summaryrefslogtreecommitdiffstats
path: root/net/sunrpc/xprtrdma/verbs.c
blob: f73d7a71035c2576082ad9d43cd9910752289e38 (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
/*
 * Copyright (c) 2003-2007 Network Appliance, Inc. 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 BSD-type
 * 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.
 *
 *      Neither the name of the Network Appliance, Inc. nor the names of
 *      its contributors may be used to endorse or promote products
 *      derived from this software without specific prior written
 *      permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * verbs.c
 *
 * Encapsulates the major functions managing:
 *  o adapters
 *  o endpoints
 *  o connections
 *  o buffer memory
 */

#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/prefetch.h>
#include <linux/sunrpc/addr.h>
#include <asm/bitops.h>
#include <linux/module.h> /* try_module_get()/module_put() */

#include "xprt_rdma.h"

/*
 * Globals/Macros
 */

#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY	RPCDBG_TRANS
#endif

/*
 * internal functions
 */

/*
 * handle replies in tasklet context, using a single, global list
 * rdma tasklet function -- just turn around and call the func
 * for all replies on the list
 */

static DEFINE_SPINLOCK(rpcrdma_tk_lock_g);
static LIST_HEAD(rpcrdma_tasklets_g);

static void
rpcrdma_run_tasklet(unsigned long data)
{
	struct rpcrdma_rep *rep;
	unsigned long flags;

	data = data;
	spin_lock_irqsave(&rpcrdma_tk_lock_g, flags);
	while (!list_empty(&rpcrdma_tasklets_g)) {
		rep = list_entry(rpcrdma_tasklets_g.next,
				 struct rpcrdma_rep, rr_list);
		list_del(&rep->rr_list);
		spin_unlock_irqrestore(&rpcrdma_tk_lock_g, flags);

		rpcrdma_reply_handler(rep);

		spin_lock_irqsave(&rpcrdma_tk_lock_g, flags);
	}
	spin_unlock_irqrestore(&rpcrdma_tk_lock_g, flags);
}

static DECLARE_TASKLET(rpcrdma_tasklet_g, rpcrdma_run_tasklet, 0UL);

static void
rpcrdma_schedule_tasklet(struct list_head *sched_list)
{
	unsigned long flags;

	spin_lock_irqsave(&rpcrdma_tk_lock_g, flags);
	list_splice_tail(sched_list, &rpcrdma_tasklets_g);
	spin_unlock_irqrestore(&rpcrdma_tk_lock_g, flags);
	tasklet_schedule(&rpcrdma_tasklet_g);
}

static void
rpcrdma_qp_async_error_upcall(struct ib_event *event, void *context)
{
	struct rpcrdma_ep *ep = context;

	pr_err("RPC:       %s: %s on device %s ep %p\n",
	       __func__, ib_event_msg(event->event),
		event->device->name, context);
	if (ep->rep_connected == 1) {
		ep->rep_connected = -EIO;
		rpcrdma_conn_func(ep);
		wake_up_all(&ep->rep_connect_wait);
	}
}

static void
rpcrdma_cq_async_error_upcall(struct ib_event *event, void *context)
{
	struct rpcrdma_ep *ep = context;

	pr_err("RPC:       %s: %s on device %s ep %p\n",
	       __func__, ib_event_msg(event->event),
		event->device->name, context);
	if (ep->rep_connected == 1) {
		ep->rep_connected = -EIO;
		rpcrdma_conn_func(ep);
		wake_up_all(&ep->rep_connect_wait);
	}
}

static void
rpcrdma_sendcq_process_wc(struct ib_wc *wc)
{
	/* WARNING: Only wr_id and status are reliable at this point */
	if (wc->wr_id == RPCRDMA_IGNORE_COMPLETION) {
		if (wc->status != IB_WC_SUCCESS &&
		    wc->status != IB_WC_WR_FLUSH_ERR)
			pr_err("RPC:       %s: SEND: %s\n",
			       __func__, ib_wc_status_msg(wc->status));
	} else {
		struct rpcrdma_mw *r;

		r = (struct rpcrdma_mw *)(unsigned long)wc->wr_id;
		r->mw_sendcompletion(wc);
	}
}

static int
rpcrdma_sendcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
{
	struct ib_wc *wcs;
	int budget, count, rc;

	budget = RPCRDMA_WC_BUDGET / RPCRDMA_POLLSIZE;
	do {
		wcs = ep->rep_send_wcs;

		rc = ib_poll_cq(cq, RPCRDMA_POLLSIZE, wcs);
		if (rc <= 0)
			return rc;

		count = rc;
		while (count-- > 0)
			rpcrdma_sendcq_process_wc(wcs++);
	} while (rc == RPCRDMA_POLLSIZE && --budget);
	return 0;
}

/*
 * Handle send, fast_reg_mr, and local_inv completions.
 *
 * Send events are typically suppressed and thus do not result
 * in an upcall. Occasionally one is signaled, however. This
 * prevents the provider's completion queue from wrapping and
 * losing a completion.
 */
static void
rpcrdma_sendcq_upcall(struct ib_cq *cq, void *cq_context)
{
	struct rpcrdma_ep *ep = (struct rpcrdma_ep *)cq_context;
	int rc;

	rc = rpcrdma_sendcq_poll(cq, ep);
	if (rc) {
		dprintk("RPC:       %s: ib_poll_cq failed: %i\n",
			__func__, rc);
		return;
	}

	rc = ib_req_notify_cq(cq,
			IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
	if (rc == 0)
		return;
	if (rc < 0) {
		dprintk("RPC:       %s: ib_req_notify_cq failed: %i\n",
			__func__, rc);
		return;
	}

	rpcrdma_sendcq_poll(cq, ep);
}

static void
rpcrdma_recvcq_process_wc(struct ib_wc *wc, struct list_head *sched_list)
{
	struct rpcrdma_rep *rep =
			(struct rpcrdma_rep *)(unsigned long)wc->wr_id;

	/* WARNING: Only wr_id and status are reliable at this point */
	if (wc->status != IB_WC_SUCCESS)
		goto out_fail;

	/* status == SUCCESS means all fields in wc are trustworthy */
	if (wc->opcode != IB_WC_RECV)
		return;

	dprintk("RPC:       %s: rep %p opcode 'recv', length %u: success\n",
		__func__, rep, wc->byte_len);

	rep->rr_len = wc->byte_len;
	ib_dma_sync_single_for_cpu(rep->rr_device,
				   rdmab_addr(rep->rr_rdmabuf),
				   rep->rr_len, DMA_FROM_DEVICE);
	prefetch(rdmab_to_msg(rep->rr_rdmabuf));

out_schedule:
	list_add_tail(&rep->rr_list, sched_list);
	return;
out_fail:
	if (wc->status != IB_WC_WR_FLUSH_ERR)
		pr_err("RPC:       %s: rep %p: %s\n",
		       __func__, rep, ib_wc_status_msg(wc->status));
	rep->rr_len = ~0U;
	goto out_schedule;
}

static int
rpcrdma_recvcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
{
	struct list_head sched_list;
	struct ib_wc *wcs;
	int budget, count, rc;

	INIT_LIST_HEAD(&sched_list);
	budget = RPCRDMA_WC_BUDGET / RPCRDMA_POLLSIZE;
	do {
		wcs = ep->rep_recv_wcs;

		rc = ib_poll_cq(cq, RPCRDMA_POLLSIZE, wcs);
		if (rc <= 0)
			goto out_schedule;

		count = rc;
		while (count-- > 0)
			rpcrdma_recvcq_process_wc(wcs++, &sched_list);
	} while (rc == RPCRDMA_POLLSIZE && --budget);
	rc = 0;

out_schedule:
	rpcrdma_schedule_tasklet(&sched_list);
	return rc;
}

/*
 * Handle receive completions.
 *
 * It is reentrant but processes single events in order to maintain
 * ordering of receives to keep server credits.
 *
 * It is the responsibility of the scheduled tasklet to return
 * recv buffers to the pool. NOTE: this affects synchronization of
 * connection shutdown. That is, the structures required for
 * the completion of the reply handler must remain intact until
 * all memory has been reclaimed.
 */
static void
rpcrdma_recvcq_upcall(struct ib_cq *cq, void *cq_context)
{
	struct rpcrdma_ep *ep = (struct rpcrdma_ep *)cq_context;
	int rc;

	rc = rpcrdma_recvcq_poll(cq, ep);
	if (rc) {
		dprintk("RPC:       %s: ib_poll_cq failed: %i\n",
			__func__, rc);
		return;
	}

	rc = ib_req_notify_cq(cq,
			IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
	if (rc == 0)
		return;
	if (rc < 0) {
		dprintk("RPC:       %s: ib_req_notify_cq failed: %i\n",
			__func__, rc);
		return;
	}

	rpcrdma_recvcq_poll(cq, ep);
}

static void
rpcrdma_flush_cqs(struct rpcrdma_ep *ep)
{
	struct ib_wc wc;
	LIST_HEAD(sched_list);

	while (ib_poll_cq(ep->rep_attr.recv_cq, 1, &wc) > 0)
		rpcrdma_recvcq_process_wc(&wc, &sched_list);
	if (!list_empty(&sched_list))
		rpcrdma_schedule_tasklet(&sched_list);
	while (ib_poll_cq(ep->rep_attr.send_cq, 1, &wc) > 0)
		rpcrdma_sendcq_process_wc(&wc);
}

static int
rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
{
	struct rpcrdma_xprt *xprt = id->context;
	struct rpcrdma_ia *ia = &xprt->rx_ia;
	struct rpcrdma_ep *ep = &xprt->rx_ep;
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
	struct sockaddr *sap = (struct sockaddr *)&ep->rep_remote_addr;
#endif
	struct ib_qp_attr *attr = &ia->ri_qp_attr;
	struct ib_qp_init_attr *iattr = &ia->ri_qp_init_attr;
	int connstate = 0;

	switch (event->event) {
	case RDMA_CM_EVENT_ADDR_RESOLVED:
	case RDMA_CM_EVENT_ROUTE_RESOLVED:
		ia->ri_async_rc = 0;
		complete(&ia->ri_done);
		break;
	case RDMA_CM_EVENT_ADDR_ERROR:
		ia->ri_async_rc = -EHOSTUNREACH;
		dprintk("RPC:       %s: CM address resolution error, ep 0x%p\n",
			__func__, ep);
		complete(&ia->ri_done);
		break;
	case RDMA_CM_EVENT_ROUTE_ERROR:
		ia->ri_async_rc = -ENETUNREACH;
		dprintk("RPC:       %s: CM route resolution error, ep 0x%p\n",
			__func__, ep);
		complete(&ia->ri_done);
		break;
	case RDMA_CM_EVENT_ESTABLISHED:
		connstate = 1;
		ib_query_qp(ia->ri_id->qp, attr,
			    IB_QP_MAX_QP_RD_ATOMIC | IB_QP_MAX_DEST_RD_ATOMIC,
			    iattr);
		dprintk("RPC:       %s: %d responder resources"
			" (%d initiator)\n",
			__func__, attr->max_dest_rd_atomic,
			attr->max_rd_atomic);
		goto connected;
	case RDMA_CM_EVENT_CONNECT_ERROR:
		connstate = -ENOTCONN;
		goto connected;
	case RDMA_CM_EVENT_UNREACHABLE:
		connstate = -ENETDOWN;
		goto connected;
	case RDMA_CM_EVENT_REJECTED:
		connstate = -ECONNREFUSED;
		goto connected;
	case RDMA_CM_EVENT_DISCONNECTED:
		connstate = -ECONNABORTED;
		goto connected;
	case RDMA_CM_EVENT_DEVICE_REMOVAL:
		connstate = -ENODEV;
connected:
		dprintk("RPC:       %s: %sconnected\n",
					__func__, connstate > 0 ? "" : "dis");
		ep->rep_connected = connstate;
		rpcrdma_conn_func(ep);
		wake_up_all(&ep->rep_connect_wait);
		/*FALLTHROUGH*/
	default:
		dprintk("RPC:       %s: %pIS:%u (ep 0x%p): %s\n",
			__func__, sap, rpc_get_port(sap), ep,
			rdma_event_msg(event->event));
		break;
	}

#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
	if (connstate == 1) {
		int ird = attr->max_dest_rd_atomic;
		int tird = ep->rep_remote_cma.responder_resources;

		pr_info("rpcrdma: connection to %pIS:%u on %s, memreg '%s', %d credits, %d responders%s\n",
			sap, rpc_get_port(sap),
			ia->ri_device->name,
			ia->ri_ops->ro_displayname,
			xprt->rx_buf.rb_max_requests,
			ird, ird < 4 && ird < tird / 2 ? " (low!)" : "");
	} else if (connstate < 0) {
		pr_info("rpcrdma: connection to %pIS:%u closed (%d)\n",
			sap, rpc_get_port(sap), connstate);
	}
#endif

	return 0;
}

static void rpcrdma_destroy_id(struct rdma_cm_id *id)
{
	if (id) {
		module_put(id->device->owner);
		rdma_destroy_id(id);
	}
}

static struct rdma_cm_id *
rpcrdma_create_id(struct rpcrdma_xprt *xprt,
			struct rpcrdma_ia *ia, struct sockaddr *addr)
{
	struct rdma_cm_id *id;
	int rc;

	init_completion(&ia->ri_done);

	id = rdma_create_id(rpcrdma_conn_upcall, xprt, RDMA_PS_TCP, IB_QPT_RC);
	if (IS_ERR(id)) {
		rc = PTR_ERR(id);
		dprintk("RPC:       %s: rdma_create_id() failed %i\n",
			__func__, rc);
		return id;
	}

	ia->ri_async_rc = -ETIMEDOUT;
	rc = rdma_resolve_addr(id, NULL, addr, RDMA_RESOLVE_TIMEOUT);
	if (rc) {
		dprintk("RPC:       %s: rdma_resolve_addr() failed %i\n",
			__func__, rc);
		goto out;
	}
	wait_for_completion_interruptible_timeout(&ia->ri_done,
				msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT) + 1);

	/* FIXME:
	 * Until xprtrdma supports DEVICE_REMOVAL, the provider must
	 * be pinned while there are active NFS/RDMA mounts to prevent
	 * hangs and crashes at umount time.
	 */
	if (!ia->ri_async_rc && !try_module_get(id->device->owner)) {
		dprintk("RPC:       %s: Failed to get device module\n",
			__func__);
		ia->ri_async_rc = -ENODEV;
	}
	rc = ia->ri_async_rc;
	if (rc)
		goto out;

	ia->ri_async_rc = -ETIMEDOUT;
	rc = rdma_resolve_route(id, RDMA_RESOLVE_TIMEOUT);
	if (rc) {
		dprintk("RPC:       %s: rdma_resolve_route() failed %i\n",
			__func__, rc);
		goto put;
	}
	wait_for_completion_interruptible_timeout(&ia->ri_done,
				msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT) + 1);
	rc = ia->ri_async_rc;
	if (rc)
		goto put;

	return id;
put:
	module_put(id->device->owner);
out:
	rdma_destroy_id(id);
	return ERR_PTR(rc);
}

/*
 * Drain any cq, prior to teardown.
 */
static void
rpcrdma_clean_cq(struct ib_cq *cq)
{
	struct ib_wc wc;
	int count = 0;

	while (1 == ib_poll_cq(cq, 1, &wc))
		++count;

	if (count)
		dprintk("RPC:       %s: flushed %d events (last 0x%x)\n",
			__func__, count, wc.opcode);
}

/*
 * Exported functions.
 */

/*
 * Open and initialize an Interface Adapter.
 *  o initializes fields of struct rpcrdma_ia, including
 *    interface and provider attributes and protection zone.
 */
int
rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr, int memreg)
{
	struct rpcrdma_ia *ia = &xprt->rx_ia;
	struct ib_device_attr *devattr = &ia->ri_devattr;
	int rc;

	ia->ri_dma_mr = NULL;

	ia->ri_id = rpcrdma_create_id(xprt, ia, addr);
	if (IS_ERR(ia->ri_id)) {
		rc = PTR_ERR(ia->ri_id);
		goto out1;
	}
	ia->ri_device = ia->ri_id->device;

	ia->ri_pd = ib_alloc_pd(ia->ri_device);
	if (IS_ERR(ia->ri_pd)) {
		rc = PTR_ERR(ia->ri_pd);
		dprintk("RPC:       %s: ib_alloc_pd() failed %i\n",
			__func__, rc);
		goto out2;
	}

	rc = ib_query_device(ia->ri_device, devattr);
	if (rc) {
		dprintk("RPC:       %s: ib_query_device failed %d\n",
			__func__, rc);
		goto out3;
	}

	if (memreg == RPCRDMA_FRMR) {
		/* Requires both frmr reg and local dma lkey */
		if (((devattr->device_cap_flags &
		     (IB_DEVICE_MEM_MGT_EXTENSIONS|IB_DEVICE_LOCAL_DMA_LKEY)) !=
		    (IB_DEVICE_MEM_MGT_EXTENSIONS|IB_DEVICE_LOCAL_DMA_LKEY)) ||
		      (devattr->max_fast_reg_page_list_len == 0)) {
			dprintk("RPC:       %s: FRMR registration "
				"not supported by HCA\n", __func__);
			memreg = RPCRDMA_MTHCAFMR;
		}
	}
	if (memreg == RPCRDMA_MTHCAFMR) {
		if (!ia->ri_device->alloc_fmr) {
			dprintk("RPC:       %s: MTHCAFMR registration "
				"not supported by HCA\n", __func__);
			goto out3;
		}
	}

	switch (memreg) {
	case RPCRDMA_FRMR:
		ia->ri_ops = &rpcrdma_frwr_memreg_ops;
		break;
	case RPCRDMA_ALLPHYSICAL:
		ia->ri_ops = &rpcrdma_physical_memreg_ops;
		break;
	case RPCRDMA_MTHCAFMR:
		ia->ri_ops = &rpcrdma_fmr_memreg_ops;
		break;
	default:
		printk(KERN_ERR "RPC: Unsupported memory "
				"registration mode: %d\n", memreg);
		rc = -ENOMEM;
		goto out3;
	}
	dprintk("RPC:       %s: memory registration strategy is '%s'\n",
		__func__, ia->ri_ops->ro_displayname);

	rwlock_init(&ia->ri_qplock);
	return 0;

out3:
	ib_dealloc_pd(ia->ri_pd);
	ia->ri_pd = NULL;
out2:
	rpcrdma_destroy_id(ia->ri_id);
	ia->ri_id = NULL;
out1:
	return rc;
}

/*
 * Clean up/close an IA.
 *   o if event handles and PD have been initialized, free them.
 *   o close the IA
 */
void
rpcrdma_ia_close(struct rpcrdma_ia *ia)
{
	dprintk("RPC:       %s: entering\n", __func__);
	if (ia->ri_id != NULL && !IS_ERR(ia->ri_id)) {
		if (ia->ri_id->qp)
			rdma_destroy_qp(ia->ri_id);
		rpcrdma_destroy_id(ia->ri_id);
		ia->ri_id = NULL;
	}

	/* If the pd is still busy, xprtrdma missed freeing a resource */
	if (ia->ri_pd && !IS_ERR(ia->ri_pd))
		WARN_ON(ib_dealloc_pd(ia->ri_pd));
}

/*
 * Create unconnected endpoint.
 */
int
rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
				struct rpcrdma_create_data_internal *cdata)
{
	struct ib_device_attr *devattr = &ia->ri_devattr;
	struct ib_cq *sendcq, *recvcq;
	struct ib_cq_init_attr cq_attr = {};
	int rc, err;

	if (devattr->max_sge < RPCRDMA_MAX_IOVS) {
		dprintk("RPC:       %s: insufficient sge's available\n",
			__func__);
		return -ENOMEM;
	}

	/* check provider's send/recv wr limits */
	if (cdata->max_requests > devattr->max_qp_wr)
		cdata->max_requests = devattr->max_qp_wr;

	ep->rep_attr.event_handler = rpcrdma_qp_async_error_upcall;
	ep->rep_attr.qp_context = ep;
	ep->rep_attr.srq = NULL;
	ep->rep_attr.cap.max_send_wr = cdata->max_requests;
	rc = ia->ri_ops->ro_open(ia, ep, cdata);
	if (rc)
		return rc;
	ep->rep_attr.cap.max_recv_wr = cdata->max_requests;
	ep->rep_attr.cap.max_send_sge = RPCRDMA_MAX_IOVS;
	ep->rep_attr.cap.max_recv_sge = 1;
	ep->rep_attr.cap.max_inline_data = 0;
	ep->rep_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
	ep->rep_attr.qp_type = IB_QPT_RC;
	ep->rep_attr.port_num = ~0;

	dprintk("RPC:       %s: requested max: dtos: send %d recv %d; "
		"iovs: send %d recv %d\n",
		__func__,
		ep->rep_attr.cap.max_send_wr,
		ep->rep_attr.cap.max_recv_wr,
		ep->rep_attr.cap.max_send_sge,
		ep->rep_attr.cap.max_recv_sge);

	/* set trigger for requesting send completion */
	ep->rep_cqinit = ep->rep_attr.cap.max_send_wr/2 - 1;
	if (ep->rep_cqinit > RPCRDMA_MAX_UNSIGNALED_SENDS)
		ep->rep_cqinit = RPCRDMA_MAX_UNSIGNALED_SENDS;
	else if (ep->rep_cqinit <= 2)
		ep->rep_cqinit = 0;
	INIT_CQCOUNT(ep);
	init_waitqueue_head(&ep->rep_connect_wait);
	INIT_DELAYED_WORK(&ep->rep_connect_worker, rpcrdma_connect_worker);

	cq_attr.cqe = ep->rep_attr.cap.max_send_wr + 1;
	sendcq = ib_create_cq(ia->ri_device, rpcrdma_sendcq_upcall,
			      rpcrdma_cq_async_error_upcall, ep, &cq_attr);
	if (IS_ERR(sendcq)) {
		rc = PTR_ERR(sendcq);
		dprintk("RPC:       %s: failed to create send CQ: %i\n",
			__func__, rc);
		goto out1;
	}

	rc = ib_req_notify_cq(sendcq, IB_CQ_NEXT_COMP);
	if (rc) {
		dprintk("RPC:       %s: ib_req_notify_cq failed: %i\n",
			__func__, rc);
		goto out2;
	}

	cq_attr.cqe = ep->rep_attr.cap.max_recv_wr + 1;
	recvcq = ib_create_cq(ia->ri_device, rpcrdma_recvcq_upcall,
			      rpcrdma_cq_async_error_upcall, ep, &cq_attr);
	if (IS_ERR(recvcq)) {
		rc = PTR_ERR(recvcq);
		dprintk("RPC:       %s: failed to create recv CQ: %i\n",
			__func__, rc);
		goto out2;
	}

	rc = ib_req_notify_cq(recvcq, IB_CQ_NEXT_COMP);
	if (rc) {
		dprintk("RPC:       %s: ib_req_notify_cq failed: %i\n",
			__func__, rc);
		ib_destroy_cq(recvcq);
		goto out2;
	}

	ep->rep_attr.send_cq = sendcq;
	ep->rep_attr.recv_cq = recvcq;

	/* Initialize cma parameters */

	/* RPC/RDMA does not use private data */
	ep->rep_remote_cma.private_data = NULL;
	ep->rep_remote_cma.private_data_len = 0;

	/* Client offers RDMA Read but does not initiate */
	ep->rep_remote_cma.initiator_depth = 0;
	if (devattr->max_qp_rd_atom > 32)	/* arbitrary but <= 255 */
		ep->rep_remote_cma.responder_resources = 32;
	else
		ep->rep_remote_cma.responder_resources =
						devattr->max_qp_rd_atom;

	ep->rep_remote_cma.retry_count = 7;
	ep->rep_remote_cma.flow_control = 0;
	ep->rep_remote_cma.rnr_retry_count = 0;

	return 0;

out2:
	err = ib_destroy_cq(sendcq);
	if (err)
		dprintk("RPC:       %s: ib_destroy_cq returned %i\n",
			__func__, err);
out1:
	if (ia->ri_dma_mr)
		ib_dereg_mr(ia->ri_dma_mr);
	return rc;
}

/*
 * rpcrdma_ep_destroy
 *
 * Disconnect and destroy endpoint. After this, the only
 * valid operations on the ep are to free it (if dynamically
 * allocated) or re-create it.
 */
void
rpcrdma_ep_destroy(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
{
	int rc;

	dprintk("RPC:       %s: entering, connected is %d\n",
		__func__, ep->rep_connected);

	cancel_delayed_work_sync(&ep->rep_connect_worker);

	if (ia->ri_id->qp) {
		rpcrdma_ep_disconnect(ep, ia);
		rdma_destroy_qp(ia->ri_id);
		ia->ri_id->qp = NULL;
	}

	rpcrdma_clean_cq(ep->rep_attr.recv_cq);
	rc = ib_destroy_cq(ep->rep_attr.recv_cq);
	if (rc)
		dprintk("RPC:       %s: ib_destroy_cq returned %i\n",
			__func__, rc);

	rpcrdma_clean_cq(ep->rep_attr.send_cq);
	rc = ib_destroy_cq(ep->rep_attr.send_cq);
	if (rc)
		dprintk("RPC:       %s: ib_destroy_cq returned %i\n",
			__func__, rc);

	if (ia->ri_dma_mr) {
		rc = ib_dereg_mr(ia->ri_dma_mr);
		dprintk("RPC:       %s: ib_dereg_mr returned %i\n",
			__func__, rc);
	}
}

/*
 * Connect unconnected endpoint.
 */
int
rpcrdma_ep_connect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
{
	struct rdma_cm_id *id, *old;
	int rc = 0;
	int retry_count = 0;

	if (ep->rep_connected != 0) {
		struct rpcrdma_xprt *xprt;
retry:
		dprintk("RPC:       %s: reconnecting...\n", __func__);

		rpcrdma_ep_disconnect(ep, ia);
		rpcrdma_flush_cqs(ep);

		xprt = container_of(ia, struct rpcrdma_xprt, rx_ia);
		id = rpcrdma_create_id(xprt, ia,
				(struct sockaddr *)&xprt->rx_data.addr);
		if (IS_ERR(id)) {
			rc = -EHOSTUNREACH;
			goto out;
		}
		/* TEMP TEMP TEMP - fail if new device:
		 * Deregister/remarshal *all* requests!
		 * Close and recreate adapter, pd, etc!
		 * Re-determine all attributes still sane!
		 * More stuff I haven't thought of!
		 * Rrrgh!
		 */
		if (ia->ri_device != id->device) {
			printk("RPC:       %s: can't reconnect on "
				"different device!\n", __func__);
			rpcrdma_destroy_id(id);
			rc = -ENETUNREACH;
			goto out;
		}
		/* END TEMP */
		rc = rdma_create_qp(id, ia->ri_pd, &ep->rep_attr);
		if (rc) {
			dprintk("RPC:       %s: rdma_create_qp failed %i\n",
				__func__, rc);
			rpcrdma_destroy_id(id);
			rc = -ENETUNREACH;
			goto out;
		}

		write_lock(&ia->ri_qplock);
		old = ia->ri_id;
		ia->ri_id = id;
		write_unlock(&ia->ri_qplock);

		rdma_destroy_qp(old);
		rpcrdma_destroy_id(old);
	} else {
		dprintk("RPC:       %s: connecting...\n", __func__);
		rc = rdma_create_qp(ia->ri_id, ia->ri_pd, &ep->rep_attr);
		if (rc) {
			dprintk("RPC:       %s: rdma_create_qp failed %i\n",
				__func__, rc);
			/* do not update ep->rep_connected */
			return -ENETUNREACH;
		}
	}

	ep->rep_connected = 0;

	rc = rdma_connect(ia->ri_id, &ep->rep_remote_cma);
	if (rc) {
		dprintk("RPC:       %s: rdma_connect() failed with %i\n",
				__func__, rc);
		goto out;
	}

	wait_event_interruptible(ep->rep_connect_wait, ep->rep_connected != 0);

	/*
	 * Check state. A non-peer reject indicates no listener
	 * (ECONNREFUSED), which may be a transient state. All
	 * others indicate a transport condition which has already
	 * undergone a best-effort.
	 */
	if (ep->rep_connected == -ECONNREFUSED &&
	    ++retry_count <= RDMA_CONNECT_RETRY_MAX) {
		dprintk("RPC:       %s: non-peer_reject, retry\n", __func__);
		goto retry;
	}
	if (ep->rep_connected <= 0) {
		/* Sometimes, the only way to reliably connect to remote
		 * CMs is to use same nonzero values for ORD and IRD. */
		if (retry_count++ <= RDMA_CONNECT_RETRY_MAX + 1 &&
		    (ep->rep_remote_cma.responder_resources == 0 ||
		     ep->rep_remote_cma.initiator_depth !=
				ep->rep_remote_cma.responder_resources)) {
			if (ep->rep_remote_cma.responder_resources == 0)
				ep->rep_remote_cma.responder_resources = 1;
			ep->rep_remote_cma.initiator_depth =
				ep->rep_remote_cma.responder_resources;
			goto retry;
		}
		rc = ep->rep_connected;
	} else {
		dprintk("RPC:       %s: connected\n", __func__);
	}

out:
	if (rc)
		ep->rep_connected = rc;
	return rc;
}

/*
 * rpcrdma_ep_disconnect
 *
 * This is separate from destroy to facilitate the ability
 * to reconnect without recreating the endpoint.
 *
 * This call is not reentrant, and must not be made in parallel
 * on the same endpoint.
 */
void
rpcrdma_ep_disconnect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
{
	int rc;

	rpcrdma_flush_cqs(ep);
	rc = rdma_disconnect(ia->ri_id);
	if (!rc) {
		/* returns without wait if not connected */
		wait_event_interruptible(ep->rep_connect_wait,
							ep->rep_connected != 1);
		dprintk("RPC:       %s: after wait, %sconnected\n", __func__,
			(ep->rep_connected == 1) ? "still " : "dis");
	} else {
		dprintk("RPC:       %s: rdma_disconnect %i\n", __func__, rc);
		ep->rep_connected = rc;
	}
}

static struct rpcrdma_req *
rpcrdma_create_req(struct rpcrdma_xprt *r_xprt)
{
	struct rpcrdma_req *req;

	req = kzalloc(sizeof(*req), GFP_KERNEL);
	if (req == NULL)
		return ERR_PTR(-ENOMEM);

	req->rl_buffer = &r_xprt->rx_buf;
	return req;
}

static struct rpcrdma_rep *
rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt)
{
	struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
	struct rpcrdma_rep *rep;
	int rc;

	rc = -ENOMEM;
	rep = kzalloc(sizeof(*rep), GFP_KERNEL);
	if (rep == NULL)
		goto out;

	rep->rr_rdmabuf = rpcrdma_alloc_regbuf(ia, cdata->inline_rsize,
					       GFP_KERNEL);
	if (IS_ERR(rep->rr_rdmabuf)) {
		rc = PTR_ERR(rep->rr_rdmabuf);
		goto out_free;
	}

	rep->rr_device = ia->ri_device;
	rep->rr_rxprt = r_xprt;
	return rep;

out_free:
	kfree(rep);
out:
	return ERR_PTR(rc);
}

int
rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
{
	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
	struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
	char *p;
	size_t len;
	int i, rc;

	buf->rb_max_requests = cdata->max_requests;
	spin_lock_init(&buf->rb_lock);

	/* Need to allocate:
	 *   1.  arrays for send and recv pointers
	 *   2.  arrays of struct rpcrdma_req to fill in pointers
	 *   3.  array of struct rpcrdma_rep for replies
	 * Send/recv buffers in req/rep need to be registered
	 */
	len = buf->rb_max_requests *
		(sizeof(struct rpcrdma_req *) + sizeof(struct rpcrdma_rep *));

	p = kzalloc(len, GFP_KERNEL);
	if (p == NULL) {
		dprintk("RPC:       %s: req_t/rep_t/pad kzalloc(%zd) failed\n",
			__func__, len);
		rc = -ENOMEM;
		goto out;
	}
	buf->rb_pool = p;	/* for freeing it later */

	buf->rb_send_bufs = (struct rpcrdma_req **) p;
	p = (char *) &buf->rb_send_bufs[buf->rb_max_requests];
	buf->rb_recv_bufs = (struct rpcrdma_rep **) p;
	p = (char *) &buf->rb_recv_bufs[buf->rb_max_requests];

	rc = ia->ri_ops->ro_init(r_xprt);
	if (rc)
		goto out;

	for (i = 0; i < buf->rb_max_requests; i++) {
		struct rpcrdma_req *req;
		struct rpcrdma_rep *rep;

		req = rpcrdma_create_req(r_xprt);
		if (IS_ERR(req)) {
			dprintk("RPC:       %s: request buffer %d alloc"
				" failed\n", __func__, i);
			rc = PTR_ERR(req);
			goto out;
		}
		buf->rb_send_bufs[i] = req;

		rep = rpcrdma_create_rep(r_xprt);
		if (IS_ERR(rep)) {
			dprintk("RPC:       %s: reply buffer %d alloc failed\n",
				__func__, i);
			rc = PTR_ERR(rep);
			goto out;
		}
		buf->rb_recv_bufs[i] = rep;
	}

	return 0;
out:
	rpcrdma_buffer_destroy(buf);
	return rc;
}

static void
rpcrdma_destroy_rep(struct rpcrdma_ia *ia, struct rpcrdma_rep *rep)
{
	if (!rep)
		return;

	rpcrdma_free_regbuf(ia, rep->rr_rdmabuf);
	kfree(rep);
}

static void
rpcrdma_destroy_req(struct rpcrdma_ia *ia, struct rpcrdma_req *req)
{
	if (!req)
		return;

	rpcrdma_free_regbuf(ia, req->rl_sendbuf);
	rpcrdma_free_regbuf(ia, req->rl_rdmabuf);
	kfree(req);
}

void
rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf)
{
	struct rpcrdma_ia *ia = rdmab_to_ia(buf);
	int i;

	/* clean up in reverse order from create
	 *   1.  recv mr memory (mr free, then kfree)
	 *   2.  send mr memory (mr free, then kfree)
	 *   3.  MWs
	 */
	dprintk("RPC:       %s: entering\n", __func__);

	for (i = 0; i < buf->rb_max_requests; i++) {
		if (buf->rb_recv_bufs)
			rpcrdma_destroy_rep(ia, buf->rb_recv_bufs[i]);
		if (buf->rb_send_bufs)
			rpcrdma_destroy_req(ia, buf->rb_send_bufs[i]);
	}

	ia->ri_ops->ro_destroy(buf);

	kfree(buf->rb_pool);
}

struct rpcrdma_mw *
rpcrdma_get_mw(struct rpcrdma_xprt *r_xprt)
{
	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
	struct rpcrdma_mw *mw = NULL;

	spin_lock(&buf->rb_mwlock);
	if (!list_empty(&buf->rb_mws)) {
		mw = list_first_entry(&buf->rb_mws,
				      struct rpcrdma_mw, mw_list);
		list_del_init(&mw->mw_list);
	}
	spin_unlock(&buf->rb_mwlock);

	if (!mw)
		pr_err("RPC:       %s: no MWs available\n", __func__);
	return mw;
}

void
rpcrdma_put_mw(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mw *mw)
{
	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;

	spin_lock(&buf->rb_mwlock);
	list_add_tail(&mw->mw_list, &buf->rb_mws);
	spin_unlock(&buf->rb_mwlock);
}

static void
rpcrdma_buffer_put_sendbuf(struct rpcrdma_req *req, struct rpcrdma_buffer *buf)
{
	buf->rb_send_bufs[--buf->rb_send_index] = req;
	req->rl_niovs = 0;
	if (req->rl_reply) {
		buf->rb_recv_bufs[--buf->rb_recv_index] = req->rl_reply;
		req->rl_reply = NULL;
	}
}

/*
 * Get a set of request/reply buffers.
 *
 * Reply buffer (if needed) is attached to send buffer upon return.
 * Rule:
 *    rb_send_index and rb_recv_index MUST always be pointing to the
 *    *next* available buffer (non-NULL). They are incremented after
 *    removing buffers, and decremented *before* returning them.
 */
struct rpcrdma_req *
rpcrdma_buffer_get(struct rpcrdma_buffer *buffers)
{
	struct rpcrdma_req *req;
	unsigned long flags;

	spin_lock_irqsave(&buffers->rb_lock, flags);

	if (buffers->rb_send_index == buffers->rb_max_requests) {
		spin_unlock_irqrestore(&buffers->rb_lock, flags);
		dprintk("RPC:       %s: out of request buffers\n", __func__);
		return ((struct rpcrdma_req *)NULL);
	}

	req = buffers->rb_send_bufs[buffers->rb_send_index];
	if (buffers->rb_send_index < buffers->rb_recv_index) {
		dprintk("RPC:       %s: %d extra receives outstanding (ok)\n",
			__func__,
			buffers->rb_recv_index - buffers->rb_send_index);
		req->rl_reply = NULL;
	} else {
		req->rl_reply = buffers->rb_recv_bufs[buffers->rb_recv_index];
		buffers->rb_recv_bufs[buffers->rb_recv_index++] = NULL;
	}
	buffers->rb_send_bufs[buffers->rb_send_index++] = NULL;

	spin_unlock_irqrestore(&buffers->rb_lock, flags);
	return req;
}

/*
 * Put request/reply buffers back into pool.
 * Pre-decrement counter/array index.
 */
void
rpcrdma_buffer_put(struct rpcrdma_req *req)
{
	struct rpcrdma_buffer *buffers = req->rl_buffer;
	unsigned long flags;

	spin_lock_irqsave(&buffers->rb_lock, flags);
	rpcrdma_buffer_put_sendbuf(req, buffers);
	spin_unlock_irqrestore(&buffers->rb_lock, flags);
}

/*
 * Recover reply buffers from pool.
 * This happens when recovering from error conditions.
 * Post-increment counter/array index.
 */
void
rpcrdma_recv_buffer_get(struct rpcrdma_req *req)
{
	struct rpcrdma_buffer *buffers = req->rl_buffer;
	unsigned long flags;

	spin_lock_irqsave(&buffers->rb_lock, flags);
	if (buffers->rb_recv_index < buffers->rb_max_requests) {
		req->rl_reply = buffers->rb_recv_bufs[buffers->rb_recv_index];
		buffers->rb_recv_bufs[buffers->rb_recv_index++] = NULL;
	}
	spin_unlock_irqrestore(&buffers->rb_lock, flags);
}

/*
 * Put reply buffers back into pool when not attached to
 * request. This happens in error conditions.
 */
void
rpcrdma_recv_buffer_put(struct rpcrdma_rep *rep)
{
	struct rpcrdma_buffer *buffers = &rep->rr_rxprt->rx_buf;
	unsigned long flags;

	spin_lock_irqsave(&buffers->rb_lock, flags);
	buffers->rb_recv_bufs[--buffers->rb_recv_index] = rep;
	spin_unlock_irqrestore(&buffers->rb_lock, flags);
}

/*
 * Wrappers for internal-use kmalloc memory registration, used by buffer code.
 */

void
rpcrdma_mapping_error(struct rpcrdma_mr_seg *seg)
{
	dprintk("RPC:       map_one: offset %p iova %llx len %zu\n",
		seg->mr_offset,
		(unsigned long long)seg->mr_dma, seg->mr_dmalen);
}

/**
 * rpcrdma_alloc_regbuf - kmalloc and register memory for SEND/RECV buffers
 * @ia: controlling rpcrdma_ia
 * @size: size of buffer to be allocated, in bytes
 * @flags: GFP flags
 *
 * Returns pointer to private header of an area of internally
 * registered memory, or an ERR_PTR. The registered buffer follows
 * the end of the private header.
 *
 * xprtrdma uses a regbuf for posting an outgoing RDMA SEND, or for
 * receiving the payload of RDMA RECV operations. regbufs are not
 * used for RDMA READ/WRITE operations, thus are registered only for
 * LOCAL access.
 */
struct rpcrdma_regbuf *
rpcrdma_alloc_regbuf(struct rpcrdma_ia *ia, size_t size, gfp_t flags)
{
	struct rpcrdma_regbuf *rb;
	struct ib_sge *iov;

	rb = kmalloc(sizeof(*rb) + size, flags);
	if (rb == NULL)
		goto out;

	iov = &rb->rg_iov;
	iov->addr = ib_dma_map_single(ia->ri_device,
				      (void *)rb->rg_base, size,
				      DMA_BIDIRECTIONAL);
	if (ib_dma_mapping_error(ia->ri_device, iov->addr))
		goto out_free;

	iov->length = size;
	iov->lkey = ia->ri_dma_lkey;
	rb->rg_size = size;
	rb->rg_owner = NULL;
	return rb;

out_free:
	kfree(rb);
out:
	return ERR_PTR(-ENOMEM);
}

/**
 * rpcrdma_free_regbuf - deregister and free registered buffer
 * @ia: controlling rpcrdma_ia
 * @rb: regbuf to be deregistered and freed
 */
void
rpcrdma_free_regbuf(struct rpcrdma_ia *ia, struct rpcrdma_regbuf *rb)
{
	struct ib_sge *iov;

	if (!rb)
		return;

	iov = &rb->rg_iov;
	ib_dma_unmap_single(ia->ri_device,
			    iov->addr, iov->length, DMA_BIDIRECTIONAL);
	kfree(rb);
}

/*
 * Prepost any receive buffer, then post send.
 *
 * Receive buffer is donated to hardware, reclaimed upon recv completion.
 */
int
rpcrdma_ep_post(struct rpcrdma_ia *ia,
		struct rpcrdma_ep *ep,
		struct rpcrdma_req *req)
{
	struct ib_device *device = ia->ri_device;
	struct ib_send_wr send_wr, *send_wr_fail;
	struct rpcrdma_rep *rep = req->rl_reply;
	struct ib_sge *iov = req->rl_send_iov;
	int i, rc;

	if (rep) {
		rc = rpcrdma_ep_post_recv(ia, ep, rep);
		if (rc)
			goto out;
		req->rl_reply = NULL;
	}

	send_wr.next = NULL;
	send_wr.wr_id = RPCRDMA_IGNORE_COMPLETION;
	send_wr.sg_list = iov;
	send_wr.num_sge = req->rl_niovs;
	send_wr.opcode = IB_WR_SEND;

	for (i = 0; i < send_wr.num_sge; i++)
		ib_dma_sync_single_for_device(device, iov[i].addr,
					      iov[i].length, DMA_TO_DEVICE);
	dprintk("RPC:       %s: posting %d s/g entries\n",
		__func__, send_wr.num_sge);

	if (DECR_CQCOUNT(ep) > 0)
		send_wr.send_flags = 0;
	else { /* Provider must take a send completion every now and then */
		INIT_CQCOUNT(ep);
		send_wr.send_flags = IB_SEND_SIGNALED;
	}

	rc = ib_post_send(ia->ri_id->qp, &send_wr, &send_wr_fail);
	if (rc)
		dprintk("RPC:       %s: ib_post_send returned %i\n", __func__,
			rc);
out:
	return rc;
}

/*
 * (Re)post a receive buffer.
 */
int
rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
		     struct rpcrdma_ep *ep,
		     struct rpcrdma_rep *rep)
{
	struct ib_recv_wr recv_wr, *recv_wr_fail;
	int rc;

	recv_wr.next = NULL;
	recv_wr.wr_id = (u64) (unsigned long) rep;
	recv_wr.sg_list = &rep->rr_rdmabuf->rg_iov;
	recv_wr.num_sge = 1;

	ib_dma_sync_single_for_cpu(ia->ri_device,
				   rdmab_addr(rep->rr_rdmabuf),
				   rdmab_length(rep->rr_rdmabuf),
				   DMA_BIDIRECTIONAL);

	rc = ib_post_recv(ia->ri_id->qp, &recv_wr, &recv_wr_fail);

	if (rc)
		dprintk("RPC:       %s: ib_post_recv returned %i\n", __func__,
			rc);
	return rc;
}

/* How many chunk list items fit within our inline buffers?
 */
unsigned int
rpcrdma_max_segments(struct rpcrdma_xprt *r_xprt)
{
	struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
	int bytes, segments;

	bytes = min_t(unsigned int, cdata->inline_wsize, cdata->inline_rsize);
	bytes -= RPCRDMA_HDRLEN_MIN;
	if (bytes < sizeof(struct rpcrdma_segment) * 2) {
		pr_warn("RPC:       %s: inline threshold too small\n",
			__func__);
		return 0;
	}

	segments = 1 << (fls(bytes / sizeof(struct rpcrdma_segment)) - 1);
	dprintk("RPC:       %s: max chunk list size = %d segments\n",
		__func__, segments);
	return segments;
}