From fbd52eb2bd17bd3468974aa2fdce140f0cd32fc7 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ilpo=20J=E4rvinen?= Date: Sat, 10 Nov 2007 21:24:19 -0800 Subject: [PATCH] [TCP]: Split SACK FRTO flag clearing (fixes FRTO corner case bug) MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit In case we run out of mem when fragmenting, the clearing of FLAG_ONLY_ORIG_SACKED might get missed which then feeds FRTO with false information. Move clearing outside skb processing loop so that it will get executed even if the skb loop terminates prematurely due to out-of-mem. Besides, now the core of the loop truly deals with a single skb only, which also enables creation a more self-contained of tcp_sacktag_one later on. In addition, small reorganization of if branches was made. Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 35 +++++++++++++++++------------------ 1 file changed, 17 insertions(+), 18 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 84bcdc94dfa9..20c9440ab85e 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1444,12 +1444,17 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ tp->retransmit_skb_hint = NULL; } } else { - /* New sack for not retransmitted frame, - * which was in hole. It is reordering. - */ - if (!(sacked & TCPCB_RETRANS) && - fack_count < prior_fackets) - reord = min(fack_count, reord); + if (!(sacked & TCPCB_RETRANS)) { + /* New sack for not retransmitted frame, + * which was in hole. It is reordering. + */ + if (fack_count < prior_fackets) + reord = min(fack_count, reord); + + /* SACK enhanced F-RTO (RFC4138; Appendix B) */ + if (!after(TCP_SKB_CB(skb)->end_seq, tp->frto_highmark)) + flag |= FLAG_ONLY_ORIG_SACKED; + } if (sacked & TCPCB_LOST) { TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST; @@ -1458,18 +1463,6 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ /* clear lost hint */ tp->retransmit_skb_hint = NULL; } - /* SACK enhanced F-RTO detection. - * Set flag if and only if non-rexmitted - * segments below frto_highmark are - * SACKed (RFC4138; Appendix B). - * Clearing correct due to in-order walk - */ - if (after(end_seq, tp->frto_highmark)) { - flag &= ~FLAG_ONLY_ORIG_SACKED; - } else { - if (!(sacked & TCPCB_RETRANS)) - flag |= FLAG_ONLY_ORIG_SACKED; - } } TCP_SKB_CB(skb)->sacked |= TCPCB_SACKED_ACKED; @@ -1503,6 +1496,12 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ tp->retransmit_skb_hint = NULL; } } + + /* SACK enhanced FRTO (RFC4138, Appendix B): Clearing correct + * due to in-order walk + */ + if (after(end_seq, tp->frto_highmark)) + flag &= ~FLAG_ONLY_ORIG_SACKED; } if (tp->retrans_out && -- 2.20.1