From: Tejun Heo <tj@kernel.org>
Date: Fri, 21 Jun 2013 22:52:04 +0000 (-0700)
Subject: cgroup: fix RCU accesses around task->cgroups
X-Git-Tag: omap-for-v3.11/fixes-for-merge-window~44^2~4
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a8ad805cfde00be8fe3b3dae8890996dbeb91e2c;p=pandora-kernel.git

cgroup: fix RCU accesses around task->cgroups

There are several places in kernel/cgroup.c where task->cgroups is
accessed and modified without going through proper RCU accessors.
None is broken as they're all lock protected accesses; however, this
still triggers sparse RCU address space warnings.

* Consistently use task_css_set() for task->cgroups dereferencing.

* Use RCU_INIT_POINTER() to clear task->cgroups to &init_css_set on
  exit.

* Remove unnecessary rcu_dereference_raw() from cset->subsys[]
  dereference in cgroup_exit().

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Li Zefan <lizefan@huawei.com>
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