tree 24cbd5b2d01808ab870f95061c8af419b3d687ee
parent c29adf24e0c443fb4433efb6a62bd91fdb739c34
author Tejun Heo <tj@kernel.org> 1404856976 -0400
committer Tejun Heo <tj@kernel.org> 1404856976 -0400

cgroup: introduce cgroup->subtree_control

cgroup is implementing support for subsystem dependency which would
require a way to enable a subsystem even when it's not directly
configured through "cgroup.subtree_control".

Previously, cgroup->child_subsys_mask directly reflected
"cgroup.subtree_control" and the enabled subsystems in the child
cgroups.  This patch adds cgroup->subtree_control which
"cgroup.subtree_control" operates on.  cgroup->child_subsys_mask is
now calculated from cgroup->subtree_control by
cgroup_refresh_child_subsys_mask(), which sets it identical to
cgroup->subtree_control for now.

This will allow using cgroup->child_subsys_mask for all the enabled
subsystems including the implicit ones and ->subtree_control for
tracking the explicitly requested ones.  This patch keeps the two
masks identical and doesn't introduce any behavior changes.

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