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, 4 insertions, 52 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 9b6460055df5..0a97add2ab74 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -454,7 +454,6 @@ out:
 static int tcp_v6_send_synack(struct sock *sk, struct dst_entry *dst,
                               struct flowi6 *fl6,
                               struct request_sock *req,
-                              struct request_values *rvp,
                               u16 queue_mapping)
 {
         struct inet6_request_sock *treq = inet6_rsk(req);
@@ -466,7 +465,7 @@ static int tcp_v6_send_synack(struct sock *sk, struct dst_entry *dst,
         if (!dst && (dst = inet6_csk_route_req(sk, fl6, req)) == NULL)
                 goto done;
 
-        skb = tcp_make_synack(sk, dst, req, rvp, NULL);
+        skb = tcp_make_synack(sk, dst, req, NULL);
 
         if (skb) {
                 __tcp_v6_send_check(skb, &treq->loc_addr, &treq->rmt_addr);
@@ -481,13 +480,12 @@ done:
         return err;
 }
 
-static int tcp_v6_rtx_synack(struct sock *sk, struct request_sock *req,
-                             struct request_values *rvp)
+static int tcp_v6_rtx_synack(struct sock *sk, struct request_sock *req)
 {
         struct flowi6 fl6;
         int res;
 
-        res = tcp_v6_send_synack(sk, NULL, &fl6, req, rvp, 0);
+        res = tcp_v6_send_synack(sk, NULL, &fl6, req, 0);
         if (!res)
                 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS);
         return res;
@@ -940,9 +938,7 @@ static struct sock *tcp_v6_hnd_req(struct sock *sk,struct sk_buff *skb)
  */
 static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 {
-        struct tcp_extend_values tmp_ext;
         struct tcp_options_received tmp_opt;
-        const u8 *hash_location;
         struct request_sock *req;
         struct inet6_request_sock *treq;
         struct ipv6_pinfo *np = inet6_sk(sk);
@@ -980,50 +976,7 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
         tcp_clear_options(&tmp_opt);
         tmp_opt.mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr);
         tmp_opt.user_mss = tp->rx_opt.user_mss;
-        tcp_parse_options(skb, &tmp_opt, &hash_location, 0, NULL);
-
-        if (tmp_opt.cookie_plus > 0 &&
-            tmp_opt.saw_tstamp &&
-            !tp->rx_opt.cookie_out_never &&
-            (sysctl_tcp_cookie_size > 0 ||
-             (tp->cookie_values != NULL &&
-              tp->cookie_values->cookie_desired > 0))) {
-                u8 *c;
-                u32 *d;
-                u32 *mess = &tmp_ext.cookie_bakery[COOKIE_DIGEST_WORDS];
-                int l = tmp_opt.cookie_plus - TCPOLEN_COOKIE_BASE;
-
-                if (tcp_cookie_generator(&tmp_ext.cookie_bakery[0]) != 0)
-                        goto drop_and_free;
-
-                /* Secret recipe starts with IP addresses */
-                d = (__force u32 *)&ipv6_hdr(skb)->daddr.s6_addr32[0];
-                *mess++ ^= *d++;
-                *mess++ ^= *d++;
-                *mess++ ^= *d++;
-                *mess++ ^= *d++;
-                d = (__force u32 *)&ipv6_hdr(skb)->saddr.s6_addr32[0];
-                *mess++ ^= *d++;
-                *mess++ ^= *d++;
-                *mess++ ^= *d++;
-                *mess++ ^= *d++;
-
-                /* plus variable length Initiator Cookie */
-                c = (u8 *)mess;
-                while (l-- > 0)
-                        *c++ ^= *hash_location++;
-
-                want_cookie = false;    /* not our kind of cookie */
-                tmp_ext.cookie_out_never = 0; /* false */
-                tmp_ext.cookie_plus = tmp_opt.cookie_plus;
-        } else if (!tp->rx_opt.cookie_in_always) {
-                /* redundant indications, but ensure initialization. */
-                tmp_ext.cookie_out_never = 1; /* true */
-                tmp_ext.cookie_plus = 0;
-        } else {
-                goto drop_and_free;
-        }
-        tmp_ext.cookie_in_always = tp->rx_opt.cookie_in_always;
+        tcp_parse_options(skb, &tmp_opt, 0, NULL);
 
         if (want_cookie && !tmp_opt.saw_tstamp)
                 tcp_clear_options(&tmp_opt);
@@ -1101,7 +1054,6 @@ have_isn:
                 goto drop_and_release;
 
         if (tcp_v6_send_synack(sk, dst, &fl6, req,
-                               (struct request_values *)&tmp_ext,
                                skb_get_queue_mapping(skb)) ||
             want_cookie)
                 goto drop_and_free;