From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760716AbYENBcS (ORCPT ); Tue, 13 May 2008 21:32:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752220AbYENBcJ (ORCPT ); Tue, 13 May 2008 21:32:09 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:50797 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751774AbYENBcI (ORCPT ); Tue, 13 May 2008 21:32:08 -0400 Message-ID: <482A40C0.8030708@cn.fujitsu.com> Date: Wed, 14 May 2008 09:30:40 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Paul Menage CC: pj@sgi.com, xemul@openvz.org, balbir@in.ibm.com, serue@us.ibm.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org Subject: Re: [RFC/PATCH 1/8]: CGroup Files: Add locking mode to cgroups control files References: <20080513063707.049448000@menage.corp.google.com> <20080513071522.133586000@menage.corp.google.com> <48295E11.2000003@cn.fujitsu.com> <6599ad830805131407y3d94016cn773ba21a42b6098c@mail.gmail.com> In-Reply-To: <6599ad830805131407y3d94016cn773ba21a42b6098c@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >> > @@ -1518,16 +1580,21 @@ static ssize_t cgroup_file_read(struct f >> > struct cftype *cft = __d_cft(file->f_dentry); >> > struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); >> > >> > - if (!cft || cgroup_is_removed(cgrp)) >> > + if (cgroup_is_removed(cgrp)) >> > return -ENODEV; >> > >> >> This check seems redundant now. >> > > It's not needed for safety, but it doesn't seem to hurt to check > cgroup_is_removed() prior to doing any copying, since we'll fail after > copying anyway if cgroup_is_removed() returns true (once we've taken > any relevant locks). > It's a bit odd to me that cgroup_is_removed() is removed in cgroup_file_write(), but it's ressered here.