Merge tag 'nfs-for-5.1-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
[linux-2.6-microblaze.git] / net / sctp / outqueue.c
1 /* SCTP kernel implementation
2  * (C) Copyright IBM Corp. 2001, 2004
3  * Copyright (c) 1999-2000 Cisco, Inc.
4  * Copyright (c) 1999-2001 Motorola, Inc.
5  * Copyright (c) 2001-2003 Intel Corp.
6  *
7  * This file is part of the SCTP kernel implementation
8  *
9  * These functions implement the sctp_outq class.   The outqueue handles
10  * bundling and queueing of outgoing SCTP chunks.
11  *
12  * This SCTP implementation is free software;
13  * you can redistribute it and/or modify it under the terms of
14  * the GNU General Public License as published by
15  * the Free Software Foundation; either version 2, or (at your option)
16  * any later version.
17  *
18  * This SCTP implementation is distributed in the hope that it
19  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
20  *                 ************************
21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
22  * See the GNU General Public License for more details.
23  *
24  * You should have received a copy of the GNU General Public License
25  * along with GNU CC; see the file COPYING.  If not, see
26  * <http://www.gnu.org/licenses/>.
27  *
28  * Please send any bug reports or fixes you make to the
29  * email address(es):
30  *    lksctp developers <linux-sctp@vger.kernel.org>
31  *
32  * Written or modified by:
33  *    La Monte H.P. Yarroll <piggy@acm.org>
34  *    Karl Knutson          <karl@athena.chicago.il.us>
35  *    Perry Melange         <pmelange@null.cc.uic.edu>
36  *    Xingang Guo           <xingang.guo@intel.com>
37  *    Hui Huang             <hui.huang@nokia.com>
38  *    Sridhar Samudrala     <sri@us.ibm.com>
39  *    Jon Grimm             <jgrimm@us.ibm.com>
40  */
41
42 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
43
44 #include <linux/types.h>
45 #include <linux/list.h>   /* For struct list_head */
46 #include <linux/socket.h>
47 #include <linux/ip.h>
48 #include <linux/slab.h>
49 #include <net/sock.h>     /* For skb_set_owner_w */
50
51 #include <net/sctp/sctp.h>
52 #include <net/sctp/sm.h>
53 #include <net/sctp/stream_sched.h>
54
55 /* Declare internal functions here.  */
56 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
57 static void sctp_check_transmitted(struct sctp_outq *q,
58                                    struct list_head *transmitted_queue,
59                                    struct sctp_transport *transport,
60                                    union sctp_addr *saddr,
61                                    struct sctp_sackhdr *sack,
62                                    __u32 *highest_new_tsn);
63
64 static void sctp_mark_missing(struct sctp_outq *q,
65                               struct list_head *transmitted_queue,
66                               struct sctp_transport *transport,
67                               __u32 highest_new_tsn,
68                               int count_of_newacks);
69
70 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp);
71
72 /* Add data to the front of the queue. */
73 static inline void sctp_outq_head_data(struct sctp_outq *q,
74                                        struct sctp_chunk *ch)
75 {
76         struct sctp_stream_out_ext *oute;
77         __u16 stream;
78
79         list_add(&ch->list, &q->out_chunk_list);
80         q->out_qlen += ch->skb->len;
81
82         stream = sctp_chunk_stream_no(ch);
83         oute = SCTP_SO(&q->asoc->stream, stream)->ext;
84         list_add(&ch->stream_list, &oute->outq);
85 }
86
87 /* Take data from the front of the queue. */
88 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
89 {
90         return q->sched->dequeue(q);
91 }
92
93 /* Add data chunk to the end of the queue. */
94 static inline void sctp_outq_tail_data(struct sctp_outq *q,
95                                        struct sctp_chunk *ch)
96 {
97         struct sctp_stream_out_ext *oute;
98         __u16 stream;
99
100         list_add_tail(&ch->list, &q->out_chunk_list);
101         q->out_qlen += ch->skb->len;
102
103         stream = sctp_chunk_stream_no(ch);
104         oute = SCTP_SO(&q->asoc->stream, stream)->ext;
105         list_add_tail(&ch->stream_list, &oute->outq);
106 }
107
108 /*
109  * SFR-CACC algorithm:
110  * D) If count_of_newacks is greater than or equal to 2
111  * and t was not sent to the current primary then the
112  * sender MUST NOT increment missing report count for t.
113  */
114 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
115                                        struct sctp_transport *transport,
116                                        int count_of_newacks)
117 {
118         if (count_of_newacks >= 2 && transport != primary)
119                 return 1;
120         return 0;
121 }
122
123 /*
124  * SFR-CACC algorithm:
125  * F) If count_of_newacks is less than 2, let d be the
126  * destination to which t was sent. If cacc_saw_newack
127  * is 0 for destination d, then the sender MUST NOT
128  * increment missing report count for t.
129  */
130 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
131                                        int count_of_newacks)
132 {
133         if (count_of_newacks < 2 &&
134                         (transport && !transport->cacc.cacc_saw_newack))
135                 return 1;
136         return 0;
137 }
138
139 /*
140  * SFR-CACC algorithm:
141  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
142  * execute steps C, D, F.
143  *
144  * C has been implemented in sctp_outq_sack
145  */
146 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
147                                      struct sctp_transport *transport,
148                                      int count_of_newacks)
149 {
150         if (!primary->cacc.cycling_changeover) {
151                 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
152                         return 1;
153                 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
154                         return 1;
155                 return 0;
156         }
157         return 0;
158 }
159
160 /*
161  * SFR-CACC algorithm:
162  * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
163  * than next_tsn_at_change of the current primary, then
164  * the sender MUST NOT increment missing report count
165  * for t.
166  */
167 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
168 {
169         if (primary->cacc.cycling_changeover &&
170             TSN_lt(tsn, primary->cacc.next_tsn_at_change))
171                 return 1;
172         return 0;
173 }
174
175 /*
176  * SFR-CACC algorithm:
177  * 3) If the missing report count for TSN t is to be
178  * incremented according to [RFC2960] and
179  * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
180  * then the sender MUST further execute steps 3.1 and
181  * 3.2 to determine if the missing report count for
182  * TSN t SHOULD NOT be incremented.
183  *
184  * 3.3) If 3.1 and 3.2 do not dictate that the missing
185  * report count for t should not be incremented, then
186  * the sender SHOULD increment missing report count for
187  * t (according to [RFC2960] and [SCTP_STEWART_2002]).
188  */
189 static inline int sctp_cacc_skip(struct sctp_transport *primary,
190                                  struct sctp_transport *transport,
191                                  int count_of_newacks,
192                                  __u32 tsn)
193 {
194         if (primary->cacc.changeover_active &&
195             (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
196              sctp_cacc_skip_3_2(primary, tsn)))
197                 return 1;
198         return 0;
199 }
200
201 /* Initialize an existing sctp_outq.  This does the boring stuff.
202  * You still need to define handlers if you really want to DO
203  * something with this structure...
204  */
205 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
206 {
207         memset(q, 0, sizeof(struct sctp_outq));
208
209         q->asoc = asoc;
210         INIT_LIST_HEAD(&q->out_chunk_list);
211         INIT_LIST_HEAD(&q->control_chunk_list);
212         INIT_LIST_HEAD(&q->retransmit);
213         INIT_LIST_HEAD(&q->sacked);
214         INIT_LIST_HEAD(&q->abandoned);
215         sctp_sched_set_sched(asoc, sctp_sk(asoc->base.sk)->default_ss);
216 }
217
218 /* Free the outqueue structure and any related pending chunks.
219  */
220 static void __sctp_outq_teardown(struct sctp_outq *q)
221 {
222         struct sctp_transport *transport;
223         struct list_head *lchunk, *temp;
224         struct sctp_chunk *chunk, *tmp;
225
226         /* Throw away unacknowledged chunks. */
227         list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
228                         transports) {
229                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
230                         chunk = list_entry(lchunk, struct sctp_chunk,
231                                            transmitted_list);
232                         /* Mark as part of a failed message. */
233                         sctp_chunk_fail(chunk, q->error);
234                         sctp_chunk_free(chunk);
235                 }
236         }
237
238         /* Throw away chunks that have been gap ACKed.  */
239         list_for_each_safe(lchunk, temp, &q->sacked) {
240                 list_del_init(lchunk);
241                 chunk = list_entry(lchunk, struct sctp_chunk,
242                                    transmitted_list);
243                 sctp_chunk_fail(chunk, q->error);
244                 sctp_chunk_free(chunk);
245         }
246
247         /* Throw away any chunks in the retransmit queue. */
248         list_for_each_safe(lchunk, temp, &q->retransmit) {
249                 list_del_init(lchunk);
250                 chunk = list_entry(lchunk, struct sctp_chunk,
251                                    transmitted_list);
252                 sctp_chunk_fail(chunk, q->error);
253                 sctp_chunk_free(chunk);
254         }
255
256         /* Throw away any chunks that are in the abandoned queue. */
257         list_for_each_safe(lchunk, temp, &q->abandoned) {
258                 list_del_init(lchunk);
259                 chunk = list_entry(lchunk, struct sctp_chunk,
260                                    transmitted_list);
261                 sctp_chunk_fail(chunk, q->error);
262                 sctp_chunk_free(chunk);
263         }
264
265         /* Throw away any leftover data chunks. */
266         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
267                 sctp_sched_dequeue_done(q, chunk);
268
269                 /* Mark as send failure. */
270                 sctp_chunk_fail(chunk, q->error);
271                 sctp_chunk_free(chunk);
272         }
273
274         /* Throw away any leftover control chunks. */
275         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
276                 list_del_init(&chunk->list);
277                 sctp_chunk_free(chunk);
278         }
279 }
280
281 void sctp_outq_teardown(struct sctp_outq *q)
282 {
283         __sctp_outq_teardown(q);
284         sctp_outq_init(q->asoc, q);
285 }
286
287 /* Free the outqueue structure and any related pending chunks.  */
288 void sctp_outq_free(struct sctp_outq *q)
289 {
290         /* Throw away leftover chunks. */
291         __sctp_outq_teardown(q);
292 }
293
294 /* Put a new chunk in an sctp_outq.  */
295 void sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk, gfp_t gfp)
296 {
297         struct net *net = sock_net(q->asoc->base.sk);
298
299         pr_debug("%s: outq:%p, chunk:%p[%s]\n", __func__, q, chunk,
300                  chunk && chunk->chunk_hdr ?
301                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
302                  "illegal chunk");
303
304         /* If it is data, queue it up, otherwise, send it
305          * immediately.
306          */
307         if (sctp_chunk_is_data(chunk)) {
308                 pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
309                          __func__, q, chunk, chunk && chunk->chunk_hdr ?
310                          sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
311                          "illegal chunk");
312
313                 sctp_outq_tail_data(q, chunk);
314                 if (chunk->asoc->peer.prsctp_capable &&
315                     SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
316                         chunk->asoc->sent_cnt_removable++;
317                 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
318                         SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
319                 else
320                         SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
321         } else {
322                 list_add_tail(&chunk->list, &q->control_chunk_list);
323                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
324         }
325
326         if (!q->cork)
327                 sctp_outq_flush(q, 0, gfp);
328 }
329
330 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
331  * and the abandoned list are in ascending order.
332  */
333 static void sctp_insert_list(struct list_head *head, struct list_head *new)
334 {
335         struct list_head *pos;
336         struct sctp_chunk *nchunk, *lchunk;
337         __u32 ntsn, ltsn;
338         int done = 0;
339
340         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
341         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
342
343         list_for_each(pos, head) {
344                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
345                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
346                 if (TSN_lt(ntsn, ltsn)) {
347                         list_add(new, pos->prev);
348                         done = 1;
349                         break;
350                 }
351         }
352         if (!done)
353                 list_add_tail(new, head);
354 }
355
356 static int sctp_prsctp_prune_sent(struct sctp_association *asoc,
357                                   struct sctp_sndrcvinfo *sinfo,
358                                   struct list_head *queue, int msg_len)
359 {
360         struct sctp_chunk *chk, *temp;
361
362         list_for_each_entry_safe(chk, temp, queue, transmitted_list) {
363                 struct sctp_stream_out *streamout;
364
365                 if (!chk->msg->abandoned &&
366                     (!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
367                      chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
368                         continue;
369
370                 chk->msg->abandoned = 1;
371                 list_del_init(&chk->transmitted_list);
372                 sctp_insert_list(&asoc->outqueue.abandoned,
373                                  &chk->transmitted_list);
374
375                 streamout = SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
376                 asoc->sent_cnt_removable--;
377                 asoc->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
378                 streamout->ext->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
379
380                 if (queue != &asoc->outqueue.retransmit &&
381                     !chk->tsn_gap_acked) {
382                         if (chk->transport)
383                                 chk->transport->flight_size -=
384                                                 sctp_data_size(chk);
385                         asoc->outqueue.outstanding_bytes -= sctp_data_size(chk);
386                 }
387
388                 msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
389                 if (msg_len <= 0)
390                         break;
391         }
392
393         return msg_len;
394 }
395
396 static int sctp_prsctp_prune_unsent(struct sctp_association *asoc,
397                                     struct sctp_sndrcvinfo *sinfo, int msg_len)
398 {
399         struct sctp_outq *q = &asoc->outqueue;
400         struct sctp_chunk *chk, *temp;
401
402         q->sched->unsched_all(&asoc->stream);
403
404         list_for_each_entry_safe(chk, temp, &q->out_chunk_list, list) {
405                 if (!chk->msg->abandoned &&
406                     (!(chk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG) ||
407                      !SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
408                      chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
409                         continue;
410
411                 chk->msg->abandoned = 1;
412                 sctp_sched_dequeue_common(q, chk);
413                 asoc->sent_cnt_removable--;
414                 asoc->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
415                 if (chk->sinfo.sinfo_stream < asoc->stream.outcnt) {
416                         struct sctp_stream_out *streamout =
417                                 SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
418
419                         streamout->ext->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
420                 }
421
422                 msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
423                 sctp_chunk_free(chk);
424                 if (msg_len <= 0)
425                         break;
426         }
427
428         q->sched->sched_all(&asoc->stream);
429
430         return msg_len;
431 }
432
433 /* Abandon the chunks according their priorities */
434 void sctp_prsctp_prune(struct sctp_association *asoc,
435                        struct sctp_sndrcvinfo *sinfo, int msg_len)
436 {
437         struct sctp_transport *transport;
438
439         if (!asoc->peer.prsctp_capable || !asoc->sent_cnt_removable)
440                 return;
441
442         msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
443                                          &asoc->outqueue.retransmit,
444                                          msg_len);
445         if (msg_len <= 0)
446                 return;
447
448         list_for_each_entry(transport, &asoc->peer.transport_addr_list,
449                             transports) {
450                 msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
451                                                  &transport->transmitted,
452                                                  msg_len);
453                 if (msg_len <= 0)
454                         return;
455         }
456
457         sctp_prsctp_prune_unsent(asoc, sinfo, msg_len);
458 }
459
460 /* Mark all the eligible packets on a transport for retransmission.  */
461 void sctp_retransmit_mark(struct sctp_outq *q,
462                           struct sctp_transport *transport,
463                           __u8 reason)
464 {
465         struct list_head *lchunk, *ltemp;
466         struct sctp_chunk *chunk;
467
468         /* Walk through the specified transmitted queue.  */
469         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
470                 chunk = list_entry(lchunk, struct sctp_chunk,
471                                    transmitted_list);
472
473                 /* If the chunk is abandoned, move it to abandoned list. */
474                 if (sctp_chunk_abandoned(chunk)) {
475                         list_del_init(lchunk);
476                         sctp_insert_list(&q->abandoned, lchunk);
477
478                         /* If this chunk has not been previousely acked,
479                          * stop considering it 'outstanding'.  Our peer
480                          * will most likely never see it since it will
481                          * not be retransmitted
482                          */
483                         if (!chunk->tsn_gap_acked) {
484                                 if (chunk->transport)
485                                         chunk->transport->flight_size -=
486                                                         sctp_data_size(chunk);
487                                 q->outstanding_bytes -= sctp_data_size(chunk);
488                                 q->asoc->peer.rwnd += sctp_data_size(chunk);
489                         }
490                         continue;
491                 }
492
493                 /* If we are doing  retransmission due to a timeout or pmtu
494                  * discovery, only the  chunks that are not yet acked should
495                  * be added to the retransmit queue.
496                  */
497                 if ((reason == SCTP_RTXR_FAST_RTX  &&
498                             (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
499                     (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
500                         /* RFC 2960 6.2.1 Processing a Received SACK
501                          *
502                          * C) Any time a DATA chunk is marked for
503                          * retransmission (via either T3-rtx timer expiration
504                          * (Section 6.3.3) or via fast retransmit
505                          * (Section 7.2.4)), add the data size of those
506                          * chunks to the rwnd.
507                          */
508                         q->asoc->peer.rwnd += sctp_data_size(chunk);
509                         q->outstanding_bytes -= sctp_data_size(chunk);
510                         if (chunk->transport)
511                                 transport->flight_size -= sctp_data_size(chunk);
512
513                         /* sctpimpguide-05 Section 2.8.2
514                          * M5) If a T3-rtx timer expires, the
515                          * 'TSN.Missing.Report' of all affected TSNs is set
516                          * to 0.
517                          */
518                         chunk->tsn_missing_report = 0;
519
520                         /* If a chunk that is being used for RTT measurement
521                          * has to be retransmitted, we cannot use this chunk
522                          * anymore for RTT measurements. Reset rto_pending so
523                          * that a new RTT measurement is started when a new
524                          * data chunk is sent.
525                          */
526                         if (chunk->rtt_in_progress) {
527                                 chunk->rtt_in_progress = 0;
528                                 transport->rto_pending = 0;
529                         }
530
531                         /* Move the chunk to the retransmit queue. The chunks
532                          * on the retransmit queue are always kept in order.
533                          */
534                         list_del_init(lchunk);
535                         sctp_insert_list(&q->retransmit, lchunk);
536                 }
537         }
538
539         pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, "
540                  "flight_size:%d, pba:%d\n", __func__, transport, reason,
541                  transport->cwnd, transport->ssthresh, transport->flight_size,
542                  transport->partial_bytes_acked);
543 }
544
545 /* Mark all the eligible packets on a transport for retransmission and force
546  * one packet out.
547  */
548 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
549                      enum sctp_retransmit_reason reason)
550 {
551         struct net *net = sock_net(q->asoc->base.sk);
552
553         switch (reason) {
554         case SCTP_RTXR_T3_RTX:
555                 SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
556                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
557                 /* Update the retran path if the T3-rtx timer has expired for
558                  * the current retran path.
559                  */
560                 if (transport == transport->asoc->peer.retran_path)
561                         sctp_assoc_update_retran_path(transport->asoc);
562                 transport->asoc->rtx_data_chunks +=
563                         transport->asoc->unack_data;
564                 break;
565         case SCTP_RTXR_FAST_RTX:
566                 SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
567                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
568                 q->fast_rtx = 1;
569                 break;
570         case SCTP_RTXR_PMTUD:
571                 SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
572                 break;
573         case SCTP_RTXR_T1_RTX:
574                 SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
575                 transport->asoc->init_retries++;
576                 break;
577         default:
578                 BUG();
579         }
580
581         sctp_retransmit_mark(q, transport, reason);
582
583         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
584          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
585          * following the procedures outlined in C1 - C5.
586          */
587         if (reason == SCTP_RTXR_T3_RTX)
588                 q->asoc->stream.si->generate_ftsn(q, q->asoc->ctsn_ack_point);
589
590         /* Flush the queues only on timeout, since fast_rtx is only
591          * triggered during sack processing and the queue
592          * will be flushed at the end.
593          */
594         if (reason != SCTP_RTXR_FAST_RTX)
595                 sctp_outq_flush(q, /* rtx_timeout */ 1, GFP_ATOMIC);
596 }
597
598 /*
599  * Transmit DATA chunks on the retransmit queue.  Upon return from
600  * __sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
601  * need to be transmitted by the caller.
602  * We assume that pkt->transport has already been set.
603  *
604  * The return value is a normal kernel error return value.
605  */
606 static int __sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
607                                  int rtx_timeout, int *start_timer, gfp_t gfp)
608 {
609         struct sctp_transport *transport = pkt->transport;
610         struct sctp_chunk *chunk, *chunk1;
611         struct list_head *lqueue;
612         enum sctp_xmit status;
613         int error = 0;
614         int timer = 0;
615         int done = 0;
616         int fast_rtx;
617
618         lqueue = &q->retransmit;
619         fast_rtx = q->fast_rtx;
620
621         /* This loop handles time-out retransmissions, fast retransmissions,
622          * and retransmissions due to opening of whindow.
623          *
624          * RFC 2960 6.3.3 Handle T3-rtx Expiration
625          *
626          * E3) Determine how many of the earliest (i.e., lowest TSN)
627          * outstanding DATA chunks for the address for which the
628          * T3-rtx has expired will fit into a single packet, subject
629          * to the MTU constraint for the path corresponding to the
630          * destination transport address to which the retransmission
631          * is being sent (this may be different from the address for
632          * which the timer expires [see Section 6.4]). Call this value
633          * K. Bundle and retransmit those K DATA chunks in a single
634          * packet to the destination endpoint.
635          *
636          * [Just to be painfully clear, if we are retransmitting
637          * because a timeout just happened, we should send only ONE
638          * packet of retransmitted data.]
639          *
640          * For fast retransmissions we also send only ONE packet.  However,
641          * if we are just flushing the queue due to open window, we'll
642          * try to send as much as possible.
643          */
644         list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
645                 /* If the chunk is abandoned, move it to abandoned list. */
646                 if (sctp_chunk_abandoned(chunk)) {
647                         list_del_init(&chunk->transmitted_list);
648                         sctp_insert_list(&q->abandoned,
649                                          &chunk->transmitted_list);
650                         continue;
651                 }
652
653                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
654                  * simple approach is just to move such TSNs out of the
655                  * way and into a 'transmitted' queue and skip to the
656                  * next chunk.
657                  */
658                 if (chunk->tsn_gap_acked) {
659                         list_move_tail(&chunk->transmitted_list,
660                                        &transport->transmitted);
661                         continue;
662                 }
663
664                 /* If we are doing fast retransmit, ignore non-fast_rtransmit
665                  * chunks
666                  */
667                 if (fast_rtx && !chunk->fast_retransmit)
668                         continue;
669
670 redo:
671                 /* Attempt to append this chunk to the packet. */
672                 status = sctp_packet_append_chunk(pkt, chunk);
673
674                 switch (status) {
675                 case SCTP_XMIT_PMTU_FULL:
676                         if (!pkt->has_data && !pkt->has_cookie_echo) {
677                                 /* If this packet did not contain DATA then
678                                  * retransmission did not happen, so do it
679                                  * again.  We'll ignore the error here since
680                                  * control chunks are already freed so there
681                                  * is nothing we can do.
682                                  */
683                                 sctp_packet_transmit(pkt, gfp);
684                                 goto redo;
685                         }
686
687                         /* Send this packet.  */
688                         error = sctp_packet_transmit(pkt, gfp);
689
690                         /* If we are retransmitting, we should only
691                          * send a single packet.
692                          * Otherwise, try appending this chunk again.
693                          */
694                         if (rtx_timeout || fast_rtx)
695                                 done = 1;
696                         else
697                                 goto redo;
698
699                         /* Bundle next chunk in the next round.  */
700                         break;
701
702                 case SCTP_XMIT_RWND_FULL:
703                         /* Send this packet. */
704                         error = sctp_packet_transmit(pkt, gfp);
705
706                         /* Stop sending DATA as there is no more room
707                          * at the receiver.
708                          */
709                         done = 1;
710                         break;
711
712                 case SCTP_XMIT_DELAY:
713                         /* Send this packet. */
714                         error = sctp_packet_transmit(pkt, gfp);
715
716                         /* Stop sending DATA because of nagle delay. */
717                         done = 1;
718                         break;
719
720                 default:
721                         /* The append was successful, so add this chunk to
722                          * the transmitted list.
723                          */
724                         list_move_tail(&chunk->transmitted_list,
725                                        &transport->transmitted);
726
727                         /* Mark the chunk as ineligible for fast retransmit
728                          * after it is retransmitted.
729                          */
730                         if (chunk->fast_retransmit == SCTP_NEED_FRTX)
731                                 chunk->fast_retransmit = SCTP_DONT_FRTX;
732
733                         q->asoc->stats.rtxchunks++;
734                         break;
735                 }
736
737                 /* Set the timer if there were no errors */
738                 if (!error && !timer)
739                         timer = 1;
740
741                 if (done)
742                         break;
743         }
744
745         /* If we are here due to a retransmit timeout or a fast
746          * retransmit and if there are any chunks left in the retransmit
747          * queue that could not fit in the PMTU sized packet, they need
748          * to be marked as ineligible for a subsequent fast retransmit.
749          */
750         if (rtx_timeout || fast_rtx) {
751                 list_for_each_entry(chunk1, lqueue, transmitted_list) {
752                         if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
753                                 chunk1->fast_retransmit = SCTP_DONT_FRTX;
754                 }
755         }
756
757         *start_timer = timer;
758
759         /* Clear fast retransmit hint */
760         if (fast_rtx)
761                 q->fast_rtx = 0;
762
763         return error;
764 }
765
766 /* Cork the outqueue so queued chunks are really queued. */
767 void sctp_outq_uncork(struct sctp_outq *q, gfp_t gfp)
768 {
769         if (q->cork)
770                 q->cork = 0;
771
772         sctp_outq_flush(q, 0, gfp);
773 }
774
775 static int sctp_packet_singleton(struct sctp_transport *transport,
776                                  struct sctp_chunk *chunk, gfp_t gfp)
777 {
778         const struct sctp_association *asoc = transport->asoc;
779         const __u16 sport = asoc->base.bind_addr.port;
780         const __u16 dport = asoc->peer.port;
781         const __u32 vtag = asoc->peer.i.init_tag;
782         struct sctp_packet singleton;
783
784         sctp_packet_init(&singleton, transport, sport, dport);
785         sctp_packet_config(&singleton, vtag, 0);
786         sctp_packet_append_chunk(&singleton, chunk);
787         return sctp_packet_transmit(&singleton, gfp);
788 }
789
790 /* Struct to hold the context during sctp outq flush */
791 struct sctp_flush_ctx {
792         struct sctp_outq *q;
793         /* Current transport being used. It's NOT the same as curr active one */
794         struct sctp_transport *transport;
795         /* These transports have chunks to send. */
796         struct list_head transport_list;
797         struct sctp_association *asoc;
798         /* Packet on the current transport above */
799         struct sctp_packet *packet;
800         gfp_t gfp;
801 };
802
803 /* transport: current transport */
804 static void sctp_outq_select_transport(struct sctp_flush_ctx *ctx,
805                                        struct sctp_chunk *chunk)
806 {
807         struct sctp_transport *new_transport = chunk->transport;
808
809         if (!new_transport) {
810                 if (!sctp_chunk_is_data(chunk)) {
811                         /* If we have a prior transport pointer, see if
812                          * the destination address of the chunk
813                          * matches the destination address of the
814                          * current transport.  If not a match, then
815                          * try to look up the transport with a given
816                          * destination address.  We do this because
817                          * after processing ASCONFs, we may have new
818                          * transports created.
819                          */
820                         if (ctx->transport && sctp_cmp_addr_exact(&chunk->dest,
821                                                         &ctx->transport->ipaddr))
822                                 new_transport = ctx->transport;
823                         else
824                                 new_transport = sctp_assoc_lookup_paddr(ctx->asoc,
825                                                                   &chunk->dest);
826                 }
827
828                 /* if we still don't have a new transport, then
829                  * use the current active path.
830                  */
831                 if (!new_transport)
832                         new_transport = ctx->asoc->peer.active_path;
833         } else {
834                 __u8 type;
835
836                 switch (new_transport->state) {
837                 case SCTP_INACTIVE:
838                 case SCTP_UNCONFIRMED:
839                 case SCTP_PF:
840                         /* If the chunk is Heartbeat or Heartbeat Ack,
841                          * send it to chunk->transport, even if it's
842                          * inactive.
843                          *
844                          * 3.3.6 Heartbeat Acknowledgement:
845                          * ...
846                          * A HEARTBEAT ACK is always sent to the source IP
847                          * address of the IP datagram containing the
848                          * HEARTBEAT chunk to which this ack is responding.
849                          * ...
850                          *
851                          * ASCONF_ACKs also must be sent to the source.
852                          */
853                         type = chunk->chunk_hdr->type;
854                         if (type != SCTP_CID_HEARTBEAT &&
855                             type != SCTP_CID_HEARTBEAT_ACK &&
856                             type != SCTP_CID_ASCONF_ACK)
857                                 new_transport = ctx->asoc->peer.active_path;
858                         break;
859                 default:
860                         break;
861                 }
862         }
863
864         /* Are we switching transports? Take care of transport locks. */
865         if (new_transport != ctx->transport) {
866                 ctx->transport = new_transport;
867                 ctx->packet = &ctx->transport->packet;
868
869                 if (list_empty(&ctx->transport->send_ready))
870                         list_add_tail(&ctx->transport->send_ready,
871                                       &ctx->transport_list);
872
873                 sctp_packet_config(ctx->packet,
874                                    ctx->asoc->peer.i.init_tag,
875                                    ctx->asoc->peer.ecn_capable);
876                 /* We've switched transports, so apply the
877                  * Burst limit to the new transport.
878                  */
879                 sctp_transport_burst_limited(ctx->transport);
880         }
881 }
882
883 static void sctp_outq_flush_ctrl(struct sctp_flush_ctx *ctx)
884 {
885         struct sctp_chunk *chunk, *tmp;
886         enum sctp_xmit status;
887         int one_packet, error;
888
889         list_for_each_entry_safe(chunk, tmp, &ctx->q->control_chunk_list, list) {
890                 one_packet = 0;
891
892                 /* RFC 5061, 5.3
893                  * F1) This means that until such time as the ASCONF
894                  * containing the add is acknowledged, the sender MUST
895                  * NOT use the new IP address as a source for ANY SCTP
896                  * packet except on carrying an ASCONF Chunk.
897                  */
898                 if (ctx->asoc->src_out_of_asoc_ok &&
899                     chunk->chunk_hdr->type != SCTP_CID_ASCONF)
900                         continue;
901
902                 list_del_init(&chunk->list);
903
904                 /* Pick the right transport to use. Should always be true for
905                  * the first chunk as we don't have a transport by then.
906                  */
907                 sctp_outq_select_transport(ctx, chunk);
908
909                 switch (chunk->chunk_hdr->type) {
910                 /* 6.10 Bundling
911                  *   ...
912                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
913                  *   COMPLETE with any other chunks.  [Send them immediately.]
914                  */
915                 case SCTP_CID_INIT:
916                 case SCTP_CID_INIT_ACK:
917                 case SCTP_CID_SHUTDOWN_COMPLETE:
918                         error = sctp_packet_singleton(ctx->transport, chunk,
919                                                       ctx->gfp);
920                         if (error < 0) {
921                                 ctx->asoc->base.sk->sk_err = -error;
922                                 return;
923                         }
924                         break;
925
926                 case SCTP_CID_ABORT:
927                         if (sctp_test_T_bit(chunk))
928                                 ctx->packet->vtag = ctx->asoc->c.my_vtag;
929                         /* fallthru */
930
931                 /* The following chunks are "response" chunks, i.e.
932                  * they are generated in response to something we
933                  * received.  If we are sending these, then we can
934                  * send only 1 packet containing these chunks.
935                  */
936                 case SCTP_CID_HEARTBEAT_ACK:
937                 case SCTP_CID_SHUTDOWN_ACK:
938                 case SCTP_CID_COOKIE_ACK:
939                 case SCTP_CID_COOKIE_ECHO:
940                 case SCTP_CID_ERROR:
941                 case SCTP_CID_ECN_CWR:
942                 case SCTP_CID_ASCONF_ACK:
943                         one_packet = 1;
944                         /* Fall through */
945
946                 case SCTP_CID_SACK:
947                 case SCTP_CID_HEARTBEAT:
948                 case SCTP_CID_SHUTDOWN:
949                 case SCTP_CID_ECN_ECNE:
950                 case SCTP_CID_ASCONF:
951                 case SCTP_CID_FWD_TSN:
952                 case SCTP_CID_I_FWD_TSN:
953                 case SCTP_CID_RECONF:
954                         status = sctp_packet_transmit_chunk(ctx->packet, chunk,
955                                                             one_packet, ctx->gfp);
956                         if (status != SCTP_XMIT_OK) {
957                                 /* put the chunk back */
958                                 list_add(&chunk->list, &ctx->q->control_chunk_list);
959                                 break;
960                         }
961
962                         ctx->asoc->stats.octrlchunks++;
963                         /* PR-SCTP C5) If a FORWARD TSN is sent, the
964                          * sender MUST assure that at least one T3-rtx
965                          * timer is running.
966                          */
967                         if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN ||
968                             chunk->chunk_hdr->type == SCTP_CID_I_FWD_TSN) {
969                                 sctp_transport_reset_t3_rtx(ctx->transport);
970                                 ctx->transport->last_time_sent = jiffies;
971                         }
972
973                         if (chunk == ctx->asoc->strreset_chunk)
974                                 sctp_transport_reset_reconf_timer(ctx->transport);
975
976                         break;
977
978                 default:
979                         /* We built a chunk with an illegal type! */
980                         BUG();
981                 }
982         }
983 }
984
985 /* Returns false if new data shouldn't be sent */
986 static bool sctp_outq_flush_rtx(struct sctp_flush_ctx *ctx,
987                                 int rtx_timeout)
988 {
989         int error, start_timer = 0;
990
991         if (ctx->asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
992                 return false;
993
994         if (ctx->transport != ctx->asoc->peer.retran_path) {
995                 /* Switch transports & prepare the packet.  */
996                 ctx->transport = ctx->asoc->peer.retran_path;
997                 ctx->packet = &ctx->transport->packet;
998
999                 if (list_empty(&ctx->transport->send_ready))
1000                         list_add_tail(&ctx->transport->send_ready,
1001                                       &ctx->transport_list);
1002
1003                 sctp_packet_config(ctx->packet, ctx->asoc->peer.i.init_tag,
1004                                    ctx->asoc->peer.ecn_capable);
1005         }
1006
1007         error = __sctp_outq_flush_rtx(ctx->q, ctx->packet, rtx_timeout,
1008                                       &start_timer, ctx->gfp);
1009         if (error < 0)
1010                 ctx->asoc->base.sk->sk_err = -error;
1011
1012         if (start_timer) {
1013                 sctp_transport_reset_t3_rtx(ctx->transport);
1014                 ctx->transport->last_time_sent = jiffies;
1015         }
1016
1017         /* This can happen on COOKIE-ECHO resend.  Only
1018          * one chunk can get bundled with a COOKIE-ECHO.
1019          */
1020         if (ctx->packet->has_cookie_echo)
1021                 return false;
1022
1023         /* Don't send new data if there is still data
1024          * waiting to retransmit.
1025          */
1026         if (!list_empty(&ctx->q->retransmit))
1027                 return false;
1028
1029         return true;
1030 }
1031
1032 static void sctp_outq_flush_data(struct sctp_flush_ctx *ctx,
1033                                  int rtx_timeout)
1034 {
1035         struct sctp_chunk *chunk;
1036         enum sctp_xmit status;
1037
1038         /* Is it OK to send data chunks?  */
1039         switch (ctx->asoc->state) {
1040         case SCTP_STATE_COOKIE_ECHOED:
1041                 /* Only allow bundling when this packet has a COOKIE-ECHO
1042                  * chunk.
1043                  */
1044                 if (!ctx->packet || !ctx->packet->has_cookie_echo)
1045                         return;
1046
1047                 /* fall through */
1048         case SCTP_STATE_ESTABLISHED:
1049         case SCTP_STATE_SHUTDOWN_PENDING:
1050         case SCTP_STATE_SHUTDOWN_RECEIVED:
1051                 break;
1052
1053         default:
1054                 /* Do nothing. */
1055                 return;
1056         }
1057
1058         /* RFC 2960 6.1  Transmission of DATA Chunks
1059          *
1060          * C) When the time comes for the sender to transmit,
1061          * before sending new DATA chunks, the sender MUST
1062          * first transmit any outstanding DATA chunks which
1063          * are marked for retransmission (limited by the
1064          * current cwnd).
1065          */
1066         if (!list_empty(&ctx->q->retransmit) &&
1067             !sctp_outq_flush_rtx(ctx, rtx_timeout))
1068                 return;
1069
1070         /* Apply Max.Burst limitation to the current transport in
1071          * case it will be used for new data.  We are going to
1072          * rest it before we return, but we want to apply the limit
1073          * to the currently queued data.
1074          */
1075         if (ctx->transport)
1076                 sctp_transport_burst_limited(ctx->transport);
1077
1078         /* Finally, transmit new packets.  */
1079         while ((chunk = sctp_outq_dequeue_data(ctx->q)) != NULL) {
1080                 __u32 sid = ntohs(chunk->subh.data_hdr->stream);
1081                 __u8 stream_state = SCTP_SO(&ctx->asoc->stream, sid)->state;
1082
1083                 /* Has this chunk expired? */
1084                 if (sctp_chunk_abandoned(chunk)) {
1085                         sctp_sched_dequeue_done(ctx->q, chunk);
1086                         sctp_chunk_fail(chunk, 0);
1087                         sctp_chunk_free(chunk);
1088                         continue;
1089                 }
1090
1091                 if (stream_state == SCTP_STREAM_CLOSED) {
1092                         sctp_outq_head_data(ctx->q, chunk);
1093                         break;
1094                 }
1095
1096                 sctp_outq_select_transport(ctx, chunk);
1097
1098                 pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p skb->users:%d\n",
1099                          __func__, ctx->q, chunk, chunk && chunk->chunk_hdr ?
1100                          sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
1101                          "illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
1102                          chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
1103                          refcount_read(&chunk->skb->users) : -1);
1104
1105                 /* Add the chunk to the packet.  */
1106                 status = sctp_packet_transmit_chunk(ctx->packet, chunk, 0,
1107                                                     ctx->gfp);
1108                 if (status != SCTP_XMIT_OK) {
1109                         /* We could not append this chunk, so put
1110                          * the chunk back on the output queue.
1111                          */
1112                         pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
1113                                  __func__, ntohl(chunk->subh.data_hdr->tsn),
1114                                  status);
1115
1116                         sctp_outq_head_data(ctx->q, chunk);
1117                         break;
1118                 }
1119
1120                 /* The sender is in the SHUTDOWN-PENDING state,
1121                  * The sender MAY set the I-bit in the DATA
1122                  * chunk header.
1123                  */
1124                 if (ctx->asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1125                         chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1126                 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
1127                         ctx->asoc->stats.ouodchunks++;
1128                 else
1129                         ctx->asoc->stats.oodchunks++;
1130
1131                 /* Only now it's safe to consider this
1132                  * chunk as sent, sched-wise.
1133                  */
1134                 sctp_sched_dequeue_done(ctx->q, chunk);
1135
1136                 list_add_tail(&chunk->transmitted_list,
1137                               &ctx->transport->transmitted);
1138
1139                 sctp_transport_reset_t3_rtx(ctx->transport);
1140                 ctx->transport->last_time_sent = jiffies;
1141
1142                 /* Only let one DATA chunk get bundled with a
1143                  * COOKIE-ECHO chunk.
1144                  */
1145                 if (ctx->packet->has_cookie_echo)
1146                         break;
1147         }
1148 }
1149
1150 static void sctp_outq_flush_transports(struct sctp_flush_ctx *ctx)
1151 {
1152         struct list_head *ltransport;
1153         struct sctp_packet *packet;
1154         struct sctp_transport *t;
1155         int error = 0;
1156
1157         while ((ltransport = sctp_list_dequeue(&ctx->transport_list)) != NULL) {
1158                 t = list_entry(ltransport, struct sctp_transport, send_ready);
1159                 packet = &t->packet;
1160                 if (!sctp_packet_empty(packet)) {
1161                         error = sctp_packet_transmit(packet, ctx->gfp);
1162                         if (error < 0)
1163                                 ctx->q->asoc->base.sk->sk_err = -error;
1164                 }
1165
1166                 /* Clear the burst limited state, if any */
1167                 sctp_transport_burst_reset(t);
1168         }
1169 }
1170
1171 /* Try to flush an outqueue.
1172  *
1173  * Description: Send everything in q which we legally can, subject to
1174  * congestion limitations.
1175  * * Note: This function can be called from multiple contexts so appropriate
1176  * locking concerns must be made.  Today we use the sock lock to protect
1177  * this function.
1178  */
1179
1180 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
1181 {
1182         struct sctp_flush_ctx ctx = {
1183                 .q = q,
1184                 .transport = NULL,
1185                 .transport_list = LIST_HEAD_INIT(ctx.transport_list),
1186                 .asoc = q->asoc,
1187                 .packet = NULL,
1188                 .gfp = gfp,
1189         };
1190
1191         /* 6.10 Bundling
1192          *   ...
1193          *   When bundling control chunks with DATA chunks, an
1194          *   endpoint MUST place control chunks first in the outbound
1195          *   SCTP packet.  The transmitter MUST transmit DATA chunks
1196          *   within a SCTP packet in increasing order of TSN.
1197          *   ...
1198          */
1199
1200         sctp_outq_flush_ctrl(&ctx);
1201
1202         if (q->asoc->src_out_of_asoc_ok)
1203                 goto sctp_flush_out;
1204
1205         sctp_outq_flush_data(&ctx, rtx_timeout);
1206
1207 sctp_flush_out:
1208
1209         sctp_outq_flush_transports(&ctx);
1210 }
1211
1212 /* Update unack_data based on the incoming SACK chunk */
1213 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1214                                         struct sctp_sackhdr *sack)
1215 {
1216         union sctp_sack_variable *frags;
1217         __u16 unack_data;
1218         int i;
1219
1220         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1221
1222         frags = sack->variable;
1223         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1224                 unack_data -= ((ntohs(frags[i].gab.end) -
1225                                 ntohs(frags[i].gab.start) + 1));
1226         }
1227
1228         assoc->unack_data = unack_data;
1229 }
1230
1231 /* This is where we REALLY process a SACK.
1232  *
1233  * Process the SACK against the outqueue.  Mostly, this just frees
1234  * things off the transmitted queue.
1235  */
1236 int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1237 {
1238         struct sctp_association *asoc = q->asoc;
1239         struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1240         struct sctp_transport *transport;
1241         struct sctp_chunk *tchunk = NULL;
1242         struct list_head *lchunk, *transport_list, *temp;
1243         union sctp_sack_variable *frags = sack->variable;
1244         __u32 sack_ctsn, ctsn, tsn;
1245         __u32 highest_tsn, highest_new_tsn;
1246         __u32 sack_a_rwnd;
1247         unsigned int outstanding;
1248         struct sctp_transport *primary = asoc->peer.primary_path;
1249         int count_of_newacks = 0;
1250         int gap_ack_blocks;
1251         u8 accum_moved = 0;
1252
1253         /* Grab the association's destination address list. */
1254         transport_list = &asoc->peer.transport_addr_list;
1255
1256         sack_ctsn = ntohl(sack->cum_tsn_ack);
1257         gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1258         asoc->stats.gapcnt += gap_ack_blocks;
1259         /*
1260          * SFR-CACC algorithm:
1261          * On receipt of a SACK the sender SHOULD execute the
1262          * following statements.
1263          *
1264          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1265          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1266          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1267          * all destinations.
1268          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1269          * is set the receiver of the SACK MUST take the following actions:
1270          *
1271          * A) Initialize the cacc_saw_newack to 0 for all destination
1272          * addresses.
1273          *
1274          * Only bother if changeover_active is set. Otherwise, this is
1275          * totally suboptimal to do on every SACK.
1276          */
1277         if (primary->cacc.changeover_active) {
1278                 u8 clear_cycling = 0;
1279
1280                 if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1281                         primary->cacc.changeover_active = 0;
1282                         clear_cycling = 1;
1283                 }
1284
1285                 if (clear_cycling || gap_ack_blocks) {
1286                         list_for_each_entry(transport, transport_list,
1287                                         transports) {
1288                                 if (clear_cycling)
1289                                         transport->cacc.cycling_changeover = 0;
1290                                 if (gap_ack_blocks)
1291                                         transport->cacc.cacc_saw_newack = 0;
1292                         }
1293                 }
1294         }
1295
1296         /* Get the highest TSN in the sack. */
1297         highest_tsn = sack_ctsn;
1298         if (gap_ack_blocks)
1299                 highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1300
1301         if (TSN_lt(asoc->highest_sacked, highest_tsn))
1302                 asoc->highest_sacked = highest_tsn;
1303
1304         highest_new_tsn = sack_ctsn;
1305
1306         /* Run through the retransmit queue.  Credit bytes received
1307          * and free those chunks that we can.
1308          */
1309         sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1310
1311         /* Run through the transmitted queue.
1312          * Credit bytes received and free those chunks which we can.
1313          *
1314          * This is a MASSIVE candidate for optimization.
1315          */
1316         list_for_each_entry(transport, transport_list, transports) {
1317                 sctp_check_transmitted(q, &transport->transmitted,
1318                                        transport, &chunk->source, sack,
1319                                        &highest_new_tsn);
1320                 /*
1321                  * SFR-CACC algorithm:
1322                  * C) Let count_of_newacks be the number of
1323                  * destinations for which cacc_saw_newack is set.
1324                  */
1325                 if (transport->cacc.cacc_saw_newack)
1326                         count_of_newacks++;
1327         }
1328
1329         /* Move the Cumulative TSN Ack Point if appropriate.  */
1330         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1331                 asoc->ctsn_ack_point = sack_ctsn;
1332                 accum_moved = 1;
1333         }
1334
1335         if (gap_ack_blocks) {
1336
1337                 if (asoc->fast_recovery && accum_moved)
1338                         highest_new_tsn = highest_tsn;
1339
1340                 list_for_each_entry(transport, transport_list, transports)
1341                         sctp_mark_missing(q, &transport->transmitted, transport,
1342                                           highest_new_tsn, count_of_newacks);
1343         }
1344
1345         /* Update unack_data field in the assoc. */
1346         sctp_sack_update_unack_data(asoc, sack);
1347
1348         ctsn = asoc->ctsn_ack_point;
1349
1350         /* Throw away stuff rotting on the sack queue.  */
1351         list_for_each_safe(lchunk, temp, &q->sacked) {
1352                 tchunk = list_entry(lchunk, struct sctp_chunk,
1353                                     transmitted_list);
1354                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1355                 if (TSN_lte(tsn, ctsn)) {
1356                         list_del_init(&tchunk->transmitted_list);
1357                         if (asoc->peer.prsctp_capable &&
1358                             SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
1359                                 asoc->sent_cnt_removable--;
1360                         sctp_chunk_free(tchunk);
1361                 }
1362         }
1363
1364         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1365          *     number of bytes still outstanding after processing the
1366          *     Cumulative TSN Ack and the Gap Ack Blocks.
1367          */
1368
1369         sack_a_rwnd = ntohl(sack->a_rwnd);
1370         asoc->peer.zero_window_announced = !sack_a_rwnd;
1371         outstanding = q->outstanding_bytes;
1372
1373         if (outstanding < sack_a_rwnd)
1374                 sack_a_rwnd -= outstanding;
1375         else
1376                 sack_a_rwnd = 0;
1377
1378         asoc->peer.rwnd = sack_a_rwnd;
1379
1380         asoc->stream.si->generate_ftsn(q, sack_ctsn);
1381
1382         pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
1383         pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
1384                  "advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
1385                  asoc->adv_peer_ack_point);
1386
1387         return sctp_outq_is_empty(q);
1388 }
1389
1390 /* Is the outqueue empty?
1391  * The queue is empty when we have not pending data, no in-flight data
1392  * and nothing pending retransmissions.
1393  */
1394 int sctp_outq_is_empty(const struct sctp_outq *q)
1395 {
1396         return q->out_qlen == 0 && q->outstanding_bytes == 0 &&
1397                list_empty(&q->retransmit);
1398 }
1399
1400 /********************************************************************
1401  * 2nd Level Abstractions
1402  ********************************************************************/
1403
1404 /* Go through a transport's transmitted list or the association's retransmit
1405  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1406  * The retransmit list will not have an associated transport.
1407  *
1408  * I added coherent debug information output.   --xguo
1409  *
1410  * Instead of printing 'sacked' or 'kept' for each TSN on the
1411  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1412  * KEPT TSN6-TSN7, etc.
1413  */
1414 static void sctp_check_transmitted(struct sctp_outq *q,
1415                                    struct list_head *transmitted_queue,
1416                                    struct sctp_transport *transport,
1417                                    union sctp_addr *saddr,
1418                                    struct sctp_sackhdr *sack,
1419                                    __u32 *highest_new_tsn_in_sack)
1420 {
1421         struct list_head *lchunk;
1422         struct sctp_chunk *tchunk;
1423         struct list_head tlist;
1424         __u32 tsn;
1425         __u32 sack_ctsn;
1426         __u32 rtt;
1427         __u8 restart_timer = 0;
1428         int bytes_acked = 0;
1429         int migrate_bytes = 0;
1430         bool forward_progress = false;
1431
1432         sack_ctsn = ntohl(sack->cum_tsn_ack);
1433
1434         INIT_LIST_HEAD(&tlist);
1435
1436         /* The while loop will skip empty transmitted queues. */
1437         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1438                 tchunk = list_entry(lchunk, struct sctp_chunk,
1439                                     transmitted_list);
1440
1441                 if (sctp_chunk_abandoned(tchunk)) {
1442                         /* Move the chunk to abandoned list. */
1443                         sctp_insert_list(&q->abandoned, lchunk);
1444
1445                         /* If this chunk has not been acked, stop
1446                          * considering it as 'outstanding'.
1447                          */
1448                         if (transmitted_queue != &q->retransmit &&
1449                             !tchunk->tsn_gap_acked) {
1450                                 if (tchunk->transport)
1451                                         tchunk->transport->flight_size -=
1452                                                         sctp_data_size(tchunk);
1453                                 q->outstanding_bytes -= sctp_data_size(tchunk);
1454                         }
1455                         continue;
1456                 }
1457
1458                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1459                 if (sctp_acked(sack, tsn)) {
1460                         /* If this queue is the retransmit queue, the
1461                          * retransmit timer has already reclaimed
1462                          * the outstanding bytes for this chunk, so only
1463                          * count bytes associated with a transport.
1464                          */
1465                         if (transport && !tchunk->tsn_gap_acked) {
1466                                 /* If this chunk is being used for RTT
1467                                  * measurement, calculate the RTT and update
1468                                  * the RTO using this value.
1469                                  *
1470                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1471                                  * MUST NOT be made using packets that were
1472                                  * retransmitted (and thus for which it is
1473                                  * ambiguous whether the reply was for the
1474                                  * first instance of the packet or a later
1475                                  * instance).
1476                                  */
1477                                 if (!sctp_chunk_retransmitted(tchunk) &&
1478                                     tchunk->rtt_in_progress) {
1479                                         tchunk->rtt_in_progress = 0;
1480                                         rtt = jiffies - tchunk->sent_at;
1481                                         sctp_transport_update_rto(transport,
1482                                                                   rtt);
1483                                 }
1484
1485                                 if (TSN_lte(tsn, sack_ctsn)) {
1486                                         /*
1487                                          * SFR-CACC algorithm:
1488                                          * 2) If the SACK contains gap acks
1489                                          * and the flag CHANGEOVER_ACTIVE is
1490                                          * set the receiver of the SACK MUST
1491                                          * take the following action:
1492                                          *
1493                                          * B) For each TSN t being acked that
1494                                          * has not been acked in any SACK so
1495                                          * far, set cacc_saw_newack to 1 for
1496                                          * the destination that the TSN was
1497                                          * sent to.
1498                                          */
1499                                         if (sack->num_gap_ack_blocks &&
1500                                             q->asoc->peer.primary_path->cacc.
1501                                             changeover_active)
1502                                                 transport->cacc.cacc_saw_newack
1503                                                         = 1;
1504                                 }
1505                         }
1506
1507                         /* If the chunk hasn't been marked as ACKED,
1508                          * mark it and account bytes_acked if the
1509                          * chunk had a valid transport (it will not
1510                          * have a transport if ASCONF had deleted it
1511                          * while DATA was outstanding).
1512                          */
1513                         if (!tchunk->tsn_gap_acked) {
1514                                 tchunk->tsn_gap_acked = 1;
1515                                 if (TSN_lt(*highest_new_tsn_in_sack, tsn))
1516                                         *highest_new_tsn_in_sack = tsn;
1517                                 bytes_acked += sctp_data_size(tchunk);
1518                                 if (!tchunk->transport)
1519                                         migrate_bytes += sctp_data_size(tchunk);
1520                                 forward_progress = true;
1521                         }
1522
1523                         if (TSN_lte(tsn, sack_ctsn)) {
1524                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1525                                  *
1526                                  * R3) Whenever a SACK is received
1527                                  * that acknowledges the DATA chunk
1528                                  * with the earliest outstanding TSN
1529                                  * for that address, restart T3-rtx
1530                                  * timer for that address with its
1531                                  * current RTO.
1532                                  */
1533                                 restart_timer = 1;
1534                                 forward_progress = true;
1535
1536                                 list_add_tail(&tchunk->transmitted_list,
1537                                               &q->sacked);
1538                         } else {
1539                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1540                                  * M2) Each time a SACK arrives reporting
1541                                  * 'Stray DATA chunk(s)' record the highest TSN
1542                                  * reported as newly acknowledged, call this
1543                                  * value 'HighestTSNinSack'. A newly
1544                                  * acknowledged DATA chunk is one not
1545                                  * previously acknowledged in a SACK.
1546                                  *
1547                                  * When the SCTP sender of data receives a SACK
1548                                  * chunk that acknowledges, for the first time,
1549                                  * the receipt of a DATA chunk, all the still
1550                                  * unacknowledged DATA chunks whose TSN is
1551                                  * older than that newly acknowledged DATA
1552                                  * chunk, are qualified as 'Stray DATA chunks'.
1553                                  */
1554                                 list_add_tail(lchunk, &tlist);
1555                         }
1556                 } else {
1557                         if (tchunk->tsn_gap_acked) {
1558                                 pr_debug("%s: receiver reneged on data TSN:0x%x\n",
1559                                          __func__, tsn);
1560
1561                                 tchunk->tsn_gap_acked = 0;
1562
1563                                 if (tchunk->transport)
1564                                         bytes_acked -= sctp_data_size(tchunk);
1565
1566                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1567                                  *
1568                                  * R4) Whenever a SACK is received missing a
1569                                  * TSN that was previously acknowledged via a
1570                                  * Gap Ack Block, start T3-rtx for the
1571                                  * destination address to which the DATA
1572                                  * chunk was originally
1573                                  * transmitted if it is not already running.
1574                                  */
1575                                 restart_timer = 1;
1576                         }
1577
1578                         list_add_tail(lchunk, &tlist);
1579                 }
1580         }
1581
1582         if (transport) {
1583                 if (bytes_acked) {
1584                         struct sctp_association *asoc = transport->asoc;
1585
1586                         /* We may have counted DATA that was migrated
1587                          * to this transport due to DEL-IP operation.
1588                          * Subtract those bytes, since the were never
1589                          * send on this transport and shouldn't be
1590                          * credited to this transport.
1591                          */
1592                         bytes_acked -= migrate_bytes;
1593
1594                         /* 8.2. When an outstanding TSN is acknowledged,
1595                          * the endpoint shall clear the error counter of
1596                          * the destination transport address to which the
1597                          * DATA chunk was last sent.
1598                          * The association's overall error counter is
1599                          * also cleared.
1600                          */
1601                         transport->error_count = 0;
1602                         transport->asoc->overall_error_count = 0;
1603                         forward_progress = true;
1604
1605                         /*
1606                          * While in SHUTDOWN PENDING, we may have started
1607                          * the T5 shutdown guard timer after reaching the
1608                          * retransmission limit. Stop that timer as soon
1609                          * as the receiver acknowledged any data.
1610                          */
1611                         if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1612                             del_timer(&asoc->timers
1613                                 [SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1614                                         sctp_association_put(asoc);
1615
1616                         /* Mark the destination transport address as
1617                          * active if it is not so marked.
1618                          */
1619                         if ((transport->state == SCTP_INACTIVE ||
1620                              transport->state == SCTP_UNCONFIRMED) &&
1621                             sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1622                                 sctp_assoc_control_transport(
1623                                         transport->asoc,
1624                                         transport,
1625                                         SCTP_TRANSPORT_UP,
1626                                         SCTP_RECEIVED_SACK);
1627                         }
1628
1629                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1630                                                   bytes_acked);
1631
1632                         transport->flight_size -= bytes_acked;
1633                         if (transport->flight_size == 0)
1634                                 transport->partial_bytes_acked = 0;
1635                         q->outstanding_bytes -= bytes_acked + migrate_bytes;
1636                 } else {
1637                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1638                          * When a sender is doing zero window probing, it
1639                          * should not timeout the association if it continues
1640                          * to receive new packets from the receiver. The
1641                          * reason is that the receiver MAY keep its window
1642                          * closed for an indefinite time.
1643                          * A sender is doing zero window probing when the
1644                          * receiver's advertised window is zero, and there is
1645                          * only one data chunk in flight to the receiver.
1646                          *
1647                          * Allow the association to timeout while in SHUTDOWN
1648                          * PENDING or SHUTDOWN RECEIVED in case the receiver
1649                          * stays in zero window mode forever.
1650                          */
1651                         if (!q->asoc->peer.rwnd &&
1652                             !list_empty(&tlist) &&
1653                             (sack_ctsn+2 == q->asoc->next_tsn) &&
1654                             q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1655                                 pr_debug("%s: sack received for zero window "
1656                                          "probe:%u\n", __func__, sack_ctsn);
1657
1658                                 q->asoc->overall_error_count = 0;
1659                                 transport->error_count = 0;
1660                         }
1661                 }
1662
1663                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1664                  *
1665                  * R2) Whenever all outstanding data sent to an address have
1666                  * been acknowledged, turn off the T3-rtx timer of that
1667                  * address.
1668                  */
1669                 if (!transport->flight_size) {
1670                         if (del_timer(&transport->T3_rtx_timer))
1671                                 sctp_transport_put(transport);
1672                 } else if (restart_timer) {
1673                         if (!mod_timer(&transport->T3_rtx_timer,
1674                                        jiffies + transport->rto))
1675                                 sctp_transport_hold(transport);
1676                 }
1677
1678                 if (forward_progress) {
1679                         if (transport->dst)
1680                                 sctp_transport_dst_confirm(transport);
1681                 }
1682         }
1683
1684         list_splice(&tlist, transmitted_queue);
1685 }
1686
1687 /* Mark chunks as missing and consequently may get retransmitted. */
1688 static void sctp_mark_missing(struct sctp_outq *q,
1689                               struct list_head *transmitted_queue,
1690                               struct sctp_transport *transport,
1691                               __u32 highest_new_tsn_in_sack,
1692                               int count_of_newacks)
1693 {
1694         struct sctp_chunk *chunk;
1695         __u32 tsn;
1696         char do_fast_retransmit = 0;
1697         struct sctp_association *asoc = q->asoc;
1698         struct sctp_transport *primary = asoc->peer.primary_path;
1699
1700         list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1701
1702                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1703
1704                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1705                  * 'Unacknowledged TSN's', if the TSN number of an
1706                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1707                  * value, increment the 'TSN.Missing.Report' count on that
1708                  * chunk if it has NOT been fast retransmitted or marked for
1709                  * fast retransmit already.
1710                  */
1711                 if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1712                     !chunk->tsn_gap_acked &&
1713                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1714
1715                         /* SFR-CACC may require us to skip marking
1716                          * this chunk as missing.
1717                          */
1718                         if (!transport || !sctp_cacc_skip(primary,
1719                                                 chunk->transport,
1720                                                 count_of_newacks, tsn)) {
1721                                 chunk->tsn_missing_report++;
1722
1723                                 pr_debug("%s: tsn:0x%x missing counter:%d\n",
1724                                          __func__, tsn, chunk->tsn_missing_report);
1725                         }
1726                 }
1727                 /*
1728                  * M4) If any DATA chunk is found to have a
1729                  * 'TSN.Missing.Report'
1730                  * value larger than or equal to 3, mark that chunk for
1731                  * retransmission and start the fast retransmit procedure.
1732                  */
1733
1734                 if (chunk->tsn_missing_report >= 3) {
1735                         chunk->fast_retransmit = SCTP_NEED_FRTX;
1736                         do_fast_retransmit = 1;
1737                 }
1738         }
1739
1740         if (transport) {
1741                 if (do_fast_retransmit)
1742                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1743
1744                 pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
1745                          "flight_size:%d, pba:%d\n",  __func__, transport,
1746                          transport->cwnd, transport->ssthresh,
1747                          transport->flight_size, transport->partial_bytes_acked);
1748         }
1749 }
1750
1751 /* Is the given TSN acked by this packet?  */
1752 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1753 {
1754         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1755         union sctp_sack_variable *frags;
1756         __u16 tsn_offset, blocks;
1757         int i;
1758
1759         if (TSN_lte(tsn, ctsn))
1760                 goto pass;
1761
1762         /* 3.3.4 Selective Acknowledgment (SACK) (3):
1763          *
1764          * Gap Ack Blocks:
1765          *  These fields contain the Gap Ack Blocks. They are repeated
1766          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1767          *  defined in the Number of Gap Ack Blocks field. All DATA
1768          *  chunks with TSNs greater than or equal to (Cumulative TSN
1769          *  Ack + Gap Ack Block Start) and less than or equal to
1770          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1771          *  Block are assumed to have been received correctly.
1772          */
1773
1774         frags = sack->variable;
1775         blocks = ntohs(sack->num_gap_ack_blocks);
1776         tsn_offset = tsn - ctsn;
1777         for (i = 0; i < blocks; ++i) {
1778                 if (tsn_offset >= ntohs(frags[i].gab.start) &&
1779                     tsn_offset <= ntohs(frags[i].gab.end))
1780                         goto pass;
1781         }
1782
1783         return 0;
1784 pass:
1785         return 1;
1786 }
1787
1788 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1789                                     int nskips, __be16 stream)
1790 {
1791         int i;
1792
1793         for (i = 0; i < nskips; i++) {
1794                 if (skiplist[i].stream == stream)
1795                         return i;
1796         }
1797         return i;
1798 }
1799
1800 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1801 void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1802 {
1803         struct sctp_association *asoc = q->asoc;
1804         struct sctp_chunk *ftsn_chunk = NULL;
1805         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1806         int nskips = 0;
1807         int skip_pos = 0;
1808         __u32 tsn;
1809         struct sctp_chunk *chunk;
1810         struct list_head *lchunk, *temp;
1811
1812         if (!asoc->peer.prsctp_capable)
1813                 return;
1814
1815         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1816          * received SACK.
1817          *
1818          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1819          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1820          */
1821         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1822                 asoc->adv_peer_ack_point = ctsn;
1823
1824         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1825          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1826          * the chunk next in the out-queue space is marked as "abandoned" as
1827          * shown in the following example:
1828          *
1829          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1830          * and the Advanced.Peer.Ack.Point is updated to this value:
1831          *
1832          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1833          *   normal SACK processing           local advancement
1834          *                ...                           ...
1835          *   Adv.Ack.Pt-> 102 acked                     102 acked
1836          *                103 abandoned                 103 abandoned
1837          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1838          *                105                           105
1839          *                106 acked                     106 acked
1840          *                ...                           ...
1841          *
1842          * In this example, the data sender successfully advanced the
1843          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1844          */
1845         list_for_each_safe(lchunk, temp, &q->abandoned) {
1846                 chunk = list_entry(lchunk, struct sctp_chunk,
1847                                         transmitted_list);
1848                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1849
1850                 /* Remove any chunks in the abandoned queue that are acked by
1851                  * the ctsn.
1852                  */
1853                 if (TSN_lte(tsn, ctsn)) {
1854                         list_del_init(lchunk);
1855                         sctp_chunk_free(chunk);
1856                 } else {
1857                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1858                                 asoc->adv_peer_ack_point = tsn;
1859                                 if (chunk->chunk_hdr->flags &
1860                                          SCTP_DATA_UNORDERED)
1861                                         continue;
1862                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1863                                                 nskips,
1864                                                 chunk->subh.data_hdr->stream);
1865                                 ftsn_skip_arr[skip_pos].stream =
1866                                         chunk->subh.data_hdr->stream;
1867                                 ftsn_skip_arr[skip_pos].ssn =
1868                                          chunk->subh.data_hdr->ssn;
1869                                 if (skip_pos == nskips)
1870                                         nskips++;
1871                                 if (nskips == 10)
1872                                         break;
1873                         } else
1874                                 break;
1875                 }
1876         }
1877
1878         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1879          * is greater than the Cumulative TSN ACK carried in the received
1880          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1881          * chunk containing the latest value of the
1882          * "Advanced.Peer.Ack.Point".
1883          *
1884          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1885          * list each stream and sequence number in the forwarded TSN. This
1886          * information will enable the receiver to easily find any
1887          * stranded TSN's waiting on stream reorder queues. Each stream
1888          * SHOULD only be reported once; this means that if multiple
1889          * abandoned messages occur in the same stream then only the
1890          * highest abandoned stream sequence number is reported. If the
1891          * total size of the FORWARD TSN does NOT fit in a single MTU then
1892          * the sender of the FORWARD TSN SHOULD lower the
1893          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1894          * single MTU.
1895          */
1896         if (asoc->adv_peer_ack_point > ctsn)
1897                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1898                                               nskips, &ftsn_skip_arr[0]);
1899
1900         if (ftsn_chunk) {
1901                 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1902                 SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_OUTCTRLCHUNKS);
1903         }
1904 }