net: skb->rtable accessor

Define skb_rtable(const struct sk_buff *skb) accessor to get rtable from skb

Delete skb->rtable field

Setting rtable is not allowed, just set dst instead as rtable is an alias.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 77436e2..85ddad4 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -602,7 +602,7 @@
 #ifdef CONFIG_NET_IPGRE_BROADCAST
 		if (ipv4_is_multicast(iph->daddr)) {
 			/* Looped back packet, drop it! */
-			if (skb->rtable->fl.iif == 0)
+			if (skb_rtable(skb)->fl.iif == 0)
 				goto drop;
 			stats->multicast++;
 			skb->pkt_type = PACKET_BROADCAST;
@@ -704,7 +704,7 @@
 		}
 
 		if (skb->protocol == htons(ETH_P_IP)) {
-			rt = skb->rtable;
+			rt = skb_rtable(skb);
 			if ((dst = rt->rt_gateway) == 0)
 				goto tx_error_icmp;
 		}