From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zefan Subject: [PATCH] cgroup: Check task_lock in task_subsys_state() Date: Fri, 23 Apr 2010 10:35:52 +0800 Message-ID: <4BD10788.8060006@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Sender: linux-kernel-owner@vger.kernel.org To: "Paul E. McKenney" Cc: Peter Zijlstra , Lai JIangshan , Paul Menage , Matt Helsley , Cedric Le Goater , LKML , "containers@lists.osdl.org" , Andrew Morton List-Id: containers.vger.kernel.org task_subsys_state() is safe under task_lock(). See Documentation/cgroups/cgroups.txt for locking rule. This fixes an RCU warning when resume from suspend. The warning comes from freezer cgroup in cgroup_freezing_or_frozen(). Signed-off-by: Li Zefan --- I'm not sure which is preferable - access ->alloc_lock directly like this patch or add task_lock_is_held() in sched.h --- include/linux/cgroup.h | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index b8ad1ea..8f78073 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -530,6 +530,7 @@ static inline struct cgroup_subsys_state *task_subsys_state( { return rcu_dereference_check(task->cgroups->subsys[subsys_id], rcu_read_lock_held() || + lockdep_is_held(&task->alloc_lock) || cgroup_lock_is_held()); } -- 1.6.3