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/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index fc79e341..319c885 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -546,7 +546,7 @@
 	if (th->rst)
 		return;
 
-	if (skb->rtable->rt_type != RTN_LOCAL)
+	if (skb_rtable(skb)->rt_type != RTN_LOCAL)
 		return;
 
 	/* Swap the send and the receive. */
@@ -1185,7 +1185,7 @@
 #endif
 
 	/* Never answer to SYNs send to broadcast or multicast */
-	if (skb->rtable->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
+	if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 		goto drop;
 
 	/* TW buckets are converted to open requests without