tcp: Fix tcp_hybla zero congestion window growth with small rho and large cwnd.
Because of rounding, in certain conditions, i.e. when in congestion
avoidance state rho is smaller than 1/128 of the current cwnd, TCP
Hybla congestion control starves and the cwnd is kept constant
forever.
This patch forces an increment by one segment after #send_cwnd calls
without increments(newreno behavior).
Signed-off-by: Daniele Lacamera <root@danielinux.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_hybla.c b/net/ipv4/tcp_hybla.c
index bfcbd14..c209e05 100644
--- a/net/ipv4/tcp_hybla.c
+++ b/net/ipv4/tcp_hybla.c
@@ -150,7 +150,11 @@
ca->snd_cwnd_cents -= 128;
tp->snd_cwnd_cnt = 0;
}
-
+ /* check when cwnd has not been incremented for a while */
+ if (increment == 0 && odd == 0 && tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+ tp->snd_cwnd++;
+ tp->snd_cwnd_cnt = 0;
+ }
/* clamp down slowstart cwnd to ssthresh value. */
if (is_slowstart)
tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
