From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755387AbbIHRRn (ORCPT ); Tue, 8 Sep 2015 13:17:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33768 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755226AbbIHRRj (ORCPT ); Tue, 8 Sep 2015 13:17:39 -0400 Date: Tue, 8 Sep 2015 19:14:52 +0200 From: Oleg Nesterov To: Al Viro , Eric Dumazet , Linus Torvalds Cc: Andrew Morton , Ingo Molnar , Maciej =?utf-8?Q?=C5=BBenczykowski?= , Peter Zijlstra , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: [PATCH 3/3] Revert "task_work: remove fifo ordering guarantee" Message-ID: <20150908171452.GA14599@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150908171433.GA14573@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This reverts commit c82199061009d1561e31e17fca5e47a87cb7ff4c. Now that fput() can't abuse ->task_works list, we can restore the FIFO ordering. Yes, currently there are no in-kernel users which need this, but I think task_work_add() will have more users and FIFO makes more sense if (unlike fput/mntput) the callbacks change the task's state. Signed-off-by: Oleg Nesterov --- kernel/task_work.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/task_work.c b/kernel/task_work.c index 53fa971..8727032 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -18,8 +18,6 @@ static struct callback_head work_exited; /* all we need is ->next == NULL */ * This is like the signal handler which runs in kernel mode, but it doesn't * try to wake up the @task. * - * Note: there is no ordering guarantee on works queued here. - * * RETURNS: * 0 if succeeds or -ESRCH. */ @@ -110,6 +108,16 @@ void task_work_run(void) raw_spin_unlock_wait(&task->pi_lock); smp_mb(); + /* Reverse the list to run the works in fifo order */ + head = NULL; + do { + next = work->next; + work->next = head; + head = work; + work = next; + } while (work); + + work = head; do { next = work->next; work->func(work); -- 2.4.3