From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752467Ab1IDSGM (ORCPT ); Sun, 4 Sep 2011 14:06:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57401 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752131Ab1IDSGC (ORCPT ); Sun, 4 Sep 2011 14:06:02 -0400 Date: Sun, 4 Sep 2011 20:02:06 +0200 From: Oleg Nesterov To: Tejun Heo Cc: matthltc@us.ibm.com, rjw@sisk.pl, paul@paulmenage.org, containers@lists.linux-foundation.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/6] cgroup_freezer: fix freezer->state setting bug in freezer_change_state() Message-ID: <20110904180206.GA28520@redhat.com> References: <1314988070-12244-1-git-send-email-tj@kernel.org> <1314988070-12244-2-git-send-email-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1314988070-12244-2-git-send-email-tj@kernel.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/03, Tejun Heo wrote: > > @@ -308,24 +308,24 @@ static int freezer_change_state(struct cgroup *cgroup, > spin_lock_irq(&freezer->lock); > > update_if_frozen(cgroup, freezer); > - if (goal_state == freezer->state) > - goto out; > - > - freezer->state = goal_state; > > switch (goal_state) { > case CGROUP_THAWED: > - atomic_dec(&system_freezing_cnt); > + if (freezer->state != CGROUP_THAWED) > + atomic_dec(&system_freezing_cnt); > + freezer->state = CGROUP_THAWED; > unfreeze_cgroup(cgroup, freezer); > break; > case CGROUP_FROZEN: > - atomic_inc(&system_freezing_cnt); > + if (freezer->state == CGROUP_THAWED) > + atomic_inc(&system_freezing_cnt); > + freezer->state = CGROUP_FREEZING; > retval = try_to_freeze_cgroup(cgroup, freezer); Cough. Now it doesn't look right to me ;) If the user write "FROZEN" into the control file, we should not turn the CGROUP_FROZEN state into CGROUP_FREEZING. Probably this is harmless, but this looks wrong and this doesn't match the current behaviour, user-visible change. Oleg.