[INET_DIAG]: Move the tcp_diag interface to the proper place

With this the previous setup is back, i.e. tcp_diag can be built as a module,
as dccp_diag and both share the infrastructure available in inet_diag.

If one selects CONFIG_INET_DIAG as module CONFIG_INET_TCP_DIAG will also be
built as a module, as will CONFIG_INET_DCCP_DIAG, if CONFIG_IP_DCCP was
selected static or as a module, if CONFIG_INET_DIAG is y, being statically
linked CONFIG_INET_TCP_DIAG will follow suit and CONFIG_INET_DCCP_DIAG will be
built in the same manner as CONFIG_IP_DCCP.

Now to aim at UDP, converting it to use inet_hashinfo, so that we can use
iproute2 for UDP sockets as well.

Ah, just to show an example of this new infrastructure working for DCCP :-)

[root@qemu ~]# ./ss -dane
State      Recv-Q Send-Q Local Address:Port  Peer Address:Port
LISTEN     0      0                  *:5001             *:*     ino:942 sk:cfd503a0
ESTAB      0      0          127.0.0.1:5001     127.0.0.1:32770 ino:943 sk:cfd50a60
ESTAB      0      0          127.0.0.1:32770    127.0.0.1:5001  ino:947 sk:cfd50700
TIME-WAIT  0      0          127.0.0.1:32769    127.0.0.1:5001  timer:(timewait,3.430ms,0) ino:0 sk:cf209620

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 3bd5109..1880ad8 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -797,25 +797,6 @@
 	}
 }
 
-static void tcp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
-			      void *_info)
-{
-	const struct tcp_sock *tp = tcp_sk(sk);
-	struct tcp_info *info = _info;
-
-	r->idiag_rqueue = tp->rcv_nxt - tp->copied_seq;
-	r->idiag_wqueue = tp->write_seq - tp->snd_una;
-	if (info != NULL)
-		tcp_get_info(sk, info);
-}
-
-static struct inet_diag_handler tcp_diag_handler = {
-	.idiag_hashinfo	 = &tcp_hashinfo,
-	.idiag_get_info	 = tcp_diag_get_info,
-	.idiag_type	 = TCPDIAG_GETSOCK,
-	.idiag_info_size = sizeof(struct tcp_info),
-};
-
 static DEFINE_SPINLOCK(inet_diag_register_lock);
 
 int inet_diag_register(const struct inet_diag_handler *h)
@@ -864,19 +845,13 @@
 		goto out;
 
 	memset(inet_diag_table, 0, inet_diag_table_size);
-
 	idiagnl = netlink_kernel_create(NETLINK_INET_DIAG, inet_diag_rcv,
 					THIS_MODULE);
 	if (idiagnl == NULL)
 		goto out_free_table;
-
-	err = inet_diag_register(&tcp_diag_handler);
-	if (err)
-		goto out_sock_release;
+	err = 0;
 out:
 	return err;
-out_sock_release:
-	sock_release(idiagnl->sk_socket);
 out_free_table:
 	kfree(inet_diag_table);
 	goto out;