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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 614BAC10F14 for ; Tue, 15 Oct 2019 12:57:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 425CF217F9 for ; Tue, 15 Oct 2019 12:57:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729167AbfJOM5z (ORCPT ); Tue, 15 Oct 2019 08:57:55 -0400 Received: from foss.arm.com ([217.140.110.172]:38306 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725871AbfJOM5y (ORCPT ); Tue, 15 Oct 2019 08:57:54 -0400 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 234401000; Tue, 15 Oct 2019 05:57:54 -0700 (PDT) Received: from [10.1.194.37] (e113632-lin.cambridge.arm.com [10.1.194.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1C0643F718; Tue, 15 Oct 2019 05:57:53 -0700 (PDT) Subject: Re: [PATCH v2] sched/topology: Allow sched_asym_cpucapacity to be disabled To: Quentin Perret Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, peterz@infradead.org, vincent.guittot@linaro.org, Dietmar.Eggemann@arm.com, morten.rasmussen@arm.com, stable@vger.kernel.org References: <20191015102956.20133-1-valentin.schneider@arm.com> <20191015104010.GA242992@google.com> <20191015115632.GC242992@google.com> From: Valentin Schneider Message-ID: Date: Tue, 15 Oct 2019 13:57:51 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191015115632.GC242992@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15/10/2019 12:56, Quentin Perret wrote: > Hmm, a problem here is that static_branch*() can block (it uses a > mutex) while you're in the rcu section, I think. > > I suppose you could just move this above rcu_read_lock() and use > rcu_access_pointer() instead ? > Right, I got confused again, the only problem is with the rcu_read_lock(), so the increment is fine but the decrement isn't. Let me try this again with more coffee. > Thanks, > Quentin >