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>

include/linux/skbuff.h

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index a3ae3c5..9ef6eb2 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -323,7 +323,6 @@
 	struct net_device	*dev;
 
 	union {
-		struct  dst_entry	*dst;
 		unsigned long		_skb_dst;
 	};
 #ifdef CONFIG_XFRM
@@ -426,9 +425,19 @@
 			  enum dma_data_direction dir);
 #endif
 
+static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
+{
+	return (struct dst_entry *)skb->_skb_dst;
+}
+
+static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
+{
+	skb->_skb_dst = (unsigned long)dst;
+}
+
 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
 {
-	return (struct rtable *)skb->_skb_dst;
+	return (struct rtable *)skb_dst(skb);
 }
 
 extern void kfree_skb(struct sk_buff *skb);

include/net/dst.h

diff --git a/include/net/dst.h b/include/net/dst.h
index 6be3b08..7fc409c 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -195,6 +195,12 @@
 }
 
 extern void dst_release(struct dst_entry *dst);
+static inline void skb_dst_drop(struct sk_buff *skb)
+{
+	if (skb->_skb_dst)
+		dst_release(skb_dst(skb));
+	skb->_skb_dst = 0UL;
+}
 
 /* Children define the path of the packet through the
  * Linux networking.  Thus, destinations are stackable.
@@ -246,7 +252,7 @@
 
 static inline void dst_link_failure(struct sk_buff *skb)
 {
-	struct dst_entry * dst = skb->dst;
+	struct dst_entry *dst = skb_dst(skb);
 	if (dst && dst->ops && dst->ops->link_failure)
 		dst->ops->link_failure(skb);
 }
@@ -265,13 +271,13 @@
 /* Output packet to network from transport.  */
 static inline int dst_output(struct sk_buff *skb)
 {
-	return skb->dst->output(skb);
+	return skb_dst(skb)->output(skb);
 }
 
 /* Input packet from network to transport.  */
 static inline int dst_input(struct sk_buff *skb)
 {
-	return skb->dst->input(skb);
+	return skb_dst(skb)->input(skb);
 }
 
 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)

include/net/inet6_hashtables.h

diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h
index f74665d..22c73a7 100644
--- a/include/net/inet6_hashtables.h
+++ b/include/net/inet6_hashtables.h
@@ -100,7 +100,7 @@
 
 	if (unlikely(sk = skb_steal_sock(skb)))
 		return sk;
-	else return __inet6_lookup(dev_net(skb->dst->dev), hashinfo,
+	else return __inet6_lookup(dev_net(skb_dst(skb)->dev), hashinfo,
 				   &ipv6_hdr(skb)->saddr, sport,
 				   &ipv6_hdr(skb)->daddr, ntohs(dport),
 				   inet6_iif(skb));

include/net/inet_hashtables.h

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index a44e224..d522dcf 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -385,7 +385,7 @@
 	if (unlikely(sk = skb_steal_sock(skb)))
 		return sk;
 	else
-		return __inet_lookup(dev_net(skb->dst->dev), hashinfo,
+		return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo,
 				     iph->saddr, sport,
 				     iph->daddr, dport, inet_iif(skb));
 }

include/net/ip6_route.h

diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 5f53db7..0e1b8ae 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -142,7 +142,7 @@
 
 static inline int ipv6_unicast_destination(struct sk_buff *skb)
 {
-	struct rt6_info *rt = (struct rt6_info *) skb->dst;
+	struct rt6_info *rt = (struct rt6_info *) skb_dst(skb);
 
 	return rt->rt6i_flags & RTF_LOCAL;
 }

include/net/xfrm.h

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 2e9f5c0..736bca4 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -994,7 +994,7 @@
 		return __xfrm_policy_check(sk, ndir, skb, family);
 
 	return	(!net->xfrm.policy_count[dir] && !skb->sp) ||
-		(skb->dst->flags & DST_NOPOLICY) ||
+		(skb_dst(skb)->flags & DST_NOPOLICY) ||
 		__xfrm_policy_check(sk, ndir, skb, family);
 }
 
@@ -1048,7 +1048,7 @@
 	struct net *net = dev_net(skb->dev);
 
 	return	!net->xfrm.policy_count[XFRM_POLICY_OUT] ||
-		(skb->dst->flags & DST_NOXFRM) ||
+		(skb_dst(skb)->flags & DST_NOXFRM) ||
 		__xfrm_route_forward(skb, family);
 }