Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754132AbYGVJNL (ORCPT ); Tue, 22 Jul 2008 05:13:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751414AbYGVJM6 (ORCPT ); Tue, 22 Jul 2008 05:12:58 -0400 Received: from x346.tv-sign.ru ([89.108.83.215]:58094 "EHLO mail.screens.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751306AbYGVJM5 (ORCPT ); Tue, 22 Jul 2008 05:12:57 -0400 Date: Tue, 22 Jul 2008 13:16:36 +0400 From: Oleg Nesterov To: Akinobu Mita Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: + workqueue-proper-error-unwinding-in-cpu-hotplug-error-path.patch added to -mm tree Message-ID: <20080722091636.GA241@tv-sign.ru> References: <200807220826.m6M8Q4I6018588@imap1.linux-foundation.org> <20080722084526.GA165@tv-sign.ru> <20080722085938.GA5857@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080722085938.GA5857@localhost.localdomain> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2764 Lines: 90 On 07/22, Akinobu Mita wrote: > > On Tue, Jul 22, 2008 at 12:45:26PM +0400, Oleg Nesterov wrote: > > > > > > From: Akinobu Mita > > > > > > --- a/kernel/workqueue.c~workqueue-proper-error-unwinding-in-cpu-hotplug-error-path > > > +++ a/kernel/workqueue.c > > > @@ -928,6 +928,15 @@ static int __devinit workqueue_cpu_callb > > > break; > > > printk(KERN_ERR "workqueue [%s] for %i failed\n", > > > wq->name, cpu); > > > + > > > + list_for_each_entry_continue_reverse(wq, &workqueues, > > > + list) { > > > + cwq = per_cpu_ptr(wq->cpu_wq, cpu); > > > + start_workqueue_thread(cwq, -1); > > > + cleanup_workqueue_thread(cwq); > > > + } > > > + cpu_clear(cpu, cpu_populated_map); > > > + > > > return NOTIFY_BAD; > > > > If CPU_UP_PREPARE fails, _cpu_up() sends CPU_UP_CANCELED, and afaics > > workqueue_cpu_callback() correctly cleanups cwq->thread's. > > _cpu_up() does not send CPU_UP_CANCELED to the callback which has > returned NOTIFY_BAD. > > The behavior was changed by this commit: > > commit a0d8cdb652d35af9319a9e0fb7134de2a276c636 > Author: Akinobu Mita > Date: Thu Oct 18 03:05:12 2007 -0700 > > cpu hotplug: cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks with CPU_UP_PREPARE Thanks Akinobu! Can't we simplify the fix? I don't like the fact that the CPU_UP_CANCELED logic is duplicated. What do you think about the patch below? Oleg. --- 26-rc2/kernel/workqueue.c~WQ_CPU_UP_PREPARE 2008-07-12 19:40:57.000000000 +0400 +++ 26-rc2/kernel/workqueue.c 2008-07-22 13:15:16.000000000 +0400 @@ -911,6 +911,7 @@ static int __devinit workqueue_cpu_callb unsigned int cpu = (unsigned long)hcpu; struct cpu_workqueue_struct *cwq; struct workqueue_struct *wq; + int ret = NOTIFY_OK; action &= ~CPU_TASKS_FROZEN; @@ -919,6 +920,7 @@ static int __devinit workqueue_cpu_callb cpu_set(cpu, cpu_populated_map); } +cancel: list_for_each_entry(wq, &workqueues, list) { cwq = per_cpu_ptr(wq->cpu_wq, cpu); @@ -928,7 +930,9 @@ static int __devinit workqueue_cpu_callb break; printk(KERN_ERR "workqueue [%s] for %i failed\n", wq->name, cpu); - return NOTIFY_BAD; + action = CPU_UP_CANCELED; + ret = NOTIFY_BAD; + goto cancel; case CPU_ONLINE: start_workqueue_thread(cwq, cpu); @@ -948,7 +952,7 @@ static int __devinit workqueue_cpu_callb cpu_clear(cpu, cpu_populated_map); } - return NOTIFY_OK; + return ret; } void __init init_workqueues(void) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/