net: skb->dst accessors

Define three accessors to get/set dst attached to a skb

struct dst_entry *skb_dst(const struct sk_buff *skb)

void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)

void skb_dst_drop(struct sk_buff *skb)
This one should replace occurrences of :
dst_release(skb->dst)
skb->dst = NULL;

Delete skb->dst field

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/output.c b/net/dccp/output.c
index 36bcc00..c0e88c1 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -350,7 +350,7 @@
 	/* Reserve space for headers. */
 	skb_reserve(skb, sk->sk_prot->max_header);
 
-	skb->dst = dst_clone(dst);
+	skb_dst_set(skb, dst_clone(dst));
 
 	dreq = dccp_rsk(req);
 	if (inet_rsk(req)->acked)	/* increase ISS upon retransmission */