From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E862C282C4 for ; Tue, 12 Feb 2019 19:24:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D5E372190B for ; Tue, 12 Feb 2019 19:24:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732325AbfBLTYN (ORCPT ); Tue, 12 Feb 2019 14:24:13 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:59372 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729466AbfBLTYM (ORCPT ); Tue, 12 Feb 2019 14:24:12 -0500 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x1CJEHRq023246 for ; Tue, 12 Feb 2019 14:24:11 -0500 Received: from e16.ny.us.ibm.com (e16.ny.us.ibm.com [129.33.205.206]) by mx0b-001b2d01.pphosted.com with ESMTP id 2qm3bfac94-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 12 Feb 2019 14:24:10 -0500 Received: from localhost by e16.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 12 Feb 2019 19:24:06 -0000 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x1CJO56p14024856 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 12 Feb 2019 19:24:05 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5EC52B2066; Tue, 12 Feb 2019 19:24:05 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4006BB2064; Tue, 12 Feb 2019 19:24:05 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.41]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 12 Feb 2019 19:24:05 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 8C2B816C63F0; Tue, 12 Feb 2019 11:24:05 -0800 (PST) Date: Tue, 12 Feb 2019 11:24:05 -0800 From: "Paul E. McKenney" To: Will Deacon Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Benjamin Herrenschmidt , Arnd Bergmann , Peter Zijlstra , Andrea Parri , Daniel Lustig , David Howells , Alan Stern , Linus Torvalds Subject: Re: [RFC PATCH] docs/memory-barriers.txt: Rewrite "KERNEL I/O BARRIER EFFECTS" section Reply-To: paulmck@linux.ibm.com References: <20190211172948.3322-1-will.deacon@arm.com> <20190211202218.GQ4240@linux.ibm.com> <20190212184354.GC20961@fuggles.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190212184354.GC20961@fuggles.cambridge.arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 19021219-0072-0000-0000-000003F8F097 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010584; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000279; SDB=6.01160107; UDB=6.00605458; IPR=6.00940657; MB=3.00025549; MTD=3.00000008; XFM=3.00000015; UTC=2019-02-12 19:24:09 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19021219-0073-0000-0000-00004B28F309 Message-Id: <20190212192405.GU4240@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-02-12_09:,, 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 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902120135 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 12, 2019 at 06:43:54PM +0000, Will Deacon wrote: > On Mon, Feb 11, 2019 at 12:22:18PM -0800, Paul E. McKenney wrote: > > On Mon, Feb 11, 2019 at 05:29:48PM +0000, Will Deacon wrote: > > > The "KERNEL I/O BARRIER EFFECTS" section of memory-barriers.txt is vague, > > > x86-centric, out-of-date, incomplete and demonstrably incorrect in places. > > > This is largely because I/O ordering is a horrible can of worms, but also > > > because the document has stagnated as our understanding has evolved. > > > > > > Attempt to address some of that, by rewriting the section based on > > > recent(-ish) discussions with Arnd, BenH and others. Maybe one day we'll > > > find a way to formalise this stuff, but for now let's at least try to > > > make the English easier to understand. > > > > > > Cc: "Paul E. McKenney" > > > Cc: Benjamin Herrenschmidt > > > Cc: Arnd Bergmann > > > Cc: Peter Zijlstra > > > Cc: Andrea Parri > > > Cc: Daniel Lustig > > > Cc: David Howells > > > Cc: Alan Stern > > > cc: Linus Torvalds > > > Signed-off-by: Will Deacon > > > > Hello, Will, > > > > The intent is to replace commit 3f305018dcf3 ("docs/memory-barriers.txt: > > Enforce heavy ordering for port I/O accesses"), correct? Either way is > > fine, just guessing based on the conflicts when applying this one. ;-) > > Yup, I decided to abandon the old patch: > > http://lkml.kernel.org/r/20190211153043.GC32385@fuggles.cambridge.arm.com Got it, and thank you for the reminder! Thanx, Paul