udp: bind() optimisation

UDP bind() can be O(N^2) in some pathological cases.

Thanks to secondary hash tables, we can make it O(N)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/udp.h b/include/linux/udp.h
index 59f0ddf..03f72a2 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -88,6 +88,12 @@
 	return (struct udp_sock *)sk;
 }
 
+#define udp_portaddr_for_each_entry(__sk, node, list) \
+	hlist_nulls_for_each_entry(__sk, node, list, __sk_common.skc_portaddr_node)
+
+#define udp_portaddr_for_each_entry_rcu(__sk, node, list) \
+	hlist_nulls_for_each_entry_rcu(__sk, node, list, __sk_common.skc_portaddr_node)
+
 #define IS_UDPLITE(__sk) (udp_sk(__sk)->pcflag)
 
 #endif