net: Embed hh_cache inside of struct neighbour.

Now that there is a one-to-one correspondance between neighbour
and hh_cache entries, we no longer need:

1) dynamic allocation
2) attachment to dst->hh
3) refcounting

Initialization of the hh_cache entry is indicated by hh_len
being non-zero, and such initialization is always done with
the neighbour's lock held as a writer.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 5 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 54119d5aae8..a621b96aed1 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -182,6 +182,7 @@ static inline int ip_finish_output2(struct sk_buff *skb)
 	struct rtable *rt = (struct rtable *)dst;
 	struct net_device *dev = dst->dev;
 	unsigned int hh_len = LL_RESERVED_SPACE(dev);
+	struct neighbour *neigh;
 
 	if (rt->rt_type == RTN_MULTICAST) {
 		IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len);
@@ -203,11 +204,14 @@ static inline int ip_finish_output2(struct sk_buff *skb)
 		skb = skb2;
 	}
 
-	if (dst->hh)
-		return neigh_hh_output(dst->hh, skb);
-	else if (dst->neighbour)
-		return dst->neighbour->output(skb);
-
+	neigh = dst->neighbour;
+	if (neigh) {
+		struct hh_cache *hh = &neigh->hh;
+		if (hh->hh_len)
+			return neigh_hh_output(hh, skb);
+		else
+			return dst->neighbour->output(skb);
+	}
 	if (net_ratelimit())
 		printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
 	kfree_skb(skb);