Pileus Git - ~andy/linux/blob - net/sctp/outqueue.c

   1 /* SCTP kernel implementation
   2  * (C) Copyright IBM Corp. 2001, 2004
   3  * Copyright (c) 1999-2000 Cisco, Inc.
   4  * Copyright (c) 1999-2001 Motorola, Inc.
   5  * Copyright (c) 2001-2003 Intel Corp.
   6  *
   7  * This file is part of the SCTP kernel implementation
   8  *
   9  * These functions implement the sctp_outq class.   The outqueue handles
  10  * bundling and queueing of outgoing SCTP chunks.
  11  *
  12  * This SCTP implementation is free software;
  13  * you can redistribute it and/or modify it under the terms of
  14  * the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2, or (at your option)
  16  * any later version.
  17  *
  18  * This SCTP implementation is distributed in the hope that it
  19  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  20  *                 ************************
  21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  22  * See the GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with GNU CC; see the file COPYING.  If not, write to
  26  * the Free Software Foundation, 59 Temple Place - Suite 330,
  27  * Boston, MA 02111-1307, USA.
  28  *
  29  * Please send any bug reports or fixes you make to the
  30  * email address(es):
  31  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  32  *
  33  * Or submit a bug report through the following website:
  34  *    http://www.sf.net/projects/lksctp
  35  *
  36  * Written or modified by:
  37  *    La Monte H.P. Yarroll <piggy@acm.org>
  38  *    Karl Knutson          <karl@athena.chicago.il.us>
  39  *    Perry Melange         <pmelange@null.cc.uic.edu>
  40  *    Xingang Guo           <xingang.guo@intel.com>
  41  *    Hui Huang             <hui.huang@nokia.com>
  42  *    Sridhar Samudrala     <sri@us.ibm.com>
  43  *    Jon Grimm             <jgrimm@us.ibm.com>
  44  *
  45  * Any bugs reported given to us we will try to fix... any fixes shared will
  46  * be incorporated into the next SCTP release.
  47  */
  48
  49 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  50
  51 #include <linux/types.h>
  52 #include <linux/list.h>   /* For struct list_head */
  53 #include <linux/socket.h>
  54 #include <linux/ip.h>
  55 #include <linux/slab.h>
  56 #include <net/sock.h>     /* For skb_set_owner_w */
  57
  58 #include <net/sctp/sctp.h>
  59 #include <net/sctp/sm.h>
  60
  61 /* Declare internal functions here.  */
  62 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
  63 static void sctp_check_transmitted(struct sctp_outq *q,
  64                                    struct list_head *transmitted_queue,
  65                                    struct sctp_transport *transport,
  66                                    union sctp_addr *saddr,
  67                                    struct sctp_sackhdr *sack,
  68                                    __u32 *highest_new_tsn);
  69
  70 static void sctp_mark_missing(struct sctp_outq *q,
  71                               struct list_head *transmitted_queue,
  72                               struct sctp_transport *transport,
  73                               __u32 highest_new_tsn,
  74                               int count_of_newacks);
  75
  76 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);
  77
  78 static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout);
  79
  80 /* Add data to the front of the queue. */
  81 static inline void sctp_outq_head_data(struct sctp_outq *q,
  82                                         struct sctp_chunk *ch)
  83 {
  84         list_add(&ch->list, &q->out_chunk_list);
  85         q->out_qlen += ch->skb->len;
  86 }
  87
  88 /* Take data from the front of the queue. */
  89 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
  90 {
  91         struct sctp_chunk *ch = NULL;
  92
  93         if (!list_empty(&q->out_chunk_list)) {
  94                 struct list_head *entry = q->out_chunk_list.next;
  95
  96                 ch = list_entry(entry, struct sctp_chunk, list);
  97                 list_del_init(entry);
  98                 q->out_qlen -= ch->skb->len;
  99         }
 100         return ch;
 101 }
 102 /* Add data chunk to the end of the queue. */
 103 static inline void sctp_outq_tail_data(struct sctp_outq *q,
 104                                        struct sctp_chunk *ch)
 105 {
 106         list_add_tail(&ch->list, &q->out_chunk_list);
 107         q->out_qlen += ch->skb->len;
 108 }
 109
 110 /*
 111  * SFR-CACC algorithm:
 112  * D) If count_of_newacks is greater than or equal to 2
 113  * and t was not sent to the current primary then the
 114  * sender MUST NOT increment missing report count for t.
 115  */
 116 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
 117                                        struct sctp_transport *transport,
 118                                        int count_of_newacks)
 119 {
 120         if (count_of_newacks >=2 && transport != primary)
 121                 return 1;
 122         return 0;
 123 }
 124
 125 /*
 126  * SFR-CACC algorithm:
 127  * F) If count_of_newacks is less than 2, let d be the
 128  * destination to which t was sent. If cacc_saw_newack
 129  * is 0 for destination d, then the sender MUST NOT
 130  * increment missing report count for t.
 131  */
 132 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
 133                                        int count_of_newacks)
 134 {
 135         if (count_of_newacks < 2 &&
 136                         (transport && !transport->cacc.cacc_saw_newack))
 137                 return 1;
 138         return 0;
 139 }
 140
 141 /*
 142  * SFR-CACC algorithm:
 143  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
 144  * execute steps C, D, F.
 145  *
 146  * C has been implemented in sctp_outq_sack
 147  */
 148 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
 149                                      struct sctp_transport *transport,
 150                                      int count_of_newacks)
 151 {
 152         if (!primary->cacc.cycling_changeover) {
 153                 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
 154                         return 1;
 155                 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
 156                         return 1;
 157                 return 0;
 158         }
 159         return 0;
 160 }
 161
 162 /*
 163  * SFR-CACC algorithm:
 164  * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
 165  * than next_tsn_at_change of the current primary, then
 166  * the sender MUST NOT increment missing report count
 167  * for t.
 168  */
 169 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
 170 {
 171         if (primary->cacc.cycling_changeover &&
 172             TSN_lt(tsn, primary->cacc.next_tsn_at_change))
 173                 return 1;
 174         return 0;
 175 }
 176
 177 /*
 178  * SFR-CACC algorithm:
 179  * 3) If the missing report count for TSN t is to be
 180  * incremented according to [RFC2960] and
 181  * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
 182  * then the sender MUST further execute steps 3.1 and
 183  * 3.2 to determine if the missing report count for
 184  * TSN t SHOULD NOT be incremented.
 185  *
 186  * 3.3) If 3.1 and 3.2 do not dictate that the missing
 187  * report count for t should not be incremented, then
 188  * the sender SHOULD increment missing report count for
 189  * t (according to [RFC2960] and [SCTP_STEWART_2002]).
 190  */
 191 static inline int sctp_cacc_skip(struct sctp_transport *primary,
 192                                  struct sctp_transport *transport,
 193                                  int count_of_newacks,
 194                                  __u32 tsn)
 195 {
 196         if (primary->cacc.changeover_active &&
 197             (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
 198              sctp_cacc_skip_3_2(primary, tsn)))
 199                 return 1;
 200         return 0;
 201 }
 202
 203 /* Initialize an existing sctp_outq.  This does the boring stuff.
 204  * You still need to define handlers if you really want to DO
 205  * something with this structure...
 206  */
 207 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
 208 {
 209         q->asoc = asoc;
 210         INIT_LIST_HEAD(&q->out_chunk_list);
 211         INIT_LIST_HEAD(&q->control_chunk_list);
 212         INIT_LIST_HEAD(&q->retransmit);
 213         INIT_LIST_HEAD(&q->sacked);
 214         INIT_LIST_HEAD(&q->abandoned);
 215
 216         q->fast_rtx = 0;
 217         q->outstanding_bytes = 0;
 218         q->empty = 1;
 219         q->cork  = 0;
 220
 221         q->malloced = 0;
 222         q->out_qlen = 0;
 223 }
 224
 225 /* Free the outqueue structure and any related pending chunks.
 226  */
 227 static void __sctp_outq_teardown(struct sctp_outq *q)
 228 {
 229         struct sctp_transport *transport;
 230         struct list_head *lchunk, *temp;
 231         struct sctp_chunk *chunk, *tmp;
 232
 233         /* Throw away unacknowledged chunks. */
 234         list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
 235                         transports) {
 236                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
 237                         chunk = list_entry(lchunk, struct sctp_chunk,
 238                                            transmitted_list);
 239                         /* Mark as part of a failed message. */
 240                         sctp_chunk_fail(chunk, q->error);
 241                         sctp_chunk_free(chunk);
 242                 }
 243         }
 244
 245         /* Throw away chunks that have been gap ACKed.  */
 246         list_for_each_safe(lchunk, temp, &q->sacked) {
 247                 list_del_init(lchunk);
 248                 chunk = list_entry(lchunk, struct sctp_chunk,
 249                                    transmitted_list);
 250                 sctp_chunk_fail(chunk, q->error);
 251                 sctp_chunk_free(chunk);
 252         }
 253
 254         /* Throw away any chunks in the retransmit queue. */
 255         list_for_each_safe(lchunk, temp, &q->retransmit) {
 256                 list_del_init(lchunk);
 257                 chunk = list_entry(lchunk, struct sctp_chunk,
 258                                    transmitted_list);
 259                 sctp_chunk_fail(chunk, q->error);
 260                 sctp_chunk_free(chunk);
 261         }
 262
 263         /* Throw away any chunks that are in the abandoned queue. */
 264         list_for_each_safe(lchunk, temp, &q->abandoned) {
 265                 list_del_init(lchunk);
 266                 chunk = list_entry(lchunk, struct sctp_chunk,
 267                                    transmitted_list);
 268                 sctp_chunk_fail(chunk, q->error);
 269                 sctp_chunk_free(chunk);
 270         }
 271
 272         /* Throw away any leftover data chunks. */
 273         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 274
 275                 /* Mark as send failure. */
 276                 sctp_chunk_fail(chunk, q->error);
 277                 sctp_chunk_free(chunk);
 278         }
 279
 280         /* Throw away any leftover control chunks. */
 281         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 282                 list_del_init(&chunk->list);
 283                 sctp_chunk_free(chunk);
 284         }
 285 }
 286
 287 void sctp_outq_teardown(struct sctp_outq *q)
 288 {
 289         __sctp_outq_teardown(q);
 290         sctp_outq_init(q->asoc, q);
 291 }
 292
 293 /* Free the outqueue structure and any related pending chunks.  */
 294 void sctp_outq_free(struct sctp_outq *q)
 295 {
 296         /* Throw away leftover chunks. */
 297         __sctp_outq_teardown(q);
 298
 299         /* If we were kmalloc()'d, free the memory.  */
 300         if (q->malloced)
 301                 kfree(q);
 302 }
 303
 304 /* Put a new chunk in an sctp_outq.  */
 305 int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
 306 {
 307         struct net *net = sock_net(q->asoc->base.sk);
 308         int error = 0;
 309
 310         SCTP_DEBUG_PRINTK("sctp_outq_tail(%p, %p[%s])\n",
 311                           q, chunk, chunk && chunk->chunk_hdr ?
 312                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
 313                           : "Illegal Chunk");
 314
 315         /* If it is data, queue it up, otherwise, send it
 316          * immediately.
 317          */
 318         if (sctp_chunk_is_data(chunk)) {
 319                 /* Is it OK to queue data chunks?  */
 320                 /* From 9. Termination of Association
 321                  *
 322                  * When either endpoint performs a shutdown, the
 323                  * association on each peer will stop accepting new
 324                  * data from its user and only deliver data in queue
 325                  * at the time of sending or receiving the SHUTDOWN
 326                  * chunk.
 327                  */
 328                 switch (q->asoc->state) {
 329                 case SCTP_STATE_CLOSED:
 330                 case SCTP_STATE_SHUTDOWN_PENDING:
 331                 case SCTP_STATE_SHUTDOWN_SENT:
 332                 case SCTP_STATE_SHUTDOWN_RECEIVED:
 333                 case SCTP_STATE_SHUTDOWN_ACK_SENT:
 334                         /* Cannot send after transport endpoint shutdown */
 335                         error = -ESHUTDOWN;
 336                         break;
 337
 338                 default:
 339                         SCTP_DEBUG_PRINTK("outqueueing (%p, %p[%s])\n",
 340                           q, chunk, chunk && chunk->chunk_hdr ?
 341                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
 342                           : "Illegal Chunk");
 343
 344                         sctp_outq_tail_data(q, chunk);
 345                         if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
 346                                 SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
 347                         else
 348                                 SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
 349                         q->empty = 0;
 350                         break;
 351                 }
 352         } else {
 353                 list_add_tail(&chunk->list, &q->control_chunk_list);
 354                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 355         }
 356
 357         if (error < 0)
 358                 return error;
 359
 360         if (!q->cork)
 361                 error = sctp_outq_flush(q, 0);
 362
 363         return error;
 364 }
 365
 366 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
 367  * and the abandoned list are in ascending order.
 368  */
 369 static void sctp_insert_list(struct list_head *head, struct list_head *new)
 370 {
 371         struct list_head *pos;
 372         struct sctp_chunk *nchunk, *lchunk;
 373         __u32 ntsn, ltsn;
 374         int done = 0;
 375
 376         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
 377         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
 378
 379         list_for_each(pos, head) {
 380                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
 381                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
 382                 if (TSN_lt(ntsn, ltsn)) {
 383                         list_add(new, pos->prev);
 384                         done = 1;
 385                         break;
 386                 }
 387         }
 388         if (!done)
 389                 list_add_tail(new, head);
 390 }
 391
 392 /* Mark all the eligible packets on a transport for retransmission.  */
 393 void sctp_retransmit_mark(struct sctp_outq *q,
 394                           struct sctp_transport *transport,
 395                           __u8 reason)
 396 {
 397         struct list_head *lchunk, *ltemp;
 398         struct sctp_chunk *chunk;
 399
 400         /* Walk through the specified transmitted queue.  */
 401         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
 402                 chunk = list_entry(lchunk, struct sctp_chunk,
 403                                    transmitted_list);
 404
 405                 /* If the chunk is abandoned, move it to abandoned list. */
 406                 if (sctp_chunk_abandoned(chunk)) {
 407                         list_del_init(lchunk);
 408                         sctp_insert_list(&q->abandoned, lchunk);
 409
 410                         /* If this chunk has not been previousely acked,
 411                          * stop considering it 'outstanding'.  Our peer
 412                          * will most likely never see it since it will
 413                          * not be retransmitted
 414                          */
 415                         if (!chunk->tsn_gap_acked) {
 416                                 if (chunk->transport)
 417                                         chunk->transport->flight_size -=
 418                                                         sctp_data_size(chunk);
 419                                 q->outstanding_bytes -= sctp_data_size(chunk);
 420                                 q->asoc->peer.rwnd += sctp_data_size(chunk);
 421                         }
 422                         continue;
 423                 }
 424
 425                 /* If we are doing  retransmission due to a timeout or pmtu
 426                  * discovery, only the  chunks that are not yet acked should
 427                  * be added to the retransmit queue.
 428                  */
 429                 if ((reason == SCTP_RTXR_FAST_RTX  &&
 430                             (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
 431                     (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
 432                         /* RFC 2960 6.2.1 Processing a Received SACK
 433                          *
 434                          * C) Any time a DATA chunk is marked for
 435                          * retransmission (via either T3-rtx timer expiration
 436                          * (Section 6.3.3) or via fast retransmit
 437                          * (Section 7.2.4)), add the data size of those
 438                          * chunks to the rwnd.
 439                          */
 440                         q->asoc->peer.rwnd += sctp_data_size(chunk);
 441                         q->outstanding_bytes -= sctp_data_size(chunk);
 442                         if (chunk->transport)
 443                                 transport->flight_size -= sctp_data_size(chunk);
 444
 445                         /* sctpimpguide-05 Section 2.8.2
 446                          * M5) If a T3-rtx timer expires, the
 447                          * 'TSN.Missing.Report' of all affected TSNs is set
 448                          * to 0.
 449                          */
 450                         chunk->tsn_missing_report = 0;
 451
 452                         /* If a chunk that is being used for RTT measurement
 453                          * has to be retransmitted, we cannot use this chunk
 454                          * anymore for RTT measurements. Reset rto_pending so
 455                          * that a new RTT measurement is started when a new
 456                          * data chunk is sent.
 457                          */
 458                         if (chunk->rtt_in_progress) {
 459                                 chunk->rtt_in_progress = 0;
 460                                 transport->rto_pending = 0;
 461                         }
 462
 463                         /* Move the chunk to the retransmit queue. The chunks
 464                          * on the retransmit queue are always kept in order.
 465                          */
 466                         list_del_init(lchunk);
 467                         sctp_insert_list(&q->retransmit, lchunk);
 468                 }
 469         }
 470
 471         SCTP_DEBUG_PRINTK("%s: transport: %p, reason: %d, "
 472                           "cwnd: %d, ssthresh: %d, flight_size: %d, "
 473                           "pba: %d\n", __func__,
 474                           transport, reason,
 475                           transport->cwnd, transport->ssthresh,
 476                           transport->flight_size,
 477                           transport->partial_bytes_acked);
 478
 479 }
 480
 481 /* Mark all the eligible packets on a transport for retransmission and force
 482  * one packet out.
 483  */
 484 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
 485                      sctp_retransmit_reason_t reason)
 486 {
 487         struct net *net = sock_net(q->asoc->base.sk);
 488         int error = 0;
 489
 490         switch(reason) {
 491         case SCTP_RTXR_T3_RTX:
 492                 SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
 493                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
 494                 /* Update the retran path if the T3-rtx timer has expired for
 495                  * the current retran path.
 496                  */
 497                 if (transport == transport->asoc->peer.retran_path)
 498                         sctp_assoc_update_retran_path(transport->asoc);
 499                 transport->asoc->rtx_data_chunks +=
 500                         transport->asoc->unack_data;
 501                 break;
 502         case SCTP_RTXR_FAST_RTX:
 503                 SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
 504                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
 505                 q->fast_rtx = 1;
 506                 break;
 507         case SCTP_RTXR_PMTUD:
 508                 SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
 509                 break;
 510         case SCTP_RTXR_T1_RTX:
 511                 SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
 512                 transport->asoc->init_retries++;
 513                 break;
 514         default:
 515                 BUG();
 516         }
 517
 518         sctp_retransmit_mark(q, transport, reason);
 519
 520         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
 521          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
 522          * following the procedures outlined in C1 - C5.
 523          */
 524         if (reason == SCTP_RTXR_T3_RTX)
 525                 sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
 526
 527         /* Flush the queues only on timeout, since fast_rtx is only
 528          * triggered during sack processing and the queue
 529          * will be flushed at the end.
 530          */
 531         if (reason != SCTP_RTXR_FAST_RTX)
 532                 error = sctp_outq_flush(q, /* rtx_timeout */ 1);
 533
 534         if (error)
 535                 q->asoc->base.sk->sk_err = -error;
 536 }
 537
 538 /*
 539  * Transmit DATA chunks on the retransmit queue.  Upon return from
 540  * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
 541  * need to be transmitted by the caller.
 542  * We assume that pkt->transport has already been set.
 543  *
 544  * The return value is a normal kernel error return value.
 545  */
 546 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 547                                int rtx_timeout, int *start_timer)
 548 {
 549         struct list_head *lqueue;
 550         struct sctp_transport *transport = pkt->transport;
 551         sctp_xmit_t status;
 552         struct sctp_chunk *chunk, *chunk1;
 553         int fast_rtx;
 554         int error = 0;
 555         int timer = 0;
 556         int done = 0;
 557
 558         lqueue = &q->retransmit;
 559         fast_rtx = q->fast_rtx;
 560
 561         /* This loop handles time-out retransmissions, fast retransmissions,
 562          * and retransmissions due to opening of whindow.
 563          *
 564          * RFC 2960 6.3.3 Handle T3-rtx Expiration
 565          *
 566          * E3) Determine how many of the earliest (i.e., lowest TSN)
 567          * outstanding DATA chunks for the address for which the
 568          * T3-rtx has expired will fit into a single packet, subject
 569          * to the MTU constraint for the path corresponding to the
 570          * destination transport address to which the retransmission
 571          * is being sent (this may be different from the address for
 572          * which the timer expires [see Section 6.4]). Call this value
 573          * K. Bundle and retransmit those K DATA chunks in a single
 574          * packet to the destination endpoint.
 575          *
 576          * [Just to be painfully clear, if we are retransmitting
 577          * because a timeout just happened, we should send only ONE
 578          * packet of retransmitted data.]
 579          *
 580          * For fast retransmissions we also send only ONE packet.  However,
 581          * if we are just flushing the queue due to open window, we'll
 582          * try to send as much as possible.
 583          */
 584         list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
 585                 /* If the chunk is abandoned, move it to abandoned list. */
 586                 if (sctp_chunk_abandoned(chunk)) {
 587                         list_del_init(&chunk->transmitted_list);
 588                         sctp_insert_list(&q->abandoned,
 589                                          &chunk->transmitted_list);
 590                         continue;
 591                 }
 592
 593                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
 594                  * simple approach is just to move such TSNs out of the
 595                  * way and into a 'transmitted' queue and skip to the
 596                  * next chunk.
 597                  */
 598                 if (chunk->tsn_gap_acked) {
 599                         list_move_tail(&chunk->transmitted_list,
 600                                        &transport->transmitted);
 601                         continue;
 602                 }
 603
 604                 /* If we are doing fast retransmit, ignore non-fast_rtransmit
 605                  * chunks
 606                  */
 607                 if (fast_rtx && !chunk->fast_retransmit)
 608                         continue;
 609
 610 redo:
 611                 /* Attempt to append this chunk to the packet. */
 612                 status = sctp_packet_append_chunk(pkt, chunk);
 613
 614                 switch (status) {
 615                 case SCTP_XMIT_PMTU_FULL:
 616                         if (!pkt->has_data && !pkt->has_cookie_echo) {
 617                                 /* If this packet did not contain DATA then
 618                                  * retransmission did not happen, so do it
 619                                  * again.  We'll ignore the error here since
 620                                  * control chunks are already freed so there
 621                                  * is nothing we can do.
 622                                  */
 623                                 sctp_packet_transmit(pkt);
 624                                 goto redo;
 625                         }
 626
 627                         /* Send this packet.  */
 628                         error = sctp_packet_transmit(pkt);
 629
 630                         /* If we are retransmitting, we should only
 631                          * send a single packet.
 632                          * Otherwise, try appending this chunk again.
 633                          */
 634                         if (rtx_timeout || fast_rtx)
 635                                 done = 1;
 636                         else
 637                                 goto redo;
 638
 639                         /* Bundle next chunk in the next round.  */
 640                         break;
 641
 642                 case SCTP_XMIT_RWND_FULL:
 643                         /* Send this packet. */
 644                         error = sctp_packet_transmit(pkt);
 645
 646                         /* Stop sending DATA as there is no more room
 647                          * at the receiver.
 648                          */
 649                         done = 1;
 650                         break;
 651
 652                 case SCTP_XMIT_NAGLE_DELAY:
 653                         /* Send this packet. */
 654                         error = sctp_packet_transmit(pkt);
 655
 656                         /* Stop sending DATA because of nagle delay. */
 657                         done = 1;
 658                         break;
 659
 660                 default:
 661                         /* The append was successful, so add this chunk to
 662                          * the transmitted list.
 663                          */
 664                         list_move_tail(&chunk->transmitted_list,
 665                                        &transport->transmitted);
 666
 667                         /* Mark the chunk as ineligible for fast retransmit
 668                          * after it is retransmitted.
 669                          */
 670                         if (chunk->fast_retransmit == SCTP_NEED_FRTX)
 671                                 chunk->fast_retransmit = SCTP_DONT_FRTX;
 672
 673                         q->empty = 0;
 674                         q->asoc->stats.rtxchunks++;
 675                         break;
 676                 }
 677
 678                 /* Set the timer if there were no errors */
 679                 if (!error && !timer)
 680                         timer = 1;
 681
 682                 if (done)
 683                         break;
 684         }
 685
 686         /* If we are here due to a retransmit timeout or a fast
 687          * retransmit and if there are any chunks left in the retransmit
 688          * queue that could not fit in the PMTU sized packet, they need
 689          * to be marked as ineligible for a subsequent fast retransmit.
 690          */
 691         if (rtx_timeout || fast_rtx) {
 692                 list_for_each_entry(chunk1, lqueue, transmitted_list) {
 693                         if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
 694                                 chunk1->fast_retransmit = SCTP_DONT_FRTX;
 695                 }
 696         }
 697
 698         *start_timer = timer;
 699
 700         /* Clear fast retransmit hint */
 701         if (fast_rtx)
 702                 q->fast_rtx = 0;
 703
 704         return error;
 705 }
 706
 707 /* Cork the outqueue so queued chunks are really queued. */
 708 int sctp_outq_uncork(struct sctp_outq *q)
 709 {
 710         int error = 0;
 711         if (q->cork)
 712                 q->cork = 0;
 713         error = sctp_outq_flush(q, 0);
 714         return error;
 715 }
 716
 717
 718 /*
 719  * Try to flush an outqueue.
 720  *
 721  * Description: Send everything in q which we legally can, subject to
 722  * congestion limitations.
 723  * * Note: This function can be called from multiple contexts so appropriate
 724  * locking concerns must be made.  Today we use the sock lock to protect
 725  * this function.
 726  */
 727 static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
 728 {
 729         struct sctp_packet *packet;
 730         struct sctp_packet singleton;
 731         struct sctp_association *asoc = q->asoc;
 732         __u16 sport = asoc->base.bind_addr.port;
 733         __u16 dport = asoc->peer.port;
 734         __u32 vtag = asoc->peer.i.init_tag;
 735         struct sctp_transport *transport = NULL;
 736         struct sctp_transport *new_transport;
 737         struct sctp_chunk *chunk, *tmp;
 738         sctp_xmit_t status;
 739         int error = 0;
 740         int start_timer = 0;
 741         int one_packet = 0;
 742
 743         /* These transports have chunks to send. */
 744         struct list_head transport_list;
 745         struct list_head *ltransport;
 746
 747         INIT_LIST_HEAD(&transport_list);
 748         packet = NULL;
 749
 750         /*
 751          * 6.10 Bundling
 752          *   ...
 753          *   When bundling control chunks with DATA chunks, an
 754          *   endpoint MUST place control chunks first in the outbound
 755          *   SCTP packet.  The transmitter MUST transmit DATA chunks
 756          *   within a SCTP packet in increasing order of TSN.
 757          *   ...
 758          */
 759
 760         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 761                 /* RFC 5061, 5.3
 762                  * F1) This means that until such time as the ASCONF
 763                  * containing the add is acknowledged, the sender MUST
 764                  * NOT use the new IP address as a source for ANY SCTP
 765                  * packet except on carrying an ASCONF Chunk.
 766                  */
 767                 if (asoc->src_out_of_asoc_ok &&
 768                     chunk->chunk_hdr->type != SCTP_CID_ASCONF)
 769                         continue;
 770
 771                 list_del_init(&chunk->list);
 772
 773                 /* Pick the right transport to use. */
 774                 new_transport = chunk->transport;
 775
 776                 if (!new_transport) {
 777                         /*
 778                          * If we have a prior transport pointer, see if
 779                          * the destination address of the chunk
 780                          * matches the destination address of the
 781                          * current transport.  If not a match, then
 782                          * try to look up the transport with a given
 783                          * destination address.  We do this because
 784                          * after processing ASCONFs, we may have new
 785                          * transports created.
 786                          */
 787                         if (transport &&
 788                             sctp_cmp_addr_exact(&chunk->dest,
 789                                                 &transport->ipaddr))
 790                                         new_transport = transport;
 791                         else
 792                                 new_transport = sctp_assoc_lookup_paddr(asoc,
 793                                                                 &chunk->dest);
 794
 795                         /* if we still don't have a new transport, then
 796                          * use the current active path.
 797                          */
 798                         if (!new_transport)
 799                                 new_transport = asoc->peer.active_path;
 800                 } else if ((new_transport->state == SCTP_INACTIVE) ||
 801                            (new_transport->state == SCTP_UNCONFIRMED) ||
 802                            (new_transport->state == SCTP_PF)) {
 803                         /* If the chunk is Heartbeat or Heartbeat Ack,
 804                          * send it to chunk->transport, even if it's
 805                          * inactive.
 806                          *
 807                          * 3.3.6 Heartbeat Acknowledgement:
 808                          * ...
 809                          * A HEARTBEAT ACK is always sent to the source IP
 810                          * address of the IP datagram containing the
 811                          * HEARTBEAT chunk to which this ack is responding.
 812                          * ...
 813                          *
 814                          * ASCONF_ACKs also must be sent to the source.
 815                          */
 816                         if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
 817                             chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK &&
 818                             chunk->chunk_hdr->type != SCTP_CID_ASCONF_ACK)
 819                                 new_transport = asoc->peer.active_path;
 820                 }
 821
 822                 /* Are we switching transports?
 823                  * Take care of transport locks.
 824                  */
 825                 if (new_transport != transport) {
 826                         transport = new_transport;
 827                         if (list_empty(&transport->send_ready)) {
 828                                 list_add_tail(&transport->send_ready,
 829                                               &transport_list);
 830                         }
 831                         packet = &transport->packet;
 832                         sctp_packet_config(packet, vtag,
 833                                            asoc->peer.ecn_capable);
 834                 }
 835
 836                 switch (chunk->chunk_hdr->type) {
 837                 /*
 838                  * 6.10 Bundling
 839                  *   ...
 840                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
 841                  *   COMPLETE with any other chunks.  [Send them immediately.]
 842                  */
 843                 case SCTP_CID_INIT:
 844                 case SCTP_CID_INIT_ACK:
 845                 case SCTP_CID_SHUTDOWN_COMPLETE:
 846                         sctp_packet_init(&singleton, transport, sport, dport);
 847                         sctp_packet_config(&singleton, vtag, 0);
 848                         sctp_packet_append_chunk(&singleton, chunk);
 849                         error = sctp_packet_transmit(&singleton);
 850                         if (error < 0)
 851                                 return error;
 852                         break;
 853
 854                 case SCTP_CID_ABORT:
 855                         if (sctp_test_T_bit(chunk)) {
 856                                 packet->vtag = asoc->c.my_vtag;
 857                         }
 858                 /* The following chunks are "response" chunks, i.e.
 859                  * they are generated in response to something we
 860                  * received.  If we are sending these, then we can
 861                  * send only 1 packet containing these chunks.
 862                  */
 863                 case SCTP_CID_HEARTBEAT_ACK:
 864                 case SCTP_CID_SHUTDOWN_ACK:
 865                 case SCTP_CID_COOKIE_ACK:
 866                 case SCTP_CID_COOKIE_ECHO:
 867                 case SCTP_CID_ERROR:
 868                 case SCTP_CID_ECN_CWR:
 869                 case SCTP_CID_ASCONF_ACK:
 870                         one_packet = 1;
 871                         /* Fall through */
 872
 873                 case SCTP_CID_SACK:
 874                 case SCTP_CID_HEARTBEAT:
 875                 case SCTP_CID_SHUTDOWN:
 876                 case SCTP_CID_ECN_ECNE:
 877                 case SCTP_CID_ASCONF:
 878                 case SCTP_CID_FWD_TSN:
 879                         status = sctp_packet_transmit_chunk(packet, chunk,
 880                                                             one_packet);
 881                         if (status  != SCTP_XMIT_OK) {
 882                                 /* put the chunk back */
 883                                 list_add(&chunk->list, &q->control_chunk_list);
 884                         } else {
 885                                 asoc->stats.octrlchunks++;
 886                                 /* PR-SCTP C5) If a FORWARD TSN is sent, the
 887                                  * sender MUST assure that at least one T3-rtx
 888                                  * timer is running.
 889                                  */
 890                                 if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN)
 891                                         sctp_transport_reset_timers(transport);
 892                         }
 893                         break;
 894
 895                 default:
 896                         /* We built a chunk with an illegal type! */
 897                         BUG();
 898                 }
 899         }
 900
 901         if (q->asoc->src_out_of_asoc_ok)
 902                 goto sctp_flush_out;
 903
 904         /* Is it OK to send data chunks?  */
 905         switch (asoc->state) {
 906         case SCTP_STATE_COOKIE_ECHOED:
 907                 /* Only allow bundling when this packet has a COOKIE-ECHO
 908                  * chunk.
 909                  */
 910                 if (!packet || !packet->has_cookie_echo)
 911                         break;
 912
 913                 /* fallthru */
 914         case SCTP_STATE_ESTABLISHED:
 915         case SCTP_STATE_SHUTDOWN_PENDING:
 916         case SCTP_STATE_SHUTDOWN_RECEIVED:
 917                 /*
 918                  * RFC 2960 6.1  Transmission of DATA Chunks
 919                  *
 920                  * C) When the time comes for the sender to transmit,
 921                  * before sending new DATA chunks, the sender MUST
 922                  * first transmit any outstanding DATA chunks which
 923                  * are marked for retransmission (limited by the
 924                  * current cwnd).
 925                  */
 926                 if (!list_empty(&q->retransmit)) {
 927                         if (asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
 928                                 goto sctp_flush_out;
 929                         if (transport == asoc->peer.retran_path)
 930                                 goto retran;
 931
 932                         /* Switch transports & prepare the packet.  */
 933
 934                         transport = asoc->peer.retran_path;
 935
 936                         if (list_empty(&transport->send_ready)) {
 937                                 list_add_tail(&transport->send_ready,
 938                                               &transport_list);
 939                         }
 940
 941                         packet = &transport->packet;
 942                         sctp_packet_config(packet, vtag,
 943                                            asoc->peer.ecn_capable);
 944                 retran:
 945                         error = sctp_outq_flush_rtx(q, packet,
 946                                                     rtx_timeout, &start_timer);
 947
 948                         if (start_timer)
 949                                 sctp_transport_reset_timers(transport);
 950
 951                         /* This can happen on COOKIE-ECHO resend.  Only
 952                          * one chunk can get bundled with a COOKIE-ECHO.
 953                          */
 954                         if (packet->has_cookie_echo)
 955                                 goto sctp_flush_out;
 956
 957                         /* Don't send new data if there is still data
 958                          * waiting to retransmit.
 959                          */
 960                         if (!list_empty(&q->retransmit))
 961                                 goto sctp_flush_out;
 962                 }
 963
 964                 /* Apply Max.Burst limitation to the current transport in
 965                  * case it will be used for new data.  We are going to
 966                  * rest it before we return, but we want to apply the limit
 967                  * to the currently queued data.
 968                  */
 969                 if (transport)
 970                         sctp_transport_burst_limited(transport);
 971
 972                 /* Finally, transmit new packets.  */
 973                 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 974                         /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
 975                          * stream identifier.
 976                          */
 977                         if (chunk->sinfo.sinfo_stream >=
 978                             asoc->c.sinit_num_ostreams) {
 979
 980                                 /* Mark as failed send. */
 981                                 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
 982                                 sctp_chunk_free(chunk);
 983                                 continue;
 984                         }
 985
 986                         /* Has this chunk expired? */
 987                         if (sctp_chunk_abandoned(chunk)) {
 988                                 sctp_chunk_fail(chunk, 0);
 989                                 sctp_chunk_free(chunk);
 990                                 continue;
 991                         }
 992
 993                         /* If there is a specified transport, use it.
 994                          * Otherwise, we want to use the active path.
 995                          */
 996                         new_transport = chunk->transport;
 997                         if (!new_transport ||
 998                             ((new_transport->state == SCTP_INACTIVE) ||
 999                              (new_transport->state == SCTP_UNCONFIRMED) ||
1000                              (new_transport->state == SCTP_PF)))
1001                                 new_transport = asoc->peer.active_path;
1002                         if (new_transport->state == SCTP_UNCONFIRMED)
1003                                 continue;
1004
1005                         /* Change packets if necessary.  */
1006                         if (new_transport != transport) {
1007                                 transport = new_transport;
1008
1009                                 /* Schedule to have this transport's
1010                                  * packet flushed.
1011                                  */
1012                                 if (list_empty(&transport->send_ready)) {
1013                                         list_add_tail(&transport->send_ready,
1014                                                       &transport_list);
1015                                 }
1016
1017                                 packet = &transport->packet;
1018                                 sctp_packet_config(packet, vtag,
1019                                                    asoc->peer.ecn_capable);
1020                                 /* We've switched transports, so apply the
1021                                  * Burst limit to the new transport.
1022                                  */
1023                                 sctp_transport_burst_limited(transport);
1024                         }
1025
1026                         SCTP_DEBUG_PRINTK("sctp_outq_flush(%p, %p[%s]), ",
1027                                           q, chunk,
1028                                           chunk && chunk->chunk_hdr ?
1029                                           sctp_cname(SCTP_ST_CHUNK(
1030                                                   chunk->chunk_hdr->type))
1031                                           : "Illegal Chunk");
1032
1033                         SCTP_DEBUG_PRINTK("TX TSN 0x%x skb->head "
1034                                         "%p skb->users %d.\n",
1035                                         ntohl(chunk->subh.data_hdr->tsn),
1036                                         chunk->skb ?chunk->skb->head : NULL,
1037                                         chunk->skb ?
1038                                         atomic_read(&chunk->skb->users) : -1);
1039
1040                         /* Add the chunk to the packet.  */
1041                         status = sctp_packet_transmit_chunk(packet, chunk, 0);
1042
1043                         switch (status) {
1044                         case SCTP_XMIT_PMTU_FULL:
1045                         case SCTP_XMIT_RWND_FULL:
1046                         case SCTP_XMIT_NAGLE_DELAY:
1047                                 /* We could not append this chunk, so put
1048                                  * the chunk back on the output queue.
1049                                  */
1050                                 SCTP_DEBUG_PRINTK("sctp_outq_flush: could "
1051                                         "not transmit TSN: 0x%x, status: %d\n",
1052                                         ntohl(chunk->subh.data_hdr->tsn),
1053                                         status);
1054                                 sctp_outq_head_data(q, chunk);
1055                                 goto sctp_flush_out;
1056                                 break;
1057
1058                         case SCTP_XMIT_OK:
1059                                 /* The sender is in the SHUTDOWN-PENDING state,
1060                                  * The sender MAY set the I-bit in the DATA
1061                                  * chunk header.
1062                                  */
1063                                 if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1064                                         chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1065                                 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
1066                                         asoc->stats.ouodchunks++;
1067                                 else
1068                                         asoc->stats.oodchunks++;
1069
1070                                 break;
1071
1072                         default:
1073                                 BUG();
1074                         }
1075
1076                         /* BUG: We assume that the sctp_packet_transmit()
1077                          * call below will succeed all the time and add the
1078                          * chunk to the transmitted list and restart the
1079                          * timers.
1080                          * It is possible that the call can fail under OOM
1081                          * conditions.
1082                          *
1083                          * Is this really a problem?  Won't this behave
1084                          * like a lost TSN?
1085                          */
1086                         list_add_tail(&chunk->transmitted_list,
1087                                       &transport->transmitted);
1088
1089                         sctp_transport_reset_timers(transport);
1090
1091                         q->empty = 0;
1092
1093                         /* Only let one DATA chunk get bundled with a
1094                          * COOKIE-ECHO chunk.
1095                          */
1096                         if (packet->has_cookie_echo)
1097                                 goto sctp_flush_out;
1098                 }
1099                 break;
1100
1101         default:
1102                 /* Do nothing.  */
1103                 break;
1104         }
1105
1106 sctp_flush_out:
1107
1108         /* Before returning, examine all the transports touched in
1109          * this call.  Right now, we bluntly force clear all the
1110          * transports.  Things might change after we implement Nagle.
1111          * But such an examination is still required.
1112          *
1113          * --xguo
1114          */
1115         while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
1116                 struct sctp_transport *t = list_entry(ltransport,
1117                                                       struct sctp_transport,
1118                                                       send_ready);
1119                 packet = &t->packet;
1120                 if (!sctp_packet_empty(packet))
1121                         error = sctp_packet_transmit(packet);
1122
1123                 /* Clear the burst limited state, if any */
1124                 sctp_transport_burst_reset(t);
1125         }
1126
1127         return error;
1128 }
1129
1130 /* Update unack_data based on the incoming SACK chunk */
1131 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1132                                         struct sctp_sackhdr *sack)
1133 {
1134         sctp_sack_variable_t *frags;
1135         __u16 unack_data;
1136         int i;
1137
1138         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1139
1140         frags = sack->variable;
1141         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1142                 unack_data -= ((ntohs(frags[i].gab.end) -
1143                                 ntohs(frags[i].gab.start) + 1));
1144         }
1145
1146         assoc->unack_data = unack_data;
1147 }
1148
1149 /* This is where we REALLY process a SACK.
1150  *
1151  * Process the SACK against the outqueue.  Mostly, this just frees
1152  * things off the transmitted queue.
1153  */
1154 int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1155 {
1156         struct sctp_association *asoc = q->asoc;
1157         struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1158         struct sctp_transport *transport;
1159         struct sctp_chunk *tchunk = NULL;
1160         struct list_head *lchunk, *transport_list, *temp;
1161         sctp_sack_variable_t *frags = sack->variable;
1162         __u32 sack_ctsn, ctsn, tsn;
1163         __u32 highest_tsn, highest_new_tsn;
1164         __u32 sack_a_rwnd;
1165         unsigned int outstanding;
1166         struct sctp_transport *primary = asoc->peer.primary_path;
1167         int count_of_newacks = 0;
1168         int gap_ack_blocks;
1169         u8 accum_moved = 0;
1170
1171         /* Grab the association's destination address list. */
1172         transport_list = &asoc->peer.transport_addr_list;
1173
1174         sack_ctsn = ntohl(sack->cum_tsn_ack);
1175         gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1176         asoc->stats.gapcnt += gap_ack_blocks;
1177         /*
1178          * SFR-CACC algorithm:
1179          * On receipt of a SACK the sender SHOULD execute the
1180          * following statements.
1181          *
1182          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1183          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1184          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1185          * all destinations.
1186          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1187          * is set the receiver of the SACK MUST take the following actions:
1188          *
1189          * A) Initialize the cacc_saw_newack to 0 for all destination
1190          * addresses.
1191          *
1192          * Only bother if changeover_active is set. Otherwise, this is
1193          * totally suboptimal to do on every SACK.
1194          */
1195         if (primary->cacc.changeover_active) {
1196                 u8 clear_cycling = 0;
1197
1198                 if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1199                         primary->cacc.changeover_active = 0;
1200                         clear_cycling = 1;
1201                 }
1202
1203                 if (clear_cycling || gap_ack_blocks) {
1204                         list_for_each_entry(transport, transport_list,
1205                                         transports) {
1206                                 if (clear_cycling)
1207                                         transport->cacc.cycling_changeover = 0;
1208                                 if (gap_ack_blocks)
1209                                         transport->cacc.cacc_saw_newack = 0;
1210                         }
1211                 }
1212         }
1213
1214         /* Get the highest TSN in the sack. */
1215         highest_tsn = sack_ctsn;
1216         if (gap_ack_blocks)
1217                 highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1218
1219         if (TSN_lt(asoc->highest_sacked, highest_tsn))
1220                 asoc->highest_sacked = highest_tsn;
1221
1222         highest_new_tsn = sack_ctsn;
1223
1224         /* Run through the retransmit queue.  Credit bytes received
1225          * and free those chunks that we can.
1226          */
1227         sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1228
1229         /* Run through the transmitted queue.
1230          * Credit bytes received and free those chunks which we can.
1231          *
1232          * This is a MASSIVE candidate for optimization.
1233          */
1234         list_for_each_entry(transport, transport_list, transports) {
1235                 sctp_check_transmitted(q, &transport->transmitted,
1236                                        transport, &chunk->source, sack,
1237                                        &highest_new_tsn);
1238                 /*
1239                  * SFR-CACC algorithm:
1240                  * C) Let count_of_newacks be the number of
1241                  * destinations for which cacc_saw_newack is set.
1242                  */
1243                 if (transport->cacc.cacc_saw_newack)
1244                         count_of_newacks ++;
1245         }
1246
1247         /* Move the Cumulative TSN Ack Point if appropriate.  */
1248         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1249                 asoc->ctsn_ack_point = sack_ctsn;
1250                 accum_moved = 1;
1251         }
1252
1253         if (gap_ack_blocks) {
1254
1255                 if (asoc->fast_recovery && accum_moved)
1256                         highest_new_tsn = highest_tsn;
1257
1258                 list_for_each_entry(transport, transport_list, transports)
1259                         sctp_mark_missing(q, &transport->transmitted, transport,
1260                                           highest_new_tsn, count_of_newacks);
1261         }
1262
1263         /* Update unack_data field in the assoc. */
1264         sctp_sack_update_unack_data(asoc, sack);
1265
1266         ctsn = asoc->ctsn_ack_point;
1267
1268         /* Throw away stuff rotting on the sack queue.  */
1269         list_for_each_safe(lchunk, temp, &q->sacked) {
1270                 tchunk = list_entry(lchunk, struct sctp_chunk,
1271                                     transmitted_list);
1272                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1273                 if (TSN_lte(tsn, ctsn)) {
1274                         list_del_init(&tchunk->transmitted_list);
1275                         sctp_chunk_free(tchunk);
1276                 }
1277         }
1278
1279         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1280          *     number of bytes still outstanding after processing the
1281          *     Cumulative TSN Ack and the Gap Ack Blocks.
1282          */
1283
1284         sack_a_rwnd = ntohl(sack->a_rwnd);
1285         outstanding = q->outstanding_bytes;
1286
1287         if (outstanding < sack_a_rwnd)
1288                 sack_a_rwnd -= outstanding;
1289         else
1290                 sack_a_rwnd = 0;
1291
1292         asoc->peer.rwnd = sack_a_rwnd;
1293
1294         sctp_generate_fwdtsn(q, sack_ctsn);
1295
1296         SCTP_DEBUG_PRINTK("%s: sack Cumulative TSN Ack is 0x%x.\n",
1297                           __func__, sack_ctsn);
1298         SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
1299                           "%p is 0x%x. Adv peer ack point: 0x%x\n",
1300                           __func__, asoc, ctsn, asoc->adv_peer_ack_point);
1301
1302         /* See if all chunks are acked.
1303          * Make sure the empty queue handler will get run later.
1304          */
1305         q->empty = (list_empty(&q->out_chunk_list) &&
1306                     list_empty(&q->retransmit));
1307         if (!q->empty)
1308                 goto finish;
1309
1310         list_for_each_entry(transport, transport_list, transports) {
1311                 q->empty = q->empty && list_empty(&transport->transmitted);
1312                 if (!q->empty)
1313                         goto finish;
1314         }
1315
1316         SCTP_DEBUG_PRINTK("sack queue is empty.\n");
1317 finish:
1318         return q->empty;
1319 }
1320
1321 /* Is the outqueue empty?  */
1322 int sctp_outq_is_empty(const struct sctp_outq *q)
1323 {
1324         return q->empty;
1325 }
1326
1327 /********************************************************************
1328  * 2nd Level Abstractions
1329  ********************************************************************/
1330
1331 /* Go through a transport's transmitted list or the association's retransmit
1332  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1333  * The retransmit list will not have an associated transport.
1334  *
1335  * I added coherent debug information output.   --xguo
1336  *
1337  * Instead of printing 'sacked' or 'kept' for each TSN on the
1338  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1339  * KEPT TSN6-TSN7, etc.
1340  */
1341 static void sctp_check_transmitted(struct sctp_outq *q,
1342                                    struct list_head *transmitted_queue,
1343                                    struct sctp_transport *transport,
1344                                    union sctp_addr *saddr,
1345                                    struct sctp_sackhdr *sack,
1346                                    __u32 *highest_new_tsn_in_sack)
1347 {
1348         struct list_head *lchunk;
1349         struct sctp_chunk *tchunk;
1350         struct list_head tlist;
1351         __u32 tsn;
1352         __u32 sack_ctsn;
1353         __u32 rtt;
1354         __u8 restart_timer = 0;
1355         int bytes_acked = 0;
1356         int migrate_bytes = 0;
1357
1358         /* These state variables are for coherent debug output. --xguo */
1359
1360 #if SCTP_DEBUG
1361         __u32 dbg_ack_tsn = 0;  /* An ACKed TSN range starts here... */
1362         __u32 dbg_last_ack_tsn = 0;  /* ...and finishes here.        */
1363         __u32 dbg_kept_tsn = 0; /* An un-ACKed range starts here...  */
1364         __u32 dbg_last_kept_tsn = 0; /* ...and finishes here.        */
1365
1366         /* 0 : The last TSN was ACKed.
1367          * 1 : The last TSN was NOT ACKed (i.e. KEPT).
1368          * -1: We need to initialize.
1369          */
1370         int dbg_prt_state = -1;
1371 #endif /* SCTP_DEBUG */
1372
1373         sack_ctsn = ntohl(sack->cum_tsn_ack);
1374
1375         INIT_LIST_HEAD(&tlist);
1376
1377         /* The while loop will skip empty transmitted queues. */
1378         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1379                 tchunk = list_entry(lchunk, struct sctp_chunk,
1380                                     transmitted_list);
1381
1382                 if (sctp_chunk_abandoned(tchunk)) {
1383                         /* Move the chunk to abandoned list. */
1384                         sctp_insert_list(&q->abandoned, lchunk);
1385
1386                         /* If this chunk has not been acked, stop
1387                          * considering it as 'outstanding'.
1388                          */
1389                         if (!tchunk->tsn_gap_acked) {
1390                                 if (tchunk->transport)
1391                                         tchunk->transport->flight_size -=
1392                                                         sctp_data_size(tchunk);
1393                                 q->outstanding_bytes -= sctp_data_size(tchunk);
1394                         }
1395                         continue;
1396                 }
1397
1398                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1399                 if (sctp_acked(sack, tsn)) {
1400                         /* If this queue is the retransmit queue, the
1401                          * retransmit timer has already reclaimed
1402                          * the outstanding bytes for this chunk, so only
1403                          * count bytes associated with a transport.
1404                          */
1405                         if (transport) {
1406                                 /* If this chunk is being used for RTT
1407                                  * measurement, calculate the RTT and update
1408                                  * the RTO using this value.
1409                                  *
1410                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1411                                  * MUST NOT be made using packets that were
1412                                  * retransmitted (and thus for which it is
1413                                  * ambiguous whether the reply was for the
1414                                  * first instance of the packet or a later
1415                                  * instance).
1416                                  */
1417                                 if (!tchunk->tsn_gap_acked &&
1418                                     tchunk->rtt_in_progress) {
1419                                         tchunk->rtt_in_progress = 0;
1420                                         rtt = jiffies - tchunk->sent_at;
1421                                         sctp_transport_update_rto(transport,
1422                                                                   rtt);
1423                                 }
1424                         }
1425
1426                         /* If the chunk hasn't been marked as ACKED,
1427                          * mark it and account bytes_acked if the
1428                          * chunk had a valid transport (it will not
1429                          * have a transport if ASCONF had deleted it
1430                          * while DATA was outstanding).
1431                          */
1432                         if (!tchunk->tsn_gap_acked) {
1433                                 tchunk->tsn_gap_acked = 1;
1434                                 *highest_new_tsn_in_sack = tsn;
1435                                 bytes_acked += sctp_data_size(tchunk);
1436                                 if (!tchunk->transport)
1437                                         migrate_bytes += sctp_data_size(tchunk);
1438                         }
1439
1440                         if (TSN_lte(tsn, sack_ctsn)) {
1441                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1442                                  *
1443                                  * R3) Whenever a SACK is received
1444                                  * that acknowledges the DATA chunk
1445                                  * with the earliest outstanding TSN
1446                                  * for that address, restart T3-rtx
1447                                  * timer for that address with its
1448                                  * current RTO.
1449                                  */
1450                                 restart_timer = 1;
1451
1452                                 if (!tchunk->tsn_gap_acked) {
1453                                         /*
1454                                          * SFR-CACC algorithm:
1455                                          * 2) If the SACK contains gap acks
1456                                          * and the flag CHANGEOVER_ACTIVE is
1457                                          * set the receiver of the SACK MUST
1458                                          * take the following action:
1459                                          *
1460                                          * B) For each TSN t being acked that
1461                                          * has not been acked in any SACK so
1462                                          * far, set cacc_saw_newack to 1 for
1463                                          * the destination that the TSN was
1464                                          * sent to.
1465                                          */
1466                                         if (transport &&
1467                                             sack->num_gap_ack_blocks &&
1468                                             q->asoc->peer.primary_path->cacc.
1469                                             changeover_active)
1470                                                 transport->cacc.cacc_saw_newack
1471                                                         = 1;
1472                                 }
1473
1474                                 list_add_tail(&tchunk->transmitted_list,
1475                                               &q->sacked);
1476                         } else {
1477                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1478                                  * M2) Each time a SACK arrives reporting
1479                                  * 'Stray DATA chunk(s)' record the highest TSN
1480                                  * reported as newly acknowledged, call this
1481                                  * value 'HighestTSNinSack'. A newly
1482                                  * acknowledged DATA chunk is one not
1483                                  * previously acknowledged in a SACK.
1484                                  *
1485                                  * When the SCTP sender of data receives a SACK
1486                                  * chunk that acknowledges, for the first time,
1487                                  * the receipt of a DATA chunk, all the still
1488                                  * unacknowledged DATA chunks whose TSN is
1489                                  * older than that newly acknowledged DATA
1490                                  * chunk, are qualified as 'Stray DATA chunks'.
1491                                  */
1492                                 list_add_tail(lchunk, &tlist);
1493                         }
1494
1495 #if SCTP_DEBUG
1496                         switch (dbg_prt_state) {
1497                         case 0: /* last TSN was ACKed */
1498                                 if (dbg_last_ack_tsn + 1 == tsn) {
1499                                         /* This TSN belongs to the
1500                                          * current ACK range.
1501                                          */
1502                                         break;
1503                                 }
1504
1505                                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1506                                         /* Display the end of the
1507                                          * current range.
1508                                          */
1509                                         SCTP_DEBUG_PRINTK_CONT("-%08x",
1510                                                                dbg_last_ack_tsn);
1511                                 }
1512
1513                                 /* Start a new range.  */
1514                                 SCTP_DEBUG_PRINTK_CONT(",%08x", tsn);
1515                                 dbg_ack_tsn = tsn;
1516                                 break;
1517
1518                         case 1: /* The last TSN was NOT ACKed. */
1519                                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1520                                         /* Display the end of current range. */
1521                                         SCTP_DEBUG_PRINTK_CONT("-%08x",
1522                                                                dbg_last_kept_tsn);
1523                                 }
1524
1525                                 SCTP_DEBUG_PRINTK_CONT("\n");
1526
1527                                 /* FALL THROUGH... */
1528                         default:
1529                                 /* This is the first-ever TSN we examined.  */
1530                                 /* Start a new range of ACK-ed TSNs.  */
1531                                 SCTP_DEBUG_PRINTK("ACKed: %08x", tsn);
1532                                 dbg_prt_state = 0;
1533                                 dbg_ack_tsn = tsn;
1534                         }
1535
1536                         dbg_last_ack_tsn = tsn;
1537 #endif /* SCTP_DEBUG */
1538
1539                 } else {
1540                         if (tchunk->tsn_gap_acked) {
1541                                 SCTP_DEBUG_PRINTK("%s: Receiver reneged on "
1542                                                   "data TSN: 0x%x\n",
1543                                                   __func__,
1544                                                   tsn);
1545                                 tchunk->tsn_gap_acked = 0;
1546
1547                                 if (tchunk->transport)
1548                                         bytes_acked -= sctp_data_size(tchunk);
1549
1550                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1551                                  *
1552                                  * R4) Whenever a SACK is received missing a
1553                                  * TSN that was previously acknowledged via a
1554                                  * Gap Ack Block, start T3-rtx for the
1555                                  * destination address to which the DATA
1556                                  * chunk was originally
1557                                  * transmitted if it is not already running.
1558                                  */
1559                                 restart_timer = 1;
1560                         }
1561
1562                         list_add_tail(lchunk, &tlist);
1563
1564 #if SCTP_DEBUG
1565                         /* See the above comments on ACK-ed TSNs. */
1566                         switch (dbg_prt_state) {
1567                         case 1:
1568                                 if (dbg_last_kept_tsn + 1 == tsn)
1569                                         break;
1570
1571                                 if (dbg_last_kept_tsn != dbg_kept_tsn)
1572                                         SCTP_DEBUG_PRINTK_CONT("-%08x",
1573                                                                dbg_last_kept_tsn);
1574
1575                                 SCTP_DEBUG_PRINTK_CONT(",%08x", tsn);
1576                                 dbg_kept_tsn = tsn;
1577                                 break;
1578
1579                         case 0:
1580                                 if (dbg_last_ack_tsn != dbg_ack_tsn)
1581                                         SCTP_DEBUG_PRINTK_CONT("-%08x",
1582                                                                dbg_last_ack_tsn);
1583                                 SCTP_DEBUG_PRINTK_CONT("\n");
1584
1585                                 /* FALL THROUGH... */
1586                         default:
1587                                 SCTP_DEBUG_PRINTK("KEPT: %08x",tsn);
1588                                 dbg_prt_state = 1;
1589                                 dbg_kept_tsn = tsn;
1590                         }
1591
1592                         dbg_last_kept_tsn = tsn;
1593 #endif /* SCTP_DEBUG */
1594                 }
1595         }
1596
1597 #if SCTP_DEBUG
1598         /* Finish off the last range, displaying its ending TSN.  */
1599         switch (dbg_prt_state) {
1600         case 0:
1601                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1602                         SCTP_DEBUG_PRINTK_CONT("-%08x\n", dbg_last_ack_tsn);
1603                 } else {
1604                         SCTP_DEBUG_PRINTK_CONT("\n");
1605                 }
1606         break;
1607
1608         case 1:
1609                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1610                         SCTP_DEBUG_PRINTK_CONT("-%08x\n", dbg_last_kept_tsn);
1611                 } else {
1612                         SCTP_DEBUG_PRINTK_CONT("\n");
1613                 }
1614         }
1615 #endif /* SCTP_DEBUG */
1616         if (transport) {
1617                 if (bytes_acked) {
1618                         struct sctp_association *asoc = transport->asoc;
1619
1620                         /* We may have counted DATA that was migrated
1621                          * to this transport due to DEL-IP operation.
1622                          * Subtract those bytes, since the were never
1623                          * send on this transport and shouldn't be
1624                          * credited to this transport.
1625                          */
1626                         bytes_acked -= migrate_bytes;
1627
1628                         /* 8.2. When an outstanding TSN is acknowledged,
1629                          * the endpoint shall clear the error counter of
1630                          * the destination transport address to which the
1631                          * DATA chunk was last sent.
1632                          * The association's overall error counter is
1633                          * also cleared.
1634                          */
1635                         transport->error_count = 0;
1636                         transport->asoc->overall_error_count = 0;
1637
1638                         /*
1639                          * While in SHUTDOWN PENDING, we may have started
1640                          * the T5 shutdown guard timer after reaching the
1641                          * retransmission limit. Stop that timer as soon
1642                          * as the receiver acknowledged any data.
1643                          */
1644                         if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1645                             del_timer(&asoc->timers
1646                                 [SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1647                                         sctp_association_put(asoc);
1648
1649                         /* Mark the destination transport address as
1650                          * active if it is not so marked.
1651                          */
1652                         if ((transport->state == SCTP_INACTIVE ||
1653                              transport->state == SCTP_UNCONFIRMED) &&
1654                             sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1655                                 sctp_assoc_control_transport(
1656                                         transport->asoc,
1657                                         transport,
1658                                         SCTP_TRANSPORT_UP,
1659                                         SCTP_RECEIVED_SACK);
1660                         }
1661
1662                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1663                                                   bytes_acked);
1664
1665                         transport->flight_size -= bytes_acked;
1666                         if (transport->flight_size == 0)
1667                                 transport->partial_bytes_acked = 0;
1668                         q->outstanding_bytes -= bytes_acked + migrate_bytes;
1669                 } else {
1670                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1671                          * When a sender is doing zero window probing, it
1672                          * should not timeout the association if it continues
1673                          * to receive new packets from the receiver. The
1674                          * reason is that the receiver MAY keep its window
1675                          * closed for an indefinite time.
1676                          * A sender is doing zero window probing when the
1677                          * receiver's advertised window is zero, and there is
1678                          * only one data chunk in flight to the receiver.
1679                          *
1680                          * Allow the association to timeout while in SHUTDOWN
1681                          * PENDING or SHUTDOWN RECEIVED in case the receiver
1682                          * stays in zero window mode forever.
1683                          */
1684                         if (!q->asoc->peer.rwnd &&
1685                             !list_empty(&tlist) &&
1686                             (sack_ctsn+2 == q->asoc->next_tsn) &&
1687                             q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1688                                 SCTP_DEBUG_PRINTK("%s: SACK received for zero "
1689                                                   "window probe: %u\n",
1690                                                   __func__, sack_ctsn);
1691                                 q->asoc->overall_error_count = 0;
1692                                 transport->error_count = 0;
1693                         }
1694                 }
1695
1696                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1697                  *
1698                  * R2) Whenever all outstanding data sent to an address have
1699                  * been acknowledged, turn off the T3-rtx timer of that
1700                  * address.
1701                  */
1702                 if (!transport->flight_size) {
1703                         if (del_timer(&transport->T3_rtx_timer))
1704                                 sctp_transport_put(transport);
1705                 } else if (restart_timer) {
1706                         if (!mod_timer(&transport->T3_rtx_timer,
1707                                        jiffies + transport->rto))
1708                                 sctp_transport_hold(transport);
1709                 }
1710         }
1711
1712         list_splice(&tlist, transmitted_queue);
1713 }
1714
1715 /* Mark chunks as missing and consequently may get retransmitted. */
1716 static void sctp_mark_missing(struct sctp_outq *q,
1717                               struct list_head *transmitted_queue,
1718                               struct sctp_transport *transport,
1719                               __u32 highest_new_tsn_in_sack,
1720                               int count_of_newacks)
1721 {
1722         struct sctp_chunk *chunk;
1723         __u32 tsn;
1724         char do_fast_retransmit = 0;
1725         struct sctp_association *asoc = q->asoc;
1726         struct sctp_transport *primary = asoc->peer.primary_path;
1727
1728         list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1729
1730                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1731
1732                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1733                  * 'Unacknowledged TSN's', if the TSN number of an
1734                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1735                  * value, increment the 'TSN.Missing.Report' count on that
1736                  * chunk if it has NOT been fast retransmitted or marked for
1737                  * fast retransmit already.
1738                  */
1739                 if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1740                     !chunk->tsn_gap_acked &&
1741                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1742
1743                         /* SFR-CACC may require us to skip marking
1744                          * this chunk as missing.
1745                          */
1746                         if (!transport || !sctp_cacc_skip(primary,
1747                                                 chunk->transport,
1748                                                 count_of_newacks, tsn)) {
1749                                 chunk->tsn_missing_report++;
1750
1751                                 SCTP_DEBUG_PRINTK(
1752                                         "%s: TSN 0x%x missing counter: %d\n",
1753                                         __func__, tsn,
1754                                         chunk->tsn_missing_report);
1755                         }
1756                 }
1757                 /*
1758                  * M4) If any DATA chunk is found to have a
1759                  * 'TSN.Missing.Report'
1760                  * value larger than or equal to 3, mark that chunk for
1761                  * retransmission and start the fast retransmit procedure.
1762                  */
1763
1764                 if (chunk->tsn_missing_report >= 3) {
1765                         chunk->fast_retransmit = SCTP_NEED_FRTX;
1766                         do_fast_retransmit = 1;
1767                 }
1768         }
1769
1770         if (transport) {
1771                 if (do_fast_retransmit)
1772                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1773
1774                 SCTP_DEBUG_PRINTK("%s: transport: %p, cwnd: %d, "
1775                                   "ssthresh: %d, flight_size: %d, pba: %d\n",
1776                                   __func__, transport, transport->cwnd,
1777                                   transport->ssthresh, transport->flight_size,
1778                                   transport->partial_bytes_acked);
1779         }
1780 }
1781
1782 /* Is the given TSN acked by this packet?  */
1783 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1784 {
1785         int i;
1786         sctp_sack_variable_t *frags;
1787         __u16 gap;
1788         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1789
1790         if (TSN_lte(tsn, ctsn))
1791                 goto pass;
1792
1793         /* 3.3.4 Selective Acknowledgement (SACK) (3):
1794          *
1795          * Gap Ack Blocks:
1796          *  These fields contain the Gap Ack Blocks. They are repeated
1797          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1798          *  defined in the Number of Gap Ack Blocks field. All DATA
1799          *  chunks with TSNs greater than or equal to (Cumulative TSN
1800          *  Ack + Gap Ack Block Start) and less than or equal to
1801          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1802          *  Block are assumed to have been received correctly.
1803          */
1804
1805         frags = sack->variable;
1806         gap = tsn - ctsn;
1807         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1808                 if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1809                     TSN_lte(gap, ntohs(frags[i].gab.end)))
1810                         goto pass;
1811         }
1812
1813         return 0;
1814 pass:
1815         return 1;
1816 }
1817
1818 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1819                                     int nskips, __be16 stream)
1820 {
1821         int i;
1822
1823         for (i = 0; i < nskips; i++) {
1824                 if (skiplist[i].stream == stream)
1825                         return i;
1826         }
1827         return i;
1828 }
1829
1830 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1831 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1832 {
1833         struct sctp_association *asoc = q->asoc;
1834         struct sctp_chunk *ftsn_chunk = NULL;
1835         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1836         int nskips = 0;
1837         int skip_pos = 0;
1838         __u32 tsn;
1839         struct sctp_chunk *chunk;
1840         struct list_head *lchunk, *temp;
1841
1842         if (!asoc->peer.prsctp_capable)
1843                 return;
1844
1845         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1846          * received SACK.
1847          *
1848          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1849          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1850          */
1851         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1852                 asoc->adv_peer_ack_point = ctsn;
1853
1854         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1855          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1856          * the chunk next in the out-queue space is marked as "abandoned" as
1857          * shown in the following example:
1858          *
1859          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1860          * and the Advanced.Peer.Ack.Point is updated to this value:
1861          *
1862          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1863          *   normal SACK processing           local advancement
1864          *                ...                           ...
1865          *   Adv.Ack.Pt-> 102 acked                     102 acked
1866          *                103 abandoned                 103 abandoned
1867          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1868          *                105                           105
1869          *                106 acked                     106 acked
1870          *                ...                           ...
1871          *
1872          * In this example, the data sender successfully advanced the
1873          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1874          */
1875         list_for_each_safe(lchunk, temp, &q->abandoned) {
1876                 chunk = list_entry(lchunk, struct sctp_chunk,
1877                                         transmitted_list);
1878                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1879
1880                 /* Remove any chunks in the abandoned queue that are acked by
1881                  * the ctsn.
1882                  */
1883                 if (TSN_lte(tsn, ctsn)) {
1884                         list_del_init(lchunk);
1885                         sctp_chunk_free(chunk);
1886                 } else {
1887                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1888                                 asoc->adv_peer_ack_point = tsn;
1889                                 if (chunk->chunk_hdr->flags &
1890                                          SCTP_DATA_UNORDERED)
1891                                         continue;
1892                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1893                                                 nskips,
1894                                                 chunk->subh.data_hdr->stream);
1895                                 ftsn_skip_arr[skip_pos].stream =
1896                                         chunk->subh.data_hdr->stream;
1897                                 ftsn_skip_arr[skip_pos].ssn =
1898                                          chunk->subh.data_hdr->ssn;
1899                                 if (skip_pos == nskips)
1900                                         nskips++;
1901                                 if (nskips == 10)
1902                                         break;
1903                         } else
1904                                 break;
1905                 }
1906         }
1907
1908         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1909          * is greater than the Cumulative TSN ACK carried in the received
1910          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1911          * chunk containing the latest value of the
1912          * "Advanced.Peer.Ack.Point".
1913          *
1914          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1915          * list each stream and sequence number in the forwarded TSN. This
1916          * information will enable the receiver to easily find any
1917          * stranded TSN's waiting on stream reorder queues. Each stream
1918          * SHOULD only be reported once; this means that if multiple
1919          * abandoned messages occur in the same stream then only the
1920          * highest abandoned stream sequence number is reported. If the
1921          * total size of the FORWARD TSN does NOT fit in a single MTU then
1922          * the sender of the FORWARD TSN SHOULD lower the
1923          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1924          * single MTU.
1925          */
1926         if (asoc->adv_peer_ack_point > ctsn)
1927                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1928                                               nskips, &ftsn_skip_arr[0]);
1929
1930         if (ftsn_chunk) {
1931                 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1932                 SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_OUTCTRLCHUNKS);
1933         }
1934 }