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=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 47A5CC433E7 for ; Mon, 31 Aug 2020 20:29:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 26E9F20866 for ; Mon, 31 Aug 2020 20:29:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728464AbgHaU3g (ORCPT ); Mon, 31 Aug 2020 16:29:36 -0400 Received: from mx2.suse.de ([195.135.220.15]:38736 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726167AbgHaU3e (ORCPT ); Mon, 31 Aug 2020 16:29:34 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 84576AD39; Mon, 31 Aug 2020 20:29:32 +0000 (UTC) From: Davidlohr Bueso To: tsbogend@alpha.franken.de Cc: oleg@redhat.com, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, dave@stgolabs.net, Davidlohr Bueso Subject: [PATCH] MIPS: Use rcu to lookup a task in mipsmt_sys_sched_setaffinity() Date: Mon, 31 Aug 2020 13:14:02 -0700 Message-Id: <20200831201402.2837-1-dave@stgolabs.net> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The call simply looks up the corresponding task (without iterating the tasklist), which is safe under rcu instead of the tasklist_lock. In addition, the setaffinity counter part already does this. Signed-off-by: Davidlohr Bueso --- arch/mips/kernel/mips-mt-fpaff.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/mips/kernel/mips-mt-fpaff.c b/arch/mips/kernel/mips-mt-fpaff.c index 1a08428eedcf..6c590ef27648 100644 --- a/arch/mips/kernel/mips-mt-fpaff.c +++ b/arch/mips/kernel/mips-mt-fpaff.c @@ -167,7 +167,7 @@ asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len, return -EINVAL; get_online_cpus(); - read_lock(&tasklist_lock); + rcu_read_lock(); retval = -ESRCH; p = find_process_by_pid(pid); @@ -181,7 +181,7 @@ asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len, cpumask_and(&mask, &allowed, cpu_active_mask); out_unlock: - read_unlock(&tasklist_lock); + rcu_read_unlock(); put_online_cpus(); if (retval) return retval; -- 2.26.2