aboutsummaryrefslogtreecommitdiffstats
path: root/src/vcl/vcl_locked.c
blob: 93ece0027ff55c0045bccdffdf9087b6a9d7d15d (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
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
/*
 * Copyright (c) 2021 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * VCL Locked Sessions (VLS) is a wrapper that synchronizes access to VCL APIs
 * which are, by construction, not thread safe. To this end, VLS uses
 * configuration and heuristics to detect how applications use sessions in
 * an attempt to optimize the locking strategy. The modes of operation
 * currently supported are the following:
 *
 *                    1) per-process workers
 *
 *                  +----------+   +----------+
 *                  |          |   |          |
 *                  | process0 |   | process1 |
 *                  |          |   |          |
 *                  +-----+----+   +-----+----+
 *                        |              |
 *                        |              |
 *                  +-----+----+   +-----+----+
 *                  |          |   |          |
 *                  | vls_wrk0 |   | vls_wrk1 |
 *                  |          |   |          |
 *                  +-----+----+   +-----+----+
 *                        |              |
 *                        |              |
 *                  +-----+----+   +-----+----+
 *                  |          |   |          |
 *                  | vcl_wrk0 |   | vcl_wrk1 |
 *                  |          |   |          |
 *                  +----------+   +----------+
 *
 *     2) per-thread workers         3) single-worker multi-thread
 *
 *   +---------+   +---------+         +---------+   +---------+
 *   |         |   |         |         |         |   |         |
 *   | thread0 |   | thread1 |         | thread0 |   | thread1 |
 *   |         |   |         |         |         |   |         |
 *   +--------++   +-+-------+         +--------++   +-+-------+
 *            |      |                          |      |
 *            |      |                          |      |
 *          +-+------+-+                      +-+------+-+
 *          |          |                      |          |
 *          | vls_wrk0 |                      | vls_wrk0 |
 *          |          |                      |          |
 *          +-+------+-+                      +----+-----+
 *            |      |                             |
 *            |      |                             |
 *   +--------+-+  +-+--------+               +----+-----+
 *   |          |  |          |               |          |
 *   | vcl_wrk0 |  | vcl_wrk1 |               | vcl_wrk0 |
 *   |          |  |          |               |          |
 *   +----------+  +----------+               +----------+
 *
 * 1) per-process workers: intercept fork calls and assume all children
 *    processes are new workers that must be registered with vcl. VLS
 *    sessions are cloned and shared between workers. Only shared sessions
 *    are locked on use and thereby only one process can interact with
 *    them at a time (explicit sharing).
 *
 * 2) per-thread workers: each newly detected pthread is assumed to be a new
 *    worker and is registered with vcl. Enabled via configuration.
 *    When a thread tries to access a session it does not own, a clone and
 *    share rpc request is sent to the owning thread via vcl and vpp.
 *    Consequently, a vls session can map to multiple vcl sessions, one per
 *    vcl worker. VLS sessions are locked on use (implicit sharing).
 *
 * 3) single-worker multi-thread: vls does not make any assumptions about
 *    application threads and therefore implements an aggressive locking
 *    strategy that limits access to underlying vcl resources based on type
 *    of interaction and locks vls session on use (implicit sharing).
 */

#include <vcl/vcl_locked.h>
#include <vcl/vcl_private.h>

typedef struct vls_shared_data_
{
  clib_spinlock_t lock;	    /**< shared data lock */
  u32 owner_wrk_index;	    /**< vcl wrk that owns session */
  u32 *workers_subscribed;  /**< vec of wrks subscribed to session */
  clib_bitmap_t *listeners; /**< bitmap of wrks actively listening */
} vls_shared_data_t;

typedef struct vcl_locked_session_
{
  clib_spinlock_t lock;	   /**< vls lock when in use */
  u32 session_index;	   /**< vcl session index */
  u32 vcl_wrk_index;	   /**< vcl worker index */
  u32 vls_index;	   /**< index in vls pool */
  u32 shared_data_index;   /**< shared data index if any */
  u32 owner_vcl_wrk_index; /**< vcl wrk of the vls wrk at alloc */
  uword *vcl_wrk_index_to_session_index; /**< map vcl wrk to session */
} vcl_locked_session_t;

typedef struct vls_worker_
{
  clib_rwlock_t sh_to_vlsh_table_lock; /**< ht rwlock with mt workers */
  vcl_locked_session_t *vls_pool;      /**< pool of vls session */
  uword *sh_to_vlsh_table;	       /**< map from vcl sh to vls sh */
  u32 *pending_vcl_wrk_cleanup;	       /**< child vcl wrks to cleanup */
  u32 vcl_wrk_index;		       /**< if 1:1 map vls to vcl wrk */
} vls_worker_t;

typedef struct vls_local_
{
  int vls_wrk_index;		      /**< vls wrk index, 1 per process */
  volatile int vls_mt_n_threads;      /**< number of threads detected */
  clib_rwlock_t vls_pool_lock;	      /**< per process/wrk vls pool locks */
  pthread_mutex_t vls_mt_mq_mlock;    /**< vcl mq lock */
  pthread_mutex_t vls_mt_spool_mlock; /**< vcl select or pool lock */
  volatile u8 select_mp_check;	      /**< flag set if select checks done */
} vls_process_local_t;

static vls_process_local_t vls_local;
static vls_process_local_t *vlsl = &vls_local;

typedef struct vls_main_
{
  vls_worker_t *workers;	       /**< pool of vls workers */
  vls_shared_data_t *shared_data_pool; /**< inter proc pool of shared data */
  clib_rwlock_t shared_data_lock;      /**< shared data pool lock */
  clib_spinlock_t worker_rpc_lock;     /**< lock for inter-worker rpcs */
} vls_main_t;

vls_main_t *vlsm;

typedef enum
{
  VLS_RPC_STATE_INIT,
  VLS_RPC_STATE_SUCCESS,
  VLS_RPC_STATE_SESSION_NOT_EXIST,
} vls_rpc_state_e;

typedef enum vls_rpc_msg_type_
{
  VLS_RPC_CLONE_AND_SHARE,
  VLS_RPC_SESS_CLEANUP,
} vls_rpc_msg_type_e;

typedef struct vls_rpc_msg_
{
  u8 type;
  u8 data[0];
} vls_rpc_msg_t;

typedef struct vls_clone_and_share_msg_
{
  u32 vls_index;		/**< vls to be shared */
  u32 session_index;		/**< vcl session to be shared */
  u32 origin_vls_wrk;		/**< vls worker that initiated the rpc */
  u32 origin_vls_index;		/**< vls session of the originator */
  u32 origin_vcl_wrk;		/**< vcl worker that initiated the rpc */
  u32 origin_session_index;	/**< vcl session of the originator */
} vls_clone_and_share_msg_t;

typedef struct vls_sess_cleanup_msg_
{
  u32 session_index;		/**< vcl session to be cleaned */
  u32 origin_vcl_wrk;		/**< worker that initiated the rpc */
} vls_sess_cleanup_msg_t;

void vls_send_session_cleanup_rpc (vcl_worker_t * wrk,
				   u32 dst_wrk_index, u32 dst_session_index);
void vls_send_clone_and_share_rpc (vcl_worker_t *wrk, u32 origin_vls_index,
				   u32 session_index, u32 vls_wrk_index,
				   u32 dst_wrk_index, u32 dst_vls_index,
				   u32 dst_session_index);
static void vls_cleanup_forked_child (vcl_worker_t *wrk,
				      vcl_worker_t *child_wrk);
static void vls_handle_pending_wrk_cleanup (void);

static inline u32
vls_get_worker_index (void)
{
  return vlsl->vls_wrk_index;
}

static u32
vls_shared_data_alloc (void)
{
  vls_shared_data_t *vls_shd;
  u32 shd_index;

  clib_rwlock_writer_lock (&vlsm->shared_data_lock);
  pool_get_zero (vlsm->shared_data_pool, vls_shd);
  clib_spinlock_init (&vls_shd->lock);
  shd_index = vls_shd - vlsm->shared_data_pool;
  clib_rwlock_writer_unlock (&vlsm->shared_data_lock);

  return shd_index;
}

static u32
vls_shared_data_index (vls_shared_data_t * vls_shd)
{
  return vls_shd - vlsm->shared_data_pool;
}

vls_shared_data_t *
vls_shared_data_get (u32 shd_index)
{
  if (pool_is_free_index (vlsm->shared_data_pool, shd_index))
    return 0;
  return pool_elt_at_index (vlsm->shared_data_pool, shd_index);
}

static void
vls_shared_data_free (u32 shd_index)
{
  vls_shared_data_t *vls_shd;

  clib_rwlock_writer_lock (&vlsm->shared_data_lock);
  vls_shd = vls_shared_data_get (shd_index);
  clib_spinlock_free (&vls_shd->lock);
  clib_bitmap_free (vls_shd->listeners);
  vec_free (vls_shd->workers_subscribed);
  pool_put (vlsm->shared_data_pool, vls_shd);
  clib_rwlock_writer_unlock (&vlsm->shared_data_lock);
}

static inline void
vls_shared_data_pool_rlock (void)
{
  clib_rwlock_reader_lock (&vlsm->shared_data_lock);
}

static inline void
vls_shared_data_pool_runlock (void)
{
  clib_rwlock_reader_unlock (&vlsm->shared_data_lock);
}

static inline void
vls_mt_pool_rlock (void)
{
  if (vlsl->vls_mt_n_threads > 1)
    clib_rwlock_reader_lock (&vlsl->vls_pool_lock);
}

static inline void
vls_mt_pool_runlock (void)
{
  if (vlsl->vls_mt_n_threads > 1)
    clib_rwlock_reader_unlock (&vlsl->vls_pool_lock);
}

static inline void
vls_mt_pool_wlock (void)
{
  if (vlsl->vls_mt_n_threads > 1)
    clib_rwlock_writer_lock (&vlsl->vls_pool_lock);
}

static inline void
vls_mt_pool_wunlock (void)
{
  if (vlsl->vls_mt_n_threads > 1)
    clib_rwlock_writer_unlock (&vlsl->vls_pool_lock);
}

typedef enum
{
  VLS_MT_OP_READ,
  VLS_MT_OP_WRITE,
  VLS_MT_OP_SPOOL,
  VLS_MT_OP_XPOLL,
} vls_mt_ops_t;

typedef enum
{
  VLS_MT_LOCK_MQ = 1 << 0,
  VLS_MT_LOCK_SPOOL = 1 << 1
} vls_mt_lock_type_t;

static void
vls_mt_add (void)
{
  vlsl->vls_mt_n_threads += 1;

  /* If multi-thread workers are supported, for each new thread register a new
   * vcl worker with vpp. Otherwise, all threads use the same vcl worker, so
   * update the vcl worker's thread local worker index variable */
  if (vls_mt_wrk_supported ())
    {
      if (vppcom_worker_register () != VPPCOM_OK)
	VERR ("failed to register worker");
    }
  else
    vcl_set_worker_index (vlsl->vls_wrk_index);
}

static inline void
vls_mt_mq_lock (void)
{
  pthread_mutex_lock (&vlsl->vls_mt_mq_mlock);
}

static inline void
vls_mt_mq_unlock (void)
{
  pthread_mutex_unlock (&vlsl->vls_mt_mq_mlock);
}

static inline void
vls_mt_spool_lock (void)
{
  pthread_mutex_lock (&vlsl->vls_mt_spool_mlock);
}

static inline void
vls_mt_create_unlock (void)
{
  pthread_mutex_unlock (&vlsl->vls_mt_spool_mlock);
}

static void
vls_mt_locks_init (void)
{
  pthread_mutex_init (&vlsl->vls_mt_mq_mlock, NULL);
  pthread_mutex_init (&vlsl->vls_mt_spool_mlock, NULL);
}

u8
vls_is_shared (vcl_locked_session_t * vls)
{
  return (vls->shared_data_index != ~0);
}

static inline void
vls_lock (vcl_locked_session_t * vls)
{
  if ((vlsl->vls_mt_n_threads > 1) || vls_is_shared (vls))
    clib_spinlock_lock (&vls->lock);
}

static inline void
vls_unlock (vcl_locked_session_t * vls)
{
  if ((vlsl->vls_mt_n_threads > 1) || vls_is_shared (vls))
    clib_spinlock_unlock (&vls->lock);
}

static inline vcl_session_handle_t
vls_to_sh (vcl_locked_session_t * vls)
{
  return vcl_session_handle_from_index (vls->session_index);
}

static inline vcl_session_handle_t
vls_to_sh_tu (vcl_locked_session_t * vls)
{
  vcl_session_handle_t sh;
  sh = vls_to_sh (vls);
  vls_mt_pool_runlock ();
  return sh;
}

static vls_worker_t *
vls_worker_get_current (void)
{
  return pool_elt_at_index (vlsm->workers, vls_get_worker_index ());
}

static inline u8
vls_n_workers (void)
{
  return pool_elts (vlsm->workers);
}

static void
vls_worker_alloc (void)
{
  vls_worker_t *wrk;

  pool_get_zero (vlsm->workers, wrk);
  if (vls_mt_wrk_supported ())
    clib_rwlock_init (&wrk->sh_to_vlsh_table_lock);
  wrk->vcl_wrk_index = vcl_get_worker_index ();
  vec_validate (wrk->pending_vcl_wrk_cleanup, 16);
  vec_reset_length (wrk->pending_vcl_wrk_cleanup);
}

static void
vls_worker_free (vls_worker_t * wrk)
{
  hash_free (wrk->sh_to_vlsh_table);
  if (vls_mt_wrk_supported ())
    clib_rwlock_free (&wrk->sh_to_vlsh_table_lock);
  pool_free (wrk->vls_pool);
  pool_put (vlsm->workers, wrk);
}

static vls_worker_t *
vls_worker_get (u32 wrk_index)
{
  if (pool_is_free_index (vlsm->workers, wrk_index))
    return 0;
  return pool_elt_at_index (vlsm->workers, wrk_index);
}

static void
vls_sh_to_vlsh_table_add (vls_worker_t *wrk, vcl_session_handle_t sh, u32 vlsh)
{
  if (vls_mt_wrk_supported ())
    clib_rwlock_writer_lock (&wrk->sh_to_vlsh_table_lock);
  hash_set (wrk->sh_to_vlsh_table, sh, vlsh);
  if (vls_mt_wrk_supported ())
    clib_rwlock_writer_unlock (&wrk->sh_to_vlsh_table_lock);
}

static void
vls_sh_to_vlsh_table_del (vls_worker_t *wrk, vcl_session_handle_t sh)
{
  if (vls_mt_wrk_supported ())
    clib_rwlock_writer_lock (&wrk->sh_to_vlsh_table_lock);
  hash_unset (wrk->sh_to_vlsh_table, sh);
  if (vls_mt_wrk_supported ())
    clib_rwlock_writer_unlock (&wrk->sh_to_vlsh_table_lock);
}

static uword *
vls_sh_to_vlsh_table_get (vls_worker_t *wrk, vcl_session_handle_t sh)
{
  if (vls_mt_wrk_supported ())
    clib_rwlock_reader_lock (&wrk->sh_to_vlsh_table_lock);
  uword *vlshp = hash_get (wrk->sh_to_vlsh_table, sh);
  if (vls_mt_wrk_supported ())
    clib_rwlock_reader_unlock (&wrk->sh_to_vlsh_table_lock);
  return vlshp;
}

static vls_handle_t
vls_alloc (vcl_session_handle_t sh)
{
  vls_worker_t *wrk = vls_worker_get_current ();
  vcl_locked_session_t *vls;

  vls_mt_pool_wlock ();

  pool_get_zero (wrk->vls_pool, vls);
  vls->session_index = vppcom_session_index (sh);
  vls->vcl_wrk_index = vppcom_session_worker (sh);
  vls->vls_index = vls - wrk->vls_pool;
  vls->shared_data_index = ~0;
  vls_sh_to_vlsh_table_add (wrk, sh, vls->vls_index);
  if (vls_mt_wrk_supported ())
    {
      hash_set (vls->vcl_wrk_index_to_session_index, vls->vcl_wrk_index,
		vls->session_index);
      vls->owner_vcl_wrk_index = vls->vcl_wrk_index;
    }
  clib_spinlock_init (&vls->lock);

  vls_mt_pool_wunlock ();
  return vls->vls_index;
}

static vcl_locked_session_t *
vls_get (vls_handle_t vlsh)
{
  vls_worker_t *wrk = vls_worker_get_current ();
  if (pool_is_free_index (wrk->vls_pool, vlsh))
    return 0;
  return pool_elt_at_index (wrk->vls_pool, vlsh);
}

static void
vls_free (vcl_locked_session_t * vls)
{
  vls_worker_t *wrk = vls_worker_get_current ();

  ASSERT (vls != 0);
  vls_sh_to_vlsh_table_del (
    wrk, vcl_session_handle_from_index (vls->session_index));
  clib_spinlock_free (&vls->lock);
  pool_put (wrk->vls_pool, vls);
}

static vcl_locked_session_t *
vls_get_and_lock (vls_handle_t vlsh)
{
  vls_worker_t *wrk = vls_worker_get_current ();
  vcl_locked_session_t *vls;
  if (pool_is_free_index (wrk->vls_pool, vlsh))
    return 0;
  vls = pool_elt_at_index (wrk->vls_pool, vlsh);
  vls_lock (vls);
  return vls;
}

static vcl_locked_session_t *
vls_get_w_dlock (vls_handle_t vlsh)
{
  vcl_locked_session_t *vls;
  vls_mt_pool_rlock ();
  vls = vls_get_and_lock (vlsh);
  if (!vls)
    vls_mt_pool_runlock ();
  return vls;
}

static inline void
vls_get_and_unlock (vls_handle_t vlsh)
{
  vcl_locked_session_t *vls;
  vls_mt_pool_rlock ();
  vls = vls_get (vlsh);
  vls_unlock (vls);
  vls_mt_pool_runlock ();
}

static inline void
vls_dunlock (vcl_locked_session_t * vls)
{
  vls_unlock (vls);
  vls_mt_pool_runlock ();
}

static vcl_locked_session_t *
vls_session_get (vls_worker_t * wrk, u32 vls_index)
{
  if (pool_is_free_index (wrk->vls_pool, vls_index))
    return 0;
  return pool_elt_at_index (wrk->vls_pool, vls_index);
}

vcl_session_handle_t
vlsh_to_sh (vls_handle_t vlsh)
{
  vcl_locked_session_t *vls;
  int rv;

  vls = vls_get_w_dlock (vlsh);
  if (!vls)
    return INVALID_SESSION_ID;
  rv = vls_to_sh (vls);
  vls_dunlock (vls);
  return rv;
}

vcl_session_handle_t
vlsh_to_session_index (vls_handle_t vlsh)
{
  vcl_session_handle_t sh;
  sh = vlsh_to_sh (vlsh);
  return vppcom_session_index (sh);
}

vls_handle_t
vls_si_wi_to_vlsh (u32 session_index, u32 vcl_wrk_index)
{
  vls_worker_t *wrk = vls_worker_get_current ();
  uword *vlshp = vls_sh_to_vlsh_table_get (
    wrk,
    vcl_session_handle_from_wrk_session_index (session_index, vcl_wrk_index));

  return vlshp ? *vlshp : VLS_INVALID_HANDLE;
}

vls_handle_t
vls_session_index_to_vlsh (uint32_t session_index)
{
  vls_handle_t vlsh;

  vls_mt_pool_rlock ();
  vlsh = vls_si_wi_to_vlsh (session_index, vcl_get_worker_index ());
  vls_mt_pool_runlock ();

  return vlsh;
}

u8
vls_is_shared_by_wrk (vcl_locked_session_t * vls, u32 wrk_index)
{
  vls_shared_data_t *vls_shd;
  int i;

  if (vls->shared_data_index == ~0)
    return 0;

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);
  clib_spinlock_lock (&vls_shd->lock);

  for (i = 0; i < vec_len (vls_shd->workers_subscribed); i++)
    if (vls_shd->workers_subscribed[i] == wrk_index)
      {
	clib_spinlock_unlock (&vls_shd->lock);
	vls_shared_data_pool_runlock ();
	return 1;
      }
  clib_spinlock_unlock (&vls_shd->lock);

  vls_shared_data_pool_runlock ();
  return 0;
}

static void
vls_listener_wrk_set (vcl_locked_session_t * vls, u32 wrk_index, u8 is_active)
{
  vls_shared_data_t *vls_shd;

  if (vls->shared_data_index == ~0)
    {
      clib_warning ("not a shared session");
      return;
    }

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);

  clib_spinlock_lock (&vls_shd->lock);
  vls_shd->listeners =
    clib_bitmap_set (vls_shd->listeners, wrk_index, is_active);
  clib_spinlock_unlock (&vls_shd->lock);

  vls_shared_data_pool_runlock ();
}

static u32
vls_shared_get_owner (vcl_locked_session_t * vls)
{
  vls_shared_data_t *vls_shd;
  u32 owner_wrk;

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);
  owner_wrk = vls_shd->owner_wrk_index;

  vls_shared_data_pool_runlock ();

  return owner_wrk;
}

static u8
vls_listener_wrk_is_active (vcl_locked_session_t * vls, u32 wrk_index)
{
  vls_shared_data_t *vls_shd;
  u8 is_set;

  if (vls->shared_data_index == ~0)
    {
      clib_warning ("not a shared session");
      return 0;
    }

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);

  clib_spinlock_lock (&vls_shd->lock);
  is_set = clib_bitmap_get (vls_shd->listeners, wrk_index);
  clib_spinlock_unlock (&vls_shd->lock);

  vls_shared_data_pool_runlock ();

  return (is_set == 1);
}

static void
vls_listener_wrk_start_listen (vcl_locked_session_t * vls, u32 wrk_index)
{
  vcl_worker_t *wrk;
  vcl_session_t *ls;

  wrk = vcl_worker_get (wrk_index);
  ls = vcl_session_get (wrk, vls->session_index);

  /* Listen request already sent */
  if (ls->flags & VCL_SESSION_F_PENDING_LISTEN)
    return;

  vcl_send_session_listen (wrk, ls);

  vls_listener_wrk_set (vls, wrk_index, 1 /* is_active */);
}

static void
vls_listener_wrk_stop_listen (vcl_locked_session_t * vls, u32 wrk_index)
{
  vcl_worker_t *wrk;
  vcl_session_t *s;

  wrk = vcl_worker_get (wrk_index);
  s = vcl_session_get (wrk, vls->session_index);
  if (s->session_state != VCL_STATE_LISTEN)
    return;
  vcl_send_session_unlisten (wrk, s);
  s->session_state = VCL_STATE_LISTEN_NO_MQ;
  vls_listener_wrk_set (vls, wrk_index, 0 /* is_active */ );
}

static int
vls_shared_data_subscriber_position (vls_shared_data_t * vls_shd,
				     u32 wrk_index)
{
  int i;

  for (i = 0; i < vec_len (vls_shd->workers_subscribed); i++)
    {
      if (vls_shd->workers_subscribed[i] == wrk_index)
	return i;
    }
  return -1;
}

int
vls_unshare_session (vcl_locked_session_t * vls, vcl_worker_t * wrk)
{
  vls_shared_data_t *vls_shd;
  int do_disconnect, pos;
  u32 n_subscribers;
  vcl_session_t *s;

  if (vls->shared_data_index == ~0)
    return 0;

  s = vcl_session_get (wrk, vls->session_index);
  if (s->session_state == VCL_STATE_LISTEN)
    vls_listener_wrk_set (vls, wrk->wrk_index, 0 /* is_active */ );

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);
  clib_spinlock_lock (&vls_shd->lock);

  pos = vls_shared_data_subscriber_position (vls_shd, wrk->wrk_index);
  if (pos < 0)
    {
      clib_warning ("worker %u not subscribed for vls %u", wrk->wrk_index,
		    vls->vcl_wrk_index);
      goto done;
    }

  /*
   * Unsubscribe from share data and fifos
   */
  if (s->rx_fifo)
    {
      svm_fifo_del_subscriber (s->rx_fifo, wrk->vpp_wrk_index);
      svm_fifo_del_subscriber (s->tx_fifo, wrk->vpp_wrk_index);
    }
  vec_del1 (vls_shd->workers_subscribed, pos);

  /*
   * Cleanup vcl state
   */
  n_subscribers = vec_len (vls_shd->workers_subscribed);
  do_disconnect = s->session_state == VCL_STATE_LISTEN || !n_subscribers;
  vcl_session_cleanup (wrk, s, vcl_session_handle (s), do_disconnect);

  /*
   * No subscriber left, cleanup shared data
   */
  if (!n_subscribers)
    {
      u32 shd_index = vls_shared_data_index (vls_shd);

      clib_spinlock_unlock (&vls_shd->lock);
      vls_shared_data_pool_runlock ();

      vls_shared_data_free (shd_index);

      /* All locks have been dropped */
      return 0;
    }

  /* Return, if this is not the owning worker */
  if (vls_shd->owner_wrk_index != wrk->wrk_index)
    goto done;

  ASSERT (vec_len (vls_shd->workers_subscribed));

  /*
   *  Check if we can change owner or close
   */
  vls_shd->owner_wrk_index = vls_shd->workers_subscribed[0];
  if (s->vpp_evt_q)
    vcl_send_session_worker_update (wrk, s, vls_shd->owner_wrk_index);

  /* XXX is this still needed? */
  if (vec_len (vls_shd->workers_subscribed) > 1)
    clib_warning ("more workers need to be updated");

done:

  clib_spinlock_unlock (&vls_shd->lock);
  vls_shared_data_pool_runlock ();

  return 0;
}

void
vls_init_share_session (vls_worker_t * vls_wrk, vcl_locked_session_t * vls)
{
  vls_shared_data_t *vls_shd;

  u32 vls_shd_index = vls_shared_data_alloc ();

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls_shd_index);
  vls_shd->owner_wrk_index = vls_wrk->vcl_wrk_index;
  vls->shared_data_index = vls_shd_index;
  vec_add1 (vls_shd->workers_subscribed, vls_wrk->vcl_wrk_index);

  vls_shared_data_pool_runlock ();
}

void
vls_share_session (vls_worker_t * vls_wrk, vcl_locked_session_t * vls)
{
  vcl_worker_t *vcl_wrk = vcl_worker_get (vls_wrk->vcl_wrk_index);
  vls_shared_data_t *vls_shd;
  vcl_session_t *s;

  s = vcl_session_get (vcl_wrk, vls->session_index);
  if (!s)
    {
      clib_warning ("wrk %u session %u vls %u NOT AVAILABLE",
		    vcl_wrk->wrk_index, vls->session_index, vls->vls_index);
      return;
    }

  ASSERT (vls->shared_data_index != ~0);

  /* Reinit session lock */
  clib_spinlock_init (&vls->lock);

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);

  clib_spinlock_lock (&vls_shd->lock);
  vec_add1 (vls_shd->workers_subscribed, vls_wrk->vcl_wrk_index);
  clib_spinlock_unlock (&vls_shd->lock);

  vls_shared_data_pool_runlock ();

  if (s->session_state == VCL_STATE_LISTEN)
    {
      s->session_state = VCL_STATE_LISTEN_NO_MQ;
      s->rx_fifo = s->tx_fifo = 0;
    }
  else if (s->rx_fifo)
    {
      vcl_session_share_fifos (s, s->rx_fifo, s->tx_fifo);
    }
}

static void
vls_share_sessions (vls_worker_t * vls_parent_wrk, vls_worker_t * vls_wrk)
{
  vcl_locked_session_t *vls, *parent_vls;

  pool_foreach (vls, vls_wrk->vls_pool)  {
    /* Initialize sharing on parent session */
    if (vls->shared_data_index == ~0)
      {
	parent_vls = vls_session_get (vls_parent_wrk, vls->vls_index);
	vls_init_share_session (vls_parent_wrk, parent_vls);
	vls->shared_data_index = parent_vls->shared_data_index;
      }
    vls_share_session (vls_wrk, vls);
  }
}

static void
vls_validate_veps (vcl_worker_t *wrk)
{
  vcl_session_t *s;
  u32 session_index, wrk_index;

  pool_foreach (s, wrk->sessions)
    {
      if (s->vep.vep_sh != ~0)
	{
	  vcl_session_handle_parse (s->vep.vep_sh, &wrk_index, &session_index);
	  s->vep.vep_sh = vcl_session_handle_from_index (session_index);
	}
      if (s->vep.next_sh != ~0)
	{
	  vcl_session_handle_parse (s->vep.next_sh, &wrk_index,
				    &session_index);
	  s->vep.next_sh = vcl_session_handle_from_index (session_index);
	}
      if (s->vep.prev_sh != ~0)
	{
	  vcl_session_handle_parse (s->vep.prev_sh, &wrk_index,
				    &session_index);
	  s->vep.prev_sh = vcl_session_handle_from_index (session_index);
	}
    }
}

void
vls_worker_copy_on_fork (vcl_worker_t * parent_wrk)
{
  vls_worker_t *vls_wrk = vls_worker_get_current (), *vls_parent_wrk;
  vcl_worker_t *vcl_wrk = vcl_worker_get_current ();
  u32 vls_index, session_index, wrk_index;
  vcl_session_handle_t sh;
  vcl_locked_session_t *vls;

  /*
   * init vcl worker
   */
  vcl_wrk->sessions = pool_dup (parent_wrk->sessions);
  vcl_wrk->session_index_by_vpp_handles =
    hash_dup (parent_wrk->session_index_by_vpp_handles);

  /*
   * init vls worker
   */
  vls_parent_wrk = vls_worker_get (parent_wrk->wrk_index);

  /* clang-format off */
  hash_foreach (sh, vls_index, vls_parent_wrk->sh_to_vlsh_table, ({
    vcl_session_handle_parse (sh, &wrk_index, &session_index);
    hash_set (vls_wrk->sh_to_vlsh_table,
              vcl_session_handle_from_index (session_index), vls_index);
  }));
  /* clang-format on */
  vls_wrk->vls_pool = pool_dup (vls_parent_wrk->vls_pool);

  /*
   * Detach vls from parent vcl worker and attach them to child.
   */
  pool_foreach (vls, vls_wrk->vls_pool)
    {
      vls->vcl_wrk_index = vcl_wrk->wrk_index;
    }

  /* Validate vep's handle */
  vls_validate_veps (vcl_wrk);

  vls_share_sessions (vls_parent_wrk, vls_wrk);
}

static void
vls_mt_acq_locks (vcl_locked_session_t * vls, vls_mt_ops_t op, int *locks_acq)
{
  vcl_worker_t *wrk = vcl_worker_get_current ();
  vcl_session_t *s = 0;
  int is_nonblk = 0;

  if (vls)
    {
      s = vcl_session_get (wrk, vls->session_index);
      if (PREDICT_FALSE (!s))
	return;
      is_nonblk = vcl_session_has_attr (s, VCL_SESS_ATTR_NONBLOCK);
    }

  switch (op)
    {
    case VLS_MT_OP_READ:
      if (!is_nonblk)
	is_nonblk = vcl_session_read_ready (s) != 0;
      if (!is_nonblk)
	{
	  vls_mt_mq_lock ();
	  *locks_acq |= VLS_MT_LOCK_MQ;
	}
      break;
    case VLS_MT_OP_WRITE:
      ASSERT (s);
      if (!is_nonblk)
	is_nonblk = vcl_session_write_ready (s) != 0;
      if (!is_nonblk)
	{
	  vls_mt_mq_lock ();
	  *locks_acq |= VLS_MT_LOCK_MQ;
	}
      break;
    case VLS_MT_OP_XPOLL:
      vls_mt_mq_lock ();
      *locks_acq |= VLS_MT_LOCK_MQ;
      break;
    case VLS_MT_OP_SPOOL:
      vls_mt_spool_lock ();
      *locks_acq |= VLS_MT_LOCK_SPOOL;
      break;
    default:
      break;
    }
}

static void
vls_mt_rel_locks (int locks_acq)
{
  if (locks_acq & VLS_MT_LOCK_MQ)
    vls_mt_mq_unlock ();
  if (locks_acq & VLS_MT_LOCK_SPOOL)
    vls_mt_create_unlock ();
}

static inline u8
vls_mt_session_should_migrate (vcl_locked_session_t * vls)
{
  return (vls_mt_wrk_supported () &&
	  vls->vcl_wrk_index != vcl_get_worker_index ());
}

static vcl_locked_session_t *
vls_mt_session_migrate (vcl_locked_session_t *vls)
{
  u32 wrk_index = vcl_get_worker_index ();
  vcl_worker_t *wrk;
  vls_worker_t *vls_wrk = vls_worker_get_current ();
  u32 src_sid, sid, vls_index, own_vcl_wrk_index;
  vcl_session_t *session;
  uword *p;

  ASSERT (vls_mt_wrk_supported () && vls->vcl_wrk_index != wrk_index);

  /*
   * VCL session on current vcl worker already allocated. Update current
   * owner worker and index and return
   */
  if ((p = hash_get (vls->vcl_wrk_index_to_session_index, wrk_index)))
    {
      vls->vcl_wrk_index = wrk_index;
      vls->session_index = (u32) p[0];
      return vls;
    }

  /*
   * Ask vcl worker that owns the original vcl session to clone it into
   * current vcl worker session pool
   */

  if (!(p = hash_get (vls->vcl_wrk_index_to_session_index,
		      vls->owner_vcl_wrk_index)))
    {
      VERR ("session in owner worker(%u) is free", vls->owner_vcl_wrk_index);
      ASSERT (0);
      vls_unlock (vls);
      vls_mt_pool_runlock ();
      return 0;
    }

  src_sid = (u32) p[0];
  wrk = vcl_worker_get_current ();
  session = vcl_session_alloc (wrk);
  sid = session->session_index;
  VDBG (1, "migrate session of worker (session): %u (%u) -> %u (%u)",
	vls->owner_vcl_wrk_index, src_sid, wrk_index, sid);

  /* Drop lock to prevent dead lock when dst wrk trying to get lock. */
  vls_index = vls->vls_index;
  own_vcl_wrk_index = vls->owner_vcl_wrk_index;
  vls_unlock (vls);
  vls_mt_pool_runlock ();
  vls_send_clone_and_share_rpc (wrk, vls_index, sid, vls_get_worker_index (),
				own_vcl_wrk_index, vls_index, src_sid);

  if (PREDICT_FALSE (wrk->rpc_done == VLS_RPC_STATE_SESSION_NOT_EXIST))
    {
      VWRN ("session %u not exist", src_sid);
      goto err;
    }
  else if (PREDICT_FALSE (wrk->rpc_done == VLS_RPC_STATE_INIT))
    {
      VWRN ("failed to wait rpc response");
      goto err;
    }
  else if (PREDICT_FALSE ((session->flags & VCL_SESSION_F_IS_VEP) &&
			  session->vep.next_sh != ~0))
    {
      VERR ("can't migrate nonempty epoll session");
      ASSERT (0);
      goto err;
    }
  else if (PREDICT_FALSE (!(session->flags & VCL_SESSION_F_IS_VEP) &&
			  session->session_state != VCL_STATE_CLOSED))
    {
      VERR ("migrate NOT supported, session_status (%u)",
	    session->session_state);
      ASSERT (0);
      goto err;
    }

  vls = vls_get_w_dlock (vls_index);
  if (PREDICT_FALSE (!vls))
    {
      VWRN ("failed to get vls %u", vls_index);
      goto err;
    }

  session->session_index = sid;
  vls->vcl_wrk_index = wrk_index;
  vls->session_index = sid;
  hash_set (vls->vcl_wrk_index_to_session_index, wrk_index, sid);
  vls_sh_to_vlsh_table_add (vls_wrk, vcl_session_handle (session),
			    vls->vls_index);
  return vls;

err:
  vcl_session_free (wrk, session);
  return 0;
}

static inline void
vls_mt_detect (void)
{
  if (PREDICT_FALSE (vcl_get_worker_index () == ~0))
    vls_mt_add ();
}

#define vls_mt_guard(_vls, _op)                                               \
  int _locks_acq = 0;                                                         \
  if (vls_mt_wrk_supported ())                                                \
    {                                                                         \
      if (PREDICT_FALSE (_vls &&                                              \
			 ((vcl_locked_session_t *) _vls)->vcl_wrk_index !=    \
			   vcl_get_worker_index ()))                          \
	{                                                                     \
	  _vls = vls_mt_session_migrate (_vls);                               \
	  if (PREDICT_FALSE (!_vls))                                          \
	    return VPPCOM_EBADFD;                                             \
	}                                                                     \
    }                                                                         \
  else                                                                        \
    {                                                                         \
      if (PREDICT_FALSE (vlsl->vls_mt_n_threads > 1))                         \
	vls_mt_acq_locks (_vls, _op, &_locks_acq);                            \
    }

#define vls_mt_unguard()						\
  if (PREDICT_FALSE (_locks_acq))					\
    vls_mt_rel_locks (_locks_acq)

int
vls_write (vls_handle_t vlsh, void *buf, size_t nbytes)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;

  vls_mt_guard (vls, VLS_MT_OP_WRITE);
  rv = vppcom_session_write (vls_to_sh_tu (vls), buf, nbytes);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_write_msg (vls_handle_t vlsh, void *buf, size_t nbytes)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_WRITE);
  rv = vppcom_session_write_msg (vls_to_sh_tu (vls), buf, nbytes);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_sendto (vls_handle_t vlsh, void *buf, int buflen, int flags,
	    vppcom_endpt_t * ep)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_WRITE);
  rv = vppcom_session_sendto (vls_to_sh_tu (vls), buf, buflen, flags, ep);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

ssize_t
vls_read (vls_handle_t vlsh, void *buf, size_t nbytes)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_READ);
  rv = vppcom_session_read (vls_to_sh_tu (vls), buf, nbytes);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

ssize_t
vls_recvfrom (vls_handle_t vlsh, void *buffer, uint32_t buflen, int flags,
	      vppcom_endpt_t * ep)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_READ);
  rv = vppcom_session_recvfrom (vls_to_sh_tu (vls), buffer, buflen, flags,
				ep);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_attr (vls_handle_t vlsh, uint32_t op, void *buffer, uint32_t * buflen)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  if (vls_mt_session_should_migrate (vls))
    {
      vls = vls_mt_session_migrate (vls);
      if (PREDICT_FALSE (!vls))
	return VPPCOM_EBADFD;
    }
  rv = vppcom_session_attr (vls_to_sh_tu (vls), op, buffer, buflen);
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_bind (vls_handle_t vlsh, vppcom_endpt_t * ep)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  rv = vppcom_session_bind (vls_to_sh_tu (vls), ep);
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_listen (vls_handle_t vlsh, int q_len)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_XPOLL);
  rv = vppcom_session_listen (vls_to_sh_tu (vls), q_len);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_connect (vls_handle_t vlsh, vppcom_endpt_t * server_ep)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_XPOLL);
  rv = vppcom_session_connect (vls_to_sh_tu (vls), server_ep);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

static inline void
vls_mp_checks (vcl_locked_session_t * vls, int is_add)
{
  vcl_worker_t *wrk = vcl_worker_get_current ();
  vcl_session_t *s;
  u32 owner_wrk;

  if (vls_mt_wrk_supported () && vls_n_workers () <= 1)
    return;

  ASSERT (wrk->wrk_index == vls->vcl_wrk_index);
  s = vcl_session_get (wrk, vls->session_index);
  switch (s->session_state)
    {
    case VCL_STATE_LISTEN:
      if (is_add)
	{
	  vls_listener_wrk_set (vls, vls->vcl_wrk_index, 1 /* is_active */);
	  break;
	}
      /* Although removal from epoll means listener no longer accepts new
       * sessions, the accept queue built by vpp cannot be drained by stopping
       * the listener. Morover, some applications, e.g., nginx, might
       * constantly remove and add listeners to their epfds. Removing
       * listeners in such situations causes a lot of churn in vpp as segments
       * and segment managers need to be recreated. */
      /* vls_listener_wrk_stop_listen (vls, vls->vcl_wrk_index); */
      break;
    case VCL_STATE_LISTEN_NO_MQ:
      if (!is_add)
	break;

      /* Register worker as listener */
      vls_listener_wrk_start_listen (vls, vls->vcl_wrk_index);

      /* If owner worker did not attempt to accept/xpoll on the session,
       * force a listen stop for it, since it may not be interested in
       * accepting new sessions.
       * This is pretty much a hack done to give app workers the illusion
       * that it is fine to listen and not accept new sessions for a
       * given listener. Without it, we would accumulate unhandled
       * accepts on the passive worker message queue. */
      owner_wrk = vls_shared_get_owner (vls);
      if (!vls_listener_wrk_is_active (vls, owner_wrk))
	vls_listener_wrk_stop_listen (vls, owner_wrk);
      break;
    default:
      break;
    }
}

vls_handle_t
vls_accept (vls_handle_t listener_vlsh, vppcom_endpt_t * ep, int flags)
{
  vls_handle_t accepted_vlsh;
  vcl_locked_session_t *vls;
  int sh;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (listener_vlsh)))
    return VPPCOM_EBADFD;
  if (vcl_n_workers () > 1)
    vls_mp_checks (vls, 1 /* is_add */ );
  vls_mt_guard (vls, VLS_MT_OP_SPOOL);
  sh = vppcom_session_accept (vls_to_sh_tu (vls), ep, flags);
  vls_mt_unguard ();
  vls_get_and_unlock (listener_vlsh);
  if (sh < 0)
    return sh;
  accepted_vlsh = vls_alloc (sh);
  if (PREDICT_FALSE (accepted_vlsh == VLS_INVALID_HANDLE))
    vppcom_session_close (sh);
  return accepted_vlsh;
}

vls_handle_t
vls_create (uint8_t proto, uint8_t is_nonblocking)
{
  vcl_session_handle_t sh;
  vls_handle_t vlsh;
  vcl_locked_session_t *vls = NULL;

  vls_mt_detect ();
  vls_mt_guard (vls, VLS_MT_OP_SPOOL);
  sh = vppcom_session_create (proto, is_nonblocking);
  vls_mt_unguard ();
  if (sh == INVALID_SESSION_ID)
    return VLS_INVALID_HANDLE;

  vlsh = vls_alloc (sh);
  if (PREDICT_FALSE (vlsh == VLS_INVALID_HANDLE))
    vppcom_session_close (sh);

  return vlsh;
}

static void
vls_mt_session_cleanup (vcl_locked_session_t * vls)
{
  u32 session_index, wrk_index, current_vcl_wrk;
  vcl_worker_t *wrk = vcl_worker_get_current ();

  ASSERT (vls_mt_wrk_supported ());

  current_vcl_wrk = vcl_get_worker_index ();

  hash_foreach (wrk_index, session_index, vls->vcl_wrk_index_to_session_index,
    ({
      if (current_vcl_wrk != wrk_index)
	vls_send_session_cleanup_rpc (wrk, wrk_index, session_index);
    }));
  hash_free (vls->vcl_wrk_index_to_session_index);
}

int
vls_close (vls_handle_t vlsh)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_mt_detect ();
  vls_mt_pool_wlock ();

  vls = vls_get_and_lock (vlsh);
  if (!vls)
    {
      vls_mt_pool_wunlock ();
      return VPPCOM_EBADFD;
    }

  vls_mt_guard (vls, VLS_MT_OP_SPOOL);

  if (vls_is_shared (vls))
    rv = vls_unshare_session (vls, vcl_worker_get_current ());
  else
    rv = vppcom_session_close (vls_to_sh (vls));

  if (vls_mt_wrk_supported ())
    vls_mt_session_cleanup (vls);

  vls_free (vls);
  vls_mt_unguard ();

  vls_mt_pool_wunlock ();

  return rv;
}

int
vls_shutdown (vls_handle_t vlsh, int how)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;

  vls_mt_guard (vls, VLS_MT_OP_SPOOL);
  rv = vppcom_session_shutdown (vls_to_sh_tu (vls), how);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);

  return rv;
}

vls_handle_t
vls_epoll_create (void)
{
  vcl_session_handle_t sh;
  vls_handle_t vlsh;

  vls_mt_detect ();

  sh = vppcom_epoll_create ();
  if (sh == INVALID_SESSION_ID)
    return VLS_INVALID_HANDLE;

  vlsh = vls_alloc (sh);
  if (vlsh == VLS_INVALID_HANDLE)
    vppcom_session_close (sh);

  return vlsh;
}

static void
vls_epoll_ctl_mp_checks (vcl_locked_session_t * vls, int op)
{
  if (vcl_n_workers () <= 1 || op == EPOLL_CTL_MOD)
    return;

  vls_mp_checks (vls, op == EPOLL_CTL_ADD);
}

int
vls_epoll_ctl (vls_handle_t ep_vlsh, int op, vls_handle_t vlsh,
	       struct epoll_event *event)
{
  vcl_locked_session_t *ep_vls, *vls;
  vcl_session_handle_t ep_sh, sh;
  int rv;

  vls_mt_detect ();
  vls_mt_pool_rlock ();

  ep_vls = vls_get_and_lock (ep_vlsh);
  if (PREDICT_FALSE (!ep_vls))
    {
      vls_mt_pool_runlock ();
      return VPPCOM_EBADFD;
    }

  if (vls_mt_session_should_migrate (ep_vls))
    {
      ep_vls = vls_mt_session_migrate (ep_vls);
      if (PREDICT_FALSE (!ep_vls))
	{
	  vls_mt_pool_runlock ();
	  return VPPCOM_EBADFD;
	}
    }

  vls = vls_get_and_lock (vlsh);
  if (PREDICT_FALSE (!vls))
    {
      vls_unlock (ep_vls);
      vls_mt_pool_runlock ();
      return VPPCOM_EBADFD;
    }

  ep_sh = vls_to_sh (ep_vls);
  sh = vls_to_sh (vls);

  vls_epoll_ctl_mp_checks (vls, op);
  vls_mt_pool_runlock ();
  rv = vppcom_epoll_ctl (ep_sh, op, sh, event);

  vls_mt_pool_rlock ();
  ep_vls = vls_get (ep_vlsh);
  vls = vls_get (vlsh);
  vls_unlock (vls);
  vls_unlock (ep_vls);
  vls_mt_pool_runlock ();
  return rv;
}

int
vls_epoll_wait (vls_handle_t ep_vlsh, struct epoll_event *events,
		int maxevents, double wait_for_time)
{
  vcl_locked_session_t *vls, *vls_tmp = NULL;
  int rv;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (ep_vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls_tmp, VLS_MT_OP_XPOLL);
  rv = vppcom_epoll_wait (vls_to_sh_tu (vls), events, maxevents,
			  wait_for_time);
  vls_mt_unguard ();
  vls_get_and_unlock (ep_vlsh);
  vls_handle_pending_wrk_cleanup ();
  return rv;
}

static void
vls_select_mp_checks (vcl_si_set * read_map)
{
  vcl_locked_session_t *vls;
  vcl_worker_t *wrk;
  vcl_session_t *s;
  u32 si;

  if (vcl_n_workers () <= 1)
    {
      vlsl->select_mp_check = 1;
      return;
    }

  if (!read_map)
    return;

  vlsl->select_mp_check = 1;
  wrk = vcl_worker_get_current ();

  clib_bitmap_foreach (si, read_map)  {
    s = vcl_session_get (wrk, si);
    if (s->session_state == VCL_STATE_LISTEN)
      {
	vls = vls_get (vls_session_index_to_vlsh (si));
	vls_mp_checks (vls, 1 /* is_add */);
      }
  }
}

int
vls_select (int n_bits, vcl_si_set * read_map, vcl_si_set * write_map,
	    vcl_si_set * except_map, double wait_for_time)
{
  int rv;
  vcl_locked_session_t *vls = NULL;

  vls_mt_detect ();
  vls_mt_guard (vls, VLS_MT_OP_XPOLL);
  if (PREDICT_FALSE (!vlsl->select_mp_check))
    vls_select_mp_checks (read_map);
  rv = vppcom_select (n_bits, read_map, write_map, except_map, wait_for_time);
  vls_mt_unguard ();
  vls_handle_pending_wrk_cleanup ();
  return rv;
}

static void
vls_unshare_vcl_worker_sessions (vcl_worker_t * wrk)
{
  u32 current_wrk, is_current;
  vcl_locked_session_t *vls;
  vcl_session_t *s;

  if (pool_elts (vcm->workers) <= 1)
    return;

  current_wrk = vcl_get_worker_index ();
  is_current = current_wrk == wrk->wrk_index;

  pool_foreach (s, wrk->sessions)  {
    vls = vls_get (vls_si_wi_to_vlsh (s->session_index, wrk->wrk_index));
    if (vls && (is_current || vls_is_shared_by_wrk (vls, current_wrk)))
      vls_unshare_session (vls, wrk);
  }
}

static void
vls_cleanup_vcl_worker (vcl_worker_t * wrk)
{
  vls_worker_t *vls_wrk = vls_worker_get (wrk->wrk_index);

  /* Unshare sessions and also cleanup worker since child may have
   * called _exit () and therefore vcl may not catch the event */
  vls_unshare_vcl_worker_sessions (wrk);

  /* Since child may have exited and thereforce fd of vpp_app_socket_api
   * may have been closed, so DONOT notify VPP.
   */
  vcl_worker_cleanup (wrk, vcm->cfg.vpp_app_socket_api ? 0 : 1);

  vls_worker_free (vls_wrk);
}

static void
vls_cleanup_forked_child (vcl_worker_t * wrk, vcl_worker_t * child_wrk)
{
  vcl_worker_t *sub_child;
  int tries = 0;

  if (child_wrk->forked_child != ~0)
    {
      sub_child = vcl_worker_get_if_valid (child_wrk->forked_child);
      if (sub_child)
	{
	  /* Wait a bit, maybe the process is going away */
	  while (kill (sub_child->current_pid, 0) >= 0 && tries++ < 50)
	    usleep (1e3);
	  if (kill (sub_child->current_pid, 0) < 0)
	    vls_cleanup_forked_child (child_wrk, sub_child);
	}
    }
  vls_cleanup_vcl_worker (child_wrk);
  VDBG (0, "Cleaned up forked child wrk %u", child_wrk->wrk_index);
  wrk->forked_child = ~0;
}

static void
vls_handle_pending_wrk_cleanup (void)
{
  u32 *wip;
  vcl_worker_t *child_wrk, *wrk;
  vls_worker_t *vls_wrk = vls_worker_get_current ();

  if (PREDICT_TRUE (vec_len (vls_wrk->pending_vcl_wrk_cleanup) == 0))
    return;

  wrk = vcl_worker_get_current ();
  vec_foreach (wip, vls_wrk->pending_vcl_wrk_cleanup)
    {
      child_wrk = vcl_worker_get_if_valid (*wip);
      if (!child_wrk)
	continue;
      vls_cleanup_forked_child (wrk, child_wrk);
    }
  vec_reset_length (vls_wrk->pending_vcl_wrk_cleanup);
}

static struct sigaction old_sa;

static void
vls_intercept_sigchld_handler (int signum, siginfo_t * si, void *uc)
{
  vcl_worker_t *wrk, *child_wrk;
  vls_worker_t *vls_wrk;

  if (vcl_get_worker_index () == ~0)
    return;

  if (sigaction (SIGCHLD, &old_sa, 0))
    {
      VERR ("couldn't restore sigchld");
      exit (-1);
    }

  wrk = vcl_worker_get_current ();
  if (wrk->forked_child == ~0)
    return;

  child_wrk = vcl_worker_get_if_valid (wrk->forked_child);
  if (!child_wrk)
    goto done;

  if (si && si->si_pid != child_wrk->current_pid)
    {
      VDBG (0, "unexpected child pid %u", si->si_pid);
      goto done;
    }

  /* Parent process may enter sighandler with a lock, such as lock in localtime
   * or in mspace_free, and child wrk cleanup may try to get such locks and
   * cause deadlock.
   * So move child wrk cleanup from sighandler to vls_epoll_wait/vls_select.
   */
  vls_wrk = vls_worker_get_current ();
  vec_add1 (vls_wrk->pending_vcl_wrk_cleanup, child_wrk->wrk_index);

done:
  if (old_sa.sa_flags & SA_SIGINFO)
    {
      void (*fn) (int, siginfo_t *, void *) = old_sa.sa_sigaction;
      fn (signum, si, uc);
    }
  else
    {
      void (*fn) (int) = old_sa.sa_handler;
      if (fn)
	fn (signum);
    }
}

static void
vls_incercept_sigchld ()
{
  struct sigaction sa;
  if (old_sa.sa_sigaction)
    {
      VDBG (0, "have intercepted sigchld");
      return;
    }
  clib_memset (&sa, 0, sizeof (sa));
  sa.sa_sigaction = vls_intercept_sigchld_handler;
  sa.sa_flags = SA_SIGINFO;
  if (sigaction (SIGCHLD, &sa, &old_sa))
    {
      VERR ("couldn't intercept sigchld");
      exit (-1);
    }
}

static void
vls_app_pre_fork (void)
{
  vls_incercept_sigchld ();
  vcl_flush_mq_events ();
}

static void
vls_app_fork_child_handler (void)
{
  vcl_worker_t *parent_wrk;
  int parent_wrk_index;

  parent_wrk_index = vcl_get_worker_index ();
  VDBG (0, "initializing forked child %u with parent wrk %u", getpid (),
	parent_wrk_index);

  /*
   * Clear old state
   */
  vcl_set_worker_index (~0);

  /*
   * Allocate and register vcl worker with vpp
   */
  if (vppcom_worker_register ())
    {
      VERR ("couldn't register new worker!");
      return;
    }

  /*
   * Allocate/initialize vls worker and share sessions
   */
  vls_worker_alloc ();

  /* Reset number of threads and set wrk index */
  vlsl->vls_mt_n_threads = 0;
  vlsl->vls_wrk_index = vcl_get_worker_index ();
  vlsl->select_mp_check = 0;
  clib_rwlock_init (&vlsl->vls_pool_lock);
  vls_mt_locks_init ();

  parent_wrk = vcl_worker_get (parent_wrk_index);
  vls_worker_copy_on_fork (parent_wrk);
  parent_wrk->forked_child = vcl_get_worker_index ();

  VDBG (0, "forked child main worker initialized");
  vcm->forking = 0;
}

static void
vls_app_fork_parent_handler (void)
{
  vcm->forking = 1;
  while (vcm->forking)
    ;
}

void
vls_app_exit (void)
{
  vls_worker_t *wrk = vls_worker_get_current ();

  /* Handle pending wrk cleanup */
  vls_handle_pending_wrk_cleanup ();

  /* Unshare the sessions. VCL will clean up the worker */
  vls_unshare_vcl_worker_sessions (vcl_worker_get_current ());
  vls_worker_free (wrk);
}

static void
vls_clone_and_share_rpc_handler (void *args)
{
  vls_clone_and_share_msg_t *msg = (vls_clone_and_share_msg_t *) args;
  vls_worker_t *wrk = vls_worker_get_current (), *dst_wrk;
  vcl_locked_session_t *vls, *dst_vls;
  vcl_worker_t *vcl_wrk = vcl_worker_get_current (), *dst_vcl_wrk;
  vcl_session_t *s, *dst_s;

  VDBG (1, "process session clone of worker (session): %u (%u) -> %u (%u)",
	vcl_wrk->wrk_index, msg->session_index, msg->origin_vcl_wrk,
	msg->origin_session_index);

  /* VCL locked session can't been protected, so DONT touch it.
   * VCL session may been free, check it.
   */
  dst_vcl_wrk = vcl_worker_get (msg->origin_vcl_wrk);
  s = vcl_session_get (vcl_wrk, msg->session_index);
  if (PREDICT_FALSE (!s))
    {
      dst_vcl_wrk->rpc_done = VLS_RPC_STATE_SESSION_NOT_EXIST;
      return;
    }

  if (!vls_mt_wrk_supported ())
    {
      vls = vls_session_get (wrk, msg->vls_index);
      vls_init_share_session (wrk, vls);
      dst_wrk = vls_worker_get (msg->origin_vls_wrk);
      dst_vls = vls_session_get (dst_wrk, msg->origin_vls_index);
      dst_vls->shared_data_index = vls->shared_data_index;
    }
  dst_s = vcl_session_get (dst_vcl_wrk, msg->origin_session_index);
  clib_memcpy (dst_s, s, sizeof (*s));

  dst_vcl_wrk->rpc_done = VLS_RPC_STATE_SUCCESS;
}

static void
vls_session_cleanup_rpc_handler (void *args)
{
  vls_sess_cleanup_msg_t *msg = (vls_sess_cleanup_msg_t *) args;
  vcl_worker_t *wrk = vcl_worker_get_current ();
  vls_worker_t *vls_wrk = vls_worker_get_current ();
  vcl_session_handle_t sh = vcl_session_handle_from_index (msg->session_index);

  VDBG (1, "process session cleanup of worker (session): %u (%u) from %u ()",
	wrk->wrk_index, msg->session_index, msg->origin_vcl_wrk);

  vppcom_session_close (sh);
  vls_sh_to_vlsh_table_del (vls_wrk, sh);
}

static void
vls_rpc_handler (void *args)
{
  vls_rpc_msg_t *msg = (vls_rpc_msg_t *) args;
  switch (msg->type)
    {
    case VLS_RPC_CLONE_AND_SHARE:
      vls_clone_and_share_rpc_handler (msg->data);
      break;
    case VLS_RPC_SESS_CLEANUP:
      vls_session_cleanup_rpc_handler (msg->data);
      break;
    default:
      break;
    }
}

void
vls_send_clone_and_share_rpc (vcl_worker_t *wrk, u32 origin_vls_index,
			      u32 session_index, u32 vls_wrk_index,
			      u32 dst_wrk_index, u32 dst_vls_index,
			      u32 dst_session_index)
{
  u8 data[sizeof (u8) + sizeof (vls_clone_and_share_msg_t)];
  vls_clone_and_share_msg_t *msg;
  vls_rpc_msg_t *rpc;
  int ret;
  f64 timeout = clib_time_now (&wrk->clib_time) + VLS_WORKER_RPC_TIMEOUT;

  rpc = (vls_rpc_msg_t *) & data;
  rpc->type = VLS_RPC_CLONE_AND_SHARE;
  msg = (vls_clone_and_share_msg_t *) & rpc->data;
  msg->origin_vls_wrk = vls_wrk_index;
  msg->origin_vls_index = origin_vls_index;
  msg->origin_vcl_wrk = wrk->wrk_index;
  msg->origin_session_index = session_index;
  msg->vls_index = dst_vls_index;
  msg->session_index = dst_session_index;

  /* Try lock and handle rpcs if two threads send each other
   * clone requests at the same time.
   */
  wrk->rpc_done = VLS_RPC_STATE_INIT;
  while (!clib_spinlock_trylock (&vlsm->worker_rpc_lock))
    vcl_flush_mq_events ();
  ret = vcl_send_worker_rpc (dst_wrk_index, rpc, sizeof (data));

  VDBG (1, "send session clone to wrk (session): %u (%u) -> %u (%u), ret=%d",
	dst_wrk_index, msg->session_index, msg->origin_vcl_wrk,
	msg->origin_session_index, ret);
  while (!ret && wrk->rpc_done == VLS_RPC_STATE_INIT &&
	 clib_time_now (&wrk->clib_time) < timeout)
    ;
  clib_spinlock_unlock (&vlsm->worker_rpc_lock);
}

void
vls_send_session_cleanup_rpc (vcl_worker_t * wrk,
			      u32 dst_wrk_index, u32 dst_session_index)
{
  u8 data[sizeof (u8) + sizeof (vls_sess_cleanup_msg_t)];
  vls_sess_cleanup_msg_t *msg;
  vls_rpc_msg_t *rpc;
  int ret;

  rpc = (vls_rpc_msg_t *) & data;
  rpc->type = VLS_RPC_SESS_CLEANUP;
  msg = (vls_sess_cleanup_msg_t *) & rpc->data;
  msg->origin_vcl_wrk = wrk->wrk_index;
  msg->session_index = dst_session_index;

  ret = vcl_send_worker_rpc (dst_wrk_index, rpc, sizeof (data));

  VDBG (1, "send session cleanup to wrk (session): %u (%u) from %u, ret=%d",
	dst_wrk_index, msg->session_index, msg->origin_vcl_wrk, ret);
}

int
vls_app_create (char *app_name)
{
  int rv;

  if ((rv = vppcom_app_create (app_name)))
    return rv;

  vlsm = clib_mem_alloc (sizeof (vls_main_t));
  clib_memset (vlsm, 0, sizeof (*vlsm));
  clib_rwlock_init (&vlsm->shared_data_lock);
  clib_spinlock_init (&vlsm->worker_rpc_lock);
  pool_alloc (vlsm->workers, vcm->cfg.max_workers);

  pthread_atfork (vls_app_pre_fork, vls_app_fork_parent_handler,
		  vls_app_fork_child_handler);
  atexit (vls_app_exit);
  vls_worker_alloc ();
  vlsl->vls_wrk_index = vcl_get_worker_index ();
  clib_rwlock_init (&vlsl->vls_pool_lock);
  vls_mt_locks_init ();
  vcm->wrk_rpc_fn = vls_rpc_handler;
  return VPPCOM_OK;
}

unsigned char
vls_use_eventfd (void)
{
  return vcm->cfg.use_mq_eventfd;
}

unsigned char
vls_mt_wrk_supported (void)
{
  return vcm->cfg.mt_wrk_supported;
}

int
vls_use_real_epoll (void)
{
  if (vcl_get_worker_index () == ~0)
    return 0;

  return vcl_worker_get_current ()->vcl_needs_real_epoll;
}

void
vls_register_vcl_worker (void)
{
  vls_mt_add ();
}

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */