cgroup: separate out cgroup_has_live_children() from cgroup_destroy_locked()

We're expecting another user.

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

1 files changed, 16 insertions, 10 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b57a949ae4bc..3f5f48130b6b 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3295,6 +3295,21 @@ css_next_descendant_post(struct cgroup_subsys_state *pos,
         return css_parent(pos);
 }
 
+static bool cgroup_has_live_children(struct cgroup *cgrp)
+{
+        struct cgroup *child;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(child, &cgrp->children, sibling) {
+                if (!cgroup_is_dead(child)) {
+                        rcu_read_unlock();
+                        return true;
+                }
+        }
+        rcu_read_unlock();
+        return false;
+}
+
 /**
  * css_advance_task_iter - advance a task itererator to the next css_set
  * @it: the iterator to advance
@@ -4465,7 +4480,6 @@ static void kill_css(struct cgroup_subsys_state *css)
 static int cgroup_destroy_locked(struct cgroup *cgrp)
         __releases(&cgroup_mutex) __acquires(&cgroup_mutex)
 {
-        struct cgroup *child;
         struct cgroup_subsys_state *css;
         bool empty;
         int ssid;
@@ -4487,15 +4501,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
          * emptiness as dead children linger on it while being destroyed;
          * otherwise, "rmdir parent/child parent" may fail with -EBUSY.
          */
-        empty = true;
-        rcu_read_lock();
-        list_for_each_entry_rcu(child, &cgrp->children, sibling) {
-                empty = cgroup_is_dead(child);
-                if (!empty)
-                        break;
-        }
-        rcu_read_unlock();
-        if (!empty)
+        if (cgroup_has_live_children(cgrp))
                 return -EBUSY;
 
         /*