From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756802AbZA3Vt3 (ORCPT ); Fri, 30 Jan 2009 16:49:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753753AbZA3VtS (ORCPT ); Fri, 30 Jan 2009 16:49:18 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:37354 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753006AbZA3VtS (ORCPT ); Fri, 30 Jan 2009 16:49:18 -0500 Date: Fri, 30 Jan 2009 13:47:36 -0800 From: Andrew Morton To: Oleg Nesterov Cc: hch@lst.de, ebiederm@xmission.com, mingo@elte.hu, xemul@openvz.org, rusty@rustcorp.com.au, vgusev@openvz.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4] kthreads: rework kthread_stop() Message-Id: <20090130134736.ce5910aa.akpm@linux-foundation.org> In-Reply-To: <20090130123358.GA26216@redhat.com> References: <20090130123358.GA26216@redhat.com> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 30 Jan 2009 13:33:58 +0100 Oleg Nesterov wrote: > int kthread_stop(struct task_struct *k) > { > + struct kthread *kthread; > int ret; > > - mutex_lock(&kthread_stop_lock); > - > - /* It could exit after stop_info.k set, but before wake_up_process. */ > - get_task_struct(k); > - > trace_sched_kthread_stop(k); > + get_task_struct(k); > > - /* Must init completion *before* thread sees kthread_stop_info.k */ > - init_completion(&kthread_stop_info.done); > - smp_wmb(); > + kthread = to_kthread(k); > + barrier(); /* it might have exited */ Why the change from smp_wmb() to plain old barrier()?