From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757615AbdJKQuO (ORCPT ); Wed, 11 Oct 2017 12:50:14 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:46610 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752351AbdJKQuM (ORCPT ); Wed, 11 Oct 2017 12:50:12 -0400 Date: Wed, 11 Oct 2017 09:50:04 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: David Howells , Will Deacon , linux-kernel@vger.kernel.org, mingo@kernel.org, torvalds@linux-foundation.org, mark.rutland@arm.com, linux-arch@vger.kernel.org, Jonathan Corbet , Alexander Kuleshov , dvyukov@google.com Subject: Re: [PATCH RFC tip/core/rcu 12/15] lib/assoc_array: Remove smp_read_barrier_depends() Reply-To: paulmck@linux.vnet.ibm.com References: <20171011122217.GD11106@arm.com> <20171010155042.GD3521@linux.vnet.ibm.com> <1507594969-8347-12-git-send-email-paulmck@linux.vnet.ibm.com> <20171010001951.GA6476@linux.vnet.ibm.com> <8079.1507628146@warthog.procyon.org.uk> <26455.1507724399@warthog.procyon.org.uk> <6309.1507735045@warthog.procyon.org.uk> <20171011155948.GE3521@linux.vnet.ibm.com> <20171011161220.zqkdhynxerrcmvdd@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171011161220.zqkdhynxerrcmvdd@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 17101116-0044-0000-0000-0000039E1883 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007878; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000236; SDB=6.00929666; UDB=6.00467927; IPR=6.00709937; BA=6.00005634; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00017492; XFM=3.00000015; UTC=2017-10-11 16:50:07 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17101116-0045-0000-0000-000007CD1A33 Message-Id: <20171011165004.GA14318@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-10-11_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1710110234 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 11, 2017 at 06:12:20PM +0200, Peter Zijlstra wrote: > On Wed, Oct 11, 2017 at 08:59:48AM -0700, Paul E. McKenney wrote: > > On Wed, Oct 11, 2017 at 04:17:25PM +0100, David Howells wrote: > > > I will, however, quibble with the appropriateness of the name READ_ONCE()... > > > I still think it's not sufficiently obvious that this is a barrier and the > > > barrier is after. Maybe READ_AND_BARRIER()? > > > > Linus was unhappy with READ_ONCE_CTRL() to tag control dependencies, but > > indicated that he might consider it if it helped code-analysis tools. > > Adding Dmitry Vyukov for his thoughts on whether tagging READ_ONCE() > > for dependencies would help. Me, I would suggest READ_ONCE_DEP(), but > > let's figure out if the bikeshed needs to be painted before arguing over > > the color. ;-) > > Count me one vote for the READ_ONCE() name. This is about dependent > reads, which are nothing special on anything except Alpha. Agreed, unless specially marking them makes it easier for tools to find bugs. In which case, we should definitely specially mark them. Thanx, Paul