ipv6: ip6_forward: perform skb->pkt_type check at the beginning

Packets which have L2 address different from ours should be
already filtered before entering into ip6_forward().

Perform that check at the beginning to avoid processing such packets.
Signed-off-by: NLi RongQing <roy.qing.li@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/ip6_output.c

@@ -367,6 +367,9 @@ int ip6_forward(struct sk_buff *skb)
 	if (net->ipv6.devconf_all->forwarding == 0)
 		goto error;
 
+	if (skb->pkt_type != PACKET_HOST)
+		goto drop;
+
 	if (skb_warn_if_lro(skb))
 		goto drop;
 
@@ -376,9 +379,6 @@ int ip6_forward(struct sk_buff *skb)
 		goto drop;
 	}
 
-	if (skb->pkt_type != PACKET_HOST)
-		goto drop;
-
 	skb_forward_csum(skb);
 
 	/*