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=-10.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, 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 B279CC4338F for ; Thu, 29 Jul 2021 17:31:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95A1860720 for ; Thu, 29 Jul 2021 17:31:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231420AbhG2RbY (ORCPT ); Thu, 29 Jul 2021 13:31:24 -0400 Received: from foss.arm.com ([217.140.110.172]:53702 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229662AbhG2RbX (ORCPT ); Thu, 29 Jul 2021 13:31:23 -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 26F6A1FB; Thu, 29 Jul 2021 10:31:19 -0700 (PDT) Received: from [192.168.178.6] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 739A63F73D; Thu, 29 Jul 2021 10:31:17 -0700 (PDT) Subject: Re: [PATCH v4 2/2] sched: Skip priority checks with SCHED_FLAG_KEEP_PARAMS To: Quentin Perret Cc: mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org, qais.yousef@arm.com, rickyiu@google.com, wvw@google.com, patrick.bellasi@matbug.net, xuewen.yan94@gmail.com, linux-kernel@vger.kernel.org, kernel-team@android.com References: <20210719161656.3833943-1-qperret@google.com> <20210719161656.3833943-3-qperret@google.com> From: Dietmar Eggemann Message-ID: <787ac8b6-3df6-0225-e835-c17a56a8d642@arm.com> Date: Thu, 29 Jul 2021 19:31:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/07/2021 15:56, Quentin Perret wrote: > On Thursday 22 Jul 2021 at 10:47:33 (+0200), Dietmar Eggemann wrote: [...] >>> @@ -7393,6 +7403,8 @@ SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr, >>> rcu_read_unlock(); >>> >>> if (likely(p)) { >>> + if (attr.sched_flags & SCHED_FLAG_KEEP_PARAMS) >>> + get_params(p, &attr); >> >> SCHED_FLAG_KEEP_PARAMS is handled here but SCHED_FLAG_KEEP_POLICY >> outside (before) the `if (likely(p))`? > > Because I need to dereference p while SCHED_FLAG_KEEP_POLICY doesn't :) Ah, true. Looked weird though. But then the SCHED_FLAG_KEEP_POLICY condition can be placed closer to the SCHED_FLAG_KEEP_PARAMS condition. We don't have to set SETPARAM_POLICY if p == NULL. >>> retval = sched_setattr(p, &attr); >>> put_task_struct(p); >>> } [...]