[PATCH] cgroup: Check task_lock in task_subsys_state()
Paul E. McKenney
paulmck at linux.vnet.ibm.com
Thu Apr 22 21:10:03 PDT 2010
On Fri, Apr 23, 2010 at 10:35:52AM +0800, Li Zefan wrote:
> 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 <lizf at cn.fujitsu.com>
> I'm not sure which is preferable - access ->alloc_lock directly
> like this patch or add task_lock_is_held() in sched.h
This is for the maintainers to decide, either way works from my viewpoint.
I have queued it as is with Matt's Acked-by, and am testing it. Thank you!!!
> 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) ||
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