net: sched: fix skb->protocol use in case of accelerated vlan path

tc code implicitly considers skb->protocol even in case of accelerated
vlan paths and expects vlan protocol type here. However, on rx path,
if the vlan header was already stripped, skb->protocol contains value
of next header. Similar situation is on tx path.

So for skbs that use skb->vlan_tci for tagging, use skb->vlan_proto instead.

Reported-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 76f402e..243b7d1 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1807,7 +1807,7 @@
 int tc_classify_compat(struct sk_buff *skb, const struct tcf_proto *tp,
 		       struct tcf_result *res)
 {
-	__be16 protocol = skb->protocol;
+	__be16 protocol = tc_skb_protocol(skb);
 	int err;
 
 	for (; tp; tp = rcu_dereference_bh(tp->next)) {