From 006f582c73f4eda35e06fd323193c3df43fb3459 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ilpo=20J=C3=A4rvinen?= Date: Sat, 20 Sep 2008 21:20:20 -0700 Subject: [PATCH] tcp: convert retransmit_cnt_hint to seqno MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Main benefit in this is that we can then freely point the retransmit_skb_hint to anywhere we want to because there's no longer need to know what would be the count changes involve, and since this is really used only as a terminator, unnecessary work is one time walk at most, and if some retransmissions are necessary after that point later on, the walk is not full waste of time anyway. Since retransmit_high must be kept valid, all lost markers must ensure that. Now I also have learned how those "holes" in the rexmittable skbs can appear, mtu probe does them. So I removed the misleading comment as well. Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- include/linux/tcp.h | 2 +- include/net/tcp.h | 2 ++ net/ipv4/tcp_input.c | 34 ++++++++++++++++++++-------------- net/ipv4/tcp_output.c | 25 +++++++------------------ 4 files changed, 30 insertions(+), 33 deletions(-) diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 2e2557388e36..d7637c4b2840 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -358,7 +358,7 @@ struct tcp_sock { */ int lost_cnt_hint; - int retransmit_cnt_hint; + u32 retransmit_high; /* L-bits may be on up to this seqno */ u32 lost_retrans_low; /* Sent seq after any rxmit (lowest) */ diff --git a/include/net/tcp.h b/include/net/tcp.h index b71676326950..d0e90c50722b 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -472,6 +472,8 @@ extern void tcp_send_delayed_ack(struct sock *sk); /* tcp_input.c */ extern void tcp_cwnd_application_limited(struct sock *sk); +extern void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, + struct sk_buff *skb); /* tcp_timer.c */ extern void tcp_init_xmit_timers(struct sock *); diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 12512336dbd8..d271cc825005 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -979,17 +979,17 @@ static void tcp_update_reordering(struct sock *sk, const int metric, } } -/* RFC: This is from the original, I doubt that this is necessary at all: - * clear xmit_retrans hint if seq of this skb is beyond hint. How could we - * retransmitted past LOST markings in the first place? I'm not fully sure - * about undo and end of connection cases, which can cause R without L? - */ +/* This must be called before lost_out is incremented */ static void tcp_verify_retransmit_hint(struct tcp_sock *tp, struct sk_buff *skb) { - if ((tp->retransmit_skb_hint != NULL) && + if ((tp->retransmit_skb_hint == NULL) || before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->retransmit_skb_hint)->seq)) - tp->retransmit_skb_hint = NULL; + tp->retransmit_skb_hint = skb; + + if (!tp->lost_out || + after(TCP_SKB_CB(skb)->end_seq, tp->retransmit_high)) + tp->retransmit_high = TCP_SKB_CB(skb)->end_seq; } static void tcp_skb_mark_lost(struct tcp_sock *tp, struct sk_buff *skb) @@ -1002,6 +1002,16 @@ static void tcp_skb_mark_lost(struct tcp_sock *tp, struct sk_buff *skb) } } +void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb) +{ + tcp_verify_retransmit_hint(tp, skb); + + if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_ACKED))) { + tp->lost_out += tcp_skb_pcount(skb); + TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; + } +} + /* This procedure tags the retransmission queue when SACKs arrive. * * We have three tag bits: SACKED(S), RETRANS(R) and LOST(L). @@ -1178,13 +1188,7 @@ static void tcp_mark_lost_retrans(struct sock *sk) TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS; tp->retrans_out -= tcp_skb_pcount(skb); - /* clear lost hint */ - tp->retransmit_skb_hint = NULL; - - if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_ACKED))) { - tp->lost_out += tcp_skb_pcount(skb); - TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; - } + tcp_skb_mark_lost_uncond_verify(tp, skb); NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSTRETRANSMIT); } else { if (before(ack_seq, new_low_seq)) @@ -1890,6 +1894,7 @@ static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag) if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) { TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; tp->lost_out += tcp_skb_pcount(skb); + tp->retransmit_high = TCP_SKB_CB(skb)->end_seq; } } tcp_verify_left_out(tp); @@ -1974,6 +1979,7 @@ void tcp_enter_loss(struct sock *sk, int how) TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED; TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; tp->lost_out += tcp_skb_pcount(skb); + tp->retransmit_high = TCP_SKB_CB(skb)->end_seq; } } tcp_verify_left_out(tp); diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 11490958a096..cfae61b40c44 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1838,7 +1838,7 @@ void tcp_simple_retransmit(struct sock *sk) struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *skb; unsigned int mss = tcp_current_mss(sk, 0); - int lost = 0; + u32 prior_lost = tp->lost_out; tcp_for_write_queue(skb, sk) { if (skb == tcp_send_head(sk)) @@ -1849,17 +1849,13 @@ void tcp_simple_retransmit(struct sock *sk) TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS; tp->retrans_out -= tcp_skb_pcount(skb); } - if (!(TCP_SKB_CB(skb)->sacked & TCPCB_LOST)) { - TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; - tp->lost_out += tcp_skb_pcount(skb); - lost = 1; - } + tcp_skb_mark_lost_uncond_verify(tp, skb); } } tcp_clear_all_retrans_hints(tp); - if (!lost) + if (prior_lost == tp->lost_out) return; if (tcp_is_reno(tp)) @@ -2009,15 +2005,11 @@ void tcp_xmit_retransmit_queue(struct sock *sk) const struct inet_connection_sock *icsk = inet_csk(sk); struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *skb; - int packet_cnt; - if (tp->retransmit_skb_hint) { + if (tp->retransmit_skb_hint) skb = tp->retransmit_skb_hint; - packet_cnt = tp->retransmit_cnt_hint; - } else { + else skb = tcp_write_queue_head(sk); - packet_cnt = 0; - } /* First pass: retransmit lost packets. */ if (tp->lost_out) { @@ -2028,7 +2020,6 @@ void tcp_xmit_retransmit_queue(struct sock *sk) break; /* we could do better than to assign each time */ tp->retransmit_skb_hint = skb; - tp->retransmit_cnt_hint = packet_cnt; /* Assume this retransmit will generate * only one packet for congestion window @@ -2039,6 +2030,8 @@ void tcp_xmit_retransmit_queue(struct sock *sk) */ if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) return; + if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) + break; if (sacked & TCPCB_LOST) { if (!(sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))) { @@ -2059,10 +2052,6 @@ void tcp_xmit_retransmit_queue(struct sock *sk) inet_csk(sk)->icsk_rto, TCP_RTO_MAX); } - - packet_cnt += tcp_skb_pcount(skb); - if (packet_cnt >= tp->lost_out) - break; } } } -- 2.39.5