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=-12.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 EC26EC4346E for ; Sun, 27 Sep 2020 05:57:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A7E58239E5 for ; Sun, 27 Sep 2020 05:57:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730301AbgI0F5C (ORCPT ); Sun, 27 Sep 2020 01:57:02 -0400 Received: from mail5.windriver.com ([192.103.53.11]:57278 "EHLO mail5.wrs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729125AbgI0F5C (ORCPT ); Sun, 27 Sep 2020 01:57:02 -0400 Received: from ALA-HCA.corp.ad.wrs.com (ala-hca.corp.ad.wrs.com [147.11.189.40]) by mail5.wrs.com (8.15.2/8.15.2) with ESMTPS id 08R5sfp4024676 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=FAIL); Sat, 26 Sep 2020 22:55:26 -0700 Received: from pek-qzhang2-d1.wrs.com (128.224.162.183) by ALA-HCA.corp.ad.wrs.com (147.11.189.40) with Microsoft SMTP Server id 14.3.487.0; Sat, 26 Sep 2020 22:54:51 -0700 From: To: , , CC: , Subject: [PATCH v3] kthread_worker: Prevent queuing delayed work from timer_fn when it is being canceled Date: Sun, 27 Sep 2020 13:54:49 +0800 Message-ID: <20200927055449.21389-1-qiang.zhang@windriver.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zqiang There is a small race window when a delayed work is being canceled and the work still might be queued from the timer_fn: CPU0 CPU1 kthread_cancel_delayed_work_sync() __kthread_cancel_work_sync() __kthread_cancel_work() work->canceling++; kthread_delayed_work_timer_fn() kthread_insert_work(); BUG: kthread_insert_work() should not get called when work->canceling is set. Reviewed-by: Petr Mladek Signed-off-by: Zqiang --- v1->v2->v3: Change the description of the problem and add 'Reviewed-by' tags. kernel/kthread.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/kthread.c b/kernel/kthread.c index 3edaa380dc7b..85a2c9b32049 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -897,7 +897,8 @@ void kthread_delayed_work_timer_fn(struct timer_list *t) /* Move the work from worker->delayed_work_list. */ WARN_ON_ONCE(list_empty(&work->node)); list_del_init(&work->node); - kthread_insert_work(worker, work, &worker->work_list); + if (!work->canceling) + kthread_insert_work(worker, work, &worker->work_list); raw_spin_unlock_irqrestore(&worker->lock, flags); } -- 2.17.1