X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=net%2Fipv4%2Ftcp_cong.c;h=55fca1820c344d7bb900e0ab486ff627c951f924;hb=d06fc1d9b5518582f4982f908e820f2303d1eece;hp=34ae3f13483a6e37b65402e3318bd635b716e460;hpb=12a5a712123b81a8ba0bc486e2384a375c00f095;p=linux-2.6

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 34ae3f1348..55fca1820c 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))
@@ -274,29 +276,44 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
 
 
 /*
- * Linear increase during slow start
+ * Slow start is used when congestion window is less than slow start
+ * threshold. This version implements the basic RFC2581 version
+ * and optionally supports:
+ * 	RFC3742 Limited Slow Start  	  - growth limited to max_ssthresh
+ *	RFC3465 Appropriate Byte Counting - growth limited by bytes acknowledged
  */
 void tcp_slow_start(struct tcp_sock *tp)
 {
-	if (sysctl_tcp_abc) {
-		/* RFC3465: Slow Start
-		 * TCP sender SHOULD increase cwnd by the number of
-		 * previously unacknowledged bytes ACKed by each incoming
-		 * acknowledgment, provided the increase is not more than L
-		 */
-		if (tp->bytes_acked < tp->mss_cache)
-			return;
+	int cnt; /* increase in packets */
+
+	/* RFC3465: ABC Slow start
+	 * Increase only after a full MSS of bytes is acked
+	 *
+	 * TCP sender SHOULD increase cwnd by the number of
+	 * previously unacknowledged bytes ACKed by each incoming
+	 * acknowledgment, provided the increase is not more than L
+	 */
+	if (sysctl_tcp_abc && 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;	/* limited slow start */
+	else
+		cnt = tp->snd_cwnd;			/* exponential increase */
+
+	/* RFC3465: ABC
+	 * 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);
 
@@ -307,8 +324,7 @@ EXPORT_SYMBOL_GPL(tcp_slow_start);
 /* This is Jacobson's slow start and congestion avoidance.
  * SIGCOMM '88, p. 328.
  */
-void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 rtt, u32 in_flight,
-			 int flag)
+void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight, int flag)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
@@ -358,8 +374,8 @@ 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,