linux/net/sctp/outqueue.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/* SCTP kernel implementation
   3 * (C) Copyright IBM Corp. 2001, 2004
   4 * Copyright (c) 1999-2000 Cisco, Inc.
   5 * Copyright (c) 1999-2001 Motorola, Inc.
   6 * Copyright (c) 2001-2003 Intel Corp.
   7 *
   8 * This file is part of the SCTP kernel implementation
   9 *
  10 * These functions implement the sctp_outq class.   The outqueue handles
  11 * bundling and queueing of outgoing SCTP chunks.
  12 *
  13 * Please send any bug reports or fixes you make to the
  14 * email address(es):
  15 *    lksctp developers <linux-sctp@vger.kernel.org>
  16 *
  17 * Written or modified by:
  18 *    La Monte H.P. Yarroll <piggy@acm.org>
  19 *    Karl Knutson          <karl@athena.chicago.il.us>
  20 *    Perry Melange         <pmelange@null.cc.uic.edu>
  21 *    Xingang Guo           <xingang.guo@intel.com>
  22 *    Hui Huang             <hui.huang@nokia.com>
  23 *    Sridhar Samudrala     <sri@us.ibm.com>
  24 *    Jon Grimm             <jgrimm@us.ibm.com>
  25 */
  26
  27#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  28
  29#include <linux/types.h>
  30#include <linux/list.h>   /* For struct list_head */
  31#include <linux/socket.h>
  32#include <linux/ip.h>
  33#include <linux/slab.h>
  34#include <net/sock.h>     /* For skb_set_owner_w */
  35
  36#include <net/sctp/sctp.h>
  37#include <net/sctp/sm.h>
  38#include <net/sctp/stream_sched.h>
  39#include <trace/events/sctp.h>
  40
  41/* Declare internal functions here.  */
  42static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
  43static void sctp_check_transmitted(struct sctp_outq *q,
  44                                   struct list_head *transmitted_queue,
  45                                   struct sctp_transport *transport,
  46                                   union sctp_addr *saddr,
  47                                   struct sctp_sackhdr *sack,
  48                                   __u32 *highest_new_tsn);
  49
  50static void sctp_mark_missing(struct sctp_outq *q,
  51                              struct list_head *transmitted_queue,
  52                              struct sctp_transport *transport,
  53                              __u32 highest_new_tsn,
  54                              int count_of_newacks);
  55
  56static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp);
  57
  58/* Add data to the front of the queue. */
  59static inline void sctp_outq_head_data(struct sctp_outq *q,
  60                                       struct sctp_chunk *ch)
  61{
  62        struct sctp_stream_out_ext *oute;
  63        __u16 stream;
  64
  65        list_add(&ch->list, &q->out_chunk_list);
  66        q->out_qlen += ch->skb->len;
  67
  68        stream = sctp_chunk_stream_no(ch);
  69        oute = SCTP_SO(&q->asoc->stream, stream)->ext;
  70        list_add(&ch->stream_list, &oute->outq);
  71}
  72
  73/* Take data from the front of the queue. */
  74static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
  75{
  76        return q->sched->dequeue(q);
  77}
  78
  79/* Add data chunk to the end of the queue. */
  80static inline void sctp_outq_tail_data(struct sctp_outq *q,
  81                                       struct sctp_chunk *ch)
  82{
  83        struct sctp_stream_out_ext *oute;
  84        __u16 stream;
  85
  86        list_add_tail(&ch->list, &q->out_chunk_list);
  87        q->out_qlen += ch->skb->len;
  88
  89        stream = sctp_chunk_stream_no(ch);
  90        oute = SCTP_SO(&q->asoc->stream, stream)->ext;
  91        list_add_tail(&ch->stream_list, &oute->outq);
  92}
  93
  94/*
  95 * SFR-CACC algorithm:
  96 * D) If count_of_newacks is greater than or equal to 2
  97 * and t was not sent to the current primary then the
  98 * sender MUST NOT increment missing report count for t.
  99 */
 100static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
 101                                       struct sctp_transport *transport,
 102                                       int count_of_newacks)
 103{
 104        if (count_of_newacks >= 2 && transport != primary)
 105                return 1;
 106        return 0;
 107}
 108
 109/*
 110 * SFR-CACC algorithm:
 111 * F) If count_of_newacks is less than 2, let d be the
 112 * destination to which t was sent. If cacc_saw_newack
 113 * is 0 for destination d, then the sender MUST NOT
 114 * increment missing report count for t.
 115 */
 116static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
 117                                       int count_of_newacks)
 118{
 119        if (count_of_newacks < 2 &&
 120                        (transport && !transport->cacc.cacc_saw_newack))
 121                return 1;
 122        return 0;
 123}
 124
 125/*
 126 * SFR-CACC algorithm:
 127 * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
 128 * execute steps C, D, F.
 129 *
 130 * C has been implemented in sctp_outq_sack
 131 */
 132static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
 133                                     struct sctp_transport *transport,
 134                                     int count_of_newacks)
 135{
 136        if (!primary->cacc.cycling_changeover) {
 137                if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
 138                        return 1;
 139                if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
 140                        return 1;
 141                return 0;
 142        }
 143        return 0;
 144}
 145
 146/*
 147 * SFR-CACC algorithm:
 148 * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
 149 * than next_tsn_at_change of the current primary, then
 150 * the sender MUST NOT increment missing report count
 151 * for t.
 152 */
 153static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
 154{
 155        if (primary->cacc.cycling_changeover &&
 156            TSN_lt(tsn, primary->cacc.next_tsn_at_change))
 157                return 1;
 158        return 0;
 159}
 160
 161/*
 162 * SFR-CACC algorithm:
 163 * 3) If the missing report count for TSN t is to be
 164 * incremented according to [RFC2960] and
 165 * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
 166 * then the sender MUST further execute steps 3.1 and
 167 * 3.2 to determine if the missing report count for
 168 * TSN t SHOULD NOT be incremented.
 169 *
 170 * 3.3) If 3.1 and 3.2 do not dictate that the missing
 171 * report count for t should not be incremented, then
 172 * the sender SHOULD increment missing report count for
 173 * t (according to [RFC2960] and [SCTP_STEWART_2002]).
 174 */
 175static inline int sctp_cacc_skip(struct sctp_transport *primary,
 176                                 struct sctp_transport *transport,
 177                                 int count_of_newacks,
 178                                 __u32 tsn)
 179{
 180        if (primary->cacc.changeover_active &&
 181            (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
 182             sctp_cacc_skip_3_2(primary, tsn)))
 183                return 1;
 184        return 0;
 185}
 186
 187/* Initialize an existing sctp_outq.  This does the boring stuff.
 188 * You still need to define handlers if you really want to DO
 189 * something with this structure...
 190 */
 191void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
 192{
 193        memset(q, 0, sizeof(struct sctp_outq));
 194
 195        q->asoc = asoc;
 196        INIT_LIST_HEAD(&q->out_chunk_list);
 197        INIT_LIST_HEAD(&q->control_chunk_list);
 198        INIT_LIST_HEAD(&q->retransmit);
 199        INIT_LIST_HEAD(&q->sacked);
 200        INIT_LIST_HEAD(&q->abandoned);
 201        sctp_sched_set_sched(asoc, sctp_sk(asoc->base.sk)->default_ss);
 202}
 203
 204/* Free the outqueue structure and any related pending chunks.
 205 */
 206static void __sctp_outq_teardown(struct sctp_outq *q)
 207{
 208        struct sctp_transport *transport;
 209        struct list_head *lchunk, *temp;
 210        struct sctp_chunk *chunk, *tmp;
 211
 212        /* Throw away unacknowledged chunks. */
 213        list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
 214                        transports) {
 215                while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
 216                        chunk = list_entry(lchunk, struct sctp_chunk,
 217                                           transmitted_list);
 218                        /* Mark as part of a failed message. */
 219                        sctp_chunk_fail(chunk, q->error);
 220                        sctp_chunk_free(chunk);
 221                }
 222        }
 223
 224        /* Throw away chunks that have been gap ACKed.  */
 225        list_for_each_safe(lchunk, temp, &q->sacked) {
 226                list_del_init(lchunk);
 227                chunk = list_entry(lchunk, struct sctp_chunk,
 228                                   transmitted_list);
 229                sctp_chunk_fail(chunk, q->error);
 230                sctp_chunk_free(chunk);
 231        }
 232
 233        /* Throw away any chunks in the retransmit queue. */
 234        list_for_each_safe(lchunk, temp, &q->retransmit) {
 235                list_del_init(lchunk);
 236                chunk = list_entry(lchunk, struct sctp_chunk,
 237                                   transmitted_list);
 238                sctp_chunk_fail(chunk, q->error);
 239                sctp_chunk_free(chunk);
 240        }
 241
 242        /* Throw away any chunks that are in the abandoned queue. */
 243        list_for_each_safe(lchunk, temp, &q->abandoned) {
 244                list_del_init(lchunk);
 245                chunk = list_entry(lchunk, struct sctp_chunk,
 246                                   transmitted_list);
 247                sctp_chunk_fail(chunk, q->error);
 248                sctp_chunk_free(chunk);
 249        }
 250
 251        /* Throw away any leftover data chunks. */
 252        while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 253                sctp_sched_dequeue_done(q, chunk);
 254
 255                /* Mark as send failure. */
 256                sctp_chunk_fail(chunk, q->error);
 257                sctp_chunk_free(chunk);
 258        }
 259
 260        /* Throw away any leftover control chunks. */
 261        list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 262                list_del_init(&chunk->list);
 263                sctp_chunk_free(chunk);
 264        }
 265}
 266
 267void sctp_outq_teardown(struct sctp_outq *q)
 268{
 269        __sctp_outq_teardown(q);
 270        sctp_outq_init(q->asoc, q);
 271}
 272
 273/* Free the outqueue structure and any related pending chunks.  */
 274void sctp_outq_free(struct sctp_outq *q)
 275{
 276        /* Throw away leftover chunks. */
 277        __sctp_outq_teardown(q);
 278}
 279
 280/* Put a new chunk in an sctp_outq.  */
 281void sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk, gfp_t gfp)
 282{
 283        struct net *net = q->asoc->base.net;
 284
 285        pr_debug("%s: outq:%p, chunk:%p[%s]\n", __func__, q, chunk,
 286                 chunk && chunk->chunk_hdr ?
 287                 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
 288                 "illegal chunk");
 289
 290        /* If it is data, queue it up, otherwise, send it
 291         * immediately.
 292         */
 293        if (sctp_chunk_is_data(chunk)) {
 294                pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
 295                         __func__, q, chunk, chunk && chunk->chunk_hdr ?
 296                         sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
 297                         "illegal chunk");
 298
 299                sctp_outq_tail_data(q, chunk);
 300                if (chunk->asoc->peer.prsctp_capable &&
 301                    SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
 302                        chunk->asoc->sent_cnt_removable++;
 303                if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
 304                        SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
 305                else
 306                        SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
 307        } else {
 308                list_add_tail(&chunk->list, &q->control_chunk_list);
 309                SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 310        }
 311
 312        if (!q->cork)
 313                sctp_outq_flush(q, 0, gfp);
 314}
 315
 316/* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
 317 * and the abandoned list are in ascending order.
 318 */
 319static void sctp_insert_list(struct list_head *head, struct list_head *new)
 320{
 321        struct list_head *pos;
 322        struct sctp_chunk *nchunk, *lchunk;
 323        __u32 ntsn, ltsn;
 324        int done = 0;
 325
 326        nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
 327        ntsn = ntohl(nchunk->subh.data_hdr->tsn);
 328
 329        list_for_each(pos, head) {
 330                lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
 331                ltsn = ntohl(lchunk->subh.data_hdr->tsn);
 332                if (TSN_lt(ntsn, ltsn)) {
 333                        list_add(new, pos->prev);
 334                        done = 1;
 335                        break;
 336                }
 337        }
 338        if (!done)
 339                list_add_tail(new, head);
 340}
 341
 342static int sctp_prsctp_prune_sent(struct sctp_association *asoc,
 343                                  struct sctp_sndrcvinfo *sinfo,
 344                                  struct list_head *queue, int msg_len)
 345{
 346        struct sctp_chunk *chk, *temp;
 347
 348        list_for_each_entry_safe(chk, temp, queue, transmitted_list) {
 349                struct sctp_stream_out *streamout;
 350
 351                if (!chk->msg->abandoned &&
 352                    (!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
 353                     chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
 354                        continue;
 355
 356                chk->msg->abandoned = 1;
 357                list_del_init(&chk->transmitted_list);
 358                sctp_insert_list(&asoc->outqueue.abandoned,
 359                                 &chk->transmitted_list);
 360
 361                streamout = SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
 362                asoc->sent_cnt_removable--;
 363                asoc->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
 364                streamout->ext->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
 365
 366                if (queue != &asoc->outqueue.retransmit &&
 367                    !chk->tsn_gap_acked) {
 368                        if (chk->transport)
 369                                chk->transport->flight_size -=
 370                                                sctp_data_size(chk);
 371                        asoc->outqueue.outstanding_bytes -= sctp_data_size(chk);
 372                }
 373
 374                msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
 375                if (msg_len <= 0)
 376                        break;
 377        }
 378
 379        return msg_len;
 380}
 381
 382static int sctp_prsctp_prune_unsent(struct sctp_association *asoc,
 383                                    struct sctp_sndrcvinfo *sinfo, int msg_len)
 384{
 385        struct sctp_outq *q = &asoc->outqueue;
 386        struct sctp_chunk *chk, *temp;
 387
 388        q->sched->unsched_all(&asoc->stream);
 389
 390        list_for_each_entry_safe(chk, temp, &q->out_chunk_list, list) {
 391                if (!chk->msg->abandoned &&
 392                    (!(chk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG) ||
 393                     !SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
 394                     chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
 395                        continue;
 396
 397                chk->msg->abandoned = 1;
 398                sctp_sched_dequeue_common(q, chk);
 399                asoc->sent_cnt_removable--;
 400                asoc->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
 401                if (chk->sinfo.sinfo_stream < asoc->stream.outcnt) {
 402                        struct sctp_stream_out *streamout =
 403                                SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
 404
 405                        streamout->ext->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
 406                }
 407
 408                msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
 409                sctp_chunk_free(chk);
 410                if (msg_len <= 0)
 411                        break;
 412        }
 413
 414        q->sched->sched_all(&asoc->stream);
 415
 416        return msg_len;
 417}
 418
 419/* Abandon the chunks according their priorities */
 420void sctp_prsctp_prune(struct sctp_association *asoc,
 421                       struct sctp_sndrcvinfo *sinfo, int msg_len)
 422{
 423        struct sctp_transport *transport;
 424
 425        if (!asoc->peer.prsctp_capable || !asoc->sent_cnt_removable)
 426                return;
 427
 428        msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
 429                                         &asoc->outqueue.retransmit,
 430                                         msg_len);
 431        if (msg_len <= 0)
 432                return;
 433
 434        list_for_each_entry(transport, &asoc->peer.transport_addr_list,
 435                            transports) {
 436                msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
 437                                                 &transport->transmitted,
 438                                                 msg_len);
 439                if (msg_len <= 0)
 440                        return;
 441        }
 442
 443        sctp_prsctp_prune_unsent(asoc, sinfo, msg_len);
 444}
 445
 446/* Mark all the eligible packets on a transport for retransmission.  */
 447void sctp_retransmit_mark(struct sctp_outq *q,
 448                          struct sctp_transport *transport,
 449                          __u8 reason)
 450{
 451        struct list_head *lchunk, *ltemp;
 452        struct sctp_chunk *chunk;
 453
 454        /* Walk through the specified transmitted queue.  */
 455        list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
 456                chunk = list_entry(lchunk, struct sctp_chunk,
 457                                   transmitted_list);
 458
 459                /* If the chunk is abandoned, move it to abandoned list. */
 460                if (sctp_chunk_abandoned(chunk)) {
 461                        list_del_init(lchunk);
 462                        sctp_insert_list(&q->abandoned, lchunk);
 463
 464                        /* If this chunk has not been previousely acked,
 465                         * stop considering it 'outstanding'.  Our peer
 466                         * will most likely never see it since it will
 467                         * not be retransmitted
 468                         */
 469                        if (!chunk->tsn_gap_acked) {
 470                                if (chunk->transport)
 471                                        chunk->transport->flight_size -=
 472                                                        sctp_data_size(chunk);
 473                                q->outstanding_bytes -= sctp_data_size(chunk);
 474                                q->asoc->peer.rwnd += sctp_data_size(chunk);
 475                        }
 476                        continue;
 477                }
 478
 479                /* If we are doing  retransmission due to a timeout or pmtu
 480                 * discovery, only the  chunks that are not yet acked should
 481                 * be added to the retransmit queue.
 482                 */
 483                if ((reason == SCTP_RTXR_FAST_RTX  &&
 484                            (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
 485                    (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
 486                        /* RFC 2960 6.2.1 Processing a Received SACK
 487                         *
 488                         * C) Any time a DATA chunk is marked for
 489                         * retransmission (via either T3-rtx timer expiration
 490                         * (Section 6.3.3) or via fast retransmit
 491                         * (Section 7.2.4)), add the data size of those
 492                         * chunks to the rwnd.
 493                         */
 494                        q->asoc->peer.rwnd += sctp_data_size(chunk);
 495                        q->outstanding_bytes -= sctp_data_size(chunk);
 496                        if (chunk->transport)
 497                                transport->flight_size -= sctp_data_size(chunk);
 498
 499                        /* sctpimpguide-05 Section 2.8.2
 500                         * M5) If a T3-rtx timer expires, the
 501                         * 'TSN.Missing.Report' of all affected TSNs is set
 502                         * to 0.
 503                         */
 504                        chunk->tsn_missing_report = 0;
 505
 506                        /* If a chunk that is being used for RTT measurement
 507                         * has to be retransmitted, we cannot use this chunk
 508                         * anymore for RTT measurements. Reset rto_pending so
 509                         * that a new RTT measurement is started when a new
 510                         * data chunk is sent.
 511                         */
 512                        if (chunk->rtt_in_progress) {
 513                                chunk->rtt_in_progress = 0;
 514                                transport->rto_pending = 0;
 515                        }
 516
 517                        /* Move the chunk to the retransmit queue. The chunks
 518                         * on the retransmit queue are always kept in order.
 519                         */
 520                        list_del_init(lchunk);
 521                        sctp_insert_list(&q->retransmit, lchunk);
 522                }
 523        }
 524
 525        pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, "
 526                 "flight_size:%d, pba:%d\n", __func__, transport, reason,
 527                 transport->cwnd, transport->ssthresh, transport->flight_size,
 528                 transport->partial_bytes_acked);
 529}
 530
 531/* Mark all the eligible packets on a transport for retransmission and force
 532 * one packet out.
 533 */
 534void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
 535                     enum sctp_retransmit_reason reason)
 536{
 537        struct net *net = q->asoc->base.net;
 538
 539        switch (reason) {
 540        case SCTP_RTXR_T3_RTX:
 541                SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
 542                sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
 543                /* Update the retran path if the T3-rtx timer has expired for
 544                 * the current retran path.
 545                 */
 546                if (transport == transport->asoc->peer.retran_path)
 547                        sctp_assoc_update_retran_path(transport->asoc);
 548                transport->asoc->rtx_data_chunks +=
 549                        transport->asoc->unack_data;
 550                break;
 551        case SCTP_RTXR_FAST_RTX:
 552                SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
 553                sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
 554                q->fast_rtx = 1;
 555                break;
 556        case SCTP_RTXR_PMTUD:
 557                SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
 558                break;
 559        case SCTP_RTXR_T1_RTX:
 560                SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
 561                transport->asoc->init_retries++;
 562                break;
 563        default:
 564                BUG();
 565        }
 566
 567        sctp_retransmit_mark(q, transport, reason);
 568
 569        /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
 570         * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
 571         * following the procedures outlined in C1 - C5.
 572         */
 573        if (reason == SCTP_RTXR_T3_RTX)
 574                q->asoc->stream.si->generate_ftsn(q, q->asoc->ctsn_ack_point);
 575
 576        /* Flush the queues only on timeout, since fast_rtx is only
 577         * triggered during sack processing and the queue
 578         * will be flushed at the end.
 579         */
 580        if (reason != SCTP_RTXR_FAST_RTX)
 581                sctp_outq_flush(q, /* rtx_timeout */ 1, GFP_ATOMIC);
 582}
 583
 584/*
 585 * Transmit DATA chunks on the retransmit queue.  Upon return from
 586 * __sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
 587 * need to be transmitted by the caller.
 588 * We assume that pkt->transport has already been set.
 589 *
 590 * The return value is a normal kernel error return value.
 591 */
 592static int __sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 593                                 int rtx_timeout, int *start_timer, gfp_t gfp)
 594{
 595        struct sctp_transport *transport = pkt->transport;
 596        struct sctp_chunk *chunk, *chunk1;
 597        struct list_head *lqueue;
 598        enum sctp_xmit status;
 599        int error = 0;
 600        int timer = 0;
 601        int done = 0;
 602        int fast_rtx;
 603
 604        lqueue = &q->retransmit;
 605        fast_rtx = q->fast_rtx;
 606
 607        /* This loop handles time-out retransmissions, fast retransmissions,
 608         * and retransmissions due to opening of whindow.
 609         *
 610         * RFC 2960 6.3.3 Handle T3-rtx Expiration
 611         *
 612         * E3) Determine how many of the earliest (i.e., lowest TSN)
 613         * outstanding DATA chunks for the address for which the
 614         * T3-rtx has expired will fit into a single packet, subject
 615         * to the MTU constraint for the path corresponding to the
 616         * destination transport address to which the retransmission
 617         * is being sent (this may be different from the address for
 618         * which the timer expires [see Section 6.4]). Call this value
 619         * K. Bundle and retransmit those K DATA chunks in a single
 620         * packet to the destination endpoint.
 621         *
 622         * [Just to be painfully clear, if we are retransmitting
 623         * because a timeout just happened, we should send only ONE
 624         * packet of retransmitted data.]
 625         *
 626         * For fast retransmissions we also send only ONE packet.  However,
 627         * if we are just flushing the queue due to open window, we'll
 628         * try to send as much as possible.
 629         */
 630        list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
 631                /* If the chunk is abandoned, move it to abandoned list. */
 632                if (sctp_chunk_abandoned(chunk)) {
 633                        list_del_init(&chunk->transmitted_list);
 634                        sctp_insert_list(&q->abandoned,
 635                                         &chunk->transmitted_list);
 636                        continue;
 637                }
 638
 639                /* Make sure that Gap Acked TSNs are not retransmitted.  A
 640                 * simple approach is just to move such TSNs out of the
 641                 * way and into a 'transmitted' queue and skip to the
 642                 * next chunk.
 643                 */
 644                if (chunk->tsn_gap_acked) {
 645                        list_move_tail(&chunk->transmitted_list,
 646                                       &transport->transmitted);
 647                        continue;
 648                }
 649
 650                /* If we are doing fast retransmit, ignore non-fast_rtransmit
 651                 * chunks
 652                 */
 653                if (fast_rtx && !chunk->fast_retransmit)
 654                        continue;
 655
 656redo:
 657                /* Attempt to append this chunk to the packet. */
 658                status = sctp_packet_append_chunk(pkt, chunk);
 659
 660                switch (status) {
 661                case SCTP_XMIT_PMTU_FULL:
 662                        if (!pkt->has_data && !pkt->has_cookie_echo) {
 663                                /* If this packet did not contain DATA then
 664                                 * retransmission did not happen, so do it
 665                                 * again.  We'll ignore the error here since
 666                                 * control chunks are already freed so there
 667                                 * is nothing we can do.
 668                                 */
 669                                sctp_packet_transmit(pkt, gfp);
 670                                goto redo;
 671                        }
 672
 673                        /* Send this packet.  */
 674                        error = sctp_packet_transmit(pkt, gfp);
 675
 676                        /* If we are retransmitting, we should only
 677                         * send a single packet.
 678                         * Otherwise, try appending this chunk again.
 679                         */
 680                        if (rtx_timeout || fast_rtx)
 681                                done = 1;
 682                        else
 683                                goto redo;
 684
 685                        /* Bundle next chunk in the next round.  */
 686                        break;
 687
 688                case SCTP_XMIT_RWND_FULL:
 689                        /* Send this packet. */
 690                        error = sctp_packet_transmit(pkt, gfp);
 691
 692                        /* Stop sending DATA as there is no more room
 693                         * at the receiver.
 694                         */
 695                        done = 1;
 696                        break;
 697
 698                case SCTP_XMIT_DELAY:
 699                        /* Send this packet. */
 700                        error = sctp_packet_transmit(pkt, gfp);
 701
 702                        /* Stop sending DATA because of nagle delay. */
 703                        done = 1;
 704                        break;
 705
 706                default:
 707                        /* The append was successful, so add this chunk to
 708                         * the transmitted list.
 709                         */
 710                        list_move_tail(&chunk->transmitted_list,
 711                                       &transport->transmitted);
 712
 713                        /* Mark the chunk as ineligible for fast retransmit
 714                         * after it is retransmitted.
 715                         */
 716                        if (chunk->fast_retransmit == SCTP_NEED_FRTX)
 717                                chunk->fast_retransmit = SCTP_DONT_FRTX;
 718
 719                        q->asoc->stats.rtxchunks++;
 720                        break;
 721                }
 722
 723                /* Set the timer if there were no errors */
 724                if (!error && !timer)
 725                        timer = 1;
 726
 727                if (done)
 728                        break;
 729        }
 730
 731        /* If we are here due to a retransmit timeout or a fast
 732         * retransmit and if there are any chunks left in the retransmit
 733         * queue that could not fit in the PMTU sized packet, they need
 734         * to be marked as ineligible for a subsequent fast retransmit.
 735         */
 736        if (rtx_timeout || fast_rtx) {
 737                list_for_each_entry(chunk1, lqueue, transmitted_list) {
 738                        if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
 739                                chunk1->fast_retransmit = SCTP_DONT_FRTX;
 740                }
 741        }
 742
 743        *start_timer = timer;
 744
 745        /* Clear fast retransmit hint */
 746        if (fast_rtx)
 747                q->fast_rtx = 0;
 748
 749        return error;
 750}
 751
 752/* Cork the outqueue so queued chunks are really queued. */
 753void sctp_outq_uncork(struct sctp_outq *q, gfp_t gfp)
 754{
 755        if (q->cork)
 756                q->cork = 0;
 757
 758        sctp_outq_flush(q, 0, gfp);
 759}
 760
 761static int sctp_packet_singleton(struct sctp_transport *transport,
 762                                 struct sctp_chunk *chunk, gfp_t gfp)
 763{
 764        const struct sctp_association *asoc = transport->asoc;
 765        const __u16 sport = asoc->base.bind_addr.port;
 766        const __u16 dport = asoc->peer.port;
 767        const __u32 vtag = asoc->peer.i.init_tag;
 768        struct sctp_packet singleton;
 769
 770        sctp_packet_init(&singleton, transport, sport, dport);
 771        sctp_packet_config(&singleton, vtag, 0);
 772        if (sctp_packet_append_chunk(&singleton, chunk) != SCTP_XMIT_OK) {
 773                list_del_init(&chunk->list);
 774                sctp_chunk_free(chunk);
 775                return -ENOMEM;
 776        }
 777        return sctp_packet_transmit(&singleton, gfp);
 778}
 779
 780/* Struct to hold the context during sctp outq flush */
 781struct sctp_flush_ctx {
 782        struct sctp_outq *q;
 783        /* Current transport being used. It's NOT the same as curr active one */
 784        struct sctp_transport *transport;
 785        /* These transports have chunks to send. */
 786        struct list_head transport_list;
 787        struct sctp_association *asoc;
 788        /* Packet on the current transport above */
 789        struct sctp_packet *packet;
 790        gfp_t gfp;
 791};
 792
 793/* transport: current transport */
 794static void sctp_outq_select_transport(struct sctp_flush_ctx *ctx,
 795                                       struct sctp_chunk *chunk)
 796{
 797        struct sctp_transport *new_transport = chunk->transport;
 798
 799        if (!new_transport) {
 800                if (!sctp_chunk_is_data(chunk)) {
 801                        /* If we have a prior transport pointer, see if
 802                         * the destination address of the chunk
 803                         * matches the destination address of the
 804                         * current transport.  If not a match, then
 805                         * try to look up the transport with a given
 806                         * destination address.  We do this because
 807                         * after processing ASCONFs, we may have new
 808                         * transports created.
 809                         */
 810                        if (ctx->transport && sctp_cmp_addr_exact(&chunk->dest,
 811                                                        &ctx->transport->ipaddr))
 812                                new_transport = ctx->transport;
 813                        else
 814                                new_transport = sctp_assoc_lookup_paddr(ctx->asoc,
 815                                                                  &chunk->dest);
 816                }
 817
 818                /* if we still don't have a new transport, then
 819                 * use the current active path.
 820                 */
 821                if (!new_transport)
 822                        new_transport = ctx->asoc->peer.active_path;
 823        } else {
 824                __u8 type;
 825
 826                switch (new_transport->state) {
 827                case SCTP_INACTIVE:
 828                case SCTP_UNCONFIRMED:
 829                case SCTP_PF:
 830                        /* If the chunk is Heartbeat or Heartbeat Ack,
 831                         * send it to chunk->transport, even if it's
 832                         * inactive.
 833                         *
 834                         * 3.3.6 Heartbeat Acknowledgement:
 835                         * ...
 836                         * A HEARTBEAT ACK is always sent to the source IP
 837                         * address of the IP datagram containing the
 838                         * HEARTBEAT chunk to which this ack is responding.
 839                         * ...
 840                         *
 841                         * ASCONF_ACKs also must be sent to the source.
 842                         */
 843                        type = chunk->chunk_hdr->type;
 844                        if (type != SCTP_CID_HEARTBEAT &&
 845                            type != SCTP_CID_HEARTBEAT_ACK &&
 846                            type != SCTP_CID_ASCONF_ACK)
 847                                new_transport = ctx->asoc->peer.active_path;
 848                        break;
 849                default:
 850                        break;
 851                }
 852        }
 853
 854        /* Are we switching transports? Take care of transport locks. */
 855        if (new_transport != ctx->transport) {
 856                ctx->transport = new_transport;
 857                ctx->packet = &ctx->transport->packet;
 858
 859                if (list_empty(&ctx->transport->send_ready))
 860                        list_add_tail(&ctx->transport->send_ready,
 861                                      &ctx->transport_list);
 862
 863                sctp_packet_config(ctx->packet,
 864                                   ctx->asoc->peer.i.init_tag,
 865                                   ctx->asoc->peer.ecn_capable);
 866                /* We've switched transports, so apply the
 867                 * Burst limit to the new transport.
 868                 */
 869                sctp_transport_burst_limited(ctx->transport);
 870        }
 871}
 872
 873static void sctp_outq_flush_ctrl(struct sctp_flush_ctx *ctx)
 874{
 875        struct sctp_chunk *chunk, *tmp;
 876        enum sctp_xmit status;
 877        int one_packet, error;
 878
 879        list_for_each_entry_safe(chunk, tmp, &ctx->q->control_chunk_list, list) {
 880                one_packet = 0;
 881
 882                /* RFC 5061, 5.3
 883                 * F1) This means that until such time as the ASCONF
 884                 * containing the add is acknowledged, the sender MUST
 885                 * NOT use the new IP address as a source for ANY SCTP
 886                 * packet except on carrying an ASCONF Chunk.
 887                 */
 888                if (ctx->asoc->src_out_of_asoc_ok &&
 889                    chunk->chunk_hdr->type != SCTP_CID_ASCONF)
 890                        continue;
 891
 892                list_del_init(&chunk->list);
 893
 894                /* Pick the right transport to use. Should always be true for
 895                 * the first chunk as we don't have a transport by then.
 896                 */
 897                sctp_outq_select_transport(ctx, chunk);
 898
 899                switch (chunk->chunk_hdr->type) {
 900                /* 6.10 Bundling
 901                 *   ...
 902                 *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
 903                 *   COMPLETE with any other chunks.  [Send them immediately.]
 904                 */
 905                case SCTP_CID_INIT:
 906                case SCTP_CID_INIT_ACK:
 907                case SCTP_CID_SHUTDOWN_COMPLETE:
 908                        error = sctp_packet_singleton(ctx->transport, chunk,
 909                                                      ctx->gfp);
 910                        if (error < 0) {
 911                                ctx->asoc->base.sk->sk_err = -error;
 912                                return;
 913                        }
 914                        break;
 915
 916                case SCTP_CID_ABORT:
 917                        if (sctp_test_T_bit(chunk))
 918                                ctx->packet->vtag = ctx->asoc->c.my_vtag;
 919                        fallthrough;
 920
 921                /* The following chunks are "response" chunks, i.e.
 922                 * they are generated in response to something we
 923                 * received.  If we are sending these, then we can
 924                 * send only 1 packet containing these chunks.
 925                 */
 926                case SCTP_CID_HEARTBEAT_ACK:
 927                case SCTP_CID_SHUTDOWN_ACK:
 928                case SCTP_CID_COOKIE_ACK:
 929                case SCTP_CID_COOKIE_ECHO:
 930                case SCTP_CID_ERROR:
 931                case SCTP_CID_ECN_CWR:
 932                case SCTP_CID_ASCONF_ACK:
 933                        one_packet = 1;
 934                        fallthrough;
 935
 936                case SCTP_CID_HEARTBEAT:
 937                        if (chunk->pmtu_probe) {
 938                                sctp_packet_singleton(ctx->transport, chunk, ctx->gfp);
 939                                break;
 940                        }
 941                        fallthrough;
 942                case SCTP_CID_SACK:
 943                case SCTP_CID_SHUTDOWN:
 944                case SCTP_CID_ECN_ECNE:
 945                case SCTP_CID_ASCONF:
 946                case SCTP_CID_FWD_TSN:
 947                case SCTP_CID_I_FWD_TSN:
 948                case SCTP_CID_RECONF:
 949                        status = sctp_packet_transmit_chunk(ctx->packet, chunk,
 950                                                            one_packet, ctx->gfp);
 951                        if (status != SCTP_XMIT_OK) {
 952                                /* put the chunk back */
 953                                list_add(&chunk->list, &ctx->q->control_chunk_list);
 954                                break;
 955                        }
 956
 957                        ctx->asoc->stats.octrlchunks++;
 958                        /* PR-SCTP C5) If a FORWARD TSN is sent, the
 959                         * sender MUST assure that at least one T3-rtx
 960                         * timer is running.
 961                         */
 962                        if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN ||
 963                            chunk->chunk_hdr->type == SCTP_CID_I_FWD_TSN) {
 964                                sctp_transport_reset_t3_rtx(ctx->transport);
 965                                ctx->transport->last_time_sent = jiffies;
 966                        }
 967
 968                        if (chunk == ctx->asoc->strreset_chunk)
 969                                sctp_transport_reset_reconf_timer(ctx->transport);
 970
 971                        break;
 972
 973                default:
 974                        /* We built a chunk with an illegal type! */
 975                        BUG();
 976                }
 977        }
 978}
 979
 980/* Returns false if new data shouldn't be sent */
 981static bool sctp_outq_flush_rtx(struct sctp_flush_ctx *ctx,
 982                                int rtx_timeout)
 983{
 984        int error, start_timer = 0;
 985
 986        if (ctx->asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
 987                return false;
 988
 989        if (ctx->transport != ctx->asoc->peer.retran_path) {
 990                /* Switch transports & prepare the packet.  */
 991                ctx->transport = ctx->asoc->peer.retran_path;
 992                ctx->packet = &ctx->transport->packet;
 993
 994                if (list_empty(&ctx->transport->send_ready))
 995                        list_add_tail(&ctx->transport->send_ready,
 996                                      &ctx->transport_list);
 997
 998                sctp_packet_config(ctx->packet, ctx->asoc->peer.i.init_tag,
 999                                   ctx->asoc->peer.ecn_capable);
1000        }
1001
1002        error = __sctp_outq_flush_rtx(ctx->q, ctx->packet, rtx_timeout,
1003                                      &start_timer, ctx->gfp);
1004        if (error < 0)
1005                ctx->asoc->base.sk->sk_err = -error;
1006
1007        if (start_timer) {
1008                sctp_transport_reset_t3_rtx(ctx->transport);
1009                ctx->transport->last_time_sent = jiffies;
1010        }
1011
1012        /* This can happen on COOKIE-ECHO resend.  Only
1013         * one chunk can get bundled with a COOKIE-ECHO.
1014         */
1015        if (ctx->packet->has_cookie_echo)
1016                return false;
1017
1018        /* Don't send new data if there is still data
1019         * waiting to retransmit.
1020         */
1021        if (!list_empty(&ctx->q->retransmit))
1022                return false;
1023
1024        return true;
1025}
1026
1027static void sctp_outq_flush_data(struct sctp_flush_ctx *ctx,
1028                                 int rtx_timeout)
1029{
1030        struct sctp_chunk *chunk;
1031        enum sctp_xmit status;
1032
1033        /* Is it OK to send data chunks?  */
1034        switch (ctx->asoc->state) {
1035        case SCTP_STATE_COOKIE_ECHOED:
1036                /* Only allow bundling when this packet has a COOKIE-ECHO
1037                 * chunk.
1038                 */
1039                if (!ctx->packet || !ctx->packet->has_cookie_echo)
1040                        return;
1041
1042                fallthrough;
1043        case SCTP_STATE_ESTABLISHED:
1044        case SCTP_STATE_SHUTDOWN_PENDING:
1045        case SCTP_STATE_SHUTDOWN_RECEIVED:
1046                break;
1047
1048        default:
1049                /* Do nothing. */
1050                return;
1051        }
1052
1053        /* RFC 2960 6.1  Transmission of DATA Chunks
1054         *
1055         * C) When the time comes for the sender to transmit,
1056         * before sending new DATA chunks, the sender MUST
1057         * first transmit any outstanding DATA chunks which
1058         * are marked for retransmission (limited by the
1059         * current cwnd).
1060         */
1061        if (!list_empty(&ctx->q->retransmit) &&
1062            !sctp_outq_flush_rtx(ctx, rtx_timeout))
1063                return;
1064
1065        /* Apply Max.Burst limitation to the current transport in
1066         * case it will be used for new data.  We are going to
1067         * rest it before we return, but we want to apply the limit
1068         * to the currently queued data.
1069         */
1070        if (ctx->transport)
1071                sctp_transport_burst_limited(ctx->transport);
1072
1073        /* Finally, transmit new packets.  */
1074        while ((chunk = sctp_outq_dequeue_data(ctx->q)) != NULL) {
1075                __u32 sid = ntohs(chunk->subh.data_hdr->stream);
1076                __u8 stream_state = SCTP_SO(&ctx->asoc->stream, sid)->state;
1077
1078                /* Has this chunk expired? */
1079                if (sctp_chunk_abandoned(chunk)) {
1080                        sctp_sched_dequeue_done(ctx->q, chunk);
1081                        sctp_chunk_fail(chunk, 0);
1082                        sctp_chunk_free(chunk);
1083                        continue;
1084                }
1085
1086                if (stream_state == SCTP_STREAM_CLOSED) {
1087                        sctp_outq_head_data(ctx->q, chunk);
1088                        break;
1089                }
1090
1091                sctp_outq_select_transport(ctx, chunk);
1092
1093                pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p skb->users:%d\n",
1094                         __func__, ctx->q, chunk, chunk && chunk->chunk_hdr ?
1095                         sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
1096                         "illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
1097                         chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
1098                         refcount_read(&chunk->skb->users) : -1);
1099
1100                /* Add the chunk to the packet.  */
1101                status = sctp_packet_transmit_chunk(ctx->packet, chunk, 0,
1102                                                    ctx->gfp);
1103                if (status != SCTP_XMIT_OK) {
1104                        /* We could not append this chunk, so put
1105                         * the chunk back on the output queue.
1106                         */
1107                        pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
1108                                 __func__, ntohl(chunk->subh.data_hdr->tsn),
1109                                 status);
1110
1111                        sctp_outq_head_data(ctx->q, chunk);
1112                        break;
1113                }
1114
1115                /* The sender is in the SHUTDOWN-PENDING state,
1116                 * The sender MAY set the I-bit in the DATA
1117                 * chunk header.
1118                 */
1119                if (ctx->asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1120                        chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1121                if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
1122                        ctx->asoc->stats.ouodchunks++;
1123                else
1124                        ctx->asoc->stats.oodchunks++;
1125
1126                /* Only now it's safe to consider this
1127                 * chunk as sent, sched-wise.
1128                 */
1129                sctp_sched_dequeue_done(ctx->q, chunk);
1130
1131                list_add_tail(&chunk->transmitted_list,
1132                              &ctx->transport->transmitted);
1133
1134                sctp_transport_reset_t3_rtx(ctx->transport);
1135                ctx->transport->last_time_sent = jiffies;
1136
1137                /* Only let one DATA chunk get bundled with a
1138                 * COOKIE-ECHO chunk.
1139                 */
1140                if (ctx->packet->has_cookie_echo)
1141                        break;
1142        }
1143}
1144
1145static void sctp_outq_flush_transports(struct sctp_flush_ctx *ctx)
1146{
1147        struct sock *sk = ctx->asoc->base.sk;
1148        struct list_head *ltransport;
1149        struct sctp_packet *packet;
1150        struct sctp_transport *t;
1151        int error = 0;
1152
1153        while ((ltransport = sctp_list_dequeue(&ctx->transport_list)) != NULL) {
1154                t = list_entry(ltransport, struct sctp_transport, send_ready);
1155                packet = &t->packet;
1156                if (!sctp_packet_empty(packet)) {
1157                        rcu_read_lock();
1158                        if (t->dst && __sk_dst_get(sk) != t->dst) {
1159                                dst_hold(t->dst);
1160                                sk_setup_caps(sk, t->dst);
1161                        }
1162                        rcu_read_unlock();
1163                        error = sctp_packet_transmit(packet, ctx->gfp);
1164                        if (error < 0)
1165                                ctx->q->asoc->base.sk->sk_err = -error;
1166                }
1167
1168                /* Clear the burst limited state, if any */
1169                sctp_transport_burst_reset(t);
1170        }
1171}
1172
1173/* Try to flush an outqueue.
1174 *
1175 * Description: Send everything in q which we legally can, subject to
1176 * congestion limitations.
1177 * * Note: This function can be called from multiple contexts so appropriate
1178 * locking concerns must be made.  Today we use the sock lock to protect
1179 * this function.
1180 */
1181
1182static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
1183{
1184        struct sctp_flush_ctx ctx = {
1185                .q = q,
1186                .transport = NULL,
1187                .transport_list = LIST_HEAD_INIT(ctx.transport_list),
1188                .asoc = q->asoc,
1189                .packet = NULL,
1190                .gfp = gfp,
1191        };
1192
1193        /* 6.10 Bundling
1194         *   ...
1195         *   When bundling control chunks with DATA chunks, an
1196         *   endpoint MUST place control chunks first in the outbound
1197         *   SCTP packet.  The transmitter MUST transmit DATA chunks
1198         *   within a SCTP packet in increasing order of TSN.
1199         *   ...
1200         */
1201
1202        sctp_outq_flush_ctrl(&ctx);
1203
1204        if (q->asoc->src_out_of_asoc_ok)
1205                goto sctp_flush_out;
1206
1207        sctp_outq_flush_data(&ctx, rtx_timeout);
1208
1209sctp_flush_out:
1210
1211        sctp_outq_flush_transports(&ctx);
1212}
1213
1214/* Update unack_data based on the incoming SACK chunk */
1215static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1216                                        struct sctp_sackhdr *sack)
1217{
1218        union sctp_sack_variable *frags;
1219        __u16 unack_data;
1220        int i;
1221
1222        unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1223
1224        frags = sack->variable;
1225        for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1226                unack_data -= ((ntohs(frags[i].gab.end) -
1227                                ntohs(frags[i].gab.start) + 1));
1228        }
1229
1230        assoc->unack_data = unack_data;
1231}
1232
1233/* This is where we REALLY process a SACK.
1234 *
1235 * Process the SACK against the outqueue.  Mostly, this just frees
1236 * things off the transmitted queue.
1237 */
1238int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1239{
1240        struct sctp_association *asoc = q->asoc;
1241        struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1242        struct sctp_transport *transport;
1243        struct sctp_chunk *tchunk = NULL;
1244        struct list_head *lchunk, *transport_list, *temp;
1245        union sctp_sack_variable *frags = sack->variable;
1246        __u32 sack_ctsn, ctsn, tsn;
1247        __u32 highest_tsn, highest_new_tsn;
1248        __u32 sack_a_rwnd;
1249        unsigned int outstanding;
1250        struct sctp_transport *primary = asoc->peer.primary_path;
1251        int count_of_newacks = 0;
1252        int gap_ack_blocks;
1253        u8 accum_moved = 0;
1254
1255        /* Grab the association's destination address list. */
1256        transport_list = &asoc->peer.transport_addr_list;
1257
1258        /* SCTP path tracepoint for congestion control debugging. */
1259        if (trace_sctp_probe_path_enabled()) {
1260                list_for_each_entry(transport, transport_list, transports)
1261                        trace_sctp_probe_path(transport, asoc);
1262        }
1263
1264        sack_ctsn = ntohl(sack->cum_tsn_ack);
1265        gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1266        asoc->stats.gapcnt += gap_ack_blocks;
1267        /*
1268         * SFR-CACC algorithm:
1269         * On receipt of a SACK the sender SHOULD execute the
1270         * following statements.
1271         *
1272         * 1) If the cumulative ack in the SACK passes next tsn_at_change
1273         * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1274         * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1275         * all destinations.
1276         * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1277         * is set the receiver of the SACK MUST take the following actions:
1278         *
1279         * A) Initialize the cacc_saw_newack to 0 for all destination
1280         * addresses.
1281         *
1282         * Only bother if changeover_active is set. Otherwise, this is
1283         * totally suboptimal to do on every SACK.
1284         */
1285        if (primary->cacc.changeover_active) {
1286                u8 clear_cycling = 0;
1287
1288                if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1289                        primary->cacc.changeover_active = 0;
1290                        clear_cycling = 1;
1291                }
1292
1293                if (clear_cycling || gap_ack_blocks) {
1294                        list_for_each_entry(transport, transport_list,
1295                                        transports) {
1296                                if (clear_cycling)
1297                                        transport->cacc.cycling_changeover = 0;
1298                                if (gap_ack_blocks)
1299                                        transport->cacc.cacc_saw_newack = 0;
1300                        }
1301                }
1302        }
1303
1304        /* Get the highest TSN in the sack. */
1305        highest_tsn = sack_ctsn;
1306        if (gap_ack_blocks)
1307                highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1308
1309        if (TSN_lt(asoc->highest_sacked, highest_tsn))
1310                asoc->highest_sacked = highest_tsn;
1311
1312        highest_new_tsn = sack_ctsn;
1313
1314        /* Run through the retransmit queue.  Credit bytes received
1315         * and free those chunks that we can.
1316         */
1317        sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1318
1319        /* Run through the transmitted queue.
1320         * Credit bytes received and free those chunks which we can.
1321         *
1322         * This is a MASSIVE candidate for optimization.
1323         */
1324        list_for_each_entry(transport, transport_list, transports) {
1325                sctp_check_transmitted(q, &transport->transmitted,
1326                                       transport, &chunk->source, sack,
1327                                       &highest_new_tsn);
1328                /*
1329                 * SFR-CACC algorithm:
1330                 * C) Let count_of_newacks be the number of
1331                 * destinations for which cacc_saw_newack is set.
1332                 */
1333                if (transport->cacc.cacc_saw_newack)
1334                        count_of_newacks++;
1335        }
1336
1337        /* Move the Cumulative TSN Ack Point if appropriate.  */
1338        if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1339                asoc->ctsn_ack_point = sack_ctsn;
1340                accum_moved = 1;
1341        }
1342
1343        if (gap_ack_blocks) {
1344
1345                if (asoc->fast_recovery && accum_moved)
1346                        highest_new_tsn = highest_tsn;
1347
1348                list_for_each_entry(transport, transport_list, transports)
1349                        sctp_mark_missing(q, &transport->transmitted, transport,
1350                                          highest_new_tsn, count_of_newacks);
1351        }
1352
1353        /* Update unack_data field in the assoc. */
1354        sctp_sack_update_unack_data(asoc, sack);
1355
1356        ctsn = asoc->ctsn_ack_point;
1357
1358        /* Throw away stuff rotting on the sack queue.  */
1359        list_for_each_safe(lchunk, temp, &q->sacked) {
1360                tchunk = list_entry(lchunk, struct sctp_chunk,
1361                                    transmitted_list);
1362                tsn = ntohl(tchunk->subh.data_hdr->tsn);
1363                if (TSN_lte(tsn, ctsn)) {
1364                        list_del_init(&tchunk->transmitted_list);
1365                        if (asoc->peer.prsctp_capable &&
1366                            SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
1367                                asoc->sent_cnt_removable--;
1368                        sctp_chunk_free(tchunk);
1369                }
1370        }
1371
1372        /* ii) Set rwnd equal to the newly received a_rwnd minus the
1373         *     number of bytes still outstanding after processing the
1374         *     Cumulative TSN Ack and the Gap Ack Blocks.
1375         */
1376
1377        sack_a_rwnd = ntohl(sack->a_rwnd);
1378        asoc->peer.zero_window_announced = !sack_a_rwnd;
1379        outstanding = q->outstanding_bytes;
1380
1381        if (outstanding < sack_a_rwnd)
1382                sack_a_rwnd -= outstanding;
1383        else
1384                sack_a_rwnd = 0;
1385
1386        asoc->peer.rwnd = sack_a_rwnd;
1387
1388        asoc->stream.si->generate_ftsn(q, sack_ctsn);
1389
1390        pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
1391        pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
1392                 "advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
1393                 asoc->adv_peer_ack_point);
1394
1395        return sctp_outq_is_empty(q);
1396}
1397
1398/* Is the outqueue empty?
1399 * The queue is empty when we have not pending data, no in-flight data
1400 * and nothing pending retransmissions.
1401 */
1402int sctp_outq_is_empty(const struct sctp_outq *q)
1403{
1404        return q->out_qlen == 0 && q->outstanding_bytes == 0 &&
1405               list_empty(&q->retransmit);
1406}
1407
1408/********************************************************************
1409 * 2nd Level Abstractions
1410 ********************************************************************/
1411
1412/* Go through a transport's transmitted list or the association's retransmit
1413 * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1414 * The retransmit list will not have an associated transport.
1415 *
1416 * I added coherent debug information output.   --xguo
1417 *
1418 * Instead of printing 'sacked' or 'kept' for each TSN on the
1419 * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1420 * KEPT TSN6-TSN7, etc.
1421 */
1422static void sctp_check_transmitted(struct sctp_outq *q,
1423                                   struct list_head *transmitted_queue,
1424                                   struct sctp_transport *transport,
1425                                   union sctp_addr *saddr,
1426                                   struct sctp_sackhdr *sack,
1427                                   __u32 *highest_new_tsn_in_sack)
1428{
1429        struct list_head *lchunk;
1430        struct sctp_chunk *tchunk;
1431        struct list_head tlist;
1432        __u32 tsn;
1433        __u32 sack_ctsn;
1434        __u32 rtt;
1435        __u8 restart_timer = 0;
1436        int bytes_acked = 0;
1437        int migrate_bytes = 0;
1438        bool forward_progress = false;
1439
1440        sack_ctsn = ntohl(sack->cum_tsn_ack);
1441
1442        INIT_LIST_HEAD(&tlist);
1443
1444        /* The while loop will skip empty transmitted queues. */
1445        while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1446                tchunk = list_entry(lchunk, struct sctp_chunk,
1447                                    transmitted_list);
1448
1449                if (sctp_chunk_abandoned(tchunk)) {
1450                        /* Move the chunk to abandoned list. */
1451                        sctp_insert_list(&q->abandoned, lchunk);
1452
1453                        /* If this chunk has not been acked, stop
1454                         * considering it as 'outstanding'.
1455                         */
1456                        if (transmitted_queue != &q->retransmit &&
1457                            !tchunk->tsn_gap_acked) {
1458                                if (tchunk->transport)
1459                                        tchunk->transport->flight_size -=
1460                                                        sctp_data_size(tchunk);
1461                                q->outstanding_bytes -= sctp_data_size(tchunk);
1462                        }
1463                        continue;
1464                }
1465
1466                tsn = ntohl(tchunk->subh.data_hdr->tsn);
1467                if (sctp_acked(sack, tsn)) {
1468                        /* If this queue is the retransmit queue, the
1469                         * retransmit timer has already reclaimed
1470                         * the outstanding bytes for this chunk, so only
1471                         * count bytes associated with a transport.
1472                         */
1473                        if (transport && !tchunk->tsn_gap_acked) {
1474                                /* If this chunk is being used for RTT
1475                                 * measurement, calculate the RTT and update
1476                                 * the RTO using this value.
1477                                 *
1478                                 * 6.3.1 C5) Karn's algorithm: RTT measurements
1479                                 * MUST NOT be made using packets that were
1480                                 * retransmitted (and thus for which it is
1481                                 * ambiguous whether the reply was for the
1482                                 * first instance of the packet or a later
1483                                 * instance).
1484                                 */
1485                                if (!sctp_chunk_retransmitted(tchunk) &&
1486                                    tchunk->rtt_in_progress) {
1487                                        tchunk->rtt_in_progress = 0;
1488                                        rtt = jiffies - tchunk->sent_at;
1489                                        sctp_transport_update_rto(transport,
1490                                                                  rtt);
1491                                }
1492
1493                                if (TSN_lte(tsn, sack_ctsn)) {
1494                                        /*
1495                                         * SFR-CACC algorithm:
1496                                         * 2) If the SACK contains gap acks
1497                                         * and the flag CHANGEOVER_ACTIVE is
1498                                         * set the receiver of the SACK MUST
1499                                         * take the following action:
1500                                         *
1501                                         * B) For each TSN t being acked that
1502                                         * has not been acked in any SACK so
1503                                         * far, set cacc_saw_newack to 1 for
1504                                         * the destination that the TSN was
1505                                         * sent to.
1506                                         */
1507                                        if (sack->num_gap_ack_blocks &&
1508                                            q->asoc->peer.primary_path->cacc.
1509                                            changeover_active)
1510                                                transport->cacc.cacc_saw_newack
1511                                                        = 1;
1512                                }
1513                        }
1514
1515                        /* If the chunk hasn't been marked as ACKED,
1516                         * mark it and account bytes_acked if the
1517                         * chunk had a valid transport (it will not
1518                         * have a transport if ASCONF had deleted it
1519                         * while DATA was outstanding).
1520                         */
1521                        if (!tchunk->tsn_gap_acked) {
1522                                tchunk->tsn_gap_acked = 1;
1523                                if (TSN_lt(*highest_new_tsn_in_sack, tsn))
1524                                        *highest_new_tsn_in_sack = tsn;
1525                                bytes_acked += sctp_data_size(tchunk);
1526                                if (!tchunk->transport)
1527                                        migrate_bytes += sctp_data_size(tchunk);
1528                                forward_progress = true;
1529                        }
1530
1531                        if (TSN_lte(tsn, sack_ctsn)) {
1532                                /* RFC 2960  6.3.2 Retransmission Timer Rules
1533                                 *
1534                                 * R3) Whenever a SACK is received
1535                                 * that acknowledges the DATA chunk
1536                                 * with the earliest outstanding TSN
1537                                 * for that address, restart T3-rtx
1538                                 * timer for that address with its
1539                                 * current RTO.
1540                                 */
1541                                restart_timer = 1;
1542                                forward_progress = true;
1543
1544                                list_add_tail(&tchunk->transmitted_list,
1545                                              &q->sacked);
1546                        } else {
1547                                /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1548                                 * M2) Each time a SACK arrives reporting
1549                                 * 'Stray DATA chunk(s)' record the highest TSN
1550                                 * reported as newly acknowledged, call this
1551                                 * value 'HighestTSNinSack'. A newly
1552                                 * acknowledged DATA chunk is one not
1553                                 * previously acknowledged in a SACK.
1554                                 *
1555                                 * When the SCTP sender of data receives a SACK
1556                                 * chunk that acknowledges, for the first time,
1557                                 * the receipt of a DATA chunk, all the still
1558                                 * unacknowledged DATA chunks whose TSN is
1559                                 * older than that newly acknowledged DATA
1560                                 * chunk, are qualified as 'Stray DATA chunks'.
1561                                 */
1562                                list_add_tail(lchunk, &tlist);
1563                        }
1564                } else {
1565                        if (tchunk->tsn_gap_acked) {
1566                                pr_debug("%s: receiver reneged on data TSN:0x%x\n",
1567                                         __func__, tsn);
1568
1569                                tchunk->tsn_gap_acked = 0;
1570
1571                                if (tchunk->transport)
1572                                        bytes_acked -= sctp_data_size(tchunk);
1573
1574                                /* RFC 2960 6.3.2 Retransmission Timer Rules
1575                                 *
1576                                 * R4) Whenever a SACK is received missing a
1577                                 * TSN that was previously acknowledged via a
1578                                 * Gap Ack Block, start T3-rtx for the
1579                                 * destination address to which the DATA
1580                                 * chunk was originally
1581                                 * transmitted if it is not already running.
1582                                 */
1583                                restart_timer = 1;
1584                        }
1585
1586                        list_add_tail(lchunk, &tlist);
1587                }
1588        }
1589
1590        if (transport) {
1591                if (bytes_acked) {
1592                        struct sctp_association *asoc = transport->asoc;
1593
1594                        /* We may have counted DATA that was migrated
1595                         * to this transport due to DEL-IP operation.
1596                         * Subtract those bytes, since the were never
1597                         * send on this transport and shouldn't be
1598                         * credited to this transport.
1599                         */
1600                        bytes_acked -= migrate_bytes;
1601
1602                        /* 8.2. When an outstanding TSN is acknowledged,
1603                         * the endpoint shall clear the error counter of
1604                         * the destination transport address to which the
1605                         * DATA chunk was last sent.
1606                         * The association's overall error counter is
1607                         * also cleared.
1608                         */
1609                        transport->error_count = 0;
1610                        transport->asoc->overall_error_count = 0;
1611                        forward_progress = true;
1612
1613                        /*
1614                         * While in SHUTDOWN PENDING, we may have started
1615                         * the T5 shutdown guard timer after reaching the
1616                         * retransmission limit. Stop that timer as soon
1617                         * as the receiver acknowledged any data.
1618                         */
1619                        if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1620                            del_timer(&asoc->timers
1621                                [SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1622                                        sctp_association_put(asoc);
1623
1624                        /* Mark the destination transport address as
1625                         * active if it is not so marked.
1626                         */
1627                        if ((transport->state == SCTP_INACTIVE ||
1628                             transport->state == SCTP_UNCONFIRMED) &&
1629                            sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1630                                sctp_assoc_control_transport(
1631                                        transport->asoc,
1632                                        transport,
1633                                        SCTP_TRANSPORT_UP,
1634                                        SCTP_RECEIVED_SACK);
1635                        }
1636
1637                        sctp_transport_raise_cwnd(transport, sack_ctsn,
1638                                                  bytes_acked);
1639
1640                        transport->flight_size -= bytes_acked;
1641                        if (transport->flight_size == 0)
1642                                transport->partial_bytes_acked = 0;
1643                        q->outstanding_bytes -= bytes_acked + migrate_bytes;
1644                } else {
1645                        /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1646                         * When a sender is doing zero window probing, it
1647                         * should not timeout the association if it continues
1648                         * to receive new packets from the receiver. The
1649                         * reason is that the receiver MAY keep its window
1650                         * closed for an indefinite time.
1651                         * A sender is doing zero window probing when the
1652                         * receiver's advertised window is zero, and there is
1653                         * only one data chunk in flight to the receiver.
1654                         *
1655                         * Allow the association to timeout while in SHUTDOWN
1656                         * PENDING or SHUTDOWN RECEIVED in case the receiver
1657                         * stays in zero window mode forever.
1658                         */
1659                        if (!q->asoc->peer.rwnd &&
1660                            !list_empty(&tlist) &&
1661                            (sack_ctsn+2 == q->asoc->next_tsn) &&
1662                            q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1663                                pr_debug("%s: sack received for zero window "
1664                                         "probe:%u\n", __func__, sack_ctsn);
1665
1666                                q->asoc->overall_error_count = 0;
1667                                transport->error_count = 0;
1668                        }
1669                }
1670
1671                /* RFC 2960 6.3.2 Retransmission Timer Rules
1672                 *
1673                 * R2) Whenever all outstanding data sent to an address have
1674                 * been acknowledged, turn off the T3-rtx timer of that
1675                 * address.
1676                 */
1677                if (!transport->flight_size) {
1678                        if (del_timer(&transport->T3_rtx_timer))
1679                                sctp_transport_put(transport);
1680                } else if (restart_timer) {
1681                        if (!mod_timer(&transport->T3_rtx_timer,
1682                                       jiffies + transport->rto))
1683                                sctp_transport_hold(transport);
1684                }
1685
1686                if (forward_progress) {
1687                        if (transport->dst)
1688                                sctp_transport_dst_confirm(transport);
1689                }
1690        }
1691
1692        list_splice(&tlist, transmitted_queue);
1693}
1694
1695/* Mark chunks as missing and consequently may get retransmitted. */
1696static void sctp_mark_missing(struct sctp_outq *q,
1697                              struct list_head *transmitted_queue,
1698                              struct sctp_transport *transport,
1699                              __u32 highest_new_tsn_in_sack,
1700                              int count_of_newacks)
1701{
1702        struct sctp_chunk *chunk;
1703        __u32 tsn;
1704        char do_fast_retransmit = 0;
1705        struct sctp_association *asoc = q->asoc;
1706        struct sctp_transport *primary = asoc->peer.primary_path;
1707
1708        list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1709
1710                tsn = ntohl(chunk->subh.data_hdr->tsn);
1711
1712                /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1713                 * 'Unacknowledged TSN's', if the TSN number of an
1714                 * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1715                 * value, increment the 'TSN.Missing.Report' count on that
1716                 * chunk if it has NOT been fast retransmitted or marked for
1717                 * fast retransmit already.
1718                 */
1719                if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1720                    !chunk->tsn_gap_acked &&
1721                    TSN_lt(tsn, highest_new_tsn_in_sack)) {
1722
1723                        /* SFR-CACC may require us to skip marking
1724                         * this chunk as missing.
1725                         */
1726                        if (!transport || !sctp_cacc_skip(primary,
1727                                                chunk->transport,
1728                                                count_of_newacks, tsn)) {
1729                                chunk->tsn_missing_report++;
1730
1731                                pr_debug("%s: tsn:0x%x missing counter:%d\n",
1732                                         __func__, tsn, chunk->tsn_missing_report);
1733                        }
1734                }
1735                /*
1736                 * M4) If any DATA chunk is found to have a
1737                 * 'TSN.Missing.Report'
1738                 * value larger than or equal to 3, mark that chunk for
1739                 * retransmission and start the fast retransmit procedure.
1740                 */
1741
1742                if (chunk->tsn_missing_report >= 3) {
1743                        chunk->fast_retransmit = SCTP_NEED_FRTX;
1744                        do_fast_retransmit = 1;
1745                }
1746        }
1747
1748        if (transport) {
1749                if (do_fast_retransmit)
1750                        sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1751
1752                pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
1753                         "flight_size:%d, pba:%d\n",  __func__, transport,
1754                         transport->cwnd, transport->ssthresh,
1755                         transport->flight_size, transport->partial_bytes_acked);
1756        }
1757}
1758
1759/* Is the given TSN acked by this packet?  */
1760static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1761{
1762        __u32 ctsn = ntohl(sack->cum_tsn_ack);
1763        union sctp_sack_variable *frags;
1764        __u16 tsn_offset, blocks;
1765        int i;
1766
1767        if (TSN_lte(tsn, ctsn))
1768                goto pass;
1769
1770        /* 3.3.4 Selective Acknowledgment (SACK) (3):
1771         *
1772         * Gap Ack Blocks:
1773         *  These fields contain the Gap Ack Blocks. They are repeated
1774         *  for each Gap Ack Block up to the number of Gap Ack Blocks
1775         *  defined in the Number of Gap Ack Blocks field. All DATA
1776         *  chunks with TSNs greater than or equal to (Cumulative TSN
1777         *  Ack + Gap Ack Block Start) and less than or equal to
1778         *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1779         *  Block are assumed to have been received correctly.
1780         */
1781
1782        frags = sack->variable;
1783        blocks = ntohs(sack->num_gap_ack_blocks);
1784        tsn_offset = tsn - ctsn;
1785        for (i = 0; i < blocks; ++i) {
1786                if (tsn_offset >= ntohs(frags[i].gab.start) &&
1787                    tsn_offset <= ntohs(frags[i].gab.end))
1788                        goto pass;
1789        }
1790
1791        return 0;
1792pass:
1793        return 1;
1794}
1795
1796static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1797                                    int nskips, __be16 stream)
1798{
1799        int i;
1800
1801        for (i = 0; i < nskips; i++) {
1802                if (skiplist[i].stream == stream)
1803                        return i;
1804        }
1805        return i;
1806}
1807
1808/* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1809void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1810{
1811        struct sctp_association *asoc = q->asoc;
1812        struct sctp_chunk *ftsn_chunk = NULL;
1813        struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1814        int nskips = 0;
1815        int skip_pos = 0;
1816        __u32 tsn;
1817        struct sctp_chunk *chunk;
1818        struct list_head *lchunk, *temp;
1819
1820        if (!asoc->peer.prsctp_capable)
1821                return;
1822
1823        /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1824         * received SACK.
1825         *
1826         * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1827         * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1828         */
1829        if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1830                asoc->adv_peer_ack_point = ctsn;
1831
1832        /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1833         * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1834         * the chunk next in the out-queue space is marked as "abandoned" as
1835         * shown in the following example:
1836         *
1837         * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1838         * and the Advanced.Peer.Ack.Point is updated to this value:
1839         *
1840         *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1841         *   normal SACK processing           local advancement
1842         *                ...                           ...
1843         *   Adv.Ack.Pt-> 102 acked                     102 acked
1844         *                103 abandoned                 103 abandoned
1845         *                104 abandoned     Adv.Ack.P-> 104 abandoned
1846         *                105                           105
1847         *                106 acked                     106 acked
1848         *                ...                           ...
1849         *
1850         * In this example, the data sender successfully advanced the
1851         * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1852         */
1853        list_for_each_safe(lchunk, temp, &q->abandoned) {
1854                chunk = list_entry(lchunk, struct sctp_chunk,
1855                                        transmitted_list);
1856                tsn = ntohl(chunk->subh.data_hdr->tsn);
1857
1858                /* Remove any chunks in the abandoned queue that are acked by
1859                 * the ctsn.
1860                 */
1861                if (TSN_lte(tsn, ctsn)) {
1862                        list_del_init(lchunk);
1863                        sctp_chunk_free(chunk);
1864                } else {
1865                        if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1866                                asoc->adv_peer_ack_point = tsn;
1867                                if (chunk->chunk_hdr->flags &
1868                                         SCTP_DATA_UNORDERED)
1869                                        continue;
1870                                skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1871                                                nskips,
1872                                                chunk->subh.data_hdr->stream);
1873                                ftsn_skip_arr[skip_pos].stream =
1874                                        chunk->subh.data_hdr->stream;
1875                                ftsn_skip_arr[skip_pos].ssn =
1876                                         chunk->subh.data_hdr->ssn;
1877                                if (skip_pos == nskips)
1878                                        nskips++;
1879                                if (nskips == 10)
1880                                        break;
1881                        } else
1882                                break;
1883                }
1884        }
1885
1886        /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1887         * is greater than the Cumulative TSN ACK carried in the received
1888         * SACK, the data sender MUST send the data receiver a FORWARD TSN
1889         * chunk containing the latest value of the
1890         * "Advanced.Peer.Ack.Point".
1891         *
1892         * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1893         * list each stream and sequence number in the forwarded TSN. This
1894         * information will enable the receiver to easily find any
1895         * stranded TSN's waiting on stream reorder queues. Each stream
1896         * SHOULD only be reported once; this means that if multiple
1897         * abandoned messages occur in the same stream then only the
1898         * highest abandoned stream sequence number is reported. If the
1899         * total size of the FORWARD TSN does NOT fit in a single MTU then
1900         * the sender of the FORWARD TSN SHOULD lower the
1901         * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1902         * single MTU.
1903         */
1904        if (asoc->adv_peer_ack_point > ctsn)
1905                ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1906                                              nskips, &ftsn_skip_arr[0]);
1907
1908        if (ftsn_chunk) {
1909                list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1910                SCTP_INC_STATS(asoc->base.net, SCTP_MIB_OUTCTRLCHUNKS);
1911        }
1912}
1913
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