From patchwork Mon Nov 9 12:55:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 322752 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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 737FFC2D0A3 for ; Mon, 9 Nov 2020 13:14:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 22A3720789 for ; Mon, 9 Nov 2020 13:14:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604927660; bh=HXXDDhHT/PVr0uTyiRq5LQs+DtkArTc9wUC0veTiIwg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=xGy1BxuYVIndbKSjnLXbITcLID/Emvs4DOZcdFm1B2S3BT9BI5x+opr59B6jqutMv Jd+cJWP4NGee6qTmK3RiAOQ24entBmyHaAAwCIgXY0m5Zqi8E0opmLx21K1ZU06NCq YYPDPaw0hOgd+glncTJ9wGKr776gn3dSMJuTeffw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733092AbgKINOP (ORCPT ); Mon, 9 Nov 2020 08:14:15 -0500 Received: from mail.kernel.org ([198.145.29.99]:40390 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733081AbgKINOO (ORCPT ); Mon, 9 Nov 2020 08:14:14 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 97B4F2083B; Mon, 9 Nov 2020 13:14:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604927653; bh=HXXDDhHT/PVr0uTyiRq5LQs+DtkArTc9wUC0veTiIwg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PZwQoU7o2lxAOjQ504FxxAvUenHhGryNqlwO0XCkeK1xRPrLHkip5NMXm3XsbfdfN 96uSwIwN46bhbo8pECZHolHP+bJoSG2GGdvHRDbIZpEMhhhYyiESHKaTNu3YqXZOhp jc6X4yHbo8t7KSYpAaNIaBHzRNKyg09c1rsJdMX0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zqiang , Andrew Morton , Petr Mladek , Tejun Heo , Linus Torvalds Subject: [PATCH 5.4 31/85] kthread_worker: prevent queuing delayed work from timer_fn when it is being canceled Date: Mon, 9 Nov 2020 13:55:28 +0100 Message-Id: <20201109125024.083132029@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201109125022.614792961@linuxfoundation.org> References: <20201109125022.614792961@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Zqiang commit 6993d0fdbee0eb38bfac350aa016f65ad11ed3b1 upstream. 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. Signed-off-by: Zqiang Signed-off-by: Andrew Morton Reviewed-by: Petr Mladek Acked-by: Tejun Heo Cc: Link: https://lkml.kernel.org/r/20201014083030.16895-1-qiang.zhang@windriver.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- kernel/kthread.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -873,7 +873,8 @@ void kthread_delayed_work_timer_fn(struc /* 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); }