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. */ 42 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn); 43 static 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 50 static 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 56 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp); 57 58 /* Add data to the front of the queue. */ 59 static 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. */ 74 static 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. */ 80 static 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 */ 100 static 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 */ 116 static 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 */ 132 static 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 */ 153 static 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 */ 175 static 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 */ 191 void 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 */ 206 static 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 } 266 267 void 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. */ 274 void 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. */ 281 void 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 */ 319 static 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 } 341 342 static 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 } 381 382 static 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 struct sctp_stream_out *sout; 388 389 q->sched->unsched_all(&asoc->stream); 390 391 list_for_each_entry_safe(chk, temp, &q->out_chunk_list, list) { 392 if (!chk->msg->abandoned && 393 (!(chk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG) || 394 !SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) || 395 chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive)) 396 continue; 397 398 chk->msg->abandoned = 1; 399 sctp_sched_dequeue_common(q, chk); 400 asoc->sent_cnt_removable--; 401 asoc->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++; 402 403 sout = SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream); 404 sout->ext->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++; 405 406 /* clear out_curr if all frag chunks are pruned */ 407 if (asoc->stream.out_curr == sout && 408 list_is_last(&chk->frag_list, &chk->msg->chunks)) 409 asoc->stream.out_curr = NULL; 410 411 msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk); 412 sctp_chunk_free(chk); 413 if (msg_len <= 0) 414 break; 415 } 416 417 q->sched->sched_all(&asoc->stream); 418 419 return msg_len; 420 } 421 422 /* Abandon the chunks according their priorities */ 423 void sctp_prsctp_prune(struct sctp_association *asoc, 424 struct sctp_sndrcvinfo *sinfo, int msg_len) 425 { 426 struct sctp_transport *transport; 427 428 if (!asoc->peer.prsctp_capable || !asoc->sent_cnt_removable) 429 return; 430 431 msg_len = sctp_prsctp_prune_sent(asoc, sinfo, 432 &asoc->outqueue.retransmit, 433 msg_len); 434 if (msg_len <= 0) 435 return; 436 437 list_for_each_entry(transport, &asoc->peer.transport_addr_list, 438 transports) { 439 msg_len = sctp_prsctp_prune_sent(asoc, sinfo, 440 &transport->transmitted, 441 msg_len); 442 if (msg_len <= 0) 443 return; 444 } 445 446 sctp_prsctp_prune_unsent(asoc, sinfo, msg_len); 447 } 448 449 /* Mark all the eligible packets on a transport for retransmission. */ 450 void sctp_retransmit_mark(struct sctp_outq *q, 451 struct sctp_transport *transport, 452 __u8 reason) 453 { 454 struct list_head *lchunk, *ltemp; 455 struct sctp_chunk *chunk; 456 457 /* Walk through the specified transmitted queue. */ 458 list_for_each_safe(lchunk, ltemp, &transport->transmitted) { 459 chunk = list_entry(lchunk, struct sctp_chunk, 460 transmitted_list); 461 462 /* If the chunk is abandoned, move it to abandoned list. */ 463 if (sctp_chunk_abandoned(chunk)) { 464 list_del_init(lchunk); 465 sctp_insert_list(&q->abandoned, lchunk); 466 467 /* If this chunk has not been previousely acked, 468 * stop considering it 'outstanding'. Our peer 469 * will most likely never see it since it will 470 * not be retransmitted 471 */ 472 if (!chunk->tsn_gap_acked) { 473 if (chunk->transport) 474 chunk->transport->flight_size -= 475 sctp_data_size(chunk); 476 q->outstanding_bytes -= sctp_data_size(chunk); 477 q->asoc->peer.rwnd += sctp_data_size(chunk); 478 } 479 continue; 480 } 481 482 /* If we are doing retransmission due to a timeout or pmtu 483 * discovery, only the chunks that are not yet acked should 484 * be added to the retransmit queue. 485 */ 486 if ((reason == SCTP_RTXR_FAST_RTX && 487 (chunk->fast_retransmit == SCTP_NEED_FRTX)) || 488 (reason != SCTP_RTXR_FAST_RTX && !chunk->tsn_gap_acked)) { 489 /* RFC 2960 6.2.1 Processing a Received SACK 490 * 491 * C) Any time a DATA chunk is marked for 492 * retransmission (via either T3-rtx timer expiration 493 * (Section 6.3.3) or via fast retransmit 494 * (Section 7.2.4)), add the data size of those 495 * chunks to the rwnd. 496 */ 497 q->asoc->peer.rwnd += sctp_data_size(chunk); 498 q->outstanding_bytes -= sctp_data_size(chunk); 499 if (chunk->transport) 500 transport->flight_size -= sctp_data_size(chunk); 501 502 /* sctpimpguide-05 Section 2.8.2 503 * M5) If a T3-rtx timer expires, the 504 * 'TSN.Missing.Report' of all affected TSNs is set 505 * to 0. 506 */ 507 chunk->tsn_missing_report = 0; 508 509 /* If a chunk that is being used for RTT measurement 510 * has to be retransmitted, we cannot use this chunk 511 * anymore for RTT measurements. Reset rto_pending so 512 * that a new RTT measurement is started when a new 513 * data chunk is sent. 514 */ 515 if (chunk->rtt_in_progress) { 516 chunk->rtt_in_progress = 0; 517 transport->rto_pending = 0; 518 } 519 520 /* Move the chunk to the retransmit queue. The chunks 521 * on the retransmit queue are always kept in order. 522 */ 523 list_del_init(lchunk); 524 sctp_insert_list(&q->retransmit, lchunk); 525 } 526 } 527 528 pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, " 529 "flight_size:%d, pba:%d\n", __func__, transport, reason, 530 transport->cwnd, transport->ssthresh, transport->flight_size, 531 transport->partial_bytes_acked); 532 } 533 534 /* Mark all the eligible packets on a transport for retransmission and force 535 * one packet out. 536 */ 537 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport, 538 enum sctp_retransmit_reason reason) 539 { 540 struct net *net = q->asoc->base.net; 541 542 switch (reason) { 543 case SCTP_RTXR_T3_RTX: 544 SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS); 545 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX); 546 /* Update the retran path if the T3-rtx timer has expired for 547 * the current retran path. 548 */ 549 if (transport == transport->asoc->peer.retran_path) 550 sctp_assoc_update_retran_path(transport->asoc); 551 transport->asoc->rtx_data_chunks += 552 transport->asoc->unack_data; 553 if (transport->pl.state == SCTP_PL_COMPLETE && 554 transport->asoc->unack_data) 555 sctp_transport_reset_probe_timer(transport); 556 break; 557 case SCTP_RTXR_FAST_RTX: 558 SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS); 559 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX); 560 q->fast_rtx = 1; 561 break; 562 case SCTP_RTXR_PMTUD: 563 SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS); 564 break; 565 case SCTP_RTXR_T1_RTX: 566 SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS); 567 transport->asoc->init_retries++; 568 break; 569 default: 570 BUG(); 571 } 572 573 sctp_retransmit_mark(q, transport, reason); 574 575 /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination, 576 * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by 577 * following the procedures outlined in C1 - C5. 578 */ 579 if (reason == SCTP_RTXR_T3_RTX) 580 q->asoc->stream.si->generate_ftsn(q, q->asoc->ctsn_ack_point); 581 582 /* Flush the queues only on timeout, since fast_rtx is only 583 * triggered during sack processing and the queue 584 * will be flushed at the end. 585 */ 586 if (reason != SCTP_RTXR_FAST_RTX) 587 sctp_outq_flush(q, /* rtx_timeout */ 1, GFP_ATOMIC); 588 } 589 590 /* 591 * Transmit DATA chunks on the retransmit queue. Upon return from 592 * __sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which 593 * need to be transmitted by the caller. 594 * We assume that pkt->transport has already been set. 595 * 596 * The return value is a normal kernel error return value. 597 */ 598 static int __sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt, 599 int rtx_timeout, int *start_timer, gfp_t gfp) 600 { 601 struct sctp_transport *transport = pkt->transport; 602 struct sctp_chunk *chunk, *chunk1; 603 struct list_head *lqueue; 604 enum sctp_xmit status; 605 int error = 0; 606 int timer = 0; 607 int done = 0; 608 int fast_rtx; 609 610 lqueue = &q->retransmit; 611 fast_rtx = q->fast_rtx; 612 613 /* This loop handles time-out retransmissions, fast retransmissions, 614 * and retransmissions due to opening of whindow. 615 * 616 * RFC 2960 6.3.3 Handle T3-rtx Expiration 617 * 618 * E3) Determine how many of the earliest (i.e., lowest TSN) 619 * outstanding DATA chunks for the address for which the 620 * T3-rtx has expired will fit into a single packet, subject 621 * to the MTU constraint for the path corresponding to the 622 * destination transport address to which the retransmission 623 * is being sent (this may be different from the address for 624 * which the timer expires [see Section 6.4]). Call this value 625 * K. Bundle and retransmit those K DATA chunks in a single 626 * packet to the destination endpoint. 627 * 628 * [Just to be painfully clear, if we are retransmitting 629 * because a timeout just happened, we should send only ONE 630 * packet of retransmitted data.] 631 * 632 * For fast retransmissions we also send only ONE packet. However, 633 * if we are just flushing the queue due to open window, we'll 634 * try to send as much as possible. 635 */ 636 list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) { 637 /* If the chunk is abandoned, move it to abandoned list. */ 638 if (sctp_chunk_abandoned(chunk)) { 639 list_del_init(&chunk->transmitted_list); 640 sctp_insert_list(&q->abandoned, 641 &chunk->transmitted_list); 642 continue; 643 } 644 645 /* Make sure that Gap Acked TSNs are not retransmitted. A 646 * simple approach is just to move such TSNs out of the 647 * way and into a 'transmitted' queue and skip to the 648 * next chunk. 649 */ 650 if (chunk->tsn_gap_acked) { 651 list_move_tail(&chunk->transmitted_list, 652 &transport->transmitted); 653 chunk->transport = transport; 654 continue; 655 } 656 657 /* If we are doing fast retransmit, ignore non-fast_rtransmit 658 * chunks 659 */ 660 if (fast_rtx && !chunk->fast_retransmit) 661 continue; 662 663 redo: 664 /* Attempt to append this chunk to the packet. */ 665 status = sctp_packet_append_chunk(pkt, chunk); 666 667 switch (status) { 668 case SCTP_XMIT_PMTU_FULL: 669 if (!pkt->has_data && !pkt->has_cookie_echo) { 670 /* If this packet did not contain DATA then 671 * retransmission did not happen, so do it 672 * again. We'll ignore the error here since 673 * control chunks are already freed so there 674 * is nothing we can do. 675 */ 676 sctp_packet_transmit(pkt, gfp); 677 goto redo; 678 } 679 680 /* Send this packet. */ 681 error = sctp_packet_transmit(pkt, gfp); 682 683 /* If we are retransmitting, we should only 684 * send a single packet. 685 * Otherwise, try appending this chunk again. 686 */ 687 if (rtx_timeout || fast_rtx) 688 done = 1; 689 else 690 goto redo; 691 692 /* Bundle next chunk in the next round. */ 693 break; 694 695 case SCTP_XMIT_RWND_FULL: 696 /* Send this packet. */ 697 error = sctp_packet_transmit(pkt, gfp); 698 699 /* Stop sending DATA as there is no more room 700 * at the receiver. 701 */ 702 done = 1; 703 break; 704 705 case SCTP_XMIT_DELAY: 706 /* Send this packet. */ 707 error = sctp_packet_transmit(pkt, gfp); 708 709 /* Stop sending DATA because of nagle delay. */ 710 done = 1; 711 break; 712 713 default: 714 /* The append was successful, so add this chunk to 715 * the transmitted list. 716 */ 717 list_move_tail(&chunk->transmitted_list, 718 &transport->transmitted); 719 720 /* Mark the chunk as ineligible for fast retransmit 721 * after it is retransmitted. 722 */ 723 if (chunk->fast_retransmit == SCTP_NEED_FRTX) 724 chunk->fast_retransmit = SCTP_DONT_FRTX; 725 726 q->asoc->stats.rtxchunks++; 727 break; 728 } 729 730 /* Set the timer if there were no errors */ 731 if (!error && !timer) 732 timer = 1; 733 734 if (done) 735 break; 736 } 737 738 /* If we are here due to a retransmit timeout or a fast 739 * retransmit and if there are any chunks left in the retransmit 740 * queue that could not fit in the PMTU sized packet, they need 741 * to be marked as ineligible for a subsequent fast retransmit. 742 */ 743 if (rtx_timeout || fast_rtx) { 744 list_for_each_entry(chunk1, lqueue, transmitted_list) { 745 if (chunk1->fast_retransmit == SCTP_NEED_FRTX) 746 chunk1->fast_retransmit = SCTP_DONT_FRTX; 747 } 748 } 749 750 *start_timer = timer; 751 752 /* Clear fast retransmit hint */ 753 if (fast_rtx) 754 q->fast_rtx = 0; 755 756 return error; 757 } 758 759 /* Cork the outqueue so queued chunks are really queued. */ 760 void sctp_outq_uncork(struct sctp_outq *q, gfp_t gfp) 761 { 762 if (q->cork) 763 q->cork = 0; 764 765 sctp_outq_flush(q, 0, gfp); 766 } 767 768 static int sctp_packet_singleton(struct sctp_transport *transport, 769 struct sctp_chunk *chunk, gfp_t gfp) 770 { 771 const struct sctp_association *asoc = transport->asoc; 772 const __u16 sport = asoc->base.bind_addr.port; 773 const __u16 dport = asoc->peer.port; 774 const __u32 vtag = asoc->peer.i.init_tag; 775 struct sctp_packet singleton; 776 777 sctp_packet_init(&singleton, transport, sport, dport); 778 sctp_packet_config(&singleton, vtag, 0); 779 if (sctp_packet_append_chunk(&singleton, chunk) != SCTP_XMIT_OK) { 780 list_del_init(&chunk->list); 781 sctp_chunk_free(chunk); 782 return -ENOMEM; 783 } 784 return sctp_packet_transmit(&singleton, gfp); 785 } 786 787 /* Struct to hold the context during sctp outq flush */ 788 struct sctp_flush_ctx { 789 struct sctp_outq *q; 790 /* Current transport being used. It's NOT the same as curr active one */ 791 struct sctp_transport *transport; 792 /* These transports have chunks to send. */ 793 struct list_head transport_list; 794 struct sctp_association *asoc; 795 /* Packet on the current transport above */ 796 struct sctp_packet *packet; 797 gfp_t gfp; 798 }; 799 800 /* transport: current transport */ 801 static void sctp_outq_select_transport(struct sctp_flush_ctx *ctx, 802 struct sctp_chunk *chunk) 803 { 804 struct sctp_transport *new_transport = chunk->transport; 805 806 if (!new_transport) { 807 if (!sctp_chunk_is_data(chunk)) { 808 /* If we have a prior transport pointer, see if 809 * the destination address of the chunk 810 * matches the destination address of the 811 * current transport. If not a match, then 812 * try to look up the transport with a given 813 * destination address. We do this because 814 * after processing ASCONFs, we may have new 815 * transports created. 816 */ 817 if (ctx->transport && sctp_cmp_addr_exact(&chunk->dest, 818 &ctx->transport->ipaddr)) 819 new_transport = ctx->transport; 820 else 821 new_transport = sctp_assoc_lookup_paddr(ctx->asoc, 822 &chunk->dest); 823 } 824 825 /* if we still don't have a new transport, then 826 * use the current active path. 827 */ 828 if (!new_transport) 829 new_transport = ctx->asoc->peer.active_path; 830 } else { 831 __u8 type; 832 833 switch (new_transport->state) { 834 case SCTP_INACTIVE: 835 case SCTP_UNCONFIRMED: 836 case SCTP_PF: 837 /* If the chunk is Heartbeat or Heartbeat Ack, 838 * send it to chunk->transport, even if it's 839 * inactive. 840 * 841 * 3.3.6 Heartbeat Acknowledgement: 842 * ... 843 * A HEARTBEAT ACK is always sent to the source IP 844 * address of the IP datagram containing the 845 * HEARTBEAT chunk to which this ack is responding. 846 * ... 847 * 848 * ASCONF_ACKs also must be sent to the source. 849 */ 850 type = chunk->chunk_hdr->type; 851 if (type != SCTP_CID_HEARTBEAT && 852 type != SCTP_CID_HEARTBEAT_ACK && 853 type != SCTP_CID_ASCONF_ACK) 854 new_transport = ctx->asoc->peer.active_path; 855 break; 856 default: 857 break; 858 } 859 } 860 861 /* Are we switching transports? Take care of transport locks. */ 862 if (new_transport != ctx->transport) { 863 ctx->transport = new_transport; 864 ctx->packet = &ctx->transport->packet; 865 866 if (list_empty(&ctx->transport->send_ready)) 867 list_add_tail(&ctx->transport->send_ready, 868 &ctx->transport_list); 869 870 sctp_packet_config(ctx->packet, 871 ctx->asoc->peer.i.init_tag, 872 ctx->asoc->peer.ecn_capable); 873 /* We've switched transports, so apply the 874 * Burst limit to the new transport. 875 */ 876 sctp_transport_burst_limited(ctx->transport); 877 } 878 } 879 880 static void sctp_outq_flush_ctrl(struct sctp_flush_ctx *ctx) 881 { 882 struct sctp_chunk *chunk, *tmp; 883 enum sctp_xmit status; 884 int one_packet, error; 885 886 list_for_each_entry_safe(chunk, tmp, &ctx->q->control_chunk_list, list) { 887 one_packet = 0; 888 889 /* RFC 5061, 5.3 890 * F1) This means that until such time as the ASCONF 891 * containing the add is acknowledged, the sender MUST 892 * NOT use the new IP address as a source for ANY SCTP 893 * packet except on carrying an ASCONF Chunk. 894 */ 895 if (ctx->asoc->src_out_of_asoc_ok && 896 chunk->chunk_hdr->type != SCTP_CID_ASCONF) 897 continue; 898 899 list_del_init(&chunk->list); 900 901 /* Pick the right transport to use. Should always be true for 902 * the first chunk as we don't have a transport by then. 903 */ 904 sctp_outq_select_transport(ctx, chunk); 905 906 switch (chunk->chunk_hdr->type) { 907 /* 6.10 Bundling 908 * ... 909 * An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN 910 * COMPLETE with any other chunks. [Send them immediately.] 911 */ 912 case SCTP_CID_INIT: 913 case SCTP_CID_INIT_ACK: 914 case SCTP_CID_SHUTDOWN_COMPLETE: 915 error = sctp_packet_singleton(ctx->transport, chunk, 916 ctx->gfp); 917 if (error < 0) { 918 ctx->asoc->base.sk->sk_err = -error; 919 return; 920 } 921 ctx->asoc->stats.octrlchunks++; 922 break; 923 924 case SCTP_CID_ABORT: 925 if (sctp_test_T_bit(chunk)) 926 ctx->packet->vtag = ctx->asoc->c.my_vtag; 927 fallthrough; 928 929 /* The following chunks are "response" chunks, i.e. 930 * they are generated in response to something we 931 * received. If we are sending these, then we can 932 * send only 1 packet containing these chunks. 933 */ 934 case SCTP_CID_HEARTBEAT_ACK: 935 case SCTP_CID_SHUTDOWN_ACK: 936 case SCTP_CID_COOKIE_ACK: 937 case SCTP_CID_COOKIE_ECHO: 938 case SCTP_CID_ERROR: 939 case SCTP_CID_ECN_CWR: 940 case SCTP_CID_ASCONF_ACK: 941 one_packet = 1; 942 fallthrough; 943 944 case SCTP_CID_HEARTBEAT: 945 if (chunk->pmtu_probe) { 946 error = sctp_packet_singleton(ctx->transport, 947 chunk, ctx->gfp); 948 if (!error) 949 ctx->asoc->stats.octrlchunks++; 950 break; 951 } 952 fallthrough; 953 case SCTP_CID_SACK: 954 case SCTP_CID_SHUTDOWN: 955 case SCTP_CID_ECN_ECNE: 956 case SCTP_CID_ASCONF: 957 case SCTP_CID_FWD_TSN: 958 case SCTP_CID_I_FWD_TSN: 959 case SCTP_CID_RECONF: 960 status = sctp_packet_transmit_chunk(ctx->packet, chunk, 961 one_packet, ctx->gfp); 962 if (status != SCTP_XMIT_OK) { 963 /* put the chunk back */ 964 list_add(&chunk->list, &ctx->q->control_chunk_list); 965 break; 966 } 967 968 ctx->asoc->stats.octrlchunks++; 969 /* PR-SCTP C5) If a FORWARD TSN is sent, the 970 * sender MUST assure that at least one T3-rtx 971 * timer is running. 972 */ 973 if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN || 974 chunk->chunk_hdr->type == SCTP_CID_I_FWD_TSN) { 975 sctp_transport_reset_t3_rtx(ctx->transport); 976 ctx->transport->last_time_sent = jiffies; 977 } 978 979 if (chunk == ctx->asoc->strreset_chunk) 980 sctp_transport_reset_reconf_timer(ctx->transport); 981 982 break; 983 984 default: 985 /* We built a chunk with an illegal type! */ 986 BUG(); 987 } 988 } 989 } 990 991 /* Returns false if new data shouldn't be sent */ 992 static bool sctp_outq_flush_rtx(struct sctp_flush_ctx *ctx, 993 int rtx_timeout) 994 { 995 int error, start_timer = 0; 996 997 if (ctx->asoc->peer.retran_path->state == SCTP_UNCONFIRMED) 998 return false; 999 1000 if (ctx->transport != ctx->asoc->peer.retran_path) { 1001 /* Switch transports & prepare the packet. */ 1002 ctx->transport = ctx->asoc->peer.retran_path; 1003 ctx->packet = &ctx->transport->packet; 1004 1005 if (list_empty(&ctx->transport->send_ready)) 1006 list_add_tail(&ctx->transport->send_ready, 1007 &ctx->transport_list); 1008 1009 sctp_packet_config(ctx->packet, ctx->asoc->peer.i.init_tag, 1010 ctx->asoc->peer.ecn_capable); 1011 } 1012 1013 error = __sctp_outq_flush_rtx(ctx->q, ctx->packet, rtx_timeout, 1014 &start_timer, ctx->gfp); 1015 if (error < 0) 1016 ctx->asoc->base.sk->sk_err = -error; 1017 1018 if (start_timer) { 1019 sctp_transport_reset_t3_rtx(ctx->transport); 1020 ctx->transport->last_time_sent = jiffies; 1021 } 1022 1023 /* This can happen on COOKIE-ECHO resend. Only 1024 * one chunk can get bundled with a COOKIE-ECHO. 1025 */ 1026 if (ctx->packet->has_cookie_echo) 1027 return false; 1028 1029 /* Don't send new data if there is still data 1030 * waiting to retransmit. 1031 */ 1032 if (!list_empty(&ctx->q->retransmit)) 1033 return false; 1034 1035 return true; 1036 } 1037 1038 static void sctp_outq_flush_data(struct sctp_flush_ctx *ctx, 1039 int rtx_timeout) 1040 { 1041 struct sctp_chunk *chunk; 1042 enum sctp_xmit status; 1043 1044 /* Is it OK to send data chunks? */ 1045 switch (ctx->asoc->state) { 1046 case SCTP_STATE_COOKIE_ECHOED: 1047 /* Only allow bundling when this packet has a COOKIE-ECHO 1048 * chunk. 1049 */ 1050 if (!ctx->packet || !ctx->packet->has_cookie_echo) 1051 return; 1052 1053 fallthrough; 1054 case SCTP_STATE_ESTABLISHED: 1055 case SCTP_STATE_SHUTDOWN_PENDING: 1056 case SCTP_STATE_SHUTDOWN_RECEIVED: 1057 break; 1058 1059 default: 1060 /* Do nothing. */ 1061 return; 1062 } 1063 1064 /* RFC 2960 6.1 Transmission of DATA Chunks 1065 * 1066 * C) When the time comes for the sender to transmit, 1067 * before sending new DATA chunks, the sender MUST 1068 * first transmit any outstanding DATA chunks which 1069 * are marked for retransmission (limited by the 1070 * current cwnd). 1071 */ 1072 if (!list_empty(&ctx->q->retransmit) && 1073 !sctp_outq_flush_rtx(ctx, rtx_timeout)) 1074 return; 1075 1076 /* Apply Max.Burst limitation to the current transport in 1077 * case it will be used for new data. We are going to 1078 * rest it before we return, but we want to apply the limit 1079 * to the currently queued data. 1080 */ 1081 if (ctx->transport) 1082 sctp_transport_burst_limited(ctx->transport); 1083 1084 /* Finally, transmit new packets. */ 1085 while ((chunk = sctp_outq_dequeue_data(ctx->q)) != NULL) { 1086 __u32 sid = ntohs(chunk->subh.data_hdr->stream); 1087 __u8 stream_state = SCTP_SO(&ctx->asoc->stream, sid)->state; 1088 1089 /* Has this chunk expired? */ 1090 if (sctp_chunk_abandoned(chunk)) { 1091 sctp_sched_dequeue_done(ctx->q, chunk); 1092 sctp_chunk_fail(chunk, 0); 1093 sctp_chunk_free(chunk); 1094 continue; 1095 } 1096 1097 if (stream_state == SCTP_STREAM_CLOSED) { 1098 sctp_outq_head_data(ctx->q, chunk); 1099 break; 1100 } 1101 1102 sctp_outq_select_transport(ctx, chunk); 1103 1104 pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p skb->users:%d\n", 1105 __func__, ctx->q, chunk, chunk && chunk->chunk_hdr ? 1106 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) : 1107 "illegal chunk", ntohl(chunk->subh.data_hdr->tsn), 1108 chunk->skb ? chunk->skb->head : NULL, chunk->skb ? 1109 refcount_read(&chunk->skb->users) : -1); 1110 1111 /* Add the chunk to the packet. */ 1112 status = sctp_packet_transmit_chunk(ctx->packet, chunk, 0, 1113 ctx->gfp); 1114 if (status != SCTP_XMIT_OK) { 1115 /* We could not append this chunk, so put 1116 * the chunk back on the output queue. 1117 */ 1118 pr_debug("%s: could not transmit tsn:0x%x, status:%d\n", 1119 __func__, ntohl(chunk->subh.data_hdr->tsn), 1120 status); 1121 1122 sctp_outq_head_data(ctx->q, chunk); 1123 break; 1124 } 1125 1126 /* The sender is in the SHUTDOWN-PENDING state, 1127 * The sender MAY set the I-bit in the DATA 1128 * chunk header. 1129 */ 1130 if (ctx->asoc->state == SCTP_STATE_SHUTDOWN_PENDING) 1131 chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM; 1132 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED) 1133 ctx->asoc->stats.ouodchunks++; 1134 else 1135 ctx->asoc->stats.oodchunks++; 1136 1137 /* Only now it's safe to consider this 1138 * chunk as sent, sched-wise. 1139 */ 1140 sctp_sched_dequeue_done(ctx->q, chunk); 1141 1142 list_add_tail(&chunk->transmitted_list, 1143 &ctx->transport->transmitted); 1144 1145 sctp_transport_reset_t3_rtx(ctx->transport); 1146 ctx->transport->last_time_sent = jiffies; 1147 1148 /* Only let one DATA chunk get bundled with a 1149 * COOKIE-ECHO chunk. 1150 */ 1151 if (ctx->packet->has_cookie_echo) 1152 break; 1153 } 1154 } 1155 1156 static void sctp_outq_flush_transports(struct sctp_flush_ctx *ctx) 1157 { 1158 struct sock *sk = ctx->asoc->base.sk; 1159 struct list_head *ltransport; 1160 struct sctp_packet *packet; 1161 struct sctp_transport *t; 1162 int error = 0; 1163 1164 while ((ltransport = sctp_list_dequeue(&ctx->transport_list)) != NULL) { 1165 t = list_entry(ltransport, struct sctp_transport, send_ready); 1166 packet = &t->packet; 1167 if (!sctp_packet_empty(packet)) { 1168 rcu_read_lock(); 1169 if (t->dst && __sk_dst_get(sk) != t->dst) { 1170 dst_hold(t->dst); 1171 sk_setup_caps(sk, t->dst); 1172 } 1173 rcu_read_unlock(); 1174 error = sctp_packet_transmit(packet, ctx->gfp); 1175 if (error < 0) 1176 ctx->q->asoc->base.sk->sk_err = -error; 1177 } 1178 1179 /* Clear the burst limited state, if any */ 1180 sctp_transport_burst_reset(t); 1181 } 1182 } 1183 1184 /* Try to flush an outqueue. 1185 * 1186 * Description: Send everything in q which we legally can, subject to 1187 * congestion limitations. 1188 * * Note: This function can be called from multiple contexts so appropriate 1189 * locking concerns must be made. Today we use the sock lock to protect 1190 * this function. 1191 */ 1192 1193 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp) 1194 { 1195 struct sctp_flush_ctx ctx = { 1196 .q = q, 1197 .transport = NULL, 1198 .transport_list = LIST_HEAD_INIT(ctx.transport_list), 1199 .asoc = q->asoc, 1200 .packet = NULL, 1201 .gfp = gfp, 1202 }; 1203 1204 /* 6.10 Bundling 1205 * ... 1206 * When bundling control chunks with DATA chunks, an 1207 * endpoint MUST place control chunks first in the outbound 1208 * SCTP packet. The transmitter MUST transmit DATA chunks 1209 * within a SCTP packet in increasing order of TSN. 1210 * ... 1211 */ 1212 1213 sctp_outq_flush_ctrl(&ctx); 1214 1215 if (q->asoc->src_out_of_asoc_ok) 1216 goto sctp_flush_out; 1217 1218 sctp_outq_flush_data(&ctx, rtx_timeout); 1219 1220 sctp_flush_out: 1221 1222 sctp_outq_flush_transports(&ctx); 1223 } 1224 1225 /* Update unack_data based on the incoming SACK chunk */ 1226 static void sctp_sack_update_unack_data(struct sctp_association *assoc, 1227 struct sctp_sackhdr *sack) 1228 { 1229 union sctp_sack_variable *frags; 1230 __u16 unack_data; 1231 int i; 1232 1233 unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1; 1234 1235 frags = (union sctp_sack_variable *)(sack + 1); 1236 for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) { 1237 unack_data -= ((ntohs(frags[i].gab.end) - 1238 ntohs(frags[i].gab.start) + 1)); 1239 } 1240 1241 assoc->unack_data = unack_data; 1242 } 1243 1244 /* This is where we REALLY process a SACK. 1245 * 1246 * Process the SACK against the outqueue. Mostly, this just frees 1247 * things off the transmitted queue. 1248 */ 1249 int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk) 1250 { 1251 struct sctp_association *asoc = q->asoc; 1252 struct sctp_sackhdr *sack = chunk->subh.sack_hdr; 1253 struct sctp_transport *transport; 1254 struct sctp_chunk *tchunk = NULL; 1255 struct list_head *lchunk, *transport_list, *temp; 1256 __u32 sack_ctsn, ctsn, tsn; 1257 __u32 highest_tsn, highest_new_tsn; 1258 __u32 sack_a_rwnd; 1259 unsigned int outstanding; 1260 struct sctp_transport *primary = asoc->peer.primary_path; 1261 int count_of_newacks = 0; 1262 int gap_ack_blocks; 1263 u8 accum_moved = 0; 1264 1265 /* Grab the association's destination address list. */ 1266 transport_list = &asoc->peer.transport_addr_list; 1267 1268 /* SCTP path tracepoint for congestion control debugging. */ 1269 if (trace_sctp_probe_path_enabled()) { 1270 list_for_each_entry(transport, transport_list, transports) 1271 trace_sctp_probe_path(transport, asoc); 1272 } 1273 1274 sack_ctsn = ntohl(sack->cum_tsn_ack); 1275 gap_ack_blocks = ntohs(sack->num_gap_ack_blocks); 1276 asoc->stats.gapcnt += gap_ack_blocks; 1277 /* 1278 * SFR-CACC algorithm: 1279 * On receipt of a SACK the sender SHOULD execute the 1280 * following statements. 1281 * 1282 * 1) If the cumulative ack in the SACK passes next tsn_at_change 1283 * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be 1284 * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for 1285 * all destinations. 1286 * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE 1287 * is set the receiver of the SACK MUST take the following actions: 1288 * 1289 * A) Initialize the cacc_saw_newack to 0 for all destination 1290 * addresses. 1291 * 1292 * Only bother if changeover_active is set. Otherwise, this is 1293 * totally suboptimal to do on every SACK. 1294 */ 1295 if (primary->cacc.changeover_active) { 1296 u8 clear_cycling = 0; 1297 1298 if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) { 1299 primary->cacc.changeover_active = 0; 1300 clear_cycling = 1; 1301 } 1302 1303 if (clear_cycling || gap_ack_blocks) { 1304 list_for_each_entry(transport, transport_list, 1305 transports) { 1306 if (clear_cycling) 1307 transport->cacc.cycling_changeover = 0; 1308 if (gap_ack_blocks) 1309 transport->cacc.cacc_saw_newack = 0; 1310 } 1311 } 1312 } 1313 1314 /* Get the highest TSN in the sack. */ 1315 highest_tsn = sack_ctsn; 1316 if (gap_ack_blocks) { 1317 union sctp_sack_variable *frags = 1318 (union sctp_sack_variable *)(sack + 1); 1319 1320 highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end); 1321 } 1322 1323 if (TSN_lt(asoc->highest_sacked, highest_tsn)) 1324 asoc->highest_sacked = highest_tsn; 1325 1326 highest_new_tsn = sack_ctsn; 1327 1328 /* Run through the retransmit queue. Credit bytes received 1329 * and free those chunks that we can. 1330 */ 1331 sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn); 1332 1333 /* Run through the transmitted queue. 1334 * Credit bytes received and free those chunks which we can. 1335 * 1336 * This is a MASSIVE candidate for optimization. 1337 */ 1338 list_for_each_entry(transport, transport_list, transports) { 1339 sctp_check_transmitted(q, &transport->transmitted, 1340 transport, &chunk->source, sack, 1341 &highest_new_tsn); 1342 /* 1343 * SFR-CACC algorithm: 1344 * C) Let count_of_newacks be the number of 1345 * destinations for which cacc_saw_newack is set. 1346 */ 1347 if (transport->cacc.cacc_saw_newack) 1348 count_of_newacks++; 1349 } 1350 1351 /* Move the Cumulative TSN Ack Point if appropriate. */ 1352 if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) { 1353 asoc->ctsn_ack_point = sack_ctsn; 1354 accum_moved = 1; 1355 } 1356 1357 if (gap_ack_blocks) { 1358 1359 if (asoc->fast_recovery && accum_moved) 1360 highest_new_tsn = highest_tsn; 1361 1362 list_for_each_entry(transport, transport_list, transports) 1363 sctp_mark_missing(q, &transport->transmitted, transport, 1364 highest_new_tsn, count_of_newacks); 1365 } 1366 1367 /* Update unack_data field in the assoc. */ 1368 sctp_sack_update_unack_data(asoc, sack); 1369 1370 ctsn = asoc->ctsn_ack_point; 1371 1372 /* Throw away stuff rotting on the sack queue. */ 1373 list_for_each_safe(lchunk, temp, &q->sacked) { 1374 tchunk = list_entry(lchunk, struct sctp_chunk, 1375 transmitted_list); 1376 tsn = ntohl(tchunk->subh.data_hdr->tsn); 1377 if (TSN_lte(tsn, ctsn)) { 1378 list_del_init(&tchunk->transmitted_list); 1379 if (asoc->peer.prsctp_capable && 1380 SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags)) 1381 asoc->sent_cnt_removable--; 1382 sctp_chunk_free(tchunk); 1383 } 1384 } 1385 1386 /* ii) Set rwnd equal to the newly received a_rwnd minus the 1387 * number of bytes still outstanding after processing the 1388 * Cumulative TSN Ack and the Gap Ack Blocks. 1389 */ 1390 1391 sack_a_rwnd = ntohl(sack->a_rwnd); 1392 asoc->peer.zero_window_announced = !sack_a_rwnd; 1393 outstanding = q->outstanding_bytes; 1394 1395 if (outstanding < sack_a_rwnd) 1396 sack_a_rwnd -= outstanding; 1397 else 1398 sack_a_rwnd = 0; 1399 1400 asoc->peer.rwnd = sack_a_rwnd; 1401 1402 asoc->stream.si->generate_ftsn(q, sack_ctsn); 1403 1404 pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn); 1405 pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, " 1406 "advertised peer ack point:0x%x\n", __func__, asoc, ctsn, 1407 asoc->adv_peer_ack_point); 1408 1409 return sctp_outq_is_empty(q); 1410 } 1411 1412 /* Is the outqueue empty? 1413 * The queue is empty when we have not pending data, no in-flight data 1414 * and nothing pending retransmissions. 1415 */ 1416 int sctp_outq_is_empty(const struct sctp_outq *q) 1417 { 1418 return q->out_qlen == 0 && q->outstanding_bytes == 0 && 1419 list_empty(&q->retransmit); 1420 } 1421 1422 /******************************************************************** 1423 * 2nd Level Abstractions 1424 ********************************************************************/ 1425 1426 /* Go through a transport's transmitted list or the association's retransmit 1427 * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked. 1428 * The retransmit list will not have an associated transport. 1429 * 1430 * I added coherent debug information output. --xguo 1431 * 1432 * Instead of printing 'sacked' or 'kept' for each TSN on the 1433 * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5. 1434 * KEPT TSN6-TSN7, etc. 1435 */ 1436 static void sctp_check_transmitted(struct sctp_outq *q, 1437 struct list_head *transmitted_queue, 1438 struct sctp_transport *transport, 1439 union sctp_addr *saddr, 1440 struct sctp_sackhdr *sack, 1441 __u32 *highest_new_tsn_in_sack) 1442 { 1443 struct list_head *lchunk; 1444 struct sctp_chunk *tchunk; 1445 struct list_head tlist; 1446 __u32 tsn; 1447 __u32 sack_ctsn; 1448 __u32 rtt; 1449 __u8 restart_timer = 0; 1450 int bytes_acked = 0; 1451 int migrate_bytes = 0; 1452 bool forward_progress = false; 1453 1454 sack_ctsn = ntohl(sack->cum_tsn_ack); 1455 1456 INIT_LIST_HEAD(&tlist); 1457 1458 /* The while loop will skip empty transmitted queues. */ 1459 while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) { 1460 tchunk = list_entry(lchunk, struct sctp_chunk, 1461 transmitted_list); 1462 1463 if (sctp_chunk_abandoned(tchunk)) { 1464 /* Move the chunk to abandoned list. */ 1465 sctp_insert_list(&q->abandoned, lchunk); 1466 1467 /* If this chunk has not been acked, stop 1468 * considering it as 'outstanding'. 1469 */ 1470 if (transmitted_queue != &q->retransmit && 1471 !tchunk->tsn_gap_acked) { 1472 if (tchunk->transport) 1473 tchunk->transport->flight_size -= 1474 sctp_data_size(tchunk); 1475 q->outstanding_bytes -= sctp_data_size(tchunk); 1476 } 1477 continue; 1478 } 1479 1480 tsn = ntohl(tchunk->subh.data_hdr->tsn); 1481 if (sctp_acked(sack, tsn)) { 1482 /* If this queue is the retransmit queue, the 1483 * retransmit timer has already reclaimed 1484 * the outstanding bytes for this chunk, so only 1485 * count bytes associated with a transport. 1486 */ 1487 if (transport && !tchunk->tsn_gap_acked) { 1488 /* If this chunk is being used for RTT 1489 * measurement, calculate the RTT and update 1490 * the RTO using this value. 1491 * 1492 * 6.3.1 C5) Karn's algorithm: RTT measurements 1493 * MUST NOT be made using packets that were 1494 * retransmitted (and thus for which it is 1495 * ambiguous whether the reply was for the 1496 * first instance of the packet or a later 1497 * instance). 1498 */ 1499 if (!sctp_chunk_retransmitted(tchunk) && 1500 tchunk->rtt_in_progress) { 1501 tchunk->rtt_in_progress = 0; 1502 rtt = jiffies - tchunk->sent_at; 1503 sctp_transport_update_rto(transport, 1504 rtt); 1505 } 1506 1507 if (TSN_lte(tsn, sack_ctsn)) { 1508 /* 1509 * SFR-CACC algorithm: 1510 * 2) If the SACK contains gap acks 1511 * and the flag CHANGEOVER_ACTIVE is 1512 * set the receiver of the SACK MUST 1513 * take the following action: 1514 * 1515 * B) For each TSN t being acked that 1516 * has not been acked in any SACK so 1517 * far, set cacc_saw_newack to 1 for 1518 * the destination that the TSN was 1519 * sent to. 1520 */ 1521 if (sack->num_gap_ack_blocks && 1522 q->asoc->peer.primary_path->cacc. 1523 changeover_active) 1524 transport->cacc.cacc_saw_newack 1525 = 1; 1526 } 1527 } 1528 1529 /* If the chunk hasn't been marked as ACKED, 1530 * mark it and account bytes_acked if the 1531 * chunk had a valid transport (it will not 1532 * have a transport if ASCONF had deleted it 1533 * while DATA was outstanding). 1534 */ 1535 if (!tchunk->tsn_gap_acked) { 1536 tchunk->tsn_gap_acked = 1; 1537 if (TSN_lt(*highest_new_tsn_in_sack, tsn)) 1538 *highest_new_tsn_in_sack = tsn; 1539 bytes_acked += sctp_data_size(tchunk); 1540 if (!tchunk->transport) 1541 migrate_bytes += sctp_data_size(tchunk); 1542 forward_progress = true; 1543 } 1544 1545 if (TSN_lte(tsn, sack_ctsn)) { 1546 /* RFC 2960 6.3.2 Retransmission Timer Rules 1547 * 1548 * R3) Whenever a SACK is received 1549 * that acknowledges the DATA chunk 1550 * with the earliest outstanding TSN 1551 * for that address, restart T3-rtx 1552 * timer for that address with its 1553 * current RTO. 1554 */ 1555 restart_timer = 1; 1556 forward_progress = true; 1557 1558 list_add_tail(&tchunk->transmitted_list, 1559 &q->sacked); 1560 } else { 1561 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2 1562 * M2) Each time a SACK arrives reporting 1563 * 'Stray DATA chunk(s)' record the highest TSN 1564 * reported as newly acknowledged, call this 1565 * value 'HighestTSNinSack'. A newly 1566 * acknowledged DATA chunk is one not 1567 * previously acknowledged in a SACK. 1568 * 1569 * When the SCTP sender of data receives a SACK 1570 * chunk that acknowledges, for the first time, 1571 * the receipt of a DATA chunk, all the still 1572 * unacknowledged DATA chunks whose TSN is 1573 * older than that newly acknowledged DATA 1574 * chunk, are qualified as 'Stray DATA chunks'. 1575 */ 1576 list_add_tail(lchunk, &tlist); 1577 } 1578 } else { 1579 if (tchunk->tsn_gap_acked) { 1580 pr_debug("%s: receiver reneged on data TSN:0x%x\n", 1581 __func__, tsn); 1582 1583 tchunk->tsn_gap_acked = 0; 1584 1585 if (tchunk->transport) 1586 bytes_acked -= sctp_data_size(tchunk); 1587 1588 /* RFC 2960 6.3.2 Retransmission Timer Rules 1589 * 1590 * R4) Whenever a SACK is received missing a 1591 * TSN that was previously acknowledged via a 1592 * Gap Ack Block, start T3-rtx for the 1593 * destination address to which the DATA 1594 * chunk was originally 1595 * transmitted if it is not already running. 1596 */ 1597 restart_timer = 1; 1598 } 1599 1600 list_add_tail(lchunk, &tlist); 1601 } 1602 } 1603 1604 if (transport) { 1605 if (bytes_acked) { 1606 struct sctp_association *asoc = transport->asoc; 1607 1608 /* We may have counted DATA that was migrated 1609 * to this transport due to DEL-IP operation. 1610 * Subtract those bytes, since the were never 1611 * send on this transport and shouldn't be 1612 * credited to this transport. 1613 */ 1614 bytes_acked -= migrate_bytes; 1615 1616 /* 8.2. When an outstanding TSN is acknowledged, 1617 * the endpoint shall clear the error counter of 1618 * the destination transport address to which the 1619 * DATA chunk was last sent. 1620 * The association's overall error counter is 1621 * also cleared. 1622 */ 1623 transport->error_count = 0; 1624 transport->asoc->overall_error_count = 0; 1625 forward_progress = true; 1626 1627 /* 1628 * While in SHUTDOWN PENDING, we may have started 1629 * the T5 shutdown guard timer after reaching the 1630 * retransmission limit. Stop that timer as soon 1631 * as the receiver acknowledged any data. 1632 */ 1633 if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING && 1634 timer_delete(&asoc->timers[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD])) 1635 sctp_association_put(asoc); 1636 1637 /* Mark the destination transport address as 1638 * active if it is not so marked. 1639 */ 1640 if ((transport->state == SCTP_INACTIVE || 1641 transport->state == SCTP_UNCONFIRMED) && 1642 sctp_cmp_addr_exact(&transport->ipaddr, saddr)) { 1643 sctp_assoc_control_transport( 1644 transport->asoc, 1645 transport, 1646 SCTP_TRANSPORT_UP, 1647 SCTP_RECEIVED_SACK); 1648 } 1649 1650 sctp_transport_raise_cwnd(transport, sack_ctsn, 1651 bytes_acked); 1652 1653 transport->flight_size -= bytes_acked; 1654 if (transport->flight_size == 0) 1655 transport->partial_bytes_acked = 0; 1656 q->outstanding_bytes -= bytes_acked + migrate_bytes; 1657 } else { 1658 /* RFC 2960 6.1, sctpimpguide-06 2.15.2 1659 * When a sender is doing zero window probing, it 1660 * should not timeout the association if it continues 1661 * to receive new packets from the receiver. The 1662 * reason is that the receiver MAY keep its window 1663 * closed for an indefinite time. 1664 * A sender is doing zero window probing when the 1665 * receiver's advertised window is zero, and there is 1666 * only one data chunk in flight to the receiver. 1667 * 1668 * Allow the association to timeout while in SHUTDOWN 1669 * PENDING or SHUTDOWN RECEIVED in case the receiver 1670 * stays in zero window mode forever. 1671 */ 1672 if (!q->asoc->peer.rwnd && 1673 !list_empty(&tlist) && 1674 (sack_ctsn+2 == q->asoc->next_tsn) && 1675 q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) { 1676 pr_debug("%s: sack received for zero window " 1677 "probe:%u\n", __func__, sack_ctsn); 1678 1679 q->asoc->overall_error_count = 0; 1680 transport->error_count = 0; 1681 } 1682 } 1683 1684 /* RFC 2960 6.3.2 Retransmission Timer Rules 1685 * 1686 * R2) Whenever all outstanding data sent to an address have 1687 * been acknowledged, turn off the T3-rtx timer of that 1688 * address. 1689 */ 1690 if (!transport->flight_size) { 1691 if (timer_delete(&transport->T3_rtx_timer)) 1692 sctp_transport_put(transport); 1693 } else if (restart_timer) { 1694 if (!mod_timer(&transport->T3_rtx_timer, 1695 jiffies + transport->rto)) 1696 sctp_transport_hold(transport); 1697 } 1698 1699 if (forward_progress) { 1700 if (transport->dst) 1701 sctp_transport_dst_confirm(transport); 1702 } 1703 } 1704 1705 list_splice(&tlist, transmitted_queue); 1706 } 1707 1708 /* Mark chunks as missing and consequently may get retransmitted. */ 1709 static void sctp_mark_missing(struct sctp_outq *q, 1710 struct list_head *transmitted_queue, 1711 struct sctp_transport *transport, 1712 __u32 highest_new_tsn_in_sack, 1713 int count_of_newacks) 1714 { 1715 struct sctp_chunk *chunk; 1716 __u32 tsn; 1717 char do_fast_retransmit = 0; 1718 struct sctp_association *asoc = q->asoc; 1719 struct sctp_transport *primary = asoc->peer.primary_path; 1720 1721 list_for_each_entry(chunk, transmitted_queue, transmitted_list) { 1722 1723 tsn = ntohl(chunk->subh.data_hdr->tsn); 1724 1725 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all 1726 * 'Unacknowledged TSN's', if the TSN number of an 1727 * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack' 1728 * value, increment the 'TSN.Missing.Report' count on that 1729 * chunk if it has NOT been fast retransmitted or marked for 1730 * fast retransmit already. 1731 */ 1732 if (chunk->fast_retransmit == SCTP_CAN_FRTX && 1733 !chunk->tsn_gap_acked && 1734 TSN_lt(tsn, highest_new_tsn_in_sack)) { 1735 1736 /* SFR-CACC may require us to skip marking 1737 * this chunk as missing. 1738 */ 1739 if (!transport || !sctp_cacc_skip(primary, 1740 chunk->transport, 1741 count_of_newacks, tsn)) { 1742 chunk->tsn_missing_report++; 1743 1744 pr_debug("%s: tsn:0x%x missing counter:%d\n", 1745 __func__, tsn, chunk->tsn_missing_report); 1746 } 1747 } 1748 /* 1749 * M4) If any DATA chunk is found to have a 1750 * 'TSN.Missing.Report' 1751 * value larger than or equal to 3, mark that chunk for 1752 * retransmission and start the fast retransmit procedure. 1753 */ 1754 1755 if (chunk->tsn_missing_report >= 3) { 1756 chunk->fast_retransmit = SCTP_NEED_FRTX; 1757 do_fast_retransmit = 1; 1758 } 1759 } 1760 1761 if (transport) { 1762 if (do_fast_retransmit) 1763 sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX); 1764 1765 pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, " 1766 "flight_size:%d, pba:%d\n", __func__, transport, 1767 transport->cwnd, transport->ssthresh, 1768 transport->flight_size, transport->partial_bytes_acked); 1769 } 1770 } 1771 1772 /* Is the given TSN acked by this packet? */ 1773 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn) 1774 { 1775 __u32 ctsn = ntohl(sack->cum_tsn_ack); 1776 union sctp_sack_variable *frags; 1777 __u16 tsn_offset, blocks; 1778 int i; 1779 1780 if (TSN_lte(tsn, ctsn)) 1781 goto pass; 1782 1783 /* 3.3.4 Selective Acknowledgment (SACK) (3): 1784 * 1785 * Gap Ack Blocks: 1786 * These fields contain the Gap Ack Blocks. They are repeated 1787 * for each Gap Ack Block up to the number of Gap Ack Blocks 1788 * defined in the Number of Gap Ack Blocks field. All DATA 1789 * chunks with TSNs greater than or equal to (Cumulative TSN 1790 * Ack + Gap Ack Block Start) and less than or equal to 1791 * (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack 1792 * Block are assumed to have been received correctly. 1793 */ 1794 1795 frags = (union sctp_sack_variable *)(sack + 1); 1796 blocks = ntohs(sack->num_gap_ack_blocks); 1797 tsn_offset = tsn - ctsn; 1798 for (i = 0; i < blocks; ++i) { 1799 if (tsn_offset >= ntohs(frags[i].gab.start) && 1800 tsn_offset <= ntohs(frags[i].gab.end)) 1801 goto pass; 1802 } 1803 1804 return 0; 1805 pass: 1806 return 1; 1807 } 1808 1809 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist, 1810 int nskips, __be16 stream) 1811 { 1812 int i; 1813 1814 for (i = 0; i < nskips; i++) { 1815 if (skiplist[i].stream == stream) 1816 return i; 1817 } 1818 return i; 1819 } 1820 1821 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */ 1822 void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn) 1823 { 1824 struct sctp_association *asoc = q->asoc; 1825 struct sctp_chunk *ftsn_chunk = NULL; 1826 struct sctp_fwdtsn_skip ftsn_skip_arr[10]; 1827 int nskips = 0; 1828 int skip_pos = 0; 1829 __u32 tsn; 1830 struct sctp_chunk *chunk; 1831 struct list_head *lchunk, *temp; 1832 1833 if (!asoc->peer.prsctp_capable) 1834 return; 1835 1836 /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the 1837 * received SACK. 1838 * 1839 * If (Advanced.Peer.Ack.Point < SackCumAck), then update 1840 * Advanced.Peer.Ack.Point to be equal to SackCumAck. 1841 */ 1842 if (TSN_lt(asoc->adv_peer_ack_point, ctsn)) 1843 asoc->adv_peer_ack_point = ctsn; 1844 1845 /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point" 1846 * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as 1847 * the chunk next in the out-queue space is marked as "abandoned" as 1848 * shown in the following example: 1849 * 1850 * Assuming that a SACK arrived with the Cumulative TSN ACK 102 1851 * and the Advanced.Peer.Ack.Point is updated to this value: 1852 * 1853 * out-queue at the end of ==> out-queue after Adv.Ack.Point 1854 * normal SACK processing local advancement 1855 * ... ... 1856 * Adv.Ack.Pt-> 102 acked 102 acked 1857 * 103 abandoned 103 abandoned 1858 * 104 abandoned Adv.Ack.P-> 104 abandoned 1859 * 105 105 1860 * 106 acked 106 acked 1861 * ... ... 1862 * 1863 * In this example, the data sender successfully advanced the 1864 * "Advanced.Peer.Ack.Point" from 102 to 104 locally. 1865 */ 1866 list_for_each_safe(lchunk, temp, &q->abandoned) { 1867 chunk = list_entry(lchunk, struct sctp_chunk, 1868 transmitted_list); 1869 tsn = ntohl(chunk->subh.data_hdr->tsn); 1870 1871 /* Remove any chunks in the abandoned queue that are acked by 1872 * the ctsn. 1873 */ 1874 if (TSN_lte(tsn, ctsn)) { 1875 list_del_init(lchunk); 1876 sctp_chunk_free(chunk); 1877 } else { 1878 if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) { 1879 asoc->adv_peer_ack_point = tsn; 1880 if (chunk->chunk_hdr->flags & 1881 SCTP_DATA_UNORDERED) 1882 continue; 1883 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0], 1884 nskips, 1885 chunk->subh.data_hdr->stream); 1886 ftsn_skip_arr[skip_pos].stream = 1887 chunk->subh.data_hdr->stream; 1888 ftsn_skip_arr[skip_pos].ssn = 1889 chunk->subh.data_hdr->ssn; 1890 if (skip_pos == nskips) 1891 nskips++; 1892 if (nskips == 10) 1893 break; 1894 } else 1895 break; 1896 } 1897 } 1898 1899 /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point" 1900 * is greater than the Cumulative TSN ACK carried in the received 1901 * SACK, the data sender MUST send the data receiver a FORWARD TSN 1902 * chunk containing the latest value of the 1903 * "Advanced.Peer.Ack.Point". 1904 * 1905 * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD 1906 * list each stream and sequence number in the forwarded TSN. This 1907 * information will enable the receiver to easily find any 1908 * stranded TSN's waiting on stream reorder queues. Each stream 1909 * SHOULD only be reported once; this means that if multiple 1910 * abandoned messages occur in the same stream then only the 1911 * highest abandoned stream sequence number is reported. If the 1912 * total size of the FORWARD TSN does NOT fit in a single MTU then 1913 * the sender of the FORWARD TSN SHOULD lower the 1914 * Advanced.Peer.Ack.Point to the last TSN that will fit in a 1915 * single MTU. 1916 */ 1917 if (asoc->adv_peer_ack_point > ctsn) 1918 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point, 1919 nskips, &ftsn_skip_arr[0]); 1920 1921 if (ftsn_chunk) { 1922 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list); 1923 SCTP_INC_STATS(asoc->base.net, SCTP_MIB_OUTCTRLCHUNKS); 1924 } 1925 } 1926