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, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 7356AC432C0 for ; Wed, 27 Nov 2019 12:10:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45B3A2071E for ; Wed, 27 Nov 2019 12:10:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726694AbfK0MK3 (ORCPT ); Wed, 27 Nov 2019 07:10:29 -0500 Received: from foss.arm.com ([217.140.110.172]:46938 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726540AbfK0MK3 (ORCPT ); Wed, 27 Nov 2019 07:10:29 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C48DF30E; Wed, 27 Nov 2019 04:10:28 -0800 (PST) Received: from bogus (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 54C553F6C4; Wed, 27 Nov 2019 04:10:27 -0800 (PST) Date: Wed, 27 Nov 2019 12:10:25 +0000 From: Sudeep Holla To: Viresh Kumar Cc: Dietmar Eggemann , "Rafael J . Wysocki" , Liviu Dudau , Lorenzo Pieralisi , Morten Rasmussen , Sudeep Holla , Lukasz Luba , linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] cpufreq: vexpress-spc: Fix wrong alternation of policy->related_cpus during CPU hp Message-ID: <20191127121025.GD29301@bogus> References: <20191127114801.23837-1-dietmar.eggemann@arm.com> <20191127120744.iivgw25nixovfj7i@vireshk-i7> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191127120744.iivgw25nixovfj7i@vireshk-i7> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Wed, Nov 27, 2019 at 05:37:44PM +0530, Viresh Kumar wrote: > On 27-11-19, 12:48, Dietmar Eggemann wrote: > > Since commit ca74b316df96 ("arm: Use common cpu_topology structure and > > functions.") the core cpumask has to be modified during cpu hotplug > > operations. > > > > ("arm: Fix topology setup in case of CPU hotplug for CONFIG_SCHED_MC") > > [1] fixed that but revealed another issue on TC2, i.e in its cpufreq > > driver. > > > > During CPU hp stress operations on multiple CPUs, policy->related_cpus > > can be altered. This is wrong since this cpumask should contain the > > online and offline CPUs. > > > > The WARN_ON(!cpumask_test_cpu(cpu, policy->related_cpus)) in > > cpufreq_online() triggers in this case. > > > > The core cpumask can't be used to set the policy->cpus in > > ve_spc_cpufreq_init() anymore in case it is called via > > cpuhp_cpufreq_online()->cpufreq_online()->cpufreq_driver->init(). > > > > An empty online() callback can be used to avoid that the init() > > driver function is called during CPU hotplug in so that > > policy->related_cpus will not be changed. > > > > Implementing an online() also requires an offline() callback. > > > > Tested on TC2 with CPU hp stress test (CPU hp from multiple CPUs at > > the same time). > > > > [1] > > https://lore.kernel.org/r/20191127103353.12417-1-dietmar.eggemann@arm.com > > > > Signed-off-by: Dietmar Eggemann > > Wanna provide any fixes tag ? > > > --- > > drivers/cpufreq/vexpress-spc-cpufreq.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > This is 5.5 material or 5.6 ? > v5.5 for sure, broken even on v5.4 but unless someone really cares for stable on TC2, I am happy to skip it. -- Regards, Sudeep