udp: secondary hash on (local port, local address)

Extends udp_table to contain a secondary hash table.

socket anchor for this second hash is free, because UDP
doesnt use skc_bind_node : We define an union to hold
both skc_bind_node & a new hlist_nulls_node udp_portaddr_node

udp_lib_get_port() inserts sockets into second hash chain
(additional cost of one atomic op)

udp_lib_unhash() deletes socket from second hash chain
(additional cost of one atomic op)

Note : No spinlock lockdep annotation is needed, because
lock for the secondary hash chain is always get after
lock for primary hash chain.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/udp.h b/include/linux/udp.h
index 5b4b5274e683..59f0ddf2d284 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -57,6 +57,7 @@ struct udp_sock {
         struct inet_sock inet;
 #define udp_port_hash           inet.sk.__sk_common.skc_u16hashes[0]
 #define udp_portaddr_hash       inet.sk.__sk_common.skc_u16hashes[1]
+#define udp_portaddr_node       inet.sk.__sk_common.skc_portaddr_node
         int              pending;       /* Any pending frames ? */
         unsigned int     corkflag;      /* Cork is required */
         __u16            encap_type;    /* Is this an Encapsulation socket? */