1 files changed, 14 insertions, 21 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4d872e19244b..2a87bdde8d4e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7536,7 +7536,7 @@ void set_curr_task(int cpu, struct task_struct *p)
 /* task_group_lock serializes the addition/removal of task groups */
 static DEFINE_SPINLOCK(task_group_lock);
 
-static void free_sched_group(struct task_group *tg)
+static void sched_free_group(struct task_group *tg)
 {
         free_fair_sched_group(tg);
         free_rt_sched_group(tg);
@@ -7562,7 +7562,7 @@ struct task_group *sched_create_group(struct task_group *parent)
         return tg;
 
 err:
-        free_sched_group(tg);
+        sched_free_group(tg);
         return ERR_PTR(-ENOMEM);
 }
 
@@ -7582,17 +7582,16 @@ void sched_online_group(struct task_group *tg, struct task_group *parent)
 }
 
 /* rcu callback to free various structures associated with a task group */
-static void free_sched_group_rcu(struct rcu_head *rhp)
+static void sched_free_group_rcu(struct rcu_head *rhp)
 {
         /* now it should be safe to free those cfs_rqs */
-        free_sched_group(container_of(rhp, struct task_group, rcu));
+        sched_free_group(container_of(rhp, struct task_group, rcu));
 }
 
-/* Destroy runqueue etc associated with a task group */
 void sched_destroy_group(struct task_group *tg)
 {
         /* wait for possible concurrent references to cfs_rqs complete */
-        call_rcu(&tg->rcu, free_sched_group_rcu);
+        call_rcu(&tg->rcu, sched_free_group_rcu);
 }
 
 void sched_offline_group(struct task_group *tg)
@@ -8051,31 +8050,26 @@ cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
         if (IS_ERR(tg))
                 return ERR_PTR(-ENOMEM);
 
+        sched_online_group(tg, parent);
+
         return &tg->css;
 }
 
-static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
+static void cpu_cgroup_css_released(struct cgroup_subsys_state *css)
 {
         struct task_group *tg = css_tg(css);
-        struct task_group *parent = css_tg(css->parent);
 
-        if (parent)
-                sched_online_group(tg, parent);
-        return 0;
+        sched_offline_group(tg);
 }
 
 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
 {
         struct task_group *tg = css_tg(css);
 
-        sched_destroy_group(tg);
-}
-
-static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
-{
-        struct task_group *tg = css_tg(css);
-
-        sched_offline_group(tg);
+        /*
+         * Relies on the RCU grace period between css_released() and this.
+         */
+        sched_free_group(tg);
 }
 
 static void cpu_cgroup_fork(struct task_struct *task)
@@ -8435,9 +8429,8 @@ static struct cftype cpu_files[] = {
 
 struct cgroup_subsys cpu_cgrp_subsys = {
         .css_alloc      = cpu_cgroup_css_alloc,
+        .css_released   = cpu_cgroup_css_released,
         .css_free       = cpu_cgroup_css_free,
-        .css_online     = cpu_cgroup_css_online,
-        .css_offline    = cpu_cgroup_css_offline,
         .fork           = cpu_cgroup_fork,
         .can_attach     = cpu_cgroup_can_attach,
         .attach         = cpu_cgroup_attach,