Fix a bug with transmitter restart after receiving a 0 window. The
receiver was not sending an immediate ack with delayed acks turned on when the input buffer is drained, preventing the transmitter from restarting immediately. Propogate the TCP_NODELAY option to accept()ed sockets. (Helps tbench and is a good idea anyway). Some cleanup. Identify additonal issues in comments. MFC after: 1 day
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parent
fce6fbfa4d
commit
262c1c1a4e
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=87193
@ -152,10 +152,15 @@ do { \
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#endif
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/*
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* Indicate whether this ack should be delayed.
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* Indicate whether this ack should be delayed. We can delay the ack if
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* - delayed acks are enabled and
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* - there is no delayed ack timer in progress and
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* - our last ack wasn't a 0-sized window. We never want to delay
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* the ack that opens up a 0-sized window.
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*/
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#define DELAY_ACK(tp) \
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(tcp_delack_enabled && !callout_pending(tp->tt_delack))
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(tcp_delack_enabled && !callout_pending(tp->tt_delack) && \
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(tp->t_flags & TF_RXWIN0SENT) == 0)
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static int
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tcp_reass(tp, th, tlenp, m)
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@ -118,7 +118,9 @@ tcp_output(tp)
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u_char opt[TCP_MAXOLEN];
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unsigned ipoptlen, optlen, hdrlen;
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int idle, sendalot;
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#if 0
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int maxburst = TCP_MAXBURST;
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#endif
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struct rmxp_tao *taop;
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struct rmxp_tao tao_noncached;
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#ifdef INET6
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@ -277,28 +279,38 @@ tcp_output(tp)
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win = sbspace(&so->so_rcv);
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/*
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* Sender silly window avoidance. If connection is idle
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* and can send all data, a maximum segment,
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* at least a maximum default-size segment do it,
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* or are forced, do it; otherwise don't bother.
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* If peer's buffer is tiny, then send
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* when window is at least half open.
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* If retransmitting (possibly after persist timer forced us
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* to send into a small window), then must resend.
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* Sender silly window avoidance. We transmit under the following
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* conditions when len is non-zero:
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*
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* - We have a full segment
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* - This is the last buffer in a write()/send() and we are
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* either idle or running NODELAY
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* - we've timed out (e.g. persist timer)
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* - we have more then 1/2 the maximum send window's worth of
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* data (receiver may be limited the window size)
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* - we need to retransmit
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*/
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if (len) {
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if (len == tp->t_maxseg)
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goto send;
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if (!(tp->t_flags & TF_MORETOCOME) &&
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(idle || tp->t_flags & TF_NODELAY) &&
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(tp->t_flags & TF_NOPUSH) == 0 &&
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len + off >= so->so_snd.sb_cc)
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/*
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* NOTE! on localhost connections an 'ack' from the remote
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* end may occur synchronously with the output and cause
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* us to flush a buffer queued with moretocome. XXX
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*
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* note: the len + off check is almost certainly unnecessary.
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*/
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if (!(tp->t_flags & TF_MORETOCOME) && /* normal case */
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(idle || (tp->t_flags & TF_NODELAY)) &&
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len + off >= so->so_snd.sb_cc &&
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(tp->t_flags & TF_NOPUSH) == 0) {
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goto send;
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if (tp->t_force)
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}
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if (tp->t_force) /* typ. timeout case */
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goto send;
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if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0)
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goto send;
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if (SEQ_LT(tp->snd_nxt, tp->snd_max))
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if (SEQ_LT(tp->snd_nxt, tp->snd_max)) /* retransmit case */
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goto send;
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}
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@ -697,6 +709,20 @@ tcp_output(tp)
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if (win > (long)TCP_MAXWIN << tp->rcv_scale)
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win = (long)TCP_MAXWIN << tp->rcv_scale;
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th->th_win = htons((u_short) (win>>tp->rcv_scale));
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/*
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* Adjust the RXWIN0SENT flag - indicate that we have advertised
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* a 0 window. This may cause the remote transmitter to stall. This
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* flag tells soreceive() to disable delayed acknowledgements when
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* draining the buffer. This can occur if the receiver is attempting
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* to read more data then can be buffered prior to transmitting on
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* the connection.
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*/
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if (win == 0)
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tp->t_flags |= TF_RXWIN0SENT;
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else
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tp->t_flags &= ~TF_RXWIN0SENT;
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if (SEQ_GT(tp->snd_up, tp->snd_nxt)) {
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th->th_urp = htons((u_short)(tp->snd_up - tp->snd_nxt));
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th->th_flags |= TH_URG;
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@ -152,10 +152,15 @@ do { \
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#endif
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/*
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* Indicate whether this ack should be delayed.
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* Indicate whether this ack should be delayed. We can delay the ack if
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* - delayed acks are enabled and
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* - there is no delayed ack timer in progress and
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* - our last ack wasn't a 0-sized window. We never want to delay
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* the ack that opens up a 0-sized window.
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*/
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#define DELAY_ACK(tp) \
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(tcp_delack_enabled && !callout_pending(tp->tt_delack))
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(tcp_delack_enabled && !callout_pending(tp->tt_delack) && \
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(tp->t_flags & TF_RXWIN0SENT) == 0)
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static int
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tcp_reass(tp, th, tlenp, m)
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@ -657,7 +657,7 @@ syncache_socket(sc, lso)
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tp->rcv_wnd = sc->sc_wnd;
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tp->rcv_adv += tp->rcv_wnd;
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tp->t_flags = sc->sc_tp->t_flags & TF_NOPUSH;
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tp->t_flags = sc->sc_tp->t_flags & (TF_NOPUSH|TF_NODELAY);
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if (sc->sc_flags & SCF_NOOPT)
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tp->t_flags |= TF_NOOPT;
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if (sc->sc_flags & SCF_WINSCALE) {
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@ -101,6 +101,7 @@ struct tcpcb {
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#define TF_MORETOCOME 0x10000 /* More data to be appended to sock */
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#define TF_LQ_OVERFLOW 0x20000 /* listen queue overflow */
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#define TF_LASTIDLE 0x40000 /* connection was previously idle */
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#define TF_RXWIN0SENT 0x80000 /* sent a receiver win 0 in response */
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int t_force; /* 1 if forcing out a byte */
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tcp_seq snd_una; /* send unacknowledged */
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