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>

net/sched/sch_sfq.c

@@ -149,7 +149,7 @@ static unsigned sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb)
 		break;
 	}
 	default:
-		h = (unsigned long)skb->dst ^ skb->protocol;
+		h = (unsigned long)skb_dst(skb) ^ skb->protocol;
 		h2 = (unsigned long)skb->sk;
 	}