Commit 575ee714 authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
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[TCP] FRTO: Delay skb available check until it's mandatory 



No new data is needed until the first ACK comes, so no need to check
for application limitedness until then.

Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 157bfc25

net/ipv4/tcp_input.c

+11 −8
Original line number Diff line number Diff line
@@ -1265,20 +1265,15 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 
	return flag;

}



/* F-RTO can only be used if these conditions are satisfied:

 *  - there must be some unsent new data

 *  - the advertised window should allow sending it

 *  - TCP has never retransmitted anything other than head (SACK enhanced

 *    variant from Appendix B of RFC4138 is more robust here)

/* F-RTO can only be used if TCP has never retransmitted anything other than

 * head (SACK enhanced variant from Appendix B of RFC4138 is more robust here)

 */

int tcp_use_frto(struct sock *sk)

{

	const struct tcp_sock *tp = tcp_sk(sk);

	struct sk_buff *skb;



	if (!sysctl_tcp_frto || !tcp_send_head(sk) ||

		after(TCP_SKB_CB(tcp_send_head(sk))->end_seq,

		      tp->snd_una + tp->snd_wnd))

	if (!sysctl_tcp_frto)

		return 0;



	if (IsSackFrto())
@@ -2710,6 +2705,14 @@ static int tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag) 
	}



	if (tp->frto_counter == 1) {

		/* Sending of the next skb must be allowed or no FRTO */

		if (!tcp_send_head(sk) ||

		    after(TCP_SKB_CB(tcp_send_head(sk))->end_seq,

				     tp->snd_una + tp->snd_wnd)) {

			tcp_enter_frto_loss(sk, tp->frto_counter + 1, flag);

			return 1;

		}



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

		tp->frto_counter = 2;

		return 1;