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

Commit 5bbbcc00 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'tcp-loss-probe' 



Yuchung Cheng says:

====================
minor tail loss probe improvements

This patch series enhance the tail loss probe (TLP) on some error
conditions. When TLP fails to send a probe, it will no longer
extend the RTO. When it fails to send a new packet because of
receiver window limit, it'll try to retransmit the last packet.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 646244b2 b340b264

net/ipv4/tcp_output.c

+23 −18
Original line number Diff line number Diff line
@@ -2149,7 +2149,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 
		tcp_cwnd_validate(sk, is_cwnd_limited);

		return false;

	}

	return (push_one == 2) || (!tp->packets_out && tcp_send_head(sk));

	return !tp->packets_out && tcp_send_head(sk);

}



bool tcp_schedule_loss_probe(struct sock *sk)
@@ -2226,7 +2226,7 @@ static bool skb_still_in_host_queue(const struct sock *sk, 
	return false;

}



/* When probe timeout (PTO) fires, send a new segment if one exists, else

/* When probe timeout (PTO) fires, try send a new segment if possible, else

 * retransmit the last segment.

 */

void tcp_send_loss_probe(struct sock *sk)
@@ -2235,19 +2235,26 @@ void tcp_send_loss_probe(struct sock *sk) 
	struct sk_buff *skb;

	int pcount;

	int mss = tcp_current_mss(sk);

	int err = -1;



	if (tcp_send_head(sk)) {

		err = tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC);

	skb = tcp_send_head(sk);

	if (skb) {

		if (tcp_snd_wnd_test(tp, skb, mss)) {

			pcount = tp->packets_out;

			tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC);

			if (tp->packets_out > pcount)

				goto probe_sent;

			goto rearm_timer;

		}

		skb = tcp_write_queue_prev(sk, skb);

	} else {

		skb = tcp_write_queue_tail(sk);

	}



	/* At most one outstanding TLP retransmission. */

	if (tp->tlp_high_seq)

		goto rearm_timer;



	/* Retransmit last segment. */

	skb = tcp_write_queue_tail(sk);

	if (WARN_ON(!skb))

		goto rearm_timer;
@@ -2262,26 +2269,24 @@ void tcp_send_loss_probe(struct sock *sk) 
		if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss,

					  GFP_ATOMIC)))

			goto rearm_timer;

		skb = tcp_write_queue_tail(sk);

		skb = tcp_write_queue_next(sk, skb);

	}



	if (WARN_ON(!skb || !tcp_skb_pcount(skb)))

		goto rearm_timer;



	err = __tcp_retransmit_skb(sk, skb);

	if (__tcp_retransmit_skb(sk, skb))

		goto rearm_timer;



	/* Record snd_nxt for loss detection. */

	if (likely(!err))

	tp->tlp_high_seq = tp->snd_nxt;



probe_sent:

	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSSPROBES);

	/* Reset s.t. tcp_rearm_rto will restart timer from now */

	inet_csk(sk)->icsk_pending = 0;

rearm_timer:

	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,

				  inet_csk(sk)->icsk_rto,

				  TCP_RTO_MAX);



	if (likely(!err))

		NET_INC_STATS_BH(sock_net(sk),

				 LINUX_MIB_TCPLOSSPROBES);

	tcp_rearm_rto(sk);

}



/* Push out any pending frames which were held back due to