[NET_SCHED] sch_prio: class statistics printing enabled

This patch adds a dump_stats callback to enable
printing of basic statistics of prio classes.
(With help of Patrick McHardy).

Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_prio.c

@@ -372,6 +372,20 @@ static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *
 	return 0;
 }
 
+static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
+				 struct gnet_dump *d)
+{
+	struct prio_sched_data *q = qdisc_priv(sch);
+	struct Qdisc *cl_q;
+
+	cl_q = q->queues[cl - 1];
+	if (gnet_stats_copy_basic(d, &cl_q->bstats) < 0 ||
+	    gnet_stats_copy_queue(d, &cl_q->qstats) < 0)
+		return -1;
+
+	return 0;
+}
+
 static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 {
 	struct prio_sched_data *q = qdisc_priv(sch);
@@ -414,6 +428,7 @@ static struct Qdisc_class_ops prio_class_ops = {
 	.bind_tcf	=	prio_bind,
 	.unbind_tcf	=	prio_put,
 	.dump		=	prio_dump_class,
+	.dump_stats	=	prio_dump_class_stats,
 };
 
 static struct Qdisc_ops prio_qdisc_ops = {