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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * linux/net/sunrpc/svc.c
 *
 * High-level RPC service routines
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 *
 * Multiple threads pools and NUMAisation
 * Copyright (c) 2006 Silicon Graphics, Inc.
 * by Greg Banks <gnb@melbourne.sgi.com>
 */

#include <linux/linkage.h>
#include <linux/sched/signal.h>
#include <linux/errno.h>
#include <linux/net.h>
#include <linux/in.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/slab.h>

#include <linux/sunrpc/types.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/bc_xprt.h>

#include <trace/events/sunrpc.h>

#define RPCDBG_FACILITY	RPCDBG_SVCDSP

static void svc_unregister(const struct svc_serv *serv, struct net *net);

#define svc_serv_is_pooled(serv)    ((serv)->sv_ops->svo_function)

#define SVC_POOL_DEFAULT	SVC_POOL_GLOBAL

/*
 * Structure for mapping cpus to pools and vice versa.
 * Setup once during sunrpc initialisation.
 */
struct svc_pool_map svc_pool_map = {
	.mode = SVC_POOL_DEFAULT
};
EXPORT_SYMBOL_GPL(svc_pool_map);

static DEFINE_MUTEX(svc_pool_map_mutex);/* protects svc_pool_map.count only */

static int
param_set_pool_mode(const char *val, const struct kernel_param *kp)
{
	int *ip = (int *)kp->arg;
	struct svc_pool_map *m = &svc_pool_map;
	int err;

	mutex_lock(&svc_pool_map_mutex);

	err = -EBUSY;
	if (m->count)
		goto out;

	err = 0;
	if (!strncmp(val, "auto", 4))
		*ip = SVC_POOL_AUTO;
	else if (!strncmp(val, "global", 6))
		*ip = SVC_POOL_GLOBAL;
	else if (!strncmp(val, "percpu", 6))
		*ip = SVC_POOL_PERCPU;
	else if (!strncmp(val, "pernode", 7))
		*ip = SVC_POOL_PERNODE;
	else
		err = -EINVAL;

out:
	mutex_unlock(&svc_pool_map_mutex);
	return err;
}

static int
param_get_pool_mode(char *buf, const struct kernel_param *kp)
{
	int *ip = (int *)kp->arg;

	switch (*ip)
	{
	case SVC_POOL_AUTO:
		return strlcpy(buf, "auto", 20);
	case SVC_POOL_GLOBAL:
		return strlcpy(buf, "global", 20);
	case SVC_POOL_PERCPU:
		return strlcpy(buf, "percpu", 20);
	case SVC_POOL_PERNODE:
		return strlcpy(buf, "pernode", 20);
	default:
		return sprintf(buf, "%d", *ip);
	}
}

module_param_call(pool_mode, param_set_pool_mode, param_get_pool_mode,
		 &svc_pool_map.mode, 0644);

/*
 * Detect best pool mapping mode heuristically,
 * according to the machine's topology.
 */
static int
svc_pool_map_choose_mode(void)
{
	unsigned int node;

	if (nr_online_nodes > 1) {
		/*
		 * Actually have multiple NUMA nodes,
		 * so split pools on NUMA node boundaries
		 */
		return SVC_POOL_PERNODE;
	}

	node = first_online_node;
	if (nr_cpus_node(node) > 2) {
		/*
		 * Non-trivial SMP, or CONFIG_NUMA on
		 * non-NUMA hardware, e.g. with a generic
		 * x86_64 kernel on Xeons.  In this case we
		 * want to divide the pools on cpu boundaries.
		 */
		return SVC_POOL_PERCPU;
	}

	/* default: one global pool */
	return SVC_POOL_GLOBAL;
}

/*
 * Allocate the to_pool[] and pool_to[] arrays.
 * Returns 0 on success or an errno.
 */
static int
svc_pool_map_alloc_arrays(struct svc_pool_map *m, unsigned int maxpools)
{
	m->to_pool = kcalloc(maxpools, sizeof(unsigned int), GFP_KERNEL);
	if (!m->to_pool)
		goto fail;
	m->pool_to = kcalloc(maxpools, sizeof(unsigned int), GFP_KERNEL);
	if (!m->pool_to)
		goto fail_free;

	return 0;

fail_free:
	kfree(m->to_pool);
	m->to_pool = NULL;
fail:
	return -ENOMEM;
}

/*
 * Initialise the pool map for SVC_POOL_PERCPU mode.
 * Returns number of pools or <0 on error.
 */
static int
svc_pool_map_init_percpu(struct svc_pool_map *m)
{
	unsigned int maxpools = nr_cpu_ids;
	unsigned int pidx = 0;
	unsigned int cpu;
	int err;

	err = svc_pool_map_alloc_arrays(m, maxpools);
	if (err)
		return err;

	for_each_online_cpu(cpu) {
		BUG_ON(pidx >= maxpools);
		m->to_pool[cpu] = pidx;
		m->pool_to[pidx] = cpu;
		pidx++;
	}
	/* cpus brought online later all get mapped to pool0, sorry */

	return pidx;
};


/*
 * Initialise the pool map for SVC_POOL_PERNODE mode.
 * Returns number of pools or <0 on error.
 */
static int
svc_pool_map_init_pernode(struct svc_pool_map *m)
{
	unsigned int maxpools = nr_node_ids;
	unsigned int pidx = 0;
	unsigned int node;
	int err;

	err = svc_pool_map_alloc_arrays(m, maxpools);
	if (err)
		return err;

	for_each_node_with_cpus(node) {
		/* some architectures (e.g. SN2) have cpuless nodes */
		BUG_ON(pidx > maxpools);
		m->to_pool[node] = pidx;
		m->pool_to[pidx] = node;
		pidx++;
	}
	/* nodes brought online later all get mapped to pool0, sorry */

	return pidx;
}


/*
 * Add a reference to the global map of cpus to pools (and
 * vice versa).  Initialise the map if we're the first user.
 * Returns the number of pools.
 */
unsigned int
svc_pool_map_get(void)
{
	struct svc_pool_map *m = &svc_pool_map;
	int npools = -1;

	mutex_lock(&svc_pool_map_mutex);

	if (m->count++) {
		mutex_unlock(&svc_pool_map_mutex);
		return m->npools;
	}

	if (m->mode == SVC_POOL_AUTO)
		m->mode = svc_pool_map_choose_mode();

	switch (m->mode) {
	case SVC_POOL_PERCPU:
		npools = svc_pool_map_init_percpu(m);
		break;
	case SVC_POOL_PERNODE:
		npools = svc_pool_map_init_pernode(m);
		break;
	}

	if (npools < 0) {
		/* default, or memory allocation failure */
		npools = 1;
		m->mode = SVC_POOL_GLOBAL;
	}
	m->npools = npools;

	mutex_unlock(&svc_pool_map_mutex);
	return m->npools;
}
EXPORT_SYMBOL_GPL(svc_pool_map_get);

/*
 * Drop a reference to the global map of cpus to pools.
 * When the last reference is dropped, the map data is
 * freed; this allows the sysadmin to change the pool
 * mode using the pool_mode module option without
 * rebooting or re-loading sunrpc.ko.
 */
void
svc_pool_map_put(void)
{
	struct svc_pool_map *m = &svc_pool_map;

	mutex_lock(&svc_pool_map_mutex);

	if (!--m->count) {
		kfree(m->to_pool);
		m->to_pool = NULL;
		kfree(m->pool_to);
		m->pool_to = NULL;
		m->npools = 0;
	}

	mutex_unlock(&svc_pool_map_mutex);
}
EXPORT_SYMBOL_GPL(svc_pool_map_put);

static int svc_pool_map_get_node(unsigned int pidx)
{
	const struct svc_pool_map *m = &svc_pool_map;

	if (m->count) {
		if (m->mode == SVC_POOL_PERCPU)
			return cpu_to_node(m->pool_to[pidx]);
		if (m->mode == SVC_POOL_PERNODE)
			return m->pool_to[pidx];
	}
	return NUMA_NO_NODE;
}
/*
 * Set the given thread's cpus_allowed mask so that it
 * will only run on cpus in the given pool.
 */
static inline void
svc_pool_map_set_cpumask(struct task_struct *task, unsigned int pidx)
{
	struct svc_pool_map *m = &svc_pool_map;
	unsigned int node = m->pool_to[pidx];

	/*
	 * The caller checks for sv_nrpools > 1, which
	 * implies that we've been initialized.
	 */
	WARN_ON_ONCE(m->count == 0);
	if (m->count == 0)
		return;

	switch (m->mode) {
	case SVC_POOL_PERCPU:
	{
		set_cpus_allowed_ptr(task, cpumask_of(node));
		break;
	}
	case SVC_POOL_PERNODE:
	{
		set_cpus_allowed_ptr(task, cpumask_of_node(node));
		break;
	}
	}
}

/*
 * Use the mapping mode to choose a pool for a given CPU.
 * Used when enqueueing an incoming RPC.  Always returns
 * a non-NULL pool pointer.
 */
struct svc_pool *
svc_pool_for_cpu(struct svc_serv *serv, int cpu)
{
	struct svc_pool_map *m = &svc_pool_map;
	unsigned int pidx = 0;

	/*
	 * An uninitialised map happens in a pure client when
	 * lockd is brought up, so silently treat it the
	 * same as SVC_POOL_GLOBAL.
	 */
	if (svc_serv_is_pooled(serv)) {
		switch (m->mode) {
		case SVC_POOL_PERCPU:
			pidx = m->to_pool[cpu];
			break;
		case SVC_POOL_PERNODE:
			pidx = m->to_pool[cpu_to_node(cpu)];
			break;
		}
	}
	return &serv->sv_pools[pidx % serv->sv_nrpools];
}

int svc_rpcb_setup(struct svc_serv *serv, struct net *net)
{
	int err;

	err = rpcb_create_local(net);
	if (err)
		return err;

	/* Remove any stale portmap registrations */
	svc_unregister(serv, net);
	return 0;
}
EXPORT_SYMBOL_GPL(svc_rpcb_setup);

void svc_rpcb_cleanup(struct svc_serv *serv, struct net *net)
{
	svc_unregister(serv, net);
	rpcb_put_local(net);
}
EXPORT_SYMBOL_GPL(svc_rpcb_cleanup);

static int svc_uses_rpcbind(struct svc_serv *serv)
{
	struct svc_program	*progp;
	unsigned int		i;

	for (progp = serv->sv_program; progp; progp = progp->pg_next) {
		for (i = 0; i < progp->pg_nvers; i++) {
			if (progp->pg_vers[i] == NULL)
				continue;
			if (!progp->pg_vers[i]->vs_hidden)
				return 1;
		}
	}

	return 0;
}

int svc_bind(struct svc_serv *serv, struct net *net)
{
	if (!svc_uses_rpcbind(serv))
		return 0;
	return svc_rpcb_setup(serv, net);
}
EXPORT_SYMBOL_GPL(svc_bind);

#if defined(CONFIG_SUNRPC_BACKCHANNEL)
static void
__svc_init_bc(struct svc_serv *serv)
{
	INIT_LIST_HEAD(&serv->sv_cb_list);
	spin_lock_init(&serv->sv_cb_lock);
	init_waitqueue_head(&serv->sv_cb_waitq);
}
#else
static void
__svc_init_bc(struct svc_serv *serv)
{
}
#endif

/*
 * Create an RPC service
 */
static struct svc_serv *
__svc_create(struct svc_program *prog, unsigned int bufsize, int npools,
	     const struct svc_serv_ops *ops)
{
	struct svc_serv	*serv;
	unsigned int vers;
	unsigned int xdrsize;
	unsigned int i;

	if (!(serv = kzalloc(sizeof(*serv), GFP_KERNEL)))
		return NULL;
	serv->sv_name      = prog->pg_name;
	serv->sv_program   = prog;
	serv->sv_nrthreads = 1;
	serv->sv_stats     = prog->pg_stats;
	if (bufsize > RPCSVC_MAXPAYLOAD)
		bufsize = RPCSVC_MAXPAYLOAD;
	serv->sv_max_payload = bufsize? bufsize : 4096;
	serv->sv_max_mesg  = roundup(serv->sv_max_payload + PAGE_SIZE, PAGE_SIZE);
	serv->sv_ops = ops;
	xdrsize = 0;
	while (prog) {
		prog->pg_lovers = prog->pg_nvers-1;
		for (vers=0; vers<prog->pg_nvers ; vers++)
			if (prog->pg_vers[vers]) {
				prog->pg_hivers = vers;
				if (prog->pg_lovers > vers)
					prog->pg_lovers = vers;
				if (prog->pg_vers[vers]->vs_xdrsize > xdrsize)
					xdrsize = prog->pg_vers[vers]->vs_xdrsize;
			}
		prog = prog->pg_next;
	}
	serv->sv_xdrsize   = xdrsize;
	INIT_LIST_HEAD(&serv->sv_tempsocks);
	INIT_LIST_HEAD(&serv->sv_permsocks);
	timer_setup(&serv->sv_temptimer, NULL, 0);
	spin_lock_init(&serv->sv_lock);

	__svc_init_bc(serv);

	serv->sv_nrpools = npools;
	serv->sv_pools =
		kcalloc(serv->sv_nrpools, sizeof(struct svc_pool),
			GFP_KERNEL);
	if (!serv->sv_pools) {
		kfree(serv);
		return NULL;
	}

	for (i = 0; i < serv->sv_nrpools; i++) {
		struct svc_pool *pool = &serv->sv_pools[i];

		dprintk("svc: initialising pool %u for %s\n",
				i, serv->sv_name);

		pool->sp_id = i;
		INIT_LIST_HEAD(&pool->sp_sockets);
		INIT_LIST_HEAD(&pool->sp_all_threads);
		spin_lock_init(&pool->sp_lock);
	}

	return serv;
}

struct svc_serv *
svc_create(struct svc_program *prog, unsigned int bufsize,
	   const struct svc_serv_ops *ops)
{
	return __svc_create(prog, bufsize, /*npools*/1, ops);
}
EXPORT_SYMBOL_GPL(svc_create);

struct svc_serv *
svc_create_pooled(struct svc_program *prog, unsigned int bufsize,
		  const struct svc_serv_ops *ops)
{
	struct svc_serv *serv;
	unsigned int npools = svc_pool_map_get();

	serv = __svc_create(prog, bufsize, npools, ops);
	if (!serv)
		goto out_err;
	return serv;
out_err:
	svc_pool_map_put();
	return NULL;
}
EXPORT_SYMBOL_GPL(svc_create_pooled);

void svc_shutdown_net(struct svc_serv *serv, struct net *net)
{
	svc_close_net(serv, net);

	if (serv->sv_ops->svo_shutdown)
		serv->sv_ops->svo_shutdown(serv, net);
}
EXPORT_SYMBOL_GPL(svc_shutdown_net);

/*
 * Destroy an RPC service. Should be called with appropriate locking to
 * protect the sv_nrthreads, sv_permsocks and sv_tempsocks.
 */
void
svc_destroy(struct svc_serv *serv)
{
	dprintk("svc: svc_destroy(%s, %d)\n",
				serv->sv_program->pg_name,
				serv->sv_nrthreads);

	if (serv->sv_nrthreads) {
		if (--(serv->sv_nrthreads) != 0) {
			svc_sock_update_bufs(serv);
			return;
		}
	} else
		printk("svc_destroy: no threads for serv=%p!\n", serv);

	del_timer_sync(&serv->sv_temptimer);

	/*
	 * The last user is gone and thus all sockets have to be destroyed to
	 * the point. Check this.
	 */
	BUG_ON(!list_empty(&serv->sv_permsocks));
	BUG_ON(!list_empty(&serv->sv_tempsocks));

	cache_clean_deferred(serv);

	if (svc_serv_is_pooled(serv))
		svc_pool_map_put();

	kfree(serv->sv_pools);
	kfree(serv);
}
EXPORT_SYMBOL_GPL(svc_destroy);

/*
 * Allocate an RPC server's buffer space.
 * We allocate pages and place them in rq_argpages.
 */
static int
svc_init_buffer(struct svc_rqst *rqstp, unsigned int size, int node)
{
	unsigned int pages, arghi;

	/* bc_xprt uses fore channel allocated buffers */
	if (svc_is_backchannel(rqstp))
		return 1;

	pages = size / PAGE_SIZE + 1; /* extra page as we hold both request and reply.
				       * We assume one is at most one page
				       */
	arghi = 0;
	WARN_ON_ONCE(pages > RPCSVC_MAXPAGES);
	if (pages > RPCSVC_MAXPAGES)
		pages = RPCSVC_MAXPAGES;
	while (pages) {
		struct page *p = alloc_pages_node(node, GFP_KERNEL, 0);
		if (!p)
			break;
		rqstp->rq_pages[arghi++] = p;
		pages--;
	}
	return pages == 0;
}

/*
 * Release an RPC server buffer
 */
static void
svc_release_buffer(struct svc_rqst *rqstp)
{
	unsigned int i;

	for (i = 0; i < ARRAY_SIZE(rqstp->rq_pages); i++)
		if (rqstp->rq_pages[i])
			put_page(rqstp->rq_pages[i]);
}

struct svc_rqst *
svc_rqst_alloc(struct svc_serv *serv, struct svc_pool *pool, int node)
{
	struct svc_rqst	*rqstp;

	rqstp = kzalloc_node(sizeof(*rqstp), GFP_KERNEL, node);
	if (!rqstp)
		return rqstp;

	__set_bit(RQ_BUSY, &rqstp->rq_flags);
	spin_lock_init(&rqstp->rq_lock);
	rqstp->rq_server = serv;
	rqstp->rq_pool = pool;

	rqstp->rq_argp = kmalloc_node(serv->sv_xdrsize, GFP_KERNEL, node);
	if (!rqstp->rq_argp)
		goto out_enomem;

	rqstp->rq_resp = kmalloc_node(serv->sv_xdrsize, GFP_KERNEL, node);
	if (!rqstp->rq_resp)
		goto out_enomem;

	if (!svc_init_buffer(rqstp, serv->sv_max_mesg, node))
		goto out_enomem;

	return rqstp;
out_enomem:
	svc_rqst_free(rqstp);
	return NULL;
}
EXPORT_SYMBOL_GPL(svc_rqst_alloc);

struct svc_rqst *
svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node)
{
	struct svc_rqst	*rqstp;

	rqstp = svc_rqst_alloc(serv, pool, node);
	if (!rqstp)
		return ERR_PTR(-ENOMEM);

	serv->sv_nrthreads++;
	spin_lock_bh(&pool->sp_lock);
	pool->sp_nrthreads++;
	list_add_rcu(&rqstp->rq_all, &pool->sp_all_threads);
	spin_unlock_bh(&pool->sp_lock);
	return rqstp;
}
EXPORT_SYMBOL_GPL(svc_prepare_thread);

/*
 * Choose a pool in which to create a new thread, for svc_set_num_threads
 */
static inline struct svc_pool *
choose_pool(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)
{
	if (pool != NULL)
		return pool;

	return &serv->sv_pools[(*state)++ % serv->sv_nrpools];
}

/*
 * Choose a thread to kill, for svc_set_num_threads
 */
static inline struct task_struct *
choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)
{
	unsigned int i;
	struct task_struct *task = NULL;

	if (pool != NULL) {
		spin_lock_bh(&pool->sp_lock);
	} else {
		/* choose a pool in round-robin fashion */
		for (i = 0; i < serv->sv_nrpools; i++) {
			pool = &serv->sv_pools[--(*state) % serv->sv_nrpools];
			spin_lock_bh(&pool->sp_lock);
			if (!list_empty(&pool->sp_all_threads))
				goto found_pool;
			spin_unlock_bh(&pool->sp_lock);
		}
		return NULL;
	}

found_pool:
	if (!list_empty(&pool->sp_all_threads)) {
		struct svc_rqst *rqstp;

		/*
		 * Remove from the pool->sp_all_threads list
		 * so we don't try to kill it again.
		 */
		rqstp = list_entry(pool->sp_all_threads.next, struct svc_rqst, rq_all);
		set_bit(RQ_VICTIM, &rqstp->rq_flags);
		list_del_rcu(&rqstp->rq_all);
		task = rqstp->rq_task;
	}
	spin_unlock_bh(&pool->sp_lock);

	return task;
}

/* create new threads */
static int
svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{
	struct svc_rqst	*rqstp;
	struct task_struct *task;
	struct svc_pool *chosen_pool;
	unsigned int state = serv->sv_nrthreads-1;
	int node;

	do {
		nrservs--;
		chosen_pool = choose_pool(serv, pool, &state);

		node = svc_pool_map_get_node(chosen_pool->sp_id);
		rqstp = svc_prepare_thread(serv, chosen_pool, node);
		if (IS_ERR(rqstp))
			return PTR_ERR(rqstp);

		__module_get(serv->sv_ops->svo_module);
		task = kthread_create_on_node(serv->sv_ops->svo_function, rqstp,
					      node, "%s", serv->sv_name);
		if (IS_ERR(task)) {
			module_put(serv->sv_ops->svo_module);
			svc_exit_thread(rqstp);
			return PTR_ERR(task);
		}

		rqstp->rq_task = task;
		if (serv->sv_nrpools > 1)
			svc_pool_map_set_cpumask(task, chosen_pool->sp_id);

		svc_sock_update_bufs(serv);
		wake_up_process(task);
	} while (nrservs > 0);

	return 0;
}


/* destroy old threads */
static int
svc_signal_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{
	struct task_struct *task;
	unsigned int state = serv->sv_nrthreads-1;

	/* destroy old threads */
	do {
		task = choose_victim(serv, pool, &state);
		if (task == NULL)
			break;
		send_sig(SIGINT, task, 1);
		nrservs++;
	} while (nrservs < 0);

	return 0;
}

/*
 * Create or destroy enough new threads to make the number
 * of threads the given number.  If `pool' is non-NULL, applies
 * only to threads in that pool, otherwise round-robins between
 * all pools.  Caller must ensure that mutual exclusion between this and
 * server startup or shutdown.
 *
 * Destroying threads relies on the service threads filling in
 * rqstp->rq_task, which only the nfs ones do.  Assumes the serv
 * has been created using svc_create_pooled().
 *
 * Based on code that used to be in nfsd_svc() but tweaked
 * to be pool-aware.
 */
int
svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{
	if (pool == NULL) {
		/* The -1 assumes caller has done a svc_get() */
		nrservs -= (serv->sv_nrthreads-1);
	} else {
		spin_lock_bh(&pool->sp_lock);
		nrservs -= pool->sp_nrthreads;
		spin_unlock_bh(&pool->sp_lock);
	}

	if (nrservs > 0)
		return svc_start_kthreads(serv, pool, nrservs);
	if (nrservs < 0)
		return svc_signal_kthreads(serv, pool, nrservs);
	return 0;
}
EXPORT_SYMBOL_GPL(svc_set_num_threads);

/* destroy old threads */
static int
svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{
	struct task_struct *task;
	unsigned int state = serv->sv_nrthreads-1;

	/* destroy old threads */
	do {
		task = choose_victim(serv, pool, &state);
		if (task == NULL)
			break;
		kthread_stop(task);
		nrservs++;
	} while (nrservs < 0);
	return 0;
}

int
svc_set_num_threads_sync(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{
	if (pool == NULL) {
		/* The -1 assumes caller has done a svc_get() */
		nrservs -= (serv->sv_nrthreads-1);
	} else {
		spin_lock_bh(&pool->sp_lock);
		nrservs -= pool->sp_nrthreads;
		spin_unlock_bh(&pool->sp_lock);
	}

	if (nrservs > 0)
		return svc_start_kthreads(serv, pool, nrservs);
	if (nrservs < 0)
		return svc_stop_kthreads(serv, pool, nrservs);
	return 0;
}
EXPORT_SYMBOL_GPL(svc_set_num_threads_sync);

/*
 * Called from a server thread as it's exiting. Caller must hold the "service
 * mutex" for the service.
 */
void
svc_rqst_free(struct svc_rqst *rqstp)
{
	svc_release_buffer(rqstp);
	kfree(rqstp->rq_resp);
	kfree(rqstp->rq_argp);
	kfree(rqstp->rq_auth_data);
	kfree_rcu(rqstp, rq_rcu_head);
}
EXPORT_SYMBOL_GPL(svc_rqst_free);

void
svc_exit_thread(struct svc_rqst *rqstp)
{
	struct svc_serv	*serv = rqstp->rq_server;
	struct svc_pool	*pool = rqstp->rq_pool;

	spin_lock_bh(&pool->sp_lock);
	pool->sp_nrthreads--;
	if (!test_and_set_bit(RQ_VICTIM, &rqstp->rq_flags))
		list_del_rcu(&rqstp->rq_all);
	spin_unlock_bh(&pool->sp_lock);

	svc_rqst_free(rqstp);

	/* Release the server */
	if (serv)
		svc_destroy(serv);
}
EXPORT_SYMBOL_GPL(svc_exit_thread);

/*
 * Register an "inet" protocol family netid with the local
 * rpcbind daemon via an rpcbind v4 SET request.
 *
 * No netconfig infrastructure is available in the kernel, so
 * we map IP_ protocol numbers to netids by hand.
 *
 * Returns zero on success; a negative errno value is returned
 * if any error occurs.
 */
static int __svc_rpcb_register4(struct net *net, const u32 program,
				const u32 version,
				const unsigned short protocol,
				const unsigned short port)
{
	const struct sockaddr_in sin = {
		.sin_family		= AF_INET,
		.sin_addr.s_addr	= htonl(INADDR_ANY),
		.sin_port		= htons(port),
	};
	const char *netid;
	int error;

	switch (protocol) {
	case IPPROTO_UDP:
		netid = RPCBIND_NETID_UDP;
		break;
	case IPPROTO_TCP:
		netid = RPCBIND_NETID_TCP;
		break;
	default:
		return -ENOPROTOOPT;
	}

	error = rpcb_v4_register(net, program, version,
					(const struct sockaddr *)&sin, netid);

	/*
	 * User space didn't support rpcbind v4, so retry this
	 * registration request with the legacy rpcbind v2 protocol.
	 */
	if (error == -EPROTONOSUPPORT)
		error = rpcb_register(net, program, version, protocol, port);

	return error;
}

#if IS_ENABLED(CONFIG_IPV6)
/*
 * Register an "inet6" protocol family netid with the local
 * rpcbind daemon via an rpcbind v4 SET request.
 *
 * No netconfig infrastructure is available in the kernel, so
 * we map IP_ protocol numbers to netids by hand.
 *
 * Returns zero on success; a negative errno value is returned
 * if any error occurs.
 */
static int __svc_rpcb_register6(struct net *net, const u32 program,
				const u32 version,
				const unsigned short protocol,
				const unsigned short port)
{
	const struct sockaddr_in6 sin6 = {
		.sin6_family		= AF_INET6,
		.sin6_addr		= IN6ADDR_ANY_INIT,
		.sin6_port		= htons(port),
	};
	const char *netid;
	int error;

	switch (protocol) {
	case IPPROTO_UDP:
		netid = RPCBIND_NETID_UDP6;
		break;
	case IPPROTO_TCP:
		netid = RPCBIND_NETID_TCP6;
		break;
	default:
		return -ENOPROTOOPT;
	}

	error = rpcb_v4_register(net, program, version,
					(const struct sockaddr *)&sin6, netid);

	/*
	 * User space didn't support rpcbind version 4, so we won't
	 * use a PF_INET6 listener.
	 */
	if (error == -EPROTONOSUPPORT)
		error = -EAFNOSUPPORT;

	return error;
}
#endif	/* IS_ENABLED(CONFIG_IPV6) */

/*
 * Register a kernel RPC service via rpcbind version 4.
 *
 * Returns zero on success; a negative errno value is returned
 * if any error occurs.
 */
static int __svc_register(struct net *net, const char *progname,
			  const u32 program, const u32 version,
			  const int family,
			  const unsigned short protocol,
			  const unsigned short port)
{
	int error = -EAFNOSUPPORT;

	switch (family) {
	case PF_INET:
		error = __svc_rpcb_register4(net, program, version,
						protocol, port);
		break;
#if IS_ENABLED(CONFIG_IPV6)
	case PF_INET6:
		error = __svc_rpcb_register6(net, program, version,
						protocol, port);
#endif
	}

	return error;
}

int svc_rpcbind_set_version(struct net *net,
			    const struct svc_program *progp,
			    u32 version, int family,
			    unsigned short proto,
			    unsigned short port)
{
	dprintk("svc: svc_register(%sv%d, %s, %u, %u)\n",
		progp->pg_name, version,
		proto == IPPROTO_UDP?  "udp" : "tcp",
		port, family);

	return __svc_register(net, progp->pg_name, progp->pg_prog,
				version, family, proto, port);

}
EXPORT_SYMBOL_GPL(svc_rpcbind_set_version);

int svc_generic_rpcbind_set(struct net *net,
			    const struct svc_program *progp,
			    u32 version, int family,
			    unsigned short proto,
			    unsigned short port)
{
	const struct svc_version *vers = progp->pg_vers[version];
	int error;

	if (vers == NULL)
		return 0;

	if (vers->vs_hidden) {
		dprintk("svc: svc_register(%sv%d, %s, %u, %u)"
			" (but not telling portmap)\n",
			progp->pg_name, version,
			proto == IPPROTO_UDP?  "udp" : "tcp",
			port, family);
		return 0;
	}

	/*
	 * Don't register a UDP port if we need congestion
	 * control.
	 */
	if (vers->vs_need_cong_ctrl && proto == IPPROTO_UDP)
		return 0;

	error = svc_rpcbind_set_version(net, progp, version,
					family, proto, port);

	return (vers->vs_rpcb_optnl) ? 0 : error;
}
EXPORT_SYMBOL_GPL(svc_generic_rpcbind_set);

/**
 * svc_register - register an RPC service with the local portmapper
 * @serv: svc_serv struct for the service to register
 * @net: net namespace for the service to register
 * @family: protocol family of service's listener socket
 * @proto: transport protocol number to advertise
 * @port: port to advertise
 *
 * Service is registered for any address in the passed-in protocol family
 */
int svc_register(const struct svc_serv *serv, struct net *net,
		 const int family, const unsigned short proto,
		 const unsigned short port)
{
	struct svc_program	*progp;
	unsigned int		i;
	int			error = 0;

	WARN_ON_ONCE(proto == 0 && port == 0);
	if (proto == 0 && port == 0)
		return -EINVAL;

	for (progp = serv->sv_program; progp; progp = progp->pg_next) {
		for (i = 0; i < progp->pg_nvers; i++) {

			error = progp->pg_rpcbind_set(net, progp, i,
					family, proto, port);
			if (error < 0) {
				printk(KERN_WARNING "svc: failed to register "
					"%sv%u RPC service (errno %d).\n",
					progp->pg_name, i, -error);
				break;
			}
		}
	}

	return error;
}

/*
 * If user space is running rpcbind, it should take the v4 UNSET
 * and clear everything for this [program, version].  If user space
 * is running portmap, it will reject the v4 UNSET, but won't have
 * any "inet6" entries anyway.  So a PMAP_UNSET should be sufficient
 * in this case to clear all existing entries for [program, version].
 */
static void __svc_unregister(struct net *net, const u32 program, const u32 version,
			     const char *progname)
{
	int error;

	error = rpcb_v4_register(net, program, version, NULL, "");

	/*
	 * User space didn't support rpcbind v4, so retry this
	 * request with the legacy rpcbind v2 protocol.
	 */
	if (error == -EPROTONOSUPPORT)
		error = rpcb_register(net, program, version, 0, 0);

	dprintk("svc: %s(%sv%u), error %d\n",
			__func__, progname, version, error);
}

/*
 * All netids, bind addresses and ports registered for [program, version]
 * are removed from the local rpcbind database (if the service is not
 * hidden) to make way for a new instance of the service.
 *
 * The result of unregistration is reported via dprintk for those who want
 * verification of the result, but is otherwise not important.
 */
static void svc_unregister(const struct svc_serv *serv, struct net *net)
{
	struct svc_program *progp;
	unsigned long flags;
	unsigned int i;

	clear_thread_flag(TIF_SIGPENDING);

	for (progp = serv->sv_program; progp; progp = progp->pg_next) {
		for (i = 0; i < progp->pg_nvers; i++) {
			if (progp->pg_vers[i] == NULL)
				continue;
			if (progp->pg_vers[i]->vs_hidden)
				continue;

			dprintk("svc: attempting to unregister %sv%u\n",
				progp->pg_name, i);
			__svc_unregister(net, progp->pg_prog, i, progp->pg_name);
		}
	}

	spin_lock_irqsave(&current->sighand->siglock, flags);
	recalc_sigpending();
	spin_unlock_irqrestore(&current->sighand->siglock, flags);
}

/*
 * dprintk the given error with the address of the client that caused it.
 */
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
static __printf(2, 3)
void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...)
{
	struct va_format vaf;
	va_list args;
	char 	buf[RPC_MAX_ADDRBUFLEN];

	va_start(args, fmt);

	vaf.fmt = fmt;
	vaf.va = &args;

	dprintk("svc: %s: %pV", svc_print_addr(rqstp, buf, sizeof(buf)), &vaf);

	va_end(args);
}
#else
static __printf(2,3) void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...) {}
#endif

__be32
svc_return_autherr(struct svc_rqst *rqstp, __be32 auth_err)
{
	set_bit(RQ_AUTHERR, &rqstp->rq_flags);
	return auth_err;
}
EXPORT_SYMBOL_GPL(svc_return_autherr);

static __be32
svc_get_autherr(struct svc_rqst *rqstp, __be32 *statp)
{
	if (test_and_clear_bit(RQ_AUTHERR, &rqstp->rq_flags))
		return *statp;
	return rpc_auth_ok;
}

static int
svc_generic_dispatch(struct svc_rqst *rqstp, __be32 *statp)
{
	struct kvec *argv = &rqstp->rq_arg.head[0];
	struct kvec *resv = &rqstp->rq_res.head[0];
	const struct svc_procedure *procp = rqstp->rq_procinfo;

	/*
	 * Decode arguments
	 * XXX: why do we ignore the return value?
	 */
	if (procp->pc_decode &&
	    !procp->pc_decode(rqstp, argv->iov_base)) {
		*statp = rpc_garbage_args;
		return 1;
	}

	*statp = procp->pc_func(rqstp);

	if (*statp == rpc_drop_reply ||
	    test_bit(RQ_DROPME, &rqstp->rq_flags))
		return 0;

	if (test_bit(RQ_AUTHERR, &rqstp->rq_flags))
		return 1;

	if (*statp != rpc_success)
		return 1;

	/* Encode reply */
	if (procp->pc_encode &&
	    !procp->pc_encode(rqstp, resv->iov_base + resv->iov_len)) {
		dprintk("svc: failed to encode reply\n");
		/* serv->sv_stats->rpcsystemerr++; */
		*statp = rpc_system_err;
	}
	return 1;
}

__be32
svc_generic_init_request(struct svc_rqst *rqstp,
		const struct svc_program *progp,
		struct svc_process_info *ret)
{
	const struct svc_version *versp = NULL;	/* compiler food */
	const struct svc_procedure *procp = NULL;

	if (rqstp->rq_vers >= progp->pg_nvers )
		goto err_bad_vers;
	versp = progp->pg_vers[rqstp->rq_vers];
	if (!versp)
		goto err_bad_vers;

	/*
	 * Some protocol versions (namely NFSv4) require some form of
	 * congestion control.  (See RFC 7530 section 3.1 paragraph 2)
	 * In other words, UDP is not allowed. We mark those when setting
	 * up the svc_xprt, and verify that here.
	 *
	 * The spec is not very clear about what error should be returned
	 * when someone tries to access a server that is listening on UDP
	 * for lower versions. RPC_PROG_MISMATCH seems to be the closest
	 * fit.
	 */
	if (versp->vs_need_cong_ctrl && rqstp->rq_xprt &&
	    !test_bit(XPT_CONG_CTRL, &rqstp->rq_xprt->xpt_flags))
		goto err_bad_vers;

	if (rqstp->rq_proc >= versp->vs_nproc)
		goto err_bad_proc;
	rqstp->rq_procinfo = procp = &versp->vs_proc[rqstp->rq_proc];
	if (!procp)
		goto err_bad_proc;

	/* Initialize storage for argp and resp */
	memset(rqstp->rq_argp, 0, procp->pc_argsize);
	memset(rqstp->rq_resp, 0, procp->pc_ressize);

	/* Bump per-procedure stats counter */
	versp->vs_count[rqstp->rq_proc]++;

	ret->dispatch = versp->vs_dispatch;
	return rpc_success;
err_bad_vers:
	ret->mismatch.lovers = progp->pg_lovers;
	ret->mismatch.hivers = progp->pg_hivers;
	return rpc_prog_mismatch;
err_bad_proc:
	return rpc_proc_unavail;
}
EXPORT_SYMBOL_GPL(svc_generic_init_request);

/*
 * Common routine for processing the RPC request.
 */
static int
svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
{
	struct svc_program	*progp;
	const struct svc_procedure *procp = NULL;
	struct svc_serv		*serv = rqstp->rq_server;
	struct svc_process_info process;
	__be32			*statp;
	u32			prog, vers;
	__be32			auth_stat, rpc_stat;
	int			auth_res;
	__be32			*reply_statp;

	rpc_stat = rpc_success;

	if (argv->iov_len < 6*4)
		goto err_short_len;

	/* Will be turned off by GSS integrity and privacy services */
	set_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
	/* Will be turned off only when NFSv4 Sessions are used */
	set_bit(RQ_USEDEFERRAL, &rqstp->rq_flags);
	clear_bit(RQ_DROPME, &rqstp->rq_flags);

	svc_putu32(resv, rqstp->rq_xid);

	vers = svc_getnl(argv);

	/* First words of reply: */
	svc_putnl(resv, 1);		/* REPLY */

	if (vers != 2)		/* RPC version number */
		goto err_bad_rpc;

	/* Save position in case we later decide to reject: */
	reply_statp = resv->iov_base + resv->iov_len;

	svc_putnl(resv, 0);		/* ACCEPT */

	rqstp->rq_prog = prog = svc_getnl(argv);	/* program number */
	rqstp->rq_vers = svc_getnl(argv);	/* version number */
	rqstp->rq_proc = svc_getnl(argv);	/* procedure number */

	for (progp = serv->sv_program; progp; progp = progp->pg_next)
		if (prog == progp->pg_prog)
			break;

	/*
	 * Decode auth data, and add verifier to reply buffer.
	 * We do this before anything else in order to get a decent
	 * auth verifier.
	 */
	auth_res = svc_authenticate(rqstp, &auth_stat);
	/* Also give the program a chance to reject this call: */
	if (auth_res == SVC_OK && progp) {
		auth_stat = rpc_autherr_badcred;
		auth_res = progp->pg_authenticate(rqstp);
	}
	switch (auth_res) {
	case SVC_OK:
		break;
	case SVC_GARBAGE:
		goto err_garbage;
	case SVC_SYSERR:
		rpc_stat = rpc_system_err;
		goto err_bad;
	case SVC_DENIED:
		goto err_bad_auth;
	case SVC_CLOSE:
		goto close;
	case SVC_DROP:
		goto dropit;
	case SVC_COMPLETE:
		goto sendit;
	}

	if (progp == NULL)
		goto err_bad_prog;

	rpc_stat = progp->pg_init_request(rqstp, progp, &process);
	switch (rpc_stat) {
	case rpc_success:
		break;
	case rpc_prog_unavail:
		goto err_bad_prog;
	case rpc_prog_mismatch:
		goto err_bad_vers;
	case rpc_proc_unavail:
		goto err_bad_proc;
	}

	procp = rqstp->rq_procinfo;
	/* Should this check go into the dispatcher? */
	if (!procp || !procp->pc_func)
		goto err_bad_proc;

	/* Syntactic check complete */
	serv->sv_stats->rpccnt++;
	trace_svc_process(rqstp, progp->pg_name);

	/* Build the reply header. */
	statp = resv->iov_base +resv->iov_len;
	svc_putnl(resv, RPC_SUCCESS);

	/* un-reserve some of the out-queue now that we have a
	 * better idea of reply size
	 */
	if (procp->pc_xdrressize)
		svc_reserve_auth(rqstp, procp->pc_xdrressize<<2);

	/* Call the function that processes the request. */
	if (!process.dispatch) {
		if (!svc_generic_dispatch(rqstp, statp))
			goto release_dropit;
		if (*statp == rpc_garbage_args)
			goto err_garbage;
		auth_stat = svc_get_autherr(rqstp, statp);
		if (auth_stat != rpc_auth_ok)
			goto err_release_bad_auth;
	} else {
		dprintk("svc: calling dispatcher\n");
		if (!process.dispatch(rqstp, statp))
			goto release_dropit; /* Release reply info */
	}

	/* Check RPC status result */
	if (*statp != rpc_success)
		resv->iov_len = ((void*)statp)  - resv->iov_base + 4;

	/* Release reply info */
	if (procp->pc_release)
		procp->pc_release(rqstp);

	if (procp->pc_encode == NULL)
		goto dropit;

 sendit:
	if (svc_authorise(rqstp))
		goto close;
	return 1;		/* Caller can now send it */

release_dropit:
	if (procp->pc_release)
		procp->pc_release(rqstp);
 dropit:
	svc_authorise(rqstp);	/* doesn't hurt to call this twice */
	dprintk("svc: svc_process dropit\n");
	return 0;

 close:
	if (rqstp->rq_xprt && test_bit(XPT_TEMP, &rqstp->rq_xprt->xpt_flags))
		svc_close_xprt(rqstp->rq_xprt);
	dprintk("svc: svc_process close\n");
	return 0;

err_short_len:
	svc_printk(rqstp, "short len %zd, dropping request\n",
			argv->iov_len);
	goto close;

err_bad_rpc:
	serv->sv_stats->rpcbadfmt++;
	svc_putnl(resv, 1);	/* REJECT */
	svc_putnl(resv, 0);	/* RPC_MISMATCH */
	svc_putnl(resv, 2);	/* Only RPCv2 supported */
	svc_putnl(resv, 2);
	goto sendit;

err_release_bad_auth:
	if (procp->pc_release)
		procp->pc_release(rqstp);
err_bad_auth:
	dprintk("svc: authentication failed (%d)\n", ntohl(auth_stat));
	serv->sv_stats->rpcbadauth++;
	/* Restore write pointer to location of accept status: */
	xdr_ressize_check(rqstp, reply_statp);
	svc_putnl(resv, 1);	/* REJECT */
	svc_putnl(resv, 1);	/* AUTH_ERROR */
	svc_putnl(resv, ntohl(auth_stat));	/* status */
	goto sendit;

err_bad_prog:
	dprintk("svc: unknown program %d\n", prog);
	serv->sv_stats->rpcbadfmt++;
	svc_putnl(resv, RPC_PROG_UNAVAIL);
	goto sendit;

err_bad_vers:
	svc_printk(rqstp, "unknown version (%d for prog %d, %s)\n",
		       rqstp->rq_vers, rqstp->rq_prog, progp->pg_name);

	serv->sv_stats->rpcbadfmt++;
	svc_putnl(resv, RPC_PROG_MISMATCH);
	svc_putnl(resv, process.mismatch.lovers);
	svc_putnl(resv, process.mismatch.hivers);
	goto sendit;

err_bad_proc:
	svc_printk(rqstp, "unknown procedure (%d)\n", rqstp->rq_proc);

	serv->sv_stats->rpcbadfmt++;
	svc_putnl(resv, RPC_PROC_UNAVAIL);
	goto sendit;

err_garbage:
	svc_printk(rqstp, "failed to decode args\n");

	rpc_stat = rpc_garbage_args;
err_bad:
	serv->sv_stats->rpcbadfmt++;
	svc_putnl(resv, ntohl(rpc_stat));
	goto sendit;
}

/*
 * Process the RPC request.
 */
int
svc_process(struct svc_rqst *rqstp)
{
	struct kvec		*argv = &rqstp->rq_arg.head[0];
	struct kvec		*resv = &rqstp->rq_res.head[0];
	struct svc_serv		*serv = rqstp->rq_server;
	u32			dir;

	/*
	 * Setup response xdr_buf.
	 * Initially it has just one page
	 */
	rqstp->rq_next_page = &rqstp->rq_respages[1];
	resv->iov_base = page_address(rqstp->rq_respages[0]);
	resv->iov_len = 0;
	rqstp->rq_res.pages = rqstp->rq_respages + 1;
	rqstp->rq_res.len = 0;
	rqstp->rq_res.page_base = 0;
	rqstp->rq_res.page_len = 0;
	rqstp->rq_res.buflen = PAGE_SIZE;
	rqstp->rq_res.tail[0].iov_base = NULL;
	rqstp->rq_res.tail[0].iov_len = 0;

	dir  = svc_getnl(argv);
	if (dir != 0) {
		/* direction != CALL */
		svc_printk(rqstp, "bad direction %d, dropping request\n", dir);
		serv->sv_stats->rpcbadfmt++;
		goto out_drop;
	}

	/* Reserve space for the record marker */
	if (rqstp->rq_prot == IPPROTO_TCP)
		svc_putnl(resv, 0);

	/* Returns 1 for send, 0 for drop */
	if (likely(svc_process_common(rqstp, argv, resv)))
		return svc_send(rqstp);

out_drop:
	svc_drop(rqstp);
	return 0;
}
EXPORT_SYMBOL_GPL(svc_process);

#if defined(CONFIG_SUNRPC_BACKCHANNEL)
/*
 * Process a backchannel RPC request that arrived over an existing
 * outbound connection
 */
int
bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req,
	       struct svc_rqst *rqstp)
{
	struct kvec	*argv = &rqstp->rq_arg.head[0];
	struct kvec	*resv = &rqstp->rq_res.head[0];
	struct rpc_task *task;
	int proc_error;
	int error;

	dprintk("svc: %s(%p)\n", __func__, req);

	/* Build the svc_rqst used by the common processing routine */
	rqstp->rq_xid = req->rq_xid;
	rqstp->rq_prot = req->rq_xprt->prot;
	rqstp->rq_server = serv;
	rqstp->rq_bc_net = req->rq_xprt->xprt_net;

	rqstp->rq_addrlen = sizeof(req->rq_xprt->addr);
	memcpy(&rqstp->rq_addr, &req->rq_xprt->addr, rqstp->rq_addrlen);
	memcpy(&rqstp->rq_arg, &req->rq_rcv_buf, sizeof(rqstp->rq_arg));
	memcpy(&rqstp->rq_res, &req->rq_snd_buf, sizeof(rqstp->rq_res));

	/* Adjust the argument buffer length */
	rqstp->rq_arg.len = req->rq_private_buf.len;
	if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len) {
		rqstp->rq_arg.head[0].iov_len = rqstp->rq_arg.len;
		rqstp->rq_arg.page_len = 0;
	} else if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len +
			rqstp->rq_arg.page_len)
		rqstp->rq_arg.page_len = rqstp->rq_arg.len -
			rqstp->rq_arg.head[0].iov_len;
	else
		rqstp->rq_arg.len = rqstp->rq_arg.head[0].iov_len +
			rqstp->rq_arg.page_len;

	/* reset result send buffer "put" position */
	resv->iov_len = 0;

	/*
	 * Skip the next two words because they've already been
	 * processed in the transport
	 */
	svc_getu32(argv);	/* XID */
	svc_getnl(argv);	/* CALLDIR */

	/* Parse and execute the bc call */
	proc_error = svc_process_common(rqstp, argv, resv);

	atomic_dec(&req->rq_xprt->bc_slot_count);
	if (!proc_error) {
		/* Processing error: drop the request */
		xprt_free_bc_request(req);
		error = -EINVAL;
		goto out;
	}
	/* Finally, send the reply synchronously */
	memcpy(&req->rq_snd_buf, &rqstp->rq_res, sizeof(req->rq_snd_buf));
	task = rpc_run_bc_task(req);
	if (IS_ERR(task)) {
		error = PTR_ERR(task);
		goto out;
	}

	WARN_ON_ONCE(atomic_read(&task->tk_count) != 1);
	error = task->tk_status;
	rpc_put_task(task);

out:
	dprintk("svc: %s(), error=%d\n", __func__, error);
	return error;
}
EXPORT_SYMBOL_GPL(bc_svc_process);
#endif /* CONFIG_SUNRPC_BACKCHANNEL */

/*
 * Return (transport-specific) limit on the rpc payload.
 */
u32 svc_max_payload(const struct svc_rqst *rqstp)
{
	u32 max = rqstp->rq_xprt->xpt_class->xcl_max_payload;

	if (rqstp->rq_server->sv_max_payload < max)
		max = rqstp->rq_server->sv_max_payload;
	return max;
}
EXPORT_SYMBOL_GPL(svc_max_payload);

/**
 * svc_fill_write_vector - Construct data argument for VFS write call
 * @rqstp: svc_rqst to operate on
 * @pages: list of pages containing data payload
 * @first: buffer containing first section of write payload
 * @total: total number of bytes of write payload
 *
 * Fills in rqstp::rq_vec, and returns the number of elements.
 */
unsigned int svc_fill_write_vector(struct svc_rqst *rqstp, struct page **pages,
				   struct kvec *first, size_t total)
{
	struct kvec *vec = rqstp->rq_vec;
	unsigned int i;

	/* Some types of transport can present the write payload
	 * entirely in rq_arg.pages. In this case, @first is empty.
	 */
	i = 0;
	if (first->iov_len) {
		vec[i].iov_base = first->iov_base;
		vec[i].iov_len = min_t(size_t, total, first->iov_len);
		total -= vec[i].iov_len;
		++i;
	}

	while (total) {
		vec[i].iov_base = page_address(*pages);
		vec[i].iov_len = min_t(size_t, total, PAGE_SIZE);
		total -= vec[i].iov_len;
		++i;
		++pages;
	}

	WARN_ON_ONCE(i > ARRAY_SIZE(rqstp->rq_vec));
	return i;
}
EXPORT_SYMBOL_GPL(svc_fill_write_vector);

/**
 * svc_fill_symlink_pathname - Construct pathname argument for VFS symlink call
 * @rqstp: svc_rqst to operate on
 * @first: buffer containing first section of pathname
 * @p: buffer containing remaining section of pathname
 * @total: total length of the pathname argument
 *
 * The VFS symlink API demands a NUL-terminated pathname in mapped memory.
 * Returns pointer to a NUL-terminated string, or an ERR_PTR. Caller must free
 * the returned string.
 */
char *svc_fill_symlink_pathname(struct svc_rqst *rqstp, struct kvec *first,
				void *p, size_t total)
{
	size_t len, remaining;
	char *result, *dst;

	result = kmalloc(total + 1, GFP_KERNEL);
	if (!result)
		return ERR_PTR(-ESERVERFAULT);

	dst = result;
	remaining = total;

	len = min_t(size_t, total, first->iov_len);
	if (len) {
		memcpy(dst, first->iov_base, len);
		dst += len;
		remaining -= len;
	}

	if (remaining) {
		len = min_t(size_t, remaining, PAGE_SIZE);
		memcpy(dst, p, len);
		dst += len;
	}

	*dst = '\0';

	/* Sanity check: Linux doesn't allow the pathname argument to
	 * contain a NUL byte.
	 */
	if (strlen(result) != total) {
		kfree(result);
		return ERR_PTR(-EINVAL);
	}
	return result;
}
EXPORT_SYMBOL_GPL(svc_fill_symlink_pathname);