From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757507Ab2IRIpu (ORCPT ); Tue, 18 Sep 2012 04:45:50 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:64349 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1756746Ab2IRIps (ORCPT ); Tue, 18 Sep 2012 04:45:48 -0400 X-IronPort-AV: E=Sophos;i="4.80,442,1344182400"; d="scan'208";a="5864223" From: Lai Jiangshan To: Tejun Heo , linux-kernel@vger.kernel.org Cc: Lai Jiangshan Subject: [PATCH 2/2] workqueue: Keep activate-order equals to queue_work()-order Date: Tue, 18 Sep 2012 16:36:53 +0800 Message-Id: <1347957414-6692-2-git-send-email-laijs@cn.fujitsu.com> X-Mailer: git-send-email 1.7.4.4 In-Reply-To: <1347957414-6692-1-git-send-email-laijs@cn.fujitsu.com> References: <1347957414-6692-1-git-send-email-laijs@cn.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/09/18 16:35:10, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/09/18 16:35:14, Serialize complete at 2012/09/18 16:35:14 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The whole workqueue.c keeps activate-order equals to queue_work()-order in any given cwq except workqueue_set_max_active(). If this order is not kept, something may be not good: first_work_fn() { release some resource; } second_work_fn() { wait and request the resource; use resource; } 1. user queues the first work. # ->max_active is low, is queued on ->delayed_works. 2. someone increases the >max_active via workqueue_set_max_active() 3. user queues the second work. # queued on cwq->pool. When the second work is launched to execute, it waits the first work to release the resource. But the first work is still in ->delayed_works, it waits the first work to finish and them it can be activated. It is bad. we fix it by activating the first work in the step 2. I can't fully determine that it is workqueue's responsibility or the user's responsibility. If it is workqueue's responsibility, the patch needs go to -stable. If it is user's responsibility. it is a nice cleanup, it can go to for-next. I prefer it is workqueue's responsibility. Signed-off-by: Lai Jiangshan --- kernel/workqueue.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index d0ca063..8783414 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3458,7 +3458,7 @@ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) if (!(wq->flags & WQ_FREEZABLE) || !(gcwq->flags & GCWQ_FREEZING)) - get_cwq(gcwq->cpu, wq)->max_active = max_active; + cwq_set_max_active(get_cwq(gcwq->cpu, wq), max_active); spin_unlock_irq(&gcwq->lock); } -- 1.7.4.4