cgroup: replace cgroup_on_dfl() tests in controllers with cgroup_subsys_on_dfl()
cgroup_on_dfl() tests whether the cgroup's root is the default
hierarchy; however, an individual controller is only interested in
whether the controller is attached to the default hierarchy and never
tests a cgroup which doesn't belong to the hierarchy that the
controller is attached to.
This patch replaces cgroup_on_dfl() tests in controllers with faster
static_key based cgroup_subsys_on_dfl(). This leaves cgroup core as
the only user of cgroup_on_dfl() and the function is moved from the
header file to cgroup.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6ddaeba..b35c4cc 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -434,7 +434,7 @@
memcg = page->mem_cgroup;
- if (!memcg || !cgroup_on_dfl(memcg->css.cgroup))
+ if (!memcg || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
memcg = root_mem_cgroup;
rcu_read_unlock();
@@ -5059,7 +5059,7 @@
* guarantees that @root doesn't have any children, so turning it
* on for the root memcg is enough.
*/
- if (cgroup_on_dfl(root_css->cgroup))
+ if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
root_mem_cgroup->use_hierarchy = true;
else
root_mem_cgroup->use_hierarchy = false;