cgroup: allow ->post_create() to fail

There could be cases where controllers want to do initialization
operations which may fail from ->post_create().  This patch makes
->post_create() return -errno to indicate failure and online_css()
relay such failures.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Glauber Costa <glommer@parallels.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 670a4af7dc94..ee8bb671688c 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -112,7 +112,7 @@ static struct cgroup_subsys_state *freezer_create(struct cgroup *cgroup)
  * parent's freezing state while holding both parent's and our
  * freezer->lock.
  */
-static void freezer_post_create(struct cgroup *cgroup)
+static int freezer_post_create(struct cgroup *cgroup)
 {
         struct freezer *freezer = cgroup_freezer(cgroup);
         struct freezer *parent = parent_freezer(freezer);
@@ -136,6 +136,8 @@ static void freezer_post_create(struct cgroup *cgroup)
         spin_unlock(&freezer->lock);
         if (parent)
                 spin_unlock_irq(&parent->lock);
+
+        return 0;
 }
 
 /**