[PATCH] memcg: cleanup root memcg checks

[Shakeel Butt]

Replace the implicit checking of root memcg with explicit root memcg
checking i.e. !css->parent with mem_cgroup_is_root().

Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
---
 mm/memcontrol.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index dcb5665aeb69..79046ad3eec0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4141,7 +4141,7 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
 	if (val > 100)
 		return -EINVAL;
 
-	if (css->parent)
+	if (!mem_cgroup_is_root(memcg))
 		memcg->swappiness = val;
 	else
 		vm_swappiness = val;
@@ -4491,7 +4491,7 @@ static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 
 	/* cannot set to root cgroup and only 0 and 1 are allowed */
-	if (!css->parent || !((val == 0) || (val == 1)))
+	if (mem_cgroup_is_root(memcg) || !((val == 0) || (val == 1)))
 		return -EINVAL;
 
 	memcg->oom_kill_disable = val;
-- 
2.30.0.617.g56c4b15f3c-goog