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=-11.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 25474C3F2D1 for ; Wed, 4 Mar 2020 08:57:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F108721741 for ; Wed, 4 Mar 2020 08:57:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387771AbgCDI52 (ORCPT ); Wed, 4 Mar 2020 03:57:28 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:46286 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727734AbgCDI51 (ORCPT ); Wed, 4 Mar 2020 03:57:27 -0500 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1j9PqH-0007Aw-5o; Wed, 04 Mar 2020 09:57:25 +0100 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 57EE11C20C4; Wed, 4 Mar 2020 09:57:24 +0100 (CET) Date: Wed, 04 Mar 2020 08:57:23 -0000 From: "tip-bot2 for Eric W. Biederman" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: timers/core] posix-cpu-timers: Stop disabling timers on mt-exec Cc: "Eric W. Biederman" , Thomas Gleixner , x86 , LKML In-Reply-To: <87o8tityzs.fsf@x220.int.ebiederm.org> References: <87o8tityzs.fsf@x220.int.ebiederm.org> MIME-Version: 1.0 Message-ID: <158331224395.28353.17725920486129300292.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the timers/core branch of tip: Commit-ID: b95e31c07c5eb4f5c0769f12b38b0343d7961040 Gitweb: https://git.kernel.org/tip/b95e31c07c5eb4f5c0769f12b38b0343d7961040 Author: Eric W. Biederman AuthorDate: Fri, 28 Feb 2020 11:15:03 -06:00 Committer: Thomas Gleixner CommitterDate: Wed, 04 Mar 2020 09:54:55 +01:00 posix-cpu-timers: Stop disabling timers on mt-exec The reasons why the extra posix_cpu_timers_exit_group() invocation has been added are not entirely clear from the commit message. Today all that posix_cpu_timers_exit_group() does is stop timers that are tracking the task from firing. Every other operation on those timers is still allowed. The practical implication of this is posix_cpu_timer_del() which could not get the siglock after the thread group leader has exited (because sighand == NULL) would be able to run successfully because the timer was already dequeued. With that locking issue fixed there is no point in disabling all of the timers. So remove this ``tempoary'' hack. Fixes: e0a70217107e ("posix-cpu-timers: workaround to suppress the problems with mt exec") Signed-off-by: "Eric W. Biederman" Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/87o8tityzs.fsf@x220.int.ebiederm.org --- kernel/exit.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 2833ffb..df54631 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -103,17 +103,8 @@ static void __exit_signal(struct task_struct *tsk) #ifdef CONFIG_POSIX_TIMERS posix_cpu_timers_exit(tsk); - if (group_dead) { + if (group_dead) posix_cpu_timers_exit_group(tsk); - } else { - /* - * This can only happen if the caller is de_thread(). - * FIXME: this is the temporary hack, we should teach - * posix-cpu-timers to handle this case correctly. - */ - if (unlikely(has_group_leader_pid(tsk))) - posix_cpu_timers_exit_group(tsk); - } #endif if (group_dead) {