From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753603Ab1HaKVS (ORCPT ); Wed, 31 Aug 2011 06:21:18 -0400 Received: from mail-ey0-f174.google.com ([209.85.215.174]:35072 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752264Ab1HaKVQ (ORCPT ); Wed, 31 Aug 2011 06:21:16 -0400 Date: Wed, 31 Aug 2011 12:21:07 +0200 From: Tejun Heo To: "Rafael J. Wysocki" , Oleg Nesterov , Paul Menage Cc: containers@lists.linux-foundation.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [PATCH pm-freezer 1/4] cgroup_freezer: fix freezer->state setting bug in freezer_change_state() Message-ID: <20110831102100.GA2828@mtj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org d02f52811d0e "cgroup_freezer: prepare for removal of TIF_FREEZE" moved setting of freezer->state into freezer_change_state(); unfortunately, while doing so, when it's beginning to freeze tasks, it sets the state to CGROUP_FROZEN instead of CGROUP_FREEZING ending up skipping the whole freezing state. Fix it. -v2: Oleg pointed out that re-freezing FROZEN cgroup could increment system_freezing_cnt. Fixed. Signed-off-by: Tejun Heo Reported-by: Oleg Nesterov Cc: Paul Menage Cc: "Rafael J. Wysocki" --- I'm in the process of moving and can only use a quite old laptop. I tested compile but couldn't really do much else, so please proceed with caution. Oleg, can you please ack the patches if you agree with the updated versions? Thanks. kernel/cgroup_freezer.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) Index: work/kernel/cgroup_freezer.c =================================================================== --- work.orig/kernel/cgroup_freezer.c +++ work/kernel/cgroup_freezer.c @@ -308,24 +308,26 @@ static int freezer_change_state(struct c 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); - unfreeze_cgroup(cgroup, freezer); + if (freezer->state != CGROUP_THAWED) { + freezer->state = CGROUP_THAWED; + atomic_dec(&system_freezing_cnt); + unfreeze_cgroup(cgroup, freezer); + } break; case CGROUP_FROZEN: - atomic_inc(&system_freezing_cnt); - retval = try_to_freeze_cgroup(cgroup, freezer); + if (freezer->state == CGROUP_THAWED) { + freezer->state = CGROUP_FREEZING; + atomic_inc(&system_freezing_cnt); + retval = try_to_freeze_cgroup(cgroup, freezer); + } break; default: BUG(); } -out: + spin_unlock_irq(&freezer->lock); return retval;