[TCP] Highspeed: Limited slow-start is nowadays in tcp_slow_start

Reuse limited slow-start (RFC3742) included into tcp_cong instead
of having another implementation in High Speed TCP.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_highspeed.c

@@ -97,10 +97,6 @@ struct hstcp {
 	u32	ai;
 };
 
-static int max_ssthresh = 100;
-module_param(max_ssthresh, int, 0644);
-MODULE_PARM_DESC(max_ssthresh, "limited slow start threshold (RFC3742)");
-
 static void hstcp_init(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
@@ -122,23 +118,9 @@ static void hstcp_cong_avoid(struct sock *sk, u32 adk, u32 rtt,
 	if (!tcp_is_cwnd_limited(sk, in_flight))
 		return;
 
-	if (tp->snd_cwnd <= tp->snd_ssthresh) {
-		/* RFC3742: limited slow start
-		 * the window is increased by 1/K MSS for each arriving ACK,
-		 * for K = int(cwnd/(0.5 max_ssthresh))
-		 */
-		if (max_ssthresh > 0 && tp->snd_cwnd > max_ssthresh) {
-			u32 k = max(tp->snd_cwnd / (max_ssthresh >> 1), 1U);
-			if (++tp->snd_cwnd_cnt >= k) {
-				if (tp->snd_cwnd < tp->snd_cwnd_clamp)
-					tp->snd_cwnd++;
-				tp->snd_cwnd_cnt = 0;
-			}
-		} else {
-			if (tp->snd_cwnd < tp->snd_cwnd_clamp)
-				tp->snd_cwnd++;
-		}
-	} else {
+	if (tp->snd_cwnd <= tp->snd_ssthresh)
+		tcp_slow_start(tp);
+	else {
 		/* Update AIMD parameters.
 		 *
 		 * We want to guarantee that: