sctp: move chunk from retransmit queue to abandoned list
[linux-3.10.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, write to
26  * the Free Software Foundation, 59 Temple Place - Suite 330,
27  * Boston, MA 02111-1307, USA.
28  *
29  * Please send any bug reports or fixes you make to the
30  * email address(es):
31  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
32  *
33  * Or submit a bug report through the following website:
34  *    http://www.sf.net/projects/lksctp
35  *
36  * Written or modified by:
37  *    La Monte H.P. Yarroll <piggy@acm.org>
38  *    Karl Knutson          <karl@athena.chicago.il.us>
39  *    Perry Melange         <pmelange@null.cc.uic.edu>
40  *    Xingang Guo           <xingang.guo@intel.com>
41  *    Hui Huang             <hui.huang@nokia.com>
42  *    Sridhar Samudrala     <sri@us.ibm.com>
43  *    Jon Grimm             <jgrimm@us.ibm.com>
44  *
45  * Any bugs reported given to us we will try to fix... any fixes shared will
46  * be incorporated into the next SCTP release.
47  */
48
49 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
50
51 #include <linux/types.h>
52 #include <linux/list.h>   /* For struct list_head */
53 #include <linux/socket.h>
54 #include <linux/ip.h>
55 #include <linux/slab.h>
56 #include <net/sock.h>     /* For skb_set_owner_w */
57
58 #include <net/sctp/sctp.h>
59 #include <net/sctp/sm.h>
60
61 /* Declare internal functions here.  */
62 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
63 static void sctp_check_transmitted(struct sctp_outq *q,
64                                    struct list_head *transmitted_queue,
65                                    struct sctp_transport *transport,
66                                    struct sctp_sackhdr *sack,
67                                    __u32 *highest_new_tsn);
68
69 static void sctp_mark_missing(struct sctp_outq *q,
70                               struct list_head *transmitted_queue,
71                               struct sctp_transport *transport,
72                               __u32 highest_new_tsn,
73                               int count_of_newacks);
74
75 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);
76
77 static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout);
78
79 /* Add data to the front of the queue. */
80 static inline void sctp_outq_head_data(struct sctp_outq *q,
81                                         struct sctp_chunk *ch)
82 {
83         list_add(&ch->list, &q->out_chunk_list);
84         q->out_qlen += ch->skb->len;
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         struct sctp_chunk *ch = NULL;
91
92         if (!list_empty(&q->out_chunk_list)) {
93                 struct list_head *entry = q->out_chunk_list.next;
94
95                 ch = list_entry(entry, struct sctp_chunk, list);
96                 list_del_init(entry);
97                 q->out_qlen -= ch->skb->len;
98         }
99         return ch;
100 }
101 /* Add data chunk to the end of the queue. */
102 static inline void sctp_outq_tail_data(struct sctp_outq *q,
103                                        struct sctp_chunk *ch)
104 {
105         list_add_tail(&ch->list, &q->out_chunk_list);
106         q->out_qlen += ch->skb->len;
107 }
108
109 /*
110  * SFR-CACC algorithm:
111  * D) If count_of_newacks is greater than or equal to 2
112  * and t was not sent to the current primary then the
113  * sender MUST NOT increment missing report count for t.
114  */
115 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
116                                        struct sctp_transport *transport,
117                                        int count_of_newacks)
118 {
119         if (count_of_newacks >=2 && transport != primary)
120                 return 1;
121         return 0;
122 }
123
124 /*
125  * SFR-CACC algorithm:
126  * F) If count_of_newacks is less than 2, let d be the
127  * destination to which t was sent. If cacc_saw_newack
128  * is 0 for destination d, then the sender MUST NOT
129  * increment missing report count for t.
130  */
131 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
132                                        int count_of_newacks)
133 {
134         if (count_of_newacks < 2 &&
135                         (transport && !transport->cacc.cacc_saw_newack))
136                 return 1;
137         return 0;
138 }
139
140 /*
141  * SFR-CACC algorithm:
142  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
143  * execute steps C, D, F.
144  *
145  * C has been implemented in sctp_outq_sack
146  */
147 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
148                                      struct sctp_transport *transport,
149                                      int count_of_newacks)
150 {
151         if (!primary->cacc.cycling_changeover) {
152                 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
153                         return 1;
154                 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
155                         return 1;
156                 return 0;
157         }
158         return 0;
159 }
160
161 /*
162  * SFR-CACC algorithm:
163  * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
164  * than next_tsn_at_change of the current primary, then
165  * the sender MUST NOT increment missing report count
166  * for t.
167  */
168 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
169 {
170         if (primary->cacc.cycling_changeover &&
171             TSN_lt(tsn, primary->cacc.next_tsn_at_change))
172                 return 1;
173         return 0;
174 }
175
176 /*
177  * SFR-CACC algorithm:
178  * 3) If the missing report count for TSN t is to be
179  * incremented according to [RFC2960] and
180  * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
181  * then the sender MUST further execute steps 3.1 and
182  * 3.2 to determine if the missing report count for
183  * TSN t SHOULD NOT be incremented.
184  *
185  * 3.3) If 3.1 and 3.2 do not dictate that the missing
186  * report count for t should not be incremented, then
187  * the sender SHOULD increment missing report count for
188  * t (according to [RFC2960] and [SCTP_STEWART_2002]).
189  */
190 static inline int sctp_cacc_skip(struct sctp_transport *primary,
191                                  struct sctp_transport *transport,
192                                  int count_of_newacks,
193                                  __u32 tsn)
194 {
195         if (primary->cacc.changeover_active &&
196             (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
197              sctp_cacc_skip_3_2(primary, tsn)))
198                 return 1;
199         return 0;
200 }
201
202 /* Initialize an existing sctp_outq.  This does the boring stuff.
203  * You still need to define handlers if you really want to DO
204  * something with this structure...
205  */
206 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
207 {
208         q->asoc = asoc;
209         INIT_LIST_HEAD(&q->out_chunk_list);
210         INIT_LIST_HEAD(&q->control_chunk_list);
211         INIT_LIST_HEAD(&q->retransmit);
212         INIT_LIST_HEAD(&q->sacked);
213         INIT_LIST_HEAD(&q->abandoned);
214
215         q->fast_rtx = 0;
216         q->outstanding_bytes = 0;
217         q->empty = 1;
218         q->cork  = 0;
219
220         q->malloced = 0;
221         q->out_qlen = 0;
222 }
223
224 /* Free the outqueue structure and any related pending chunks.
225  */
226 void sctp_outq_teardown(struct sctp_outq *q)
227 {
228         struct sctp_transport *transport;
229         struct list_head *lchunk, *temp;
230         struct sctp_chunk *chunk, *tmp;
231
232         /* Throw away unacknowledged chunks. */
233         list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
234                         transports) {
235                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
236                         chunk = list_entry(lchunk, struct sctp_chunk,
237                                            transmitted_list);
238                         /* Mark as part of a failed message. */
239                         sctp_chunk_fail(chunk, q->error);
240                         sctp_chunk_free(chunk);
241                 }
242         }
243
244         /* Throw away chunks that have been gap ACKed.  */
245         list_for_each_safe(lchunk, temp, &q->sacked) {
246                 list_del_init(lchunk);
247                 chunk = list_entry(lchunk, struct sctp_chunk,
248                                    transmitted_list);
249                 sctp_chunk_fail(chunk, q->error);
250                 sctp_chunk_free(chunk);
251         }
252
253         /* Throw away any chunks in the retransmit queue. */
254         list_for_each_safe(lchunk, temp, &q->retransmit) {
255                 list_del_init(lchunk);
256                 chunk = list_entry(lchunk, struct sctp_chunk,
257                                    transmitted_list);
258                 sctp_chunk_fail(chunk, q->error);
259                 sctp_chunk_free(chunk);
260         }
261
262         /* Throw away any chunks that are in the abandoned queue. */
263         list_for_each_safe(lchunk, temp, &q->abandoned) {
264                 list_del_init(lchunk);
265                 chunk = list_entry(lchunk, struct sctp_chunk,
266                                    transmitted_list);
267                 sctp_chunk_fail(chunk, q->error);
268                 sctp_chunk_free(chunk);
269         }
270
271         /* Throw away any leftover data chunks. */
272         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
273
274                 /* Mark as send failure. */
275                 sctp_chunk_fail(chunk, q->error);
276                 sctp_chunk_free(chunk);
277         }
278
279         q->error = 0;
280
281         /* Throw away any leftover control chunks. */
282         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
283                 list_del_init(&chunk->list);
284                 sctp_chunk_free(chunk);
285         }
286 }
287
288 /* Free the outqueue structure and any related pending chunks.  */
289 void sctp_outq_free(struct sctp_outq *q)
290 {
291         /* Throw away leftover chunks. */
292         sctp_outq_teardown(q);
293
294         /* If we were kmalloc()'d, free the memory.  */
295         if (q->malloced)
296                 kfree(q);
297 }
298
299 /* Put a new chunk in an sctp_outq.  */
300 int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
301 {
302         int error = 0;
303
304         SCTP_DEBUG_PRINTK("sctp_outq_tail(%p, %p[%s])\n",
305                           q, chunk, chunk && chunk->chunk_hdr ?
306                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
307                           : "Illegal Chunk");
308
309         /* If it is data, queue it up, otherwise, send it
310          * immediately.
311          */
312         if (sctp_chunk_is_data(chunk)) {
313                 /* Is it OK to queue data chunks?  */
314                 /* From 9. Termination of Association
315                  *
316                  * When either endpoint performs a shutdown, the
317                  * association on each peer will stop accepting new
318                  * data from its user and only deliver data in queue
319                  * at the time of sending or receiving the SHUTDOWN
320                  * chunk.
321                  */
322                 switch (q->asoc->state) {
323                 case SCTP_STATE_CLOSED:
324                 case SCTP_STATE_SHUTDOWN_PENDING:
325                 case SCTP_STATE_SHUTDOWN_SENT:
326                 case SCTP_STATE_SHUTDOWN_RECEIVED:
327                 case SCTP_STATE_SHUTDOWN_ACK_SENT:
328                         /* Cannot send after transport endpoint shutdown */
329                         error = -ESHUTDOWN;
330                         break;
331
332                 default:
333                         SCTP_DEBUG_PRINTK("outqueueing (%p, %p[%s])\n",
334                           q, chunk, chunk && chunk->chunk_hdr ?
335                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
336                           : "Illegal Chunk");
337
338                         sctp_outq_tail_data(q, chunk);
339                         if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
340                                 SCTP_INC_STATS(SCTP_MIB_OUTUNORDERCHUNKS);
341                         else
342                                 SCTP_INC_STATS(SCTP_MIB_OUTORDERCHUNKS);
343                         q->empty = 0;
344                         break;
345                 }
346         } else {
347                 list_add_tail(&chunk->list, &q->control_chunk_list);
348                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
349         }
350
351         if (error < 0)
352                 return error;
353
354         if (!q->cork)
355                 error = sctp_outq_flush(q, 0);
356
357         return error;
358 }
359
360 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
361  * and the abandoned list are in ascending order.
362  */
363 static void sctp_insert_list(struct list_head *head, struct list_head *new)
364 {
365         struct list_head *pos;
366         struct sctp_chunk *nchunk, *lchunk;
367         __u32 ntsn, ltsn;
368         int done = 0;
369
370         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
371         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
372
373         list_for_each(pos, head) {
374                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
375                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
376                 if (TSN_lt(ntsn, ltsn)) {
377                         list_add(new, pos->prev);
378                         done = 1;
379                         break;
380                 }
381         }
382         if (!done)
383                 list_add_tail(new, head);
384 }
385
386 /* Mark all the eligible packets on a transport for retransmission.  */
387 void sctp_retransmit_mark(struct sctp_outq *q,
388                           struct sctp_transport *transport,
389                           __u8 reason)
390 {
391         struct list_head *lchunk, *ltemp;
392         struct sctp_chunk *chunk;
393
394         /* Walk through the specified transmitted queue.  */
395         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
396                 chunk = list_entry(lchunk, struct sctp_chunk,
397                                    transmitted_list);
398
399                 /* If the chunk is abandoned, move it to abandoned list. */
400                 if (sctp_chunk_abandoned(chunk)) {
401                         list_del_init(lchunk);
402                         sctp_insert_list(&q->abandoned, lchunk);
403
404                         /* If this chunk has not been previousely acked,
405                          * stop considering it 'outstanding'.  Our peer
406                          * will most likely never see it since it will
407                          * not be retransmitted
408                          */
409                         if (!chunk->tsn_gap_acked) {
410                                 if (chunk->transport)
411                                         chunk->transport->flight_size -=
412                                                         sctp_data_size(chunk);
413                                 q->outstanding_bytes -= sctp_data_size(chunk);
414                                 q->asoc->peer.rwnd += (sctp_data_size(chunk) +
415                                                         sizeof(struct sk_buff));
416                         }
417                         continue;
418                 }
419
420                 /* If we are doing  retransmission due to a timeout or pmtu
421                  * discovery, only the  chunks that are not yet acked should
422                  * be added to the retransmit queue.
423                  */
424                 if ((reason == SCTP_RTXR_FAST_RTX  &&
425                             (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
426                     (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
427                         /* RFC 2960 6.2.1 Processing a Received SACK
428                          *
429                          * C) Any time a DATA chunk is marked for
430                          * retransmission (via either T3-rtx timer expiration
431                          * (Section 6.3.3) or via fast retransmit
432                          * (Section 7.2.4)), add the data size of those
433                          * chunks to the rwnd.
434                          */
435                         q->asoc->peer.rwnd += (sctp_data_size(chunk) +
436                                                 sizeof(struct sk_buff));
437                         q->outstanding_bytes -= sctp_data_size(chunk);
438                         if (chunk->transport)
439                                 transport->flight_size -= sctp_data_size(chunk);
440
441                         /* sctpimpguide-05 Section 2.8.2
442                          * M5) If a T3-rtx timer expires, the
443                          * 'TSN.Missing.Report' of all affected TSNs is set
444                          * to 0.
445                          */
446                         chunk->tsn_missing_report = 0;
447
448                         /* If a chunk that is being used for RTT measurement
449                          * has to be retransmitted, we cannot use this chunk
450                          * anymore for RTT measurements. Reset rto_pending so
451                          * that a new RTT measurement is started when a new
452                          * data chunk is sent.
453                          */
454                         if (chunk->rtt_in_progress) {
455                                 chunk->rtt_in_progress = 0;
456                                 transport->rto_pending = 0;
457                         }
458
459                         /* Move the chunk to the retransmit queue. The chunks
460                          * on the retransmit queue are always kept in order.
461                          */
462                         list_del_init(lchunk);
463                         sctp_insert_list(&q->retransmit, lchunk);
464                 }
465         }
466
467         SCTP_DEBUG_PRINTK("%s: transport: %p, reason: %d, "
468                           "cwnd: %d, ssthresh: %d, flight_size: %d, "
469                           "pba: %d\n", __func__,
470                           transport, reason,
471                           transport->cwnd, transport->ssthresh,
472                           transport->flight_size,
473                           transport->partial_bytes_acked);
474
475 }
476
477 /* Mark all the eligible packets on a transport for retransmission and force
478  * one packet out.
479  */
480 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
481                      sctp_retransmit_reason_t reason)
482 {
483         int error = 0;
484
485         switch(reason) {
486         case SCTP_RTXR_T3_RTX:
487                 SCTP_INC_STATS(SCTP_MIB_T3_RETRANSMITS);
488                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
489                 /* Update the retran path if the T3-rtx timer has expired for
490                  * the current retran path.
491                  */
492                 if (transport == transport->asoc->peer.retran_path)
493                         sctp_assoc_update_retran_path(transport->asoc);
494                 transport->asoc->rtx_data_chunks +=
495                         transport->asoc->unack_data;
496                 break;
497         case SCTP_RTXR_FAST_RTX:
498                 SCTP_INC_STATS(SCTP_MIB_FAST_RETRANSMITS);
499                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
500                 q->fast_rtx = 1;
501                 break;
502         case SCTP_RTXR_PMTUD:
503                 SCTP_INC_STATS(SCTP_MIB_PMTUD_RETRANSMITS);
504                 break;
505         case SCTP_RTXR_T1_RTX:
506                 SCTP_INC_STATS(SCTP_MIB_T1_RETRANSMITS);
507                 transport->asoc->init_retries++;
508                 break;
509         default:
510                 BUG();
511         }
512
513         sctp_retransmit_mark(q, transport, reason);
514
515         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
516          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
517          * following the procedures outlined in C1 - C5.
518          */
519         if (reason == SCTP_RTXR_T3_RTX)
520                 sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
521
522         /* Flush the queues only on timeout, since fast_rtx is only
523          * triggered during sack processing and the queue
524          * will be flushed at the end.
525          */
526         if (reason != SCTP_RTXR_FAST_RTX)
527                 error = sctp_outq_flush(q, /* rtx_timeout */ 1);
528
529         if (error)
530                 q->asoc->base.sk->sk_err = -error;
531 }
532
533 /*
534  * Transmit DATA chunks on the retransmit queue.  Upon return from
535  * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
536  * need to be transmitted by the caller.
537  * We assume that pkt->transport has already been set.
538  *
539  * The return value is a normal kernel error return value.
540  */
541 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
542                                int rtx_timeout, int *start_timer)
543 {
544         struct list_head *lqueue;
545         struct sctp_transport *transport = pkt->transport;
546         sctp_xmit_t status;
547         struct sctp_chunk *chunk, *chunk1;
548         int fast_rtx;
549         int error = 0;
550         int timer = 0;
551         int done = 0;
552
553         lqueue = &q->retransmit;
554         fast_rtx = q->fast_rtx;
555
556         /* This loop handles time-out retransmissions, fast retransmissions,
557          * and retransmissions due to opening of whindow.
558          *
559          * RFC 2960 6.3.3 Handle T3-rtx Expiration
560          *
561          * E3) Determine how many of the earliest (i.e., lowest TSN)
562          * outstanding DATA chunks for the address for which the
563          * T3-rtx has expired will fit into a single packet, subject
564          * to the MTU constraint for the path corresponding to the
565          * destination transport address to which the retransmission
566          * is being sent (this may be different from the address for
567          * which the timer expires [see Section 6.4]). Call this value
568          * K. Bundle and retransmit those K DATA chunks in a single
569          * packet to the destination endpoint.
570          *
571          * [Just to be painfully clear, if we are retransmitting
572          * because a timeout just happened, we should send only ONE
573          * packet of retransmitted data.]
574          *
575          * For fast retransmissions we also send only ONE packet.  However,
576          * if we are just flushing the queue due to open window, we'll
577          * try to send as much as possible.
578          */
579         list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
580                 /* If the chunk is abandoned, move it to abandoned list. */
581                 if (sctp_chunk_abandoned(chunk)) {
582                         list_del_init(&chunk->transmitted_list);
583                         sctp_insert_list(&q->abandoned,
584                                          &chunk->transmitted_list);
585                         continue;
586                 }
587
588                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
589                  * simple approach is just to move such TSNs out of the
590                  * way and into a 'transmitted' queue and skip to the
591                  * next chunk.
592                  */
593                 if (chunk->tsn_gap_acked) {
594                         list_del(&chunk->transmitted_list);
595                         list_add_tail(&chunk->transmitted_list,
596                                         &transport->transmitted);
597                         continue;
598                 }
599
600                 /* If we are doing fast retransmit, ignore non-fast_rtransmit
601                  * chunks
602                  */
603                 if (fast_rtx && !chunk->fast_retransmit)
604                         continue;
605
606 redo:
607                 /* Attempt to append this chunk to the packet. */
608                 status = sctp_packet_append_chunk(pkt, chunk);
609
610                 switch (status) {
611                 case SCTP_XMIT_PMTU_FULL:
612                         if (!pkt->has_data && !pkt->has_cookie_echo) {
613                                 /* If this packet did not contain DATA then
614                                  * retransmission did not happen, so do it
615                                  * again.  We'll ignore the error here since
616                                  * control chunks are already freed so there
617                                  * is nothing we can do.
618                                  */
619                                 sctp_packet_transmit(pkt);
620                                 goto redo;
621                         }
622
623                         /* Send this packet.  */
624                         error = sctp_packet_transmit(pkt);
625
626                         /* If we are retransmitting, we should only
627                          * send a single packet.
628                          * Otherwise, try appending this chunk again.
629                          */
630                         if (rtx_timeout || fast_rtx)
631                                 done = 1;
632                         else
633                                 goto redo;
634
635                         /* Bundle next chunk in the next round.  */
636                         break;
637
638                 case SCTP_XMIT_RWND_FULL:
639                         /* Send this packet. */
640                         error = sctp_packet_transmit(pkt);
641
642                         /* Stop sending DATA as there is no more room
643                          * at the receiver.
644                          */
645                         done = 1;
646                         break;
647
648                 case SCTP_XMIT_NAGLE_DELAY:
649                         /* Send this packet. */
650                         error = sctp_packet_transmit(pkt);
651
652                         /* Stop sending DATA because of nagle delay. */
653                         done = 1;
654                         break;
655
656                 default:
657                         /* The append was successful, so add this chunk to
658                          * the transmitted list.
659                          */
660                         list_del(&chunk->transmitted_list);
661                         list_add_tail(&chunk->transmitted_list,
662                                         &transport->transmitted);
663
664                         /* Mark the chunk as ineligible for fast retransmit
665                          * after it is retransmitted.
666                          */
667                         if (chunk->fast_retransmit == SCTP_NEED_FRTX)
668                                 chunk->fast_retransmit = SCTP_DONT_FRTX;
669
670                         q->empty = 0;
671                         break;
672                 }
673
674                 /* Set the timer if there were no errors */
675                 if (!error && !timer)
676                         timer = 1;
677
678                 if (done)
679                         break;
680         }
681
682         /* If we are here due to a retransmit timeout or a fast
683          * retransmit and if there are any chunks left in the retransmit
684          * queue that could not fit in the PMTU sized packet, they need
685          * to be marked as ineligible for a subsequent fast retransmit.
686          */
687         if (rtx_timeout || fast_rtx) {
688                 list_for_each_entry(chunk1, lqueue, transmitted_list) {
689                         if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
690                                 chunk1->fast_retransmit = SCTP_DONT_FRTX;
691                 }
692         }
693
694         *start_timer = timer;
695
696         /* Clear fast retransmit hint */
697         if (fast_rtx)
698                 q->fast_rtx = 0;
699
700         return error;
701 }
702
703 /* Cork the outqueue so queued chunks are really queued. */
704 int sctp_outq_uncork(struct sctp_outq *q)
705 {
706         int error = 0;
707         if (q->cork)
708                 q->cork = 0;
709         error = sctp_outq_flush(q, 0);
710         return error;
711 }
712
713
714 /*
715  * Try to flush an outqueue.
716  *
717  * Description: Send everything in q which we legally can, subject to
718  * congestion limitations.
719  * * Note: This function can be called from multiple contexts so appropriate
720  * locking concerns must be made.  Today we use the sock lock to protect
721  * this function.
722  */
723 static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
724 {
725         struct sctp_packet *packet;
726         struct sctp_packet singleton;
727         struct sctp_association *asoc = q->asoc;
728         __u16 sport = asoc->base.bind_addr.port;
729         __u16 dport = asoc->peer.port;
730         __u32 vtag = asoc->peer.i.init_tag;
731         struct sctp_transport *transport = NULL;
732         struct sctp_transport *new_transport;
733         struct sctp_chunk *chunk, *tmp;
734         sctp_xmit_t status;
735         int error = 0;
736         int start_timer = 0;
737         int one_packet = 0;
738
739         /* These transports have chunks to send. */
740         struct list_head transport_list;
741         struct list_head *ltransport;
742
743         INIT_LIST_HEAD(&transport_list);
744         packet = NULL;
745
746         /*
747          * 6.10 Bundling
748          *   ...
749          *   When bundling control chunks with DATA chunks, an
750          *   endpoint MUST place control chunks first in the outbound
751          *   SCTP packet.  The transmitter MUST transmit DATA chunks
752          *   within a SCTP packet in increasing order of TSN.
753          *   ...
754          */
755
756         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
757                 list_del_init(&chunk->list);
758
759                 /* Pick the right transport to use. */
760                 new_transport = chunk->transport;
761
762                 if (!new_transport) {
763                         /*
764                          * If we have a prior transport pointer, see if
765                          * the destination address of the chunk
766                          * matches the destination address of the
767                          * current transport.  If not a match, then
768                          * try to look up the transport with a given
769                          * destination address.  We do this because
770                          * after processing ASCONFs, we may have new
771                          * transports created.
772                          */
773                         if (transport &&
774                             sctp_cmp_addr_exact(&chunk->dest,
775                                                 &transport->ipaddr))
776                                         new_transport = transport;
777                         else
778                                 new_transport = sctp_assoc_lookup_paddr(asoc,
779                                                                 &chunk->dest);
780
781                         /* if we still don't have a new transport, then
782                          * use the current active path.
783                          */
784                         if (!new_transport)
785                                 new_transport = asoc->peer.active_path;
786                 } else if ((new_transport->state == SCTP_INACTIVE) ||
787                            (new_transport->state == SCTP_UNCONFIRMED)) {
788                         /* If the chunk is Heartbeat or Heartbeat Ack,
789                          * send it to chunk->transport, even if it's
790                          * inactive.
791                          *
792                          * 3.3.6 Heartbeat Acknowledgement:
793                          * ...
794                          * A HEARTBEAT ACK is always sent to the source IP
795                          * address of the IP datagram containing the
796                          * HEARTBEAT chunk to which this ack is responding.
797                          * ...
798                          *
799                          * ASCONF_ACKs also must be sent to the source.
800                          */
801                         if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
802                             chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK &&
803                             chunk->chunk_hdr->type != SCTP_CID_ASCONF_ACK)
804                                 new_transport = asoc->peer.active_path;
805                 }
806
807                 /* Are we switching transports?
808                  * Take care of transport locks.
809                  */
810                 if (new_transport != transport) {
811                         transport = new_transport;
812                         if (list_empty(&transport->send_ready)) {
813                                 list_add_tail(&transport->send_ready,
814                                               &transport_list);
815                         }
816                         packet = &transport->packet;
817                         sctp_packet_config(packet, vtag,
818                                            asoc->peer.ecn_capable);
819                 }
820
821                 switch (chunk->chunk_hdr->type) {
822                 /*
823                  * 6.10 Bundling
824                  *   ...
825                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
826                  *   COMPLETE with any other chunks.  [Send them immediately.]
827                  */
828                 case SCTP_CID_INIT:
829                 case SCTP_CID_INIT_ACK:
830                 case SCTP_CID_SHUTDOWN_COMPLETE:
831                         sctp_packet_init(&singleton, transport, sport, dport);
832                         sctp_packet_config(&singleton, vtag, 0);
833                         sctp_packet_append_chunk(&singleton, chunk);
834                         error = sctp_packet_transmit(&singleton);
835                         if (error < 0)
836                                 return error;
837                         break;
838
839                 case SCTP_CID_ABORT:
840                         if (sctp_test_T_bit(chunk)) {
841                                 packet->vtag = asoc->c.my_vtag;
842                         }
843                 /* The following chunks are "response" chunks, i.e.
844                  * they are generated in response to something we
845                  * received.  If we are sending these, then we can
846                  * send only 1 packet containing these chunks.
847                  */
848                 case SCTP_CID_HEARTBEAT_ACK:
849                 case SCTP_CID_SHUTDOWN_ACK:
850                 case SCTP_CID_COOKIE_ACK:
851                 case SCTP_CID_COOKIE_ECHO:
852                 case SCTP_CID_ERROR:
853                 case SCTP_CID_ECN_CWR:
854                 case SCTP_CID_ASCONF_ACK:
855                         one_packet = 1;
856                         /* Fall through */
857
858                 case SCTP_CID_SACK:
859                 case SCTP_CID_HEARTBEAT:
860                 case SCTP_CID_SHUTDOWN:
861                 case SCTP_CID_ECN_ECNE:
862                 case SCTP_CID_ASCONF:
863                 case SCTP_CID_FWD_TSN:
864                         status = sctp_packet_transmit_chunk(packet, chunk,
865                                                             one_packet);
866                         if (status  != SCTP_XMIT_OK) {
867                                 /* put the chunk back */
868                                 list_add(&chunk->list, &q->control_chunk_list);
869                         } else if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN) {
870                                 /* PR-SCTP C5) If a FORWARD TSN is sent, the
871                                  * sender MUST assure that at least one T3-rtx
872                                  * timer is running.
873                                  */
874                                 sctp_transport_reset_timers(transport);
875                         }
876                         break;
877
878                 default:
879                         /* We built a chunk with an illegal type! */
880                         BUG();
881                 }
882         }
883
884         /* Is it OK to send data chunks?  */
885         switch (asoc->state) {
886         case SCTP_STATE_COOKIE_ECHOED:
887                 /* Only allow bundling when this packet has a COOKIE-ECHO
888                  * chunk.
889                  */
890                 if (!packet || !packet->has_cookie_echo)
891                         break;
892
893                 /* fallthru */
894         case SCTP_STATE_ESTABLISHED:
895         case SCTP_STATE_SHUTDOWN_PENDING:
896         case SCTP_STATE_SHUTDOWN_RECEIVED:
897                 /*
898                  * RFC 2960 6.1  Transmission of DATA Chunks
899                  *
900                  * C) When the time comes for the sender to transmit,
901                  * before sending new DATA chunks, the sender MUST
902                  * first transmit any outstanding DATA chunks which
903                  * are marked for retransmission (limited by the
904                  * current cwnd).
905                  */
906                 if (!list_empty(&q->retransmit)) {
907                         if (transport == asoc->peer.retran_path)
908                                 goto retran;
909
910                         /* Switch transports & prepare the packet.  */
911
912                         transport = asoc->peer.retran_path;
913
914                         if (list_empty(&transport->send_ready)) {
915                                 list_add_tail(&transport->send_ready,
916                                               &transport_list);
917                         }
918
919                         packet = &transport->packet;
920                         sctp_packet_config(packet, vtag,
921                                            asoc->peer.ecn_capable);
922                 retran:
923                         error = sctp_outq_flush_rtx(q, packet,
924                                                     rtx_timeout, &start_timer);
925
926                         if (start_timer)
927                                 sctp_transport_reset_timers(transport);
928
929                         /* This can happen on COOKIE-ECHO resend.  Only
930                          * one chunk can get bundled with a COOKIE-ECHO.
931                          */
932                         if (packet->has_cookie_echo)
933                                 goto sctp_flush_out;
934
935                         /* Don't send new data if there is still data
936                          * waiting to retransmit.
937                          */
938                         if (!list_empty(&q->retransmit))
939                                 goto sctp_flush_out;
940                 }
941
942                 /* Apply Max.Burst limitation to the current transport in
943                  * case it will be used for new data.  We are going to
944                  * rest it before we return, but we want to apply the limit
945                  * to the currently queued data.
946                  */
947                 if (transport)
948                         sctp_transport_burst_limited(transport);
949
950                 /* Finally, transmit new packets.  */
951                 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
952                         /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
953                          * stream identifier.
954                          */
955                         if (chunk->sinfo.sinfo_stream >=
956                             asoc->c.sinit_num_ostreams) {
957
958                                 /* Mark as failed send. */
959                                 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
960                                 sctp_chunk_free(chunk);
961                                 continue;
962                         }
963
964                         /* Has this chunk expired? */
965                         if (sctp_chunk_abandoned(chunk)) {
966                                 sctp_chunk_fail(chunk, 0);
967                                 sctp_chunk_free(chunk);
968                                 continue;
969                         }
970
971                         /* If there is a specified transport, use it.
972                          * Otherwise, we want to use the active path.
973                          */
974                         new_transport = chunk->transport;
975                         if (!new_transport ||
976                             ((new_transport->state == SCTP_INACTIVE) ||
977                              (new_transport->state == SCTP_UNCONFIRMED)))
978                                 new_transport = asoc->peer.active_path;
979
980                         /* Change packets if necessary.  */
981                         if (new_transport != transport) {
982                                 transport = new_transport;
983
984                                 /* Schedule to have this transport's
985                                  * packet flushed.
986                                  */
987                                 if (list_empty(&transport->send_ready)) {
988                                         list_add_tail(&transport->send_ready,
989                                                       &transport_list);
990                                 }
991
992                                 packet = &transport->packet;
993                                 sctp_packet_config(packet, vtag,
994                                                    asoc->peer.ecn_capable);
995                                 /* We've switched transports, so apply the
996                                  * Burst limit to the new transport.
997                                  */
998                                 sctp_transport_burst_limited(transport);
999                         }
1000
1001                         SCTP_DEBUG_PRINTK("sctp_outq_flush(%p, %p[%s]), ",
1002                                           q, chunk,
1003                                           chunk && chunk->chunk_hdr ?
1004                                           sctp_cname(SCTP_ST_CHUNK(
1005                                                   chunk->chunk_hdr->type))
1006                                           : "Illegal Chunk");
1007
1008                         SCTP_DEBUG_PRINTK("TX TSN 0x%x skb->head "
1009                                         "%p skb->users %d.\n",
1010                                         ntohl(chunk->subh.data_hdr->tsn),
1011                                         chunk->skb ?chunk->skb->head : NULL,
1012                                         chunk->skb ?
1013                                         atomic_read(&chunk->skb->users) : -1);
1014
1015                         /* Add the chunk to the packet.  */
1016                         status = sctp_packet_transmit_chunk(packet, chunk, 0);
1017
1018                         switch (status) {
1019                         case SCTP_XMIT_PMTU_FULL:
1020                         case SCTP_XMIT_RWND_FULL:
1021                         case SCTP_XMIT_NAGLE_DELAY:
1022                                 /* We could not append this chunk, so put
1023                                  * the chunk back on the output queue.
1024                                  */
1025                                 SCTP_DEBUG_PRINTK("sctp_outq_flush: could "
1026                                         "not transmit TSN: 0x%x, status: %d\n",
1027                                         ntohl(chunk->subh.data_hdr->tsn),
1028                                         status);
1029                                 sctp_outq_head_data(q, chunk);
1030                                 goto sctp_flush_out;
1031                                 break;
1032
1033                         case SCTP_XMIT_OK:
1034                                 /* The sender is in the SHUTDOWN-PENDING state,
1035                                  * The sender MAY set the I-bit in the DATA
1036                                  * chunk header.
1037                                  */
1038                                 if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1039                                         chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1040
1041                                 break;
1042
1043                         default:
1044                                 BUG();
1045                         }
1046
1047                         /* BUG: We assume that the sctp_packet_transmit()
1048                          * call below will succeed all the time and add the
1049                          * chunk to the transmitted list and restart the
1050                          * timers.
1051                          * It is possible that the call can fail under OOM
1052                          * conditions.
1053                          *
1054                          * Is this really a problem?  Won't this behave
1055                          * like a lost TSN?
1056                          */
1057                         list_add_tail(&chunk->transmitted_list,
1058                                       &transport->transmitted);
1059
1060                         sctp_transport_reset_timers(transport);
1061
1062                         q->empty = 0;
1063
1064                         /* Only let one DATA chunk get bundled with a
1065                          * COOKIE-ECHO chunk.
1066                          */
1067                         if (packet->has_cookie_echo)
1068                                 goto sctp_flush_out;
1069                 }
1070                 break;
1071
1072         default:
1073                 /* Do nothing.  */
1074                 break;
1075         }
1076
1077 sctp_flush_out:
1078
1079         /* Before returning, examine all the transports touched in
1080          * this call.  Right now, we bluntly force clear all the
1081          * transports.  Things might change after we implement Nagle.
1082          * But such an examination is still required.
1083          *
1084          * --xguo
1085          */
1086         while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
1087                 struct sctp_transport *t = list_entry(ltransport,
1088                                                       struct sctp_transport,
1089                                                       send_ready);
1090                 packet = &t->packet;
1091                 if (!sctp_packet_empty(packet))
1092                         error = sctp_packet_transmit(packet);
1093
1094                 /* Clear the burst limited state, if any */
1095                 sctp_transport_burst_reset(t);
1096         }
1097
1098         return error;
1099 }
1100
1101 /* Update unack_data based on the incoming SACK chunk */
1102 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1103                                         struct sctp_sackhdr *sack)
1104 {
1105         sctp_sack_variable_t *frags;
1106         __u16 unack_data;
1107         int i;
1108
1109         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1110
1111         frags = sack->variable;
1112         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1113                 unack_data -= ((ntohs(frags[i].gab.end) -
1114                                 ntohs(frags[i].gab.start) + 1));
1115         }
1116
1117         assoc->unack_data = unack_data;
1118 }
1119
1120 /* This is where we REALLY process a SACK.
1121  *
1122  * Process the SACK against the outqueue.  Mostly, this just frees
1123  * things off the transmitted queue.
1124  */
1125 int sctp_outq_sack(struct sctp_outq *q, struct sctp_sackhdr *sack)
1126 {
1127         struct sctp_association *asoc = q->asoc;
1128         struct sctp_transport *transport;
1129         struct sctp_chunk *tchunk = NULL;
1130         struct list_head *lchunk, *transport_list, *temp;
1131         sctp_sack_variable_t *frags = sack->variable;
1132         __u32 sack_ctsn, ctsn, tsn;
1133         __u32 highest_tsn, highest_new_tsn;
1134         __u32 sack_a_rwnd;
1135         unsigned outstanding;
1136         struct sctp_transport *primary = asoc->peer.primary_path;
1137         int count_of_newacks = 0;
1138         int gap_ack_blocks;
1139         u8 accum_moved = 0;
1140
1141         /* Grab the association's destination address list. */
1142         transport_list = &asoc->peer.transport_addr_list;
1143
1144         sack_ctsn = ntohl(sack->cum_tsn_ack);
1145         gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1146         /*
1147          * SFR-CACC algorithm:
1148          * On receipt of a SACK the sender SHOULD execute the
1149          * following statements.
1150          *
1151          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1152          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1153          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1154          * all destinations.
1155          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1156          * is set the receiver of the SACK MUST take the following actions:
1157          *
1158          * A) Initialize the cacc_saw_newack to 0 for all destination
1159          * addresses.
1160          *
1161          * Only bother if changeover_active is set. Otherwise, this is
1162          * totally suboptimal to do on every SACK.
1163          */
1164         if (primary->cacc.changeover_active) {
1165                 u8 clear_cycling = 0;
1166
1167                 if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1168                         primary->cacc.changeover_active = 0;
1169                         clear_cycling = 1;
1170                 }
1171
1172                 if (clear_cycling || gap_ack_blocks) {
1173                         list_for_each_entry(transport, transport_list,
1174                                         transports) {
1175                                 if (clear_cycling)
1176                                         transport->cacc.cycling_changeover = 0;
1177                                 if (gap_ack_blocks)
1178                                         transport->cacc.cacc_saw_newack = 0;
1179                         }
1180                 }
1181         }
1182
1183         /* Get the highest TSN in the sack. */
1184         highest_tsn = sack_ctsn;
1185         if (gap_ack_blocks)
1186                 highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1187
1188         if (TSN_lt(asoc->highest_sacked, highest_tsn))
1189                 asoc->highest_sacked = highest_tsn;
1190
1191         highest_new_tsn = sack_ctsn;
1192
1193         /* Run through the retransmit queue.  Credit bytes received
1194          * and free those chunks that we can.
1195          */
1196         sctp_check_transmitted(q, &q->retransmit, NULL, sack, &highest_new_tsn);
1197
1198         /* Run through the transmitted queue.
1199          * Credit bytes received and free those chunks which we can.
1200          *
1201          * This is a MASSIVE candidate for optimization.
1202          */
1203         list_for_each_entry(transport, transport_list, transports) {
1204                 sctp_check_transmitted(q, &transport->transmitted,
1205                                        transport, sack, &highest_new_tsn);
1206                 /*
1207                  * SFR-CACC algorithm:
1208                  * C) Let count_of_newacks be the number of
1209                  * destinations for which cacc_saw_newack is set.
1210                  */
1211                 if (transport->cacc.cacc_saw_newack)
1212                         count_of_newacks ++;
1213         }
1214
1215         /* Move the Cumulative TSN Ack Point if appropriate.  */
1216         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1217                 asoc->ctsn_ack_point = sack_ctsn;
1218                 accum_moved = 1;
1219         }
1220
1221         if (gap_ack_blocks) {
1222
1223                 if (asoc->fast_recovery && accum_moved)
1224                         highest_new_tsn = highest_tsn;
1225
1226                 list_for_each_entry(transport, transport_list, transports)
1227                         sctp_mark_missing(q, &transport->transmitted, transport,
1228                                           highest_new_tsn, count_of_newacks);
1229         }
1230
1231         /* Update unack_data field in the assoc. */
1232         sctp_sack_update_unack_data(asoc, sack);
1233
1234         ctsn = asoc->ctsn_ack_point;
1235
1236         /* Throw away stuff rotting on the sack queue.  */
1237         list_for_each_safe(lchunk, temp, &q->sacked) {
1238                 tchunk = list_entry(lchunk, struct sctp_chunk,
1239                                     transmitted_list);
1240                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1241                 if (TSN_lte(tsn, ctsn)) {
1242                         list_del_init(&tchunk->transmitted_list);
1243                         sctp_chunk_free(tchunk);
1244                 }
1245         }
1246
1247         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1248          *     number of bytes still outstanding after processing the
1249          *     Cumulative TSN Ack and the Gap Ack Blocks.
1250          */
1251
1252         sack_a_rwnd = ntohl(sack->a_rwnd);
1253         outstanding = q->outstanding_bytes;
1254
1255         if (outstanding < sack_a_rwnd)
1256                 sack_a_rwnd -= outstanding;
1257         else
1258                 sack_a_rwnd = 0;
1259
1260         asoc->peer.rwnd = sack_a_rwnd;
1261
1262         sctp_generate_fwdtsn(q, sack_ctsn);
1263
1264         SCTP_DEBUG_PRINTK("%s: sack Cumulative TSN Ack is 0x%x.\n",
1265                           __func__, sack_ctsn);
1266         SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
1267                           "%p is 0x%x. Adv peer ack point: 0x%x\n",
1268                           __func__, asoc, ctsn, asoc->adv_peer_ack_point);
1269
1270         /* See if all chunks are acked.
1271          * Make sure the empty queue handler will get run later.
1272          */
1273         q->empty = (list_empty(&q->out_chunk_list) &&
1274                     list_empty(&q->retransmit));
1275         if (!q->empty)
1276                 goto finish;
1277
1278         list_for_each_entry(transport, transport_list, transports) {
1279                 q->empty = q->empty && list_empty(&transport->transmitted);
1280                 if (!q->empty)
1281                         goto finish;
1282         }
1283
1284         SCTP_DEBUG_PRINTK("sack queue is empty.\n");
1285 finish:
1286         return q->empty;
1287 }
1288
1289 /* Is the outqueue empty?  */
1290 int sctp_outq_is_empty(const struct sctp_outq *q)
1291 {
1292         return q->empty;
1293 }
1294
1295 /********************************************************************
1296  * 2nd Level Abstractions
1297  ********************************************************************/
1298
1299 /* Go through a transport's transmitted list or the association's retransmit
1300  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1301  * The retransmit list will not have an associated transport.
1302  *
1303  * I added coherent debug information output.   --xguo
1304  *
1305  * Instead of printing 'sacked' or 'kept' for each TSN on the
1306  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1307  * KEPT TSN6-TSN7, etc.
1308  */
1309 static void sctp_check_transmitted(struct sctp_outq *q,
1310                                    struct list_head *transmitted_queue,
1311                                    struct sctp_transport *transport,
1312                                    struct sctp_sackhdr *sack,
1313                                    __u32 *highest_new_tsn_in_sack)
1314 {
1315         struct list_head *lchunk;
1316         struct sctp_chunk *tchunk;
1317         struct list_head tlist;
1318         __u32 tsn;
1319         __u32 sack_ctsn;
1320         __u32 rtt;
1321         __u8 restart_timer = 0;
1322         int bytes_acked = 0;
1323         int migrate_bytes = 0;
1324
1325         /* These state variables are for coherent debug output. --xguo */
1326
1327 #if SCTP_DEBUG
1328         __u32 dbg_ack_tsn = 0;  /* An ACKed TSN range starts here... */
1329         __u32 dbg_last_ack_tsn = 0;  /* ...and finishes here.        */
1330         __u32 dbg_kept_tsn = 0; /* An un-ACKed range starts here...  */
1331         __u32 dbg_last_kept_tsn = 0; /* ...and finishes here.        */
1332
1333         /* 0 : The last TSN was ACKed.
1334          * 1 : The last TSN was NOT ACKed (i.e. KEPT).
1335          * -1: We need to initialize.
1336          */
1337         int dbg_prt_state = -1;
1338 #endif /* SCTP_DEBUG */
1339
1340         sack_ctsn = ntohl(sack->cum_tsn_ack);
1341
1342         INIT_LIST_HEAD(&tlist);
1343
1344         /* The while loop will skip empty transmitted queues. */
1345         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1346                 tchunk = list_entry(lchunk, struct sctp_chunk,
1347                                     transmitted_list);
1348
1349                 if (sctp_chunk_abandoned(tchunk)) {
1350                         /* Move the chunk to abandoned list. */
1351                         sctp_insert_list(&q->abandoned, lchunk);
1352
1353                         /* If this chunk has not been acked, stop
1354                          * considering it as 'outstanding'.
1355                          */
1356                         if (!tchunk->tsn_gap_acked) {
1357                                 if (tchunk->transport)
1358                                         tchunk->transport->flight_size -=
1359                                                         sctp_data_size(tchunk);
1360                                 q->outstanding_bytes -= sctp_data_size(tchunk);
1361                         }
1362                         continue;
1363                 }
1364
1365                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1366                 if (sctp_acked(sack, tsn)) {
1367                         /* If this queue is the retransmit queue, the
1368                          * retransmit timer has already reclaimed
1369                          * the outstanding bytes for this chunk, so only
1370                          * count bytes associated with a transport.
1371                          */
1372                         if (transport) {
1373                                 /* If this chunk is being used for RTT
1374                                  * measurement, calculate the RTT and update
1375                                  * the RTO using this value.
1376                                  *
1377                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1378                                  * MUST NOT be made using packets that were
1379                                  * retransmitted (and thus for which it is
1380                                  * ambiguous whether the reply was for the
1381                                  * first instance of the packet or a later
1382                                  * instance).
1383                                  */
1384                                 if (!tchunk->tsn_gap_acked &&
1385                                     tchunk->rtt_in_progress) {
1386                                         tchunk->rtt_in_progress = 0;
1387                                         rtt = jiffies - tchunk->sent_at;
1388                                         sctp_transport_update_rto(transport,
1389                                                                   rtt);
1390                                 }
1391                         }
1392
1393                         /* If the chunk hasn't been marked as ACKED,
1394                          * mark it and account bytes_acked if the
1395                          * chunk had a valid transport (it will not
1396                          * have a transport if ASCONF had deleted it
1397                          * while DATA was outstanding).
1398                          */
1399                         if (!tchunk->tsn_gap_acked) {
1400                                 tchunk->tsn_gap_acked = 1;
1401                                 *highest_new_tsn_in_sack = tsn;
1402                                 bytes_acked += sctp_data_size(tchunk);
1403                                 if (!tchunk->transport)
1404                                         migrate_bytes += sctp_data_size(tchunk);
1405                         }
1406
1407                         if (TSN_lte(tsn, sack_ctsn)) {
1408                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1409                                  *
1410                                  * R3) Whenever a SACK is received
1411                                  * that acknowledges the DATA chunk
1412                                  * with the earliest outstanding TSN
1413                                  * for that address, restart T3-rtx
1414                                  * timer for that address with its
1415                                  * current RTO.
1416                                  */
1417                                 restart_timer = 1;
1418
1419                                 if (!tchunk->tsn_gap_acked) {
1420                                         /*
1421                                          * SFR-CACC algorithm:
1422                                          * 2) If the SACK contains gap acks
1423                                          * and the flag CHANGEOVER_ACTIVE is
1424                                          * set the receiver of the SACK MUST
1425                                          * take the following action:
1426                                          *
1427                                          * B) For each TSN t being acked that
1428                                          * has not been acked in any SACK so
1429                                          * far, set cacc_saw_newack to 1 for
1430                                          * the destination that the TSN was
1431                                          * sent to.
1432                                          */
1433                                         if (transport &&
1434                                             sack->num_gap_ack_blocks &&
1435                                             q->asoc->peer.primary_path->cacc.
1436                                             changeover_active)
1437                                                 transport->cacc.cacc_saw_newack
1438                                                         = 1;
1439                                 }
1440
1441                                 list_add_tail(&tchunk->transmitted_list,
1442                                               &q->sacked);
1443                         } else {
1444                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1445                                  * M2) Each time a SACK arrives reporting
1446                                  * 'Stray DATA chunk(s)' record the highest TSN
1447                                  * reported as newly acknowledged, call this
1448                                  * value 'HighestTSNinSack'. A newly
1449                                  * acknowledged DATA chunk is one not
1450                                  * previously acknowledged in a SACK.
1451                                  *
1452                                  * When the SCTP sender of data receives a SACK
1453                                  * chunk that acknowledges, for the first time,
1454                                  * the receipt of a DATA chunk, all the still
1455                                  * unacknowledged DATA chunks whose TSN is
1456                                  * older than that newly acknowledged DATA
1457                                  * chunk, are qualified as 'Stray DATA chunks'.
1458                                  */
1459                                 list_add_tail(lchunk, &tlist);
1460                         }
1461
1462 #if SCTP_DEBUG
1463                         switch (dbg_prt_state) {
1464                         case 0: /* last TSN was ACKed */
1465                                 if (dbg_last_ack_tsn + 1 == tsn) {
1466                                         /* This TSN belongs to the
1467                                          * current ACK range.
1468                                          */
1469                                         break;
1470                                 }
1471
1472                                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1473                                         /* Display the end of the
1474                                          * current range.
1475                                          */
1476                                         SCTP_DEBUG_PRINTK_CONT("-%08x",
1477                                                                dbg_last_ack_tsn);
1478                                 }
1479
1480                                 /* Start a new range.  */
1481                                 SCTP_DEBUG_PRINTK_CONT(",%08x", tsn);
1482                                 dbg_ack_tsn = tsn;
1483                                 break;
1484
1485                         case 1: /* The last TSN was NOT ACKed. */
1486                                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1487                                         /* Display the end of current range. */
1488                                         SCTP_DEBUG_PRINTK_CONT("-%08x",
1489                                                                dbg_last_kept_tsn);
1490                                 }
1491
1492                                 SCTP_DEBUG_PRINTK_CONT("\n");
1493
1494                                 /* FALL THROUGH... */
1495                         default:
1496                                 /* This is the first-ever TSN we examined.  */
1497                                 /* Start a new range of ACK-ed TSNs.  */
1498                                 SCTP_DEBUG_PRINTK("ACKed: %08x", tsn);
1499                                 dbg_prt_state = 0;
1500                                 dbg_ack_tsn = tsn;
1501                         }
1502
1503                         dbg_last_ack_tsn = tsn;
1504 #endif /* SCTP_DEBUG */
1505
1506                 } else {
1507                         if (tchunk->tsn_gap_acked) {
1508                                 SCTP_DEBUG_PRINTK("%s: Receiver reneged on "
1509                                                   "data TSN: 0x%x\n",
1510                                                   __func__,
1511                                                   tsn);
1512                                 tchunk->tsn_gap_acked = 0;
1513
1514                                 if (tchunk->transport)
1515                                         bytes_acked -= sctp_data_size(tchunk);
1516
1517                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1518                                  *
1519                                  * R4) Whenever a SACK is received missing a
1520                                  * TSN that was previously acknowledged via a
1521                                  * Gap Ack Block, start T3-rtx for the
1522                                  * destination address to which the DATA
1523                                  * chunk was originally
1524                                  * transmitted if it is not already running.
1525                                  */
1526                                 restart_timer = 1;
1527                         }
1528
1529                         list_add_tail(lchunk, &tlist);
1530
1531 #if SCTP_DEBUG
1532                         /* See the above comments on ACK-ed TSNs. */
1533                         switch (dbg_prt_state) {
1534                         case 1:
1535                                 if (dbg_last_kept_tsn + 1 == tsn)
1536                                         break;
1537
1538                                 if (dbg_last_kept_tsn != dbg_kept_tsn)
1539                                         SCTP_DEBUG_PRINTK_CONT("-%08x",
1540                                                                dbg_last_kept_tsn);
1541
1542                                 SCTP_DEBUG_PRINTK_CONT(",%08x", tsn);
1543                                 dbg_kept_tsn = tsn;
1544                                 break;
1545
1546                         case 0:
1547                                 if (dbg_last_ack_tsn != dbg_ack_tsn)
1548                                         SCTP_DEBUG_PRINTK_CONT("-%08x",
1549                                                                dbg_last_ack_tsn);
1550                                 SCTP_DEBUG_PRINTK_CONT("\n");
1551
1552                                 /* FALL THROUGH... */
1553                         default:
1554                                 SCTP_DEBUG_PRINTK("KEPT: %08x",tsn);
1555                                 dbg_prt_state = 1;
1556                                 dbg_kept_tsn = tsn;
1557                         }
1558
1559                         dbg_last_kept_tsn = tsn;
1560 #endif /* SCTP_DEBUG */
1561                 }
1562         }
1563
1564 #if SCTP_DEBUG
1565         /* Finish off the last range, displaying its ending TSN.  */
1566         switch (dbg_prt_state) {
1567         case 0:
1568                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1569                         SCTP_DEBUG_PRINTK_CONT("-%08x\n", dbg_last_ack_tsn);
1570                 } else {
1571                         SCTP_DEBUG_PRINTK_CONT("\n");
1572                 }
1573         break;
1574
1575         case 1:
1576                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1577                         SCTP_DEBUG_PRINTK_CONT("-%08x\n", dbg_last_kept_tsn);
1578                 } else {
1579                         SCTP_DEBUG_PRINTK_CONT("\n");
1580                 }
1581         }
1582 #endif /* SCTP_DEBUG */
1583         if (transport) {
1584                 if (bytes_acked) {
1585                         /* We may have counted DATA that was migrated
1586                          * to this transport due to DEL-IP operation.
1587                          * Subtract those bytes, since the were never
1588                          * send on this transport and shouldn't be
1589                          * credited to this transport.
1590                          */
1591                         bytes_acked -= migrate_bytes;
1592
1593                         /* 8.2. When an outstanding TSN is acknowledged,
1594                          * the endpoint shall clear the error counter of
1595                          * the destination transport address to which the
1596                          * DATA chunk was last sent.
1597                          * The association's overall error counter is
1598                          * also cleared.
1599                          */
1600                         transport->error_count = 0;
1601                         transport->asoc->overall_error_count = 0;
1602
1603                         /* Mark the destination transport address as
1604                          * active if it is not so marked.
1605                          */
1606                         if ((transport->state == SCTP_INACTIVE) ||
1607                             (transport->state == SCTP_UNCONFIRMED)) {
1608                                 sctp_assoc_control_transport(
1609                                         transport->asoc,
1610                                         transport,
1611                                         SCTP_TRANSPORT_UP,
1612                                         SCTP_RECEIVED_SACK);
1613                         }
1614
1615                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1616                                                   bytes_acked);
1617
1618                         transport->flight_size -= bytes_acked;
1619                         if (transport->flight_size == 0)
1620                                 transport->partial_bytes_acked = 0;
1621                         q->outstanding_bytes -= bytes_acked + migrate_bytes;
1622                 } else {
1623                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1624                          * When a sender is doing zero window probing, it
1625                          * should not timeout the association if it continues
1626                          * to receive new packets from the receiver. The
1627                          * reason is that the receiver MAY keep its window
1628                          * closed for an indefinite time.
1629                          * A sender is doing zero window probing when the
1630                          * receiver's advertised window is zero, and there is
1631                          * only one data chunk in flight to the receiver.
1632                          */
1633                         if (!q->asoc->peer.rwnd &&
1634                             !list_empty(&tlist) &&
1635                             (sack_ctsn+2 == q->asoc->next_tsn)) {
1636                                 SCTP_DEBUG_PRINTK("%s: SACK received for zero "
1637                                                   "window probe: %u\n",
1638                                                   __func__, sack_ctsn);
1639                                 q->asoc->overall_error_count = 0;
1640                                 transport->error_count = 0;
1641                         }
1642                 }
1643
1644                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1645                  *
1646                  * R2) Whenever all outstanding data sent to an address have
1647                  * been acknowledged, turn off the T3-rtx timer of that
1648                  * address.
1649                  */
1650                 if (!transport->flight_size) {
1651                         if (timer_pending(&transport->T3_rtx_timer) &&
1652                             del_timer(&transport->T3_rtx_timer)) {
1653                                 sctp_transport_put(transport);
1654                         }
1655                 } else if (restart_timer) {
1656                         if (!mod_timer(&transport->T3_rtx_timer,
1657                                        jiffies + transport->rto))
1658                                 sctp_transport_hold(transport);
1659                 }
1660         }
1661
1662         list_splice(&tlist, transmitted_queue);
1663 }
1664
1665 /* Mark chunks as missing and consequently may get retransmitted. */
1666 static void sctp_mark_missing(struct sctp_outq *q,
1667                               struct list_head *transmitted_queue,
1668                               struct sctp_transport *transport,
1669                               __u32 highest_new_tsn_in_sack,
1670                               int count_of_newacks)
1671 {
1672         struct sctp_chunk *chunk;
1673         __u32 tsn;
1674         char do_fast_retransmit = 0;
1675         struct sctp_association *asoc = q->asoc;
1676         struct sctp_transport *primary = asoc->peer.primary_path;
1677
1678         list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1679
1680                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1681
1682                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1683                  * 'Unacknowledged TSN's', if the TSN number of an
1684                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1685                  * value, increment the 'TSN.Missing.Report' count on that
1686                  * chunk if it has NOT been fast retransmitted or marked for
1687                  * fast retransmit already.
1688                  */
1689                 if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1690                     !chunk->tsn_gap_acked &&
1691                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1692
1693                         /* SFR-CACC may require us to skip marking
1694                          * this chunk as missing.
1695                          */
1696                         if (!transport || !sctp_cacc_skip(primary,
1697                                                 chunk->transport,
1698                                                 count_of_newacks, tsn)) {
1699                                 chunk->tsn_missing_report++;
1700
1701                                 SCTP_DEBUG_PRINTK(
1702                                         "%s: TSN 0x%x missing counter: %d\n",
1703                                         __func__, tsn,
1704                                         chunk->tsn_missing_report);
1705                         }
1706                 }
1707                 /*
1708                  * M4) If any DATA chunk is found to have a
1709                  * 'TSN.Missing.Report'
1710                  * value larger than or equal to 3, mark that chunk for
1711                  * retransmission and start the fast retransmit procedure.
1712                  */
1713
1714                 if (chunk->tsn_missing_report >= 3) {
1715                         chunk->fast_retransmit = SCTP_NEED_FRTX;
1716                         do_fast_retransmit = 1;
1717                 }
1718         }
1719
1720         if (transport) {
1721                 if (do_fast_retransmit)
1722                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1723
1724                 SCTP_DEBUG_PRINTK("%s: transport: %p, cwnd: %d, "
1725                                   "ssthresh: %d, flight_size: %d, pba: %d\n",
1726                                   __func__, transport, transport->cwnd,
1727                                   transport->ssthresh, transport->flight_size,
1728                                   transport->partial_bytes_acked);
1729         }
1730 }
1731
1732 /* Is the given TSN acked by this packet?  */
1733 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1734 {
1735         int i;
1736         sctp_sack_variable_t *frags;
1737         __u16 gap;
1738         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1739
1740         if (TSN_lte(tsn, ctsn))
1741                 goto pass;
1742
1743         /* 3.3.4 Selective Acknowledgement (SACK) (3):
1744          *
1745          * Gap Ack Blocks:
1746          *  These fields contain the Gap Ack Blocks. They are repeated
1747          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1748          *  defined in the Number of Gap Ack Blocks field. All DATA
1749          *  chunks with TSNs greater than or equal to (Cumulative TSN
1750          *  Ack + Gap Ack Block Start) and less than or equal to
1751          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1752          *  Block are assumed to have been received correctly.
1753          */
1754
1755         frags = sack->variable;
1756         gap = tsn - ctsn;
1757         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1758                 if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1759                     TSN_lte(gap, ntohs(frags[i].gab.end)))
1760                         goto pass;
1761         }
1762
1763         return 0;
1764 pass:
1765         return 1;
1766 }
1767
1768 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1769                                     int nskips, __be16 stream)
1770 {
1771         int i;
1772
1773         for (i = 0; i < nskips; i++) {
1774                 if (skiplist[i].stream == stream)
1775                         return i;
1776         }
1777         return i;
1778 }
1779
1780 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1781 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1782 {
1783         struct sctp_association *asoc = q->asoc;
1784         struct sctp_chunk *ftsn_chunk = NULL;
1785         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1786         int nskips = 0;
1787         int skip_pos = 0;
1788         __u32 tsn;
1789         struct sctp_chunk *chunk;
1790         struct list_head *lchunk, *temp;
1791
1792         if (!asoc->peer.prsctp_capable)
1793                 return;
1794
1795         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1796          * received SACK.
1797          *
1798          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1799          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1800          */
1801         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1802                 asoc->adv_peer_ack_point = ctsn;
1803
1804         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1805          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1806          * the chunk next in the out-queue space is marked as "abandoned" as
1807          * shown in the following example:
1808          *
1809          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1810          * and the Advanced.Peer.Ack.Point is updated to this value:
1811          *
1812          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1813          *   normal SACK processing           local advancement
1814          *                ...                           ...
1815          *   Adv.Ack.Pt-> 102 acked                     102 acked
1816          *                103 abandoned                 103 abandoned
1817          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1818          *                105                           105
1819          *                106 acked                     106 acked
1820          *                ...                           ...
1821          *
1822          * In this example, the data sender successfully advanced the
1823          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1824          */
1825         list_for_each_safe(lchunk, temp, &q->abandoned) {
1826                 chunk = list_entry(lchunk, struct sctp_chunk,
1827                                         transmitted_list);
1828                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1829
1830                 /* Remove any chunks in the abandoned queue that are acked by
1831                  * the ctsn.
1832                  */
1833                 if (TSN_lte(tsn, ctsn)) {
1834                         list_del_init(lchunk);
1835                         sctp_chunk_free(chunk);
1836                 } else {
1837                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1838                                 asoc->adv_peer_ack_point = tsn;
1839                                 if (chunk->chunk_hdr->flags &
1840                                          SCTP_DATA_UNORDERED)
1841                                         continue;
1842                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1843                                                 nskips,
1844                                                 chunk->subh.data_hdr->stream);
1845                                 ftsn_skip_arr[skip_pos].stream =
1846                                         chunk->subh.data_hdr->stream;
1847                                 ftsn_skip_arr[skip_pos].ssn =
1848                                          chunk->subh.data_hdr->ssn;
1849                                 if (skip_pos == nskips)
1850                                         nskips++;
1851                                 if (nskips == 10)
1852                                         break;
1853                         } else
1854                                 break;
1855                 }
1856         }
1857
1858         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1859          * is greater than the Cumulative TSN ACK carried in the received
1860          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1861          * chunk containing the latest value of the
1862          * "Advanced.Peer.Ack.Point".
1863          *
1864          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1865          * list each stream and sequence number in the forwarded TSN. This
1866          * information will enable the receiver to easily find any
1867          * stranded TSN's waiting on stream reorder queues. Each stream
1868          * SHOULD only be reported once; this means that if multiple
1869          * abandoned messages occur in the same stream then only the
1870          * highest abandoned stream sequence number is reported. If the
1871          * total size of the FORWARD TSN does NOT fit in a single MTU then
1872          * the sender of the FORWARD TSN SHOULD lower the
1873          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1874          * single MTU.
1875          */
1876         if (asoc->adv_peer_ack_point > ctsn)
1877                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1878                                               nskips, &ftsn_skip_arr[0]);
1879
1880         if (ftsn_chunk) {
1881                 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1882                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
1883         }
1884 }