summaryrefslogtreecommitdiffstats
path: root/net/sctp/outqueue.c
blob: 5cb1aa5f067bcae7f4b74fd59927dd968c092785 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
// SPDX-License-Identifier: GPL-2.0-or-later
/* SCTP kernel implementation
 * (C) Copyright IBM Corp. 2001, 2004
 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001-2003 Intel Corp.
 *
 * This file is part of the SCTP kernel implementation
 *
 * These functions implement the sctp_outq class.   The outqueue handles
 * bundling and queueing of outgoing SCTP chunks.
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <linux-sctp@vger.kernel.org>
 *
 * Written or modified by:
 *    La Monte H.P. Yarroll <piggy@acm.org>
 *    Karl Knutson          <karl@athena.chicago.il.us>
 *    Perry Melange         <pmelange@null.cc.uic.edu>
 *    Xingang Guo           <xingang.guo@intel.com>
 *    Hui Huang 	    <hui.huang@nokia.com>
 *    Sridhar Samudrala     <sri@us.ibm.com>
 *    Jon Grimm             <jgrimm@us.ibm.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/types.h>
#include <linux/list.h>   /* For struct list_head */
#include <linux/socket.h>
#include <linux/ip.h>
#include <linux/slab.h>
#include <net/sock.h>	  /* For skb_set_owner_w */

#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>
#include <net/sctp/stream_sched.h>
#include <trace/events/sctp.h>

/* Declare internal functions here.  */
static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
static void sctp_check_transmitted(struct sctp_outq *q,
				   struct list_head *transmitted_queue,
				   struct sctp_transport *transport,
				   union sctp_addr *saddr,
				   struct sctp_sackhdr *sack,
				   __u32 *highest_new_tsn);

static void sctp_mark_missing(struct sctp_outq *q,
			      struct list_head *transmitted_queue,
			      struct sctp_transport *transport,
			      __u32 highest_new_tsn,
			      int count_of_newacks);

static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp);

/* Add data to the front of the queue. */
static inline void sctp_outq_head_data(struct sctp_outq *q,
				       struct sctp_chunk *ch)
{
	struct sctp_stream_out_ext *oute;
	__u16 stream;

	list_add(&ch->list, &q->out_chunk_list);
	q->out_qlen += ch->skb->len;

	stream = sctp_chunk_stream_no(ch);
	oute = SCTP_SO(&q->asoc->stream, stream)->ext;
	list_add(&ch->stream_list, &oute->outq);
}

/* Take data from the front of the queue. */
static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
{
	return q->sched->dequeue(q);
}

/* Add data chunk to the end of the queue. */
static inline void sctp_outq_tail_data(struct sctp_outq *q,
				       struct sctp_chunk *ch)
{
	struct sctp_stream_out_ext *oute;
	__u16 stream;

	list_add_tail(&ch->list, &q->out_chunk_list);
	q->out_qlen += ch->skb->len;

	stream = sctp_chunk_stream_no(ch);
	oute = SCTP_SO(&q->asoc->stream, stream)->ext;
	list_add_tail(&ch->stream_list, &oute->outq);
}

/*
 * SFR-CACC algorithm:
 * D) If count_of_newacks is greater than or equal to 2
 * and t was not sent to the current primary then the
 * sender MUST NOT increment missing report count for t.
 */
static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
				       struct sctp_transport *transport,
				       int count_of_newacks)
{
	if (count_of_newacks >= 2 && transport != primary)
		return 1;
	return 0;
}

/*
 * SFR-CACC algorithm:
 * F) If count_of_newacks is less than 2, let d be the
 * destination to which t was sent. If cacc_saw_newack
 * is 0 for destination d, then the sender MUST NOT
 * increment missing report count for t.
 */
static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
				       int count_of_newacks)
{
	if (count_of_newacks < 2 &&
			(transport && !transport->cacc.cacc_saw_newack))
		return 1;
	return 0;
}

/*
 * SFR-CACC algorithm:
 * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
 * execute steps C, D, F.
 *
 * C has been implemented in sctp_outq_sack
 */
static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
				     struct sctp_transport *transport,
				     int count_of_newacks)
{
	if (!primary->cacc.cycling_changeover) {
		if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
			return 1;
		if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
			return 1;
		return 0;
	}
	return 0;
}

/*
 * SFR-CACC algorithm:
 * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
 * than next_tsn_at_change of the current primary, then
 * the sender MUST NOT increment missing report count
 * for t.
 */
static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
{
	if (primary->cacc.cycling_changeover &&
	    TSN_lt(tsn, primary->cacc.next_tsn_at_change))
		return 1;
	return 0;
}

/*
 * SFR-CACC algorithm:
 * 3) If the missing report count for TSN t is to be
 * incremented according to [RFC2960] and
 * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
 * then the sender MUST further execute steps 3.1 and
 * 3.2 to determine if the missing report count for
 * TSN t SHOULD NOT be incremented.
 *
 * 3.3) If 3.1 and 3.2 do not dictate that the missing
 * report count for t should not be incremented, then
 * the sender SHOULD increment missing report count for
 * t (according to [RFC2960] and [SCTP_STEWART_2002]).
 */
static inline int sctp_cacc_skip(struct sctp_transport *primary,
				 struct sctp_transport *transport,
				 int count_of_newacks,
				 __u32 tsn)
{
	if (primary->cacc.changeover_active &&
	    (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
	     sctp_cacc_skip_3_2(primary, tsn)))
		return 1;
	return 0;
}

/* Initialize an existing sctp_outq.  This does the boring stuff.
 * You still need to define handlers if you really want to DO
 * something with this structure...
 */
void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
{
	memset(q, 0, sizeof(struct sctp_outq));

	q->asoc = asoc;
	INIT_LIST_HEAD(&q->out_chunk_list);
	INIT_LIST_HEAD(&q->control_chunk_list);
	INIT_LIST_HEAD(&q->retransmit);
	INIT_LIST_HEAD(&q->sacked);
	INIT_LIST_HEAD(&q->abandoned);
	sctp_sched_set_sched(asoc, sctp_sk(asoc->base.sk)->default_ss);
}

/* Free the outqueue structure and any related pending chunks.
 */
static void __sctp_outq_teardown(struct sctp_outq *q)
{
	struct sctp_transport *transport;
	struct list_head *lchunk, *temp;
	struct sctp_chunk *chunk, *tmp;

	/* Throw away unacknowledged chunks. */
	list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
			transports) {
		while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
			chunk = list_entry(lchunk, struct sctp_chunk,
					   transmitted_list);
			/* Mark as part of a failed message. */
			sctp_chunk_fail(chunk, q->error);
			sctp_chunk_free(chunk);
		}
	}

	/* Throw away chunks that have been gap ACKed.  */
	list_for_each_safe(lchunk, temp, &q->sacked) {
		list_del_init(lchunk);
		chunk = list_entry(lchunk, struct sctp_chunk,
				   transmitted_list);
		sctp_chunk_fail(chunk, q->error);
		sctp_chunk_free(chunk);
	}

	/* Throw away any chunks in the retransmit queue. */
	list_for_each_safe(lchunk, temp, &q->retransmit) {
		list_del_init(lchunk);
		chunk = list_entry(lchunk, struct sctp_chunk,
				   transmitted_list);
		sctp_chunk_fail(chunk, q->error);
		sctp_chunk_free(chunk);
	}

	/* Throw away any chunks that are in the abandoned queue. */
	list_for_each_safe(lchunk, temp, &q->abandoned) {
		list_del_init(lchunk);
		chunk = list_entry(lchunk, struct sctp_chunk,
				   transmitted_list);
		sctp_chunk_fail(chunk, q->error);
		sctp_chunk_free(chunk);
	}

	/* Throw away any leftover data chunks. */
	while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
		sctp_sched_dequeue_done(q, chunk);

		/* Mark as send failure. */
		sctp_chunk_fail(chunk, q->error);
		sctp_chunk_free(chunk);
	}

	/* Throw away any leftover control chunks. */
	list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
		list_del_init(&chunk->list);
		sctp_chunk_free(chunk);
	}
}

void sctp_outq_teardown(struct sctp_outq *q)
{
	__sctp_outq_teardown(q);
	sctp_outq_init(q->asoc, q);
}

/* Free the outqueue structure and any related pending chunks.  */
void sctp_outq_free(struct sctp_outq *q)
{
	/* Throw away leftover chunks. */
	__sctp_outq_teardown(q);
}

/* Put a new chunk in an sctp_outq.  */
void sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk, gfp_t gfp)
{
	struct net *net = q->asoc->base.net;

	pr_debug("%s: outq:%p, chunk:%p[%s]\n", __func__, q, chunk,
		 chunk && chunk->chunk_hdr ?
		 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
		 "illegal chunk");

	/* If it is data, queue it up, otherwise, send it
	 * immediately.
	 */
	if (sctp_chunk_is_data(chunk)) {
		pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
			 __func__, q, chunk, chunk && chunk->chunk_hdr ?
			 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
			 "illegal chunk");

		sctp_outq_tail_data(q, chunk);
		if (chunk->asoc->peer.prsctp_capable &&
		    SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
			chunk->asoc->sent_cnt_removable++;
		if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
			SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
		else
			SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
	} else {
		list_add_tail(&chunk->list, &q->control_chunk_list);
		SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
	}

	if (!q->cork)
		sctp_outq_flush(q, 0, gfp);
}

/* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
 * and the abandoned list are in ascending order.
 */
static void sctp_insert_list(struct list_head *head, struct list_head *new)
{
	struct list_head *pos;
	struct sctp_chunk *nchunk, *lchunk;
	__u32 ntsn, ltsn;
	int done = 0;

	nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
	ntsn = ntohl(nchunk->subh.data_hdr->tsn);

	list_for_each(pos, head) {
		lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
		ltsn = ntohl(lchunk->subh.data_hdr->tsn);
		if (TSN_lt(ntsn, ltsn)) {
			list_add(new, pos->prev);
			done = 1;
			break;
		}
	}
	if (!done)
		list_add_tail(new, head);
}

static int sctp_prsctp_prune_sent(struct sctp_association *asoc,
				  struct sctp_sndrcvinfo *sinfo,
				  struct list_head *queue, int msg_len)
{
	struct sctp_chunk *chk, *temp;

	list_for_each_entry_safe(chk, temp, queue, transmitted_list) {
		struct sctp_stream_out *streamout;

		if (!chk->msg->abandoned &&
		    (!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
		     chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
			continue;

		chk->msg->abandoned = 1;
		list_del_init(&chk->transmitted_list);
		sctp_insert_list(&asoc->outqueue.abandoned,
				 &chk->transmitted_list);

		streamout = SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
		asoc->sent_cnt_removable--;
		asoc->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
		streamout->ext->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;

		if (queue != &asoc->outqueue.retransmit &&
		    !chk->tsn_gap_acked) {
			if (chk->transport)
				chk->transport->flight_size -=
						sctp_data_size(chk);
			asoc->outqueue.outstanding_bytes -= sctp_data_size(chk);
		}

		msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
		if (msg_len <= 0)
			break;
	}

	return msg_len;
}

static int sctp_prsctp_prune_unsent(struct sctp_association *asoc,
				    struct sctp_sndrcvinfo *sinfo, int msg_len)
{
	struct sctp_outq *q = &asoc->outqueue;
	struct sctp_chunk *chk, *temp;

	q->sched->unsched_all(&asoc->stream);

	list_for_each_entry_safe(chk, temp, &q->out_chunk_list, list) {
		if (!chk->msg->abandoned &&
		    (!(chk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG) ||
		     !SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
		     chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
			continue;

		chk->msg->abandoned = 1;
		sctp_sched_dequeue_common(q, chk);
		asoc->sent_cnt_removable--;
		asoc->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
		if (chk->sinfo.sinfo_stream < asoc->stream.outcnt) {
			struct sctp_stream_out *streamout =
				SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);

			streamout->ext->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
		}

		msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
		sctp_chunk_free(chk);
		if (msg_len <= 0)
			break;
	}

	q->sched->sched_all(&asoc->stream);

	return msg_len;
}

/* Abandon the chunks according their priorities */
void sctp_prsctp_prune(struct sctp_association *asoc,
		       struct sctp_sndrcvinfo *sinfo, int msg_len)
{
	struct sctp_transport *transport;

	if (!asoc->peer.prsctp_capable || !asoc->sent_cnt_removable)
		return;

	msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
					 &asoc->outqueue.retransmit,
					 msg_len);
	if (msg_len <= 0)
		return;

	list_for_each_entry(transport, &asoc->peer.transport_addr_list,
			    transports) {
		msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
						 &transport->transmitted,
						 msg_len);
		if (msg_len <= 0)
			return;
	}

	sctp_prsctp_prune_unsent(asoc, sinfo, msg_len);
}

/* Mark all the eligible packets on a transport for retransmission.  */
void sctp_retransmit_mark(struct sctp_outq *q,
			  struct sctp_transport *transport,
			  __u8 reason)
{
	struct list_head *lchunk, *ltemp;
	struct sctp_chunk *chunk;

	/* Walk through the specified transmitted queue.  */
	list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
		chunk = list_entry(lchunk, struct sctp_chunk,
				   transmitted_list);

		/* If the chunk is abandoned, move it to abandoned list. */
		if (sctp_chunk_abandoned(chunk)) {
			list_del_init(lchunk);
			sctp_insert_list(&q->abandoned, lchunk);

			/* If this chunk has not been previousely acked,
			 * stop considering it 'outstanding'.  Our peer
			 * will most likely never see it since it will
			 * not be retransmitted
			 */
			if (!chunk->tsn_gap_acked) {
				if (chunk->transport)
					chunk->transport->flight_size -=
							sctp_data_size(chunk);
				q->outstanding_bytes -= sctp_data_size(chunk);
				q->asoc->peer.rwnd += sctp_data_size(chunk);
			}
			continue;
		}

		/* If we are doing  retransmission due to a timeout or pmtu
		 * discovery, only the  chunks that are not yet acked should
		 * be added to the retransmit queue.
		 */
		if ((reason == SCTP_RTXR_FAST_RTX  &&
			    (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
		    (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
			/* RFC 2960 6.2.1 Processing a Received SACK
			 *
			 * C) Any time a DATA chunk is marked for
			 * retransmission (via either T3-rtx timer expiration
			 * (Section 6.3.3) or via fast retransmit
			 * (Section 7.2.4)), add the data size of those
			 * chunks to the rwnd.
			 */
			q->asoc->peer.rwnd += sctp_data_size(chunk);
			q->outstanding_bytes -= sctp_data_size(chunk);
			if (chunk->transport)
				transport->flight_size -= sctp_data_size(chunk);

			/* sctpimpguide-05 Section 2.8.2
			 * M5) If a T3-rtx timer expires, the
			 * 'TSN.Missing.Report' of all affected TSNs is set
			 * to 0.
			 */
			chunk->tsn_missing_report = 0;

			/* If a chunk that is being used for RTT measurement
			 * has to be retransmitted, we cannot use this chunk
			 * anymore for RTT measurements. Reset rto_pending so
			 * that a new RTT measurement is started when a new
			 * data chunk is sent.
			 */
			if (chunk->rtt_in_progress) {
				chunk->rtt_in_progress = 0;
				transport->rto_pending = 0;
			}

			/* Move the chunk to the retransmit queue. The chunks
			 * on the retransmit queue are always kept in order.
			 */
			list_del_init(lchunk);
			sctp_insert_list(&q->retransmit, lchunk);
		}
	}

	pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, "
		 "flight_size:%d, pba:%d\n", __func__, transport, reason,
		 transport->cwnd, transport->ssthresh, transport->flight_size,
		 transport->partial_bytes_acked);
}

/* Mark all the eligible packets on a transport for retransmission and force
 * one packet out.
 */
void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
		     enum sctp_retransmit_reason reason)
{
	struct net *net = q->asoc->base.net;

	switch (reason) {
	case SCTP_RTXR_T3_RTX:
		SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
		sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
		/* Update the retran path if the T3-rtx timer has expired for
		 * the current retran path.
		 */
		if (transport == transport->asoc->peer.retran_path)
			sctp_assoc_update_retran_path(transport->asoc);
		transport->asoc->rtx_data_chunks +=
			transport->asoc->unack_data;
		break;
	case SCTP_RTXR_FAST_RTX:
		SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
		sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
		q->fast_rtx = 1;
		break;
	case SCTP_RTXR_PMTUD:
		SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
		break;
	case SCTP_RTXR_T1_RTX:
		SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
		transport->asoc->init_retries++;
		break;
	default:
		BUG();
	}

	sctp_retransmit_mark(q, transport, reason);

	/* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
	 * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
	 * following the procedures outlined in C1 - C5.
	 */
	if (reason == SCTP_RTXR_T3_RTX)
		q->asoc->stream.si->generate_ftsn(q, q->asoc->ctsn_ack_point);

	/* Flush the queues only on timeout, since fast_rtx is only
	 * triggered during sack processing and the queue
	 * will be flushed at the end.
	 */
	if (reason != SCTP_RTXR_FAST_RTX)
		sctp_outq_flush(q, /* rtx_timeout */ 1, GFP_ATOMIC);
}

/*
 * Transmit DATA chunks on the retransmit queue.  Upon return from
 * __sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
 * need to be transmitted by the caller.
 * We assume that pkt->transport has already been set.
 *
 * The return value is a normal kernel error return value.
 */
static int __sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
				 int rtx_timeout, int *start_timer, gfp_t gfp)
{
	struct sctp_transport *transport = pkt->transport;
	struct sctp_chunk *chunk, *chunk1;
	struct list_head *lqueue;
	enum sctp_xmit status;
	int error = 0;
	int timer = 0;
	int done = 0;
	int fast_rtx;

	lqueue = &q->retransmit;
	fast_rtx = q->fast_rtx;

	/* This loop handles time-out retransmissions, fast retransmissions,
	 * and retransmissions due to opening of whindow.
	 *
	 * RFC 2960 6.3.3 Handle T3-rtx Expiration
	 *
	 * E3) Determine how many of the earliest (i.e., lowest TSN)
	 * outstanding DATA chunks for the address for which the
	 * T3-rtx has expired will fit into a single packet, subject
	 * to the MTU constraint for the path corresponding to the
	 * destination transport address to which the retransmission
	 * is being sent (this may be different from the address for
	 * which the timer expires [see Section 6.4]). Call this value
	 * K. Bundle and retransmit those K DATA chunks in a single
	 * packet to the destination endpoint.
	 *
	 * [Just to be painfully clear, if we are retransmitting
	 * because a timeout just happened, we should send only ONE
	 * packet of retransmitted data.]
	 *
	 * For fast retransmissions we also send only ONE packet.  However,
	 * if we are just flushing the queue due to open window, we'll
	 * try to send as much as possible.
	 */
	list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
		/* If the chunk is abandoned, move it to abandoned list. */
		if (sctp_chunk_abandoned(chunk)) {
			list_del_init(&chunk->transmitted_list);
			sctp_insert_list(&q->abandoned,
					 &chunk->transmitted_list);
			continue;
		}

		/* Make sure that Gap Acked TSNs are not retransmitted.  A
		 * simple approach is just to move such TSNs out of the
		 * way and into a 'transmitted' queue and skip to the
		 * next chunk.
		 */
		if (chunk->tsn_gap_acked) {
			list_move_tail(&chunk->transmitted_list,
				       &transport->transmitted);
			continue;
		}

		/* If we are doing fast retransmit, ignore non-fast_rtransmit
		 * chunks
		 */
		if (fast_rtx && !chunk->fast_retransmit)
			continue;

redo:
		/* Attempt to append this chunk to the packet. */
		status = sctp_packet_append_chunk(pkt, chunk);

		switch (status) {
		case SCTP_XMIT_PMTU_FULL:
			if (!pkt->has_data && !pkt->has_cookie_echo) {
				/* If this packet did not contain DATA then
				 * retransmission did not happen, so do it
				 * again.  We'll ignore the error here since
				 * control chunks are already freed so there
				 * is nothing we can do.
				 */
				sctp_packet_transmit(pkt, gfp);
				goto redo;
			}

			/* Send this packet.  */
			error = sctp_packet_transmit(pkt, gfp);

			/* If we are retransmitting, we should only
			 * send a single packet.
			 * Otherwise, try appending this chunk again.
			 */
			if (rtx_timeout || fast_rtx)
				done = 1;
			else
				goto redo;

			/* Bundle next chunk in the next round.  */
			break;

		case SCTP_XMIT_RWND_FULL:
			/* Send this packet. */
			error = sctp_packet_transmit(pkt, gfp);

			/* Stop sending DATA as there is no more room
			 * at the receiver.
			 */
			done = 1;
			break;

		case SCTP_XMIT_DELAY:
			/* Send this packet. */
			error = sctp_packet_transmit(pkt, gfp);

			/* Stop sending DATA because of nagle delay. */
			done = 1;
			break;

		default:
			/* The append was successful, so add this chunk to
			 * the transmitted list.
			 */
			list_move_tail(&chunk->transmitted_list,
				       &transport->transmitted);

			/* Mark the chunk as ineligible for fast retransmit
			 * after it is retransmitted.
			 */
			if (chunk->fast_retransmit == SCTP_NEED_FRTX)
				chunk->fast_retransmit = SCTP_DONT_FRTX;

			q->asoc->stats.rtxchunks++;
			break;
		}

		/* Set the timer if there were no errors */
		if (!error && !timer)
			timer = 1;

		if (done)
			break;
	}

	/* If we are here due to a retransmit timeout or a fast
	 * retransmit and if there are any chunks left in the retransmit
	 * queue that could not fit in the PMTU sized packet, they need
	 * to be marked as ineligible for a subsequent fast retransmit.
	 */
	if (rtx_timeout || fast_rtx) {
		list_for_each_entry(chunk1, lqueue, transmitted_list) {
			if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
				chunk1->fast_retransmit = SCTP_DONT_FRTX;
		}
	}

	*start_timer = timer;

	/* Clear fast retransmit hint */
	if (fast_rtx)
		q->fast_rtx = 0;

	return error;
}

/* Cork the outqueue so queued chunks are really queued. */
void sctp_outq_uncork(struct sctp_outq *q, gfp_t gfp)
{
	if (q->cork)
		q->cork = 0;

	sctp_outq_flush(q, 0, gfp);
}

static int sctp_packet_singleton(struct sctp_transport *transport,
				 struct sctp_chunk *chunk, gfp_t gfp)
{
	const struct sctp_association *asoc = transport->asoc;
	const __u16 sport = asoc->base.bind_addr.port;
	const __u16 dport = asoc->peer.port;
	const __u32 vtag = asoc->peer.i.init_tag;
	struct sctp_packet singleton;

	sctp_packet_init(&singleton, transport, sport, dport);
	sctp_packet_config(&singleton, vtag, 0);
	sctp_packet_append_chunk(&singleton, chunk);
	return sctp_packet_transmit(&singleton, gfp);
}

/* Struct to hold the context during sctp outq flush */
struct sctp_flush_ctx {
	struct sctp_outq *q;
	/* Current transport being used. It's NOT the same as curr active one */
	struct sctp_transport *transport;
	/* These transports have chunks to send. */
	struct list_head transport_list;
	struct sctp_association *asoc;
	/* Packet on the current transport above */
	struct sctp_packet *packet;
	gfp_t gfp;
};

/* transport: current transport */
static void sctp_outq_select_transport(struct sctp_flush_ctx *ctx,
				       struct sctp_chunk *chunk)
{
	struct sctp_transport *new_transport = chunk->transport;

	if (!new_transport) {
		if (!sctp_chunk_is_data(chunk)) {
			/* If we have a prior transport pointer, see if
			 * the destination address of the chunk
			 * matches the destination address of the
			 * current transport.  If not a match, then
			 * try to look up the transport with a given
			 * destination address.  We do this because
			 * after processing ASCONFs, we may have new
			 * transports created.
			 */
			if (ctx->transport && sctp_cmp_addr_exact(&chunk->dest,
							&ctx->transport->ipaddr))
				new_transport = ctx->transport;
			else
				new_transport = sctp_assoc_lookup_paddr(ctx->asoc,
								  &chunk->dest);
		}

		/* if we still don't have a new transport, then
		 * use the current active path.
		 */
		if (!new_transport)
			new_transport = ctx->asoc->peer.active_path;
	} else {
		__u8 type;

		switch (new_transport->state) {
		case SCTP_INACTIVE:
		case SCTP_UNCONFIRMED:
		case SCTP_PF:
			/* If the chunk is Heartbeat or Heartbeat Ack,
			 * send it to chunk->transport, even if it's
			 * inactive.
			 *
			 * 3.3.6 Heartbeat Acknowledgement:
			 * ...
			 * A HEARTBEAT ACK is always sent to the source IP
			 * address of the IP datagram containing the
			 * HEARTBEAT chunk to which this ack is responding.
			 * ...
			 *
			 * ASCONF_ACKs also must be sent to the source.
			 */
			type = chunk->chunk_hdr->type;
			if (type != SCTP_CID_HEARTBEAT &&
			    type != SCTP_CID_HEARTBEAT_ACK &&
			    type != SCTP_CID_ASCONF_ACK)
				new_transport = ctx->asoc->peer.active_path;
			break;
		default:
			break;
		}
	}

	/* Are we switching transports? Take care of transport locks. */
	if (new_transport != ctx->transport) {
		ctx->transport = new_transport;
		ctx->packet = &ctx->transport->packet;

		if (list_empty(&ctx->transport->send_ready))
			list_add_tail(&ctx->transport->send_ready,
				      &ctx->transport_list);

		sctp_packet_config(ctx->packet,
				   ctx->asoc->peer.i.init_tag,
				   ctx->asoc->peer.ecn_capable);
		/* We've switched transports, so apply the
		 * Burst limit to the new transport.
		 */
		sctp_transport_burst_limited(ctx->transport);
	}
}

static void sctp_outq_flush_ctrl(struct sctp_flush_ctx *ctx)
{
	struct sctp_chunk *chunk, *tmp;
	enum sctp_xmit status;
	int one_packet, error;

	list_for_each_entry_safe(chunk, tmp, &ctx->q->control_chunk_list, list) {
		one_packet = 0;

		/* RFC 5061, 5.3
		 * F1) This means that until such time as the ASCONF
		 * containing the add is acknowledged, the sender MUST
		 * NOT use the new IP address as a source for ANY SCTP
		 * packet except on carrying an ASCONF Chunk.
		 */
		if (ctx->asoc->src_out_of_asoc_ok &&
		    chunk->chunk_hdr->type != SCTP_CID_ASCONF)
			continue;

		list_del_init(&chunk->list);

		/* Pick the right transport to use. Should always be true for
		 * the first chunk as we don't have a transport by then.
		 */
		sctp_outq_select_transport(ctx, chunk);

		switch (chunk->chunk_hdr->type) {
		/* 6.10 Bundling
		 *   ...
		 *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
		 *   COMPLETE with any other chunks.  [Send them immediately.]
		 */
		case SCTP_CID_INIT:
		case SCTP_CID_INIT_ACK:
		case SCTP_CID_SHUTDOWN_COMPLETE:
			error = sctp_packet_singleton(ctx->transport, chunk,
						      ctx->gfp);
			if (error < 0) {
				ctx->asoc->base.sk->sk_err = -error;
				return;
			}
			break;

		case SCTP_CID_ABORT:
			if (sctp_test_T_bit(chunk))
				ctx->packet->vtag = ctx->asoc->c.my_vtag;
			fallthrough;

		/* The following chunks are "response" chunks, i.e.
		 * they are generated in response to something we
		 * received.  If we are sending these, then we can
		 * send only 1 packet containing these chunks.
		 */
		case SCTP_CID_HEARTBEAT_ACK:
		case SCTP_CID_SHUTDOWN_ACK:
		case SCTP_CID_COOKIE_ACK:
		case SCTP_CID_COOKIE_ECHO:
		case SCTP_CID_ERROR:
		case SCTP_CID_ECN_CWR:
		case SCTP_CID_ASCONF_ACK:
			one_packet = 1;
			fallthrough;

		case SCTP_CID_SACK:
		case SCTP_CID_HEARTBEAT:
		case SCTP_CID_SHUTDOWN:
		case SCTP_CID_ECN_ECNE:
		case SCTP_CID_ASCONF:
		case SCTP_CID_FWD_TSN:
		case SCTP_CID_I_FWD_TSN:
		case SCTP_CID_RECONF:
			status = sctp_packet_transmit_chunk(ctx->packet, chunk,
							    one_packet, ctx->gfp);
			if (status != SCTP_XMIT_OK) {
				/* put the chunk back */
				list_add(&chunk->list, &ctx->q->control_chunk_list);
				break;
			}

			ctx->asoc->stats.octrlchunks++;
			/* PR-SCTP C5) If a FORWARD TSN is sent, the
			 * sender MUST assure that at least one T3-rtx
			 * timer is running.
			 */
			if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN ||
			    chunk->chunk_hdr->type == SCTP_CID_I_FWD_TSN) {
				sctp_transport_reset_t3_rtx(ctx->transport);
				ctx->transport->last_time_sent = jiffies;
			}

			if (chunk == ctx->asoc->strreset_chunk)
				sctp_transport_reset_reconf_timer(ctx->transport);

			break;

		default:
			/* We built a chunk with an illegal type! */
			BUG();
		}
	}
}

/* Returns false if new data shouldn't be sent */
static bool sctp_outq_flush_rtx(struct sctp_flush_ctx *ctx,
				int rtx_timeout)
{
	int error, start_timer = 0;

	if (ctx->asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
		return false;

	if (ctx->transport != ctx->asoc->peer.retran_path) {
		/* Switch transports & prepare the packet.  */
		ctx->transport = ctx->asoc->peer.retran_path;
		ctx->packet = &ctx->transport->packet;

		if (list_empty(&ctx->transport->send_ready))
			list_add_tail(&ctx->transport->send_ready,
				      &ctx->transport_list);

		sctp_packet_config(ctx->packet, ctx->asoc->peer.i.init_tag,
				   ctx->asoc->peer.ecn_capable);
	}

	error = __sctp_outq_flush_rtx(ctx->q, ctx->packet, rtx_timeout,
				      &start_timer, ctx->gfp);
	if (error < 0)
		ctx->asoc->base.sk->sk_err = -error;

	if (start_timer) {
		sctp_transport_reset_t3_rtx(ctx->transport);
		ctx->transport->last_time_sent = jiffies;
	}

	/* This can happen on COOKIE-ECHO resend.  Only
	 * one chunk can get bundled with a COOKIE-ECHO.
	 */
	if (ctx->packet->has_cookie_echo)
		return false;

	/* Don't send new data if there is still data
	 * waiting to retransmit.
	 */
	if (!list_empty(&ctx->q->retransmit))
		return false;

	return true;
}

static void sctp_outq_flush_data(struct sctp_flush_ctx *ctx,
				 int rtx_timeout)
{
	struct sctp_chunk *chunk;
	enum sctp_xmit status;

	/* Is it OK to send data chunks?  */
	switch (ctx->asoc->state) {
	case SCTP_STATE_COOKIE_ECHOED:
		/* Only allow bundling when this packet has a COOKIE-ECHO
		 * chunk.
		 */
		if (!ctx->packet || !ctx->packet->has_cookie_echo)
			return;

		fallthrough;
	case SCTP_STATE_ESTABLISHED:
	case SCTP_STATE_SHUTDOWN_PENDING:
	case SCTP_STATE_SHUTDOWN_RECEIVED:
		break;

	default:
		/* Do nothing. */
		return;
	}

	/* RFC 2960 6.1  Transmission of DATA Chunks
	 *
	 * C) When the time comes for the sender to transmit,
	 * before sending new DATA chunks, the sender MUST
	 * first transmit any outstanding DATA chunks which
	 * are marked for retransmission (limited by the
	 * current cwnd).
	 */
	if (!list_empty(&ctx->q->retransmit) &&
	    !sctp_outq_flush_rtx(ctx, rtx_timeout))
		return;

	/* Apply Max.Burst limitation to the current transport in
	 * case it will be used for new data.  We are going to
	 * rest it before we return, but we want to apply the limit
	 * to the currently queued data.
	 */
	if (ctx->transport)
		sctp_transport_burst_limited(ctx->transport);

	/* Finally, transmit new packets.  */
	while ((chunk = sctp_outq_dequeue_data(ctx->q)) != NULL) {
		__u32 sid = ntohs(chunk->subh.data_hdr->stream);
		__u8 stream_state = SCTP_SO(&ctx->asoc->stream, sid)->state;

		/* Has this chunk expired? */
		if (sctp_chunk_abandoned(chunk)) {
			sctp_sched_dequeue_done(ctx->q, chunk);
			sctp_chunk_fail(chunk, 0);
			sctp_chunk_free(chunk);
			continue;
		}

		if (stream_state == SCTP_STREAM_CLOSED) {
			sctp_outq_head_data(ctx->q, chunk);
			break;
		}

		sctp_outq_select_transport(ctx, chunk);

		pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p skb->users:%d\n",
			 __func__, ctx->q, chunk, chunk && chunk->chunk_hdr ?
			 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
			 "illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
			 chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
			 refcount_read(&chunk->skb->users) : -1);

		/* Add the chunk to the packet.  */
		status = sctp_packet_transmit_chunk(ctx->packet, chunk, 0,
						    ctx->gfp);
		if (status != SCTP_XMIT_OK) {
			/* We could not append this chunk, so put
			 * the chunk back on the output queue.
			 */
			pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
				 __func__, ntohl(chunk->subh.data_hdr->tsn),
				 status);

			sctp_outq_head_data(ctx->q, chunk);
			break;
		}

		/* The sender is in the SHUTDOWN-PENDING state,
		 * The sender MAY set the I-bit in the DATA
		 * chunk header.
		 */
		if (ctx->asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
			chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
		if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
			ctx->asoc->stats.ouodchunks++;
		else
			ctx->asoc->stats.oodchunks++;

		/* Only now it's safe to consider this
		 * chunk as sent, sched-wise.
		 */
		sctp_sched_dequeue_done(ctx->q, chunk);

		list_add_tail(&chunk->transmitted_list,
			      &ctx->transport->transmitted);

		sctp_transport_reset_t3_rtx(ctx->transport);
		ctx->transport->last_time_sent = jiffies;

		/* Only let one DATA chunk get bundled with a
		 * COOKIE-ECHO chunk.
		 */
		if (ctx->packet->has_cookie_echo)
			break;
	}
}

static void sctp_outq_flush_transports(struct sctp_flush_ctx *ctx)
{
	struct sock *sk = ctx->asoc->base.sk;
	struct list_head *ltransport;
	struct sctp_packet *packet;
	struct sctp_transport *t;
	int error = 0;

	while ((ltransport = sctp_list_dequeue(&ctx->transport_list)) != NULL) {
		t = list_entry(ltransport, struct sctp_transport, send_ready);
		packet = &t->packet;
		if (!sctp_packet_empty(packet)) {
			rcu_read_lock();
			if (t->dst && __sk_dst_get(sk) != t->dst) {
				dst_hold(t->dst);
				sk_setup_caps(sk, t->dst);
			}
			rcu_read_unlock();
			error = sctp_packet_transmit(packet, ctx->gfp);
			if (error < 0)
				ctx->q->asoc->base.sk->sk_err = -error;
		}

		/* Clear the burst limited state, if any */
		sctp_transport_burst_reset(t);
	}
}

/* Try to flush an outqueue.
 *
 * Description: Send everything in q which we legally can, subject to
 * congestion limitations.
 * * Note: This function can be called from multiple contexts so appropriate
 * locking concerns must be made.  Today we use the sock lock to protect
 * this function.
 */

static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
{
	struct sctp_flush_ctx ctx = {
		.q = q,
		.transport = NULL,
		.transport_list = LIST_HEAD_INIT(ctx.transport_list),
		.asoc = q->asoc,
		.packet = NULL,
		.gfp = gfp,
	};

	/* 6.10 Bundling
	 *   ...
	 *   When bundling control chunks with DATA chunks, an
	 *   endpoint MUST place control chunks first in the outbound
	 *   SCTP packet.  The transmitter MUST transmit DATA chunks
	 *   within a SCTP packet in increasing order of TSN.
	 *   ...
	 */

	sctp_outq_flush_ctrl(&ctx);

	if (q->asoc->src_out_of_asoc_ok)
		goto sctp_flush_out;

	sctp_outq_flush_data(&ctx, rtx_timeout);

sctp_flush_out:

	sctp_outq_flush_transports(&ctx);
}

/* Update unack_data based on the incoming SACK chunk */
static void sctp_sack_update_unack_data(struct sctp_association *assoc,
					struct sctp_sackhdr *sack)
{
	union sctp_sack_variable *frags;
	__u16 unack_data;
	int i;

	unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;

	frags = sack->variable;
	for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
		unack_data -= ((ntohs(frags[i].gab.end) -
				ntohs(frags[i].gab.start) + 1));
	}

	assoc->unack_data = unack_data;
}

/* This is where we REALLY process a SACK.
 *
 * Process the SACK against the outqueue.  Mostly, this just frees
 * things off the transmitted queue.
 */
int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
{
	struct sctp_association *asoc = q->asoc;
	struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
	struct sctp_transport *transport;
	struct sctp_chunk *tchunk = NULL;
	struct list_head *lchunk, *transport_list, *temp;
	union sctp_sack_variable *frags = sack->variable;
	__u32 sack_ctsn, ctsn, tsn;
	__u32 highest_tsn, highest_new_tsn;
	__u32 sack_a_rwnd;
	unsigned int outstanding;
	struct sctp_transport *primary = asoc->peer.primary_path;
	int count_of_newacks = 0;
	int gap_ack_blocks;
	u8 accum_moved = 0;

	/* Grab the association's destination address list. */
	transport_list = &asoc->peer.transport_addr_list;

	/* SCTP path tracepoint for congestion control debugging. */
	if (trace_sctp_probe_path_enabled()) {
		list_for_each_entry(transport, transport_list, transports)
			trace_sctp_probe_path(transport, asoc);
	}

	sack_ctsn = ntohl(sack->cum_tsn_ack);
	gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
	asoc->stats.gapcnt += gap_ack_blocks;
	/*
	 * SFR-CACC algorithm:
	 * On receipt of a SACK the sender SHOULD execute the
	 * following statements.
	 *
	 * 1) If the cumulative ack in the SACK passes next tsn_at_change
	 * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
	 * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
	 * all destinations.
	 * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
	 * is set the receiver of the SACK MUST take the following actions:
	 *
	 * A) Initialize the cacc_saw_newack to 0 for all destination
	 * addresses.
	 *
	 * Only bother if changeover_active is set. Otherwise, this is
	 * totally suboptimal to do on every SACK.
	 */
	if (primary->cacc.changeover_active) {
		u8 clear_cycling = 0;

		if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
			primary->cacc.changeover_active = 0;
			clear_cycling = 1;
		}

		if (clear_cycling || gap_ack_blocks) {
			list_for_each_entry(transport, transport_list,
					transports) {
				if (clear_cycling)
					transport->cacc.cycling_changeover = 0;
				if (gap_ack_blocks)
					transport->cacc.cacc_saw_newack = 0;
			}
		}
	}

	/* Get the highest TSN in the sack. */
	highest_tsn = sack_ctsn;
	if (gap_ack_blocks)
		highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);

	if (TSN_lt(asoc->highest_sacked, highest_tsn))
		asoc->highest_sacked = highest_tsn;

	highest_new_tsn = sack_ctsn;

	/* Run through the retransmit queue.  Credit bytes received
	 * and free those chunks that we can.
	 */
	sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);

	/* Run through the transmitted queue.
	 * Credit bytes received and free those chunks which we can.
	 *
	 * This is a MASSIVE candidate for optimization.
	 */
	list_for_each_entry(transport, transport_list, transports) {
		sctp_check_transmitted(q, &transport->transmitted,
				       transport, &chunk->source, sack,
				       &highest_new_tsn);
		/*
		 * SFR-CACC algorithm:
		 * C) Let count_of_newacks be the number of
		 * destinations for which cacc_saw_newack is set.
		 */
		if (transport->cacc.cacc_saw_newack)
			count_of_newacks++;
	}

	/* Move the Cumulative TSN Ack Point if appropriate.  */
	if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
		asoc->ctsn_ack_point = sack_ctsn;
		accum_moved = 1;
	}

	if (gap_ack_blocks) {

		if (asoc->fast_recovery && accum_moved)
			highest_new_tsn = highest_tsn;

		list_for_each_entry(transport, transport_list, transports)
			sctp_mark_missing(q, &transport->transmitted, transport,
					  highest_new_tsn, count_of_newacks);
	}

	/* Update unack_data field in the assoc. */
	sctp_sack_update_unack_data(asoc, sack);

	ctsn = asoc->ctsn_ack_point;

	/* Throw away stuff rotting on the sack queue.  */
	list_for_each_safe(lchunk, temp, &q->sacked) {
		tchunk = list_entry(lchunk, struct sctp_chunk,
				    transmitted_list);
		tsn = ntohl(tchunk->subh.data_hdr->tsn);
		if (TSN_lte(tsn, ctsn)) {
			list_del_init(&tchunk->transmitted_list);
			if (asoc->peer.prsctp_capable &&
			    SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
				asoc->sent_cnt_removable--;
			sctp_chunk_free(tchunk);
		}
	}

	/* ii) Set rwnd equal to the newly received a_rwnd minus the
	 *     number of bytes still outstanding after processing the
	 *     Cumulative TSN Ack and the Gap Ack Blocks.
	 */

	sack_a_rwnd = ntohl(sack->a_rwnd);
	asoc->peer.zero_window_announced = !sack_a_rwnd;
	outstanding = q->outstanding_bytes;

	if (outstanding < sack_a_rwnd)
		sack_a_rwnd -= outstanding;
	else
		sack_a_rwnd = 0;

	asoc->peer.rwnd = sack_a_rwnd;

	asoc->stream.si->generate_ftsn(q, sack_ctsn);

	pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
	pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
		 "advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
		 asoc->adv_peer_ack_point);

	return sctp_outq_is_empty(q);
}

/* Is the outqueue empty?
 * The queue is empty when we have not pending data, no in-flight data
 * and nothing pending retransmissions.
 */
int sctp_outq_is_empty(const struct sctp_outq *q)
{
	return q->out_qlen == 0 && q->outstanding_bytes == 0 &&
	       list_empty(&q->retransmit);
}

/********************************************************************
 * 2nd Level Abstractions
 ********************************************************************/

/* Go through a transport's transmitted list or the association's retransmit
 * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
 * The retransmit list will not have an associated transport.
 *
 * I added coherent debug information output.	--xguo
 *
 * Instead of printing 'sacked' or 'kept' for each TSN on the
 * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
 * KEPT TSN6-TSN7, etc.
 */
static void sctp_check_transmitted(struct sctp_outq *q,
				   struct list_head *transmitted_queue,
				   struct sctp_transport *transport,
				   union sctp_addr *saddr,
				   struct sctp_sackhdr *sack,
				   __u32 *highest_new_tsn_in_sack)
{
	struct list_head *lchunk;
	struct sctp_chunk *tchunk;
	struct list_head tlist;
	__u32 tsn;
	__u32 sack_ctsn;
	__u32 rtt;
	__u8 restart_timer = 0;
	int bytes_acked = 0;
	int migrate_bytes = 0;
	bool forward_progress = false;

	sack_ctsn = ntohl(sack->cum_tsn_ack);

	INIT_LIST_HEAD(&tlist);

	/* The while loop will skip empty transmitted queues. */
	while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
		tchunk = list_entry(lchunk, struct sctp_chunk,
				    transmitted_list);

		if (sctp_chunk_abandoned(tchunk)) {
			/* Move the chunk to abandoned list. */
			sctp_insert_list(&q->abandoned, lchunk);

			/* If this chunk has not been acked, stop
			 * considering it as 'outstanding'.
			 */
			if (transmitted_queue != &q->retransmit &&
			    !tchunk->tsn_gap_acked) {
				if (tchunk->transport)
					tchunk->transport->flight_size -=
							sctp_data_size(tchunk);
				q->outstanding_bytes -= sctp_data_size(tchunk);
			}
			continue;
		}

		tsn = ntohl(tchunk->subh.data_hdr->tsn);
		if (sctp_acked(sack, tsn)) {
			/* If this queue is the retransmit queue, the
			 * retransmit timer has already reclaimed
			 * the outstanding bytes for this chunk, so only
			 * count bytes associated with a transport.
			 */
			if (transport && !tchunk->tsn_gap_acked) {
				/* If this chunk is being used for RTT
				 * measurement, calculate the RTT and update
				 * the RTO using this value.
				 *
				 * 6.3.1 C5) Karn's algorithm: RTT measurements
				 * MUST NOT be made using packets that were
				 * retransmitted (and thus for which it is
				 * ambiguous whether the reply was for the
				 * first instance of the packet or a later
				 * instance).
				 */
				if (!sctp_chunk_retransmitted(tchunk) &&
				    tchunk->rtt_in_progress) {
					tchunk->rtt_in_progress = 0;
					rtt = jiffies - tchunk->sent_at;
					sctp_transport_update_rto(transport,
								  rtt);
				}

				if (TSN_lte(tsn, sack_ctsn)) {
					/*
					 * SFR-CACC algorithm:
					 * 2) If the SACK contains gap acks
					 * and the flag CHANGEOVER_ACTIVE is
					 * set the receiver of the SACK MUST
					 * take the following action:
					 *
					 * B) For each TSN t being acked that
					 * has not been acked in any SACK so
					 * far, set cacc_saw_newack to 1 for
					 * the destination that the TSN was
					 * sent to.
					 */
					if (sack->num_gap_ack_blocks &&
					    q->asoc->peer.primary_path->cacc.
					    changeover_active)
						transport->cacc.cacc_saw_newack
							= 1;
				}
			}

			/* If the chunk hasn't been marked as ACKED,
			 * mark it and account bytes_acked if the
			 * chunk had a valid transport (it will not
			 * have a transport if ASCONF had deleted it
			 * while DATA was outstanding).
			 */
			if (!tchunk->tsn_gap_acked) {
				tchunk->tsn_gap_acked = 1;
				if (TSN_lt(*highest_new_tsn_in_sack, tsn))
					*highest_new_tsn_in_sack = tsn;
				bytes_acked += sctp_data_size(tchunk);
				if (!tchunk->transport)
					migrate_bytes += sctp_data_size(tchunk);
				forward_progress = true;
			}

			if (TSN_lte(tsn, sack_ctsn)) {
				/* RFC 2960  6.3.2 Retransmission Timer Rules
				 *
				 * R3) Whenever a SACK is received
				 * that acknowledges the DATA chunk
				 * with the earliest outstanding TSN
				 * for that address, restart T3-rtx
				 * timer for that address with its
				 * current RTO.
				 */
				restart_timer = 1;
				forward_progress = true;

				list_add_tail(&tchunk->transmitted_list,
					      &q->sacked);
			} else {
				/* RFC2960 7.2.4, sctpimpguide-05 2.8.2
				 * M2) Each time a SACK arrives reporting
				 * 'Stray DATA chunk(s)' record the highest TSN
				 * reported as newly acknowledged, call this
				 * value 'HighestTSNinSack'. A newly
				 * acknowledged DATA chunk is one not
				 * previously acknowledged in a SACK.
				 *
				 * When the SCTP sender of data receives a SACK
				 * chunk that acknowledges, for the first time,
				 * the receipt of a DATA chunk, all the still
				 * unacknowledged DATA chunks whose TSN is
				 * older than that newly acknowledged DATA
				 * chunk, are qualified as 'Stray DATA chunks'.
				 */
				list_add_tail(lchunk, &tlist);
			}
		} else {
			if (tchunk->tsn_gap_acked) {
				pr_debug("%s: receiver reneged on data TSN:0x%x\n",
					 __func__, tsn);

				tchunk->tsn_gap_acked = 0;

				if (tchunk->transport)
					bytes_acked -= sctp_data_size(tchunk);

				/* RFC 2960 6.3.2 Retransmission Timer Rules
				 *
				 * R4) Whenever a SACK is received missing a
				 * TSN that was previously acknowledged via a
				 * Gap Ack Block, start T3-rtx for the
				 * destination address to which the DATA
				 * chunk was originally
				 * transmitted if it is not already running.
				 */
				restart_timer = 1;
			}

			list_add_tail(lchunk, &tlist);
		}
	}

	if (transport) {
		if (bytes_acked) {
			struct sctp_association *asoc = transport->asoc;

			/* We may have counted DATA that was migrated
			 * to this transport due to DEL-IP operation.
			 * Subtract those bytes, since the were never
			 * send on this transport and shouldn't be
			 * credited to this transport.
			 */
			bytes_acked -= migrate_bytes;

			/* 8.2. When an outstanding TSN is acknowledged,
			 * the endpoint shall clear the error counter of
			 * the destination transport address to which the
			 * DATA chunk was last sent.
			 * The association's overall error counter is
			 * also cleared.
			 */
			transport->error_count = 0;
			transport->asoc->overall_error_count = 0;
			forward_progress = true;

			/*
			 * While in SHUTDOWN PENDING, we may have started
			 * the T5 shutdown guard timer after reaching the
			 * retransmission limit. Stop that timer as soon
			 * as the receiver acknowledged any data.
			 */
			if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
			    del_timer(&asoc->timers
				[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
					sctp_association_put(asoc);

			/* Mark the destination transport address as
			 * active if it is not so marked.
			 */
			if ((transport->state == SCTP_INACTIVE ||
			     transport->state == SCTP_UNCONFIRMED) &&
			    sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
				sctp_assoc_control_transport(
					transport->asoc,
					transport,
					SCTP_TRANSPORT_UP,
					SCTP_RECEIVED_SACK);
			}

			sctp_transport_raise_cwnd(transport, sack_ctsn,
						  bytes_acked);

			transport->flight_size -= bytes_acked;
			if (transport->flight_size == 0)
				transport->partial_bytes_acked = 0;
			q->outstanding_bytes -= bytes_acked + migrate_bytes;
		} else {
			/* RFC 2960 6.1, sctpimpguide-06 2.15.2
			 * When a sender is doing zero window probing, it
			 * should not timeout the association if it continues
			 * to receive new packets from the receiver. The
			 * reason is that the receiver MAY keep its window
			 * closed for an indefinite time.
			 * A sender is doing zero window probing when the
			 * receiver's advertised window is zero, and there is
			 * only one data chunk in flight to the receiver.
			 *
			 * Allow the association to timeout while in SHUTDOWN
			 * PENDING or SHUTDOWN RECEIVED in case the receiver
			 * stays in zero window mode forever.
			 */
			if (!q->asoc->peer.rwnd &&
			    !list_empty(&tlist) &&
			    (sack_ctsn+2 == q->asoc->next_tsn) &&
			    q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
				pr_debug("%s: sack received for zero window "
					 "probe:%u\n", __func__, sack_ctsn);

				q->asoc->overall_error_count = 0;
				transport->error_count = 0;
			}
		}

		/* RFC 2960 6.3.2 Retransmission Timer Rules
		 *
		 * R2) Whenever all outstanding data sent to an address have
		 * been acknowledged, turn off the T3-rtx timer of that
		 * address.
		 */
		if (!transport->flight_size) {
			if (del_timer(&transport->T3_rtx_timer))
				sctp_transport_put(transport);
		} else if (restart_timer) {
			if (!mod_timer(&transport->T3_rtx_timer,
				       jiffies + transport->rto))
				sctp_transport_hold(transport);
		}

		if (forward_progress) {
			if (transport->dst)
				sctp_transport_dst_confirm(transport);
		}
	}

	list_splice(&tlist, transmitted_queue);
}

/* Mark chunks as missing and consequently may get retransmitted. */
static void sctp_mark_missing(struct sctp_outq *q,
			      struct list_head *transmitted_queue,
			      struct sctp_transport *transport,
			      __u32 highest_new_tsn_in_sack,
			      int count_of_newacks)
{
	struct sctp_chunk *chunk;
	__u32 tsn;
	char do_fast_retransmit = 0;
	struct sctp_association *asoc = q->asoc;
	struct sctp_transport *primary = asoc->peer.primary_path;

	list_for_each_entry(chunk, transmitted_queue, transmitted_list) {

		tsn = ntohl(chunk->subh.data_hdr->tsn);

		/* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
		 * 'Unacknowledged TSN's', if the TSN number of an
		 * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
		 * value, increment the 'TSN.Missing.Report' count on that
		 * chunk if it has NOT been fast retransmitted or marked for
		 * fast retransmit already.
		 */
		if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
		    !chunk->tsn_gap_acked &&
		    TSN_lt(tsn, highest_new_tsn_in_sack)) {

			/* SFR-CACC may require us to skip marking
			 * this chunk as missing.
			 */
			if (!transport || !sctp_cacc_skip(primary,
						chunk->transport,
						count_of_newacks, tsn)) {
				chunk->tsn_missing_report++;

				pr_debug("%s: tsn:0x%x missing counter:%d\n",
					 __func__, tsn, chunk->tsn_missing_report);
			}
		}
		/*
		 * M4) If any DATA chunk is found to have a
		 * 'TSN.Missing.Report'
		 * value larger than or equal to 3, mark that chunk for
		 * retransmission and start the fast retransmit procedure.
		 */

		if (chunk->tsn_missing_report >= 3) {
			chunk->fast_retransmit = SCTP_NEED_FRTX;
			do_fast_retransmit = 1;
		}
	}

	if (transport) {
		if (do_fast_retransmit)
			sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);

		pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
			 "flight_size:%d, pba:%d\n",  __func__, transport,
			 transport->cwnd, transport->ssthresh,
			 transport->flight_size, transport->partial_bytes_acked);
	}
}

/* Is the given TSN acked by this packet?  */
static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
{
	__u32 ctsn = ntohl(sack->cum_tsn_ack);
	union sctp_sack_variable *frags;
	__u16 tsn_offset, blocks;
	int i;

	if (TSN_lte(tsn, ctsn))
		goto pass;

	/* 3.3.4 Selective Acknowledgment (SACK) (3):
	 *
	 * Gap Ack Blocks:
	 *  These fields contain the Gap Ack Blocks. They are repeated
	 *  for each Gap Ack Block up to the number of Gap Ack Blocks
	 *  defined in the Number of Gap Ack Blocks field. All DATA
	 *  chunks with TSNs greater than or equal to (Cumulative TSN
	 *  Ack + Gap Ack Block Start) and less than or equal to
	 *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
	 *  Block are assumed to have been received correctly.
	 */

	frags = sack->variable;
	blocks = ntohs(sack->num_gap_ack_blocks);
	tsn_offset = tsn - ctsn;
	for (i = 0; i < blocks; ++i) {
		if (tsn_offset >= ntohs(frags[i].gab.start) &&
		    tsn_offset <= ntohs(frags[i].gab.end))
			goto pass;
	}

	return 0;
pass:
	return 1;
}

static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
				    int nskips, __be16 stream)
{
	int i;

	for (i = 0; i < nskips; i++) {
		if (skiplist[i].stream == stream)
			return i;
	}
	return i;
}

/* Create and add a fwdtsn chunk to the outq's control queue if needed. */
void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
{
	struct sctp_association *asoc = q->asoc;
	struct sctp_chunk *ftsn_chunk = NULL;
	struct sctp_fwdtsn_skip ftsn_skip_arr[10];
	int nskips = 0;
	int skip_pos = 0;
	__u32 tsn;
	struct sctp_chunk *chunk;
	struct list_head *lchunk, *temp;

	if (!asoc->peer.prsctp_capable)
		return;

	/* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
	 * received SACK.
	 *
	 * If (Advanced.Peer.Ack.Point < SackCumAck), then update
	 * Advanced.Peer.Ack.Point to be equal to SackCumAck.
	 */
	if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
		asoc->adv_peer_ack_point = ctsn;

	/* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
	 * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
	 * the chunk next in the out-queue space is marked as "abandoned" as
	 * shown in the following example:
	 *
	 * Assuming that a SACK arrived with the Cumulative TSN ACK 102
	 * and the Advanced.Peer.Ack.Point is updated to this value:
	 *
	 *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
	 *   normal SACK processing           local advancement
	 *                ...                           ...
	 *   Adv.Ack.Pt-> 102 acked                     102 acked
	 *                103 abandoned                 103 abandoned
	 *                104 abandoned     Adv.Ack.P-> 104 abandoned
	 *                105                           105
	 *                106 acked                     106 acked
	 *                ...                           ...
	 *
	 * In this example, the data sender successfully advanced the
	 * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
	 */
	list_for_each_safe(lchunk, temp, &q->abandoned) {
		chunk = list_entry(lchunk, struct sctp_chunk,
					transmitted_list);
		tsn = ntohl(chunk->subh.data_hdr->tsn);

		/* Remove any chunks in the abandoned queue that are acked by
		 * the ctsn.
		 */
		if (TSN_lte(tsn, ctsn)) {
			list_del_init(lchunk);
			sctp_chunk_free(chunk);
		} else {
			if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
				asoc->adv_peer_ack_point = tsn;
				if (chunk->chunk_hdr->flags &
					 SCTP_DATA_UNORDERED)
					continue;
				skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
						nskips,
						chunk->subh.data_hdr->stream);
				ftsn_skip_arr[skip_pos].stream =
					chunk->subh.data_hdr->stream;
				ftsn_skip_arr[skip_pos].ssn =
					 chunk->subh.data_hdr->ssn;
				if (skip_pos == nskips)
					nskips++;
				if (nskips == 10)
					break;
			} else
				break;
		}
	}

	/* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
	 * is greater than the Cumulative TSN ACK carried in the received
	 * SACK, the data sender MUST send the data receiver a FORWARD TSN
	 * chunk containing the latest value of the
	 * "Advanced.Peer.Ack.Point".
	 *
	 * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
	 * list each stream and sequence number in the forwarded TSN. This
	 * information will enable the receiver to easily find any
	 * stranded TSN's waiting on stream reorder queues. Each stream
	 * SHOULD only be reported once; this means that if multiple
	 * abandoned messages occur in the same stream then only the
	 * highest abandoned stream sequence number is reported. If the
	 * total size of the FORWARD TSN does NOT fit in a single MTU then
	 * the sender of the FORWARD TSN SHOULD lower the
	 * Advanced.Peer.Ack.Point to the last TSN that will fit in a
	 * single MTU.
	 */
	if (asoc->adv_peer_ack_point > ctsn)
		ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
					      nskips, &ftsn_skip_arr[0]);

	if (ftsn_chunk) {
		list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
		SCTP_INC_STATS(asoc->base.net, SCTP_MIB_OUTCTRLCHUNKS);
	}
}