[IPV6]: Introduce inet6_timewait_sock

Out of tcp6_timewait_sock, that now is just an aggregation of
inet_timewait_sock and inet6_timewait_sock, using tw_ipv6_offset in struct
inet_timewait_sock, that is common to the IPv6 transport protocols that use
timewait sockets, like DCCP and TCP.

tw_ipv6_offset plays the struct inet_sock pinfo6 role, i.e. for the generic
code to find the IPv6 area in a timewait sock.

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 3ce73b1..c499081 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -112,12 +112,12 @@
 		r->idiag_inode = 0;
 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
 		if (r->idiag_family == AF_INET6) {
-			const struct tcp6_timewait_sock *tcp6tw = tcp6_twsk(sk);
+			const struct inet6_timewait_sock *tw6 = inet6_twsk(sk);
 
 			ipv6_addr_copy((struct in6_addr *)r->id.idiag_src,
-				       &tcp6tw->tw_v6_rcv_saddr);
+				       &tw6->tw_v6_rcv_saddr);
 			ipv6_addr_copy((struct in6_addr *)r->id.idiag_dst,
-				       &tcp6tw->tw_v6_daddr);
+				       &tw6->tw_v6_daddr);
 		}
 #endif
 		nlh->nlmsg_len = skb->tail - b;