From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932067Ab3BFSry (ORCPT ); Wed, 6 Feb 2013 13:47:54 -0500 Received: from mail-da0-f43.google.com ([209.85.210.43]:65147 "EHLO mail-da0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757638Ab3BFSrx (ORCPT ); Wed, 6 Feb 2013 13:47:53 -0500 Date: Wed, 6 Feb 2013 10:47:49 -0800 From: Tejun Heo To: Hillf Danton Cc: Rusty Russell , Andrew Morton , Ingo Molnar , LKML Subject: Re: [PATCH 2/3] stop_machine: dequeue work before signal completion Message-ID: <20130206184749.GB2875@htj.dyndns.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 06, 2013 at 08:38:43PM +0800, Hillf Danton wrote: > As handled by the kernel thread, work is dequeued first for further actions. Ditto as the previous patch. > Signed-off-by: Hillf Danton > --- > > --- a/kernel/stop_machine.c Wed Feb 6 19:57:12 2013 > +++ b/kernel/stop_machine.c Wed Feb 6 20:02:12 2013 > @@ -334,23 +334,24 @@ static int __cpuinit cpu_stop_cpu_callba > #ifdef CONFIG_HOTPLUG_CPU > case CPU_UP_CANCELED: > case CPU_POST_DEAD: > - { > - struct cpu_stop_work *work; > - > sched_set_stop_task(cpu, NULL); > /* kill the stopper */ > kthread_stop(stopper->thread); > /* drain remaining works */ > spin_lock_irq(&stopper->lock); > - list_for_each_entry(work, &stopper->works, list) > + while (!list_empty(&stopper->works)) { > + struct cpu_stop_work *work; > + work = list_first_entry(&stopper->works, > + struct cpu_stop_work, list); > + list_del_init(&work->list); > cpu_stop_signal_done(work->done, false, 0); > + } > stopper->enabled = false; > spin_unlock_irq(&stopper->lock); Why does this matter? It's inside spinlock. What's being made better by this change? -- tejun