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tcp: TLP retransmits last if failed to send new packet

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When TLP fails to send new packet because of receive window
limit, it should fall back to retransmit the last packet instead.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yuchung Cheng 2015-08-12 11:18:19 -07:00 committed by David S. Miller
parent fcd16c0a95
commit b340b26454
1 changed files with 22 additions and 16 deletions
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38
net/ipv4/tcp_output.c
View File

@ -2149,7 +2149,7 @@ repair:
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)
@ -2235,11 +2235,19 @@ 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);
goto rearm_timer;
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. */
@ -2247,7 +2255,6 @@ void tcp_send_loss_probe(struct sock *sk)
goto rearm_timer;
/* Retransmit last segment. */
skb = tcp_write_queue_tail(sk);
if (WARN_ON(!skb))
goto rearm_timer;
@ -2262,24 +2269,23 @@ 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;
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:
if (likely(!err)) {
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;
}
tcp_rearm_rto(sk);
}