1 files changed, 9 insertions, 4 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index cd81505662b8..a07d55e75698 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -135,7 +135,7 @@ static DEFINE_RWLOCK(qdisc_mod_lock);
 
 static struct Qdisc_ops *qdisc_base;
 
-/* Register/uregister queueing discipline */
+/* Register/unregister queueing discipline */
 
 int register_qdisc(struct Qdisc_ops *qops)
 {
@@ -271,11 +271,16 @@ static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
         return NULL;
 }
 
-static void qdisc_list_add(struct Qdisc *q)
+void qdisc_list_add(struct Qdisc *q)
 {
-        if ((q->parent != TC_H_ROOT) && !(q->flags & TCQ_F_INGRESS))
-                list_add_tail(&q->list, &qdisc_dev(q)->qdisc->list);
+        if ((q->parent != TC_H_ROOT) && !(q->flags & TCQ_F_INGRESS)) {
+                struct Qdisc *root = qdisc_dev(q)->qdisc;
+
+                WARN_ON_ONCE(root == &noop_qdisc);
+                list_add_tail(&q->list, &root->list);
+        }
 }
+EXPORT_SYMBOL(qdisc_list_add);
 
 void qdisc_list_del(struct Qdisc *q)
 {