cgroup: make cgroup_css() take cgroup_subsys * instead and allow NULL subsys
cgroup_css() is no longer used in hot paths. Make it take struct
cgroup_subsys * and allow the users to specify NULL subsys to obtain
the dummy_css. This removes open-coded NULL subsystem testing in a
couple users and generally simplifies the code.
After this patch, css_from_dir() also allows NULL @ss and returns the
matching dummy_css. This behavior change doesn't affect its only user
- perf.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
1 file changed