net: sched: avoid duplicates in classes dump

This is a follow up of commit ea327469 ("net: sched: avoid
duplicates in qdisc dump") which has fixed the issue only for the qdisc
dump.

The duplicate printing also occurs when dumping the classes via
  tc class show dev eth0

Fixes: 59cc1f61 ("net: sched: convert qdisc linked list to hashtable")
Signed-off-by: Maximilian Heyne <mheyne@amazon.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_api.c

@@ -2168,7 +2168,7 @@ static int tc_dump_tclass_qdisc(struct Qdisc *q, struct sk_buff *skb,
 
 static int tc_dump_tclass_root(struct Qdisc *root, struct sk_buff *skb,
 			       struct tcmsg *tcm, struct netlink_callback *cb,
-			       int *t_p, int s_t)
+			       int *t_p, int s_t, bool recur)
 {
 	struct Qdisc *q;
 	int b;
@@ -2179,7 +2179,7 @@ static int tc_dump_tclass_root(struct Qdisc *root, struct sk_buff *skb,
 	if (tc_dump_tclass_qdisc(root, skb, tcm, cb, t_p, s_t) < 0)
 		return -1;
 
-	if (!qdisc_dev(root))
+	if (!qdisc_dev(root) || !recur)
 		return 0;
 
 	if (tcm->tcm_parent) {
@@ -2214,13 +2214,13 @@ static int tc_dump_tclass(struct sk_buff *skb, struct netlink_callback *cb)
 	s_t = cb->args[0];
 	t = 0;
 
-	if (tc_dump_tclass_root(dev->qdisc, skb, tcm, cb, &t, s_t) < 0)
+	if (tc_dump_tclass_root(dev->qdisc, skb, tcm, cb, &t, s_t, true) < 0)
 		goto done;
 
 	dev_queue = dev_ingress_queue(dev);
 	if (dev_queue &&
 	    tc_dump_tclass_root(dev_queue->qdisc_sleeping, skb, tcm, cb,
-				&t, s_t) < 0)
+				&t, s_t, false) < 0)
 		goto done;
 
 done: