tree ce449c9df24730dba5f27cb9b3de46d24ba6feb5
parent ce3f1d9d19371045981a64815227bab822554878
author Tejun Heo <tj@kernel.org> 1457017079 -0500
committer Tejun Heo <tj@kernel.org> 1457017079 -0500

cgroup: introduce cgroup_{save|propagate|restore}_control()

While controllers are being enabled and disabled in
cgroup_subtree_control_write(), the original subsystem masks are
stashed in local variables so that they can be restored if the
operation fails in the middle.

This patch adds dedicated fields to struct cgroup to be used instead
of the local variables and implements functions to stash the current
values, propagate the changes and restore them recursively.  Combined
with the previous changes, this makes subsystem management operations
fully recursive and modularlized.  This will be used to expand cgroup
core functionalities.

While at it, remove now unused @css_enable and @css_disable from
cgroup_subtree_control_write().

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