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;