[patch 20/31] Fix TCP slow_start_after_idle sysctl

Greg KH
2007-04-11T23:00:56Z

[-- Attachment #1: fix-tcp-slow_start_after_idle-sysctl.patch --]
[-- Type: text/plain, Size: 1299 bytes --]

-stable review patch. If anyone has any objections, please let us know.

------------------
From: David Miller <davem@davemloft.net>

[TCP]: slow_start_after_idle should influence cwnd validation too

For the cases that slow_start_after_idle are meant to deal
with, it is almost a certainty that the congestion window
tests will think the connection is application limited and
we'll thus decrease the cwnd there too. This defeats the
whole point of setting slow_start_after_idle to zero.

So test it there too.

We do not cancel out the entire tcp_cwnd_validate() function
so that if the sysctl is changed we still have the validation
state maintained.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
net/ipv4/tcp_output.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -943,7 +943,8 @@ static void tcp_cwnd_validate(struct soc
if (tp->packets_out > tp->snd_cwnd_used)
tp->snd_cwnd_used = tp->packets_out;

- if ((s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto)
+ if (sysctl_tcp_slow_start_after_idle &&
+ (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto)
tcp_cwnd_application_limited(sk);
}
}

--