Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

   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
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
/*
 * net/tipc/link.c: TIPC link code
 *
 * Copyright (c) 1996-2007, 2012-2016, Ericsson AB
 * Copyright (c) 2004-2007, 2010-2013, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "core.h"
#include "subscr.h"
#include "link.h"
#include "bcast.h"
#include "socket.h"
#include "name_distr.h"
#include "discover.h"
#include "netlink.h"
#include "monitor.h"

#include <linux/pkt_sched.h>

struct tipc_stats {
	u32 sent_pkts;
	u32 recv_pkts;
	u32 sent_states;
	u32 recv_states;
	u32 sent_probes;
	u32 recv_probes;
	u32 sent_nacks;
	u32 recv_nacks;
	u32 sent_acks;
	u32 sent_bundled;
	u32 sent_bundles;
	u32 recv_bundled;
	u32 recv_bundles;
	u32 retransmitted;
	u32 sent_fragmented;
	u32 sent_fragments;
	u32 recv_fragmented;
	u32 recv_fragments;
	u32 link_congs;		/* # port sends blocked by congestion */
	u32 deferred_recv;
	u32 duplicates;
	u32 max_queue_sz;	/* send queue size high water mark */
	u32 accu_queue_sz;	/* used for send queue size profiling */
	u32 queue_sz_counts;	/* used for send queue size profiling */
	u32 msg_length_counts;	/* used for message length profiling */
	u32 msg_lengths_total;	/* used for message length profiling */
	u32 msg_length_profile[7]; /* used for msg. length profiling */
};

/**
 * struct tipc_link - TIPC link data structure
 * @addr: network address of link's peer node
 * @name: link name character string
 * @media_addr: media address to use when sending messages over link
 * @timer: link timer
 * @net: pointer to namespace struct
 * @refcnt: reference counter for permanent references (owner node & timer)
 * @peer_session: link session # being used by peer end of link
 * @peer_bearer_id: bearer id used by link's peer endpoint
 * @bearer_id: local bearer id used by link
 * @tolerance: minimum link continuity loss needed to reset link [in ms]
 * @abort_limit: # of unacknowledged continuity probes needed to reset link
 * @state: current state of link FSM
 * @peer_caps: bitmap describing capabilities of peer node
 * @silent_intv_cnt: # of timer intervals without any reception from peer
 * @proto_msg: template for control messages generated by link
 * @pmsg: convenience pointer to "proto_msg" field
 * @priority: current link priority
 * @net_plane: current link network plane ('A' through 'H')
 * @mon_state: cookie with information needed by link monitor
 * @backlog_limit: backlog queue congestion thresholds (indexed by importance)
 * @exp_msg_count: # of tunnelled messages expected during link changeover
 * @reset_rcv_checkpt: seq # of last acknowledged message at time of link reset
 * @mtu: current maximum packet size for this link
 * @advertised_mtu: advertised own mtu when link is being established
 * @transmitq: queue for sent, non-acked messages
 * @backlogq: queue for messages waiting to be sent
 * @snt_nxt: next sequence number to use for outbound messages
 * @last_retransmitted: sequence number of most recently retransmitted message
 * @stale_count: # of identical retransmit requests made by peer
 * @ackers: # of peers that needs to ack each packet before it can be released
 * @acked: # last packet acked by a certain peer. Used for broadcast.
 * @rcv_nxt: next sequence number to expect for inbound messages
 * @deferred_queue: deferred queue saved OOS b'cast message received from node
 * @unacked_window: # of inbound messages rx'd without ack'ing back to peer
 * @inputq: buffer queue for messages to be delivered upwards
 * @namedq: buffer queue for name table messages to be delivered upwards
 * @next_out: ptr to first unsent outbound message in queue
 * @wakeupq: linked list of wakeup msgs waiting for link congestion to abate
 * @long_msg_seq_no: next identifier to use for outbound fragmented messages
 * @reasm_buf: head of partially reassembled inbound message fragments
 * @bc_rcvr: marks that this is a broadcast receiver link
 * @stats: collects statistics regarding link activity
 */
struct tipc_link {
	u32 addr;
	char name[TIPC_MAX_LINK_NAME];
	struct net *net;

	/* Management and link supervision data */
	u32 peer_session;
	u32 session;
	u32 peer_bearer_id;
	u32 bearer_id;
	u32 tolerance;
	u32 abort_limit;
	u32 state;
	u16 peer_caps;
	bool active;
	u32 silent_intv_cnt;
	char if_name[TIPC_MAX_IF_NAME];
	u32 priority;
	char net_plane;
	struct tipc_mon_state mon_state;
	u16 rst_cnt;

	/* Failover/synch */
	u16 drop_point;
	struct sk_buff *failover_reasm_skb;

	/* Max packet negotiation */
	u16 mtu;
	u16 advertised_mtu;

	/* Sending */
	struct sk_buff_head transmq;
	struct sk_buff_head backlogq;
	struct {
		u16 len;
		u16 limit;
	} backlog[5];
	u16 snd_nxt;
	u16 last_retransm;
	u16 window;
	u32 stale_count;

	/* Reception */
	u16 rcv_nxt;
	u32 rcv_unacked;
	struct sk_buff_head deferdq;
	struct sk_buff_head *inputq;
	struct sk_buff_head *namedq;

	/* Congestion handling */
	struct sk_buff_head wakeupq;

	/* Fragmentation/reassembly */
	struct sk_buff *reasm_buf;

	/* Broadcast */
	u16 ackers;
	u16 acked;
	struct tipc_link *bc_rcvlink;
	struct tipc_link *bc_sndlink;
	unsigned long prev_retr;
	u16 prev_from;
	u16 prev_to;
	u8 nack_state;
	bool bc_peer_is_up;

	/* Statistics */
	struct tipc_stats stats;
};

/*
 * Error message prefixes
 */
static const char *link_co_err = "Link tunneling error, ";
static const char *link_rst_msg = "Resetting link ";

/* Send states for broadcast NACKs
 */
enum {
	BC_NACK_SND_CONDITIONAL,
	BC_NACK_SND_UNCONDITIONAL,
	BC_NACK_SND_SUPPRESS,
};

#define TIPC_BC_RETR_LIMIT 10   /* [ms] */

/*
 * Interval between NACKs when packets arrive out of order
 */
#define TIPC_NACK_INTV (TIPC_MIN_LINK_WIN * 2)

/* Wildcard value for link session numbers. When it is known that
 * peer endpoint is down, any session number must be accepted.
 */
#define ANY_SESSION 0x10000

/* Link FSM states:
 */
enum {
	LINK_ESTABLISHED     = 0xe,
	LINK_ESTABLISHING    = 0xe  << 4,
	LINK_RESET           = 0x1  << 8,
	LINK_RESETTING       = 0x2  << 12,
	LINK_PEER_RESET      = 0xd  << 16,
	LINK_FAILINGOVER     = 0xf  << 20,
	LINK_SYNCHING        = 0xc  << 24
};

/* Link FSM state checking routines
 */
static int link_is_up(struct tipc_link *l)
{
	return l->state & (LINK_ESTABLISHED | LINK_SYNCHING);
}

static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
			       struct sk_buff_head *xmitq);
static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
				      u16 rcvgap, int tolerance, int priority,
				      struct sk_buff_head *xmitq);
static void link_print(struct tipc_link *l, const char *str);
static int tipc_link_build_nack_msg(struct tipc_link *l,
				    struct sk_buff_head *xmitq);
static void tipc_link_build_bc_init_msg(struct tipc_link *l,
					struct sk_buff_head *xmitq);
static bool tipc_link_release_pkts(struct tipc_link *l, u16 to);

/*
 *  Simple non-static link routines (i.e. referenced outside this file)
 */
bool tipc_link_is_up(struct tipc_link *l)
{
	return link_is_up(l);
}

bool tipc_link_peer_is_down(struct tipc_link *l)
{
	return l->state == LINK_PEER_RESET;
}

bool tipc_link_is_reset(struct tipc_link *l)
{
	return l->state & (LINK_RESET | LINK_FAILINGOVER | LINK_ESTABLISHING);
}

bool tipc_link_is_establishing(struct tipc_link *l)
{
	return l->state == LINK_ESTABLISHING;
}

bool tipc_link_is_synching(struct tipc_link *l)
{
	return l->state == LINK_SYNCHING;
}

bool tipc_link_is_failingover(struct tipc_link *l)
{
	return l->state == LINK_FAILINGOVER;
}

bool tipc_link_is_blocked(struct tipc_link *l)
{
	return l->state & (LINK_RESETTING | LINK_PEER_RESET | LINK_FAILINGOVER);
}

static bool link_is_bc_sndlink(struct tipc_link *l)
{
	return !l->bc_sndlink;
}

static bool link_is_bc_rcvlink(struct tipc_link *l)
{
	return ((l->bc_rcvlink == l) && !link_is_bc_sndlink(l));
}

int tipc_link_is_active(struct tipc_link *l)
{
	return l->active;
}

void tipc_link_set_active(struct tipc_link *l, bool active)
{
	l->active = active;
}

u32 tipc_link_id(struct tipc_link *l)
{
	return l->peer_bearer_id << 16 | l->bearer_id;
}

int tipc_link_window(struct tipc_link *l)
{
	return l->window;
}

int tipc_link_prio(struct tipc_link *l)
{
	return l->priority;
}

unsigned long tipc_link_tolerance(struct tipc_link *l)
{
	return l->tolerance;
}

struct sk_buff_head *tipc_link_inputq(struct tipc_link *l)
{
	return l->inputq;
}

char tipc_link_plane(struct tipc_link *l)
{
	return l->net_plane;
}

void tipc_link_add_bc_peer(struct tipc_link *snd_l,
			   struct tipc_link *uc_l,
			   struct sk_buff_head *xmitq)
{
	struct tipc_link *rcv_l = uc_l->bc_rcvlink;

	snd_l->ackers++;
	rcv_l->acked = snd_l->snd_nxt - 1;
	snd_l->state = LINK_ESTABLISHED;
	tipc_link_build_bc_init_msg(uc_l, xmitq);
}

void tipc_link_remove_bc_peer(struct tipc_link *snd_l,
			      struct tipc_link *rcv_l,
			      struct sk_buff_head *xmitq)
{
	u16 ack = snd_l->snd_nxt - 1;

	snd_l->ackers--;
	rcv_l->bc_peer_is_up = true;
	rcv_l->state = LINK_ESTABLISHED;
	tipc_link_bc_ack_rcv(rcv_l, ack, xmitq);
	tipc_link_reset(rcv_l);
	rcv_l->state = LINK_RESET;
	if (!snd_l->ackers) {
		tipc_link_reset(snd_l);
		snd_l->state = LINK_RESET;
		__skb_queue_purge(xmitq);
	}
}

int tipc_link_bc_peers(struct tipc_link *l)
{
	return l->ackers;
}

u16 link_bc_rcv_gap(struct tipc_link *l)
{
	struct sk_buff *skb = skb_peek(&l->deferdq);
	u16 gap = 0;

	if (more(l->snd_nxt, l->rcv_nxt))
		gap = l->snd_nxt - l->rcv_nxt;
	if (skb)
		gap = buf_seqno(skb) - l->rcv_nxt;
	return gap;
}

void tipc_link_set_mtu(struct tipc_link *l, int mtu)
{
	l->mtu = mtu;
}

int tipc_link_mtu(struct tipc_link *l)
{
	return l->mtu;
}

u16 tipc_link_rcv_nxt(struct tipc_link *l)
{
	return l->rcv_nxt;
}

u16 tipc_link_acked(struct tipc_link *l)
{
	return l->acked;
}

char *tipc_link_name(struct tipc_link *l)
{
	return l->name;
}

/**
 * tipc_link_create - create a new link
 * @n: pointer to associated node
 * @if_name: associated interface name
 * @bearer_id: id (index) of associated bearer
 * @tolerance: link tolerance to be used by link
 * @net_plane: network plane (A,B,c..) this link belongs to
 * @mtu: mtu to be advertised by link
 * @priority: priority to be used by link
 * @window: send window to be used by link
 * @session: session to be used by link
 * @ownnode: identity of own node
 * @peer: node id of peer node
 * @peer_caps: bitmap describing peer node capabilities
 * @bc_sndlink: the namespace global link used for broadcast sending
 * @bc_rcvlink: the peer specific link used for broadcast reception
 * @inputq: queue to put messages ready for delivery
 * @namedq: queue to put binding table update messages ready for delivery
 * @link: return value, pointer to put the created link
 *
 * Returns true if link was created, otherwise false
 */
bool tipc_link_create(struct net *net, char *if_name, int bearer_id,
		      int tolerance, char net_plane, u32 mtu, int priority,
		      int window, u32 session, u32 ownnode, u32 peer,
		      u16 peer_caps,
		      struct tipc_link *bc_sndlink,
		      struct tipc_link *bc_rcvlink,
		      struct sk_buff_head *inputq,
		      struct sk_buff_head *namedq,
		      struct tipc_link **link)
{
	struct tipc_link *l;

	l = kzalloc(sizeof(*l), GFP_ATOMIC);
	if (!l)
		return false;
	*link = l;
	l->session = session;

	/* Note: peer i/f name is completed by reset/activate message */
	sprintf(l->name, "%u.%u.%u:%s-%u.%u.%u:unknown",
		tipc_zone(ownnode), tipc_cluster(ownnode), tipc_node(ownnode),
		if_name, tipc_zone(peer), tipc_cluster(peer), tipc_node(peer));
	strcpy(l->if_name, if_name);
	l->addr = peer;
	l->peer_caps = peer_caps;
	l->net = net;
	l->peer_session = ANY_SESSION;
	l->bearer_id = bearer_id;
	l->tolerance = tolerance;
	l->net_plane = net_plane;
	l->advertised_mtu = mtu;
	l->mtu = mtu;
	l->priority = priority;
	tipc_link_set_queue_limits(l, window);
	l->ackers = 1;
	l->bc_sndlink = bc_sndlink;
	l->bc_rcvlink = bc_rcvlink;
	l->inputq = inputq;
	l->namedq = namedq;
	l->state = LINK_RESETTING;
	__skb_queue_head_init(&l->transmq);
	__skb_queue_head_init(&l->backlogq);
	__skb_queue_head_init(&l->deferdq);
	skb_queue_head_init(&l->wakeupq);
	skb_queue_head_init(l->inputq);
	return true;
}

/**
 * tipc_link_bc_create - create new link to be used for broadcast
 * @n: pointer to associated node
 * @mtu: mtu to be used
 * @window: send window to be used
 * @inputq: queue to put messages ready for delivery
 * @namedq: queue to put binding table update messages ready for delivery
 * @link: return value, pointer to put the created link
 *
 * Returns true if link was created, otherwise false
 */
bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer,
			 int mtu, int window, u16 peer_caps,
			 struct sk_buff_head *inputq,
			 struct sk_buff_head *namedq,
			 struct tipc_link *bc_sndlink,
			 struct tipc_link **link)
{
	struct tipc_link *l;

	if (!tipc_link_create(net, "", MAX_BEARERS, 0, 'Z', mtu, 0, window,
			      0, ownnode, peer, peer_caps, bc_sndlink,
			      NULL, inputq, namedq, link))
		return false;

	l = *link;
	strcpy(l->name, tipc_bclink_name);
	tipc_link_reset(l);
	l->state = LINK_RESET;
	l->ackers = 0;
	l->bc_rcvlink = l;

	/* Broadcast send link is always up */
	if (link_is_bc_sndlink(l))
		l->state = LINK_ESTABLISHED;

	return true;
}

/**
 * tipc_link_fsm_evt - link finite state machine
 * @l: pointer to link
 * @evt: state machine event to be processed
 */
int tipc_link_fsm_evt(struct tipc_link *l, int evt)
{
	int rc = 0;

	switch (l->state) {
	case LINK_RESETTING:
		switch (evt) {
		case LINK_PEER_RESET_EVT:
			l->state = LINK_PEER_RESET;
			break;
		case LINK_RESET_EVT:
			l->state = LINK_RESET;
			break;
		case LINK_FAILURE_EVT:
		case LINK_FAILOVER_BEGIN_EVT:
		case LINK_ESTABLISH_EVT:
		case LINK_FAILOVER_END_EVT:
		case LINK_SYNCH_BEGIN_EVT:
		case LINK_SYNCH_END_EVT:
		default:
			goto illegal_evt;
		}
		break;
	case LINK_RESET:
		switch (evt) {
		case LINK_PEER_RESET_EVT:
			l->state = LINK_ESTABLISHING;
			break;
		case LINK_FAILOVER_BEGIN_EVT:
			l->state = LINK_FAILINGOVER;
		case LINK_FAILURE_EVT:
		case LINK_RESET_EVT:
		case LINK_ESTABLISH_EVT:
		case LINK_FAILOVER_END_EVT:
			break;
		case LINK_SYNCH_BEGIN_EVT:
		case LINK_SYNCH_END_EVT:
		default:
			goto illegal_evt;
		}
		break;
	case LINK_PEER_RESET:
		switch (evt) {
		case LINK_RESET_EVT:
			l->state = LINK_ESTABLISHING;
			break;
		case LINK_PEER_RESET_EVT:
		case LINK_ESTABLISH_EVT:
		case LINK_FAILURE_EVT:
			break;
		case LINK_SYNCH_BEGIN_EVT:
		case LINK_SYNCH_END_EVT:
		case LINK_FAILOVER_BEGIN_EVT:
		case LINK_FAILOVER_END_EVT:
		default:
			goto illegal_evt;
		}
		break;
	case LINK_FAILINGOVER:
		switch (evt) {
		case LINK_FAILOVER_END_EVT:
			l->state = LINK_RESET;
			break;
		case LINK_PEER_RESET_EVT:
		case LINK_RESET_EVT:
		case LINK_ESTABLISH_EVT:
		case LINK_FAILURE_EVT:
			break;
		case LINK_FAILOVER_BEGIN_EVT:
		case LINK_SYNCH_BEGIN_EVT:
		case LINK_SYNCH_END_EVT:
		default:
			goto illegal_evt;
		}
		break;
	case LINK_ESTABLISHING:
		switch (evt) {
		case LINK_ESTABLISH_EVT:
			l->state = LINK_ESTABLISHED;
			break;
		case LINK_FAILOVER_BEGIN_EVT:
			l->state = LINK_FAILINGOVER;
			break;
		case LINK_RESET_EVT:
			l->state = LINK_RESET;
			break;
		case LINK_FAILURE_EVT:
		case LINK_PEER_RESET_EVT:
		case LINK_SYNCH_BEGIN_EVT:
		case LINK_FAILOVER_END_EVT:
			break;
		case LINK_SYNCH_END_EVT:
		default:
			goto illegal_evt;
		}
		break;
	case LINK_ESTABLISHED:
		switch (evt) {
		case LINK_PEER_RESET_EVT:
			l->state = LINK_PEER_RESET;
			rc |= TIPC_LINK_DOWN_EVT;
			break;
		case LINK_FAILURE_EVT:
			l->state = LINK_RESETTING;
			rc |= TIPC_LINK_DOWN_EVT;
			break;
		case LINK_RESET_EVT:
			l->state = LINK_RESET;
			break;
		case LINK_ESTABLISH_EVT:
		case LINK_SYNCH_END_EVT:
			break;
		case LINK_SYNCH_BEGIN_EVT:
			l->state = LINK_SYNCHING;
			break;
		case LINK_FAILOVER_BEGIN_EVT:
		case LINK_FAILOVER_END_EVT:
		default:
			goto illegal_evt;
		}
		break;
	case LINK_SYNCHING:
		switch (evt) {
		case LINK_PEER_RESET_EVT:
			l->state = LINK_PEER_RESET;
			rc |= TIPC_LINK_DOWN_EVT;
			break;
		case LINK_FAILURE_EVT:
			l->state = LINK_RESETTING;
			rc |= TIPC_LINK_DOWN_EVT;
			break;
		case LINK_RESET_EVT:
			l->state = LINK_RESET;
			break;
		case LINK_ESTABLISH_EVT:
		case LINK_SYNCH_BEGIN_EVT:
			break;
		case LINK_SYNCH_END_EVT:
			l->state = LINK_ESTABLISHED;
			break;
		case LINK_FAILOVER_BEGIN_EVT:
		case LINK_FAILOVER_END_EVT:
		default:
			goto illegal_evt;
		}
		break;
	default:
		pr_err("Unknown FSM state %x in %s\n", l->state, l->name);
	}
	return rc;
illegal_evt:
	pr_err("Illegal FSM event %x in state %x on link %s\n",
	       evt, l->state, l->name);
	return rc;
}

/* link_profile_stats - update statistical profiling of traffic
 */
static void link_profile_stats(struct tipc_link *l)
{
	struct sk_buff *skb;
	struct tipc_msg *msg;
	int length;

	/* Update counters used in statistical profiling of send traffic */
	l->stats.accu_queue_sz += skb_queue_len(&l->transmq);
	l->stats.queue_sz_counts++;

	skb = skb_peek(&l->transmq);
	if (!skb)
		return;
	msg = buf_msg(skb);
	length = msg_size(msg);

	if (msg_user(msg) == MSG_FRAGMENTER) {
		if (msg_type(msg) != FIRST_FRAGMENT)
			return;
		length = msg_size(msg_get_wrapped(msg));
	}
	l->stats.msg_lengths_total += length;
	l->stats.msg_length_counts++;
	if (length <= 64)
		l->stats.msg_length_profile[0]++;
	else if (length <= 256)
		l->stats.msg_length_profile[1]++;
	else if (length <= 1024)
		l->stats.msg_length_profile[2]++;
	else if (length <= 4096)
		l->stats.msg_length_profile[3]++;
	else if (length <= 16384)
		l->stats.msg_length_profile[4]++;
	else if (length <= 32768)
		l->stats.msg_length_profile[5]++;
	else
		l->stats.msg_length_profile[6]++;
}

/* tipc_link_timeout - perform periodic task as instructed from node timeout
 */
int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
{
	int mtyp = 0;
	int rc = 0;
	bool state = false;
	bool probe = false;
	bool setup = false;
	u16 bc_snt = l->bc_sndlink->snd_nxt - 1;
	u16 bc_acked = l->bc_rcvlink->acked;
	struct tipc_mon_state *mstate = &l->mon_state;

	switch (l->state) {
	case LINK_ESTABLISHED:
	case LINK_SYNCHING:
		mtyp = STATE_MSG;
		link_profile_stats(l);
		tipc_mon_get_state(l->net, l->addr, mstate, l->bearer_id);
		if (mstate->reset || (l->silent_intv_cnt > l->abort_limit))
			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
		state = bc_acked != bc_snt;
		state |= l->bc_rcvlink->rcv_unacked;
		state |= l->rcv_unacked;
		state |= !skb_queue_empty(&l->transmq);
		state |= !skb_queue_empty(&l->deferdq);
		probe = mstate->probing;
		probe |= l->silent_intv_cnt;
		if (probe || mstate->monitoring)
			l->silent_intv_cnt++;
		break;
	case LINK_RESET:
		setup = l->rst_cnt++ <= 4;
		setup |= !(l->rst_cnt % 16);
		mtyp = RESET_MSG;
		break;
	case LINK_ESTABLISHING:
		setup = true;
		mtyp = ACTIVATE_MSG;
		break;
	case LINK_PEER_RESET:
	case LINK_RESETTING:
	case LINK_FAILINGOVER:
		break;
	default:
		break;
	}

	if (state || probe || setup)
		tipc_link_build_proto_msg(l, mtyp, probe, 0, 0, 0, xmitq);

	return rc;
}

/**
 * link_schedule_user - schedule a message sender for wakeup after congestion
 * @link: congested link
 * @list: message that was attempted sent
 * Create pseudo msg to send back to user when congestion abates
 * Does not consume buffer list
 */
static int link_schedule_user(struct tipc_link *link, struct sk_buff_head *list)
{
	struct tipc_msg *msg = buf_msg(skb_peek(list));
	int imp = msg_importance(msg);
	u32 oport = msg_origport(msg);
	u32 addr = tipc_own_addr(link->net);
	struct sk_buff *skb;

	/* This really cannot happen...  */
	if (unlikely(imp > TIPC_CRITICAL_IMPORTANCE)) {
		pr_warn("%s<%s>, send queue full", link_rst_msg, link->name);
		return -ENOBUFS;
	}
	/* Non-blocking sender: */
	if (TIPC_SKB_CB(skb_peek(list))->wakeup_pending)
		return -ELINKCONG;

	/* Create and schedule wakeup pseudo message */
	skb = tipc_msg_create(SOCK_WAKEUP, 0, INT_H_SIZE, 0,
			      addr, addr, oport, 0, 0);
	if (!skb)
		return -ENOBUFS;
	TIPC_SKB_CB(skb)->chain_sz = skb_queue_len(list);
	TIPC_SKB_CB(skb)->chain_imp = imp;
	skb_queue_tail(&link->wakeupq, skb);
	link->stats.link_congs++;
	return -ELINKCONG;
}

/**
 * link_prepare_wakeup - prepare users for wakeup after congestion
 * @link: congested link
 * Move a number of waiting users, as permitted by available space in
 * the send queue, from link wait queue to node wait queue for wakeup
 */
void link_prepare_wakeup(struct tipc_link *l)
{
	int pnd[TIPC_SYSTEM_IMPORTANCE + 1] = {0,};
	int imp, lim;
	struct sk_buff *skb, *tmp;

	skb_queue_walk_safe(&l->wakeupq, skb, tmp) {
		imp = TIPC_SKB_CB(skb)->chain_imp;
		lim = l->backlog[imp].limit;
		pnd[imp] += TIPC_SKB_CB(skb)->chain_sz;
		if ((pnd[imp] + l->backlog[imp].len) >= lim)
			break;
		skb_unlink(skb, &l->wakeupq);
		skb_queue_tail(l->inputq, skb);
	}
}

void tipc_link_reset(struct tipc_link *l)
{
	l->peer_session = ANY_SESSION;
	l->session++;
	l->mtu = l->advertised_mtu;
	__skb_queue_purge(&l->transmq);
	__skb_queue_purge(&l->deferdq);
	skb_queue_splice_init(&l->wakeupq, l->inputq);
	__skb_queue_purge(&l->backlogq);
	l->backlog[TIPC_LOW_IMPORTANCE].len = 0;
	l->backlog[TIPC_MEDIUM_IMPORTANCE].len = 0;
	l->backlog[TIPC_HIGH_IMPORTANCE].len = 0;
	l->backlog[TIPC_CRITICAL_IMPORTANCE].len = 0;
	l->backlog[TIPC_SYSTEM_IMPORTANCE].len = 0;
	kfree_skb(l->reasm_buf);
	kfree_skb(l->failover_reasm_skb);
	l->reasm_buf = NULL;
	l->failover_reasm_skb = NULL;
	l->rcv_unacked = 0;
	l->snd_nxt = 1;
	l->rcv_nxt = 1;
	l->acked = 0;
	l->silent_intv_cnt = 0;
	l->rst_cnt = 0;
	l->stale_count = 0;
	l->bc_peer_is_up = false;
	memset(&l->mon_state, 0, sizeof(l->mon_state));
	tipc_link_reset_stats(l);
}

/**
 * tipc_link_xmit(): enqueue buffer list according to queue situation
 * @link: link to use
 * @list: chain of buffers containing message
 * @xmitq: returned list of packets to be sent by caller
 *
 * Consumes the buffer chain, except when returning -ELINKCONG,
 * since the caller then may want to make more send attempts.
 * Returns 0 if success, or errno: -ELINKCONG, -EMSGSIZE or -ENOBUFS
 * Messages at TIPC_SYSTEM_IMPORTANCE are always accepted
 */
int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
		   struct sk_buff_head *xmitq)
{
	struct tipc_msg *hdr = buf_msg(skb_peek(list));
	unsigned int maxwin = l->window;
	unsigned int i, imp = msg_importance(hdr);
	unsigned int mtu = l->mtu;
	u16 ack = l->rcv_nxt - 1;
	u16 seqno = l->snd_nxt;
	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
	struct sk_buff_head *transmq = &l->transmq;
	struct sk_buff_head *backlogq = &l->backlogq;
	struct sk_buff *skb, *_skb, *bskb;
	int pkt_cnt = skb_queue_len(list);

	/* Match msg importance against this and all higher backlog limits: */
	if (!skb_queue_empty(backlogq)) {
		for (i = imp; i <= TIPC_SYSTEM_IMPORTANCE; i++) {
			if (unlikely(l->backlog[i].len >= l->backlog[i].limit))
				return link_schedule_user(l, list);
		}
	}
	if (unlikely(msg_size(hdr) > mtu)) {
		skb_queue_purge(list);
		return -EMSGSIZE;
	}

	if (pkt_cnt > 1) {
		l->stats.sent_fragmented++;
		l->stats.sent_fragments += pkt_cnt;
	}

	/* Prepare each packet for sending, and add to relevant queue: */
	while (skb_queue_len(list)) {
		skb = skb_peek(list);
		hdr = buf_msg(skb);
		msg_set_seqno(hdr, seqno);
		msg_set_ack(hdr, ack);
		msg_set_bcast_ack(hdr, bc_ack);

		if (likely(skb_queue_len(transmq) < maxwin)) {
			_skb = skb_clone(skb, GFP_ATOMIC);
			if (!_skb) {
				skb_queue_purge(list);
				return -ENOBUFS;
			}
			__skb_dequeue(list);
			__skb_queue_tail(transmq, skb);
			__skb_queue_tail(xmitq, _skb);
			TIPC_SKB_CB(skb)->ackers = l->ackers;
			l->rcv_unacked = 0;
			l->stats.sent_pkts++;
			seqno++;
			continue;
		}
		if (tipc_msg_bundle(skb_peek_tail(backlogq), hdr, mtu)) {
			kfree_skb(__skb_dequeue(list));
			l->stats.sent_bundled++;
			continue;
		}
		if (tipc_msg_make_bundle(&bskb, hdr, mtu, l->addr)) {
			kfree_skb(__skb_dequeue(list));
			__skb_queue_tail(backlogq, bskb);
			l->backlog[msg_importance(buf_msg(bskb))].len++;
			l->stats.sent_bundled++;
			l->stats.sent_bundles++;
			continue;
		}
		l->backlog[imp].len += skb_queue_len(list);
		skb_queue_splice_tail_init(list, backlogq);
	}
	l->snd_nxt = seqno;
	return 0;
}

void tipc_link_advance_backlog(struct tipc_link *l, struct sk_buff_head *xmitq)
{
	struct sk_buff *skb, *_skb;
	struct tipc_msg *hdr;
	u16 seqno = l->snd_nxt;
	u16 ack = l->rcv_nxt - 1;
	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;

	while (skb_queue_len(&l->transmq) < l->window) {
		skb = skb_peek(&l->backlogq);
		if (!skb)
			break;
		_skb = skb_clone(skb, GFP_ATOMIC);
		if (!_skb)
			break;
		__skb_dequeue(&l->backlogq);
		hdr = buf_msg(skb);
		l->backlog[msg_importance(hdr)].len--;
		__skb_queue_tail(&l->transmq, skb);
		__skb_queue_tail(xmitq, _skb);
		TIPC_SKB_CB(skb)->ackers = l->ackers;
		msg_set_seqno(hdr, seqno);
		msg_set_ack(hdr, ack);
		msg_set_bcast_ack(hdr, bc_ack);
		l->rcv_unacked = 0;
		l->stats.sent_pkts++;
		seqno++;
	}
	l->snd_nxt = seqno;
}

static void link_retransmit_failure(struct tipc_link *l, struct sk_buff *skb)
{
	struct tipc_msg *hdr = buf_msg(skb);

	pr_warn("Retransmission failure on link <%s>\n", l->name);
	link_print(l, "Resetting link ");
	pr_info("Failed msg: usr %u, typ %u, len %u, err %u\n",
		msg_user(hdr), msg_type(hdr), msg_size(hdr), msg_errcode(hdr));
	pr_info("sqno %u, prev: %x, src: %x\n",
		msg_seqno(hdr), msg_prevnode(hdr), msg_orignode(hdr));
}

int tipc_link_retrans(struct tipc_link *l, u16 from, u16 to,
		      struct sk_buff_head *xmitq)
{
	struct sk_buff *_skb, *skb = skb_peek(&l->transmq);
	struct tipc_msg *hdr;
	u16 ack = l->rcv_nxt - 1;
	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;

	if (!skb)
		return 0;

	/* Detect repeated retransmit failures on same packet */
	if (likely(l->last_retransm != buf_seqno(skb))) {
		l->last_retransm = buf_seqno(skb);
		l->stale_count = 1;
	} else if (++l->stale_count > 100) {
		link_retransmit_failure(l, skb);
		return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
	}

	/* Move forward to where retransmission should start */
	skb_queue_walk(&l->transmq, skb) {
		if (!less(buf_seqno(skb), from))
			break;
	}

	skb_queue_walk_from(&l->transmq, skb) {
		if (more(buf_seqno(skb), to))
			break;
		hdr = buf_msg(skb);
		_skb = __pskb_copy(skb, MIN_H_SIZE, GFP_ATOMIC);
		if (!_skb)
			return 0;
		hdr = buf_msg(_skb);
		msg_set_ack(hdr, ack);
		msg_set_bcast_ack(hdr, bc_ack);
		_skb->priority = TC_PRIO_CONTROL;
		__skb_queue_tail(xmitq, _skb);
		l->stats.retransmitted++;
	}
	return 0;
}

/* tipc_data_input - deliver data and name distr msgs to upper layer
 *
 * Consumes buffer if message is of right type
 * Node lock must be held
 */
static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
			    struct sk_buff_head *inputq)
{
	switch (msg_user(buf_msg(skb))) {
	case TIPC_LOW_IMPORTANCE:
	case TIPC_MEDIUM_IMPORTANCE:
	case TIPC_HIGH_IMPORTANCE:
	case TIPC_CRITICAL_IMPORTANCE:
	case CONN_MANAGER:
		skb_queue_tail(inputq, skb);
		return true;
	case NAME_DISTRIBUTOR:
		l->bc_rcvlink->state = LINK_ESTABLISHED;
		skb_queue_tail(l->namedq, skb);
		return true;
	case MSG_BUNDLER:
	case TUNNEL_PROTOCOL:
	case MSG_FRAGMENTER:
	case BCAST_PROTOCOL:
		return false;
	default:
		pr_warn("Dropping received illegal msg type\n");
		kfree_skb(skb);
		return false;
	};
}

/* tipc_link_input - process packet that has passed link protocol check
 *
 * Consumes buffer
 */
static int tipc_link_input(struct tipc_link *l, struct sk_buff *skb,
			   struct sk_buff_head *inputq)
{
	struct tipc_msg *hdr = buf_msg(skb);
	struct sk_buff **reasm_skb = &l->reasm_buf;
	struct sk_buff *iskb;
	struct sk_buff_head tmpq;
	int usr = msg_user(hdr);
	int rc = 0;
	int pos = 0;
	int ipos = 0;

	if (unlikely(usr == TUNNEL_PROTOCOL)) {
		if (msg_type(hdr) == SYNCH_MSG) {
			__skb_queue_purge(&l->deferdq);
			goto drop;
		}
		if (!tipc_msg_extract(skb, &iskb, &ipos))
			return rc;
		kfree_skb(skb);
		skb = iskb;
		hdr = buf_msg(skb);
		if (less(msg_seqno(hdr), l->drop_point))
			goto drop;
		if (tipc_data_input(l, skb, inputq))
			return rc;
		usr = msg_user(hdr);
		reasm_skb = &l->failover_reasm_skb;
	}

	if (usr == MSG_BUNDLER) {
		skb_queue_head_init(&tmpq);
		l->stats.recv_bundles++;
		l->stats.recv_bundled += msg_msgcnt(hdr);
		while (tipc_msg_extract(skb, &iskb, &pos))
			tipc_data_input(l, iskb, &tmpq);
		tipc_skb_queue_splice_tail(&tmpq, inputq);
		return 0;
	} else if (usr == MSG_FRAGMENTER) {
		l->stats.recv_fragments++;
		if (tipc_buf_append(reasm_skb, &skb)) {
			l->stats.recv_fragmented++;
			tipc_data_input(l, skb, inputq);
		} else if (!*reasm_skb && !link_is_bc_rcvlink(l)) {
			pr_warn_ratelimited("Unable to build fragment list\n");
			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
		}
		return 0;
	} else if (usr == BCAST_PROTOCOL) {
		tipc_bcast_lock(l->net);
		tipc_link_bc_init_rcv(l->bc_rcvlink, hdr);
		tipc_bcast_unlock(l->net);
	}
drop:
	kfree_skb(skb);
	return 0;
}

static bool tipc_link_release_pkts(struct tipc_link *l, u16 acked)
{
	bool released = false;
	struct sk_buff *skb, *tmp;

	skb_queue_walk_safe(&l->transmq, skb, tmp) {
		if (more(buf_seqno(skb), acked))
			break;
		__skb_unlink(skb, &l->transmq);
		kfree_skb(skb);
		released = true;
	}
	return released;
}

/* tipc_link_build_state_msg: prepare link state message for transmission
 *
 * Note that sending of broadcast ack is coordinated among nodes, to reduce
 * risk of ack storms towards the sender
 */
int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
{
	if (!l)
		return 0;

	/* Broadcast ACK must be sent via a unicast link => defer to caller */
	if (link_is_bc_rcvlink(l)) {
		if (((l->rcv_nxt ^ tipc_own_addr(l->net)) & 0xf) != 0xf)
			return 0;
		l->rcv_unacked = 0;

		/* Use snd_nxt to store peer's snd_nxt in broadcast rcv link */
		l->snd_nxt = l->rcv_nxt;
		return TIPC_LINK_SND_STATE;
	}

	/* Unicast ACK */
	l->rcv_unacked = 0;
	l->stats.sent_acks++;
	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, xmitq);
	return 0;
}

/* tipc_link_build_reset_msg: prepare link RESET or ACTIVATE message
 */
void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
{
	int mtyp = RESET_MSG;
	struct sk_buff *skb;

	if (l->state == LINK_ESTABLISHING)
		mtyp = ACTIVATE_MSG;

	tipc_link_build_proto_msg(l, mtyp, 0, 0, 0, 0, xmitq);

	/* Inform peer that this endpoint is going down if applicable */
	skb = skb_peek_tail(xmitq);
	if (skb && (l->state == LINK_RESET))
		msg_set_peer_stopping(buf_msg(skb), 1);
}

/* tipc_link_build_nack_msg: prepare link nack message for transmission
 * Note that sending of broadcast NACK is coordinated among nodes, to
 * reduce the risk of NACK storms towards the sender
 */
static int tipc_link_build_nack_msg(struct tipc_link *l,
				    struct sk_buff_head *xmitq)
{
	u32 def_cnt = ++l->stats.deferred_recv;
	int match1, match2;

	if (link_is_bc_rcvlink(l)) {
		match1 = def_cnt & 0xf;
		match2 = tipc_own_addr(l->net) & 0xf;
		if (match1 == match2)
			return TIPC_LINK_SND_STATE;
		return 0;
	}

	if ((skb_queue_len(&l->deferdq) == 1) || !(def_cnt % TIPC_NACK_INTV))
		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, xmitq);
	return 0;
}

/* tipc_link_rcv - process TIPC packets/messages arriving from off-node
 * @l: the link that should handle the message
 * @skb: TIPC packet
 * @xmitq: queue to place packets to be sent after this call
 */
int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
		  struct sk_buff_head *xmitq)
{
	struct sk_buff_head *defq = &l->deferdq;
	struct tipc_msg *hdr;
	u16 seqno, rcv_nxt, win_lim;
	int rc = 0;

	do {
		hdr = buf_msg(skb);
		seqno = msg_seqno(hdr);
		rcv_nxt = l->rcv_nxt;
		win_lim = rcv_nxt + TIPC_MAX_LINK_WIN;

		/* Verify and update link state */
		if (unlikely(msg_user(hdr) == LINK_PROTOCOL))
			return tipc_link_proto_rcv(l, skb, xmitq);

		if (unlikely(!link_is_up(l))) {
			if (l->state == LINK_ESTABLISHING)
				rc = TIPC_LINK_UP_EVT;
			goto drop;
		}

		/* Don't send probe at next timeout expiration */
		l->silent_intv_cnt = 0;

		/* Drop if outside receive window */
		if (unlikely(less(seqno, rcv_nxt) || more(seqno, win_lim))) {
			l->stats.duplicates++;
			goto drop;
		}

		/* Forward queues and wake up waiting users */
		if (likely(tipc_link_release_pkts(l, msg_ack(hdr)))) {
			tipc_link_advance_backlog(l, xmitq);
			if (unlikely(!skb_queue_empty(&l->wakeupq)))
				link_prepare_wakeup(l);
		}

		/* Defer delivery if sequence gap */
		if (unlikely(seqno != rcv_nxt)) {
			__tipc_skb_queue_sorted(defq, seqno, skb);
			rc |= tipc_link_build_nack_msg(l, xmitq);
			break;
		}

		/* Deliver packet */
		l->rcv_nxt++;
		l->stats.recv_pkts++;
		if (!tipc_data_input(l, skb, l->inputq))
			rc |= tipc_link_input(l, skb, l->inputq);
		if (unlikely(++l->rcv_unacked >= TIPC_MIN_LINK_WIN))
			rc |= tipc_link_build_state_msg(l, xmitq);
		if (unlikely(rc & ~TIPC_LINK_SND_STATE))
			break;
	} while ((skb = __skb_dequeue(defq)));

	return rc;
drop:
	kfree_skb(skb);
	return rc;
}

static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
				      u16 rcvgap, int tolerance, int priority,
				      struct sk_buff_head *xmitq)
{
	struct tipc_link *bcl = l->bc_rcvlink;
	struct sk_buff *skb;
	struct tipc_msg *hdr;
	struct sk_buff_head *dfq = &l->deferdq;
	bool node_up = link_is_up(bcl);
	struct tipc_mon_state *mstate = &l->mon_state;
	int dlen = 0;
	void *data;

	/* Don't send protocol message during reset or link failover */
	if (tipc_link_is_blocked(l))
		return;

	if (!tipc_link_is_up(l) && (mtyp == STATE_MSG))
		return;

	if (!skb_queue_empty(dfq))
		rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;

	skb = tipc_msg_create(LINK_PROTOCOL, mtyp, INT_H_SIZE,
			      tipc_max_domain_size, l->addr,
			      tipc_own_addr(l->net), 0, 0, 0);
	if (!skb)
		return;

	hdr = buf_msg(skb);
	data = msg_data(hdr);
	msg_set_session(hdr, l->session);
	msg_set_bearer_id(hdr, l->bearer_id);
	msg_set_net_plane(hdr, l->net_plane);
	msg_set_next_sent(hdr, l->snd_nxt);
	msg_set_ack(hdr, l->rcv_nxt - 1);
	msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
	msg_set_bc_ack_invalid(hdr, !node_up);
	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
	msg_set_link_tolerance(hdr, tolerance);
	msg_set_linkprio(hdr, priority);
	msg_set_redundant_link(hdr, node_up);
	msg_set_seq_gap(hdr, 0);
	msg_set_seqno(hdr, l->snd_nxt + U16_MAX / 2);

	if (mtyp == STATE_MSG) {
		msg_set_seq_gap(hdr, rcvgap);
		msg_set_bc_gap(hdr, link_bc_rcv_gap(bcl));
		msg_set_probe(hdr, probe);
		tipc_mon_prep(l->net, data, &dlen, mstate, l->bearer_id);
		msg_set_size(hdr, INT_H_SIZE + dlen);
		skb_trim(skb, INT_H_SIZE + dlen);
		l->stats.sent_states++;
		l->rcv_unacked = 0;
	} else {
		/* RESET_MSG or ACTIVATE_MSG */
		msg_set_max_pkt(hdr, l->advertised_mtu);
		strcpy(data, l->if_name);
		msg_set_size(hdr, INT_H_SIZE + TIPC_MAX_IF_NAME);
		skb_trim(skb, INT_H_SIZE + TIPC_MAX_IF_NAME);
	}
	if (probe)
		l->stats.sent_probes++;
	if (rcvgap)
		l->stats.sent_nacks++;
	skb->priority = TC_PRIO_CONTROL;
	__skb_queue_tail(xmitq, skb);
}

/* tipc_link_tnl_prepare(): prepare and return a list of tunnel packets
 * with contents of the link's transmit and backlog queues.
 */
void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
			   int mtyp, struct sk_buff_head *xmitq)
{
	struct sk_buff *skb, *tnlskb;
	struct tipc_msg *hdr, tnlhdr;
	struct sk_buff_head *queue = &l->transmq;
	struct sk_buff_head tmpxq, tnlq;
	u16 pktlen, pktcnt, seqno = l->snd_nxt;

	if (!tnl)
		return;

	skb_queue_head_init(&tnlq);
	skb_queue_head_init(&tmpxq);

	/* At least one packet required for safe algorithm => add dummy */
	skb = tipc_msg_create(TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
			      BASIC_H_SIZE, 0, l->addr, tipc_own_addr(l->net),
			      0, 0, TIPC_ERR_NO_PORT);
	if (!skb) {
		pr_warn("%sunable to create tunnel packet\n", link_co_err);
		return;
	}
	skb_queue_tail(&tnlq, skb);
	tipc_link_xmit(l, &tnlq, &tmpxq);
	__skb_queue_purge(&tmpxq);

	/* Initialize reusable tunnel packet header */
	tipc_msg_init(tipc_own_addr(l->net), &tnlhdr, TUNNEL_PROTOCOL,
		      mtyp, INT_H_SIZE, l->addr);
	pktcnt = skb_queue_len(&l->transmq) + skb_queue_len(&l->backlogq);
	msg_set_msgcnt(&tnlhdr, pktcnt);
	msg_set_bearer_id(&tnlhdr, l->peer_bearer_id);
tnl:
	/* Wrap each packet into a tunnel packet */
	skb_queue_walk(queue, skb) {
		hdr = buf_msg(skb);
		if (queue == &l->backlogq)
			msg_set_seqno(hdr, seqno++);
		pktlen = msg_size(hdr);
		msg_set_size(&tnlhdr, pktlen + INT_H_SIZE);
		tnlskb = tipc_buf_acquire(pktlen + INT_H_SIZE, GFP_ATOMIC);
		if (!tnlskb) {
			pr_warn("%sunable to send packet\n", link_co_err);
			return;
		}
		skb_copy_to_linear_data(tnlskb, &tnlhdr, INT_H_SIZE);
		skb_copy_to_linear_data_offset(tnlskb, INT_H_SIZE, hdr, pktlen);
		__skb_queue_tail(&tnlq, tnlskb);
	}
	if (queue != &l->backlogq) {
		queue = &l->backlogq;
		goto tnl;
	}

	tipc_link_xmit(tnl, &tnlq, xmitq);

	if (mtyp == FAILOVER_MSG) {
		tnl->drop_point = l->rcv_nxt;
		tnl->failover_reasm_skb = l->reasm_buf;
		l->reasm_buf = NULL;
	}
}

/* tipc_link_proto_rcv(): receive link level protocol message :
 * Note that network plane id propagates through the network, and may
 * change at any time. The node with lowest numerical id determines
 * network plane
 */
static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
			       struct sk_buff_head *xmitq)
{
	struct tipc_msg *hdr = buf_msg(skb);
	u16 rcvgap = 0;
	u16 ack = msg_ack(hdr);
	u16 gap = msg_seq_gap(hdr);
	u16 peers_snd_nxt =  msg_next_sent(hdr);
	u16 peers_tol = msg_link_tolerance(hdr);
	u16 peers_prio = msg_linkprio(hdr);
	u16 rcv_nxt = l->rcv_nxt;
	u16 dlen = msg_data_sz(hdr);
	int mtyp = msg_type(hdr);
	void *data;
	char *if_name;
	int rc = 0;

	if (tipc_link_is_blocked(l) || !xmitq)
		goto exit;

	if (tipc_own_addr(l->net) > msg_prevnode(hdr))
		l->net_plane = msg_net_plane(hdr);

	skb_linearize(skb);
	hdr = buf_msg(skb);
	data = msg_data(hdr);

	switch (mtyp) {
	case RESET_MSG:

		/* Ignore duplicate RESET with old session number */
		if ((less_eq(msg_session(hdr), l->peer_session)) &&
		    (l->peer_session != ANY_SESSION))
			break;
		/* fall thru' */

	case ACTIVATE_MSG:

		/* Complete own link name with peer's interface name */
		if_name =  strrchr(l->name, ':') + 1;
		if (sizeof(l->name) - (if_name - l->name) <= TIPC_MAX_IF_NAME)
			break;
		if (msg_data_sz(hdr) < TIPC_MAX_IF_NAME)
			break;
		strncpy(if_name, data, TIPC_MAX_IF_NAME);

		/* Update own tolerance if peer indicates a non-zero value */
		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL))
			l->tolerance = peers_tol;

		/* Update own priority if peer's priority is higher */
		if (in_range(peers_prio, l->priority + 1, TIPC_MAX_LINK_PRI))
			l->priority = peers_prio;

		/* ACTIVATE_MSG serves as PEER_RESET if link is already down */
		if (msg_peer_stopping(hdr))
			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
		else if ((mtyp == RESET_MSG) || !link_is_up(l))
			rc = tipc_link_fsm_evt(l, LINK_PEER_RESET_EVT);

		/* ACTIVATE_MSG takes up link if it was already locally reset */
		if ((mtyp == ACTIVATE_MSG) && (l->state == LINK_ESTABLISHING))
			rc = TIPC_LINK_UP_EVT;

		l->peer_session = msg_session(hdr);
		l->peer_bearer_id = msg_bearer_id(hdr);
		if (l->mtu > msg_max_pkt(hdr))
			l->mtu = msg_max_pkt(hdr);
		break;

	case STATE_MSG:

		/* Update own tolerance if peer indicates a non-zero value */
		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL))
			l->tolerance = peers_tol;

		/* Update own prio if peer indicates a different value */
		if ((peers_prio != l->priority) &&
		    in_range(peers_prio, 1, TIPC_MAX_LINK_PRI)) {
			l->priority = peers_prio;
			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
		}

		l->silent_intv_cnt = 0;
		l->stats.recv_states++;
		if (msg_probe(hdr))
			l->stats.recv_probes++;

		if (!link_is_up(l)) {
			if (l->state == LINK_ESTABLISHING)
				rc = TIPC_LINK_UP_EVT;
			break;
		}
		tipc_mon_rcv(l->net, data, dlen, l->addr,
			     &l->mon_state, l->bearer_id);

		/* Send NACK if peer has sent pkts we haven't received yet */
		if (more(peers_snd_nxt, rcv_nxt) && !tipc_link_is_synching(l))
			rcvgap = peers_snd_nxt - l->rcv_nxt;
		if (rcvgap || (msg_probe(hdr)))
			tipc_link_build_proto_msg(l, STATE_MSG, 0, rcvgap,
						  0, 0, xmitq);
		tipc_link_release_pkts(l, ack);

		/* If NACK, retransmit will now start at right position */
		if (gap) {
			rc = tipc_link_retrans(l, ack + 1, ack + gap, xmitq);
			l->stats.recv_nacks++;
		}

		tipc_link_advance_backlog(l, xmitq);
		if (unlikely(!skb_queue_empty(&l->wakeupq)))
			link_prepare_wakeup(l);
	}
exit:
	kfree_skb(skb);
	return rc;
}

/* tipc_link_build_bc_proto_msg() - create broadcast protocol message
 */
static bool tipc_link_build_bc_proto_msg(struct tipc_link *l, bool bcast,
					 u16 peers_snd_nxt,
					 struct sk_buff_head *xmitq)
{
	struct sk_buff *skb;
	struct tipc_msg *hdr;
	struct sk_buff *dfrd_skb = skb_peek(&l->deferdq);
	u16 ack = l->rcv_nxt - 1;
	u16 gap_to = peers_snd_nxt - 1;

	skb = tipc_msg_create(BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE,
			      0, l->addr, tipc_own_addr(l->net), 0, 0, 0);
	if (!skb)
		return false;
	hdr = buf_msg(skb);
	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
	msg_set_bcast_ack(hdr, ack);
	msg_set_bcgap_after(hdr, ack);
	if (dfrd_skb)
		gap_to = buf_seqno(dfrd_skb) - 1;
	msg_set_bcgap_to(hdr, gap_to);
	msg_set_non_seq(hdr, bcast);
	__skb_queue_tail(xmitq, skb);
	return true;
}

/* tipc_link_build_bc_init_msg() - synchronize broadcast link endpoints.
 *
 * Give a newly added peer node the sequence number where it should
 * start receiving and acking broadcast packets.
 */
static void tipc_link_build_bc_init_msg(struct tipc_link *l,
					struct sk_buff_head *xmitq)
{
	struct sk_buff_head list;

	__skb_queue_head_init(&list);
	if (!tipc_link_build_bc_proto_msg(l->bc_rcvlink, false, 0, &list))
		return;
	msg_set_bc_ack_invalid(buf_msg(skb_peek(&list)), true);
	tipc_link_xmit(l, &list, xmitq);
}

/* tipc_link_bc_init_rcv - receive initial broadcast synch data from peer
 */
void tipc_link_bc_init_rcv(struct tipc_link *l, struct tipc_msg *hdr)
{
	int mtyp = msg_type(hdr);
	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);

	if (link_is_up(l))
		return;

	if (msg_user(hdr) == BCAST_PROTOCOL) {
		l->rcv_nxt = peers_snd_nxt;
		l->state = LINK_ESTABLISHED;
		return;
	}

	if (l->peer_caps & TIPC_BCAST_SYNCH)
		return;

	if (msg_peer_node_is_up(hdr))
		return;

	/* Compatibility: accept older, less safe initial synch data */
	if ((mtyp == RESET_MSG) || (mtyp == ACTIVATE_MSG))
		l->rcv_nxt = peers_snd_nxt;
}

/* link_bc_retr eval()- check if the indicated range can be retransmitted now
 * - Adjust permitted range if there is overlap with previous retransmission
 */
static bool link_bc_retr_eval(struct tipc_link *l, u16 *from, u16 *to)
{
	unsigned long elapsed = jiffies_to_msecs(jiffies - l->prev_retr);

	if (less(*to, *from))
		return false;

	/* New retransmission request */
	if ((elapsed > TIPC_BC_RETR_LIMIT) ||
	    less(*to, l->prev_from) || more(*from, l->prev_to)) {
		l->prev_from = *from;
		l->prev_to = *to;
		l->prev_retr = jiffies;
		return true;
	}

	/* Inside range of previous retransmit */
	if (!less(*from, l->prev_from) && !more(*to, l->prev_to))
		return false;

	/* Fully or partially outside previous range => exclude overlap */
	if (less(*from, l->prev_from)) {
		*to = l->prev_from - 1;
		l->prev_from = *from;
	}
	if (more(*to, l->prev_to)) {
		*from = l->prev_to + 1;
		l->prev_to = *to;
	}
	l->prev_retr = jiffies;
	return true;
}

/* tipc_link_bc_sync_rcv - update rcv link according to peer's send state
 */
int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
			  struct sk_buff_head *xmitq)
{
	struct tipc_link *snd_l = l->bc_sndlink;
	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
	u16 from = msg_bcast_ack(hdr) + 1;
	u16 to = from + msg_bc_gap(hdr) - 1;
	int rc = 0;

	if (!link_is_up(l))
		return rc;

	if (!msg_peer_node_is_up(hdr))
		return rc;

	/* Open when peer ackowledges our bcast init msg (pkt #1) */
	if (msg_ack(hdr))
		l->bc_peer_is_up = true;

	if (!l->bc_peer_is_up)
		return rc;

	l->stats.recv_nacks++;

	/* Ignore if peers_snd_nxt goes beyond receive window */
	if (more(peers_snd_nxt, l->rcv_nxt + l->window))
		return rc;

	if (link_bc_retr_eval(snd_l, &from, &to))
		rc = tipc_link_retrans(snd_l, from, to, xmitq);

	l->snd_nxt = peers_snd_nxt;
	if (link_bc_rcv_gap(l))
		rc |= TIPC_LINK_SND_STATE;

	/* Return now if sender supports nack via STATE messages */
	if (l->peer_caps & TIPC_BCAST_STATE_NACK)
		return rc;

	/* Otherwise, be backwards compatible */

	if (!more(peers_snd_nxt, l->rcv_nxt)) {
		l->nack_state = BC_NACK_SND_CONDITIONAL;
		return 0;
	}

	/* Don't NACK if one was recently sent or peeked */
	if (l->nack_state == BC_NACK_SND_SUPPRESS) {
		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
		return 0;
	}

	/* Conditionally delay NACK sending until next synch rcv */
	if (l->nack_state == BC_NACK_SND_CONDITIONAL) {
		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
		if ((peers_snd_nxt - l->rcv_nxt) < TIPC_MIN_LINK_WIN)
			return 0;
	}

	/* Send NACK now but suppress next one */
	tipc_link_build_bc_proto_msg(l, true, peers_snd_nxt, xmitq);
	l->nack_state = BC_NACK_SND_SUPPRESS;
	return 0;
}

void tipc_link_bc_ack_rcv(struct tipc_link *l, u16 acked,
			  struct sk_buff_head *xmitq)
{
	struct sk_buff *skb, *tmp;
	struct tipc_link *snd_l = l->bc_sndlink;

	if (!link_is_up(l) || !l->bc_peer_is_up)
		return;

	if (!more(acked, l->acked))
		return;

	/* Skip over packets peer has already acked */
	skb_queue_walk(&snd_l->transmq, skb) {
		if (more(buf_seqno(skb), l->acked))
			break;
	}

	/* Update/release the packets peer is acking now */
	skb_queue_walk_from_safe(&snd_l->transmq, skb, tmp) {
		if (more(buf_seqno(skb), acked))
			break;
		if (!--TIPC_SKB_CB(skb)->ackers) {
			__skb_unlink(skb, &snd_l->transmq);
			kfree_skb(skb);
		}
	}
	l->acked = acked;
	tipc_link_advance_backlog(snd_l, xmitq);
	if (unlikely(!skb_queue_empty(&snd_l->wakeupq)))
		link_prepare_wakeup(snd_l);
}

/* tipc_link_bc_nack_rcv(): receive broadcast nack message
 * This function is here for backwards compatibility, since
 * no BCAST_PROTOCOL/STATE messages occur from TIPC v2.5.
 */
int tipc_link_bc_nack_rcv(struct tipc_link *l, struct sk_buff *skb,
			  struct sk_buff_head *xmitq)
{
	struct tipc_msg *hdr = buf_msg(skb);
	u32 dnode = msg_destnode(hdr);
	int mtyp = msg_type(hdr);
	u16 acked = msg_bcast_ack(hdr);
	u16 from = acked + 1;
	u16 to = msg_bcgap_to(hdr);
	u16 peers_snd_nxt = to + 1;
	int rc = 0;

	kfree_skb(skb);

	if (!tipc_link_is_up(l) || !l->bc_peer_is_up)
		return 0;

	if (mtyp != STATE_MSG)
		return 0;

	if (dnode == tipc_own_addr(l->net)) {
		tipc_link_bc_ack_rcv(l, acked, xmitq);
		rc = tipc_link_retrans(l->bc_sndlink, from, to, xmitq);
		l->stats.recv_nacks++;
		return rc;
	}

	/* Msg for other node => suppress own NACK at next sync if applicable */
	if (more(peers_snd_nxt, l->rcv_nxt) && !less(l->rcv_nxt, from))
		l->nack_state = BC_NACK_SND_SUPPRESS;

	return 0;
}

void tipc_link_set_queue_limits(struct tipc_link *l, u32 win)
{
	int max_bulk = TIPC_MAX_PUBLICATIONS / (l->mtu / ITEM_SIZE);

	l->window = win;
	l->backlog[TIPC_LOW_IMPORTANCE].limit      = max_t(u16, 50, win);
	l->backlog[TIPC_MEDIUM_IMPORTANCE].limit   = max_t(u16, 100, win * 2);
	l->backlog[TIPC_HIGH_IMPORTANCE].limit     = max_t(u16, 150, win * 3);
	l->backlog[TIPC_CRITICAL_IMPORTANCE].limit = max_t(u16, 200, win * 4);
	l->backlog[TIPC_SYSTEM_IMPORTANCE].limit   = max_bulk;
}

/**
 * link_reset_stats - reset link statistics
 * @l: pointer to link
 */
void tipc_link_reset_stats(struct tipc_link *l)
{
	memset(&l->stats, 0, sizeof(l->stats));
}

static void link_print(struct tipc_link *l, const char *str)
{
	struct sk_buff *hskb = skb_peek(&l->transmq);
	u16 head = hskb ? msg_seqno(buf_msg(hskb)) : l->snd_nxt - 1;
	u16 tail = l->snd_nxt - 1;

	pr_info("%s Link <%s> state %x\n", str, l->name, l->state);
	pr_info("XMTQ: %u [%u-%u], BKLGQ: %u, SNDNX: %u, RCVNX: %u\n",
		skb_queue_len(&l->transmq), head, tail,
		skb_queue_len(&l->backlogq), l->snd_nxt, l->rcv_nxt);
}

/* Parse and validate nested (link) properties valid for media, bearer and link
 */
int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[])
{
	int err;

	err = nla_parse_nested(props, TIPC_NLA_PROP_MAX, prop,
			       tipc_nl_prop_policy);
	if (err)
		return err;

	if (props[TIPC_NLA_PROP_PRIO]) {
		u32 prio;

		prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
		if (prio > TIPC_MAX_LINK_PRI)
			return -EINVAL;
	}

	if (props[TIPC_NLA_PROP_TOL]) {
		u32 tol;

		tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
		if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
			return -EINVAL;
	}

	if (props[TIPC_NLA_PROP_WIN]) {
		u32 win;

		win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
		if ((win < TIPC_MIN_LINK_WIN) || (win > TIPC_MAX_LINK_WIN))
			return -EINVAL;
	}

	return 0;
}

static int __tipc_nl_add_stats(struct sk_buff *skb, struct tipc_stats *s)
{
	int i;
	struct nlattr *stats;

	struct nla_map {
		u32 key;
		u32 val;
	};

	struct nla_map map[] = {
		{TIPC_NLA_STATS_RX_INFO, 0},
		{TIPC_NLA_STATS_RX_FRAGMENTS, s->recv_fragments},
		{TIPC_NLA_STATS_RX_FRAGMENTED, s->recv_fragmented},
		{TIPC_NLA_STATS_RX_BUNDLES, s->recv_bundles},
		{TIPC_NLA_STATS_RX_BUNDLED, s->recv_bundled},
		{TIPC_NLA_STATS_TX_INFO, 0},
		{TIPC_NLA_STATS_TX_FRAGMENTS, s->sent_fragments},
		{TIPC_NLA_STATS_TX_FRAGMENTED, s->sent_fragmented},
		{TIPC_NLA_STATS_TX_BUNDLES, s->sent_bundles},
		{TIPC_NLA_STATS_TX_BUNDLED, s->sent_bundled},
		{TIPC_NLA_STATS_MSG_PROF_TOT, (s->msg_length_counts) ?
			s->msg_length_counts : 1},
		{TIPC_NLA_STATS_MSG_LEN_CNT, s->msg_length_counts},
		{TIPC_NLA_STATS_MSG_LEN_TOT, s->msg_lengths_total},
		{TIPC_NLA_STATS_MSG_LEN_P0, s->msg_length_profile[0]},
		{TIPC_NLA_STATS_MSG_LEN_P1, s->msg_length_profile[1]},
		{TIPC_NLA_STATS_MSG_LEN_P2, s->msg_length_profile[2]},
		{TIPC_NLA_STATS_MSG_LEN_P3, s->msg_length_profile[3]},
		{TIPC_NLA_STATS_MSG_LEN_P4, s->msg_length_profile[4]},
		{TIPC_NLA_STATS_MSG_LEN_P5, s->msg_length_profile[5]},
		{TIPC_NLA_STATS_MSG_LEN_P6, s->msg_length_profile[6]},
		{TIPC_NLA_STATS_RX_STATES, s->recv_states},
		{TIPC_NLA_STATS_RX_PROBES, s->recv_probes},
		{TIPC_NLA_STATS_RX_NACKS, s->recv_nacks},
		{TIPC_NLA_STATS_RX_DEFERRED, s->deferred_recv},
		{TIPC_NLA_STATS_TX_STATES, s->sent_states},
		{TIPC_NLA_STATS_TX_PROBES, s->sent_probes},
		{TIPC_NLA_STATS_TX_NACKS, s->sent_nacks},
		{TIPC_NLA_STATS_TX_ACKS, s->sent_acks},
		{TIPC_NLA_STATS_RETRANSMITTED, s->retransmitted},
		{TIPC_NLA_STATS_DUPLICATES, s->duplicates},
		{TIPC_NLA_STATS_LINK_CONGS, s->link_congs},
		{TIPC_NLA_STATS_MAX_QUEUE, s->max_queue_sz},
		{TIPC_NLA_STATS_AVG_QUEUE, s->queue_sz_counts ?
			(s->accu_queue_sz / s->queue_sz_counts) : 0}
	};

	stats = nla_nest_start(skb, TIPC_NLA_LINK_STATS);
	if (!stats)
		return -EMSGSIZE;

	for (i = 0; i <  ARRAY_SIZE(map); i++)
		if (nla_put_u32(skb, map[i].key, map[i].val))
			goto msg_full;

	nla_nest_end(skb, stats);

	return 0;
msg_full:
	nla_nest_cancel(skb, stats);

	return -EMSGSIZE;
}

/* Caller should hold appropriate locks to protect the link */
int __tipc_nl_add_link(struct net *net, struct tipc_nl_msg *msg,
		       struct tipc_link *link, int nlflags)
{
	int err;
	void *hdr;
	struct nlattr *attrs;
	struct nlattr *prop;
	struct tipc_net *tn = net_generic(net, tipc_net_id);

	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
			  nlflags, TIPC_NL_LINK_GET);
	if (!hdr)
		return -EMSGSIZE;

	attrs = nla_nest_start(msg->skb, TIPC_NLA_LINK);
	if (!attrs)
		goto msg_full;

	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, link->name))
		goto attr_msg_full;
	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_DEST,
			tipc_cluster_mask(tn->own_addr)))
		goto attr_msg_full;
	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->mtu))
		goto attr_msg_full;
	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, link->stats.recv_pkts))
		goto attr_msg_full;
	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, link->stats.sent_pkts))
		goto attr_msg_full;

	if (tipc_link_is_up(link))
		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
			goto attr_msg_full;
	if (link->active)
		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_ACTIVE))
			goto attr_msg_full;

	prop = nla_nest_start(msg->skb, TIPC_NLA_LINK_PROP);
	if (!prop)
		goto attr_msg_full;
	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
		goto prop_msg_full;
	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_TOL, link->tolerance))
		goto prop_msg_full;
	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN,
			link->window))
		goto prop_msg_full;
	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
		goto prop_msg_full;
	nla_nest_end(msg->skb, prop);

	err = __tipc_nl_add_stats(msg->skb, &link->stats);
	if (err)
		goto attr_msg_full;

	nla_nest_end(msg->skb, attrs);
	genlmsg_end(msg->skb, hdr);

	return 0;

prop_msg_full:
	nla_nest_cancel(msg->skb, prop);
attr_msg_full:
	nla_nest_cancel(msg->skb, attrs);
msg_full:
	genlmsg_cancel(msg->skb, hdr);

	return -EMSGSIZE;
}

static int __tipc_nl_add_bc_link_stat(struct sk_buff *skb,
				      struct tipc_stats *stats)
{
	int i;
	struct nlattr *nest;

	struct nla_map {
		__u32 key;
		__u32 val;
	};

	struct nla_map map[] = {
		{TIPC_NLA_STATS_RX_INFO, stats->recv_pkts},
		{TIPC_NLA_STATS_RX_FRAGMENTS, stats->recv_fragments},
		{TIPC_NLA_STATS_RX_FRAGMENTED, stats->recv_fragmented},
		{TIPC_NLA_STATS_RX_BUNDLES, stats->recv_bundles},
		{TIPC_NLA_STATS_RX_BUNDLED, stats->recv_bundled},
		{TIPC_NLA_STATS_TX_INFO, stats->sent_pkts},
		{TIPC_NLA_STATS_TX_FRAGMENTS, stats->sent_fragments},
		{TIPC_NLA_STATS_TX_FRAGMENTED, stats->sent_fragmented},
		{TIPC_NLA_STATS_TX_BUNDLES, stats->sent_bundles},
		{TIPC_NLA_STATS_TX_BUNDLED, stats->sent_bundled},
		{TIPC_NLA_STATS_RX_NACKS, stats->recv_nacks},
		{TIPC_NLA_STATS_RX_DEFERRED, stats->deferred_recv},
		{TIPC_NLA_STATS_TX_NACKS, stats->sent_nacks},
		{TIPC_NLA_STATS_TX_ACKS, stats->sent_acks},
		{TIPC_NLA_STATS_RETRANSMITTED, stats->retransmitted},
		{TIPC_NLA_STATS_DUPLICATES, stats->duplicates},
		{TIPC_NLA_STATS_LINK_CONGS, stats->link_congs},
		{TIPC_NLA_STATS_MAX_QUEUE, stats->max_queue_sz},
		{TIPC_NLA_STATS_AVG_QUEUE, stats->queue_sz_counts ?
			(stats->accu_queue_sz / stats->queue_sz_counts) : 0}
	};

	nest = nla_nest_start(skb, TIPC_NLA_LINK_STATS);
	if (!nest)
		return -EMSGSIZE;

	for (i = 0; i <  ARRAY_SIZE(map); i++)
		if (nla_put_u32(skb, map[i].key, map[i].val))
			goto msg_full;

	nla_nest_end(skb, nest);

	return 0;
msg_full:
	nla_nest_cancel(skb, nest);

	return -EMSGSIZE;
}

int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg)
{
	int err;
	void *hdr;
	struct nlattr *attrs;
	struct nlattr *prop;
	struct tipc_net *tn = net_generic(net, tipc_net_id);
	struct tipc_link *bcl = tn->bcl;

	if (!bcl)
		return 0;

	tipc_bcast_lock(net);

	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
			  NLM_F_MULTI, TIPC_NL_LINK_GET);
	if (!hdr) {
		tipc_bcast_unlock(net);
		return -EMSGSIZE;
	}

	attrs = nla_nest_start(msg->skb, TIPC_NLA_LINK);
	if (!attrs)
		goto msg_full;

	/* The broadcast link is always up */
	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
		goto attr_msg_full;

	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_BROADCAST))
		goto attr_msg_full;
	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, bcl->name))
		goto attr_msg_full;
	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, 0))
		goto attr_msg_full;
	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, 0))
		goto attr_msg_full;

	prop = nla_nest_start(msg->skb, TIPC_NLA_LINK_PROP);
	if (!prop)
		goto attr_msg_full;
	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bcl->window))
		goto prop_msg_full;
	nla_nest_end(msg->skb, prop);

	err = __tipc_nl_add_bc_link_stat(msg->skb, &bcl->stats);
	if (err)
		goto attr_msg_full;

	tipc_bcast_unlock(net);
	nla_nest_end(msg->skb, attrs);
	genlmsg_end(msg->skb, hdr);

	return 0;

prop_msg_full:
	nla_nest_cancel(msg->skb, prop);
attr_msg_full:
	nla_nest_cancel(msg->skb, attrs);
msg_full:
	tipc_bcast_unlock(net);
	genlmsg_cancel(msg->skb, hdr);

	return -EMSGSIZE;
}

void tipc_link_set_tolerance(struct tipc_link *l, u32 tol,
			     struct sk_buff_head *xmitq)
{
	l->tolerance = tol;
	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, tol, 0, xmitq);
}

void tipc_link_set_prio(struct tipc_link *l, u32 prio,
			struct sk_buff_head *xmitq)
{
	l->priority = prio;
	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, prio, xmitq);
}

void tipc_link_set_abort_limit(struct tipc_link *l, u32 limit)
{
	l->abort_limit = limit;
}