From: Tejun Heo <tj@kernel.org>
Date: Sat, 8 Feb 2014 15:36:58 +0000 (-0500)
Subject: cgroup: update locking in cgroup_show_options()
X-Git-Tag: v3.15-rc1~109^2~73
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=69e943b7d3c2dcca1087e03e556ac6cb0d4433b4;p=pandora-kernel.git

cgroup: update locking in cgroup_show_options()

cgroup_show_options() grabs cgroup_root_mutex to protect the options
changing while printing; however, holding root_mutex or not doesn't
really make much difference for the function.  subsys_mask can be
atomically tested and most of the options aren't allowed to change
anyway once mounted.

The only field which needs synchronization is ->release_agent_path.
This patch introduces a dedicated spinlock to synchronize accesses to
the field and drops cgroup_root_mutex locking from
cgroup_show_options().  The next patch will remove cgroup_root_mutex.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
---

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