From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753679Ab1H2QAK (ORCPT ); Mon, 29 Aug 2011 12:00:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56601 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752763Ab1H2QAG (ORCPT ); Mon, 29 Aug 2011 12:00:06 -0400 Date: Mon, 29 Aug 2011 17:56:40 +0200 From: Oleg Nesterov To: Tejun Heo Cc: rjw@sisk.pl, paul@paulmenage.org, linux-kernel@vger.kernel.org, arnd@arndb.de Subject: Re: [PATCH 14/16] freezer: make freezing() test freeze conditions in effect instead of TIF_FREEZE Message-ID: <20110829155640.GA8392@redhat.com> References: <1313763382-12341-1-git-send-email-tj@kernel.org> <1313763382-12341-15-git-send-email-tj@kernel.org> <20110829154944.GA7531@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110829154944.GA7531@redhat.com> 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 I'm afraid I wasn't clear.... On 08/29, Oleg Nesterov wrote: > > On 08/19, Tejun Heo wrote: > > > > @@ -311,9 +315,11 @@ static int freezer_change_state(struct cgroup *cgroup, > > > > switch (goal_state) { > > case CGROUP_THAWED: > > + atomic_dec(&system_freezing_cnt); > > unfreeze_cgroup(cgroup, freezer); > > break; > > case CGROUP_FROZEN: > > + atomic_inc(&system_freezing_cnt); > > This is harmless, but afaics is not exactly right. CGROUP_FROZEN doesn't > need system_freezing_cnt != 0, everything is already frozen and we just > provoke freezing_slow_path() without any reason. Right? Of course, this atomic_inc() is right, we are going to call try_to_freeze_cgroup(). But probably it makes sense to do atomic_dec() when freezer->state becomes CGROUP_FROZEN. Oleg.