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/security/selinux/xfrm.c b/security/selinux/xfrm.c
index c0eb720..72b1845 100644
--- a/security/selinux/xfrm.c
+++ b/security/selinux/xfrm.c
@@ -447,7 +447,7 @@
 	struct dst_entry *dst;
 	int rc = 0;
 
-	dst = skb->dst;
+	dst = skb_dst(skb);
 
 	if (dst) {
 		struct dst_entry *dst_test;