tcp: Remove TCPCT

TCPCT uses option-number 253, reserved for experimental use and should
not be used in production environments.
Further, TCPCT does not fully implement RFC 6013.

As a nice side-effect, removing TCPCT increases TCP's performance for
very short flows:

Doing an apache-benchmark with -c 100 -n 100000, sending HTTP-requests
for files of 1KB size.

before this patch:
	average (among 7 runs) of 20845.5 Requests/Second
after:
	average (among 7 runs) of 21403.6 Requests/Second

Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 10 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 763c108ee03d..ed6a7456eecd 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -90,9 +90,6 @@ struct tcp_options_received {
                 sack_ok : 4,    /* SACK seen on SYN packet              */
                 snd_wscale : 4, /* Window scaling received from sender  */
                 rcv_wscale : 4; /* Window scaling to send to receiver   */
-        u8      cookie_plus:6,  /* bytes in authenticator/cookie option */
-                cookie_out_never:1,
-                cookie_in_always:1;
         u8      num_sacks;      /* Number of SACK blocks                */
         u16     user_mss;       /* mss requested by user in ioctl       */
         u16     mss_clamp;      /* Maximal mss, negotiated at connection setup */
@@ -102,7 +99,6 @@ static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
 {
         rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
         rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
-        rx_opt->cookie_plus = 0;
 }
 
 /* This is the max number of SACKS that we'll generate and process. It's safe
@@ -320,12 +316,6 @@ struct tcp_sock {
         struct tcp_md5sig_info  __rcu *md5sig_info;
 #endif
 
-        /* When the cookie options are generated and exchanged, then this
-         * object holds a reference to them (cookie_values->kref).  Also
-         * contains related tcp_cookie_transactions fields.
-         */
-        struct tcp_cookie_values  *cookie_values;
-
 /* TCP fastopen related information */
         struct tcp_fastopen_request *fastopen_req;
         /* fastopen_rsk points to request_sock that resulted in this big