From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1165082AbeBOXcu (ORCPT ); Thu, 15 Feb 2018 18:32:50 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:44464 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1163785AbeBOXcs (ORCPT ); Thu, 15 Feb 2018 18:32:48 -0500 Date: Thu, 15 Feb 2018 15:32:59 -0800 From: "Paul E. McKenney" To: Andrea Parri Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, stern@rowland.harvard.edu, will.deacon@arm.com, peterz@infradead.org, boqun.feng@gmail.com, npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk, luc.maranget@inria.fr, akiyks@gmail.com Subject: Re: [PATCH RFC tip/lkmm 08/10] EXP Remove understore from smp_mb__before_atomic() workings Reply-To: paulmck@linux.vnet.ibm.com References: <20180209141832.GA17505@linux.vnet.ibm.com> <1518186031-17997-8-git-send-email-paulmck@linux.vnet.ibm.com> <20180215223009.GA5460@andrea> <20180215224937.GD3617@linux.vnet.ibm.com> <20180215231958.GA7422@andrea> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180215231958.GA7422@andrea> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18021523-0044-0000-0000-000003E4FF26 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008539; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000253; SDB=6.00990289; UDB=6.00502910; IPR=6.00769637; MB=3.00019576; MTD=3.00000008; XFM=3.00000015; UTC=2018-02-15 23:32:44 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18021523-0045-0000-0000-000008150062 Message-Id: <20180215233259.GE3617@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-15_11:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1802150279 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 16, 2018 at 12:19:58AM +0100, Andrea Parri wrote: > On Thu, Feb 15, 2018 at 02:49:37PM -0800, Paul E. McKenney wrote: > > On Thu, Feb 15, 2018 at 11:30:09PM +0100, Andrea Parri wrote: > > > On Fri, Feb 09, 2018 at 06:20:29AM -0800, Paul E. McKenney wrote: > > > > Signed-off-by: Paul E. McKenney > > > > > > nit: s/understore/underscore (a very understandable lapsus, BTW ;-) > > > > ;-) > > > > Will fix when squashing. > > > > > According to the cover letter, patches 8-10 of this series are intended > > > to be squashed together; it could be useful to add a description then: > > > the motivation for these changes might appear "trivial" today; months/ > > > years from now? mmh, I can't put my finger on it ;-) > > > > Assuming we keep these patches, agreed. Something like this for the > > aggregated single commit, perhaps: > > > > tools/memory-model: Convert underscores to hyphens > > > > Typical cat-language code uses hyphens for word separators in > > identifiers, but several LKMM identifiers use underscores instead. > > This commit therefore converts the underscores in the .bell and > > .cat files for smp_mb__before_atomic(), smp_mb__after_atomic(), > > and smp_mb__after_spinlock() to hyphens. > > > > > IMO, this descrition should also mention why this solution "is the way > > > to go" (e.g., compare with the solution recently implemented by Akira). > > > > You lost me here. Or are you asking for a commit log similar to that > > provided by Akira for his forward-port of Alan's unrelated patch? If > > so, please see above. > > I was mainly thinking "but rb_dep..."; or you're also planning to > rename this annotation and, maybe, the "rb-dep" relation (in order > to avoid the conflict)? The rb_dep relation goes away completely once we catch LKMM up with the recent changes that remove smp_read_barrier_depends() from the core kernel. So my current thought is hold back the "_"->"-" commit until that catch-up happens. Thanx, Paul > Andrea > > > > > > Thanx, Paul > > > > > Andrea > > > > > > > > > > --- > > > > tools/memory-model/linux-kernel.bell | 2 +- > > > > tools/memory-model/linux-kernel.cat | 2 +- > > > > tools/memory-model/linux-kernel.def | 2 +- > > > > 3 files changed, 3 insertions(+), 3 deletions(-) > > > > > > > > diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell > > > > index b984bbda01a5..558bbef9e08a 100644 > > > > --- a/tools/memory-model/linux-kernel.bell > > > > +++ b/tools/memory-model/linux-kernel.bell > > > > @@ -28,7 +28,7 @@ enum Barriers = 'wmb (*smp_wmb*) || > > > > 'rcu-lock (*rcu_read_lock*) || > > > > 'rcu-unlock (*rcu_read_unlock*) || > > > > 'sync-rcu (*synchronize_rcu*) || > > > > - 'before_atomic (*smp_mb__before_atomic*) || > > > > + 'before-atomic (*smp_mb__before_atomic*) || > > > > 'after_atomic (*smp_mb__after_atomic*) || > > > > 'after_spinlock (*smp_mb__after_spinlock*) > > > > instructions F[Barriers] > > > > diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat > > > > index babe2b3b0bb3..31c08a44c088 100644 > > > > --- a/tools/memory-model/linux-kernel.cat > > > > +++ b/tools/memory-model/linux-kernel.cat > > > > @@ -29,7 +29,7 @@ let rb-dep = [R] ; fencerel(Rb_dep) ; [R] > > > > let rmb = [R \ Noreturn] ; fencerel(Rmb) ; [R \ Noreturn] > > > > let wmb = [W] ; fencerel(Wmb) ; [W] > > > > let mb = ([M] ; fencerel(Mb) ; [M]) | > > > > - ([M] ; fencerel(Before_atomic) ; [RMW] ; po? ; [M]) | > > > > + ([M] ; fencerel(Before-atomic) ; [RMW] ; po? ; [M]) | > > > > ([M] ; po? ; [RMW] ; fencerel(After_atomic) ; [M]) | > > > > ([M] ; po? ; [LKW] ; fencerel(After_spinlock) ; [M]) > > > > let gp = po ; [Sync-rcu] ; po? > > > > diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def > > > > index a397387f77cc..ff4b756f4a44 100644 > > > > --- a/tools/memory-model/linux-kernel.def > > > > +++ b/tools/memory-model/linux-kernel.def > > > > @@ -21,7 +21,7 @@ smp_mb() { __fence{mb} ; } > > > > smp_rmb() { __fence{rmb} ; } > > > > smp_wmb() { __fence{wmb} ; } > > > > smp_read_barrier_depends() { __fence{rb_dep}; } > > > > -smp_mb__before_atomic() { __fence{before_atomic} ; } > > > > +smp_mb__before_atomic() { __fence{before-atomic} ; } > > > > smp_mb__after_atomic() { __fence{after_atomic} ; } > > > > smp_mb__after_spinlock() { __fence{after_spinlock} ; } > > > > > > > > -- > > > > 2.5.2 > > > > > > > > > >