1 files changed, 29 insertions, 16 deletions

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 34ae3f13483a..86b26539e54b 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -12,6 +12,8 @@
 #include <linux/list.h>
 #include <net/tcp.h>
 
+int sysctl_tcp_max_ssthresh = 0;
+
 static DEFINE_SPINLOCK(tcp_cong_list_lock);
 static LIST_HEAD(tcp_cong_list);
 
@@ -124,7 +126,7 @@ int tcp_set_default_congestion_control(const char *name)
 #endif
 
 	if (ca) {
-		ca->non_restricted = 1;	/* default is always allowed */
+		ca->flags |= TCP_CONG_NON_RESTRICTED;	/* default is always allowed */
 		list_move(&ca->list, &tcp_cong_list);
 		ret = 0;
 	}
@@ -179,7 +181,7 @@ void tcp_get_allowed_congestion_control(char *buf, size_t maxlen)
 	*buf = '\0';
 	rcu_read_lock();
 	list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
-		if (!ca->non_restricted)
+		if (!(ca->flags & TCP_CONG_NON_RESTRICTED))
 			continue;
 		offs += snprintf(buf + offs, maxlen - offs,
 				 "%s%s",
@@ -210,16 +212,16 @@ int tcp_set_allowed_congestion_control(char *val)
 		}
 	}
 
-	/* pass 2 clear */
+	/* pass 2 clear old values */
 	list_for_each_entry_rcu(ca, &tcp_cong_list, list)
-		ca->non_restricted = 0;
+		ca->flags &= ~TCP_CONG_NON_RESTRICTED;
 
 	/* pass 3 mark as allowed */
 	while ((name = strsep(&val, " ")) && *name) {
 		ca = tcp_ca_find(name);
 		WARN_ON(!ca);
 		if (ca)
-			ca->non_restricted = 1;
+			ca->flags |= TCP_CONG_NON_RESTRICTED;
 	}
 out:
 	spin_unlock(&tcp_cong_list_lock);
@@ -254,7 +256,7 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
 	if (!ca)
 		err = -ENOENT;
 
-	else if (!(ca->non_restricted || capable(CAP_NET_ADMIN)))
+	else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || capable(CAP_NET_ADMIN)))
 		err = -EPERM;
 
 	else if (!try_module_get(ca->owner))
@@ -274,10 +276,13 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
 
 
 /*
- * Linear increase during slow start
+ * Slow start (exponential increase) with
+ * RFC3742 Limited Slow Start (fast linear increase) support.
  */
 void tcp_slow_start(struct tcp_sock *tp)
 {
+	int cnt = 0;
+
 	if (sysctl_tcp_abc) {
 		/* RFC3465: Slow Start
 		 * TCP sender SHOULD increase cwnd by the number of
@@ -286,17 +291,25 @@ void tcp_slow_start(struct tcp_sock *tp)
 		 */
 		if (tp->bytes_acked < tp->mss_cache)
 			return;
-
-		/* We MAY increase by 2 if discovered delayed ack */
-		if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache) {
-			if (tp->snd_cwnd < tp->snd_cwnd_clamp)
-				tp->snd_cwnd++;
-		}
 	}
+
+	if (sysctl_tcp_max_ssthresh > 0 &&
+	    tp->snd_cwnd > sysctl_tcp_max_ssthresh)
+		cnt += sysctl_tcp_max_ssthresh>>1;
+	else
+		cnt += tp->snd_cwnd;
+
+	/* RFC3465: We MAY increase by 2 if discovered delayed ack */
+	if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache)
+		cnt <<= 1;
 	tp->bytes_acked = 0;
 
-	if (tp->snd_cwnd < tp->snd_cwnd_clamp)
-		tp->snd_cwnd++;
+	tp->snd_cwnd_cnt += cnt;
+	while (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+		tp->snd_cwnd_cnt -= tp->snd_cwnd;
+		if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+			tp->snd_cwnd++;
+	}
 }
 EXPORT_SYMBOL_GPL(tcp_slow_start);
 
@@ -358,8 +371,8 @@ u32 tcp_reno_min_cwnd(const struct sock *sk)
 EXPORT_SYMBOL_GPL(tcp_reno_min_cwnd);
 
 struct tcp_congestion_ops tcp_reno = {
+	.flags		= TCP_CONG_NON_RESTRICTED,
 	.name		= "reno",
-	.non_restricted = 1,
 	.owner		= THIS_MODULE,
 	.ssthresh	= tcp_reno_ssthresh,
 	.cong_avoid	= tcp_reno_cong_avoid,