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Adjust r239672 from rrs and r258821 from eadler.

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By definition, the very first FIN is not a duplicate. Process it normally
and don't feed it to congestion control as though it were a dupe.  Don't
prevent CC from seeing later dupe acks while in a half close state.
This commit is contained in:
peter 2014-01-28 21:13:15 +00:00
parent a638f0acf5
commit e7e77ae2a8
1 changed files with 13 additions and 32 deletions
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45
sys/netinet/tcp_input.c
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@ -2429,8 +2429,19 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
hhook_run_tcp_est_in(tp, th, &to);
if (SEQ_LEQ(th->th_ack, tp->snd_una)) {
if (tlen == 0 && tiwin == tp->snd_wnd &&
!(thflags & TH_FIN)) {
if (tlen == 0 && tiwin == tp->snd_wnd) {
/*
* If this is the first time we've seen a
* FIN from the remote, this is not a
* duplicate and it needs to be processed
* normally. This happens during a
* simultaneous close.
*/
if ((thflags & TH_FIN) &&
(TCPS_HAVERCVDFIN(tp->t_state) == 0)) {
tp->t_dupacks = 0;
break;
}
TCPSTAT_INC(tcps_rcvdupack);
/*
* If we have outstanding data (other than
@ -2485,16 +2496,6 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
}
} else
tp->snd_cwnd += tp->t_maxseg;
if ((thflags & TH_FIN) &&
(TCPS_HAVERCVDFIN(tp->t_state) == 0)) {
/*
* If its a fin we need to process
* it to avoid a race where both
* sides enter FIN-WAIT and send FIN|ACK
* at the same time.
*/
break;
}
(void) tcp_output(tp);
goto drop;
} else if (tp->t_dupacks == tcprexmtthresh) {
@ -2534,16 +2535,6 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
}
tp->snd_nxt = th->th_ack;
tp->snd_cwnd = tp->t_maxseg;
if ((thflags & TH_FIN) &&
(TCPS_HAVERCVDFIN(tp->t_state) == 0)) {
/*
* If its a fin we need to process
* it to avoid a race where both
* sides enter FIN-WAIT and send FIN|ACK
* at the same time.
*/
break;
}
(void) tcp_output(tp);
KASSERT(tp->snd_limited <= 2,
("%s: tp->snd_limited too big",
@ -2571,16 +2562,6 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
(tp->snd_nxt - tp->snd_una) +
(tp->t_dupacks - tp->snd_limited) *
tp->t_maxseg;
if ((thflags & TH_FIN) &&
(TCPS_HAVERCVDFIN(tp->t_state) == 0)) {
/*
* If its a fin we need to process
* it to avoid a race where both
* sides enter FIN-WAIT and send FIN|ACK
* at the same time.
*/
break;
}
/*
* Only call tcp_output when there
* is new data available to be sent.