commit 99bae5f94185c2cc65701e95c54e31e2f4345b88
author Li Zefan <lizefan@huawei.com> Thu Jun 12 14:31:31 2014 +0800
committer Tejun Heo <tj@kernel.org> Tue Jun 17 18:52:53 2014 -0400
tree 9cb7db676c228bd7e3ea9fbd221a6303ca2628ee
parent ebe06187bf2aec10d537ce4595e416035367d703

cgroup: fix broken css_has_online_children()

After running:

  # mount -t cgroup cpu xxx /cgroup && mkdir /cgroup/sub && \
    rmdir /cgroup/sub && umount /cgroup

I found the cgroup root still existed:

  # cat /proc/cgroups
  #subsys_name    hierarchy       num_cgroups     enabled
  cpuset  0       1       1
  cpu     1       1       1
  ...

It turned out css_has_online_children() is broken.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Sigend-off-by: Tejun Heo <tj@kernel.org>

kernel/cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 7868fc3..d9a8be9 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3328,7 +3328,7 @@
 
 	rcu_read_lock();
 	css_for_each_child(child, css) {
-		if (css->flags & CSS_ONLINE) {
+		if (child->flags & CSS_ONLINE) {
 			ret = true;
 			break;
 		}