operations. > > Memory operations that occur before an ACQUIRE operation may appear to > happen after it completes. > -- > 2.7.4 >