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, see
  26  * <http://www.gnu.org/licenses/>.
  27  *
  28  * Please send any bug reports or fixes you make to the
  29  * email address(es):
  30  *    lksctp developers <linux-sctp@vger.kernel.org>
  31  *
  32  * Written or modified by:
  33  *    La Monte H.P. Yarroll <piggy@acm.org>
  34  *    Karl Knutson          <karl@athena.chicago.il.us>
  35  *    Perry Melange         <pmelange@null.cc.uic.edu>
  36  *    Xingang Guo           <xingang.guo@intel.com>
  37  *    Hui Huang             <hui.huang@nokia.com>
  38  *    Sridhar Samudrala     <sri@us.ibm.com>
  39  *    Jon Grimm             <jgrimm@us.ibm.com>
  40  */
  41
  42 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  43
  44 #include <linux/types.h>
  45 #include <linux/list.h>   /* For struct list_head */
  46 #include <linux/socket.h>
  47 #include <linux/ip.h>
  48 #include <linux/slab.h>
  49 #include <net/sock.h>     /* For skb_set_owner_w */
  50
  51 #include <net/sctp/sctp.h>
  52 #include <net/sctp/sm.h>
  53 #include <net/sctp/stream_sched.h>
  54 #include <trace/events/sctp.h>
  55
  56 /* Declare internal functions here.  */
  57 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
  58 static void sctp_check_transmitted(struct sctp_outq *q,
  59                                    struct list_head *transmitted_queue,
  60                                    struct sctp_transport *transport,
  61                                    union sctp_addr *saddr,
  62                                    struct sctp_sackhdr *sack,
  63                                    __u32 *highest_new_tsn);
  64
  65 static void sctp_mark_missing(struct sctp_outq *q,
  66                               struct list_head *transmitted_queue,
  67                               struct sctp_transport *transport,
  68                               __u32 highest_new_tsn,
  69                               int count_of_newacks);
  70
  71 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp);
  72
  73 /* Add data to the front of the queue. */
  74 static inline void sctp_outq_head_data(struct sctp_outq *q,
  75                                        struct sctp_chunk *ch)
  76 {
  77         struct sctp_stream_out_ext *oute;
  78         __u16 stream;
  79
  80         list_add(&ch->list, &q->out_chunk_list);
  81         q->out_qlen += ch->skb->len;
  82
  83         stream = sctp_chunk_stream_no(ch);
  84         oute = SCTP_SO(&q->asoc->stream, stream)->ext;
  85         list_add(&ch->stream_list, &oute->outq);
  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         return q->sched->dequeue(q);
  92 }
  93
  94 /* Add data chunk to the end of the queue. */
  95 static inline void sctp_outq_tail_data(struct sctp_outq *q,
  96                                        struct sctp_chunk *ch)
  97 {
  98         struct sctp_stream_out_ext *oute;
  99         __u16 stream;
 100
 101         list_add_tail(&ch->list, &q->out_chunk_list);
 102         q->out_qlen += ch->skb->len;
 103
 104         stream = sctp_chunk_stream_no(ch);
 105         oute = SCTP_SO(&q->asoc->stream, stream)->ext;
 106         list_add_tail(&ch->stream_list, &oute->outq);
 107 }
 108
 109 /*
 110  * SFR-CACC algorithm:
 111  * D) If count_of_newacks is greater than or equal to 2
 112  * and t was not sent to the current primary then the
 113  * sender MUST NOT increment missing report count for t.
 114  */
 115 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
 116                                        struct sctp_transport *transport,
 117                                        int count_of_newacks)
 118 {
 119         if (count_of_newacks >= 2 && transport != primary)
 120                 return 1;
 121         return 0;
 122 }
 123
 124 /*
 125  * SFR-CACC algorithm:
 126  * F) If count_of_newacks is less than 2, let d be the
 127  * destination to which t was sent. If cacc_saw_newack
 128  * is 0 for destination d, then the sender MUST NOT
 129  * increment missing report count for t.
 130  */
 131 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
 132                                        int count_of_newacks)
 133 {
 134         if (count_of_newacks < 2 &&
 135                         (transport && !transport->cacc.cacc_saw_newack))
 136                 return 1;
 137         return 0;
 138 }
 139
 140 /*
 141  * SFR-CACC algorithm:
 142  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
 143  * execute steps C, D, F.
 144  *
 145  * C has been implemented in sctp_outq_sack
 146  */
 147 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
 148                                      struct sctp_transport *transport,
 149                                      int count_of_newacks)
 150 {
 151         if (!primary->cacc.cycling_changeover) {
 152                 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
 153                         return 1;
 154                 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
 155                         return 1;
 156                 return 0;
 157         }
 158         return 0;
 159 }
 160
 161 /*
 162  * SFR-CACC algorithm:
 163  * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
 164  * than next_tsn_at_change of the current primary, then
 165  * the sender MUST NOT increment missing report count
 166  * for t.
 167  */
 168 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
 169 {
 170         if (primary->cacc.cycling_changeover &&
 171             TSN_lt(tsn, primary->cacc.next_tsn_at_change))
 172                 return 1;
 173         return 0;
 174 }
 175
 176 /*
 177  * SFR-CACC algorithm:
 178  * 3) If the missing report count for TSN t is to be
 179  * incremented according to [RFC2960] and
 180  * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
 181  * then the sender MUST further execute steps 3.1 and
 182  * 3.2 to determine if the missing report count for
 183  * TSN t SHOULD NOT be incremented.
 184  *
 185  * 3.3) If 3.1 and 3.2 do not dictate that the missing
 186  * report count for t should not be incremented, then
 187  * the sender SHOULD increment missing report count for
 188  * t (according to [RFC2960] and [SCTP_STEWART_2002]).
 189  */
 190 static inline int sctp_cacc_skip(struct sctp_transport *primary,
 191                                  struct sctp_transport *transport,
 192                                  int count_of_newacks,
 193                                  __u32 tsn)
 194 {
 195         if (primary->cacc.changeover_active &&
 196             (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
 197              sctp_cacc_skip_3_2(primary, tsn)))
 198                 return 1;
 199         return 0;
 200 }
 201
 202 /* Initialize an existing sctp_outq.  This does the boring stuff.
 203  * You still need to define handlers if you really want to DO
 204  * something with this structure...
 205  */
 206 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
 207 {
 208         memset(q, 0, sizeof(struct sctp_outq));
 209
 210         q->asoc = asoc;
 211         INIT_LIST_HEAD(&q->out_chunk_list);
 212         INIT_LIST_HEAD(&q->control_chunk_list);
 213         INIT_LIST_HEAD(&q->retransmit);
 214         INIT_LIST_HEAD(&q->sacked);
 215         INIT_LIST_HEAD(&q->abandoned);
 216         sctp_sched_set_sched(asoc, SCTP_SS_DEFAULT);
 217 }
 218
 219 /* Free the outqueue structure and any related pending chunks.
 220  */
 221 static void __sctp_outq_teardown(struct sctp_outq *q)
 222 {
 223         struct sctp_transport *transport;
 224         struct list_head *lchunk, *temp;
 225         struct sctp_chunk *chunk, *tmp;
 226
 227         /* Throw away unacknowledged chunks. */
 228         list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
 229                         transports) {
 230                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
 231                         chunk = list_entry(lchunk, struct sctp_chunk,
 232                                            transmitted_list);
 233                         /* Mark as part of a failed message. */
 234                         sctp_chunk_fail(chunk, q->error);
 235                         sctp_chunk_free(chunk);
 236                 }
 237         }
 238
 239         /* Throw away chunks that have been gap ACKed.  */
 240         list_for_each_safe(lchunk, temp, &q->sacked) {
 241                 list_del_init(lchunk);
 242                 chunk = list_entry(lchunk, struct sctp_chunk,
 243                                    transmitted_list);
 244                 sctp_chunk_fail(chunk, q->error);
 245                 sctp_chunk_free(chunk);
 246         }
 247
 248         /* Throw away any chunks in the retransmit queue. */
 249         list_for_each_safe(lchunk, temp, &q->retransmit) {
 250                 list_del_init(lchunk);
 251                 chunk = list_entry(lchunk, struct sctp_chunk,
 252                                    transmitted_list);
 253                 sctp_chunk_fail(chunk, q->error);
 254                 sctp_chunk_free(chunk);
 255         }
 256
 257         /* Throw away any chunks that are in the abandoned queue. */
 258         list_for_each_safe(lchunk, temp, &q->abandoned) {
 259                 list_del_init(lchunk);
 260                 chunk = list_entry(lchunk, struct sctp_chunk,
 261                                    transmitted_list);
 262                 sctp_chunk_fail(chunk, q->error);
 263                 sctp_chunk_free(chunk);
 264         }
 265
 266         /* Throw away any leftover data chunks. */
 267         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 268                 sctp_sched_dequeue_done(q, chunk);
 269
 270                 /* Mark as send failure. */
 271                 sctp_chunk_fail(chunk, q->error);
 272                 sctp_chunk_free(chunk);
 273         }
 274
 275         /* Throw away any leftover control chunks. */
 276         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 277                 list_del_init(&chunk->list);
 278                 sctp_chunk_free(chunk);
 279         }
 280 }
 281
 282 void sctp_outq_teardown(struct sctp_outq *q)
 283 {
 284         __sctp_outq_teardown(q);
 285         sctp_outq_init(q->asoc, q);
 286 }
 287
 288 /* Free the outqueue structure and any related pending chunks.  */
 289 void sctp_outq_free(struct sctp_outq *q)
 290 {
 291         /* Throw away leftover chunks. */
 292         __sctp_outq_teardown(q);
 293 }
 294
 295 /* Put a new chunk in an sctp_outq.  */
 296 void sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk, gfp_t gfp)
 297 {
 298         struct net *net = sock_net(q->asoc->base.sk);
 299
 300         pr_debug("%s: outq:%p, chunk:%p[%s]\n", __func__, q, chunk,
 301                  chunk && chunk->chunk_hdr ?
 302                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
 303                  "illegal chunk");
 304
 305         /* If it is data, queue it up, otherwise, send it
 306          * immediately.
 307          */
 308         if (sctp_chunk_is_data(chunk)) {
 309                 pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
 310                          __func__, q, chunk, chunk && chunk->chunk_hdr ?
 311                          sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
 312                          "illegal chunk");
 313
 314                 sctp_outq_tail_data(q, chunk);
 315                 if (chunk->asoc->peer.prsctp_capable &&
 316                     SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
 317                         chunk->asoc->sent_cnt_removable++;
 318                 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
 319                         SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
 320                 else
 321                         SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
 322         } else {
 323                 list_add_tail(&chunk->list, &q->control_chunk_list);
 324                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 325         }
 326
 327         if (!q->cork)
 328                 sctp_outq_flush(q, 0, gfp);
 329 }
 330
 331 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
 332  * and the abandoned list are in ascending order.
 333  */
 334 static void sctp_insert_list(struct list_head *head, struct list_head *new)
 335 {
 336         struct list_head *pos;
 337         struct sctp_chunk *nchunk, *lchunk;
 338         __u32 ntsn, ltsn;
 339         int done = 0;
 340
 341         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
 342         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
 343
 344         list_for_each(pos, head) {
 345                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
 346                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
 347                 if (TSN_lt(ntsn, ltsn)) {
 348                         list_add(new, pos->prev);
 349                         done = 1;
 350                         break;
 351                 }
 352         }
 353         if (!done)
 354                 list_add_tail(new, head);
 355 }
 356
 357 static int sctp_prsctp_prune_sent(struct sctp_association *asoc,
 358                                   struct sctp_sndrcvinfo *sinfo,
 359                                   struct list_head *queue, int msg_len)
 360 {
 361         struct sctp_chunk *chk, *temp;
 362
 363         list_for_each_entry_safe(chk, temp, queue, transmitted_list) {
 364                 struct sctp_stream_out *streamout;
 365
 366                 if (!chk->msg->abandoned &&
 367                     (!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
 368                      chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
 369                         continue;
 370
 371                 chk->msg->abandoned = 1;
 372                 list_del_init(&chk->transmitted_list);
 373                 sctp_insert_list(&asoc->outqueue.abandoned,
 374                                  &chk->transmitted_list);
 375
 376                 streamout = SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
 377                 asoc->sent_cnt_removable--;
 378                 asoc->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
 379                 streamout->ext->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
 380
 381                 if (queue != &asoc->outqueue.retransmit &&
 382                     !chk->tsn_gap_acked) {
 383                         if (chk->transport)
 384                                 chk->transport->flight_size -=
 385                                                 sctp_data_size(chk);
 386                         asoc->outqueue.outstanding_bytes -= sctp_data_size(chk);
 387                 }
 388
 389                 msg_len -= SCTP_DATA_SNDSIZE(chk) +
 390                            sizeof(struct sk_buff) +
 391                            sizeof(struct sctp_chunk);
 392                 if (msg_len <= 0)
 393                         break;
 394         }
 395
 396         return msg_len;
 397 }
 398
 399 static int sctp_prsctp_prune_unsent(struct sctp_association *asoc,
 400                                     struct sctp_sndrcvinfo *sinfo, int msg_len)
 401 {
 402         struct sctp_outq *q = &asoc->outqueue;
 403         struct sctp_chunk *chk, *temp;
 404
 405         q->sched->unsched_all(&asoc->stream);
 406
 407         list_for_each_entry_safe(chk, temp, &q->out_chunk_list, list) {
 408                 if (!chk->msg->abandoned &&
 409                     (!(chk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG) ||
 410                      !SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
 411                      chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
 412                         continue;
 413
 414                 chk->msg->abandoned = 1;
 415                 sctp_sched_dequeue_common(q, chk);
 416                 asoc->sent_cnt_removable--;
 417                 asoc->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
 418                 if (chk->sinfo.sinfo_stream < asoc->stream.outcnt) {
 419                         struct sctp_stream_out *streamout =
 420                                 SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
 421
 422                         streamout->ext->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
 423                 }
 424
 425                 msg_len -= SCTP_DATA_SNDSIZE(chk) +
 426                            sizeof(struct sk_buff) +
 427                            sizeof(struct sctp_chunk);
 428                 sctp_chunk_free(chk);
 429                 if (msg_len <= 0)
 430                         break;
 431         }
 432
 433         q->sched->sched_all(&asoc->stream);
 434
 435         return msg_len;
 436 }
 437
 438 /* Abandon the chunks according their priorities */
 439 void sctp_prsctp_prune(struct sctp_association *asoc,
 440                        struct sctp_sndrcvinfo *sinfo, int msg_len)
 441 {
 442         struct sctp_transport *transport;
 443
 444         if (!asoc->peer.prsctp_capable || !asoc->sent_cnt_removable)
 445                 return;
 446
 447         msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
 448                                          &asoc->outqueue.retransmit,
 449                                          msg_len);
 450         if (msg_len <= 0)
 451                 return;
 452
 453         list_for_each_entry(transport, &asoc->peer.transport_addr_list,
 454                             transports) {
 455                 msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
 456                                                  &transport->transmitted,
 457                                                  msg_len);
 458                 if (msg_len <= 0)
 459                         return;
 460         }
 461
 462         sctp_prsctp_prune_unsent(asoc, sinfo, msg_len);
 463 }
 464
 465 /* Mark all the eligible packets on a transport for retransmission.  */
 466 void sctp_retransmit_mark(struct sctp_outq *q,
 467                           struct sctp_transport *transport,
 468                           __u8 reason)
 469 {
 470         struct list_head *lchunk, *ltemp;
 471         struct sctp_chunk *chunk;
 472
 473         /* Walk through the specified transmitted queue.  */
 474         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
 475                 chunk = list_entry(lchunk, struct sctp_chunk,
 476                                    transmitted_list);
 477
 478                 /* If the chunk is abandoned, move it to abandoned list. */
 479                 if (sctp_chunk_abandoned(chunk)) {
 480                         list_del_init(lchunk);
 481                         sctp_insert_list(&q->abandoned, lchunk);
 482
 483                         /* If this chunk has not been previousely acked,
 484                          * stop considering it 'outstanding'.  Our peer
 485                          * will most likely never see it since it will
 486                          * not be retransmitted
 487                          */
 488                         if (!chunk->tsn_gap_acked) {
 489                                 if (chunk->transport)
 490                                         chunk->transport->flight_size -=
 491                                                         sctp_data_size(chunk);
 492                                 q->outstanding_bytes -= sctp_data_size(chunk);
 493                                 q->asoc->peer.rwnd += sctp_data_size(chunk);
 494                         }
 495                         continue;
 496                 }
 497
 498                 /* If we are doing  retransmission due to a timeout or pmtu
 499                  * discovery, only the  chunks that are not yet acked should
 500                  * be added to the retransmit queue.
 501                  */
 502                 if ((reason == SCTP_RTXR_FAST_RTX  &&
 503                             (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
 504                     (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
 505                         /* RFC 2960 6.2.1 Processing a Received SACK
 506                          *
 507                          * C) Any time a DATA chunk is marked for
 508                          * retransmission (via either T3-rtx timer expiration
 509                          * (Section 6.3.3) or via fast retransmit
 510                          * (Section 7.2.4)), add the data size of those
 511                          * chunks to the rwnd.
 512                          */
 513                         q->asoc->peer.rwnd += sctp_data_size(chunk);
 514                         q->outstanding_bytes -= sctp_data_size(chunk);
 515                         if (chunk->transport)
 516                                 transport->flight_size -= sctp_data_size(chunk);
 517
 518                         /* sctpimpguide-05 Section 2.8.2
 519                          * M5) If a T3-rtx timer expires, the
 520                          * 'TSN.Missing.Report' of all affected TSNs is set
 521                          * to 0.
 522                          */
 523                         chunk->tsn_missing_report = 0;
 524
 525                         /* If a chunk that is being used for RTT measurement
 526                          * has to be retransmitted, we cannot use this chunk
 527                          * anymore for RTT measurements. Reset rto_pending so
 528                          * that a new RTT measurement is started when a new
 529                          * data chunk is sent.
 530                          */
 531                         if (chunk->rtt_in_progress) {
 532                                 chunk->rtt_in_progress = 0;
 533                                 transport->rto_pending = 0;
 534                         }
 535
 536                         /* Move the chunk to the retransmit queue. The chunks
 537                          * on the retransmit queue are always kept in order.
 538                          */
 539                         list_del_init(lchunk);
 540                         sctp_insert_list(&q->retransmit, lchunk);
 541                 }
 542         }
 543
 544         pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, "
 545                  "flight_size:%d, pba:%d\n", __func__, transport, reason,
 546                  transport->cwnd, transport->ssthresh, transport->flight_size,
 547                  transport->partial_bytes_acked);
 548 }
 549
 550 /* Mark all the eligible packets on a transport for retransmission and force
 551  * one packet out.
 552  */
 553 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
 554                      enum sctp_retransmit_reason reason)
 555 {
 556         struct net *net = sock_net(q->asoc->base.sk);
 557
 558         switch (reason) {
 559         case SCTP_RTXR_T3_RTX:
 560                 SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
 561                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
 562                 /* Update the retran path if the T3-rtx timer has expired for
 563                  * the current retran path.
 564                  */
 565                 if (transport == transport->asoc->peer.retran_path)
 566                         sctp_assoc_update_retran_path(transport->asoc);
 567                 transport->asoc->rtx_data_chunks +=
 568                         transport->asoc->unack_data;
 569                 break;
 570         case SCTP_RTXR_FAST_RTX:
 571                 SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
 572                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
 573                 q->fast_rtx = 1;
 574                 break;
 575         case SCTP_RTXR_PMTUD:
 576                 SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
 577                 break;
 578         case SCTP_RTXR_T1_RTX:
 579                 SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
 580                 transport->asoc->init_retries++;
 581                 break;
 582         default:
 583                 BUG();
 584         }
 585
 586         sctp_retransmit_mark(q, transport, reason);
 587
 588         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
 589          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
 590          * following the procedures outlined in C1 - C5.
 591          */
 592         if (reason == SCTP_RTXR_T3_RTX)
 593                 q->asoc->stream.si->generate_ftsn(q, q->asoc->ctsn_ack_point);
 594
 595         /* Flush the queues only on timeout, since fast_rtx is only
 596          * triggered during sack processing and the queue
 597          * will be flushed at the end.
 598          */
 599         if (reason != SCTP_RTXR_FAST_RTX)
 600                 sctp_outq_flush(q, /* rtx_timeout */ 1, GFP_ATOMIC);
 601 }
 602
 603 /*
 604  * Transmit DATA chunks on the retransmit queue.  Upon return from
 605  * __sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
 606  * need to be transmitted by the caller.
 607  * We assume that pkt->transport has already been set.
 608  *
 609  * The return value is a normal kernel error return value.
 610  */
 611 static int __sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 612                                  int rtx_timeout, int *start_timer, gfp_t gfp)
 613 {
 614         struct sctp_transport *transport = pkt->transport;
 615         struct sctp_chunk *chunk, *chunk1;
 616         struct list_head *lqueue;
 617         enum sctp_xmit status;
 618         int error = 0;
 619         int timer = 0;
 620         int done = 0;
 621         int fast_rtx;
 622
 623         lqueue = &q->retransmit;
 624         fast_rtx = q->fast_rtx;
 625
 626         /* This loop handles time-out retransmissions, fast retransmissions,
 627          * and retransmissions due to opening of whindow.
 628          *
 629          * RFC 2960 6.3.3 Handle T3-rtx Expiration
 630          *
 631          * E3) Determine how many of the earliest (i.e., lowest TSN)
 632          * outstanding DATA chunks for the address for which the
 633          * T3-rtx has expired will fit into a single packet, subject
 634          * to the MTU constraint for the path corresponding to the
 635          * destination transport address to which the retransmission
 636          * is being sent (this may be different from the address for
 637          * which the timer expires [see Section 6.4]). Call this value
 638          * K. Bundle and retransmit those K DATA chunks in a single
 639          * packet to the destination endpoint.
 640          *
 641          * [Just to be painfully clear, if we are retransmitting
 642          * because a timeout just happened, we should send only ONE
 643          * packet of retransmitted data.]
 644          *
 645          * For fast retransmissions we also send only ONE packet.  However,
 646          * if we are just flushing the queue due to open window, we'll
 647          * try to send as much as possible.
 648          */
 649         list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
 650                 /* If the chunk is abandoned, move it to abandoned list. */
 651                 if (sctp_chunk_abandoned(chunk)) {
 652                         list_del_init(&chunk->transmitted_list);
 653                         sctp_insert_list(&q->abandoned,
 654                                          &chunk->transmitted_list);
 655                         continue;
 656                 }
 657
 658                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
 659                  * simple approach is just to move such TSNs out of the
 660                  * way and into a 'transmitted' queue and skip to the
 661                  * next chunk.
 662                  */
 663                 if (chunk->tsn_gap_acked) {
 664                         list_move_tail(&chunk->transmitted_list,
 665                                        &transport->transmitted);
 666                         continue;
 667                 }
 668
 669                 /* If we are doing fast retransmit, ignore non-fast_rtransmit
 670                  * chunks
 671                  */
 672                 if (fast_rtx && !chunk->fast_retransmit)
 673                         continue;
 674
 675 redo:
 676                 /* Attempt to append this chunk to the packet. */
 677                 status = sctp_packet_append_chunk(pkt, chunk);
 678
 679                 switch (status) {
 680                 case SCTP_XMIT_PMTU_FULL:
 681                         if (!pkt->has_data && !pkt->has_cookie_echo) {
 682                                 /* If this packet did not contain DATA then
 683                                  * retransmission did not happen, so do it
 684                                  * again.  We'll ignore the error here since
 685                                  * control chunks are already freed so there
 686                                  * is nothing we can do.
 687                                  */
 688                                 sctp_packet_transmit(pkt, gfp);
 689                                 goto redo;
 690                         }
 691
 692                         /* Send this packet.  */
 693                         error = sctp_packet_transmit(pkt, gfp);
 694
 695                         /* If we are retransmitting, we should only
 696                          * send a single packet.
 697                          * Otherwise, try appending this chunk again.
 698                          */
 699                         if (rtx_timeout || fast_rtx)
 700                                 done = 1;
 701                         else
 702                                 goto redo;
 703
 704                         /* Bundle next chunk in the next round.  */
 705                         break;
 706
 707                 case SCTP_XMIT_RWND_FULL:
 708                         /* Send this packet. */
 709                         error = sctp_packet_transmit(pkt, gfp);
 710
 711                         /* Stop sending DATA as there is no more room
 712                          * at the receiver.
 713                          */
 714                         done = 1;
 715                         break;
 716
 717                 case SCTP_XMIT_DELAY:
 718                         /* Send this packet. */
 719                         error = sctp_packet_transmit(pkt, gfp);
 720
 721                         /* Stop sending DATA because of nagle delay. */
 722                         done = 1;
 723                         break;
 724
 725                 default:
 726                         /* The append was successful, so add this chunk to
 727                          * the transmitted list.
 728                          */
 729                         list_move_tail(&chunk->transmitted_list,
 730                                        &transport->transmitted);
 731
 732                         /* Mark the chunk as ineligible for fast retransmit
 733                          * after it is retransmitted.
 734                          */
 735                         if (chunk->fast_retransmit == SCTP_NEED_FRTX)
 736                                 chunk->fast_retransmit = SCTP_DONT_FRTX;
 737
 738                         q->asoc->stats.rtxchunks++;
 739                         break;
 740                 }
 741
 742                 /* Set the timer if there were no errors */
 743                 if (!error && !timer)
 744                         timer = 1;
 745
 746                 if (done)
 747                         break;
 748         }
 749
 750         /* If we are here due to a retransmit timeout or a fast
 751          * retransmit and if there are any chunks left in the retransmit
 752          * queue that could not fit in the PMTU sized packet, they need
 753          * to be marked as ineligible for a subsequent fast retransmit.
 754          */
 755         if (rtx_timeout || fast_rtx) {
 756                 list_for_each_entry(chunk1, lqueue, transmitted_list) {
 757                         if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
 758                                 chunk1->fast_retransmit = SCTP_DONT_FRTX;
 759                 }
 760         }
 761
 762         *start_timer = timer;
 763
 764         /* Clear fast retransmit hint */
 765         if (fast_rtx)
 766                 q->fast_rtx = 0;
 767
 768         return error;
 769 }
 770
 771 /* Cork the outqueue so queued chunks are really queued. */
 772 void sctp_outq_uncork(struct sctp_outq *q, gfp_t gfp)
 773 {
 774         if (q->cork)
 775                 q->cork = 0;
 776
 777         sctp_outq_flush(q, 0, gfp);
 778 }
 779
 780 static int sctp_packet_singleton(struct sctp_transport *transport,
 781                                  struct sctp_chunk *chunk, gfp_t gfp)
 782 {
 783         const struct sctp_association *asoc = transport->asoc;
 784         const __u16 sport = asoc->base.bind_addr.port;
 785         const __u16 dport = asoc->peer.port;
 786         const __u32 vtag = asoc->peer.i.init_tag;
 787         struct sctp_packet singleton;
 788
 789         sctp_packet_init(&singleton, transport, sport, dport);
 790         sctp_packet_config(&singleton, vtag, 0);
 791         sctp_packet_append_chunk(&singleton, chunk);
 792         return sctp_packet_transmit(&singleton, gfp);
 793 }
 794
 795 /* Struct to hold the context during sctp outq flush */
 796 struct sctp_flush_ctx {
 797         struct sctp_outq *q;
 798         /* Current transport being used. It's NOT the same as curr active one */
 799         struct sctp_transport *transport;
 800         /* These transports have chunks to send. */
 801         struct list_head transport_list;
 802         struct sctp_association *asoc;
 803         /* Packet on the current transport above */
 804         struct sctp_packet *packet;
 805         gfp_t gfp;
 806 };
 807
 808 /* transport: current transport */
 809 static void sctp_outq_select_transport(struct sctp_flush_ctx *ctx,
 810                                        struct sctp_chunk *chunk)
 811 {
 812         struct sctp_transport *new_transport = chunk->transport;
 813
 814         if (!new_transport) {
 815                 if (!sctp_chunk_is_data(chunk)) {
 816                         /* If we have a prior transport pointer, see if
 817                          * the destination address of the chunk
 818                          * matches the destination address of the
 819                          * current transport.  If not a match, then
 820                          * try to look up the transport with a given
 821                          * destination address.  We do this because
 822                          * after processing ASCONFs, we may have new
 823                          * transports created.
 824                          */
 825                         if (ctx->transport && sctp_cmp_addr_exact(&chunk->dest,
 826                                                         &ctx->transport->ipaddr))
 827                                 new_transport = ctx->transport;
 828                         else
 829                                 new_transport = sctp_assoc_lookup_paddr(ctx->asoc,
 830                                                                   &chunk->dest);
 831                 }
 832
 833                 /* if we still don't have a new transport, then
 834                  * use the current active path.
 835                  */
 836                 if (!new_transport)
 837                         new_transport = ctx->asoc->peer.active_path;
 838         } else {
 839                 __u8 type;
 840
 841                 switch (new_transport->state) {
 842                 case SCTP_INACTIVE:
 843                 case SCTP_UNCONFIRMED:
 844                 case SCTP_PF:
 845                         /* If the chunk is Heartbeat or Heartbeat Ack,
 846                          * send it to chunk->transport, even if it's
 847                          * inactive.
 848                          *
 849                          * 3.3.6 Heartbeat Acknowledgement:
 850                          * ...
 851                          * A HEARTBEAT ACK is always sent to the source IP
 852                          * address of the IP datagram containing the
 853                          * HEARTBEAT chunk to which this ack is responding.
 854                          * ...
 855                          *
 856                          * ASCONF_ACKs also must be sent to the source.
 857                          */
 858                         type = chunk->chunk_hdr->type;
 859                         if (type != SCTP_CID_HEARTBEAT &&
 860                             type != SCTP_CID_HEARTBEAT_ACK &&
 861                             type != SCTP_CID_ASCONF_ACK)
 862                                 new_transport = ctx->asoc->peer.active_path;
 863                         break;
 864                 default:
 865                         break;
 866                 }
 867         }
 868
 869         /* Are we switching transports? Take care of transport locks. */
 870         if (new_transport != ctx->transport) {
 871                 ctx->transport = new_transport;
 872                 ctx->packet = &ctx->transport->packet;
 873
 874                 if (list_empty(&ctx->transport->send_ready))
 875                         list_add_tail(&ctx->transport->send_ready,
 876                                       &ctx->transport_list);
 877
 878                 sctp_packet_config(ctx->packet,
 879                                    ctx->asoc->peer.i.init_tag,
 880                                    ctx->asoc->peer.ecn_capable);
 881                 /* We've switched transports, so apply the
 882                  * Burst limit to the new transport.
 883                  */
 884                 sctp_transport_burst_limited(ctx->transport);
 885         }
 886 }
 887
 888 static void sctp_outq_flush_ctrl(struct sctp_flush_ctx *ctx)
 889 {
 890         struct sctp_chunk *chunk, *tmp;
 891         enum sctp_xmit status;
 892         int one_packet, error;
 893
 894         list_for_each_entry_safe(chunk, tmp, &ctx->q->control_chunk_list, list) {
 895                 one_packet = 0;
 896
 897                 /* RFC 5061, 5.3
 898                  * F1) This means that until such time as the ASCONF
 899                  * containing the add is acknowledged, the sender MUST
 900                  * NOT use the new IP address as a source for ANY SCTP
 901                  * packet except on carrying an ASCONF Chunk.
 902                  */
 903                 if (ctx->asoc->src_out_of_asoc_ok &&
 904                     chunk->chunk_hdr->type != SCTP_CID_ASCONF)
 905                         continue;
 906
 907                 list_del_init(&chunk->list);
 908
 909                 /* Pick the right transport to use. Should always be true for
 910                  * the first chunk as we don't have a transport by then.
 911                  */
 912                 sctp_outq_select_transport(ctx, chunk);
 913
 914                 switch (chunk->chunk_hdr->type) {
 915                 /* 6.10 Bundling
 916                  *   ...
 917                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
 918                  *   COMPLETE with any other chunks.  [Send them immediately.]
 919                  */
 920                 case SCTP_CID_INIT:
 921                 case SCTP_CID_INIT_ACK:
 922                 case SCTP_CID_SHUTDOWN_COMPLETE:
 923                         error = sctp_packet_singleton(ctx->transport, chunk,
 924                                                       ctx->gfp);
 925                         if (error < 0) {
 926                                 ctx->asoc->base.sk->sk_err = -error;
 927                                 return;
 928                         }
 929                         break;
 930
 931                 case SCTP_CID_ABORT:
 932                         if (sctp_test_T_bit(chunk))
 933                                 ctx->packet->vtag = ctx->asoc->c.my_vtag;
 934                         /* fallthru */
 935
 936                 /* The following chunks are "response" chunks, i.e.
 937                  * they are generated in response to something we
 938                  * received.  If we are sending these, then we can
 939                  * send only 1 packet containing these chunks.
 940                  */
 941                 case SCTP_CID_HEARTBEAT_ACK:
 942                 case SCTP_CID_SHUTDOWN_ACK:
 943                 case SCTP_CID_COOKIE_ACK:
 944                 case SCTP_CID_COOKIE_ECHO:
 945                 case SCTP_CID_ERROR:
 946                 case SCTP_CID_ECN_CWR:
 947                 case SCTP_CID_ASCONF_ACK:
 948                         one_packet = 1;
 949                         /* Fall through */
 950
 951                 case SCTP_CID_SACK:
 952                 case SCTP_CID_HEARTBEAT:
 953                 case SCTP_CID_SHUTDOWN:
 954                 case SCTP_CID_ECN_ECNE:
 955                 case SCTP_CID_ASCONF:
 956                 case SCTP_CID_FWD_TSN:
 957                 case SCTP_CID_I_FWD_TSN:
 958                 case SCTP_CID_RECONF:
 959                         status = sctp_packet_transmit_chunk(ctx->packet, chunk,
 960                                                             one_packet, ctx->gfp);
 961                         if (status != SCTP_XMIT_OK) {
 962                                 /* put the chunk back */
 963                                 list_add(&chunk->list, &ctx->q->control_chunk_list);
 964                                 break;
 965                         }
 966
 967                         ctx->asoc->stats.octrlchunks++;
 968                         /* PR-SCTP C5) If a FORWARD TSN is sent, the
 969                          * sender MUST assure that at least one T3-rtx
 970                          * timer is running.
 971                          */
 972                         if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN ||
 973                             chunk->chunk_hdr->type == SCTP_CID_I_FWD_TSN) {
 974                                 sctp_transport_reset_t3_rtx(ctx->transport);
 975                                 ctx->transport->last_time_sent = jiffies;
 976                         }
 977
 978                         if (chunk == ctx->asoc->strreset_chunk)
 979                                 sctp_transport_reset_reconf_timer(ctx->transport);
 980
 981                         break;
 982
 983                 default:
 984                         /* We built a chunk with an illegal type! */
 985                         BUG();
 986                 }
 987         }
 988 }
 989
 990 /* Returns false if new data shouldn't be sent */
 991 static bool sctp_outq_flush_rtx(struct sctp_flush_ctx *ctx,
 992                                 int rtx_timeout)
 993 {
 994         int error, start_timer = 0;
 995
 996         if (ctx->asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
 997                 return false;
 998
 999         if (ctx->transport != ctx->asoc->peer.retran_path) {
1000                 /* Switch transports & prepare the packet.  */
1001                 ctx->transport = ctx->asoc->peer.retran_path;
1002                 ctx->packet = &ctx->transport->packet;
1003
1004                 if (list_empty(&ctx->transport->send_ready))
1005                         list_add_tail(&ctx->transport->send_ready,
1006                                       &ctx->transport_list);
1007
1008                 sctp_packet_config(ctx->packet, ctx->asoc->peer.i.init_tag,
1009                                    ctx->asoc->peer.ecn_capable);
1010         }
1011
1012         error = __sctp_outq_flush_rtx(ctx->q, ctx->packet, rtx_timeout,
1013                                       &start_timer, ctx->gfp);
1014         if (error < 0)
1015                 ctx->asoc->base.sk->sk_err = -error;
1016
1017         if (start_timer) {
1018                 sctp_transport_reset_t3_rtx(ctx->transport);
1019                 ctx->transport->last_time_sent = jiffies;
1020         }
1021
1022         /* This can happen on COOKIE-ECHO resend.  Only
1023          * one chunk can get bundled with a COOKIE-ECHO.
1024          */
1025         if (ctx->packet->has_cookie_echo)
1026                 return false;
1027
1028         /* Don't send new data if there is still data
1029          * waiting to retransmit.
1030          */
1031         if (!list_empty(&ctx->q->retransmit))
1032                 return false;
1033
1034         return true;
1035 }
1036
1037 static void sctp_outq_flush_data(struct sctp_flush_ctx *ctx,
1038                                  int rtx_timeout)
1039 {
1040         struct sctp_chunk *chunk;
1041         enum sctp_xmit status;
1042
1043         /* Is it OK to send data chunks?  */
1044         switch (ctx->asoc->state) {
1045         case SCTP_STATE_COOKIE_ECHOED:
1046                 /* Only allow bundling when this packet has a COOKIE-ECHO
1047                  * chunk.
1048                  */
1049                 if (!ctx->packet || !ctx->packet->has_cookie_echo)
1050                         return;
1051
1052                 /* fall through */
1053         case SCTP_STATE_ESTABLISHED:
1054         case SCTP_STATE_SHUTDOWN_PENDING:
1055         case SCTP_STATE_SHUTDOWN_RECEIVED:
1056                 break;
1057
1058         default:
1059                 /* Do nothing. */
1060                 return;
1061         }
1062
1063         /* RFC 2960 6.1  Transmission of DATA Chunks
1064          *
1065          * C) When the time comes for the sender to transmit,
1066          * before sending new DATA chunks, the sender MUST
1067          * first transmit any outstanding DATA chunks which
1068          * are marked for retransmission (limited by the
1069          * current cwnd).
1070          */
1071         if (!list_empty(&ctx->q->retransmit) &&
1072             !sctp_outq_flush_rtx(ctx, rtx_timeout))
1073                 return;
1074
1075         /* Apply Max.Burst limitation to the current transport in
1076          * case it will be used for new data.  We are going to
1077          * rest it before we return, but we want to apply the limit
1078          * to the currently queued data.
1079          */
1080         if (ctx->transport)
1081                 sctp_transport_burst_limited(ctx->transport);
1082
1083         /* Finally, transmit new packets.  */
1084         while ((chunk = sctp_outq_dequeue_data(ctx->q)) != NULL) {
1085                 __u32 sid = ntohs(chunk->subh.data_hdr->stream);
1086                 __u8 stream_state = SCTP_SO(&ctx->asoc->stream, sid)->state;
1087
1088                 /* Has this chunk expired? */
1089                 if (sctp_chunk_abandoned(chunk)) {
1090                         sctp_sched_dequeue_done(ctx->q, chunk);
1091                         sctp_chunk_fail(chunk, 0);
1092                         sctp_chunk_free(chunk);
1093                         continue;
1094                 }
1095
1096                 if (stream_state == SCTP_STREAM_CLOSED) {
1097                         sctp_outq_head_data(ctx->q, chunk);
1098                         break;
1099                 }
1100
1101                 sctp_outq_select_transport(ctx, chunk);
1102
1103                 pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p skb->users:%d\n",
1104                          __func__, ctx->q, chunk, chunk && chunk->chunk_hdr ?
1105                          sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
1106                          "illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
1107                          chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
1108                          refcount_read(&chunk->skb->users) : -1);
1109
1110                 /* Add the chunk to the packet.  */
1111                 status = sctp_packet_transmit_chunk(ctx->packet, chunk, 0,
1112                                                     ctx->gfp);
1113                 if (status != SCTP_XMIT_OK) {
1114                         /* We could not append this chunk, so put
1115                          * the chunk back on the output queue.
1116                          */
1117                         pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
1118                                  __func__, ntohl(chunk->subh.data_hdr->tsn),
1119                                  status);
1120
1121                         sctp_outq_head_data(ctx->q, chunk);
1122                         break;
1123                 }
1124
1125                 /* The sender is in the SHUTDOWN-PENDING state,
1126                  * The sender MAY set the I-bit in the DATA
1127                  * chunk header.
1128                  */
1129                 if (ctx->asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1130                         chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1131                 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
1132                         ctx->asoc->stats.ouodchunks++;
1133                 else
1134                         ctx->asoc->stats.oodchunks++;
1135
1136                 /* Only now it's safe to consider this
1137                  * chunk as sent, sched-wise.
1138                  */
1139                 sctp_sched_dequeue_done(ctx->q, chunk);
1140
1141                 list_add_tail(&chunk->transmitted_list,
1142                               &ctx->transport->transmitted);
1143
1144                 sctp_transport_reset_t3_rtx(ctx->transport);
1145                 ctx->transport->last_time_sent = jiffies;
1146
1147                 /* Only let one DATA chunk get bundled with a
1148                  * COOKIE-ECHO chunk.
1149                  */
1150                 if (ctx->packet->has_cookie_echo)
1151                         break;
1152         }
1153 }
1154
1155 static void sctp_outq_flush_transports(struct sctp_flush_ctx *ctx)
1156 {
1157         struct list_head *ltransport;
1158         struct sctp_packet *packet;
1159         struct sctp_transport *t;
1160         int error = 0;
1161
1162         while ((ltransport = sctp_list_dequeue(&ctx->transport_list)) != NULL) {
1163                 t = list_entry(ltransport, struct sctp_transport, send_ready);
1164                 packet = &t->packet;
1165                 if (!sctp_packet_empty(packet)) {
1166                         error = sctp_packet_transmit(packet, ctx->gfp);
1167                         if (error < 0)
1168                                 ctx->q->asoc->base.sk->sk_err = -error;
1169                 }
1170
1171                 /* Clear the burst limited state, if any */
1172                 sctp_transport_burst_reset(t);
1173         }
1174 }
1175
1176 /* Try to flush an outqueue.
1177  *
1178  * Description: Send everything in q which we legally can, subject to
1179  * congestion limitations.
1180  * * Note: This function can be called from multiple contexts so appropriate
1181  * locking concerns must be made.  Today we use the sock lock to protect
1182  * this function.
1183  */
1184
1185 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
1186 {
1187         struct sctp_flush_ctx ctx = {
1188                 .q = q,
1189                 .transport = NULL,
1190                 .transport_list = LIST_HEAD_INIT(ctx.transport_list),
1191                 .asoc = q->asoc,
1192                 .packet = NULL,
1193                 .gfp = gfp,
1194         };
1195
1196         /* 6.10 Bundling
1197          *   ...
1198          *   When bundling control chunks with DATA chunks, an
1199          *   endpoint MUST place control chunks first in the outbound
1200          *   SCTP packet.  The transmitter MUST transmit DATA chunks
1201          *   within a SCTP packet in increasing order of TSN.
1202          *   ...
1203          */
1204
1205         sctp_outq_flush_ctrl(&ctx);
1206
1207         if (q->asoc->src_out_of_asoc_ok)
1208                 goto sctp_flush_out;
1209
1210         sctp_outq_flush_data(&ctx, rtx_timeout);
1211
1212 sctp_flush_out:
1213
1214         sctp_outq_flush_transports(&ctx);
1215 }
1216
1217 /* Update unack_data based on the incoming SACK chunk */
1218 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1219                                         struct sctp_sackhdr *sack)
1220 {
1221         union sctp_sack_variable *frags;
1222         __u16 unack_data;
1223         int i;
1224
1225         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1226
1227         frags = sack->variable;
1228         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1229                 unack_data -= ((ntohs(frags[i].gab.end) -
1230                                 ntohs(frags[i].gab.start) + 1));
1231         }
1232
1233         assoc->unack_data = unack_data;
1234 }
1235
1236 /* This is where we REALLY process a SACK.
1237  *
1238  * Process the SACK against the outqueue.  Mostly, this just frees
1239  * things off the transmitted queue.
1240  */
1241 int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1242 {
1243         struct sctp_association *asoc = q->asoc;
1244         struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1245         struct sctp_transport *transport;
1246         struct sctp_chunk *tchunk = NULL;
1247         struct list_head *lchunk, *transport_list, *temp;
1248         union sctp_sack_variable *frags = sack->variable;
1249         __u32 sack_ctsn, ctsn, tsn;
1250         __u32 highest_tsn, highest_new_tsn;
1251         __u32 sack_a_rwnd;
1252         unsigned int outstanding;
1253         struct sctp_transport *primary = asoc->peer.primary_path;
1254         int count_of_newacks = 0;
1255         int gap_ack_blocks;
1256         u8 accum_moved = 0;
1257
1258         /* Grab the association's destination address list. */
1259         transport_list = &asoc->peer.transport_addr_list;
1260
1261         /* SCTP path tracepoint for congestion control debugging. */
1262         list_for_each_entry(transport, transport_list, transports) {
1263                 trace_sctp_probe_path(transport, asoc);
1264         }
1265
1266         sack_ctsn = ntohl(sack->cum_tsn_ack);
1267         gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1268         asoc->stats.gapcnt += gap_ack_blocks;
1269         /*
1270          * SFR-CACC algorithm:
1271          * On receipt of a SACK the sender SHOULD execute the
1272          * following statements.
1273          *
1274          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1275          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1276          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1277          * all destinations.
1278          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1279          * is set the receiver of the SACK MUST take the following actions:
1280          *
1281          * A) Initialize the cacc_saw_newack to 0 for all destination
1282          * addresses.
1283          *
1284          * Only bother if changeover_active is set. Otherwise, this is
1285          * totally suboptimal to do on every SACK.
1286          */
1287         if (primary->cacc.changeover_active) {
1288                 u8 clear_cycling = 0;
1289
1290                 if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1291                         primary->cacc.changeover_active = 0;
1292                         clear_cycling = 1;
1293                 }
1294
1295                 if (clear_cycling || gap_ack_blocks) {
1296                         list_for_each_entry(transport, transport_list,
1297                                         transports) {
1298                                 if (clear_cycling)
1299                                         transport->cacc.cycling_changeover = 0;
1300                                 if (gap_ack_blocks)
1301                                         transport->cacc.cacc_saw_newack = 0;
1302                         }
1303                 }
1304         }
1305
1306         /* Get the highest TSN in the sack. */
1307         highest_tsn = sack_ctsn;
1308         if (gap_ack_blocks)
1309                 highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1310
1311         if (TSN_lt(asoc->highest_sacked, highest_tsn))
1312                 asoc->highest_sacked = highest_tsn;
1313
1314         highest_new_tsn = sack_ctsn;
1315
1316         /* Run through the retransmit queue.  Credit bytes received
1317          * and free those chunks that we can.
1318          */
1319         sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1320
1321         /* Run through the transmitted queue.
1322          * Credit bytes received and free those chunks which we can.
1323          *
1324          * This is a MASSIVE candidate for optimization.
1325          */
1326         list_for_each_entry(transport, transport_list, transports) {
1327                 sctp_check_transmitted(q, &transport->transmitted,
1328                                        transport, &chunk->source, sack,
1329                                        &highest_new_tsn);
1330                 /*
1331                  * SFR-CACC algorithm:
1332                  * C) Let count_of_newacks be the number of
1333                  * destinations for which cacc_saw_newack is set.
1334                  */
1335                 if (transport->cacc.cacc_saw_newack)
1336                         count_of_newacks++;
1337         }
1338
1339         /* Move the Cumulative TSN Ack Point if appropriate.  */
1340         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1341                 asoc->ctsn_ack_point = sack_ctsn;
1342                 accum_moved = 1;
1343         }
1344
1345         if (gap_ack_blocks) {
1346
1347                 if (asoc->fast_recovery && accum_moved)
1348                         highest_new_tsn = highest_tsn;
1349
1350                 list_for_each_entry(transport, transport_list, transports)
1351                         sctp_mark_missing(q, &transport->transmitted, transport,
1352                                           highest_new_tsn, count_of_newacks);
1353         }
1354
1355         /* Update unack_data field in the assoc. */
1356         sctp_sack_update_unack_data(asoc, sack);
1357
1358         ctsn = asoc->ctsn_ack_point;
1359
1360         /* Throw away stuff rotting on the sack queue.  */
1361         list_for_each_safe(lchunk, temp, &q->sacked) {
1362                 tchunk = list_entry(lchunk, struct sctp_chunk,
1363                                     transmitted_list);
1364                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1365                 if (TSN_lte(tsn, ctsn)) {
1366                         list_del_init(&tchunk->transmitted_list);
1367                         if (asoc->peer.prsctp_capable &&
1368                             SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
1369                                 asoc->sent_cnt_removable--;
1370                         sctp_chunk_free(tchunk);
1371                 }
1372         }
1373
1374         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1375          *     number of bytes still outstanding after processing the
1376          *     Cumulative TSN Ack and the Gap Ack Blocks.
1377          */
1378
1379         sack_a_rwnd = ntohl(sack->a_rwnd);
1380         asoc->peer.zero_window_announced = !sack_a_rwnd;
1381         outstanding = q->outstanding_bytes;
1382
1383         if (outstanding < sack_a_rwnd)
1384                 sack_a_rwnd -= outstanding;
1385         else
1386                 sack_a_rwnd = 0;
1387
1388         asoc->peer.rwnd = sack_a_rwnd;
1389
1390         asoc->stream.si->generate_ftsn(q, sack_ctsn);
1391
1392         pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
1393         pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
1394                  "advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
1395                  asoc->adv_peer_ack_point);
1396
1397         return sctp_outq_is_empty(q);
1398 }
1399
1400 /* Is the outqueue empty?
1401  * The queue is empty when we have not pending data, no in-flight data
1402  * and nothing pending retransmissions.
1403  */
1404 int sctp_outq_is_empty(const struct sctp_outq *q)
1405 {
1406         return q->out_qlen == 0 && q->outstanding_bytes == 0 &&
1407                list_empty(&q->retransmit);
1408 }
1409
1410 /********************************************************************
1411  * 2nd Level Abstractions
1412  ********************************************************************/
1413
1414 /* Go through a transport's transmitted list or the association's retransmit
1415  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1416  * The retransmit list will not have an associated transport.
1417  *
1418  * I added coherent debug information output.   --xguo
1419  *
1420  * Instead of printing 'sacked' or 'kept' for each TSN on the
1421  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1422  * KEPT TSN6-TSN7, etc.
1423  */
1424 static void sctp_check_transmitted(struct sctp_outq *q,
1425                                    struct list_head *transmitted_queue,
1426                                    struct sctp_transport *transport,
1427                                    union sctp_addr *saddr,
1428                                    struct sctp_sackhdr *sack,
1429                                    __u32 *highest_new_tsn_in_sack)
1430 {
1431         struct list_head *lchunk;
1432         struct sctp_chunk *tchunk;
1433         struct list_head tlist;
1434         __u32 tsn;
1435         __u32 sack_ctsn;
1436         __u32 rtt;
1437         __u8 restart_timer = 0;
1438         int bytes_acked = 0;
1439         int migrate_bytes = 0;
1440         bool forward_progress = false;
1441
1442         sack_ctsn = ntohl(sack->cum_tsn_ack);
1443
1444         INIT_LIST_HEAD(&tlist);
1445
1446         /* The while loop will skip empty transmitted queues. */
1447         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1448                 tchunk = list_entry(lchunk, struct sctp_chunk,
1449                                     transmitted_list);
1450
1451                 if (sctp_chunk_abandoned(tchunk)) {
1452                         /* Move the chunk to abandoned list. */
1453                         sctp_insert_list(&q->abandoned, lchunk);
1454
1455                         /* If this chunk has not been acked, stop
1456                          * considering it as 'outstanding'.
1457                          */
1458                         if (transmitted_queue != &q->retransmit &&
1459                             !tchunk->tsn_gap_acked) {
1460                                 if (tchunk->transport)
1461                                         tchunk->transport->flight_size -=
1462                                                         sctp_data_size(tchunk);
1463                                 q->outstanding_bytes -= sctp_data_size(tchunk);
1464                         }
1465                         continue;
1466                 }
1467
1468                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1469                 if (sctp_acked(sack, tsn)) {
1470                         /* If this queue is the retransmit queue, the
1471                          * retransmit timer has already reclaimed
1472                          * the outstanding bytes for this chunk, so only
1473                          * count bytes associated with a transport.
1474                          */
1475                         if (transport && !tchunk->tsn_gap_acked) {
1476                                 /* If this chunk is being used for RTT
1477                                  * measurement, calculate the RTT and update
1478                                  * the RTO using this value.
1479                                  *
1480                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1481                                  * MUST NOT be made using packets that were
1482                                  * retransmitted (and thus for which it is
1483                                  * ambiguous whether the reply was for the
1484                                  * first instance of the packet or a later
1485                                  * instance).
1486                                  */
1487                                 if (!sctp_chunk_retransmitted(tchunk) &&
1488                                     tchunk->rtt_in_progress) {
1489                                         tchunk->rtt_in_progress = 0;
1490                                         rtt = jiffies - tchunk->sent_at;
1491                                         sctp_transport_update_rto(transport,
1492                                                                   rtt);
1493                                 }
1494
1495                                 if (TSN_lte(tsn, sack_ctsn)) {
1496                                         /*
1497                                          * SFR-CACC algorithm:
1498                                          * 2) If the SACK contains gap acks
1499                                          * and the flag CHANGEOVER_ACTIVE is
1500                                          * set the receiver of the SACK MUST
1501                                          * take the following action:
1502                                          *
1503                                          * B) For each TSN t being acked that
1504                                          * has not been acked in any SACK so
1505                                          * far, set cacc_saw_newack to 1 for
1506                                          * the destination that the TSN was
1507                                          * sent to.
1508                                          */
1509                                         if (sack->num_gap_ack_blocks &&
1510                                             q->asoc->peer.primary_path->cacc.
1511                                             changeover_active)
1512                                                 transport->cacc.cacc_saw_newack
1513                                                         = 1;
1514                                 }
1515                         }
1516
1517                         /* If the chunk hasn't been marked as ACKED,
1518                          * mark it and account bytes_acked if the
1519                          * chunk had a valid transport (it will not
1520                          * have a transport if ASCONF had deleted it
1521                          * while DATA was outstanding).
1522                          */
1523                         if (!tchunk->tsn_gap_acked) {
1524                                 tchunk->tsn_gap_acked = 1;
1525                                 if (TSN_lt(*highest_new_tsn_in_sack, tsn))
1526                                         *highest_new_tsn_in_sack = tsn;
1527                                 bytes_acked += sctp_data_size(tchunk);
1528                                 if (!tchunk->transport)
1529                                         migrate_bytes += sctp_data_size(tchunk);
1530                                 forward_progress = true;
1531                         }
1532
1533                         if (TSN_lte(tsn, sack_ctsn)) {
1534                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1535                                  *
1536                                  * R3) Whenever a SACK is received
1537                                  * that acknowledges the DATA chunk
1538                                  * with the earliest outstanding TSN
1539                                  * for that address, restart T3-rtx
1540                                  * timer for that address with its
1541                                  * current RTO.
1542                                  */
1543                                 restart_timer = 1;
1544                                 forward_progress = true;
1545
1546                                 list_add_tail(&tchunk->transmitted_list,
1547                                               &q->sacked);
1548                         } else {
1549                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1550                                  * M2) Each time a SACK arrives reporting
1551                                  * 'Stray DATA chunk(s)' record the highest TSN
1552                                  * reported as newly acknowledged, call this
1553                                  * value 'HighestTSNinSack'. A newly
1554                                  * acknowledged DATA chunk is one not
1555                                  * previously acknowledged in a SACK.
1556                                  *
1557                                  * When the SCTP sender of data receives a SACK
1558                                  * chunk that acknowledges, for the first time,
1559                                  * the receipt of a DATA chunk, all the still
1560                                  * unacknowledged DATA chunks whose TSN is
1561                                  * older than that newly acknowledged DATA
1562                                  * chunk, are qualified as 'Stray DATA chunks'.
1563                                  */
1564                                 list_add_tail(lchunk, &tlist);
1565                         }
1566                 } else {
1567                         if (tchunk->tsn_gap_acked) {
1568                                 pr_debug("%s: receiver reneged on data TSN:0x%x\n",
1569                                          __func__, tsn);
1570
1571                                 tchunk->tsn_gap_acked = 0;
1572
1573                                 if (tchunk->transport)
1574                                         bytes_acked -= sctp_data_size(tchunk);
1575
1576                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1577                                  *
1578                                  * R4) Whenever a SACK is received missing a
1579                                  * TSN that was previously acknowledged via a
1580                                  * Gap Ack Block, start T3-rtx for the
1581                                  * destination address to which the DATA
1582                                  * chunk was originally
1583                                  * transmitted if it is not already running.
1584                                  */
1585                                 restart_timer = 1;
1586                         }
1587
1588                         list_add_tail(lchunk, &tlist);
1589                 }
1590         }
1591
1592         if (transport) {
1593                 if (bytes_acked) {
1594                         struct sctp_association *asoc = transport->asoc;
1595
1596                         /* We may have counted DATA that was migrated
1597                          * to this transport due to DEL-IP operation.
1598                          * Subtract those bytes, since the were never
1599                          * send on this transport and shouldn't be
1600                          * credited to this transport.
1601                          */
1602                         bytes_acked -= migrate_bytes;
1603
1604                         /* 8.2. When an outstanding TSN is acknowledged,
1605                          * the endpoint shall clear the error counter of
1606                          * the destination transport address to which the
1607                          * DATA chunk was last sent.
1608                          * The association's overall error counter is
1609                          * also cleared.
1610                          */
1611                         transport->error_count = 0;
1612                         transport->asoc->overall_error_count = 0;
1613                         forward_progress = true;
1614
1615                         /*
1616                          * While in SHUTDOWN PENDING, we may have started
1617                          * the T5 shutdown guard timer after reaching the
1618                          * retransmission limit. Stop that timer as soon
1619                          * as the receiver acknowledged any data.
1620                          */
1621                         if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1622                             del_timer(&asoc->timers
1623                                 [SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1624                                         sctp_association_put(asoc);
1625
1626                         /* Mark the destination transport address as
1627                          * active if it is not so marked.
1628                          */
1629                         if ((transport->state == SCTP_INACTIVE ||
1630                              transport->state == SCTP_UNCONFIRMED) &&
1631                             sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1632                                 sctp_assoc_control_transport(
1633                                         transport->asoc,
1634                                         transport,
1635                                         SCTP_TRANSPORT_UP,
1636                                         SCTP_RECEIVED_SACK);
1637                         }
1638
1639                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1640                                                   bytes_acked);
1641
1642                         transport->flight_size -= bytes_acked;
1643                         if (transport->flight_size == 0)
1644                                 transport->partial_bytes_acked = 0;
1645                         q->outstanding_bytes -= bytes_acked + migrate_bytes;
1646                 } else {
1647                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1648                          * When a sender is doing zero window probing, it
1649                          * should not timeout the association if it continues
1650                          * to receive new packets from the receiver. The
1651                          * reason is that the receiver MAY keep its window
1652                          * closed for an indefinite time.
1653                          * A sender is doing zero window probing when the
1654                          * receiver's advertised window is zero, and there is
1655                          * only one data chunk in flight to the receiver.
1656                          *
1657                          * Allow the association to timeout while in SHUTDOWN
1658                          * PENDING or SHUTDOWN RECEIVED in case the receiver
1659                          * stays in zero window mode forever.
1660                          */
1661                         if (!q->asoc->peer.rwnd &&
1662                             !list_empty(&tlist) &&
1663                             (sack_ctsn+2 == q->asoc->next_tsn) &&
1664                             q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1665                                 pr_debug("%s: sack received for zero window "
1666                                          "probe:%u\n", __func__, sack_ctsn);
1667
1668                                 q->asoc->overall_error_count = 0;
1669                                 transport->error_count = 0;
1670                         }
1671                 }
1672
1673                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1674                  *
1675                  * R2) Whenever all outstanding data sent to an address have
1676                  * been acknowledged, turn off the T3-rtx timer of that
1677                  * address.
1678                  */
1679                 if (!transport->flight_size) {
1680                         if (del_timer(&transport->T3_rtx_timer))
1681                                 sctp_transport_put(transport);
1682                 } else if (restart_timer) {
1683                         if (!mod_timer(&transport->T3_rtx_timer,
1684                                        jiffies + transport->rto))
1685                                 sctp_transport_hold(transport);
1686                 }
1687
1688                 if (forward_progress) {
1689                         if (transport->dst)
1690                                 sctp_transport_dst_confirm(transport);
1691                 }
1692         }
1693
1694         list_splice(&tlist, transmitted_queue);
1695 }
1696
1697 /* Mark chunks as missing and consequently may get retransmitted. */
1698 static void sctp_mark_missing(struct sctp_outq *q,
1699                               struct list_head *transmitted_queue,
1700                               struct sctp_transport *transport,
1701                               __u32 highest_new_tsn_in_sack,
1702                               int count_of_newacks)
1703 {
1704         struct sctp_chunk *chunk;
1705         __u32 tsn;
1706         char do_fast_retransmit = 0;
1707         struct sctp_association *asoc = q->asoc;
1708         struct sctp_transport *primary = asoc->peer.primary_path;
1709
1710         list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1711
1712                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1713
1714                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1715                  * 'Unacknowledged TSN's', if the TSN number of an
1716                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1717                  * value, increment the 'TSN.Missing.Report' count on that
1718                  * chunk if it has NOT been fast retransmitted or marked for
1719                  * fast retransmit already.
1720                  */
1721                 if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1722                     !chunk->tsn_gap_acked &&
1723                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1724
1725                         /* SFR-CACC may require us to skip marking
1726                          * this chunk as missing.
1727                          */
1728                         if (!transport || !sctp_cacc_skip(primary,
1729                                                 chunk->transport,
1730                                                 count_of_newacks, tsn)) {
1731                                 chunk->tsn_missing_report++;
1732
1733                                 pr_debug("%s: tsn:0x%x missing counter:%d\n",
1734                                          __func__, tsn, chunk->tsn_missing_report);
1735                         }
1736                 }
1737                 /*
1738                  * M4) If any DATA chunk is found to have a
1739                  * 'TSN.Missing.Report'
1740                  * value larger than or equal to 3, mark that chunk for
1741                  * retransmission and start the fast retransmit procedure.
1742                  */
1743
1744                 if (chunk->tsn_missing_report >= 3) {
1745                         chunk->fast_retransmit = SCTP_NEED_FRTX;
1746                         do_fast_retransmit = 1;
1747                 }
1748         }
1749
1750         if (transport) {
1751                 if (do_fast_retransmit)
1752                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1753
1754                 pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
1755                          "flight_size:%d, pba:%d\n",  __func__, transport,
1756                          transport->cwnd, transport->ssthresh,
1757                          transport->flight_size, transport->partial_bytes_acked);
1758         }
1759 }
1760
1761 /* Is the given TSN acked by this packet?  */
1762 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1763 {
1764         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1765         union sctp_sack_variable *frags;
1766         __u16 tsn_offset, blocks;
1767         int i;
1768
1769         if (TSN_lte(tsn, ctsn))
1770                 goto pass;
1771
1772         /* 3.3.4 Selective Acknowledgment (SACK) (3):
1773          *
1774          * Gap Ack Blocks:
1775          *  These fields contain the Gap Ack Blocks. They are repeated
1776          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1777          *  defined in the Number of Gap Ack Blocks field. All DATA
1778          *  chunks with TSNs greater than or equal to (Cumulative TSN
1779          *  Ack + Gap Ack Block Start) and less than or equal to
1780          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1781          *  Block are assumed to have been received correctly.
1782          */
1783
1784         frags = sack->variable;
1785         blocks = ntohs(sack->num_gap_ack_blocks);
1786         tsn_offset = tsn - ctsn;
1787         for (i = 0; i < blocks; ++i) {
1788                 if (tsn_offset >= ntohs(frags[i].gab.start) &&
1789                     tsn_offset <= ntohs(frags[i].gab.end))
1790                         goto pass;
1791         }
1792
1793         return 0;
1794 pass:
1795         return 1;
1796 }
1797
1798 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1799                                     int nskips, __be16 stream)
1800 {
1801         int i;
1802
1803         for (i = 0; i < nskips; i++) {
1804                 if (skiplist[i].stream == stream)
1805                         return i;
1806         }
1807         return i;
1808 }
1809
1810 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1811 void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1812 {
1813         struct sctp_association *asoc = q->asoc;
1814         struct sctp_chunk *ftsn_chunk = NULL;
1815         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1816         int nskips = 0;
1817         int skip_pos = 0;
1818         __u32 tsn;
1819         struct sctp_chunk *chunk;
1820         struct list_head *lchunk, *temp;
1821
1822         if (!asoc->peer.prsctp_capable)
1823                 return;
1824
1825         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1826          * received SACK.
1827          *
1828          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1829          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1830          */
1831         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1832                 asoc->adv_peer_ack_point = ctsn;
1833
1834         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1835          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1836          * the chunk next in the out-queue space is marked as "abandoned" as
1837          * shown in the following example:
1838          *
1839          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1840          * and the Advanced.Peer.Ack.Point is updated to this value:
1841          *
1842          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1843          *   normal SACK processing           local advancement
1844          *                ...                           ...
1845          *   Adv.Ack.Pt-> 102 acked                     102 acked
1846          *                103 abandoned                 103 abandoned
1847          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1848          *                105                           105
1849          *                106 acked                     106 acked
1850          *                ...                           ...
1851          *
1852          * In this example, the data sender successfully advanced the
1853          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1854          */
1855         list_for_each_safe(lchunk, temp, &q->abandoned) {
1856                 chunk = list_entry(lchunk, struct sctp_chunk,
1857                                         transmitted_list);
1858                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1859
1860                 /* Remove any chunks in the abandoned queue that are acked by
1861                  * the ctsn.
1862                  */
1863                 if (TSN_lte(tsn, ctsn)) {
1864                         list_del_init(lchunk);
1865                         sctp_chunk_free(chunk);
1866                 } else {
1867                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1868                                 asoc->adv_peer_ack_point = tsn;
1869                                 if (chunk->chunk_hdr->flags &
1870                                          SCTP_DATA_UNORDERED)
1871                                         continue;
1872                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1873                                                 nskips,
1874                                                 chunk->subh.data_hdr->stream);
1875                                 ftsn_skip_arr[skip_pos].stream =
1876                                         chunk->subh.data_hdr->stream;
1877                                 ftsn_skip_arr[skip_pos].ssn =
1878                                          chunk->subh.data_hdr->ssn;
1879                                 if (skip_pos == nskips)
1880                                         nskips++;
1881                                 if (nskips == 10)
1882                                         break;
1883                         } else
1884                                 break;
1885                 }
1886         }
1887
1888         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1889          * is greater than the Cumulative TSN ACK carried in the received
1890          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1891          * chunk containing the latest value of the
1892          * "Advanced.Peer.Ack.Point".
1893          *
1894          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1895          * list each stream and sequence number in the forwarded TSN. This
1896          * information will enable the receiver to easily find any
1897          * stranded TSN's waiting on stream reorder queues. Each stream
1898          * SHOULD only be reported once; this means that if multiple
1899          * abandoned messages occur in the same stream then only the
1900          * highest abandoned stream sequence number is reported. If the
1901          * total size of the FORWARD TSN does NOT fit in a single MTU then
1902          * the sender of the FORWARD TSN SHOULD lower the
1903          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1904          * single MTU.
1905          */
1906         if (asoc->adv_peer_ack_point > ctsn)
1907                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1908                                               nskips, &ftsn_skip_arr[0]);
1909
1910         if (ftsn_chunk) {
1911                 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1912                 SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_OUTCTRLCHUNKS);
1913         }
1914 }