tree 1277b5c533336a1494afdfa8b2eb164d2ca5d9f2
parent ed69d189c4f3615ddbcdabe9443833344e4447a2
author Tejun Heo <tj@kernel.org> 1456198094 -0500
committer Tejun Heo <tj@kernel.org> 1456198094 -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>