net: sch: api: add extack support in tcf_block_get

This patch adds extack support for the function tcf_block_get 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 tcf_block_get failed.

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_htb.c b/net/sched/sch_htb.c
index 51be1b7..54e1f86 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1032,7 +1032,7 @@ static int htb_init(struct Qdisc *sch, struct nlattr *opt,
 	if (!opt)
 		return -EINVAL;
 
-	err = tcf_block_get(&q->block, &q->filter_list, sch);
+	err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
 	if (err)
 		return err;
 
@@ -1397,7 +1397,7 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
 		if (!cl)
 			goto failure;
 
-		err = tcf_block_get(&cl->block, &cl->filter_list, sch);
+		err = tcf_block_get(&cl->block, &cl->filter_list, sch, extack);
 		if (err) {
 			kfree(cl);
 			goto failure;