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/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 1c7f400..4aae658 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -277,7 +277,7 @@
 	if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 	    !pskb_may_pull(skb, (skb_transport_offset(skb) +
 				 ((skb_transport_header(skb)[1] + 1) << 3)))) {
-		IP6_INC_STATS_BH(dev_net(skb->dst->dev), ip6_dst_idev(skb->dst),
+		IP6_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ip6_dst_idev(skb_dst(skb)),
 				 IPSTATS_MIB_INHDRERRORS);
 		kfree_skb(skb);
 		return -1;
@@ -288,7 +288,7 @@
 	dstbuf = opt->dst1;
 #endif
 
-	dst = dst_clone(skb->dst);
+	dst = dst_clone(skb_dst(skb));
 	if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) {
 		dst_release(dst);
 		skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
@@ -333,7 +333,7 @@
 	if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 	    !pskb_may_pull(skb, (skb_transport_offset(skb) +
 				 ((skb_transport_header(skb)[1] + 1) << 3)))) {
-		IP6_INC_STATS_BH(net, ip6_dst_idev(skb->dst),
+		IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 				 IPSTATS_MIB_INHDRERRORS);
 		kfree_skb(skb);
 		return -1;
@@ -343,7 +343,7 @@
 
 	if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
 	    skb->pkt_type != PACKET_HOST) {
-		IP6_INC_STATS_BH(net, ip6_dst_idev(skb->dst),
+		IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 				 IPSTATS_MIB_INADDRERRORS);
 		kfree_skb(skb);
 		return -1;
@@ -358,7 +358,7 @@
 			 * processed by own
 			 */
 			if (!addr) {
-				IP6_INC_STATS_BH(net, ip6_dst_idev(skb->dst),
+				IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 						 IPSTATS_MIB_INADDRERRORS);
 				kfree_skb(skb);
 				return -1;
@@ -384,7 +384,7 @@
 			goto unknown_rh;
 		/* Silently discard invalid RTH type 2 */
 		if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
-			IP6_INC_STATS_BH(net, ip6_dst_idev(skb->dst),
+			IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 					 IPSTATS_MIB_INHDRERRORS);
 			kfree_skb(skb);
 			return -1;
@@ -403,7 +403,7 @@
 	n = hdr->hdrlen >> 1;
 
 	if (hdr->segments_left > n) {
-		IP6_INC_STATS_BH(net, ip6_dst_idev(skb->dst),
+		IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 				 IPSTATS_MIB_INHDRERRORS);
 		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 				  ((&hdr->segments_left) -
@@ -417,7 +417,7 @@
 	if (skb_cloned(skb)) {
 		/* the copy is a forwarded packet */
 		if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
-			IP6_INC_STATS_BH(net, ip6_dst_idev(skb->dst),
+			IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 					 IPSTATS_MIB_OUTDISCARDS);
 			kfree_skb(skb);
 			return -1;
@@ -440,13 +440,13 @@
 		if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
 				     (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 				     IPPROTO_ROUTING) < 0) {
-			IP6_INC_STATS_BH(net, ip6_dst_idev(skb->dst),
+			IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 					 IPSTATS_MIB_INADDRERRORS);
 			kfree_skb(skb);
 			return -1;
 		}
-		if (!ipv6_chk_home_addr(dev_net(skb->dst->dev), addr)) {
-			IP6_INC_STATS_BH(net, ip6_dst_idev(skb->dst),
+		if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
+			IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 					 IPSTATS_MIB_INADDRERRORS);
 			kfree_skb(skb);
 			return -1;
@@ -458,7 +458,7 @@
 	}
 
 	if (ipv6_addr_is_multicast(addr)) {
-		IP6_INC_STATS_BH(net, ip6_dst_idev(skb->dst),
+		IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 				 IPSTATS_MIB_INADDRERRORS);
 		kfree_skb(skb);
 		return -1;
@@ -468,17 +468,17 @@
 	ipv6_addr_copy(addr, &ipv6_hdr(skb)->daddr);
 	ipv6_addr_copy(&ipv6_hdr(skb)->daddr, &daddr);
 
-	dst_release(xchg(&skb->dst, NULL));
+	skb_dst_drop(skb);
 	ip6_route_input(skb);
-	if (skb->dst->error) {
+	if (skb_dst(skb)->error) {
 		skb_push(skb, skb->data - skb_network_header(skb));
 		dst_input(skb);
 		return -1;
 	}
 
-	if (skb->dst->dev->flags&IFF_LOOPBACK) {
+	if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
 		if (ipv6_hdr(skb)->hop_limit <= 1) {
-			IP6_INC_STATS_BH(net, ip6_dst_idev(skb->dst),
+			IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 					 IPSTATS_MIB_INHDRERRORS);
 			icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 				    0, skb->dev);
@@ -494,7 +494,7 @@
 	return -1;
 
 unknown_rh:
-	IP6_INC_STATS_BH(net, ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
+	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS);
 	icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 			  (&hdr->type) - skb_network_header(skb));
 	return -1;
@@ -552,11 +552,11 @@
  **********************************/
 
 /*
- * Note: we cannot rely on skb->dst before we assign it in ip6_route_input().
+ * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
  */
 static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
 {
-	return skb->dst ? ip6_dst_idev(skb->dst) : __in6_dev_get(skb->dev);
+	return skb_dst(skb) ? ip6_dst_idev(skb_dst(skb)) : __in6_dev_get(skb->dev);
 }
 
 /* Router Alert as of RFC 2711 */
@@ -581,7 +581,7 @@
 {
 	const unsigned char *nh = skb_network_header(skb);
 	u32 pkt_len;
-	struct net *net = dev_net(skb->dst->dev);
+	struct net *net = dev_net(skb_dst(skb)->dev);
 
 	if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
 		LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",