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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 32562C7618F for ; Wed, 17 Jul 2019 00:10:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0871621871 for ; Wed, 17 Jul 2019 00:10:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728714AbfGQAKM (ORCPT ); Tue, 16 Jul 2019 20:10:12 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:46304 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728597AbfGQAKM (ORCPT ); Tue, 16 Jul 2019 20:10:12 -0400 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x6H07KiH124292; Tue, 16 Jul 2019 20:08:00 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 2tsnmnejq4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 16 Jul 2019 20:07:59 -0400 Received: from m0098394.ppops.net (m0098394.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.27/8.16.0.27) with SMTP id x6H07OI6125043; Tue, 16 Jul 2019 20:07:59 -0400 Received: from ppma01wdc.us.ibm.com (fd.55.37a9.ip4.static.sl-reverse.com [169.55.85.253]) by mx0a-001b2d01.pphosted.com with ESMTP id 2tsnmnejpc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 16 Jul 2019 20:07:59 -0400 Received: from pps.filterd (ppma01wdc.us.ibm.com [127.0.0.1]) by ppma01wdc.us.ibm.com (8.16.0.27/8.16.0.27) with SMTP id x6H06MZU032508; Wed, 17 Jul 2019 00:07:57 GMT Received: from b01cxnp23033.gho.pok.ibm.com (b01cxnp23033.gho.pok.ibm.com [9.57.198.28]) by ppma01wdc.us.ibm.com with ESMTP id 2tq6x63b2y-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 17 Jul 2019 00:07:57 +0000 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x6H07vFM39780686 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 17 Jul 2019 00:07:57 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1A3E4B2065; Wed, 17 Jul 2019 00:07:57 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C0D28B206E; Wed, 17 Jul 2019 00:07:56 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.80.225.134]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Wed, 17 Jul 2019 00:07:56 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 30CFA16C8E9B; Tue, 16 Jul 2019 17:07:57 -0700 (PDT) Date: Tue, 16 Jul 2019 17:07:57 -0700 From: "Paul E. McKenney" To: Joel Fernandes Cc: linux-kernel@vger.kernel.org, Alexey Kuznetsov , Bjorn Helgaas , Borislav Petkov , c0d1n61at3@gmail.com, "David S. Miller" , edumazet@google.com, Greg Kroah-Hartman , Hideaki YOSHIFUJI , "H. Peter Anvin" , Ingo Molnar , Jonathan Corbet , Josh Triplett , keescook@chromium.org, kernel-hardening@lists.openwall.com, kernel-team@android.com, Lai Jiangshan , Len Brown , linux-acpi@vger.kernel.org, linux-doc@vger.kernel.org, linux-pci@vger.kernel.org, linux-pm@vger.kernel.org, Mathieu Desnoyers , neilb@suse.com, netdev@vger.kernel.org, Oleg Nesterov , Pavel Machek , peterz@infradead.org, "Rafael J. Wysocki" , Rasmus Villemoes , rcu@vger.kernel.org, Steven Rostedt , Tejun Heo , Thomas Gleixner , will@kernel.org, "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" Subject: Re: [PATCH 2/9] rcu: Add support for consolidated-RCU reader checking (v3) Message-ID: <20190717000757.GQ14271@linux.ibm.com> Reply-To: paulmck@linux.ibm.com References: <20190715143705.117908-1-joel@joelfernandes.org> <20190715143705.117908-3-joel@joelfernandes.org> <20190716183833.GD14271@linux.ibm.com> <20190716184649.GA130463@google.com> <20190716185303.GM14271@linux.ibm.com> <20190716220205.GB172157@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190716220205.GB172157@google.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-07-16_06:,, 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-1907160263 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Tue, Jul 16, 2019 at 06:02:05PM -0400, Joel Fernandes wrote: > On Tue, Jul 16, 2019 at 11:53:03AM -0700, Paul E. McKenney wrote: > [snip] > > > > A few more things below. > > > > > --- > > > > > include/linux/rculist.h | 28 ++++++++++++++++++++----- > > > > > include/linux/rcupdate.h | 7 +++++++ > > > > > kernel/rcu/Kconfig.debug | 11 ++++++++++ > > > > > kernel/rcu/update.c | 44 ++++++++++++++++++++++++---------------- > > > > > 4 files changed, 67 insertions(+), 23 deletions(-) > > > > > > > > > > diff --git a/include/linux/rculist.h b/include/linux/rculist.h > > > > > index e91ec9ddcd30..1048160625bb 100644 > > > > > --- a/include/linux/rculist.h > > > > > +++ b/include/linux/rculist.h > > > > > @@ -40,6 +40,20 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list) > > > > > */ > > > > > #define list_next_rcu(list) (*((struct list_head __rcu **)(&(list)->next))) > > > > > > > > > > +/* > > > > > + * Check during list traversal that we are within an RCU reader > > > > > + */ > > > > > + > > > > > +#ifdef CONFIG_PROVE_RCU_LIST > > > > > > > > This new Kconfig option is OK temporarily, but unless there is reason to > > > > fear malfunction that a few weeks of rcutorture, 0day, and -next won't > > > > find, it would be better to just use CONFIG_PROVE_RCU. The overall goal > > > > is to reduce the number of RCU knobs rather than grow them, must though > > > > history might lead one to believe otherwise. :-/ > > > > > > If you want, we can try to drop this option and just use PROVE_RCU however I > > > must say there may be several warnings that need to be fixed in a short > > > period of time (even a few weeks may be too short) considering the 1000+ > > > uses of RCU lists. > > Do many people other than me build with CONFIG_PROVE_RCU? If so, then > > that would be a good reason for a temporary CONFIG_PROVE_RCU_LIST, > > as in going away in a release or two once the warnings get fixed. > > PROVE_RCU is enabled by default with PROVE_LOCKING, so it is used quite > heavilty. > > > > But I don't mind dropping it and it may just accelerate the fixing up of all > > > callers. > > > > I will let you decide based on the above question. But if you have > > CONFIG_PROVE_RCU_LIST, as noted below, it needs to depend on RCU_EXPERT. > > Ok, will make it depend. But yes for temporary purpose, I will leave it as a > config and remove it later. Very good, thank you! Plus you got another ack. ;-) Thanx, Paul