Pull bugzilla-7880 into release branch

[pandora-kernel.git] / net / ipv4 / tcp_cong.c

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 86b2653..55fca18 100644 (file)
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -276,30 +276,34 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
 
 
 /*
- * Slow start (exponential increase) with
- * RFC3742 Limited Slow Start (fast linear increase) support.
+ * 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)
 {
-       int cnt = 0;
-
-       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;
 
-       if (sysctl_tcp_max_ssthresh > 0 &&
-           tp->snd_cwnd > sysctl_tcp_max_ssthresh)
-               cnt += sysctl_tcp_max_ssthresh>>1;
+       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;
+               cnt = tp->snd_cwnd;                     /* exponential increase */
 
-       /* RFC3465: We MAY increase by 2 if discovered delayed ack */
+       /* 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;
@@ -320,8 +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);