net: sch: api: add extack support in qdisc_create_dflt

This patch adds extack support for the function qdisc_create_dflt which is
a common used function in the tc subsystem. Callers which are interested
in the receiving error can assign extack to get a more detailed
information why qdisc_create_dflt failed. The function qdisc_create_dflt
will also call an init callback which can fail by any per-qdisc specific
handling.

Cc: David Ahern <dsahern@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index 6ab5850..bb1a9c1 100644
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -480,8 +480,8 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 	cl->common.classid = classid;
 	cl->deficit = lmax;
 
-	cl->qdisc = qdisc_create_dflt(sch->dev_queue,
-				      &pfifo_qdisc_ops, classid);
+	cl->qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
+				      classid, NULL);
 	if (cl->qdisc == NULL)
 		cl->qdisc = &noop_qdisc;
 
@@ -601,8 +601,8 @@ static int qfq_graft_class(struct Qdisc *sch, unsigned long arg,
 	struct qfq_class *cl = (struct qfq_class *)arg;
 
 	if (new == NULL) {
-		new = qdisc_create_dflt(sch->dev_queue,
-					&pfifo_qdisc_ops, cl->common.classid);
+		new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
+					cl->common.classid, NULL);
 		if (new == NULL)
 			new = &noop_qdisc;
 	}