Commit 9ead9a1d authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
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[TCP] FRTO: Separated response from FRTO detection algorithm 



FRTO spurious RTO detection algorithm (RFC4138) does not include response
to a detected spurious RTO but can use different response algorithms.

Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 522e7548

net/ipv4/tcp_input.c

+10 −6
Original line number Diff line number Diff line
@@ -2467,6 +2467,15 @@ static int tcp_ack_update_window(struct sock *sk, struct tcp_sock *tp, 
	return flag;

}



/* A very conservative spurious RTO response algorithm: reduce cwnd and

 * continue in congestion avoidance.

 */

static void tcp_conservative_spur_to_response(struct tcp_sock *tp)

{

	tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);

	tcp_moderate_cwnd(tp);

}



static void tcp_process_frto(struct sock *sk, u32 prior_snd_una)

{

	struct tcp_sock *tp = tcp_sk(sk);
@@ -2488,12 +2497,7 @@ static void tcp_process_frto(struct sock *sk, u32 prior_snd_una) 
		 */

		tp->snd_cwnd = tcp_packets_in_flight(tp) + 2;

	} else {

		/* Also the second ACK after RTO advances the window.

		 * The RTO was likely spurious. Reduce cwnd and continue

		 * in congestion avoidance

		 */

		tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);

		tcp_moderate_cwnd(tp);

		tcp_conservative_spur_to_response(tp);

	}



	/* F-RTO affects on two new ACKs following RTO.