net/sched: Remove unnecessary WARNING condition for empty child qdisc in htb_activate

The WARN_ON trigger based on !cl->leaf.q->q.qlen is unnecessary in
htb_activate. htb_dequeue_tree already accounts for that scenario.

Fixes: 1da177e ("Linux-2.6.12-rc2")
Signed-off-by: William Liu <[email protected]>
Reviewed-by: Savino Dicanosa <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: BitsByWill

net/sched/sch_htb.c

@@ -592,7 +592,7 @@ htb_change_class_mode(struct htb_sched *q, struct htb_class *cl, s64 *diff)
  */
 static inline void htb_activate(struct htb_sched *q, struct htb_class *cl)
 {
-	WARN_ON(cl->level || !cl->leaf.q || !cl->leaf.q->q.qlen);
+	WARN_ON(cl->level || !cl->leaf.q);
 
 	if (!cl->prio_activity) {
 		cl->prio_activity = 1 << cl->prio;