From b340b26454e7ba0f5d04b4bd5c4c782f1628ebe1 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Wed, 12 Aug 2015 11:18:19 -0700 Subject: [PATCH] tcp: TLP retransmits last if failed to send new packet 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 Signed-off-by: Neal Cardwell Signed-off-by: Nandita Dukkipati Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 38 ++++++++++++++++++++++---------------- 1 file changed, 22 insertions(+), 16 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 78fc89c..444ab5b 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -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); } -- 2.7.4