[INET]: Generalise tcp_tw_bucket, aka TIME_WAIT sockets

This paves the way to generalise the rest of the sock ID lookup
routines and saves some bytes in TCPv4 TIME_WAIT sockets on distro
kernels (where IPv6 is always built as a module):

[root@qemu ~]# grep tw_sock /proc/slabinfo
tw_sock_TCPv6  0  0  128  31  1
tw_sock_TCP    0  0   96  41  1
[root@qemu ~]#

Now if a protocol wants to use the TIME_WAIT generic infrastructure it
only has to set the sk_prot->twsk_obj_size field with the size of its
inet_timewait_sock derived sock and proto_register will create
sk_prot->twsk_slab, for now its only for INET sockets, but we can
introduce timewait_sock later if some non INET transport protocolo
wants to use this stuff.

Next changesets will take advantage of this new infrastructure to
generalise even more TCP code.

[acme@toy net-2.6.14]$ grep built-in /tmp/before.size /tmp/after.size
/tmp/before.size: 188646   11764    5068  205478   322a6 net/ipv4/built-in.o
/tmp/after.size:  188144   11764    5068  204976   320b0 net/ipv4/built-in.o
[acme@toy net-2.6.14]$

Tested with both IPv4 & IPv6 (::1 (localhost) & ::ffff:172.20.0.1
(qemu host)).

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 4 deletions

diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
index 1a89a03c449b..6f2d6f2276b9 100644
--- a/net/ipv4/tcp_diag.c
+++ b/net/ipv4/tcp_diag.c
@@ -81,7 +81,7 @@ static int tcpdiag_fill(struct sk_buff *skb, struct sock *sk,
         r->id.tcpdiag_cookie[1] = (u32)(((unsigned long)sk >> 31) >> 1);
 
         if (r->tcpdiag_state == TCP_TIME_WAIT) {
-                struct tcp_tw_bucket *tw = (struct tcp_tw_bucket*)sk;
+                const struct inet_timewait_sock *tw = inet_twsk(sk);
                 long tmo = tw->tw_ttd - jiffies;
                 if (tmo < 0)
                         tmo = 0;
@@ -99,10 +99,12 @@ static int tcpdiag_fill(struct sk_buff *skb, struct sock *sk,
                 r->tcpdiag_inode = 0;
 #ifdef CONFIG_IP_TCPDIAG_IPV6
                 if (r->tcpdiag_family == AF_INET6) {
+                        const struct tcp6_timewait_sock *tcp6tw = tcp6_twsk(sk);
+
                         ipv6_addr_copy((struct in6_addr *)r->id.tcpdiag_src,
-                                       &tw->tw_v6_rcv_saddr);
+                                       &tcp6tw->tw_v6_rcv_saddr);
                         ipv6_addr_copy((struct in6_addr *)r->id.tcpdiag_dst,
-                                       &tw->tw_v6_daddr);
+                                       &tcp6tw->tw_v6_daddr);
                 }
 #endif
                 nlh->nlmsg_len = skb->tail - b;
@@ -239,7 +241,7 @@ static int tcpdiag_get_exact(struct sk_buff *in_skb, const struct nlmsghdr *nlh)
 out:
         if (sk) {
                 if (sk->sk_state == TCP_TIME_WAIT)
-                        tcp_tw_put((struct tcp_tw_bucket*)sk);
+                        inet_twsk_put((struct inet_timewait_sock *)sk);
                 else
                         sock_put(sk);
         }