cgroup: update locking in cgroup_show_options()
authorTejun Heo <tj@kernel.org>
Sat, 8 Feb 2014 15:36:58 +0000 (10:36 -0500)
committerTejun Heo <tj@kernel.org>
Sat, 8 Feb 2014 15:36:58 +0000 (10:36 -0500)
commit69e943b7d3c2dcca1087e03e556ac6cb0d4433b4
tree79bce2147f3eebb43e4300120a3a0d81b0a97e1c
parentaec25020f5d4b69aea5317551d1cb7043f6b04fb
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>
kernel/cgroup.c