summaryrefslogtreecommitdiffstats
path: root/drivers/infiniband/ulp/iser/iser_verbs.c
blob: ae70cc1463ac2b75d7eae512bf3224e90ba2d59f (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
/*
 * Copyright (c) 2004, 2005, 2006 Voltaire, Inc. All rights reserved.
 * Copyright (c) 2005, 2006 Cisco Systems.  All rights reserved.
 * Copyright (c) 2013-2014 Mellanox Technologies. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *	- Redistributions of source code must retain the above
 *	  copyright notice, this list of conditions and the following
 *	  disclaimer.
 *
 *	- Redistributions in binary form must reproduce the above
 *	  copyright notice, this list of conditions and the following
 *	  disclaimer in the documentation and/or other materials
 *	  provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/delay.h>

#include "iscsi_iser.h"

#define ISCSI_ISER_MAX_CONN	8
#define ISER_MAX_RX_LEN		(ISER_QP_MAX_RECV_DTOS * ISCSI_ISER_MAX_CONN)
#define ISER_MAX_TX_LEN		(ISER_QP_MAX_REQ_DTOS  * ISCSI_ISER_MAX_CONN)
#define ISER_MAX_CQ_LEN		(ISER_MAX_RX_LEN + ISER_MAX_TX_LEN + \
				 ISCSI_ISER_MAX_CONN)

static int iser_cq_poll_limit = 512;

static void iser_cq_tasklet_fn(unsigned long data);
static void iser_cq_callback(struct ib_cq *cq, void *cq_context);

static void iser_cq_event_callback(struct ib_event *cause, void *context)
{
	iser_err("cq event %s (%d)\n",
		 ib_event_msg(cause->event), cause->event);
}

static void iser_qp_event_callback(struct ib_event *cause, void *context)
{
	iser_err("qp event %s (%d)\n",
		 ib_event_msg(cause->event), cause->event);
}

static void iser_event_handler(struct ib_event_handler *handler,
				struct ib_event *event)
{
	iser_err("async event %s (%d) on device %s port %d\n",
		 ib_event_msg(event->event), event->event,
		 event->device->name, event->element.port_num);
}

/**
 * iser_create_device_ib_res - creates Protection Domain (PD), Completion
 * Queue (CQ), DMA Memory Region (DMA MR) with the device associated with
 * the adapator.
 *
 * returns 0 on success, -1 on failure
 */
static int iser_create_device_ib_res(struct iser_device *device)
{
	struct ib_device_attr *dev_attr = &device->dev_attr;
	int ret, i, max_cqe;

	ret = ib_query_device(device->ib_device, dev_attr);
	if (ret) {
		pr_warn("Query device failed for %s\n", device->ib_device->name);
		return ret;
	}

	ret = iser_assign_reg_ops(device);
	if (ret)
		return ret;

	device->comps_used = min_t(int, num_online_cpus(),
				 device->ib_device->num_comp_vectors);

	device->comps = kcalloc(device->comps_used, sizeof(*device->comps),
				GFP_KERNEL);
	if (!device->comps)
		goto comps_err;

	max_cqe = min(ISER_MAX_CQ_LEN, dev_attr->max_cqe);

	iser_info("using %d CQs, device %s supports %d vectors max_cqe %d\n",
		  device->comps_used, device->ib_device->name,
		  device->ib_device->num_comp_vectors, max_cqe);

	device->pd = ib_alloc_pd(device->ib_device);
	if (IS_ERR(device->pd))
		goto pd_err;

	for (i = 0; i < device->comps_used; i++) {
		struct ib_cq_init_attr cq_attr = {};
		struct iser_comp *comp = &device->comps[i];

		comp->device = device;
		cq_attr.cqe = max_cqe;
		cq_attr.comp_vector = i;
		comp->cq = ib_create_cq(device->ib_device,
					iser_cq_callback,
					iser_cq_event_callback,
					(void *)comp,
					&cq_attr);
		if (IS_ERR(comp->cq)) {
			comp->cq = NULL;
			goto cq_err;
		}

		if (ib_req_notify_cq(comp->cq, IB_CQ_NEXT_COMP))
			goto cq_err;

		tasklet_init(&comp->tasklet, iser_cq_tasklet_fn,
			     (unsigned long)comp);
	}

	device->mr = ib_get_dma_mr(device->pd, IB_ACCESS_LOCAL_WRITE |
				   IB_ACCESS_REMOTE_WRITE |
				   IB_ACCESS_REMOTE_READ);
	if (IS_ERR(device->mr))
		goto dma_mr_err;

	INIT_IB_EVENT_HANDLER(&device->event_handler, device->ib_device,
				iser_event_handler);
	if (ib_register_event_handler(&device->event_handler))
		goto handler_err;

	return 0;

handler_err:
	ib_dereg_mr(device->mr);
dma_mr_err:
	for (i = 0; i < device->comps_used; i++)
		tasklet_kill(&device->comps[i].tasklet);
cq_err:
	for (i = 0; i < device->comps_used; i++) {
		struct iser_comp *comp = &device->comps[i];

		if (comp->cq)
			ib_destroy_cq(comp->cq);
	}
	ib_dealloc_pd(device->pd);
pd_err:
	kfree(device->comps);
comps_err:
	iser_err("failed to allocate an IB resource\n");
	return -1;
}

/**
 * iser_free_device_ib_res - destroy/dealloc/dereg the DMA MR,
 * CQ and PD created with the device associated with the adapator.
 */
static void iser_free_device_ib_res(struct iser_device *device)
{
	int i;
	BUG_ON(device->mr == NULL);

	for (i = 0; i < device->comps_used; i++) {
		struct iser_comp *comp = &device->comps[i];

		tasklet_kill(&comp->tasklet);
		ib_destroy_cq(comp->cq);
		comp->cq = NULL;
	}

	(void)ib_unregister_event_handler(&device->event_handler);
	(void)ib_dereg_mr(device->mr);
	ib_dealloc_pd(device->pd);

	kfree(device->comps);
	device->comps = NULL;

	device->mr = NULL;
	device->pd = NULL;
}

/**
 * iser_alloc_fmr_pool - Creates FMR pool and page_vector
 *
 * returns 0 on success, or errno code on failure
 */
int iser_alloc_fmr_pool(struct ib_conn *ib_conn,
			unsigned cmds_max,
			unsigned int size)
{
	struct iser_device *device = ib_conn->device;
	struct iser_fr_pool *fr_pool = &ib_conn->fr_pool;
	struct iser_page_vec *page_vec;
	struct iser_fr_desc *desc;
	struct ib_fmr_pool *fmr_pool;
	struct ib_fmr_pool_param params;
	int ret;

	INIT_LIST_HEAD(&fr_pool->list);
	spin_lock_init(&fr_pool->lock);

	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
	if (!desc)
		return -ENOMEM;

	page_vec = kmalloc(sizeof(*page_vec) + (sizeof(u64) * size),
			   GFP_KERNEL);
	if (!page_vec) {
		ret = -ENOMEM;
		goto err_frpl;
	}

	page_vec->pages = (u64 *)(page_vec + 1);

	params.page_shift        = SHIFT_4K;
	params.max_pages_per_fmr = size;
	/* make the pool size twice the max number of SCSI commands *
	 * the ML is expected to queue, watermark for unmap at 50%  */
	params.pool_size	 = cmds_max * 2;
	params.dirty_watermark	 = cmds_max;
	params.cache		 = 0;
	params.flush_function	 = NULL;
	params.access		 = (IB_ACCESS_LOCAL_WRITE  |
				    IB_ACCESS_REMOTE_WRITE |
				    IB_ACCESS_REMOTE_READ);

	fmr_pool = ib_create_fmr_pool(device->pd, &params);
	if (IS_ERR(fmr_pool)) {
		ret = PTR_ERR(fmr_pool);
		iser_err("FMR allocation failed, err %d\n", ret);
		goto err_fmr;
	}

	desc->rsc.page_vec = page_vec;
	desc->rsc.fmr_pool = fmr_pool;
	list_add(&desc->list, &fr_pool->list);

	return 0;

err_fmr:
	kfree(page_vec);
err_frpl:
	kfree(desc);

	return ret;
}

/**
 * iser_free_fmr_pool - releases the FMR pool and page vec
 */
void iser_free_fmr_pool(struct ib_conn *ib_conn)
{
	struct iser_fr_pool *fr_pool = &ib_conn->fr_pool;
	struct iser_fr_desc *desc;

	desc = list_first_entry(&fr_pool->list,
				struct iser_fr_desc, list);
	list_del(&desc->list);

	iser_info("freeing conn %p fmr pool %p\n",
		  ib_conn, desc->rsc.fmr_pool);

	ib_destroy_fmr_pool(desc->rsc.fmr_pool);
	kfree(desc->rsc.page_vec);
	kfree(desc);
}

static int
iser_alloc_reg_res(struct ib_device *ib_device,
		   struct ib_pd *pd,
		   struct iser_reg_resources *res,
		   unsigned int size)
{
	int ret;

	res->frpl = ib_alloc_fast_reg_page_list(ib_device, size);
	if (IS_ERR(res->frpl)) {
		ret = PTR_ERR(res->frpl);
		iser_err("Failed to allocate ib_fast_reg_page_list err=%d\n",
			 ret);
		return PTR_ERR(res->frpl);
	}

	res->mr = ib_alloc_mr(pd, IB_MR_TYPE_MEM_REG, size);
	if (IS_ERR(res->mr)) {
		ret = PTR_ERR(res->mr);
		iser_err("Failed to allocate ib_fast_reg_mr err=%d\n", ret);
		goto fast_reg_mr_failure;
	}
	res->mr_valid = 1;

	return 0;

fast_reg_mr_failure:
	ib_free_fast_reg_page_list(res->frpl);

	return ret;
}

static void
iser_free_reg_res(struct iser_reg_resources *rsc)
{
	ib_dereg_mr(rsc->mr);
	ib_free_fast_reg_page_list(rsc->frpl);
}

static int
iser_alloc_pi_ctx(struct ib_device *ib_device,
		  struct ib_pd *pd,
		  struct iser_fr_desc *desc,
		  unsigned int size)
{
	struct iser_pi_context *pi_ctx = NULL;
	int ret;

	desc->pi_ctx = kzalloc(sizeof(*desc->pi_ctx), GFP_KERNEL);
	if (!desc->pi_ctx)
		return -ENOMEM;

	pi_ctx = desc->pi_ctx;

	ret = iser_alloc_reg_res(ib_device, pd, &pi_ctx->rsc, size);
	if (ret) {
		iser_err("failed to allocate reg_resources\n");
		goto alloc_reg_res_err;
	}

	pi_ctx->sig_mr = ib_alloc_mr(pd, IB_MR_TYPE_SIGNATURE, 2);
	if (IS_ERR(pi_ctx->sig_mr)) {
		ret = PTR_ERR(pi_ctx->sig_mr);
		goto sig_mr_failure;
	}
	pi_ctx->sig_mr_valid = 1;
	desc->pi_ctx->sig_protected = 0;

	return 0;

sig_mr_failure:
	iser_free_reg_res(&pi_ctx->rsc);
alloc_reg_res_err:
	kfree(desc->pi_ctx);

	return ret;
}

static void
iser_free_pi_ctx(struct iser_pi_context *pi_ctx)
{
	iser_free_reg_res(&pi_ctx->rsc);
	ib_dereg_mr(pi_ctx->sig_mr);
	kfree(pi_ctx);
}

static struct iser_fr_desc *
iser_create_fastreg_desc(struct ib_device *ib_device,
			 struct ib_pd *pd,
			 bool pi_enable,
			 unsigned int size)
{
	struct iser_fr_desc *desc;
	int ret;

	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
	if (!desc)
		return ERR_PTR(-ENOMEM);

	ret = iser_alloc_reg_res(ib_device, pd, &desc->rsc, size);
	if (ret)
		goto reg_res_alloc_failure;

	if (pi_enable) {
		ret = iser_alloc_pi_ctx(ib_device, pd, desc, size);
		if (ret)
			goto pi_ctx_alloc_failure;
	}

	return desc;

pi_ctx_alloc_failure:
	iser_free_reg_res(&desc->rsc);
reg_res_alloc_failure:
	kfree(desc);

	return ERR_PTR(ret);
}

/**
 * iser_alloc_fastreg_pool - Creates pool of fast_reg descriptors
 * for fast registration work requests.
 * returns 0 on success, or errno code on failure
 */
int iser_alloc_fastreg_pool(struct ib_conn *ib_conn,
			    unsigned cmds_max,
			    unsigned int size)
{
	struct iser_device *device = ib_conn->device;
	struct iser_fr_pool *fr_pool = &ib_conn->fr_pool;
	struct iser_fr_desc *desc;
	int i, ret;

	INIT_LIST_HEAD(&fr_pool->list);
	spin_lock_init(&fr_pool->lock);
	fr_pool->size = 0;
	for (i = 0; i < cmds_max; i++) {
		desc = iser_create_fastreg_desc(device->ib_device, device->pd,
						ib_conn->pi_support, size);
		if (IS_ERR(desc)) {
			ret = PTR_ERR(desc);
			goto err;
		}

		list_add_tail(&desc->list, &fr_pool->list);
		fr_pool->size++;
	}

	return 0;

err:
	iser_free_fastreg_pool(ib_conn);
	return ret;
}

/**
 * iser_free_fastreg_pool - releases the pool of fast_reg descriptors
 */
void iser_free_fastreg_pool(struct ib_conn *ib_conn)
{
	struct iser_fr_pool *fr_pool = &ib_conn->fr_pool;
	struct iser_fr_desc *desc, *tmp;
	int i = 0;

	if (list_empty(&fr_pool->list))
		return;

	iser_info("freeing conn %p fr pool\n", ib_conn);

	list_for_each_entry_safe(desc, tmp, &fr_pool->list, list) {
		list_del(&desc->list);
		iser_free_reg_res(&desc->rsc);
		if (desc->pi_ctx)
			iser_free_pi_ctx(desc->pi_ctx);
		kfree(desc);
		++i;
	}

	if (i < fr_pool->size)
		iser_warn("pool still has %d regions registered\n",
			  fr_pool->size - i);
}

/**
 * iser_create_ib_conn_res - Queue-Pair (QP)
 *
 * returns 0 on success, -1 on failure
 */
static int iser_create_ib_conn_res(struct ib_conn *ib_conn)
{
	struct iser_conn *iser_conn = container_of(ib_conn, struct iser_conn,
						   ib_conn);
	struct iser_device	*device;
	struct ib_device_attr *dev_attr;
	struct ib_qp_init_attr	init_attr;
	int			ret = -ENOMEM;
	int index, min_index = 0;

	BUG_ON(ib_conn->device == NULL);

	device = ib_conn->device;
	dev_attr = &device->dev_attr;

	memset(&init_attr, 0, sizeof init_attr);

	mutex_lock(&ig.connlist_mutex);
	/* select the CQ with the minimal number of usages */
	for (index = 0; index < device->comps_used; index++) {
		if (device->comps[index].active_qps <
		    device->comps[min_index].active_qps)
			min_index = index;
	}
	ib_conn->comp = &device->comps[min_index];
	ib_conn->comp->active_qps++;
	mutex_unlock(&ig.connlist_mutex);
	iser_info("cq index %d used for ib_conn %p\n", min_index, ib_conn);

	init_attr.event_handler = iser_qp_event_callback;
	init_attr.qp_context	= (void *)ib_conn;
	init_attr.send_cq	= ib_conn->comp->cq;
	init_attr.recv_cq	= ib_conn->comp->cq;
	init_attr.cap.max_recv_wr  = ISER_QP_MAX_RECV_DTOS;
	init_attr.cap.max_send_sge = 2;
	init_attr.cap.max_recv_sge = 1;
	init_attr.sq_sig_type	= IB_SIGNAL_REQ_WR;
	init_attr.qp_type	= IB_QPT_RC;
	if (ib_conn->pi_support) {
		init_attr.cap.max_send_wr = ISER_QP_SIG_MAX_REQ_DTOS + 1;
		init_attr.create_flags |= IB_QP_CREATE_SIGNATURE_EN;
		iser_conn->max_cmds =
			ISER_GET_MAX_XMIT_CMDS(ISER_QP_SIG_MAX_REQ_DTOS);
	} else {
		if (dev_attr->max_qp_wr > ISER_QP_MAX_REQ_DTOS) {
			init_attr.cap.max_send_wr  = ISER_QP_MAX_REQ_DTOS + 1;
			iser_conn->max_cmds =
				ISER_GET_MAX_XMIT_CMDS(ISER_QP_MAX_REQ_DTOS);
		} else {
			init_attr.cap.max_send_wr = dev_attr->max_qp_wr;
			iser_conn->max_cmds =
				ISER_GET_MAX_XMIT_CMDS(dev_attr->max_qp_wr);
			iser_dbg("device %s supports max_send_wr %d\n",
				 device->ib_device->name, dev_attr->max_qp_wr);
		}
	}

	ret = rdma_create_qp(ib_conn->cma_id, device->pd, &init_attr);
	if (ret)
		goto out_err;

	ib_conn->qp = ib_conn->cma_id->qp;
	iser_info("setting conn %p cma_id %p qp %p\n",
		  ib_conn, ib_conn->cma_id,
		  ib_conn->cma_id->qp);
	return ret;

out_err:
	mutex_lock(&ig.connlist_mutex);
	ib_conn->comp->active_qps--;
	mutex_unlock(&ig.connlist_mutex);
	iser_err("unable to alloc mem or create resource, err %d\n", ret);

	return ret;
}

/**
 * based on the resolved device node GUID see if there already allocated
 * device for this device. If there's no such, create one.
 */
static
struct iser_device *iser_device_find_by_ib_device(struct rdma_cm_id *cma_id)
{
	struct iser_device *device;

	mutex_lock(&ig.device_list_mutex);

	list_for_each_entry(device, &ig.device_list, ig_list)
		/* find if there's a match using the node GUID */
		if (device->ib_device->node_guid == cma_id->device->node_guid)
			goto inc_refcnt;

	device = kzalloc(sizeof *device, GFP_KERNEL);
	if (device == NULL)
		goto out;

	/* assign this device to the device */
	device->ib_device = cma_id->device;
	/* init the device and link it into ig device list */
	if (iser_create_device_ib_res(device)) {
		kfree(device);
		device = NULL;
		goto out;
	}
	list_add(&device->ig_list, &ig.device_list);

inc_refcnt:
	device->refcount++;
out:
	mutex_unlock(&ig.device_list_mutex);
	return device;
}

/* if there's no demand for this device, release it */
static void iser_device_try_release(struct iser_device *device)
{
	mutex_lock(&ig.device_list_mutex);
	device->refcount--;
	iser_info("device %p refcount %d\n", device, device->refcount);
	if (!device->refcount) {
		iser_free_device_ib_res(device);
		list_del(&device->ig_list);
		kfree(device);
	}
	mutex_unlock(&ig.device_list_mutex);
}

/**
 * Called with state mutex held
 **/
static int iser_conn_state_comp_exch(struct iser_conn *iser_conn,
				     enum iser_conn_state comp,
				     enum iser_conn_state exch)
{
	int ret;

	ret = (iser_conn->state == comp);
	if (ret)
		iser_conn->state = exch;

	return ret;
}

void iser_release_work(struct work_struct *work)
{
	struct iser_conn *iser_conn;

	iser_conn = container_of(work, struct iser_conn, release_work);

	/* Wait for conn_stop to complete */
	wait_for_completion(&iser_conn->stop_completion);
	/* Wait for IB resouces cleanup to complete */
	wait_for_completion(&iser_conn->ib_completion);

	mutex_lock(&iser_conn->state_mutex);
	iser_conn->state = ISER_CONN_DOWN;
	mutex_unlock(&iser_conn->state_mutex);

	iser_conn_release(iser_conn);
}

/**
 * iser_free_ib_conn_res - release IB related resources
 * @iser_conn: iser connection struct
 * @destroy: indicator if we need to try to release the
 *     iser device and memory regoins pool (only iscsi
 *     shutdown and DEVICE_REMOVAL will use this).
 *
 * This routine is called with the iser state mutex held
 * so the cm_id removal is out of here. It is Safe to
 * be invoked multiple times.
 */
static void iser_free_ib_conn_res(struct iser_conn *iser_conn,
				  bool destroy)
{
	struct ib_conn *ib_conn = &iser_conn->ib_conn;
	struct iser_device *device = ib_conn->device;

	iser_info("freeing conn %p cma_id %p qp %p\n",
		  iser_conn, ib_conn->cma_id, ib_conn->qp);

	if (ib_conn->qp != NULL) {
		ib_conn->comp->active_qps--;
		rdma_destroy_qp(ib_conn->cma_id);
		ib_conn->qp = NULL;
	}

	if (destroy) {
		if (iser_conn->rx_descs)
			iser_free_rx_descriptors(iser_conn);

		if (device != NULL) {
			iser_device_try_release(device);
			ib_conn->device = NULL;
		}
	}
}

/**
 * Frees all conn objects and deallocs conn descriptor
 */
void iser_conn_release(struct iser_conn *iser_conn)
{
	struct ib_conn *ib_conn = &iser_conn->ib_conn;

	mutex_lock(&ig.connlist_mutex);
	list_del(&iser_conn->conn_list);
	mutex_unlock(&ig.connlist_mutex);

	mutex_lock(&iser_conn->state_mutex);
	/* In case we endup here without ep_disconnect being invoked. */
	if (iser_conn->state != ISER_CONN_DOWN) {
		iser_warn("iser conn %p state %d, expected state down.\n",
			  iser_conn, iser_conn->state);
		iscsi_destroy_endpoint(iser_conn->ep);
		iser_conn->state = ISER_CONN_DOWN;
	}
	/*
	 * In case we never got to bind stage, we still need to
	 * release IB resources (which is safe to call more than once).
	 */
	iser_free_ib_conn_res(iser_conn, true);
	mutex_unlock(&iser_conn->state_mutex);

	if (ib_conn->cma_id != NULL) {
		rdma_destroy_id(ib_conn->cma_id);
		ib_conn->cma_id = NULL;
	}

	kfree(iser_conn);
}

/**
 * triggers start of the disconnect procedures and wait for them to be done
 * Called with state mutex held
 */
int iser_conn_terminate(struct iser_conn *iser_conn)
{
	struct ib_conn *ib_conn = &iser_conn->ib_conn;
	struct ib_send_wr *bad_wr;
	int err = 0;

	/* terminate the iser conn only if the conn state is UP */
	if (!iser_conn_state_comp_exch(iser_conn, ISER_CONN_UP,
				       ISER_CONN_TERMINATING))
		return 0;

	iser_info("iser_conn %p state %d\n", iser_conn, iser_conn->state);

	/* suspend queuing of new iscsi commands */
	if (iser_conn->iscsi_conn)
		iscsi_suspend_queue(iser_conn->iscsi_conn);

	/*
	 * In case we didn't already clean up the cma_id (peer initiated
	 * a disconnection), we need to Cause the CMA to change the QP
	 * state to ERROR.
	 */
	if (ib_conn->cma_id) {
		err = rdma_disconnect(ib_conn->cma_id);
		if (err)
			iser_err("Failed to disconnect, conn: 0x%p err %d\n",
				 iser_conn, err);

		/* post an indication that all flush errors were consumed */
		err = ib_post_send(ib_conn->qp, &ib_conn->beacon, &bad_wr);
		if (err) {
			iser_err("conn %p failed to post beacon", ib_conn);
			return 1;
		}

		wait_for_completion(&ib_conn->flush_comp);
	}

	return 1;
}

/**
 * Called with state mutex held
 **/
static void iser_connect_error(struct rdma_cm_id *cma_id)
{
	struct iser_conn *iser_conn;

	iser_conn = (struct iser_conn *)cma_id->context;
	iser_conn->state = ISER_CONN_TERMINATING;
}

static void
iser_calc_scsi_params(struct iser_conn *iser_conn,
		      unsigned int max_sectors)
{
	struct iser_device *device = iser_conn->ib_conn.device;
	unsigned short sg_tablesize, sup_sg_tablesize;

	sg_tablesize = DIV_ROUND_UP(max_sectors * 512, SIZE_4K);
	sup_sg_tablesize = min_t(unsigned, ISCSI_ISER_MAX_SG_TABLESIZE,
				 device->dev_attr.max_fast_reg_page_list_len);

	if (sg_tablesize > sup_sg_tablesize) {
		sg_tablesize = sup_sg_tablesize;
		iser_conn->scsi_max_sectors = sg_tablesize * SIZE_4K / 512;
	} else {
		iser_conn->scsi_max_sectors = max_sectors;
	}

	iser_conn->scsi_sg_tablesize = sg_tablesize;

	iser_dbg("iser_conn %p, sg_tablesize %u, max_sectors %u\n",
		 iser_conn, iser_conn->scsi_sg_tablesize,
		 iser_conn->scsi_max_sectors);
}

/**
 * Called with state mutex held
 **/
static void iser_addr_handler(struct rdma_cm_id *cma_id)
{
	struct iser_device *device;
	struct iser_conn   *iser_conn;
	struct ib_conn   *ib_conn;
	int    ret;

	iser_conn = (struct iser_conn *)cma_id->context;
	if (iser_conn->state != ISER_CONN_PENDING)
		/* bailout */
		return;

	ib_conn = &iser_conn->ib_conn;
	device = iser_device_find_by_ib_device(cma_id);
	if (!device) {
		iser_err("device lookup/creation failed\n");
		iser_connect_error(cma_id);
		return;
	}

	ib_conn->device = device;

	/* connection T10-PI support */
	if (iser_pi_enable) {
		if (!(device->dev_attr.device_cap_flags &
		      IB_DEVICE_SIGNATURE_HANDOVER)) {
			iser_warn("T10-PI requested but not supported on %s, "
				  "continue without T10-PI\n",
				  ib_conn->device->ib_device->name);
			ib_conn->pi_support = false;
		} else {
			ib_conn->pi_support = true;
		}
	}

	iser_calc_scsi_params(iser_conn, iser_max_sectors);

	ret = rdma_resolve_route(cma_id, 1000);
	if (ret) {
		iser_err("resolve route failed: %d\n", ret);
		iser_connect_error(cma_id);
		return;
	}
}

/**
 * Called with state mutex held
 **/
static void iser_route_handler(struct rdma_cm_id *cma_id)
{
	struct rdma_conn_param conn_param;
	int    ret;
	struct iser_cm_hdr req_hdr;
	struct iser_conn *iser_conn = (struct iser_conn *)cma_id->context;
	struct ib_conn *ib_conn = &iser_conn->ib_conn;
	struct iser_device *device = ib_conn->device;

	if (iser_conn->state != ISER_CONN_PENDING)
		/* bailout */
		return;

	ret = iser_create_ib_conn_res(ib_conn);
	if (ret)
		goto failure;

	memset(&conn_param, 0, sizeof conn_param);
	conn_param.responder_resources = device->dev_attr.max_qp_rd_atom;
	conn_param.initiator_depth     = 1;
	conn_param.retry_count	       = 7;
	conn_param.rnr_retry_count     = 6;

	memset(&req_hdr, 0, sizeof(req_hdr));
	req_hdr.flags = (ISER_ZBVA_NOT_SUPPORTED |
			ISER_SEND_W_INV_NOT_SUPPORTED);
	conn_param.private_data		= (void *)&req_hdr;
	conn_param.private_data_len	= sizeof(struct iser_cm_hdr);

	ret = rdma_connect(cma_id, &conn_param);
	if (ret) {
		iser_err("failure connecting: %d\n", ret);
		goto failure;
	}

	return;
failure:
	iser_connect_error(cma_id);
}

static void iser_connected_handler(struct rdma_cm_id *cma_id)
{
	struct iser_conn *iser_conn;
	struct ib_qp_attr attr;
	struct ib_qp_init_attr init_attr;

	iser_conn = (struct iser_conn *)cma_id->context;
	if (iser_conn->state != ISER_CONN_PENDING)
		/* bailout */
		return;

	(void)ib_query_qp(cma_id->qp, &attr, ~0, &init_attr);
	iser_info("remote qpn:%x my qpn:%x\n", attr.dest_qp_num, cma_id->qp->qp_num);

	iser_conn->state = ISER_CONN_UP;
	complete(&iser_conn->up_completion);
}

static void iser_disconnected_handler(struct rdma_cm_id *cma_id)
{
	struct iser_conn *iser_conn = (struct iser_conn *)cma_id->context;

	if (iser_conn_terminate(iser_conn)) {
		if (iser_conn->iscsi_conn)
			iscsi_conn_failure(iser_conn->iscsi_conn,
					   ISCSI_ERR_CONN_FAILED);
		else
			iser_err("iscsi_iser connection isn't bound\n");
	}
}

static void iser_cleanup_handler(struct rdma_cm_id *cma_id,
				 bool destroy)
{
	struct iser_conn *iser_conn = (struct iser_conn *)cma_id->context;

	/*
	 * We are not guaranteed that we visited disconnected_handler
	 * by now, call it here to be safe that we handle CM drep
	 * and flush errors.
	 */
	iser_disconnected_handler(cma_id);
	iser_free_ib_conn_res(iser_conn, destroy);
	complete(&iser_conn->ib_completion);
};

static int iser_cma_handler(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
{
	struct iser_conn *iser_conn;
	int ret = 0;

	iser_conn = (struct iser_conn *)cma_id->context;
	iser_info("%s (%d): status %d conn %p id %p\n",
		  rdma_event_msg(event->event), event->event,
		  event->status, cma_id->context, cma_id);

	mutex_lock(&iser_conn->state_mutex);
	switch (event->event) {
	case RDMA_CM_EVENT_ADDR_RESOLVED:
		iser_addr_handler(cma_id);
		break;
	case RDMA_CM_EVENT_ROUTE_RESOLVED:
		iser_route_handler(cma_id);
		break;
	case RDMA_CM_EVENT_ESTABLISHED:
		iser_connected_handler(cma_id);
		break;
	case RDMA_CM_EVENT_ADDR_ERROR:
	case RDMA_CM_EVENT_ROUTE_ERROR:
	case RDMA_CM_EVENT_CONNECT_ERROR:
	case RDMA_CM_EVENT_UNREACHABLE:
	case RDMA_CM_EVENT_REJECTED:
		iser_connect_error(cma_id);
		break;
	case RDMA_CM_EVENT_DISCONNECTED:
	case RDMA_CM_EVENT_ADDR_CHANGE:
	case RDMA_CM_EVENT_TIMEWAIT_EXIT:
		iser_cleanup_handler(cma_id, false);
		break;
	case RDMA_CM_EVENT_DEVICE_REMOVAL:
		/*
		 * we *must* destroy the device as we cannot rely
		 * on iscsid to be around to initiate error handling.
		 * also if we are not in state DOWN implicitly destroy
		 * the cma_id.
		 */
		iser_cleanup_handler(cma_id, true);
		if (iser_conn->state != ISER_CONN_DOWN) {
			iser_conn->ib_conn.cma_id = NULL;
			ret = 1;
		}
		break;
	default:
		iser_err("Unexpected RDMA CM event: %s (%d)\n",
			 rdma_event_msg(event->event), event->event);
		break;
	}
	mutex_unlock(&iser_conn->state_mutex);

	return ret;
}

void iser_conn_init(struct iser_conn *iser_conn)
{
	iser_conn->state = ISER_CONN_INIT;
	iser_conn->ib_conn.post_recv_buf_count = 0;
	init_completion(&iser_conn->ib_conn.flush_comp);
	init_completion(&iser_conn->stop_completion);
	init_completion(&iser_conn->ib_completion);
	init_completion(&iser_conn->up_completion);
	INIT_LIST_HEAD(&iser_conn->conn_list);
	mutex_init(&iser_conn->state_mutex);
}

 /**
 * starts the process of connecting to the target
 * sleeps until the connection is established or rejected
 */
int iser_connect(struct iser_conn   *iser_conn,
		 struct sockaddr    *src_addr,
		 struct sockaddr    *dst_addr,
		 int                 non_blocking)
{
	struct ib_conn *ib_conn = &iser_conn->ib_conn;
	int err = 0;

	mutex_lock(&iser_conn->state_mutex);

	sprintf(iser_conn->name, "%pISp", dst_addr);

	iser_info("connecting to: %s\n", iser_conn->name);

	/* the device is known only --after-- address resolution */
	ib_conn->device = NULL;

	iser_conn->state = ISER_CONN_PENDING;

	ib_conn->beacon.wr_id = ISER_BEACON_WRID;
	ib_conn->beacon.opcode = IB_WR_SEND;

	ib_conn->cma_id = rdma_create_id(iser_cma_handler,
					 (void *)iser_conn,
					 RDMA_PS_TCP, IB_QPT_RC);
	if (IS_ERR(ib_conn->cma_id)) {
		err = PTR_ERR(ib_conn->cma_id);
		iser_err("rdma_create_id failed: %d\n", err);
		goto id_failure;
	}

	err = rdma_resolve_addr(ib_conn->cma_id, src_addr, dst_addr, 1000);
	if (err) {
		iser_err("rdma_resolve_addr failed: %d\n", err);
		goto addr_failure;
	}

	if (!non_blocking) {
		wait_for_completion_interruptible(&iser_conn->up_completion);

		if (iser_conn->state != ISER_CONN_UP) {
			err =  -EIO;
			goto connect_failure;
		}
	}
	mutex_unlock(&iser_conn->state_mutex);

	mutex_lock(&ig.connlist_mutex);
	list_add(&iser_conn->conn_list, &ig.connlist);
	mutex_unlock(&ig.connlist_mutex);
	return 0;

id_failure:
	ib_conn->cma_id = NULL;
addr_failure:
	iser_conn->state = ISER_CONN_DOWN;
connect_failure:
	mutex_unlock(&iser_conn->state_mutex);
	iser_conn_release(iser_conn);
	return err;
}

int iser_post_recvl(struct iser_conn *iser_conn)
{
	struct ib_recv_wr rx_wr, *rx_wr_failed;
	struct ib_conn *ib_conn = &iser_conn->ib_conn;
	struct ib_sge	  sge;
	int ib_ret;

	sge.addr   = iser_conn->login_resp_dma;
	sge.length = ISER_RX_LOGIN_SIZE;
	sge.lkey   = ib_conn->device->pd->local_dma_lkey;

	rx_wr.wr_id   = (uintptr_t)iser_conn->login_resp_buf;
	rx_wr.sg_list = &sge;
	rx_wr.num_sge = 1;
	rx_wr.next    = NULL;

	ib_conn->post_recv_buf_count++;
	ib_ret	= ib_post_recv(ib_conn->qp, &rx_wr, &rx_wr_failed);
	if (ib_ret) {
		iser_err("ib_post_recv failed ret=%d\n", ib_ret);
		ib_conn->post_recv_buf_count--;
	}
	return ib_ret;
}

int iser_post_recvm(struct iser_conn *iser_conn, int count)
{
	struct ib_recv_wr *rx_wr, *rx_wr_failed;
	int i, ib_ret;
	struct ib_conn *ib_conn = &iser_conn->ib_conn;
	unsigned int my_rx_head = iser_conn->rx_desc_head;
	struct iser_rx_desc *rx_desc;

	for (rx_wr = ib_conn->rx_wr, i = 0; i < count; i++, rx_wr++) {
		rx_desc		= &iser_conn->rx_descs[my_rx_head];
		rx_wr->wr_id	= (uintptr_t)rx_desc;
		rx_wr->sg_list	= &rx_desc->rx_sg;
		rx_wr->num_sge	= 1;
		rx_wr->next	= rx_wr + 1;
		my_rx_head = (my_rx_head + 1) & iser_conn->qp_max_recv_dtos_mask;
	}

	rx_wr--;
	rx_wr->next = NULL; /* mark end of work requests list */

	ib_conn->post_recv_buf_count += count;
	ib_ret	= ib_post_recv(ib_conn->qp, ib_conn->rx_wr, &rx_wr_failed);
	if (ib_ret) {
		iser_err("ib_post_recv failed ret=%d\n", ib_ret);
		ib_conn->post_recv_buf_count -= count;
	} else
		iser_conn->rx_desc_head = my_rx_head;
	return ib_ret;
}


/**
 * iser_start_send - Initiate a Send DTO operation
 *
 * returns 0 on success, -1 on failure
 */
int iser_post_send(struct ib_conn *ib_conn, struct iser_tx_desc *tx_desc,
		   bool signal)
{
	struct ib_send_wr *bad_wr, *wr = iser_tx_next_wr(tx_desc);
	int ib_ret;

	ib_dma_sync_single_for_device(ib_conn->device->ib_device,
				      tx_desc->dma_addr, ISER_HEADERS_LEN,
				      DMA_TO_DEVICE);

	wr->next = NULL;
	wr->wr_id = (uintptr_t)tx_desc;
	wr->sg_list = tx_desc->tx_sg;
	wr->num_sge = tx_desc->num_sge;
	wr->opcode = IB_WR_SEND;
	wr->send_flags = signal ? IB_SEND_SIGNALED : 0;

	ib_ret = ib_post_send(ib_conn->qp, &tx_desc->wrs[0], &bad_wr);
	if (ib_ret)
		iser_err("ib_post_send failed, ret:%d opcode:%d\n",
			 ib_ret, bad_wr->opcode);

	return ib_ret;
}

/**
 * is_iser_tx_desc - Indicate if the completion wr_id
 *     is a TX descriptor or not.
 * @iser_conn: iser connection
 * @wr_id: completion WR identifier
 *
 * Since we cannot rely on wc opcode in FLUSH errors
 * we must work around it by checking if the wr_id address
 * falls in the iser connection rx_descs buffer. If so
 * it is an RX descriptor, otherwize it is a TX.
 */
static inline bool
is_iser_tx_desc(struct iser_conn *iser_conn, void *wr_id)
{
	void *start = iser_conn->rx_descs;
	int len = iser_conn->num_rx_descs * sizeof(*iser_conn->rx_descs);

	if (wr_id >= start && wr_id < start + len)
		return false;

	return true;
}

/**
 * iser_handle_comp_error() - Handle error completion
 * @ib_conn:   connection RDMA resources
 * @wc:        work completion
 *
 * Notes: We may handle a FLUSH error completion and in this case
 *        we only cleanup in case TX type was DATAOUT. For non-FLUSH
 *        error completion we should also notify iscsi layer that
 *        connection is failed (in case we passed bind stage).
 */
static void
iser_handle_comp_error(struct ib_conn *ib_conn,
		       struct ib_wc *wc)
{
	void *wr_id = (void *)(uintptr_t)wc->wr_id;
	struct iser_conn *iser_conn = container_of(ib_conn, struct iser_conn,
						   ib_conn);

	if (wc->status != IB_WC_WR_FLUSH_ERR)
		if (iser_conn->iscsi_conn)
			iscsi_conn_failure(iser_conn->iscsi_conn,
					   ISCSI_ERR_CONN_FAILED);

	if (wc->wr_id == ISER_FASTREG_LI_WRID)
		return;

	if (is_iser_tx_desc(iser_conn, wr_id)) {
		struct iser_tx_desc *desc = wr_id;

		if (desc->type == ISCSI_TX_DATAOUT)
			kmem_cache_free(ig.desc_cache, desc);
	} else {
		ib_conn->post_recv_buf_count--;
	}
}

/**
 * iser_handle_wc - handle a single work completion
 * @wc: work completion
 *
 * Soft-IRQ context, work completion can be either
 * SEND or RECV, and can turn out successful or
 * with error (or flush error).
 */
static void iser_handle_wc(struct ib_wc *wc)
{
	struct ib_conn *ib_conn;
	struct iser_tx_desc *tx_desc;
	struct iser_rx_desc *rx_desc;

	ib_conn = wc->qp->qp_context;
	if (likely(wc->status == IB_WC_SUCCESS)) {
		if (wc->opcode == IB_WC_RECV) {
			rx_desc = (struct iser_rx_desc *)(uintptr_t)wc->wr_id;
			iser_rcv_completion(rx_desc, wc->byte_len,
					    ib_conn);
		} else
		if (wc->opcode == IB_WC_SEND) {
			tx_desc = (struct iser_tx_desc *)(uintptr_t)wc->wr_id;
			iser_snd_completion(tx_desc, ib_conn);
		} else {
			iser_err("Unknown wc opcode %d\n", wc->opcode);
		}
	} else {
		if (wc->status != IB_WC_WR_FLUSH_ERR)
			iser_err("%s (%d): wr id %llx vend_err %x\n",
				 ib_wc_status_msg(wc->status), wc->status,
				 wc->wr_id, wc->vendor_err);
		else
			iser_dbg("%s (%d): wr id %llx\n",
				 ib_wc_status_msg(wc->status), wc->status,
				 wc->wr_id);

		if (wc->wr_id == ISER_BEACON_WRID)
			/* all flush errors were consumed */
			complete(&ib_conn->flush_comp);
		else
			iser_handle_comp_error(ib_conn, wc);
	}
}

/**
 * iser_cq_tasklet_fn - iSER completion polling loop
 * @data: iSER completion context
 *
 * Soft-IRQ context, polling connection CQ until
 * either CQ was empty or we exausted polling budget
 */
static void iser_cq_tasklet_fn(unsigned long data)
{
	struct iser_comp *comp = (struct iser_comp *)data;
	struct ib_cq *cq = comp->cq;
	struct ib_wc *const wcs = comp->wcs;
	int i, n, completed = 0;

	while ((n = ib_poll_cq(cq, ARRAY_SIZE(comp->wcs), wcs)) > 0) {
		for (i = 0; i < n; i++)
			iser_handle_wc(&wcs[i]);

		completed += n;
		if (completed >= iser_cq_poll_limit)
			break;
	}

	/*
	 * It is assumed here that arming CQ only once its empty
	 * would not cause interrupts to be missed.
	 */
	ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);

	iser_dbg("got %d completions\n", completed);
}

static void iser_cq_callback(struct ib_cq *cq, void *cq_context)
{
	struct iser_comp *comp = cq_context;

	tasklet_schedule(&comp->tasklet);
}

u8 iser_check_task_pi_status(struct iscsi_iser_task *iser_task,
			     enum iser_data_dir cmd_dir, sector_t *sector)
{
	struct iser_mem_reg *reg = &iser_task->rdma_reg[cmd_dir];
	struct iser_fr_desc *desc = reg->mem_h;
	unsigned long sector_size = iser_task->sc->device->sector_size;
	struct ib_mr_status mr_status;
	int ret;

	if (desc && desc->pi_ctx->sig_protected) {
		desc->pi_ctx->sig_protected = 0;
		ret = ib_check_mr_status(desc->pi_ctx->sig_mr,
					 IB_MR_CHECK_SIG_STATUS, &mr_status);
		if (ret) {
			pr_err("ib_check_mr_status failed, ret %d\n", ret);
			goto err;
		}

		if (mr_status.fail_status & IB_MR_CHECK_SIG_STATUS) {
			sector_t sector_off = mr_status.sig_err.sig_err_offset;

			do_div(sector_off, sector_size + 8);
			*sector = scsi_get_lba(iser_task->sc) + sector_off;

			pr_err("PI error found type %d at sector %llx "
			       "expected %x vs actual %x\n",
			       mr_status.sig_err.err_type,
			       (unsigned long long)*sector,
			       mr_status.sig_err.expected,
			       mr_status.sig_err.actual);

			switch (mr_status.sig_err.err_type) {
			case IB_SIG_BAD_GUARD:
				return 0x1;
			case IB_SIG_BAD_REFTAG:
				return 0x3;
			case IB_SIG_BAD_APPTAG:
				return 0x2;
			}
		}
	}

	return 0;
err:
	/* Not alot we can do here, return ambiguous guard error */
	return 0x1;
}