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tcp: fix no cwnd growth after timeout 

In commit 0f7cc9a3 "tcp: increase throughput when reordering is high",
it only allows cwnd to increase in Open state. This mistakenly disables
slow start after timeout (CA_Loss). Moreover cwnd won't grow if the
state moves from Disorder to Open later in tcp_fastretrans_alert().

Therefore the correct logic should be to allow cwnd to grow as long
as the data is received in order in Open, Loss, or even Disorder state.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Yuchung Cheng 2013-09-05 15:36:09 -07:00 committed by David S. Miller
parent 5ffd5cddd4
commit 16edfe7ee0
1 changed files with 2 additions and 4 deletions
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6
net/ipv4/tcp_input.c
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@ -3162,16 +3162,14 @@ static inline bool tcp_may_raise_cwnd(const struct sock *sk, const int flag)
/* If reordering is high then always grow cwnd whenever data is
* delivered regardless of its ordering. Otherwise stay conservative
* and only grow cwnd on in-order delivery in Open state, and retain
* cwnd in Disordered state (RFC5681). A stretched ACK with
* and only grow cwnd on in-order delivery (RFC5681). A stretched ACK w/
* new SACK or ECE mark may first advance cwnd here and later reduce
* cwnd in tcp_fastretrans_alert() based on more states.
*/
if (tcp_sk(sk)->reordering > sysctl_tcp_reordering)
return flag & FLAG_FORWARD_PROGRESS;
return inet_csk(sk)->icsk_ca_state == TCP_CA_Open &&
flag & FLAG_DATA_ACKED;
return flag & FLAG_DATA_ACKED;
}
/* Check that window update is acceptable.