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. */
sctp_outq_head_data(struct sctp_outq * q,struct sctp_chunk * ch)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. */
sctp_outq_dequeue_data(struct sctp_outq * q)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. */
sctp_outq_tail_data(struct sctp_outq * q,struct sctp_chunk * ch)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 */
sctp_cacc_skip_3_1_d(struct sctp_transport * primary,struct sctp_transport * transport,int count_of_newacks)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 */
sctp_cacc_skip_3_1_f(struct sctp_transport * transport,int count_of_newacks)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 */
sctp_cacc_skip_3_1(struct sctp_transport * primary,struct sctp_transport * transport,int count_of_newacks)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 */
sctp_cacc_skip_3_2(struct sctp_transport * primary,__u32 tsn)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 */
sctp_cacc_skip(struct sctp_transport * primary,struct sctp_transport * transport,int count_of_newacks,__u32 tsn)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 */
sctp_outq_init(struct sctp_association * asoc,struct sctp_outq * q)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 */
__sctp_outq_teardown(struct sctp_outq * q)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
sctp_outq_teardown(struct sctp_outq * q)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. */
sctp_outq_free(struct sctp_outq * q)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. */
sctp_outq_tail(struct sctp_outq * q,struct sctp_chunk * chunk,gfp_t gfp)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 */
sctp_insert_list(struct list_head * head,struct list_head * new)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
sctp_prsctp_prune_sent(struct sctp_association * asoc,struct sctp_sndrcvinfo * sinfo,struct list_head * queue,int msg_len)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
sctp_prsctp_prune_unsent(struct sctp_association * asoc,struct sctp_sndrcvinfo * sinfo,int msg_len)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 */
sctp_prsctp_prune(struct sctp_association * asoc,struct sctp_sndrcvinfo * sinfo,int msg_len)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. */
sctp_retransmit_mark(struct sctp_outq * q,struct sctp_transport * transport,__u8 reason)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 */
sctp_retransmit(struct sctp_outq * q,struct sctp_transport * transport,enum sctp_retransmit_reason reason)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 break;
554 case SCTP_RTXR_FAST_RTX:
555 SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
556 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
557 q->fast_rtx = 1;
558 break;
559 case SCTP_RTXR_PMTUD:
560 SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
561 break;
562 case SCTP_RTXR_T1_RTX:
563 SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
564 transport->asoc->init_retries++;
565 break;
566 default:
567 BUG();
568 }
569
570 sctp_retransmit_mark(q, transport, reason);
571
572 /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
573 * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
574 * following the procedures outlined in C1 - C5.
575 */
576 if (reason == SCTP_RTXR_T3_RTX)
577 q->asoc->stream.si->generate_ftsn(q, q->asoc->ctsn_ack_point);
578
579 /* Flush the queues only on timeout, since fast_rtx is only
580 * triggered during sack processing and the queue
581 * will be flushed at the end.
582 */
583 if (reason != SCTP_RTXR_FAST_RTX)
584 sctp_outq_flush(q, /* rtx_timeout */ 1, GFP_ATOMIC);
585 }
586
587 /*
588 * Transmit DATA chunks on the retransmit queue. Upon return from
589 * __sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
590 * need to be transmitted by the caller.
591 * We assume that pkt->transport has already been set.
592 *
593 * The return value is a normal kernel error return value.
594 */
__sctp_outq_flush_rtx(struct sctp_outq * q,struct sctp_packet * pkt,int rtx_timeout,int * start_timer,gfp_t gfp)595 static int __sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
596 int rtx_timeout, int *start_timer, gfp_t gfp)
597 {
598 struct sctp_transport *transport = pkt->transport;
599 struct sctp_chunk *chunk, *chunk1;
600 struct list_head *lqueue;
601 enum sctp_xmit status;
602 int error = 0;
603 int timer = 0;
604 int done = 0;
605 int fast_rtx;
606
607 lqueue = &q->retransmit;
608 fast_rtx = q->fast_rtx;
609
610 /* This loop handles time-out retransmissions, fast retransmissions,
611 * and retransmissions due to opening of whindow.
612 *
613 * RFC 2960 6.3.3 Handle T3-rtx Expiration
614 *
615 * E3) Determine how many of the earliest (i.e., lowest TSN)
616 * outstanding DATA chunks for the address for which the
617 * T3-rtx has expired will fit into a single packet, subject
618 * to the MTU constraint for the path corresponding to the
619 * destination transport address to which the retransmission
620 * is being sent (this may be different from the address for
621 * which the timer expires [see Section 6.4]). Call this value
622 * K. Bundle and retransmit those K DATA chunks in a single
623 * packet to the destination endpoint.
624 *
625 * [Just to be painfully clear, if we are retransmitting
626 * because a timeout just happened, we should send only ONE
627 * packet of retransmitted data.]
628 *
629 * For fast retransmissions we also send only ONE packet. However,
630 * if we are just flushing the queue due to open window, we'll
631 * try to send as much as possible.
632 */
633 list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
634 /* If the chunk is abandoned, move it to abandoned list. */
635 if (sctp_chunk_abandoned(chunk)) {
636 list_del_init(&chunk->transmitted_list);
637 sctp_insert_list(&q->abandoned,
638 &chunk->transmitted_list);
639 continue;
640 }
641
642 /* Make sure that Gap Acked TSNs are not retransmitted. A
643 * simple approach is just to move such TSNs out of the
644 * way and into a 'transmitted' queue and skip to the
645 * next chunk.
646 */
647 if (chunk->tsn_gap_acked) {
648 list_move_tail(&chunk->transmitted_list,
649 &transport->transmitted);
650 continue;
651 }
652
653 /* If we are doing fast retransmit, ignore non-fast_rtransmit
654 * chunks
655 */
656 if (fast_rtx && !chunk->fast_retransmit)
657 continue;
658
659 redo:
660 /* Attempt to append this chunk to the packet. */
661 status = sctp_packet_append_chunk(pkt, chunk);
662
663 switch (status) {
664 case SCTP_XMIT_PMTU_FULL:
665 if (!pkt->has_data && !pkt->has_cookie_echo) {
666 /* If this packet did not contain DATA then
667 * retransmission did not happen, so do it
668 * again. We'll ignore the error here since
669 * control chunks are already freed so there
670 * is nothing we can do.
671 */
672 sctp_packet_transmit(pkt, gfp);
673 goto redo;
674 }
675
676 /* Send this packet. */
677 error = sctp_packet_transmit(pkt, gfp);
678
679 /* If we are retransmitting, we should only
680 * send a single packet.
681 * Otherwise, try appending this chunk again.
682 */
683 if (rtx_timeout || fast_rtx)
684 done = 1;
685 else
686 goto redo;
687
688 /* Bundle next chunk in the next round. */
689 break;
690
691 case SCTP_XMIT_RWND_FULL:
692 /* Send this packet. */
693 error = sctp_packet_transmit(pkt, gfp);
694
695 /* Stop sending DATA as there is no more room
696 * at the receiver.
697 */
698 done = 1;
699 break;
700
701 case SCTP_XMIT_DELAY:
702 /* Send this packet. */
703 error = sctp_packet_transmit(pkt, gfp);
704
705 /* Stop sending DATA because of nagle delay. */
706 done = 1;
707 break;
708
709 default:
710 /* The append was successful, so add this chunk to
711 * the transmitted list.
712 */
713 list_move_tail(&chunk->transmitted_list,
714 &transport->transmitted);
715
716 /* Mark the chunk as ineligible for fast retransmit
717 * after it is retransmitted.
718 */
719 if (chunk->fast_retransmit == SCTP_NEED_FRTX)
720 chunk->fast_retransmit = SCTP_DONT_FRTX;
721
722 q->asoc->stats.rtxchunks++;
723 break;
724 }
725
726 /* Set the timer if there were no errors */
727 if (!error && !timer)
728 timer = 1;
729
730 if (done)
731 break;
732 }
733
734 /* If we are here due to a retransmit timeout or a fast
735 * retransmit and if there are any chunks left in the retransmit
736 * queue that could not fit in the PMTU sized packet, they need
737 * to be marked as ineligible for a subsequent fast retransmit.
738 */
739 if (rtx_timeout || fast_rtx) {
740 list_for_each_entry(chunk1, lqueue, transmitted_list) {
741 if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
742 chunk1->fast_retransmit = SCTP_DONT_FRTX;
743 }
744 }
745
746 *start_timer = timer;
747
748 /* Clear fast retransmit hint */
749 if (fast_rtx)
750 q->fast_rtx = 0;
751
752 return error;
753 }
754
755 /* Cork the outqueue so queued chunks are really queued. */
sctp_outq_uncork(struct sctp_outq * q,gfp_t gfp)756 void sctp_outq_uncork(struct sctp_outq *q, gfp_t gfp)
757 {
758 if (q->cork)
759 q->cork = 0;
760
761 sctp_outq_flush(q, 0, gfp);
762 }
763
sctp_packet_singleton(struct sctp_transport * transport,struct sctp_chunk * chunk,gfp_t gfp)764 static int sctp_packet_singleton(struct sctp_transport *transport,
765 struct sctp_chunk *chunk, gfp_t gfp)
766 {
767 const struct sctp_association *asoc = transport->asoc;
768 const __u16 sport = asoc->base.bind_addr.port;
769 const __u16 dport = asoc->peer.port;
770 const __u32 vtag = asoc->peer.i.init_tag;
771 struct sctp_packet singleton;
772
773 sctp_packet_init(&singleton, transport, sport, dport);
774 sctp_packet_config(&singleton, vtag, 0);
775 if (sctp_packet_append_chunk(&singleton, chunk) != SCTP_XMIT_OK) {
776 list_del_init(&chunk->list);
777 sctp_chunk_free(chunk);
778 return -ENOMEM;
779 }
780 return sctp_packet_transmit(&singleton, gfp);
781 }
782
783 /* Struct to hold the context during sctp outq flush */
784 struct sctp_flush_ctx {
785 struct sctp_outq *q;
786 /* Current transport being used. It's NOT the same as curr active one */
787 struct sctp_transport *transport;
788 /* These transports have chunks to send. */
789 struct list_head transport_list;
790 struct sctp_association *asoc;
791 /* Packet on the current transport above */
792 struct sctp_packet *packet;
793 gfp_t gfp;
794 };
795
796 /* transport: current transport */
sctp_outq_select_transport(struct sctp_flush_ctx * ctx,struct sctp_chunk * chunk)797 static void sctp_outq_select_transport(struct sctp_flush_ctx *ctx,
798 struct sctp_chunk *chunk)
799 {
800 struct sctp_transport *new_transport = chunk->transport;
801
802 if (!new_transport) {
803 if (!sctp_chunk_is_data(chunk)) {
804 /* If we have a prior transport pointer, see if
805 * the destination address of the chunk
806 * matches the destination address of the
807 * current transport. If not a match, then
808 * try to look up the transport with a given
809 * destination address. We do this because
810 * after processing ASCONFs, we may have new
811 * transports created.
812 */
813 if (ctx->transport && sctp_cmp_addr_exact(&chunk->dest,
814 &ctx->transport->ipaddr))
815 new_transport = ctx->transport;
816 else
817 new_transport = sctp_assoc_lookup_paddr(ctx->asoc,
818 &chunk->dest);
819 }
820
821 /* if we still don't have a new transport, then
822 * use the current active path.
823 */
824 if (!new_transport)
825 new_transport = ctx->asoc->peer.active_path;
826 } else {
827 __u8 type;
828
829 switch (new_transport->state) {
830 case SCTP_INACTIVE:
831 case SCTP_UNCONFIRMED:
832 case SCTP_PF:
833 /* If the chunk is Heartbeat or Heartbeat Ack,
834 * send it to chunk->transport, even if it's
835 * inactive.
836 *
837 * 3.3.6 Heartbeat Acknowledgement:
838 * ...
839 * A HEARTBEAT ACK is always sent to the source IP
840 * address of the IP datagram containing the
841 * HEARTBEAT chunk to which this ack is responding.
842 * ...
843 *
844 * ASCONF_ACKs also must be sent to the source.
845 */
846 type = chunk->chunk_hdr->type;
847 if (type != SCTP_CID_HEARTBEAT &&
848 type != SCTP_CID_HEARTBEAT_ACK &&
849 type != SCTP_CID_ASCONF_ACK)
850 new_transport = ctx->asoc->peer.active_path;
851 break;
852 default:
853 break;
854 }
855 }
856
857 /* Are we switching transports? Take care of transport locks. */
858 if (new_transport != ctx->transport) {
859 ctx->transport = new_transport;
860 ctx->packet = &ctx->transport->packet;
861
862 if (list_empty(&ctx->transport->send_ready))
863 list_add_tail(&ctx->transport->send_ready,
864 &ctx->transport_list);
865
866 sctp_packet_config(ctx->packet,
867 ctx->asoc->peer.i.init_tag,
868 ctx->asoc->peer.ecn_capable);
869 /* We've switched transports, so apply the
870 * Burst limit to the new transport.
871 */
872 sctp_transport_burst_limited(ctx->transport);
873 }
874 }
875
sctp_outq_flush_ctrl(struct sctp_flush_ctx * ctx)876 static void sctp_outq_flush_ctrl(struct sctp_flush_ctx *ctx)
877 {
878 struct sctp_chunk *chunk, *tmp;
879 enum sctp_xmit status;
880 int one_packet, error;
881
882 list_for_each_entry_safe(chunk, tmp, &ctx->q->control_chunk_list, list) {
883 one_packet = 0;
884
885 /* RFC 5061, 5.3
886 * F1) This means that until such time as the ASCONF
887 * containing the add is acknowledged, the sender MUST
888 * NOT use the new IP address as a source for ANY SCTP
889 * packet except on carrying an ASCONF Chunk.
890 */
891 if (ctx->asoc->src_out_of_asoc_ok &&
892 chunk->chunk_hdr->type != SCTP_CID_ASCONF)
893 continue;
894
895 list_del_init(&chunk->list);
896
897 /* Pick the right transport to use. Should always be true for
898 * the first chunk as we don't have a transport by then.
899 */
900 sctp_outq_select_transport(ctx, chunk);
901
902 switch (chunk->chunk_hdr->type) {
903 /* 6.10 Bundling
904 * ...
905 * An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
906 * COMPLETE with any other chunks. [Send them immediately.]
907 */
908 case SCTP_CID_INIT:
909 case SCTP_CID_INIT_ACK:
910 case SCTP_CID_SHUTDOWN_COMPLETE:
911 error = sctp_packet_singleton(ctx->transport, chunk,
912 ctx->gfp);
913 if (error < 0) {
914 ctx->asoc->base.sk->sk_err = -error;
915 return;
916 }
917 ctx->asoc->stats.octrlchunks++;
918 break;
919
920 case SCTP_CID_ABORT:
921 if (sctp_test_T_bit(chunk))
922 ctx->packet->vtag = ctx->asoc->c.my_vtag;
923 fallthrough;
924
925 /* The following chunks are "response" chunks, i.e.
926 * they are generated in response to something we
927 * received. If we are sending these, then we can
928 * send only 1 packet containing these chunks.
929 */
930 case SCTP_CID_HEARTBEAT_ACK:
931 case SCTP_CID_SHUTDOWN_ACK:
932 case SCTP_CID_COOKIE_ACK:
933 case SCTP_CID_COOKIE_ECHO:
934 case SCTP_CID_ERROR:
935 case SCTP_CID_ECN_CWR:
936 case SCTP_CID_ASCONF_ACK:
937 one_packet = 1;
938 fallthrough;
939
940 case SCTP_CID_HEARTBEAT:
941 if (chunk->pmtu_probe) {
942 error = sctp_packet_singleton(ctx->transport,
943 chunk, ctx->gfp);
944 if (!error)
945 ctx->asoc->stats.octrlchunks++;
946 break;
947 }
948 fallthrough;
949 case SCTP_CID_SACK:
950 case SCTP_CID_SHUTDOWN:
951 case SCTP_CID_ECN_ECNE:
952 case SCTP_CID_ASCONF:
953 case SCTP_CID_FWD_TSN:
954 case SCTP_CID_I_FWD_TSN:
955 case SCTP_CID_RECONF:
956 status = sctp_packet_transmit_chunk(ctx->packet, chunk,
957 one_packet, ctx->gfp);
958 if (status != SCTP_XMIT_OK) {
959 /* put the chunk back */
960 list_add(&chunk->list, &ctx->q->control_chunk_list);
961 break;
962 }
963
964 ctx->asoc->stats.octrlchunks++;
965 /* PR-SCTP C5) If a FORWARD TSN is sent, the
966 * sender MUST assure that at least one T3-rtx
967 * timer is running.
968 */
969 if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN ||
970 chunk->chunk_hdr->type == SCTP_CID_I_FWD_TSN) {
971 sctp_transport_reset_t3_rtx(ctx->transport);
972 ctx->transport->last_time_sent = jiffies;
973 }
974
975 if (chunk == ctx->asoc->strreset_chunk)
976 sctp_transport_reset_reconf_timer(ctx->transport);
977
978 break;
979
980 default:
981 /* We built a chunk with an illegal type! */
982 BUG();
983 }
984 }
985 }
986
987 /* Returns false if new data shouldn't be sent */
sctp_outq_flush_rtx(struct sctp_flush_ctx * ctx,int rtx_timeout)988 static bool sctp_outq_flush_rtx(struct sctp_flush_ctx *ctx,
989 int rtx_timeout)
990 {
991 int error, start_timer = 0;
992
993 if (ctx->asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
994 return false;
995
996 if (ctx->transport != ctx->asoc->peer.retran_path) {
997 /* Switch transports & prepare the packet. */
998 ctx->transport = ctx->asoc->peer.retran_path;
999 ctx->packet = &ctx->transport->packet;
1000
1001 if (list_empty(&ctx->transport->send_ready))
1002 list_add_tail(&ctx->transport->send_ready,
1003 &ctx->transport_list);
1004
1005 sctp_packet_config(ctx->packet, ctx->asoc->peer.i.init_tag,
1006 ctx->asoc->peer.ecn_capable);
1007 }
1008
1009 error = __sctp_outq_flush_rtx(ctx->q, ctx->packet, rtx_timeout,
1010 &start_timer, ctx->gfp);
1011 if (error < 0)
1012 ctx->asoc->base.sk->sk_err = -error;
1013
1014 if (start_timer) {
1015 sctp_transport_reset_t3_rtx(ctx->transport);
1016 ctx->transport->last_time_sent = jiffies;
1017 }
1018
1019 /* This can happen on COOKIE-ECHO resend. Only
1020 * one chunk can get bundled with a COOKIE-ECHO.
1021 */
1022 if (ctx->packet->has_cookie_echo)
1023 return false;
1024
1025 /* Don't send new data if there is still data
1026 * waiting to retransmit.
1027 */
1028 if (!list_empty(&ctx->q->retransmit))
1029 return false;
1030
1031 return true;
1032 }
1033
sctp_outq_flush_data(struct sctp_flush_ctx * ctx,int rtx_timeout)1034 static void sctp_outq_flush_data(struct sctp_flush_ctx *ctx,
1035 int rtx_timeout)
1036 {
1037 struct sctp_chunk *chunk;
1038 enum sctp_xmit status;
1039
1040 /* Is it OK to send data chunks? */
1041 switch (ctx->asoc->state) {
1042 case SCTP_STATE_COOKIE_ECHOED:
1043 /* Only allow bundling when this packet has a COOKIE-ECHO
1044 * chunk.
1045 */
1046 if (!ctx->packet || !ctx->packet->has_cookie_echo)
1047 return;
1048
1049 fallthrough;
1050 case SCTP_STATE_ESTABLISHED:
1051 case SCTP_STATE_SHUTDOWN_PENDING:
1052 case SCTP_STATE_SHUTDOWN_RECEIVED:
1053 break;
1054
1055 default:
1056 /* Do nothing. */
1057 return;
1058 }
1059
1060 /* RFC 2960 6.1 Transmission of DATA Chunks
1061 *
1062 * C) When the time comes for the sender to transmit,
1063 * before sending new DATA chunks, the sender MUST
1064 * first transmit any outstanding DATA chunks which
1065 * are marked for retransmission (limited by the
1066 * current cwnd).
1067 */
1068 if (!list_empty(&ctx->q->retransmit) &&
1069 !sctp_outq_flush_rtx(ctx, rtx_timeout))
1070 return;
1071
1072 /* Apply Max.Burst limitation to the current transport in
1073 * case it will be used for new data. We are going to
1074 * rest it before we return, but we want to apply the limit
1075 * to the currently queued data.
1076 */
1077 if (ctx->transport)
1078 sctp_transport_burst_limited(ctx->transport);
1079
1080 /* Finally, transmit new packets. */
1081 while ((chunk = sctp_outq_dequeue_data(ctx->q)) != NULL) {
1082 __u32 sid = ntohs(chunk->subh.data_hdr->stream);
1083 __u8 stream_state = SCTP_SO(&ctx->asoc->stream, sid)->state;
1084
1085 /* Has this chunk expired? */
1086 if (sctp_chunk_abandoned(chunk)) {
1087 sctp_sched_dequeue_done(ctx->q, chunk);
1088 sctp_chunk_fail(chunk, 0);
1089 sctp_chunk_free(chunk);
1090 continue;
1091 }
1092
1093 if (stream_state == SCTP_STREAM_CLOSED) {
1094 sctp_outq_head_data(ctx->q, chunk);
1095 break;
1096 }
1097
1098 sctp_outq_select_transport(ctx, chunk);
1099
1100 pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p skb->users:%d\n",
1101 __func__, ctx->q, chunk, chunk && chunk->chunk_hdr ?
1102 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
1103 "illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
1104 chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
1105 refcount_read(&chunk->skb->users) : -1);
1106
1107 /* Add the chunk to the packet. */
1108 status = sctp_packet_transmit_chunk(ctx->packet, chunk, 0,
1109 ctx->gfp);
1110 if (status != SCTP_XMIT_OK) {
1111 /* We could not append this chunk, so put
1112 * the chunk back on the output queue.
1113 */
1114 pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
1115 __func__, ntohl(chunk->subh.data_hdr->tsn),
1116 status);
1117
1118 sctp_outq_head_data(ctx->q, chunk);
1119 break;
1120 }
1121
1122 /* The sender is in the SHUTDOWN-PENDING state,
1123 * The sender MAY set the I-bit in the DATA
1124 * chunk header.
1125 */
1126 if (ctx->asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1127 chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1128 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
1129 ctx->asoc->stats.ouodchunks++;
1130 else
1131 ctx->asoc->stats.oodchunks++;
1132
1133 /* Only now it's safe to consider this
1134 * chunk as sent, sched-wise.
1135 */
1136 sctp_sched_dequeue_done(ctx->q, chunk);
1137
1138 list_add_tail(&chunk->transmitted_list,
1139 &ctx->transport->transmitted);
1140
1141 sctp_transport_reset_t3_rtx(ctx->transport);
1142 ctx->transport->last_time_sent = jiffies;
1143
1144 /* Only let one DATA chunk get bundled with a
1145 * COOKIE-ECHO chunk.
1146 */
1147 if (ctx->packet->has_cookie_echo)
1148 break;
1149 }
1150 }
1151
sctp_outq_flush_transports(struct sctp_flush_ctx * ctx)1152 static void sctp_outq_flush_transports(struct sctp_flush_ctx *ctx)
1153 {
1154 struct sock *sk = ctx->asoc->base.sk;
1155 struct list_head *ltransport;
1156 struct sctp_packet *packet;
1157 struct sctp_transport *t;
1158 int error = 0;
1159
1160 while ((ltransport = sctp_list_dequeue(&ctx->transport_list)) != NULL) {
1161 t = list_entry(ltransport, struct sctp_transport, send_ready);
1162 packet = &t->packet;
1163 if (!sctp_packet_empty(packet)) {
1164 rcu_read_lock();
1165 if (t->dst && __sk_dst_get(sk) != t->dst) {
1166 dst_hold(t->dst);
1167 sk_setup_caps(sk, t->dst);
1168 }
1169 rcu_read_unlock();
1170 error = sctp_packet_transmit(packet, ctx->gfp);
1171 if (error < 0)
1172 ctx->q->asoc->base.sk->sk_err = -error;
1173 }
1174
1175 /* Clear the burst limited state, if any */
1176 sctp_transport_burst_reset(t);
1177 }
1178 }
1179
1180 /* Try to flush an outqueue.
1181 *
1182 * Description: Send everything in q which we legally can, subject to
1183 * congestion limitations.
1184 * * Note: This function can be called from multiple contexts so appropriate
1185 * locking concerns must be made. Today we use the sock lock to protect
1186 * this function.
1187 */
1188
sctp_outq_flush(struct sctp_outq * q,int rtx_timeout,gfp_t gfp)1189 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
1190 {
1191 struct sctp_flush_ctx ctx = {
1192 .q = q,
1193 .transport = NULL,
1194 .transport_list = LIST_HEAD_INIT(ctx.transport_list),
1195 .asoc = q->asoc,
1196 .packet = NULL,
1197 .gfp = gfp,
1198 };
1199
1200 /* 6.10 Bundling
1201 * ...
1202 * When bundling control chunks with DATA chunks, an
1203 * endpoint MUST place control chunks first in the outbound
1204 * SCTP packet. The transmitter MUST transmit DATA chunks
1205 * within a SCTP packet in increasing order of TSN.
1206 * ...
1207 */
1208
1209 sctp_outq_flush_ctrl(&ctx);
1210
1211 if (q->asoc->src_out_of_asoc_ok)
1212 goto sctp_flush_out;
1213
1214 sctp_outq_flush_data(&ctx, rtx_timeout);
1215
1216 sctp_flush_out:
1217
1218 sctp_outq_flush_transports(&ctx);
1219 }
1220
1221 /* Update unack_data based on the incoming SACK chunk */
sctp_sack_update_unack_data(struct sctp_association * assoc,struct sctp_sackhdr * sack)1222 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1223 struct sctp_sackhdr *sack)
1224 {
1225 union sctp_sack_variable *frags;
1226 __u16 unack_data;
1227 int i;
1228
1229 unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1230
1231 frags = sack->variable;
1232 for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1233 unack_data -= ((ntohs(frags[i].gab.end) -
1234 ntohs(frags[i].gab.start) + 1));
1235 }
1236
1237 assoc->unack_data = unack_data;
1238 }
1239
1240 /* This is where we REALLY process a SACK.
1241 *
1242 * Process the SACK against the outqueue. Mostly, this just frees
1243 * things off the transmitted queue.
1244 */
sctp_outq_sack(struct sctp_outq * q,struct sctp_chunk * chunk)1245 int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1246 {
1247 struct sctp_association *asoc = q->asoc;
1248 struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1249 struct sctp_transport *transport;
1250 struct sctp_chunk *tchunk = NULL;
1251 struct list_head *lchunk, *transport_list, *temp;
1252 union sctp_sack_variable *frags = sack->variable;
1253 __u32 sack_ctsn, ctsn, tsn;
1254 __u32 highest_tsn, highest_new_tsn;
1255 __u32 sack_a_rwnd;
1256 unsigned int outstanding;
1257 struct sctp_transport *primary = asoc->peer.primary_path;
1258 int count_of_newacks = 0;
1259 int gap_ack_blocks;
1260 u8 accum_moved = 0;
1261
1262 /* Grab the association's destination address list. */
1263 transport_list = &asoc->peer.transport_addr_list;
1264
1265 /* SCTP path tracepoint for congestion control debugging. */
1266 if (trace_sctp_probe_path_enabled()) {
1267 list_for_each_entry(transport, transport_list, transports)
1268 trace_sctp_probe_path(transport, asoc);
1269 }
1270
1271 sack_ctsn = ntohl(sack->cum_tsn_ack);
1272 gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1273 asoc->stats.gapcnt += gap_ack_blocks;
1274 /*
1275 * SFR-CACC algorithm:
1276 * On receipt of a SACK the sender SHOULD execute the
1277 * following statements.
1278 *
1279 * 1) If the cumulative ack in the SACK passes next tsn_at_change
1280 * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1281 * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1282 * all destinations.
1283 * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1284 * is set the receiver of the SACK MUST take the following actions:
1285 *
1286 * A) Initialize the cacc_saw_newack to 0 for all destination
1287 * addresses.
1288 *
1289 * Only bother if changeover_active is set. Otherwise, this is
1290 * totally suboptimal to do on every SACK.
1291 */
1292 if (primary->cacc.changeover_active) {
1293 u8 clear_cycling = 0;
1294
1295 if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1296 primary->cacc.changeover_active = 0;
1297 clear_cycling = 1;
1298 }
1299
1300 if (clear_cycling || gap_ack_blocks) {
1301 list_for_each_entry(transport, transport_list,
1302 transports) {
1303 if (clear_cycling)
1304 transport->cacc.cycling_changeover = 0;
1305 if (gap_ack_blocks)
1306 transport->cacc.cacc_saw_newack = 0;
1307 }
1308 }
1309 }
1310
1311 /* Get the highest TSN in the sack. */
1312 highest_tsn = sack_ctsn;
1313 if (gap_ack_blocks)
1314 highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1315
1316 if (TSN_lt(asoc->highest_sacked, highest_tsn))
1317 asoc->highest_sacked = highest_tsn;
1318
1319 highest_new_tsn = sack_ctsn;
1320
1321 /* Run through the retransmit queue. Credit bytes received
1322 * and free those chunks that we can.
1323 */
1324 sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1325
1326 /* Run through the transmitted queue.
1327 * Credit bytes received and free those chunks which we can.
1328 *
1329 * This is a MASSIVE candidate for optimization.
1330 */
1331 list_for_each_entry(transport, transport_list, transports) {
1332 sctp_check_transmitted(q, &transport->transmitted,
1333 transport, &chunk->source, sack,
1334 &highest_new_tsn);
1335 /*
1336 * SFR-CACC algorithm:
1337 * C) Let count_of_newacks be the number of
1338 * destinations for which cacc_saw_newack is set.
1339 */
1340 if (transport->cacc.cacc_saw_newack)
1341 count_of_newacks++;
1342 }
1343
1344 /* Move the Cumulative TSN Ack Point if appropriate. */
1345 if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1346 asoc->ctsn_ack_point = sack_ctsn;
1347 accum_moved = 1;
1348 }
1349
1350 if (gap_ack_blocks) {
1351
1352 if (asoc->fast_recovery && accum_moved)
1353 highest_new_tsn = highest_tsn;
1354
1355 list_for_each_entry(transport, transport_list, transports)
1356 sctp_mark_missing(q, &transport->transmitted, transport,
1357 highest_new_tsn, count_of_newacks);
1358 }
1359
1360 /* Update unack_data field in the assoc. */
1361 sctp_sack_update_unack_data(asoc, sack);
1362
1363 ctsn = asoc->ctsn_ack_point;
1364
1365 /* Throw away stuff rotting on the sack queue. */
1366 list_for_each_safe(lchunk, temp, &q->sacked) {
1367 tchunk = list_entry(lchunk, struct sctp_chunk,
1368 transmitted_list);
1369 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1370 if (TSN_lte(tsn, ctsn)) {
1371 list_del_init(&tchunk->transmitted_list);
1372 if (asoc->peer.prsctp_capable &&
1373 SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
1374 asoc->sent_cnt_removable--;
1375 sctp_chunk_free(tchunk);
1376 }
1377 }
1378
1379 /* ii) Set rwnd equal to the newly received a_rwnd minus the
1380 * number of bytes still outstanding after processing the
1381 * Cumulative TSN Ack and the Gap Ack Blocks.
1382 */
1383
1384 sack_a_rwnd = ntohl(sack->a_rwnd);
1385 asoc->peer.zero_window_announced = !sack_a_rwnd;
1386 outstanding = q->outstanding_bytes;
1387
1388 if (outstanding < sack_a_rwnd)
1389 sack_a_rwnd -= outstanding;
1390 else
1391 sack_a_rwnd = 0;
1392
1393 asoc->peer.rwnd = sack_a_rwnd;
1394
1395 asoc->stream.si->generate_ftsn(q, sack_ctsn);
1396
1397 pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
1398 pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
1399 "advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
1400 asoc->adv_peer_ack_point);
1401
1402 return sctp_outq_is_empty(q);
1403 }
1404
1405 /* Is the outqueue empty?
1406 * The queue is empty when we have not pending data, no in-flight data
1407 * and nothing pending retransmissions.
1408 */
sctp_outq_is_empty(const struct sctp_outq * q)1409 int sctp_outq_is_empty(const struct sctp_outq *q)
1410 {
1411 return q->out_qlen == 0 && q->outstanding_bytes == 0 &&
1412 list_empty(&q->retransmit);
1413 }
1414
1415 /********************************************************************
1416 * 2nd Level Abstractions
1417 ********************************************************************/
1418
1419 /* Go through a transport's transmitted list or the association's retransmit
1420 * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1421 * The retransmit list will not have an associated transport.
1422 *
1423 * I added coherent debug information output. --xguo
1424 *
1425 * Instead of printing 'sacked' or 'kept' for each TSN on the
1426 * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1427 * KEPT TSN6-TSN7, etc.
1428 */
sctp_check_transmitted(struct sctp_outq * q,struct list_head * transmitted_queue,struct sctp_transport * transport,union sctp_addr * saddr,struct sctp_sackhdr * sack,__u32 * highest_new_tsn_in_sack)1429 static void sctp_check_transmitted(struct sctp_outq *q,
1430 struct list_head *transmitted_queue,
1431 struct sctp_transport *transport,
1432 union sctp_addr *saddr,
1433 struct sctp_sackhdr *sack,
1434 __u32 *highest_new_tsn_in_sack)
1435 {
1436 struct list_head *lchunk;
1437 struct sctp_chunk *tchunk;
1438 struct list_head tlist;
1439 __u32 tsn;
1440 __u32 sack_ctsn;
1441 __u32 rtt;
1442 __u8 restart_timer = 0;
1443 int bytes_acked = 0;
1444 int migrate_bytes = 0;
1445 bool forward_progress = false;
1446
1447 sack_ctsn = ntohl(sack->cum_tsn_ack);
1448
1449 INIT_LIST_HEAD(&tlist);
1450
1451 /* The while loop will skip empty transmitted queues. */
1452 while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1453 tchunk = list_entry(lchunk, struct sctp_chunk,
1454 transmitted_list);
1455
1456 if (sctp_chunk_abandoned(tchunk)) {
1457 /* Move the chunk to abandoned list. */
1458 sctp_insert_list(&q->abandoned, lchunk);
1459
1460 /* If this chunk has not been acked, stop
1461 * considering it as 'outstanding'.
1462 */
1463 if (transmitted_queue != &q->retransmit &&
1464 !tchunk->tsn_gap_acked) {
1465 if (tchunk->transport)
1466 tchunk->transport->flight_size -=
1467 sctp_data_size(tchunk);
1468 q->outstanding_bytes -= sctp_data_size(tchunk);
1469 }
1470 continue;
1471 }
1472
1473 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1474 if (sctp_acked(sack, tsn)) {
1475 /* If this queue is the retransmit queue, the
1476 * retransmit timer has already reclaimed
1477 * the outstanding bytes for this chunk, so only
1478 * count bytes associated with a transport.
1479 */
1480 if (transport && !tchunk->tsn_gap_acked) {
1481 /* If this chunk is being used for RTT
1482 * measurement, calculate the RTT and update
1483 * the RTO using this value.
1484 *
1485 * 6.3.1 C5) Karn's algorithm: RTT measurements
1486 * MUST NOT be made using packets that were
1487 * retransmitted (and thus for which it is
1488 * ambiguous whether the reply was for the
1489 * first instance of the packet or a later
1490 * instance).
1491 */
1492 if (!sctp_chunk_retransmitted(tchunk) &&
1493 tchunk->rtt_in_progress) {
1494 tchunk->rtt_in_progress = 0;
1495 rtt = jiffies - tchunk->sent_at;
1496 sctp_transport_update_rto(transport,
1497 rtt);
1498 }
1499
1500 if (TSN_lte(tsn, sack_ctsn)) {
1501 /*
1502 * SFR-CACC algorithm:
1503 * 2) If the SACK contains gap acks
1504 * and the flag CHANGEOVER_ACTIVE is
1505 * set the receiver of the SACK MUST
1506 * take the following action:
1507 *
1508 * B) For each TSN t being acked that
1509 * has not been acked in any SACK so
1510 * far, set cacc_saw_newack to 1 for
1511 * the destination that the TSN was
1512 * sent to.
1513 */
1514 if (sack->num_gap_ack_blocks &&
1515 q->asoc->peer.primary_path->cacc.
1516 changeover_active)
1517 transport->cacc.cacc_saw_newack
1518 = 1;
1519 }
1520 }
1521
1522 /* If the chunk hasn't been marked as ACKED,
1523 * mark it and account bytes_acked if the
1524 * chunk had a valid transport (it will not
1525 * have a transport if ASCONF had deleted it
1526 * while DATA was outstanding).
1527 */
1528 if (!tchunk->tsn_gap_acked) {
1529 tchunk->tsn_gap_acked = 1;
1530 if (TSN_lt(*highest_new_tsn_in_sack, tsn))
1531 *highest_new_tsn_in_sack = tsn;
1532 bytes_acked += sctp_data_size(tchunk);
1533 if (!tchunk->transport)
1534 migrate_bytes += sctp_data_size(tchunk);
1535 forward_progress = true;
1536 }
1537
1538 if (TSN_lte(tsn, sack_ctsn)) {
1539 /* RFC 2960 6.3.2 Retransmission Timer Rules
1540 *
1541 * R3) Whenever a SACK is received
1542 * that acknowledges the DATA chunk
1543 * with the earliest outstanding TSN
1544 * for that address, restart T3-rtx
1545 * timer for that address with its
1546 * current RTO.
1547 */
1548 restart_timer = 1;
1549 forward_progress = true;
1550
1551 list_add_tail(&tchunk->transmitted_list,
1552 &q->sacked);
1553 } else {
1554 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1555 * M2) Each time a SACK arrives reporting
1556 * 'Stray DATA chunk(s)' record the highest TSN
1557 * reported as newly acknowledged, call this
1558 * value 'HighestTSNinSack'. A newly
1559 * acknowledged DATA chunk is one not
1560 * previously acknowledged in a SACK.
1561 *
1562 * When the SCTP sender of data receives a SACK
1563 * chunk that acknowledges, for the first time,
1564 * the receipt of a DATA chunk, all the still
1565 * unacknowledged DATA chunks whose TSN is
1566 * older than that newly acknowledged DATA
1567 * chunk, are qualified as 'Stray DATA chunks'.
1568 */
1569 list_add_tail(lchunk, &tlist);
1570 }
1571 } else {
1572 if (tchunk->tsn_gap_acked) {
1573 pr_debug("%s: receiver reneged on data TSN:0x%x\n",
1574 __func__, tsn);
1575
1576 tchunk->tsn_gap_acked = 0;
1577
1578 if (tchunk->transport)
1579 bytes_acked -= sctp_data_size(tchunk);
1580
1581 /* RFC 2960 6.3.2 Retransmission Timer Rules
1582 *
1583 * R4) Whenever a SACK is received missing a
1584 * TSN that was previously acknowledged via a
1585 * Gap Ack Block, start T3-rtx for the
1586 * destination address to which the DATA
1587 * chunk was originally
1588 * transmitted if it is not already running.
1589 */
1590 restart_timer = 1;
1591 }
1592
1593 list_add_tail(lchunk, &tlist);
1594 }
1595 }
1596
1597 if (transport) {
1598 if (bytes_acked) {
1599 struct sctp_association *asoc = transport->asoc;
1600
1601 /* We may have counted DATA that was migrated
1602 * to this transport due to DEL-IP operation.
1603 * Subtract those bytes, since the were never
1604 * send on this transport and shouldn't be
1605 * credited to this transport.
1606 */
1607 bytes_acked -= migrate_bytes;
1608
1609 /* 8.2. When an outstanding TSN is acknowledged,
1610 * the endpoint shall clear the error counter of
1611 * the destination transport address to which the
1612 * DATA chunk was last sent.
1613 * The association's overall error counter is
1614 * also cleared.
1615 */
1616 transport->error_count = 0;
1617 transport->asoc->overall_error_count = 0;
1618 forward_progress = true;
1619
1620 /*
1621 * While in SHUTDOWN PENDING, we may have started
1622 * the T5 shutdown guard timer after reaching the
1623 * retransmission limit. Stop that timer as soon
1624 * as the receiver acknowledged any data.
1625 */
1626 if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1627 del_timer(&asoc->timers
1628 [SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1629 sctp_association_put(asoc);
1630
1631 /* Mark the destination transport address as
1632 * active if it is not so marked.
1633 */
1634 if ((transport->state == SCTP_INACTIVE ||
1635 transport->state == SCTP_UNCONFIRMED) &&
1636 sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1637 sctp_assoc_control_transport(
1638 transport->asoc,
1639 transport,
1640 SCTP_TRANSPORT_UP,
1641 SCTP_RECEIVED_SACK);
1642 }
1643
1644 sctp_transport_raise_cwnd(transport, sack_ctsn,
1645 bytes_acked);
1646
1647 transport->flight_size -= bytes_acked;
1648 if (transport->flight_size == 0)
1649 transport->partial_bytes_acked = 0;
1650 q->outstanding_bytes -= bytes_acked + migrate_bytes;
1651 } else {
1652 /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1653 * When a sender is doing zero window probing, it
1654 * should not timeout the association if it continues
1655 * to receive new packets from the receiver. The
1656 * reason is that the receiver MAY keep its window
1657 * closed for an indefinite time.
1658 * A sender is doing zero window probing when the
1659 * receiver's advertised window is zero, and there is
1660 * only one data chunk in flight to the receiver.
1661 *
1662 * Allow the association to timeout while in SHUTDOWN
1663 * PENDING or SHUTDOWN RECEIVED in case the receiver
1664 * stays in zero window mode forever.
1665 */
1666 if (!q->asoc->peer.rwnd &&
1667 !list_empty(&tlist) &&
1668 (sack_ctsn+2 == q->asoc->next_tsn) &&
1669 q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1670 pr_debug("%s: sack received for zero window "
1671 "probe:%u\n", __func__, sack_ctsn);
1672
1673 q->asoc->overall_error_count = 0;
1674 transport->error_count = 0;
1675 }
1676 }
1677
1678 /* RFC 2960 6.3.2 Retransmission Timer Rules
1679 *
1680 * R2) Whenever all outstanding data sent to an address have
1681 * been acknowledged, turn off the T3-rtx timer of that
1682 * address.
1683 */
1684 if (!transport->flight_size) {
1685 if (del_timer(&transport->T3_rtx_timer))
1686 sctp_transport_put(transport);
1687 } else if (restart_timer) {
1688 if (!mod_timer(&transport->T3_rtx_timer,
1689 jiffies + transport->rto))
1690 sctp_transport_hold(transport);
1691 }
1692
1693 if (forward_progress) {
1694 if (transport->dst)
1695 sctp_transport_dst_confirm(transport);
1696 }
1697 }
1698
1699 list_splice(&tlist, transmitted_queue);
1700 }
1701
1702 /* Mark chunks as missing and consequently may get retransmitted. */
sctp_mark_missing(struct sctp_outq * q,struct list_head * transmitted_queue,struct sctp_transport * transport,__u32 highest_new_tsn_in_sack,int count_of_newacks)1703 static void sctp_mark_missing(struct sctp_outq *q,
1704 struct list_head *transmitted_queue,
1705 struct sctp_transport *transport,
1706 __u32 highest_new_tsn_in_sack,
1707 int count_of_newacks)
1708 {
1709 struct sctp_chunk *chunk;
1710 __u32 tsn;
1711 char do_fast_retransmit = 0;
1712 struct sctp_association *asoc = q->asoc;
1713 struct sctp_transport *primary = asoc->peer.primary_path;
1714
1715 list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1716
1717 tsn = ntohl(chunk->subh.data_hdr->tsn);
1718
1719 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1720 * 'Unacknowledged TSN's', if the TSN number of an
1721 * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1722 * value, increment the 'TSN.Missing.Report' count on that
1723 * chunk if it has NOT been fast retransmitted or marked for
1724 * fast retransmit already.
1725 */
1726 if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1727 !chunk->tsn_gap_acked &&
1728 TSN_lt(tsn, highest_new_tsn_in_sack)) {
1729
1730 /* SFR-CACC may require us to skip marking
1731 * this chunk as missing.
1732 */
1733 if (!transport || !sctp_cacc_skip(primary,
1734 chunk->transport,
1735 count_of_newacks, tsn)) {
1736 chunk->tsn_missing_report++;
1737
1738 pr_debug("%s: tsn:0x%x missing counter:%d\n",
1739 __func__, tsn, chunk->tsn_missing_report);
1740 }
1741 }
1742 /*
1743 * M4) If any DATA chunk is found to have a
1744 * 'TSN.Missing.Report'
1745 * value larger than or equal to 3, mark that chunk for
1746 * retransmission and start the fast retransmit procedure.
1747 */
1748
1749 if (chunk->tsn_missing_report >= 3) {
1750 chunk->fast_retransmit = SCTP_NEED_FRTX;
1751 do_fast_retransmit = 1;
1752 }
1753 }
1754
1755 if (transport) {
1756 if (do_fast_retransmit)
1757 sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1758
1759 pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
1760 "flight_size:%d, pba:%d\n", __func__, transport,
1761 transport->cwnd, transport->ssthresh,
1762 transport->flight_size, transport->partial_bytes_acked);
1763 }
1764 }
1765
1766 /* Is the given TSN acked by this packet? */
sctp_acked(struct sctp_sackhdr * sack,__u32 tsn)1767 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1768 {
1769 __u32 ctsn = ntohl(sack->cum_tsn_ack);
1770 union sctp_sack_variable *frags;
1771 __u16 tsn_offset, blocks;
1772 int i;
1773
1774 if (TSN_lte(tsn, ctsn))
1775 goto pass;
1776
1777 /* 3.3.4 Selective Acknowledgment (SACK) (3):
1778 *
1779 * Gap Ack Blocks:
1780 * These fields contain the Gap Ack Blocks. They are repeated
1781 * for each Gap Ack Block up to the number of Gap Ack Blocks
1782 * defined in the Number of Gap Ack Blocks field. All DATA
1783 * chunks with TSNs greater than or equal to (Cumulative TSN
1784 * Ack + Gap Ack Block Start) and less than or equal to
1785 * (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1786 * Block are assumed to have been received correctly.
1787 */
1788
1789 frags = sack->variable;
1790 blocks = ntohs(sack->num_gap_ack_blocks);
1791 tsn_offset = tsn - ctsn;
1792 for (i = 0; i < blocks; ++i) {
1793 if (tsn_offset >= ntohs(frags[i].gab.start) &&
1794 tsn_offset <= ntohs(frags[i].gab.end))
1795 goto pass;
1796 }
1797
1798 return 0;
1799 pass:
1800 return 1;
1801 }
1802
sctp_get_skip_pos(struct sctp_fwdtsn_skip * skiplist,int nskips,__be16 stream)1803 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1804 int nskips, __be16 stream)
1805 {
1806 int i;
1807
1808 for (i = 0; i < nskips; i++) {
1809 if (skiplist[i].stream == stream)
1810 return i;
1811 }
1812 return i;
1813 }
1814
1815 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
sctp_generate_fwdtsn(struct sctp_outq * q,__u32 ctsn)1816 void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1817 {
1818 struct sctp_association *asoc = q->asoc;
1819 struct sctp_chunk *ftsn_chunk = NULL;
1820 struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1821 int nskips = 0;
1822 int skip_pos = 0;
1823 __u32 tsn;
1824 struct sctp_chunk *chunk;
1825 struct list_head *lchunk, *temp;
1826
1827 if (!asoc->peer.prsctp_capable)
1828 return;
1829
1830 /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1831 * received SACK.
1832 *
1833 * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1834 * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1835 */
1836 if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1837 asoc->adv_peer_ack_point = ctsn;
1838
1839 /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1840 * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1841 * the chunk next in the out-queue space is marked as "abandoned" as
1842 * shown in the following example:
1843 *
1844 * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1845 * and the Advanced.Peer.Ack.Point is updated to this value:
1846 *
1847 * out-queue at the end of ==> out-queue after Adv.Ack.Point
1848 * normal SACK processing local advancement
1849 * ... ...
1850 * Adv.Ack.Pt-> 102 acked 102 acked
1851 * 103 abandoned 103 abandoned
1852 * 104 abandoned Adv.Ack.P-> 104 abandoned
1853 * 105 105
1854 * 106 acked 106 acked
1855 * ... ...
1856 *
1857 * In this example, the data sender successfully advanced the
1858 * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1859 */
1860 list_for_each_safe(lchunk, temp, &q->abandoned) {
1861 chunk = list_entry(lchunk, struct sctp_chunk,
1862 transmitted_list);
1863 tsn = ntohl(chunk->subh.data_hdr->tsn);
1864
1865 /* Remove any chunks in the abandoned queue that are acked by
1866 * the ctsn.
1867 */
1868 if (TSN_lte(tsn, ctsn)) {
1869 list_del_init(lchunk);
1870 sctp_chunk_free(chunk);
1871 } else {
1872 if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1873 asoc->adv_peer_ack_point = tsn;
1874 if (chunk->chunk_hdr->flags &
1875 SCTP_DATA_UNORDERED)
1876 continue;
1877 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1878 nskips,
1879 chunk->subh.data_hdr->stream);
1880 ftsn_skip_arr[skip_pos].stream =
1881 chunk->subh.data_hdr->stream;
1882 ftsn_skip_arr[skip_pos].ssn =
1883 chunk->subh.data_hdr->ssn;
1884 if (skip_pos == nskips)
1885 nskips++;
1886 if (nskips == 10)
1887 break;
1888 } else
1889 break;
1890 }
1891 }
1892
1893 /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1894 * is greater than the Cumulative TSN ACK carried in the received
1895 * SACK, the data sender MUST send the data receiver a FORWARD TSN
1896 * chunk containing the latest value of the
1897 * "Advanced.Peer.Ack.Point".
1898 *
1899 * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1900 * list each stream and sequence number in the forwarded TSN. This
1901 * information will enable the receiver to easily find any
1902 * stranded TSN's waiting on stream reorder queues. Each stream
1903 * SHOULD only be reported once; this means that if multiple
1904 * abandoned messages occur in the same stream then only the
1905 * highest abandoned stream sequence number is reported. If the
1906 * total size of the FORWARD TSN does NOT fit in a single MTU then
1907 * the sender of the FORWARD TSN SHOULD lower the
1908 * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1909 * single MTU.
1910 */
1911 if (asoc->adv_peer_ack_point > ctsn)
1912 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1913 nskips, &ftsn_skip_arr[0]);
1914
1915 if (ftsn_chunk) {
1916 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1917 SCTP_INC_STATS(asoc->base.net, SCTP_MIB_OUTCTRLCHUNKS);
1918 }
1919 }
1920