udp: add missing rehash callback to udplite

After commit 4cdeeee925 ("net: udp: prefer listeners bound to an
address"), UDP-Lite only works when specifying a local address for
the sockets.

This is related to the problem addressed in the commit 719f835853
("udp: add rehash on connect()"). Moreover, __udp4_lib_lookup() now
looks for a socket immediately in the secondary hash table.

The issue was found with LTP/network tests (UDP-Lite test-cases).

Fixes: 4cdeeee925 ("net: udp: prefer listeners bound to an address")
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp.c

@@ -1926,7 +1926,7 @@ void udp_lib_rehash(struct sock *sk, u16 newhash)
 }
 EXPORT_SYMBOL(udp_lib_rehash);
 
-static void udp_v4_rehash(struct sock *sk)
+void udp_v4_rehash(struct sock *sk)
 {
 	u16 new_hash = ipv4_portaddr_hash(sock_net(sk),
 					  inet_sk(sk)->inet_rcv_saddr,

net/ipv4/udp_impl.h

@@ -10,6 +10,7 @@ int __udp4_lib_rcv(struct sk_buff *, struct udp_table *, int);
 int __udp4_lib_err(struct sk_buff *, u32, struct udp_table *);
 
 int udp_v4_get_port(struct sock *sk, unsigned short snum);
+void udp_v4_rehash(struct sock *sk);
 
 int udp_setsockopt(struct sock *sk, int level, int optname,
 		   char __user *optval, unsigned int optlen);

net/ipv4/udplite.c

@@ -53,6 +53,7 @@ struct proto 	udplite_prot = {
 	.sendpage	   = udp_sendpage,
 	.hash		   = udp_lib_hash,
 	.unhash		   = udp_lib_unhash,
+	.rehash		   = udp_v4_rehash,
 	.get_port	   = udp_v4_get_port,
 	.memory_allocated  = &udp_memory_allocated,
 	.sysctl_mem	   = sysctl_udp_mem,