Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 16edfe7e authored by Yuchung Cheng's avatar Yuchung Cheng Committed by David S. Miller
Browse files

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: default avatarYuchung Cheng <ycheng@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5ffd5cdd

net/ipv4/tcp_input.c

+2 −4
Original line number Diff line number Diff line
@@ -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.