Commit f5f60d23 authored by Wei Yang's avatar Wei Yang Committed by Tejun Heo
Browse files

cgroup/rstat: check updated_next only for root 



After commit dc26532a ("cgroup: rstat: punt root-level optimization to
individual controllers"), each rstat on updated_children list has its
->updated_next not NULL.

This means we can remove the check on ->updated_next, if we make sure
the subtree from @root is on list, which could be done by checking
updated_next for root.

tj: Coding style fixes.

Signed-off-by: default avatarWei Yang <richard.weiyang@gmail.com>
Reviewed-by: default avatarMichal Koutný <mkoutny@suse.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 0da41f73

kernel/cgroup/rstat.c

+23 −24
Original line number Diff line number Diff line
@@ -88,6 +88,7 @@ static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos, 
						   struct cgroup *root, int cpu)

{

	struct cgroup_rstat_cpu *rstatc;

	struct cgroup *parent;



	if (pos == root)

		return NULL;
@@ -96,10 +97,14 @@ static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos, 
	 * We're gonna walk down to the first leaf and visit/remove it.  We

	 * can pick whatever unvisited node as the starting point.

	 */

	if (!pos)

	if (!pos) {

		pos = root;

	else

		/* return NULL if this subtree is not on-list */

		if (!cgroup_rstat_cpu(pos, cpu)->updated_next)

			return NULL;

	} else {

		pos = cgroup_parent(pos);

	}



	/* walk down to the first leaf */

	while (true) {
@@ -115,9 +120,7 @@ static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos, 
	 * However, due to the way we traverse, @pos will be the first

	 * child in most cases. The only exception is @root.

	 */

	if (rstatc->updated_next) {

		struct cgroup *parent = cgroup_parent(pos);



	parent = cgroup_parent(pos);

	if (parent) {

		struct cgroup_rstat_cpu *prstatc;

		struct cgroup **nextp;
@@ -138,10 +141,6 @@ static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos, 
	return pos;

}



	/* only happens for @root */

	return NULL;

}



/* see cgroup_rstat_flush() */

static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)

	__releases(&cgroup_rstat_lock) __acquires(&cgroup_rstat_lock)