net_sched: remove some unnecessary checks in classful schedulers

The class argument to the ->graft(), ->leaf(), ->dump(), ->dump_stats() all
originate from either ->get() or ->walk() and are always valid.

Remove unnecessary checks.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index d5798e1..5b132c4 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -1621,29 +1621,25 @@
 {
 	struct cbq_class *cl = (struct cbq_class*)arg;
 
-	if (cl) {
-		if (new == NULL) {
-			new = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
-						&pfifo_qdisc_ops,
-						cl->common.classid);
-			if (new == NULL)
-				return -ENOBUFS;
-		} else {
+	if (new == NULL) {
+		new = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
+					&pfifo_qdisc_ops, cl->common.classid);
+		if (new == NULL)
+			return -ENOBUFS;
+	} else {
 #ifdef CONFIG_NET_CLS_ACT
-			if (cl->police == TC_POLICE_RECLASSIFY)
-				new->reshape_fail = cbq_reshape_fail;
+		if (cl->police == TC_POLICE_RECLASSIFY)
+			new->reshape_fail = cbq_reshape_fail;
 #endif
-		}
-		sch_tree_lock(sch);
-		*old = cl->q;
-		cl->q = new;
-		qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
-		qdisc_reset(*old);
-		sch_tree_unlock(sch);
-
-		return 0;
 	}
-	return -ENOENT;
+	sch_tree_lock(sch);
+	*old = cl->q;
+	cl->q = new;
+	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
+	qdisc_reset(*old);
+	sch_tree_unlock(sch);
+
+	return 0;
 }
 
 static struct Qdisc *
@@ -1651,7 +1647,7 @@
 {
 	struct cbq_class *cl = (struct cbq_class*)arg;
 
-	return cl ? cl->q : NULL;
+	return cl->q;
 }
 
 static void cbq_qlen_notify(struct Qdisc *sch, unsigned long arg)