net: Do delayed neigh confirmation.

When a dst_confirm() happens, mark the confirmation as pending in the
dst.  Then on the next packet out, when we have the neigh in-hand, do
the update.

This removes the dependency in dst_confirm() of dst's having an
attached neigh.

While we're here, remove the explicit 'dst' NULL check, all except 2
or 3 call sites ensure it's not NULL.  So just fix those cases up.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/dst.h b/include/net/dst.h
index f0bf3b8..84e7a3f 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -51,7 +51,7 @@
 	int			(*input)(struct sk_buff *);
 	int			(*output)(struct sk_buff *);
 
-	int			flags;
+	unsigned short		flags;
 #define DST_HOST		0x0001
 #define DST_NOXFRM		0x0002
 #define DST_NOPOLICY		0x0004
@@ -62,6 +62,8 @@
 #define DST_FAKE_RTABLE		0x0080
 #define DST_XFRM_TUNNEL		0x0100
 
+	unsigned short		pending_confirm;
+
 	short			error;
 	short			obsolete;
 	unsigned short		header_len;	/* more space at head required */
@@ -371,7 +373,8 @@
 
 extern int dst_discard(struct sk_buff *skb);
 extern void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
-		       int initial_ref, int initial_obsolete, int flags);
+		       int initial_ref, int initial_obsolete,
+		       unsigned short flags);
 extern void __dst_free(struct dst_entry *dst);
 extern struct dst_entry *dst_destroy(struct dst_entry *dst);
 
@@ -395,14 +398,24 @@
 
 static inline void dst_confirm(struct dst_entry *dst)
 {
-	if (dst) {
-		struct neighbour *n;
+	dst->pending_confirm = 1;
+}
 
-		rcu_read_lock();
-		n = dst_get_neighbour_noref(dst);
-		neigh_confirm(n);
-		rcu_read_unlock();
+static inline int dst_neigh_output(struct dst_entry *dst, struct neighbour *n,
+				   struct sk_buff *skb)
+{
+	struct hh_cache *hh;
+
+	if (unlikely(dst->pending_confirm)) {
+		n->confirmed = jiffies;
+		dst->pending_confirm = 0;
 	}
+
+	hh = &n->hh;
+	if ((n->nud_state & NUD_CONNECTED) && hh->hh_len)
+		return neigh_hh_output(hh, skb);
+	else
+		return n->output(n, skb);
 }
 
 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)