net: sched: cbq: create block for q->link.block

q->link.block is not initialized, that leads to EINVAL when one tries to
add filter there. So initialize it properly.

This can be reproduced by:
$ tc qdisc add dev eth0 root handle 1: cbq avpkt 1000 rate 1000Mbit bandwidth 1000Mbit
$ tc filter add dev eth0 parent 1: protocol ip prio 100 u32 match ip protocol 0 0x00 flowid 1:1
Reported-by: Jaroslav Aster <jaster@redhat.com>
Reported-by: Ivan Vecera <ivecera@redhat.com>
Fixes: 6529eaba ("net: sched: introduce tcf block infractructure")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Reviewed-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_cbq.c

@@ -1158,9 +1158,13 @@ static int cbq_init(struct Qdisc *sch, struct nlattr *opt)
 	if ((q->link.R_tab = qdisc_get_rtab(r, tb[TCA_CBQ_RTAB])) == NULL)
 		return -EINVAL;
 
+	err = tcf_block_get(&q->link.block, &q->link.filter_list, sch);
+	if (err)
+		goto put_rtab;
+
 	err = qdisc_class_hash_init(&q->clhash);
 	if (err < 0)
-		goto put_rtab;
+		goto put_block;
 
 	q->link.sibling = &q->link;
 	q->link.common.classid = sch->handle;
@@ -1194,6 +1198,9 @@ static int cbq_init(struct Qdisc *sch, struct nlattr *opt)
 	cbq_addprio(q, &q->link);
 	return 0;
 
+put_block:
+	tcf_block_put(q->link.block);
+
 put_rtab:
 	qdisc_put_rtab(q->link.R_tab);
 	return err;