[TCP] tcp_highspeed: Fix problem observed by Xiaoliang (David) Wei

When snd_cwnd is smaller than 38 and the connection is in
congestion avoidance phase (snd_cwnd > snd_ssthresh), the snd_cwnd
seems to stop growing.

The additive increase was confused because C array's are 0 based.

Signed-off-by: Stephen Hemminger <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

diff --git a/net/ipv4/tcp_highspeed.c b/net/ipv4/tcp_highspeed.c
index b72fa55dfb84d114484bf6f7d1b4751449d9c4e3..ba7c63ca5bb10838f9e81a64b81cf9131be1a3f2 100644 (file)
--- a/net/ipv4/tcp_highspeed.c
+++ b/net/ipv4/tcp_highspeed.c
@@ -135,7 +135,8 @@ static void hstcp_cong_avoid(struct sock *sk, u32 adk, u32 rtt,
 
                /* Do additive increase */
                if (tp->snd_cwnd < tp->snd_cwnd_clamp) {
-                       tp->snd_cwnd_cnt += ca->ai;
+                       /* cwnd = cwnd + a(w) / cwnd */
+                       tp->snd_cwnd_cnt += ca->ai + 1;
                        if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
                                tp->snd_cwnd_cnt -= tp->snd_cwnd;
                                tp->snd_cwnd++;