The Design and Implementation of the FreeBSD Operating System, Second Edition
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sys/netinet/sctp_cc_functions.c

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    1 /*-
    2  * Copyright (c) 2001-2007, by Cisco Systems, Inc. All rights reserved.
    3  *
    4  * Redistribution and use in source and binary forms, with or without
    5  * modification, are permitted provided that the following conditions are met:
    6  *
    7  * a) Redistributions of source code must retain the above copyright notice,
    8  *   this list of conditions and the following disclaimer.
    9  *
   10  * b) Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in
   12  *   the documentation and/or other materials provided with the distribution.
   13  *
   14  * c) Neither the name of Cisco Systems, Inc. nor the names of its
   15  *    contributors may be used to endorse or promote products derived
   16  *    from this software without specific prior written permission.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
   20  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   21  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   22  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   24  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   25  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   26  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
   28  * THE POSSIBILITY OF SUCH DAMAGE.
   29  */
   30 
   31 #include <netinet/sctp_os.h>
   32 #include <netinet/sctp_var.h>
   33 #include <netinet/sctp_sysctl.h>
   34 #include <netinet/sctp_pcb.h>
   35 #include <netinet/sctp_header.h>
   36 #include <netinet/sctputil.h>
   37 #include <netinet/sctp_output.h>
   38 #include <netinet/sctp_input.h>
   39 #include <netinet/sctp_indata.h>
   40 #include <netinet/sctp_uio.h>
   41 #include <netinet/sctp_timer.h>
   42 #include <netinet/sctp_auth.h>
   43 #include <netinet/sctp_asconf.h>
   44 #include <netinet/sctp_cc_functions.h>
   45 #include <sys/cdefs.h>
   46 __FBSDID("$FreeBSD: releng/8.2/sys/netinet/sctp_cc_functions.c 214484 2010-10-28 19:12:05Z tuexen $");
   47 
   48 void
   49 sctp_set_initial_cc_param(struct sctp_tcb *stcb, struct sctp_nets *net)
   50 {
   51         struct sctp_association *assoc;
   52         uint32_t cwnd_in_mtu;
   53 
   54         assoc = &stcb->asoc;
   55         /*
   56          * We take the minimum of the burst limit and the initial congestion
   57          * window. The initial congestion window is at least two times the
   58          * MTU.
   59          */
   60         cwnd_in_mtu = SCTP_BASE_SYSCTL(sctp_initial_cwnd);
   61         if ((assoc->max_burst > 0) && (cwnd_in_mtu > assoc->max_burst))
   62                 cwnd_in_mtu = assoc->max_burst;
   63         net->cwnd = (net->mtu - sizeof(struct sctphdr)) * cwnd_in_mtu;
   64         net->ssthresh = assoc->peers_rwnd;
   65 
   66         if (SCTP_BASE_SYSCTL(sctp_logging_level) &
   67             (SCTP_CWND_MONITOR_ENABLE | SCTP_CWND_LOGGING_ENABLE)) {
   68                 sctp_log_cwnd(stcb, net, 0, SCTP_CWND_INITIALIZATION);
   69         }
   70 }
   71 
   72 void
   73 sctp_cwnd_update_after_fr(struct sctp_tcb *stcb,
   74     struct sctp_association *asoc)
   75 {
   76         struct sctp_nets *net;
   77 
   78         /*-
   79          * CMT fast recovery code. Need to debug. ((sctp_cmt_on_off == 1) &&
   80          * (net->fast_retran_loss_recovery == 0)))
   81          */
   82         TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
   83                 if ((asoc->fast_retran_loss_recovery == 0) ||
   84                     (asoc->sctp_cmt_on_off == 1)) {
   85                         /* out of a RFC2582 Fast recovery window? */
   86                         if (net->net_ack > 0) {
   87                                 /*
   88                                  * per section 7.2.3, are there any
   89                                  * destinations that had a fast retransmit
   90                                  * to them. If so what we need to do is
   91                                  * adjust ssthresh and cwnd.
   92                                  */
   93                                 struct sctp_tmit_chunk *lchk;
   94                                 int old_cwnd = net->cwnd;
   95 
   96                                 net->ssthresh = net->cwnd / 2;
   97                                 if (net->ssthresh < (net->mtu * 2)) {
   98                                         net->ssthresh = 2 * net->mtu;
   99                                 }
  100                                 net->cwnd = net->ssthresh;
  101                                 if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  102                                         sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd),
  103                                             SCTP_CWND_LOG_FROM_FR);
  104                                 }
  105                                 lchk = TAILQ_FIRST(&asoc->send_queue);
  106 
  107                                 net->partial_bytes_acked = 0;
  108                                 /* Turn on fast recovery window */
  109                                 asoc->fast_retran_loss_recovery = 1;
  110                                 if (lchk == NULL) {
  111                                         /* Mark end of the window */
  112                                         asoc->fast_recovery_tsn = asoc->sending_seq - 1;
  113                                 } else {
  114                                         asoc->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
  115                                 }
  116 
  117                                 /*
  118                                  * CMT fast recovery -- per destination
  119                                  * recovery variable.
  120                                  */
  121                                 net->fast_retran_loss_recovery = 1;
  122 
  123                                 if (lchk == NULL) {
  124                                         /* Mark end of the window */
  125                                         net->fast_recovery_tsn = asoc->sending_seq - 1;
  126                                 } else {
  127                                         net->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
  128                                 }
  129 
  130                                 /*
  131                                  * Disable Nonce Sum Checking and store the
  132                                  * resync tsn
  133                                  */
  134                                 asoc->nonce_sum_check = 0;
  135                                 asoc->nonce_resync_tsn = asoc->fast_recovery_tsn + 1;
  136 
  137                                 sctp_timer_stop(SCTP_TIMER_TYPE_SEND,
  138                                     stcb->sctp_ep, stcb, net, SCTP_FROM_SCTP_INDATA + SCTP_LOC_32);
  139                                 sctp_timer_start(SCTP_TIMER_TYPE_SEND,
  140                                     stcb->sctp_ep, stcb, net);
  141                         }
  142                 } else if (net->net_ack > 0) {
  143                         /*
  144                          * Mark a peg that we WOULD have done a cwnd
  145                          * reduction but RFC2582 prevented this action.
  146                          */
  147                         SCTP_STAT_INCR(sctps_fastretransinrtt);
  148                 }
  149         }
  150 }
  151 
  152 void
  153 sctp_cwnd_update_after_sack(struct sctp_tcb *stcb,
  154     struct sctp_association *asoc,
  155     int accum_moved, int reneged_all, int will_exit)
  156 {
  157         struct sctp_nets *net;
  158 
  159         /******************************/
  160         /* update cwnd and Early FR   */
  161         /******************************/
  162         TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
  163 
  164 #ifdef JANA_CMT_FAST_RECOVERY
  165                 /*
  166                  * CMT fast recovery code. Need to debug.
  167                  */
  168                 if (net->fast_retran_loss_recovery && net->new_pseudo_cumack) {
  169                         if (compare_with_wrap(asoc->last_acked_seq,
  170                             net->fast_recovery_tsn, MAX_TSN) ||
  171                             (asoc->last_acked_seq == net->fast_recovery_tsn) ||
  172                             compare_with_wrap(net->pseudo_cumack, net->fast_recovery_tsn, MAX_TSN) ||
  173                             (net->pseudo_cumack == net->fast_recovery_tsn)) {
  174                                 net->will_exit_fast_recovery = 1;
  175                         }
  176                 }
  177 #endif
  178                 if (SCTP_BASE_SYSCTL(sctp_early_fr)) {
  179                         /*
  180                          * So, first of all do we need to have a Early FR
  181                          * timer running?
  182                          */
  183                         if ((!TAILQ_EMPTY(&asoc->sent_queue) &&
  184                             (net->ref_count > 1) &&
  185                             (net->flight_size < net->cwnd)) ||
  186                             (reneged_all)) {
  187                                 /*
  188                                  * yes, so in this case stop it if its
  189                                  * running, and then restart it. Reneging
  190                                  * all is a special case where we want to
  191                                  * run the Early FR timer and then force the
  192                                  * last few unacked to be sent, causing us
  193                                  * to illicit a sack with gaps to force out
  194                                  * the others.
  195                                  */
  196                                 if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
  197                                         SCTP_STAT_INCR(sctps_earlyfrstpidsck2);
  198                                         sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
  199                                             SCTP_FROM_SCTP_INDATA + SCTP_LOC_20);
  200                                 }
  201                                 SCTP_STAT_INCR(sctps_earlyfrstrid);
  202                                 sctp_timer_start(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net);
  203                         } else {
  204                                 /* No, stop it if its running */
  205                                 if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
  206                                         SCTP_STAT_INCR(sctps_earlyfrstpidsck3);
  207                                         sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
  208                                             SCTP_FROM_SCTP_INDATA + SCTP_LOC_21);
  209                                 }
  210                         }
  211                 }
  212                 /* if nothing was acked on this destination skip it */
  213                 if (net->net_ack == 0) {
  214                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
  215                                 sctp_log_cwnd(stcb, net, 0, SCTP_CWND_LOG_FROM_SACK);
  216                         }
  217                         continue;
  218                 }
  219                 if (net->net_ack2 > 0) {
  220                         /*
  221                          * Karn's rule applies to clearing error count, this
  222                          * is optional.
  223                          */
  224                         net->error_count = 0;
  225                         if ((net->dest_state & SCTP_ADDR_NOT_REACHABLE) ==
  226                             SCTP_ADDR_NOT_REACHABLE) {
  227                                 /* addr came good */
  228                                 net->dest_state &= ~SCTP_ADDR_NOT_REACHABLE;
  229                                 net->dest_state |= SCTP_ADDR_REACHABLE;
  230                                 sctp_ulp_notify(SCTP_NOTIFY_INTERFACE_UP, stcb,
  231                                     SCTP_RECEIVED_SACK, (void *)net, SCTP_SO_NOT_LOCKED);
  232                                 /* now was it the primary? if so restore */
  233                                 if (net->dest_state & SCTP_ADDR_WAS_PRIMARY) {
  234                                         (void)sctp_set_primary_addr(stcb, (struct sockaddr *)NULL, net);
  235                                 }
  236                         }
  237                         /*
  238                          * JRS 5/14/07 - If CMT PF is on and the destination
  239                          * is in PF state, set the destination to active
  240                          * state and set the cwnd to one or two MTU's based
  241                          * on whether PF1 or PF2 is being used.
  242                          * 
  243                          * Should we stop any running T3 timer here?
  244                          */
  245                         if ((asoc->sctp_cmt_on_off == 1) &&
  246                             (asoc->sctp_cmt_pf > 0) &&
  247                             ((net->dest_state & SCTP_ADDR_PF) == SCTP_ADDR_PF)) {
  248                                 net->dest_state &= ~SCTP_ADDR_PF;
  249                                 net->cwnd = net->mtu * asoc->sctp_cmt_pf;
  250                                 SCTPDBG(SCTP_DEBUG_INDATA1, "Destination %p moved from PF to reachable with cwnd %d.\n",
  251                                     net, net->cwnd);
  252                                 /*
  253                                  * Since the cwnd value is explicitly set,
  254                                  * skip the code that updates the cwnd
  255                                  * value.
  256                                  */
  257                                 goto skip_cwnd_update;
  258                         }
  259                 }
  260 #ifdef JANA_CMT_FAST_RECOVERY
  261                 /*
  262                  * CMT fast recovery code
  263                  */
  264                 /*
  265                  * if (sctp_cmt_on_off == 1 &&
  266                  * net->fast_retran_loss_recovery &&
  267                  * net->will_exit_fast_recovery == 0) { @@@ Do something }
  268                  * else if (sctp_cmt_on_off == 0 &&
  269                  * asoc->fast_retran_loss_recovery && will_exit == 0) {
  270                  */
  271 #endif
  272 
  273                 if (asoc->fast_retran_loss_recovery &&
  274                     (will_exit == 0) &&
  275                     (asoc->sctp_cmt_on_off == 0)) {
  276                         /*
  277                          * If we are in loss recovery we skip any cwnd
  278                          * update
  279                          */
  280                         goto skip_cwnd_update;
  281                 }
  282                 /*
  283                  * CMT: CUC algorithm. Update cwnd if pseudo-cumack has
  284                  * moved.
  285                  */
  286                 if (accum_moved ||
  287                     ((asoc->sctp_cmt_on_off == 1) && net->new_pseudo_cumack)) {
  288                         /* If the cumulative ack moved we can proceed */
  289                         if (net->cwnd <= net->ssthresh) {
  290                                 /* We are in slow start */
  291                                 if (net->flight_size + net->net_ack >= net->cwnd) {
  292                                         if (net->net_ack > (net->mtu * SCTP_BASE_SYSCTL(sctp_L2_abc_variable))) {
  293                                                 net->cwnd += (net->mtu * SCTP_BASE_SYSCTL(sctp_L2_abc_variable));
  294                                                 if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  295                                                         sctp_log_cwnd(stcb, net, net->mtu,
  296                                                             SCTP_CWND_LOG_FROM_SS);
  297                                                 }
  298                                         } else {
  299                                                 net->cwnd += net->net_ack;
  300                                                 if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  301                                                         sctp_log_cwnd(stcb, net, net->net_ack,
  302                                                             SCTP_CWND_LOG_FROM_SS);
  303                                                 }
  304                                         }
  305                                 } else {
  306                                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
  307                                                 sctp_log_cwnd(stcb, net, net->net_ack,
  308                                                     SCTP_CWND_LOG_NOADV_SS);
  309                                         }
  310                                 }
  311                         } else {
  312                                 /* We are in congestion avoidance */
  313                                 /*
  314                                  * Add to pba
  315                                  */
  316                                 net->partial_bytes_acked += net->net_ack;
  317 
  318                                 if ((net->flight_size + net->net_ack >= net->cwnd) &&
  319                                     (net->partial_bytes_acked >= net->cwnd)) {
  320                                         net->partial_bytes_acked -= net->cwnd;
  321                                         net->cwnd += net->mtu;
  322                                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  323                                                 sctp_log_cwnd(stcb, net, net->mtu,
  324                                                     SCTP_CWND_LOG_FROM_CA);
  325                                         }
  326                                 } else {
  327                                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
  328                                                 sctp_log_cwnd(stcb, net, net->net_ack,
  329                                                     SCTP_CWND_LOG_NOADV_CA);
  330                                         }
  331                                 }
  332                         }
  333                 } else {
  334                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
  335                                 sctp_log_cwnd(stcb, net, net->mtu,
  336                                     SCTP_CWND_LOG_NO_CUMACK);
  337                         }
  338                 }
  339 skip_cwnd_update:
  340                 /*
  341                  * NOW, according to Karn's rule do we need to restore the
  342                  * RTO timer back? Check our net_ack2. If not set then we
  343                  * have a ambiguity.. i.e. all data ack'd was sent to more
  344                  * than one place.
  345                  */
  346                 if (net->net_ack2) {
  347                         /* restore any doubled timers */
  348                         net->RTO = ((net->lastsa >> 2) + net->lastsv) >> 1;
  349                         if (net->RTO < stcb->asoc.minrto) {
  350                                 net->RTO = stcb->asoc.minrto;
  351                         }
  352                         if (net->RTO > stcb->asoc.maxrto) {
  353                                 net->RTO = stcb->asoc.maxrto;
  354                         }
  355                 }
  356         }
  357 }
  358 
  359 void
  360 sctp_cwnd_update_after_timeout(struct sctp_tcb *stcb, struct sctp_nets *net)
  361 {
  362         int old_cwnd = net->cwnd;
  363 
  364         net->ssthresh = max(net->cwnd / 2, 4 * net->mtu);
  365         net->cwnd = net->mtu;
  366         net->partial_bytes_acked = 0;
  367 
  368         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  369                 sctp_log_cwnd(stcb, net, net->cwnd - old_cwnd, SCTP_CWND_LOG_FROM_RTX);
  370         }
  371 }
  372 
  373 void
  374 sctp_cwnd_update_after_ecn_echo(struct sctp_tcb *stcb, struct sctp_nets *net)
  375 {
  376         int old_cwnd = net->cwnd;
  377 
  378         SCTP_STAT_INCR(sctps_ecnereducedcwnd);
  379         net->ssthresh = net->cwnd / 2;
  380         if (net->ssthresh < net->mtu) {
  381                 net->ssthresh = net->mtu;
  382                 /* here back off the timer as well, to slow us down */
  383                 net->RTO <<= 1;
  384         }
  385         net->cwnd = net->ssthresh;
  386         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  387                 sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd), SCTP_CWND_LOG_FROM_SAT);
  388         }
  389 }
  390 
  391 void
  392 sctp_cwnd_update_after_packet_dropped(struct sctp_tcb *stcb,
  393     struct sctp_nets *net, struct sctp_pktdrop_chunk *cp,
  394     uint32_t * bottle_bw, uint32_t * on_queue)
  395 {
  396         uint32_t bw_avail;
  397         int rtt, incr;
  398         int old_cwnd = net->cwnd;
  399 
  400         /* need real RTT for this calc */
  401         rtt = ((net->lastsa >> 2) + net->lastsv) >> 1;
  402         /* get bottle neck bw */
  403         *bottle_bw = ntohl(cp->bottle_bw);
  404         /* and whats on queue */
  405         *on_queue = ntohl(cp->current_onq);
  406         /*
  407          * adjust the on-queue if our flight is more it could be that the
  408          * router has not yet gotten data "in-flight" to it
  409          */
  410         if (*on_queue < net->flight_size)
  411                 *on_queue = net->flight_size;
  412         /* calculate the available space */
  413         bw_avail = (*bottle_bw * rtt) / 1000;
  414         if (bw_avail > *bottle_bw) {
  415                 /*
  416                  * Cap the growth to no more than the bottle neck. This can
  417                  * happen as RTT slides up due to queues. It also means if
  418                  * you have more than a 1 second RTT with a empty queue you
  419                  * will be limited to the bottle_bw per second no matter if
  420                  * other points have 1/2 the RTT and you could get more
  421                  * out...
  422                  */
  423                 bw_avail = *bottle_bw;
  424         }
  425         if (*on_queue > bw_avail) {
  426                 /*
  427                  * No room for anything else don't allow anything else to be
  428                  * "added to the fire".
  429                  */
  430                 int seg_inflight, seg_onqueue, my_portion;
  431 
  432                 net->partial_bytes_acked = 0;
  433 
  434                 /* how much are we over queue size? */
  435                 incr = *on_queue - bw_avail;
  436                 if (stcb->asoc.seen_a_sack_this_pkt) {
  437                         /*
  438                          * undo any cwnd adjustment that the sack might have
  439                          * made
  440                          */
  441                         net->cwnd = net->prev_cwnd;
  442                 }
  443                 /* Now how much of that is mine? */
  444                 seg_inflight = net->flight_size / net->mtu;
  445                 seg_onqueue = *on_queue / net->mtu;
  446                 my_portion = (incr * seg_inflight) / seg_onqueue;
  447 
  448                 /* Have I made an adjustment already */
  449                 if (net->cwnd > net->flight_size) {
  450                         /*
  451                          * for this flight I made an adjustment we need to
  452                          * decrease the portion by a share our previous
  453                          * adjustment.
  454                          */
  455                         int diff_adj;
  456 
  457                         diff_adj = net->cwnd - net->flight_size;
  458                         if (diff_adj > my_portion)
  459                                 my_portion = 0;
  460                         else
  461                                 my_portion -= diff_adj;
  462                 }
  463                 /*
  464                  * back down to the previous cwnd (assume we have had a sack
  465                  * before this packet). minus what ever portion of the
  466                  * overage is my fault.
  467                  */
  468                 net->cwnd -= my_portion;
  469 
  470                 /* we will NOT back down more than 1 MTU */
  471                 if (net->cwnd <= net->mtu) {
  472                         net->cwnd = net->mtu;
  473                 }
  474                 /* force into CA */
  475                 net->ssthresh = net->cwnd - 1;
  476         } else {
  477                 /*
  478                  * Take 1/4 of the space left or max burst up .. whichever
  479                  * is less.
  480                  */
  481                 incr = min((bw_avail - *on_queue) >> 2,
  482                     stcb->asoc.max_burst * net->mtu);
  483                 net->cwnd += incr;
  484         }
  485         if (net->cwnd > bw_avail) {
  486                 /* We can't exceed the pipe size */
  487                 net->cwnd = bw_avail;
  488         }
  489         if (net->cwnd < net->mtu) {
  490                 /* We always have 1 MTU */
  491                 net->cwnd = net->mtu;
  492         }
  493         if (net->cwnd - old_cwnd != 0) {
  494                 /* log only changes */
  495                 if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  496                         sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd),
  497                             SCTP_CWND_LOG_FROM_SAT);
  498                 }
  499         }
  500 }
  501 
  502 void
  503 sctp_cwnd_update_after_output(struct sctp_tcb *stcb,
  504     struct sctp_nets *net, int burst_limit)
  505 {
  506         int old_cwnd = net->cwnd;
  507 
  508         if (net->ssthresh < net->cwnd)
  509                 net->ssthresh = net->cwnd;
  510         net->cwnd = (net->flight_size + (burst_limit * net->mtu));
  511 
  512         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  513                 sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd), SCTP_CWND_LOG_FROM_BRST);
  514         }
  515 }
  516 
  517 void
  518 sctp_cwnd_update_after_fr_timer(struct sctp_inpcb *inp,
  519     struct sctp_tcb *stcb, struct sctp_nets *net)
  520 {
  521         int old_cwnd = net->cwnd;
  522 
  523         sctp_chunk_output(inp, stcb, SCTP_OUTPUT_FROM_EARLY_FR_TMR, SCTP_SO_NOT_LOCKED);
  524         /*
  525          * make a small adjustment to cwnd and force to CA.
  526          */
  527         if (net->cwnd > net->mtu)
  528                 /* drop down one MTU after sending */
  529                 net->cwnd -= net->mtu;
  530         if (net->cwnd < net->ssthresh)
  531                 /* still in SS move to CA */
  532                 net->ssthresh = net->cwnd - 1;
  533         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  534                 sctp_log_cwnd(stcb, net, (old_cwnd - net->cwnd), SCTP_CWND_LOG_FROM_FR);
  535         }
  536 }
  537 
  538 struct sctp_hs_raise_drop {
  539         int32_t cwnd;
  540         int32_t increase;
  541         int32_t drop_percent;
  542 };
  543 
  544 #define SCTP_HS_TABLE_SIZE 73
  545 
  546 struct sctp_hs_raise_drop sctp_cwnd_adjust[SCTP_HS_TABLE_SIZE] = {
  547         {38, 1, 50},            /* 0   */
  548         {118, 2, 44},           /* 1   */
  549         {221, 3, 41},           /* 2   */
  550         {347, 4, 38},           /* 3   */
  551         {495, 5, 37},           /* 4   */
  552         {663, 6, 35},           /* 5   */
  553         {851, 7, 34},           /* 6   */
  554         {1058, 8, 33},          /* 7   */
  555         {1284, 9, 32},          /* 8   */
  556         {1529, 10, 31},         /* 9   */
  557         {1793, 11, 30},         /* 10  */
  558         {2076, 12, 29},         /* 11  */
  559         {2378, 13, 28},         /* 12  */
  560         {2699, 14, 28},         /* 13  */
  561         {3039, 15, 27},         /* 14  */
  562         {3399, 16, 27},         /* 15  */
  563         {3778, 17, 26},         /* 16  */
  564         {4177, 18, 26},         /* 17  */
  565         {4596, 19, 25},         /* 18  */
  566         {5036, 20, 25},         /* 19  */
  567         {5497, 21, 24},         /* 20  */
  568         {5979, 22, 24},         /* 21  */
  569         {6483, 23, 23},         /* 22  */
  570         {7009, 24, 23},         /* 23  */
  571         {7558, 25, 22},         /* 24  */
  572         {8130, 26, 22},         /* 25  */
  573         {8726, 27, 22},         /* 26  */
  574         {9346, 28, 21},         /* 27  */
  575         {9991, 29, 21},         /* 28  */
  576         {10661, 30, 21},        /* 29  */
  577         {11358, 31, 20},        /* 30  */
  578         {12082, 32, 20},        /* 31  */
  579         {12834, 33, 20},        /* 32  */
  580         {13614, 34, 19},        /* 33  */
  581         {14424, 35, 19},        /* 34  */
  582         {15265, 36, 19},        /* 35  */
  583         {16137, 37, 19},        /* 36  */
  584         {17042, 38, 18},        /* 37  */
  585         {17981, 39, 18},        /* 38  */
  586         {18955, 40, 18},        /* 39  */
  587         {19965, 41, 17},        /* 40  */
  588         {21013, 42, 17},        /* 41  */
  589         {22101, 43, 17},        /* 42  */
  590         {23230, 44, 17},        /* 43  */
  591         {24402, 45, 16},        /* 44  */
  592         {25618, 46, 16},        /* 45  */
  593         {26881, 47, 16},        /* 46  */
  594         {28193, 48, 16},        /* 47  */
  595         {29557, 49, 15},        /* 48  */
  596         {30975, 50, 15},        /* 49  */
  597         {32450, 51, 15},        /* 50  */
  598         {33986, 52, 15},        /* 51  */
  599         {35586, 53, 14},        /* 52  */
  600         {37253, 54, 14},        /* 53  */
  601         {38992, 55, 14},        /* 54  */
  602         {40808, 56, 14},        /* 55  */
  603         {42707, 57, 13},        /* 56  */
  604         {44694, 58, 13},        /* 57  */
  605         {46776, 59, 13},        /* 58  */
  606         {48961, 60, 13},        /* 59  */
  607         {51258, 61, 13},        /* 60  */
  608         {53677, 62, 12},        /* 61  */
  609         {56230, 63, 12},        /* 62  */
  610         {58932, 64, 12},        /* 63  */
  611         {61799, 65, 12},        /* 64  */
  612         {64851, 66, 11},        /* 65  */
  613         {68113, 67, 11},        /* 66  */
  614         {71617, 68, 11},        /* 67  */
  615         {75401, 69, 10},        /* 68  */
  616         {79517, 70, 10},        /* 69  */
  617         {84035, 71, 10},        /* 70  */
  618         {89053, 72, 10},        /* 71  */
  619         {94717, 73, 9}          /* 72  */
  620 };
  621 
  622 static void
  623 sctp_hs_cwnd_increase(struct sctp_tcb *stcb, struct sctp_nets *net)
  624 {
  625         int cur_val, i, indx, incr;
  626 
  627         cur_val = net->cwnd >> 10;
  628         indx = SCTP_HS_TABLE_SIZE - 1;
  629 #ifdef SCTP_DEBUG
  630         printf("HS CC CAlled.\n");
  631 #endif
  632         if (cur_val < sctp_cwnd_adjust[0].cwnd) {
  633                 /* normal mode */
  634                 if (net->net_ack > net->mtu) {
  635                         net->cwnd += net->mtu;
  636                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  637                                 sctp_log_cwnd(stcb, net, net->mtu, SCTP_CWND_LOG_FROM_SS);
  638                         }
  639                 } else {
  640                         net->cwnd += net->net_ack;
  641                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  642                                 sctp_log_cwnd(stcb, net, net->net_ack, SCTP_CWND_LOG_FROM_SS);
  643                         }
  644                 }
  645         } else {
  646                 for (i = net->last_hs_used; i < SCTP_HS_TABLE_SIZE; i++) {
  647                         if (cur_val < sctp_cwnd_adjust[i].cwnd) {
  648                                 indx = i;
  649                                 break;
  650                         }
  651                 }
  652                 net->last_hs_used = indx;
  653                 incr = ((sctp_cwnd_adjust[indx].increase) << 10);
  654                 net->cwnd += incr;
  655                 if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  656                         sctp_log_cwnd(stcb, net, incr, SCTP_CWND_LOG_FROM_SS);
  657                 }
  658         }
  659 }
  660 
  661 static void
  662 sctp_hs_cwnd_decrease(struct sctp_tcb *stcb, struct sctp_nets *net)
  663 {
  664         int cur_val, i, indx;
  665         int old_cwnd = net->cwnd;
  666 
  667         cur_val = net->cwnd >> 10;
  668         if (cur_val < sctp_cwnd_adjust[0].cwnd) {
  669                 /* normal mode */
  670                 net->ssthresh = net->cwnd / 2;
  671                 if (net->ssthresh < (net->mtu * 2)) {
  672                         net->ssthresh = 2 * net->mtu;
  673                 }
  674                 net->cwnd = net->ssthresh;
  675         } else {
  676                 /* drop by the proper amount */
  677                 net->ssthresh = net->cwnd - (int)((net->cwnd / 100) *
  678                     sctp_cwnd_adjust[net->last_hs_used].drop_percent);
  679                 net->cwnd = net->ssthresh;
  680                 /* now where are we */
  681                 indx = net->last_hs_used;
  682                 cur_val = net->cwnd >> 10;
  683                 /* reset where we are in the table */
  684                 if (cur_val < sctp_cwnd_adjust[0].cwnd) {
  685                         /* feel out of hs */
  686                         net->last_hs_used = 0;
  687                 } else {
  688                         for (i = indx; i >= 1; i--) {
  689                                 if (cur_val > sctp_cwnd_adjust[i - 1].cwnd) {
  690                                         break;
  691                                 }
  692                         }
  693                         net->last_hs_used = indx;
  694                 }
  695         }
  696         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  697                 sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd), SCTP_CWND_LOG_FROM_FR);
  698         }
  699 }
  700 
  701 void
  702 sctp_hs_cwnd_update_after_fr(struct sctp_tcb *stcb,
  703     struct sctp_association *asoc)
  704 {
  705         struct sctp_nets *net;
  706 
  707         /*
  708          * CMT fast recovery code. Need to debug. ((sctp_cmt_on_off == 1) &&
  709          * (net->fast_retran_loss_recovery == 0)))
  710          */
  711         TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
  712                 if ((asoc->fast_retran_loss_recovery == 0) ||
  713                     (asoc->sctp_cmt_on_off == 1)) {
  714                         /* out of a RFC2582 Fast recovery window? */
  715                         if (net->net_ack > 0) {
  716                                 /*
  717                                  * per section 7.2.3, are there any
  718                                  * destinations that had a fast retransmit
  719                                  * to them. If so what we need to do is
  720                                  * adjust ssthresh and cwnd.
  721                                  */
  722                                 struct sctp_tmit_chunk *lchk;
  723 
  724                                 sctp_hs_cwnd_decrease(stcb, net);
  725 
  726                                 lchk = TAILQ_FIRST(&asoc->send_queue);
  727 
  728                                 net->partial_bytes_acked = 0;
  729                                 /* Turn on fast recovery window */
  730                                 asoc->fast_retran_loss_recovery = 1;
  731                                 if (lchk == NULL) {
  732                                         /* Mark end of the window */
  733                                         asoc->fast_recovery_tsn = asoc->sending_seq - 1;
  734                                 } else {
  735                                         asoc->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
  736                                 }
  737 
  738                                 /*
  739                                  * CMT fast recovery -- per destination
  740                                  * recovery variable.
  741                                  */
  742                                 net->fast_retran_loss_recovery = 1;
  743 
  744                                 if (lchk == NULL) {
  745                                         /* Mark end of the window */
  746                                         net->fast_recovery_tsn = asoc->sending_seq - 1;
  747                                 } else {
  748                                         net->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
  749                                 }
  750 
  751                                 /*
  752                                  * Disable Nonce Sum Checking and store the
  753                                  * resync tsn
  754                                  */
  755                                 asoc->nonce_sum_check = 0;
  756                                 asoc->nonce_resync_tsn = asoc->fast_recovery_tsn + 1;
  757 
  758                                 sctp_timer_stop(SCTP_TIMER_TYPE_SEND,
  759                                     stcb->sctp_ep, stcb, net, SCTP_FROM_SCTP_INDATA + SCTP_LOC_32);
  760                                 sctp_timer_start(SCTP_TIMER_TYPE_SEND,
  761                                     stcb->sctp_ep, stcb, net);
  762                         }
  763                 } else if (net->net_ack > 0) {
  764                         /*
  765                          * Mark a peg that we WOULD have done a cwnd
  766                          * reduction but RFC2582 prevented this action.
  767                          */
  768                         SCTP_STAT_INCR(sctps_fastretransinrtt);
  769                 }
  770         }
  771 }
  772 
  773 void
  774 sctp_hs_cwnd_update_after_sack(struct sctp_tcb *stcb,
  775     struct sctp_association *asoc,
  776     int accum_moved, int reneged_all, int will_exit)
  777 {
  778         struct sctp_nets *net;
  779 
  780         /******************************/
  781         /* update cwnd and Early FR   */
  782         /******************************/
  783         TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
  784 
  785 #ifdef JANA_CMT_FAST_RECOVERY
  786                 /*
  787                  * CMT fast recovery code. Need to debug.
  788                  */
  789                 if (net->fast_retran_loss_recovery && net->new_pseudo_cumack) {
  790                         if (compare_with_wrap(asoc->last_acked_seq,
  791                             net->fast_recovery_tsn, MAX_TSN) ||
  792                             (asoc->last_acked_seq == net->fast_recovery_tsn) ||
  793                             compare_with_wrap(net->pseudo_cumack, net->fast_recovery_tsn, MAX_TSN) ||
  794                             (net->pseudo_cumack == net->fast_recovery_tsn)) {
  795                                 net->will_exit_fast_recovery = 1;
  796                         }
  797                 }
  798 #endif
  799                 if (SCTP_BASE_SYSCTL(sctp_early_fr)) {
  800                         /*
  801                          * So, first of all do we need to have a Early FR
  802                          * timer running?
  803                          */
  804                         if ((!TAILQ_EMPTY(&asoc->sent_queue) &&
  805                             (net->ref_count > 1) &&
  806                             (net->flight_size < net->cwnd)) ||
  807                             (reneged_all)) {
  808                                 /*
  809                                  * yes, so in this case stop it if its
  810                                  * running, and then restart it. Reneging
  811                                  * all is a special case where we want to
  812                                  * run the Early FR timer and then force the
  813                                  * last few unacked to be sent, causing us
  814                                  * to illicit a sack with gaps to force out
  815                                  * the others.
  816                                  */
  817                                 if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
  818                                         SCTP_STAT_INCR(sctps_earlyfrstpidsck2);
  819                                         sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
  820                                             SCTP_FROM_SCTP_INDATA + SCTP_LOC_20);
  821                                 }
  822                                 SCTP_STAT_INCR(sctps_earlyfrstrid);
  823                                 sctp_timer_start(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net);
  824                         } else {
  825                                 /* No, stop it if its running */
  826                                 if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
  827                                         SCTP_STAT_INCR(sctps_earlyfrstpidsck3);
  828                                         sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
  829                                             SCTP_FROM_SCTP_INDATA + SCTP_LOC_21);
  830                                 }
  831                         }
  832                 }
  833                 /* if nothing was acked on this destination skip it */
  834                 if (net->net_ack == 0) {
  835                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
  836                                 sctp_log_cwnd(stcb, net, 0, SCTP_CWND_LOG_FROM_SACK);
  837                         }
  838                         continue;
  839                 }
  840                 if (net->net_ack2 > 0) {
  841                         /*
  842                          * Karn's rule applies to clearing error count, this
  843                          * is optional.
  844                          */
  845                         net->error_count = 0;
  846                         if ((net->dest_state & SCTP_ADDR_NOT_REACHABLE) ==
  847                             SCTP_ADDR_NOT_REACHABLE) {
  848                                 /* addr came good */
  849                                 net->dest_state &= ~SCTP_ADDR_NOT_REACHABLE;
  850                                 net->dest_state |= SCTP_ADDR_REACHABLE;
  851                                 sctp_ulp_notify(SCTP_NOTIFY_INTERFACE_UP, stcb,
  852                                     SCTP_RECEIVED_SACK, (void *)net, SCTP_SO_NOT_LOCKED);
  853                                 /* now was it the primary? if so restore */
  854                                 if (net->dest_state & SCTP_ADDR_WAS_PRIMARY) {
  855                                         (void)sctp_set_primary_addr(stcb, (struct sockaddr *)NULL, net);
  856                                 }
  857                         }
  858                         /*
  859                          * JRS 5/14/07 - If CMT PF is on and the destination
  860                          * is in PF state, set the destination to active
  861                          * state and set the cwnd to one or two MTU's based
  862                          * on whether PF1 or PF2 is being used.
  863                          * 
  864                          * Should we stop any running T3 timer here?
  865                          */
  866                         if ((asoc->sctp_cmt_on_off == 1) &&
  867                             (asoc->sctp_cmt_pf > 0) &&
  868                             ((net->dest_state & SCTP_ADDR_PF) == SCTP_ADDR_PF)) {
  869                                 net->dest_state &= ~SCTP_ADDR_PF;
  870                                 net->cwnd = net->mtu * asoc->sctp_cmt_pf;
  871                                 SCTPDBG(SCTP_DEBUG_INDATA1, "Destination %p moved from PF to reachable with cwnd %d.\n",
  872                                     net, net->cwnd);
  873                                 /*
  874                                  * Since the cwnd value is explicitly set,
  875                                  * skip the code that updates the cwnd
  876                                  * value.
  877                                  */
  878                                 goto skip_cwnd_update;
  879                         }
  880                 }
  881 #ifdef JANA_CMT_FAST_RECOVERY
  882                 /*
  883                  * CMT fast recovery code
  884                  */
  885                 /*
  886                  * if (sctp_cmt_on_off == 1 &&
  887                  * net->fast_retran_loss_recovery &&
  888                  * net->will_exit_fast_recovery == 0) { @@@ Do something }
  889                  * else if (sctp_cmt_on_off == 0 &&
  890                  * asoc->fast_retran_loss_recovery && will_exit == 0) {
  891                  */
  892 #endif
  893 
  894                 if (asoc->fast_retran_loss_recovery &&
  895                     (will_exit == 0) &&
  896                     (asoc->sctp_cmt_on_off == 0)) {
  897                         /*
  898                          * If we are in loss recovery we skip any cwnd
  899                          * update
  900                          */
  901                         goto skip_cwnd_update;
  902                 }
  903                 /*
  904                  * CMT: CUC algorithm. Update cwnd if pseudo-cumack has
  905                  * moved.
  906                  */
  907                 if (accum_moved ||
  908                     ((asoc->sctp_cmt_on_off == 1) && net->new_pseudo_cumack)) {
  909                         /* If the cumulative ack moved we can proceed */
  910                         if (net->cwnd <= net->ssthresh) {
  911                                 /* We are in slow start */
  912                                 if (net->flight_size + net->net_ack >= net->cwnd) {
  913 
  914                                         sctp_hs_cwnd_increase(stcb, net);
  915 
  916                                 } else {
  917                                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
  918                                                 sctp_log_cwnd(stcb, net, net->net_ack,
  919                                                     SCTP_CWND_LOG_NOADV_SS);
  920                                         }
  921                                 }
  922                         } else {
  923                                 /* We are in congestion avoidance */
  924                                 net->partial_bytes_acked += net->net_ack;
  925                                 if ((net->flight_size + net->net_ack >= net->cwnd) &&
  926                                     (net->partial_bytes_acked >= net->cwnd)) {
  927                                         net->partial_bytes_acked -= net->cwnd;
  928                                         net->cwnd += net->mtu;
  929                                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
  930                                                 sctp_log_cwnd(stcb, net, net->mtu,
  931                                                     SCTP_CWND_LOG_FROM_CA);
  932                                         }
  933                                 } else {
  934                                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
  935                                                 sctp_log_cwnd(stcb, net, net->net_ack,
  936                                                     SCTP_CWND_LOG_NOADV_CA);
  937                                         }
  938                                 }
  939                         }
  940                 } else {
  941                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
  942                                 sctp_log_cwnd(stcb, net, net->mtu,
  943                                     SCTP_CWND_LOG_NO_CUMACK);
  944                         }
  945                 }
  946 skip_cwnd_update:
  947                 /*
  948                  * NOW, according to Karn's rule do we need to restore the
  949                  * RTO timer back? Check our net_ack2. If not set then we
  950                  * have a ambiguity.. i.e. all data ack'd was sent to more
  951                  * than one place.
  952                  */
  953                 if (net->net_ack2) {
  954                         /* restore any doubled timers */
  955                         net->RTO = ((net->lastsa >> 2) + net->lastsv) >> 1;
  956                         if (net->RTO < stcb->asoc.minrto) {
  957                                 net->RTO = stcb->asoc.minrto;
  958                         }
  959                         if (net->RTO > stcb->asoc.maxrto) {
  960                                 net->RTO = stcb->asoc.maxrto;
  961                         }
  962                 }
  963         }
  964 }
  965 
  966 
  967 /*
  968  * H-TCP congestion control. The algorithm is detailed in:
  969  * R.N.Shorten, D.J.Leith:
  970  *   "H-TCP: TCP for high-speed and long-distance networks"
  971  *   Proc. PFLDnet, Argonne, 2004.
  972  * http://www.hamilton.ie/net/htcp3.pdf
  973  */
  974 
  975 
  976 static int use_rtt_scaling = 1;
  977 static int use_bandwidth_switch = 1;
  978 
  979 static inline int
  980 between(uint32_t seq1, uint32_t seq2, uint32_t seq3)
  981 {
  982         return seq3 - seq2 >= seq1 - seq2;
  983 }
  984 
  985 static inline uint32_t
  986 htcp_cong_time(struct htcp *ca)
  987 {
  988         return sctp_get_tick_count() - ca->last_cong;
  989 }
  990 
  991 static inline uint32_t
  992 htcp_ccount(struct htcp *ca)
  993 {
  994         return htcp_cong_time(ca) / ca->minRTT;
  995 }
  996 
  997 static inline void
  998 htcp_reset(struct htcp *ca)
  999 {
 1000         ca->undo_last_cong = ca->last_cong;
 1001         ca->undo_maxRTT = ca->maxRTT;
 1002         ca->undo_old_maxB = ca->old_maxB;
 1003         ca->last_cong = sctp_get_tick_count();
 1004 }
 1005 
 1006 #ifdef SCTP_NOT_USED
 1007 
 1008 static uint32_t
 1009 htcp_cwnd_undo(struct sctp_tcb *stcb, struct sctp_nets *net)
 1010 {
 1011         net->htcp_ca.last_cong = net->htcp_ca.undo_last_cong;
 1012         net->htcp_ca.maxRTT = net->htcp_ca.undo_maxRTT;
 1013         net->htcp_ca.old_maxB = net->htcp_ca.undo_old_maxB;
 1014         return max(net->cwnd, ((net->ssthresh / net->mtu << 7) / net->htcp_ca.beta) * net->mtu);
 1015 }
 1016 
 1017 #endif
 1018 
 1019 static inline void
 1020 measure_rtt(struct sctp_tcb *stcb, struct sctp_nets *net)
 1021 {
 1022         uint32_t srtt = net->lastsa >> 3;
 1023 
 1024         /* keep track of minimum RTT seen so far, minRTT is zero at first */
 1025         if (net->htcp_ca.minRTT > srtt || !net->htcp_ca.minRTT)
 1026                 net->htcp_ca.minRTT = srtt;
 1027 
 1028         /* max RTT */
 1029         if (net->fast_retran_ip == 0 && net->ssthresh < 0xFFFF && htcp_ccount(&net->htcp_ca) > 3) {
 1030                 if (net->htcp_ca.maxRTT < net->htcp_ca.minRTT)
 1031                         net->htcp_ca.maxRTT = net->htcp_ca.minRTT;
 1032                 if (net->htcp_ca.maxRTT < srtt && srtt <= net->htcp_ca.maxRTT + MSEC_TO_TICKS(20))
 1033                         net->htcp_ca.maxRTT = srtt;
 1034         }
 1035 }
 1036 
 1037 static void
 1038 measure_achieved_throughput(struct sctp_tcb *stcb, struct sctp_nets *net)
 1039 {
 1040         uint32_t now = sctp_get_tick_count();
 1041 
 1042         if (net->fast_retran_ip == 0)
 1043                 net->htcp_ca.bytes_acked = net->net_ack;
 1044 
 1045         if (!use_bandwidth_switch)
 1046                 return;
 1047 
 1048         /* achieved throughput calculations */
 1049         /* JRS - not 100% sure of this statement */
 1050         if (net->fast_retran_ip == 1) {
 1051                 net->htcp_ca.bytecount = 0;
 1052                 net->htcp_ca.lasttime = now;
 1053                 return;
 1054         }
 1055         net->htcp_ca.bytecount += net->net_ack;
 1056 
 1057         if (net->htcp_ca.bytecount >= net->cwnd - ((net->htcp_ca.alpha >> 7 ? : 1) * net->mtu)
 1058             && now - net->htcp_ca.lasttime >= net->htcp_ca.minRTT
 1059             && net->htcp_ca.minRTT > 0) {
 1060                 uint32_t cur_Bi = net->htcp_ca.bytecount / net->mtu * hz / (now - net->htcp_ca.lasttime);
 1061 
 1062                 if (htcp_ccount(&net->htcp_ca) <= 3) {
 1063                         /* just after backoff */
 1064                         net->htcp_ca.minB = net->htcp_ca.maxB = net->htcp_ca.Bi = cur_Bi;
 1065                 } else {
 1066                         net->htcp_ca.Bi = (3 * net->htcp_ca.Bi + cur_Bi) / 4;
 1067                         if (net->htcp_ca.Bi > net->htcp_ca.maxB)
 1068                                 net->htcp_ca.maxB = net->htcp_ca.Bi;
 1069                         if (net->htcp_ca.minB > net->htcp_ca.maxB)
 1070                                 net->htcp_ca.minB = net->htcp_ca.maxB;
 1071                 }
 1072                 net->htcp_ca.bytecount = 0;
 1073                 net->htcp_ca.lasttime = now;
 1074         }
 1075 }
 1076 
 1077 static inline void
 1078 htcp_beta_update(struct htcp *ca, uint32_t minRTT, uint32_t maxRTT)
 1079 {
 1080         if (use_bandwidth_switch) {
 1081                 uint32_t maxB = ca->maxB;
 1082                 uint32_t old_maxB = ca->old_maxB;
 1083 
 1084                 ca->old_maxB = ca->maxB;
 1085 
 1086                 if (!between(5 * maxB, 4 * old_maxB, 6 * old_maxB)) {
 1087                         ca->beta = BETA_MIN;
 1088                         ca->modeswitch = 0;
 1089                         return;
 1090                 }
 1091         }
 1092         if (ca->modeswitch && minRTT > (uint32_t) MSEC_TO_TICKS(10) && maxRTT) {
 1093                 ca->beta = (minRTT << 7) / maxRTT;
 1094                 if (ca->beta < BETA_MIN)
 1095                         ca->beta = BETA_MIN;
 1096                 else if (ca->beta > BETA_MAX)
 1097                         ca->beta = BETA_MAX;
 1098         } else {
 1099                 ca->beta = BETA_MIN;
 1100                 ca->modeswitch = 1;
 1101         }
 1102 }
 1103 
 1104 static inline void
 1105 htcp_alpha_update(struct htcp *ca)
 1106 {
 1107         uint32_t minRTT = ca->minRTT;
 1108         uint32_t factor = 1;
 1109         uint32_t diff = htcp_cong_time(ca);
 1110 
 1111         if (diff > (uint32_t) hz) {
 1112                 diff -= hz;
 1113                 factor = 1 + (10 * diff + ((diff / 2) * (diff / 2) / hz)) / hz;
 1114         }
 1115         if (use_rtt_scaling && minRTT) {
 1116                 uint32_t scale = (hz << 3) / (10 * minRTT);
 1117 
 1118                 scale = min(max(scale, 1U << 2), 10U << 3);     /* clamping ratio to
 1119                                                                  * interval [0.5,10]<<3 */
 1120                 factor = (factor << 3) / scale;
 1121                 if (!factor)
 1122                         factor = 1;
 1123         }
 1124         ca->alpha = 2 * factor * ((1 << 7) - ca->beta);
 1125         if (!ca->alpha)
 1126                 ca->alpha = ALPHA_BASE;
 1127 }
 1128 
 1129 /* After we have the rtt data to calculate beta, we'd still prefer to wait one
 1130  * rtt before we adjust our beta to ensure we are working from a consistent
 1131  * data.
 1132  *
 1133  * This function should be called when we hit a congestion event since only at
 1134  * that point do we really have a real sense of maxRTT (the queues en route
 1135  * were getting just too full now).
 1136  */
 1137 static void
 1138 htcp_param_update(struct sctp_tcb *stcb, struct sctp_nets *net)
 1139 {
 1140         uint32_t minRTT = net->htcp_ca.minRTT;
 1141         uint32_t maxRTT = net->htcp_ca.maxRTT;
 1142 
 1143         htcp_beta_update(&net->htcp_ca, minRTT, maxRTT);
 1144         htcp_alpha_update(&net->htcp_ca);
 1145 
 1146         /*
 1147          * add slowly fading memory for maxRTT to accommodate routing
 1148          * changes etc
 1149          */
 1150         if (minRTT > 0 && maxRTT > minRTT)
 1151                 net->htcp_ca.maxRTT = minRTT + ((maxRTT - minRTT) * 95) / 100;
 1152 }
 1153 
 1154 static uint32_t
 1155 htcp_recalc_ssthresh(struct sctp_tcb *stcb, struct sctp_nets *net)
 1156 {
 1157         htcp_param_update(stcb, net);
 1158         return max(((net->cwnd / net->mtu * net->htcp_ca.beta) >> 7) * net->mtu, 2U * net->mtu);
 1159 }
 1160 
 1161 static void
 1162 htcp_cong_avoid(struct sctp_tcb *stcb, struct sctp_nets *net)
 1163 {
 1164         /*-
 1165          * How to handle these functions?
 1166          *      if (!tcp_is_cwnd_limited(sk, in_flight)) RRS - good question.
 1167          *              return;
 1168          */
 1169         if (net->cwnd <= net->ssthresh) {
 1170                 /* We are in slow start */
 1171                 if (net->flight_size + net->net_ack >= net->cwnd) {
 1172                         if (net->net_ack > (net->mtu * SCTP_BASE_SYSCTL(sctp_L2_abc_variable))) {
 1173                                 net->cwnd += (net->mtu * SCTP_BASE_SYSCTL(sctp_L2_abc_variable));
 1174                                 if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
 1175                                         sctp_log_cwnd(stcb, net, net->mtu,
 1176                                             SCTP_CWND_LOG_FROM_SS);
 1177                                 }
 1178                         } else {
 1179                                 net->cwnd += net->net_ack;
 1180                                 if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
 1181                                         sctp_log_cwnd(stcb, net, net->net_ack,
 1182                                             SCTP_CWND_LOG_FROM_SS);
 1183                                 }
 1184                         }
 1185                 } else {
 1186                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
 1187                                 sctp_log_cwnd(stcb, net, net->net_ack,
 1188                                     SCTP_CWND_LOG_NOADV_SS);
 1189                         }
 1190                 }
 1191         } else {
 1192                 measure_rtt(stcb, net);
 1193 
 1194                 /*
 1195                  * In dangerous area, increase slowly. In theory this is
 1196                  * net->cwnd += alpha / net->cwnd
 1197                  */
 1198                 /* What is snd_cwnd_cnt?? */
 1199                 if (((net->partial_bytes_acked / net->mtu * net->htcp_ca.alpha) >> 7) * net->mtu >= net->cwnd) {
 1200                         /*-
 1201                          * Does SCTP have a cwnd clamp?
 1202                          * if (net->snd_cwnd < net->snd_cwnd_clamp) - Nope (RRS).
 1203                          */
 1204                         net->cwnd += net->mtu;
 1205                         net->partial_bytes_acked = 0;
 1206                         htcp_alpha_update(&net->htcp_ca);
 1207                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
 1208                                 sctp_log_cwnd(stcb, net, net->mtu,
 1209                                     SCTP_CWND_LOG_FROM_CA);
 1210                         }
 1211                 } else {
 1212                         net->partial_bytes_acked += net->net_ack;
 1213                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
 1214                                 sctp_log_cwnd(stcb, net, net->net_ack,
 1215                                     SCTP_CWND_LOG_NOADV_CA);
 1216                         }
 1217                 }
 1218 
 1219                 net->htcp_ca.bytes_acked = net->mtu;
 1220         }
 1221 }
 1222 
 1223 #ifdef SCTP_NOT_USED
 1224 /* Lower bound on congestion window. */
 1225 static uint32_t
 1226 htcp_min_cwnd(struct sctp_tcb *stcb, struct sctp_nets *net)
 1227 {
 1228         return net->ssthresh;
 1229 }
 1230 
 1231 #endif
 1232 
 1233 static void
 1234 htcp_init(struct sctp_tcb *stcb, struct sctp_nets *net)
 1235 {
 1236         memset(&net->htcp_ca, 0, sizeof(struct htcp));
 1237         net->htcp_ca.alpha = ALPHA_BASE;
 1238         net->htcp_ca.beta = BETA_MIN;
 1239         net->htcp_ca.bytes_acked = net->mtu;
 1240         net->htcp_ca.last_cong = sctp_get_tick_count();
 1241 }
 1242 
 1243 void
 1244 sctp_htcp_set_initial_cc_param(struct sctp_tcb *stcb, struct sctp_nets *net)
 1245 {
 1246         /*
 1247          * We take the max of the burst limit times a MTU or the
 1248          * INITIAL_CWND. We then limit this to 4 MTU's of sending.
 1249          */
 1250         net->cwnd = min((net->mtu * 4), max((2 * net->mtu), SCTP_INITIAL_CWND));
 1251         net->ssthresh = stcb->asoc.peers_rwnd;
 1252         htcp_init(stcb, net);
 1253 
 1254         if (SCTP_BASE_SYSCTL(sctp_logging_level) & (SCTP_CWND_MONITOR_ENABLE | SCTP_CWND_LOGGING_ENABLE)) {
 1255                 sctp_log_cwnd(stcb, net, 0, SCTP_CWND_INITIALIZATION);
 1256         }
 1257 }
 1258 
 1259 void
 1260 sctp_htcp_cwnd_update_after_sack(struct sctp_tcb *stcb,
 1261     struct sctp_association *asoc,
 1262     int accum_moved, int reneged_all, int will_exit)
 1263 {
 1264         struct sctp_nets *net;
 1265 
 1266         /******************************/
 1267         /* update cwnd and Early FR   */
 1268         /******************************/
 1269         TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
 1270 
 1271 #ifdef JANA_CMT_FAST_RECOVERY
 1272                 /*
 1273                  * CMT fast recovery code. Need to debug.
 1274                  */
 1275                 if (net->fast_retran_loss_recovery && net->new_pseudo_cumack) {
 1276                         if (compare_with_wrap(asoc->last_acked_seq,
 1277                             net->fast_recovery_tsn, MAX_TSN) ||
 1278                             (asoc->last_acked_seq == net->fast_recovery_tsn) ||
 1279                             compare_with_wrap(net->pseudo_cumack, net->fast_recovery_tsn, MAX_TSN) ||
 1280                             (net->pseudo_cumack == net->fast_recovery_tsn)) {
 1281                                 net->will_exit_fast_recovery = 1;
 1282                         }
 1283                 }
 1284 #endif
 1285                 if (SCTP_BASE_SYSCTL(sctp_early_fr)) {
 1286                         /*
 1287                          * So, first of all do we need to have a Early FR
 1288                          * timer running?
 1289                          */
 1290                         if ((!TAILQ_EMPTY(&asoc->sent_queue) &&
 1291                             (net->ref_count > 1) &&
 1292                             (net->flight_size < net->cwnd)) ||
 1293                             (reneged_all)) {
 1294                                 /*
 1295                                  * yes, so in this case stop it if its
 1296                                  * running, and then restart it. Reneging
 1297                                  * all is a special case where we want to
 1298                                  * run the Early FR timer and then force the
 1299                                  * last few unacked to be sent, causing us
 1300                                  * to illicit a sack with gaps to force out
 1301                                  * the others.
 1302                                  */
 1303                                 if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
 1304                                         SCTP_STAT_INCR(sctps_earlyfrstpidsck2);
 1305                                         sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
 1306                                             SCTP_FROM_SCTP_INDATA + SCTP_LOC_20);
 1307                                 }
 1308                                 SCTP_STAT_INCR(sctps_earlyfrstrid);
 1309                                 sctp_timer_start(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net);
 1310                         } else {
 1311                                 /* No, stop it if its running */
 1312                                 if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
 1313                                         SCTP_STAT_INCR(sctps_earlyfrstpidsck3);
 1314                                         sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
 1315                                             SCTP_FROM_SCTP_INDATA + SCTP_LOC_21);
 1316                                 }
 1317                         }
 1318                 }
 1319                 /* if nothing was acked on this destination skip it */
 1320                 if (net->net_ack == 0) {
 1321                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
 1322                                 sctp_log_cwnd(stcb, net, 0, SCTP_CWND_LOG_FROM_SACK);
 1323                         }
 1324                         continue;
 1325                 }
 1326                 if (net->net_ack2 > 0) {
 1327                         /*
 1328                          * Karn's rule applies to clearing error count, this
 1329                          * is optional.
 1330                          */
 1331                         net->error_count = 0;
 1332                         if ((net->dest_state & SCTP_ADDR_NOT_REACHABLE) ==
 1333                             SCTP_ADDR_NOT_REACHABLE) {
 1334                                 /* addr came good */
 1335                                 net->dest_state &= ~SCTP_ADDR_NOT_REACHABLE;
 1336                                 net->dest_state |= SCTP_ADDR_REACHABLE;
 1337                                 sctp_ulp_notify(SCTP_NOTIFY_INTERFACE_UP, stcb,
 1338                                     SCTP_RECEIVED_SACK, (void *)net, SCTP_SO_NOT_LOCKED);
 1339                                 /* now was it the primary? if so restore */
 1340                                 if (net->dest_state & SCTP_ADDR_WAS_PRIMARY) {
 1341                                         (void)sctp_set_primary_addr(stcb, (struct sockaddr *)NULL, net);
 1342                                 }
 1343                         }
 1344                         /*
 1345                          * JRS 5/14/07 - If CMT PF is on and the destination
 1346                          * is in PF state, set the destination to active
 1347                          * state and set the cwnd to one or two MTU's based
 1348                          * on whether PF1 or PF2 is being used.
 1349                          * 
 1350                          * Should we stop any running T3 timer here?
 1351                          */
 1352                         if ((asoc->sctp_cmt_on_off == 1) &&
 1353                             (asoc->sctp_cmt_pf > 0) &&
 1354                             ((net->dest_state & SCTP_ADDR_PF) == SCTP_ADDR_PF)) {
 1355                                 net->dest_state &= ~SCTP_ADDR_PF;
 1356                                 net->cwnd = net->mtu * asoc->sctp_cmt_pf;
 1357                                 SCTPDBG(SCTP_DEBUG_INDATA1, "Destination %p moved from PF to reachable with cwnd %d.\n",
 1358                                     net, net->cwnd);
 1359                                 /*
 1360                                  * Since the cwnd value is explicitly set,
 1361                                  * skip the code that updates the cwnd
 1362                                  * value.
 1363                                  */
 1364                                 goto skip_cwnd_update;
 1365                         }
 1366                 }
 1367 #ifdef JANA_CMT_FAST_RECOVERY
 1368                 /*
 1369                  * CMT fast recovery code
 1370                  */
 1371                 /*
 1372                  * if (sctp_cmt_on_off == 1 &&
 1373                  * net->fast_retran_loss_recovery &&
 1374                  * net->will_exit_fast_recovery == 0) { @@@ Do something }
 1375                  * else if (sctp_cmt_on_off == 0 &&
 1376                  * asoc->fast_retran_loss_recovery && will_exit == 0) {
 1377                  */
 1378 #endif
 1379 
 1380                 if (asoc->fast_retran_loss_recovery &&
 1381                     will_exit == 0 &&
 1382                     (asoc->sctp_cmt_on_off == 0)) {
 1383                         /*
 1384                          * If we are in loss recovery we skip any cwnd
 1385                          * update
 1386                          */
 1387                         goto skip_cwnd_update;
 1388                 }
 1389                 /*
 1390                  * CMT: CUC algorithm. Update cwnd if pseudo-cumack has
 1391                  * moved.
 1392                  */
 1393                 if (accum_moved ||
 1394                     ((asoc->sctp_cmt_on_off == 1) && net->new_pseudo_cumack)) {
 1395                         htcp_cong_avoid(stcb, net);
 1396                         measure_achieved_throughput(stcb, net);
 1397                 } else {
 1398                         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
 1399                                 sctp_log_cwnd(stcb, net, net->mtu,
 1400                                     SCTP_CWND_LOG_NO_CUMACK);
 1401                         }
 1402                 }
 1403 skip_cwnd_update:
 1404                 /*
 1405                  * NOW, according to Karn's rule do we need to restore the
 1406                  * RTO timer back? Check our net_ack2. If not set then we
 1407                  * have a ambiguity.. i.e. all data ack'd was sent to more
 1408                  * than one place.
 1409                  */
 1410                 if (net->net_ack2) {
 1411                         /* restore any doubled timers */
 1412                         net->RTO = ((net->lastsa >> 2) + net->lastsv) >> 1;
 1413                         if (net->RTO < stcb->asoc.minrto) {
 1414                                 net->RTO = stcb->asoc.minrto;
 1415                         }
 1416                         if (net->RTO > stcb->asoc.maxrto) {
 1417                                 net->RTO = stcb->asoc.maxrto;
 1418                         }
 1419                 }
 1420         }
 1421 }
 1422 
 1423 void
 1424 sctp_htcp_cwnd_update_after_fr(struct sctp_tcb *stcb,
 1425     struct sctp_association *asoc)
 1426 {
 1427         struct sctp_nets *net;
 1428 
 1429         /*
 1430          * CMT fast recovery code. Need to debug. ((sctp_cmt_on_off == 1) &&
 1431          * (net->fast_retran_loss_recovery == 0)))
 1432          */
 1433         TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
 1434                 if ((asoc->fast_retran_loss_recovery == 0) ||
 1435                     (asoc->sctp_cmt_on_off == 1)) {
 1436                         /* out of a RFC2582 Fast recovery window? */
 1437                         if (net->net_ack > 0) {
 1438                                 /*
 1439                                  * per section 7.2.3, are there any
 1440                                  * destinations that had a fast retransmit
 1441                                  * to them. If so what we need to do is
 1442                                  * adjust ssthresh and cwnd.
 1443                                  */
 1444                                 struct sctp_tmit_chunk *lchk;
 1445                                 int old_cwnd = net->cwnd;
 1446 
 1447                                 /* JRS - reset as if state were changed */
 1448                                 htcp_reset(&net->htcp_ca);
 1449                                 net->ssthresh = htcp_recalc_ssthresh(stcb, net);
 1450                                 net->cwnd = net->ssthresh;
 1451                                 if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
 1452                                         sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd),
 1453                                             SCTP_CWND_LOG_FROM_FR);
 1454                                 }
 1455                                 lchk = TAILQ_FIRST(&asoc->send_queue);
 1456 
 1457                                 net->partial_bytes_acked = 0;
 1458                                 /* Turn on fast recovery window */
 1459                                 asoc->fast_retran_loss_recovery = 1;
 1460                                 if (lchk == NULL) {
 1461                                         /* Mark end of the window */
 1462                                         asoc->fast_recovery_tsn = asoc->sending_seq - 1;
 1463                                 } else {
 1464                                         asoc->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
 1465                                 }
 1466 
 1467                                 /*
 1468                                  * CMT fast recovery -- per destination
 1469                                  * recovery variable.
 1470                                  */
 1471                                 net->fast_retran_loss_recovery = 1;
 1472 
 1473                                 if (lchk == NULL) {
 1474                                         /* Mark end of the window */
 1475                                         net->fast_recovery_tsn = asoc->sending_seq - 1;
 1476                                 } else {
 1477                                         net->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
 1478                                 }
 1479 
 1480                                 /*
 1481                                  * Disable Nonce Sum Checking and store the
 1482                                  * resync tsn
 1483                                  */
 1484                                 asoc->nonce_sum_check = 0;
 1485                                 asoc->nonce_resync_tsn = asoc->fast_recovery_tsn + 1;
 1486 
 1487                                 sctp_timer_stop(SCTP_TIMER_TYPE_SEND,
 1488                                     stcb->sctp_ep, stcb, net, SCTP_FROM_SCTP_INDATA + SCTP_LOC_32);
 1489                                 sctp_timer_start(SCTP_TIMER_TYPE_SEND,
 1490                                     stcb->sctp_ep, stcb, net);
 1491                         }
 1492                 } else if (net->net_ack > 0) {
 1493                         /*
 1494                          * Mark a peg that we WOULD have done a cwnd
 1495                          * reduction but RFC2582 prevented this action.
 1496                          */
 1497                         SCTP_STAT_INCR(sctps_fastretransinrtt);
 1498                 }
 1499         }
 1500 }
 1501 
 1502 void
 1503 sctp_htcp_cwnd_update_after_timeout(struct sctp_tcb *stcb,
 1504     struct sctp_nets *net)
 1505 {
 1506         int old_cwnd = net->cwnd;
 1507 
 1508         /* JRS - reset as if the state were being changed to timeout */
 1509         htcp_reset(&net->htcp_ca);
 1510         net->ssthresh = htcp_recalc_ssthresh(stcb, net);
 1511         net->cwnd = net->mtu;
 1512         net->partial_bytes_acked = 0;
 1513         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
 1514                 sctp_log_cwnd(stcb, net, net->cwnd - old_cwnd, SCTP_CWND_LOG_FROM_RTX);
 1515         }
 1516 }
 1517 
 1518 void
 1519 sctp_htcp_cwnd_update_after_fr_timer(struct sctp_inpcb *inp,
 1520     struct sctp_tcb *stcb, struct sctp_nets *net)
 1521 {
 1522         int old_cwnd;
 1523 
 1524         old_cwnd = net->cwnd;
 1525 
 1526         sctp_chunk_output(inp, stcb, SCTP_OUTPUT_FROM_EARLY_FR_TMR, SCTP_SO_NOT_LOCKED);
 1527         net->htcp_ca.last_cong = sctp_get_tick_count();
 1528         /*
 1529          * make a small adjustment to cwnd and force to CA.
 1530          */
 1531         if (net->cwnd > net->mtu)
 1532                 /* drop down one MTU after sending */
 1533                 net->cwnd -= net->mtu;
 1534         if (net->cwnd < net->ssthresh)
 1535                 /* still in SS move to CA */
 1536                 net->ssthresh = net->cwnd - 1;
 1537         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
 1538                 sctp_log_cwnd(stcb, net, (old_cwnd - net->cwnd), SCTP_CWND_LOG_FROM_FR);
 1539         }
 1540 }
 1541 
 1542 void
 1543 sctp_htcp_cwnd_update_after_ecn_echo(struct sctp_tcb *stcb,
 1544     struct sctp_nets *net)
 1545 {
 1546         int old_cwnd;
 1547 
 1548         old_cwnd = net->cwnd;
 1549 
 1550         /* JRS - reset hctp as if state changed */
 1551         htcp_reset(&net->htcp_ca);
 1552         SCTP_STAT_INCR(sctps_ecnereducedcwnd);
 1553         net->ssthresh = htcp_recalc_ssthresh(stcb, net);
 1554         if (net->ssthresh < net->mtu) {
 1555                 net->ssthresh = net->mtu;
 1556                 /* here back off the timer as well, to slow us down */
 1557                 net->RTO <<= 1;
 1558         }
 1559         net->cwnd = net->ssthresh;
 1560         if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
 1561                 sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd), SCTP_CWND_LOG_FROM_SAT);
 1562         }
 1563 }

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