neigh: Convert over to dst_neigh_lookup_skb().

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

net/core/neighbour.c

@@ -1201,10 +1201,23 @@ int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
 			write_unlock_bh(&neigh->lock);
 
 			rcu_read_lock();
-			/* On shaper/eql skb->dst->neighbour != neigh :( */
-			if (dst && (n2 = dst_get_neighbour_noref(dst)) != NULL)
+
+			/* Why not just use 'neigh' as-is?  The problem is that
+			 * things such as shaper, eql, and sch_teql can end up
+			 * using alternative, different, neigh objects to output
+			 * the packet in the output path.  So what we need to do
+			 * here is re-lookup the top-level neigh in the path so
+			 * we can reinject the packet there.
+			 */
+			n2 = NULL;
+			if (dst) {
+				n2 = dst_neigh_lookup_skb(dst, skb);
+				if (n2)
 					n1 = n2;
+			}
 			n1->output(n1, skb);
+			if (n2)
+				neigh_release(n2);
 			rcu_read_unlock();
 
 			write_lock_bh(&neigh->lock);