summaryrefslogtreecommitdiffstats
path: root/drivers/infiniband/sw/rxe/rxe_comp.c
blob: d369f24425f94008878b0d9514de16952cbae4af (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
/*
 * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
 * Copyright (c) 2015 System Fabric Works, 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
 * 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/skbuff.h>

#include "rxe.h"
#include "rxe_loc.h"
#include "rxe_queue.h"
#include "rxe_task.h"

enum comp_state {
	COMPST_GET_ACK,
	COMPST_GET_WQE,
	COMPST_COMP_WQE,
	COMPST_COMP_ACK,
	COMPST_CHECK_PSN,
	COMPST_CHECK_ACK,
	COMPST_READ,
	COMPST_ATOMIC,
	COMPST_WRITE_SEND,
	COMPST_UPDATE_COMP,
	COMPST_ERROR_RETRY,
	COMPST_RNR_RETRY,
	COMPST_ERROR,
	COMPST_EXIT, /* We have an issue, and we want to rerun the completer */
	COMPST_DONE, /* The completer finished successflly */
};

static char *comp_state_name[] =  {
	[COMPST_GET_ACK]		= "GET ACK",
	[COMPST_GET_WQE]		= "GET WQE",
	[COMPST_COMP_WQE]		= "COMP WQE",
	[COMPST_COMP_ACK]		= "COMP ACK",
	[COMPST_CHECK_PSN]		= "CHECK PSN",
	[COMPST_CHECK_ACK]		= "CHECK ACK",
	[COMPST_READ]			= "READ",
	[COMPST_ATOMIC]			= "ATOMIC",
	[COMPST_WRITE_SEND]		= "WRITE/SEND",
	[COMPST_UPDATE_COMP]		= "UPDATE COMP",
	[COMPST_ERROR_RETRY]		= "ERROR RETRY",
	[COMPST_RNR_RETRY]		= "RNR RETRY",
	[COMPST_ERROR]			= "ERROR",
	[COMPST_EXIT]			= "EXIT",
	[COMPST_DONE]			= "DONE",
};

static unsigned long rnrnak_usec[32] = {
	[IB_RNR_TIMER_655_36] = 655360,
	[IB_RNR_TIMER_000_01] = 10,
	[IB_RNR_TIMER_000_02] = 20,
	[IB_RNR_TIMER_000_03] = 30,
	[IB_RNR_TIMER_000_04] = 40,
	[IB_RNR_TIMER_000_06] = 60,
	[IB_RNR_TIMER_000_08] = 80,
	[IB_RNR_TIMER_000_12] = 120,
	[IB_RNR_TIMER_000_16] = 160,
	[IB_RNR_TIMER_000_24] = 240,
	[IB_RNR_TIMER_000_32] = 320,
	[IB_RNR_TIMER_000_48] = 480,
	[IB_RNR_TIMER_000_64] = 640,
	[IB_RNR_TIMER_000_96] = 960,
	[IB_RNR_TIMER_001_28] = 1280,
	[IB_RNR_TIMER_001_92] = 1920,
	[IB_RNR_TIMER_002_56] = 2560,
	[IB_RNR_TIMER_003_84] = 3840,
	[IB_RNR_TIMER_005_12] = 5120,
	[IB_RNR_TIMER_007_68] = 7680,
	[IB_RNR_TIMER_010_24] = 10240,
	[IB_RNR_TIMER_015_36] = 15360,
	[IB_RNR_TIMER_020_48] = 20480,
	[IB_RNR_TIMER_030_72] = 30720,
	[IB_RNR_TIMER_040_96] = 40960,
	[IB_RNR_TIMER_061_44] = 61410,
	[IB_RNR_TIMER_081_92] = 81920,
	[IB_RNR_TIMER_122_88] = 122880,
	[IB_RNR_TIMER_163_84] = 163840,
	[IB_RNR_TIMER_245_76] = 245760,
	[IB_RNR_TIMER_327_68] = 327680,
	[IB_RNR_TIMER_491_52] = 491520,
};

static inline unsigned long rnrnak_jiffies(u8 timeout)
{
	return max_t(unsigned long,
		usecs_to_jiffies(rnrnak_usec[timeout]), 1);
}

static enum ib_wc_opcode wr_to_wc_opcode(enum ib_wr_opcode opcode)
{
	switch (opcode) {
	case IB_WR_RDMA_WRITE:			return IB_WC_RDMA_WRITE;
	case IB_WR_RDMA_WRITE_WITH_IMM:		return IB_WC_RDMA_WRITE;
	case IB_WR_SEND:			return IB_WC_SEND;
	case IB_WR_SEND_WITH_IMM:		return IB_WC_SEND;
	case IB_WR_RDMA_READ:			return IB_WC_RDMA_READ;
	case IB_WR_ATOMIC_CMP_AND_SWP:		return IB_WC_COMP_SWAP;
	case IB_WR_ATOMIC_FETCH_AND_ADD:	return IB_WC_FETCH_ADD;
	case IB_WR_LSO:				return IB_WC_LSO;
	case IB_WR_SEND_WITH_INV:		return IB_WC_SEND;
	case IB_WR_RDMA_READ_WITH_INV:		return IB_WC_RDMA_READ;
	case IB_WR_LOCAL_INV:			return IB_WC_LOCAL_INV;
	case IB_WR_REG_MR:			return IB_WC_REG_MR;

	default:
		return 0xff;
	}
}

void retransmit_timer(unsigned long data)
{
	struct rxe_qp *qp = (struct rxe_qp *)data;

	if (qp->valid) {
		qp->comp.timeout = 1;
		rxe_run_task(&qp->comp.task, 1);
	}
}

void rxe_comp_queue_pkt(struct rxe_dev *rxe, struct rxe_qp *qp,
			struct sk_buff *skb)
{
	int must_sched;

	skb_queue_tail(&qp->resp_pkts, skb);

	must_sched = skb_queue_len(&qp->resp_pkts) > 1;
	rxe_run_task(&qp->comp.task, must_sched);
}

static inline enum comp_state get_wqe(struct rxe_qp *qp,
				      struct rxe_pkt_info *pkt,
				      struct rxe_send_wqe **wqe_p)
{
	struct rxe_send_wqe *wqe;

	/* we come here whether or not we found a response packet to see if
	 * there are any posted WQEs
	 */
	wqe = queue_head(qp->sq.queue);
	*wqe_p = wqe;

	/* no WQE or requester has not started it yet */
	if (!wqe || wqe->state == wqe_state_posted)
		return pkt ? COMPST_DONE : COMPST_EXIT;

	/* WQE does not require an ack */
	if (wqe->state == wqe_state_done)
		return COMPST_COMP_WQE;

	/* WQE caused an error */
	if (wqe->state == wqe_state_error)
		return COMPST_ERROR;

	/* we have a WQE, if we also have an ack check its PSN */
	return pkt ? COMPST_CHECK_PSN : COMPST_EXIT;
}

static inline void reset_retry_counters(struct rxe_qp *qp)
{
	qp->comp.retry_cnt = qp->attr.retry_cnt;
	qp->comp.rnr_retry = qp->attr.rnr_retry;
}

static inline enum comp_state check_psn(struct rxe_qp *qp,
					struct rxe_pkt_info *pkt,
					struct rxe_send_wqe *wqe)
{
	s32 diff;

	/* check to see if response is past the oldest WQE. if it is, complete
	 * send/write or error read/atomic
	 */
	diff = psn_compare(pkt->psn, wqe->last_psn);
	if (diff > 0) {
		if (wqe->state == wqe_state_pending) {
			if (wqe->mask & WR_ATOMIC_OR_READ_MASK)
				return COMPST_ERROR_RETRY;

			reset_retry_counters(qp);
			return COMPST_COMP_WQE;
		} else {
			return COMPST_DONE;
		}
	}

	/* compare response packet to expected response */
	diff = psn_compare(pkt->psn, qp->comp.psn);
	if (diff < 0) {
		/* response is most likely a retried packet if it matches an
		 * uncompleted WQE go complete it else ignore it
		 */
		if (pkt->psn == wqe->last_psn)
			return COMPST_COMP_ACK;
		else
			return COMPST_DONE;
	} else if ((diff > 0) && (wqe->mask & WR_ATOMIC_OR_READ_MASK)) {
		return COMPST_DONE;
	} else {
		return COMPST_CHECK_ACK;
	}
}

static inline enum comp_state check_ack(struct rxe_qp *qp,
					struct rxe_pkt_info *pkt,
					struct rxe_send_wqe *wqe)
{
	unsigned int mask = pkt->mask;
	u8 syn;

	/* Check the sequence only */
	switch (qp->comp.opcode) {
	case -1:
		/* Will catch all *_ONLY cases. */
		if (!(mask & RXE_START_MASK))
			return COMPST_ERROR;

		break;

	case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
	case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
		if (pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE &&
		    pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST) {
			return COMPST_ERROR;
		}
		break;
	default:
		WARN_ON(1);
	}

	/* Check operation validity. */
	switch (pkt->opcode) {
	case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
	case IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST:
	case IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY:
		syn = aeth_syn(pkt);

		if ((syn & AETH_TYPE_MASK) != AETH_ACK)
			return COMPST_ERROR;

		/* Fall through (IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE
		 * doesn't have an AETH)
		 */
	case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
		if (wqe->wr.opcode != IB_WR_RDMA_READ &&
		    wqe->wr.opcode != IB_WR_RDMA_READ_WITH_INV) {
			return COMPST_ERROR;
		}
		reset_retry_counters(qp);
		return COMPST_READ;

	case IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE:
		syn = aeth_syn(pkt);

		if ((syn & AETH_TYPE_MASK) != AETH_ACK)
			return COMPST_ERROR;

		if (wqe->wr.opcode != IB_WR_ATOMIC_CMP_AND_SWP &&
		    wqe->wr.opcode != IB_WR_ATOMIC_FETCH_AND_ADD)
			return COMPST_ERROR;
		reset_retry_counters(qp);
		return COMPST_ATOMIC;

	case IB_OPCODE_RC_ACKNOWLEDGE:
		syn = aeth_syn(pkt);
		switch (syn & AETH_TYPE_MASK) {
		case AETH_ACK:
			reset_retry_counters(qp);
			return COMPST_WRITE_SEND;

		case AETH_RNR_NAK:
			return COMPST_RNR_RETRY;

		case AETH_NAK:
			switch (syn) {
			case AETH_NAK_PSN_SEQ_ERROR:
				/* a nak implicitly acks all packets with psns
				 * before
				 */
				if (psn_compare(pkt->psn, qp->comp.psn) > 0) {
					qp->comp.psn = pkt->psn;
					if (qp->req.wait_psn) {
						qp->req.wait_psn = 0;
						rxe_run_task(&qp->req.task, 1);
					}
				}
				return COMPST_ERROR_RETRY;

			case AETH_NAK_INVALID_REQ:
				wqe->status = IB_WC_REM_INV_REQ_ERR;
				return COMPST_ERROR;

			case AETH_NAK_REM_ACC_ERR:
				wqe->status = IB_WC_REM_ACCESS_ERR;
				return COMPST_ERROR;

			case AETH_NAK_REM_OP_ERR:
				wqe->status = IB_WC_REM_OP_ERR;
				return COMPST_ERROR;

			default:
				pr_warn("unexpected nak %x\n", syn);
				wqe->status = IB_WC_REM_OP_ERR;
				return COMPST_ERROR;
			}

		default:
			return COMPST_ERROR;
		}
		break;

	default:
		pr_warn("unexpected opcode\n");
	}

	return COMPST_ERROR;
}

static inline enum comp_state do_read(struct rxe_qp *qp,
				      struct rxe_pkt_info *pkt,
				      struct rxe_send_wqe *wqe)
{
	struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
	int ret;

	ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
			&wqe->dma, payload_addr(pkt),
			payload_size(pkt), to_mem_obj, NULL);
	if (ret)
		return COMPST_ERROR;

	if (wqe->dma.resid == 0 && (pkt->mask & RXE_END_MASK))
		return COMPST_COMP_ACK;
	else
		return COMPST_UPDATE_COMP;
}

static inline enum comp_state do_atomic(struct rxe_qp *qp,
					struct rxe_pkt_info *pkt,
					struct rxe_send_wqe *wqe)
{
	struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
	int ret;

	u64 atomic_orig = atmack_orig(pkt);

	ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
			&wqe->dma, &atomic_orig,
			sizeof(u64), to_mem_obj, NULL);
	if (ret)
		return COMPST_ERROR;
	else
		return COMPST_COMP_ACK;
}

static void make_send_cqe(struct rxe_qp *qp, struct rxe_send_wqe *wqe,
			  struct rxe_cqe *cqe)
{
	memset(cqe, 0, sizeof(*cqe));

	if (!qp->is_user) {
		struct ib_wc		*wc	= &cqe->ibwc;

		wc->wr_id		= wqe->wr.wr_id;
		wc->status		= wqe->status;
		wc->opcode		= wr_to_wc_opcode(wqe->wr.opcode);
		if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
		    wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
			wc->wc_flags = IB_WC_WITH_IMM;
		wc->byte_len		= wqe->dma.length;
		wc->qp			= &qp->ibqp;
	} else {
		struct ib_uverbs_wc	*uwc	= &cqe->uibwc;

		uwc->wr_id		= wqe->wr.wr_id;
		uwc->status		= wqe->status;
		uwc->opcode		= wr_to_wc_opcode(wqe->wr.opcode);
		if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
		    wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
			uwc->wc_flags = IB_WC_WITH_IMM;
		uwc->byte_len		= wqe->dma.length;
		uwc->qp_num		= qp->ibqp.qp_num;
	}
}

static void do_complete(struct rxe_qp *qp, struct rxe_send_wqe *wqe)
{
	struct rxe_cqe cqe;

	if ((qp->sq_sig_type == IB_SIGNAL_ALL_WR) ||
	    (wqe->wr.send_flags & IB_SEND_SIGNALED) ||
	    (qp->req.state == QP_STATE_ERROR)) {
		make_send_cqe(qp, wqe, &cqe);
		advance_consumer(qp->sq.queue);
		rxe_cq_post(qp->scq, &cqe, 0);
	} else {
		advance_consumer(qp->sq.queue);
	}

	/*
	 * we completed something so let req run again
	 * if it is trying to fence
	 */
	if (qp->req.wait_fence) {
		qp->req.wait_fence = 0;
		rxe_run_task(&qp->req.task, 1);
	}
}

static inline enum comp_state complete_ack(struct rxe_qp *qp,
					   struct rxe_pkt_info *pkt,
					   struct rxe_send_wqe *wqe)
{
	unsigned long flags;

	if (wqe->has_rd_atomic) {
		wqe->has_rd_atomic = 0;
		atomic_inc(&qp->req.rd_atomic);
		if (qp->req.need_rd_atomic) {
			qp->comp.timeout_retry = 0;
			qp->req.need_rd_atomic = 0;
			rxe_run_task(&qp->req.task, 1);
		}
	}

	if (unlikely(qp->req.state == QP_STATE_DRAIN)) {
		/* state_lock used by requester & completer */
		spin_lock_irqsave(&qp->state_lock, flags);
		if ((qp->req.state == QP_STATE_DRAIN) &&
		    (qp->comp.psn == qp->req.psn)) {
			qp->req.state = QP_STATE_DRAINED;
			spin_unlock_irqrestore(&qp->state_lock, flags);

			if (qp->ibqp.event_handler) {
				struct ib_event ev;

				ev.device = qp->ibqp.device;
				ev.element.qp = &qp->ibqp;
				ev.event = IB_EVENT_SQ_DRAINED;
				qp->ibqp.event_handler(&ev,
					qp->ibqp.qp_context);
			}
		} else {
			spin_unlock_irqrestore(&qp->state_lock, flags);
		}
	}

	do_complete(qp, wqe);

	if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
		return COMPST_UPDATE_COMP;
	else
		return COMPST_DONE;
}

static inline enum comp_state complete_wqe(struct rxe_qp *qp,
					   struct rxe_pkt_info *pkt,
					   struct rxe_send_wqe *wqe)
{
	qp->comp.opcode = -1;

	if (pkt) {
		if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
			qp->comp.psn = (pkt->psn + 1) & BTH_PSN_MASK;

		if (qp->req.wait_psn) {
			qp->req.wait_psn = 0;
			rxe_run_task(&qp->req.task, 1);
		}
	}

	do_complete(qp, wqe);

	return COMPST_GET_WQE;
}

int rxe_completer(void *arg)
{
	struct rxe_qp *qp = (struct rxe_qp *)arg;
	struct rxe_send_wqe *wqe = wqe;
	struct sk_buff *skb = NULL;
	struct rxe_pkt_info *pkt = NULL;
	enum comp_state state;

	rxe_add_ref(qp);

	if (!qp->valid) {
		while ((skb = skb_dequeue(&qp->resp_pkts))) {
			rxe_drop_ref(qp);
			kfree_skb(skb);
		}
		skb = NULL;
		pkt = NULL;

		while (queue_head(qp->sq.queue))
			advance_consumer(qp->sq.queue);

		goto exit;
	}

	if (qp->req.state == QP_STATE_ERROR) {
		while ((skb = skb_dequeue(&qp->resp_pkts))) {
			rxe_drop_ref(qp);
			kfree_skb(skb);
		}
		skb = NULL;
		pkt = NULL;

		while ((wqe = queue_head(qp->sq.queue))) {
			wqe->status = IB_WC_WR_FLUSH_ERR;
			do_complete(qp, wqe);
		}

		goto exit;
	}

	if (qp->req.state == QP_STATE_RESET) {
		while ((skb = skb_dequeue(&qp->resp_pkts))) {
			rxe_drop_ref(qp);
			kfree_skb(skb);
		}
		skb = NULL;
		pkt = NULL;

		while (queue_head(qp->sq.queue))
			advance_consumer(qp->sq.queue);

		goto exit;
	}

	if (qp->comp.timeout) {
		qp->comp.timeout_retry = 1;
		qp->comp.timeout = 0;
	} else {
		qp->comp.timeout_retry = 0;
	}

	if (qp->req.need_retry)
		goto exit;

	state = COMPST_GET_ACK;

	while (1) {
		pr_debug("qp#%d state = %s\n", qp_num(qp),
			 comp_state_name[state]);
		switch (state) {
		case COMPST_GET_ACK:
			skb = skb_dequeue(&qp->resp_pkts);
			if (skb) {
				pkt = SKB_TO_PKT(skb);
				qp->comp.timeout_retry = 0;
			}
			state = COMPST_GET_WQE;
			break;

		case COMPST_GET_WQE:
			state = get_wqe(qp, pkt, &wqe);
			break;

		case COMPST_CHECK_PSN:
			state = check_psn(qp, pkt, wqe);
			break;

		case COMPST_CHECK_ACK:
			state = check_ack(qp, pkt, wqe);
			break;

		case COMPST_READ:
			state = do_read(qp, pkt, wqe);
			break;

		case COMPST_ATOMIC:
			state = do_atomic(qp, pkt, wqe);
			break;

		case COMPST_WRITE_SEND:
			if (wqe->state == wqe_state_pending &&
			    wqe->last_psn == pkt->psn)
				state = COMPST_COMP_ACK;
			else
				state = COMPST_UPDATE_COMP;
			break;

		case COMPST_COMP_ACK:
			state = complete_ack(qp, pkt, wqe);
			break;

		case COMPST_COMP_WQE:
			state = complete_wqe(qp, pkt, wqe);
			break;

		case COMPST_UPDATE_COMP:
			if (pkt->mask & RXE_END_MASK)
				qp->comp.opcode = -1;
			else
				qp->comp.opcode = pkt->opcode;

			if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
				qp->comp.psn = (pkt->psn + 1) & BTH_PSN_MASK;

			if (qp->req.wait_psn) {
				qp->req.wait_psn = 0;
				rxe_run_task(&qp->req.task, 1);
			}

			state = COMPST_DONE;
			break;

		case COMPST_DONE:
			if (pkt) {
				rxe_drop_ref(pkt->qp);
				kfree_skb(skb);
			}
			goto done;

		case COMPST_EXIT:
			if (qp->comp.timeout_retry && wqe) {
				state = COMPST_ERROR_RETRY;
				break;
			}

			/* re reset the timeout counter if
			 * (1) QP is type RC
			 * (2) the QP is alive
			 * (3) there is a packet sent by the requester that
			 *     might be acked (we still might get spurious
			 *     timeouts but try to keep them as few as possible)
			 * (4) the timeout parameter is set
			 */
			if ((qp_type(qp) == IB_QPT_RC) &&
			    (qp->req.state == QP_STATE_READY) &&
			    (psn_compare(qp->req.psn, qp->comp.psn) > 0) &&
			    qp->qp_timeout_jiffies)
				mod_timer(&qp->retrans_timer,
					  jiffies + qp->qp_timeout_jiffies);
			goto exit;

		case COMPST_ERROR_RETRY:
			/* we come here if the retry timer fired and we did
			 * not receive a response packet. try to retry the send
			 * queue if that makes sense and the limits have not
			 * been exceeded. remember that some timeouts are
			 * spurious since we do not reset the timer but kick
			 * it down the road or let it expire
			 */

			/* there is nothing to retry in this case */
			if (!wqe || (wqe->state == wqe_state_posted))
				goto exit;

			if (qp->comp.retry_cnt > 0) {
				if (qp->comp.retry_cnt != 7)
					qp->comp.retry_cnt--;

				/* no point in retrying if we have already
				 * seen the last ack that the requester could
				 * have caused
				 */
				if (psn_compare(qp->req.psn,
						qp->comp.psn) > 0) {
					/* tell the requester to retry the
					 * send send queue next time around
					 */
					qp->req.need_retry = 1;
					rxe_run_task(&qp->req.task, 1);
				}

				if (pkt) {
					rxe_drop_ref(pkt->qp);
					kfree_skb(skb);
				}

				goto exit;

			} else {
				wqe->status = IB_WC_RETRY_EXC_ERR;
				state = COMPST_ERROR;
			}
			break;

		case COMPST_RNR_RETRY:
			if (qp->comp.rnr_retry > 0) {
				if (qp->comp.rnr_retry != 7)
					qp->comp.rnr_retry--;

				qp->req.need_retry = 1;
				pr_debug("qp#%d set rnr nak timer\n",
					 qp_num(qp));
				mod_timer(&qp->rnr_nak_timer,
					  jiffies + rnrnak_jiffies(aeth_syn(pkt)
						& ~AETH_TYPE_MASK));
				goto exit;
			} else {
				wqe->status = IB_WC_RNR_RETRY_EXC_ERR;
				state = COMPST_ERROR;
			}
			break;

		case COMPST_ERROR:
			do_complete(qp, wqe);
			rxe_qp_error(qp);

			if (pkt) {
				rxe_drop_ref(pkt->qp);
				kfree_skb(skb);
			}

			goto exit;
		}
	}

exit:
	/* we come here if we are done with processing and want the task to
	 * exit from the loop calling us
	 */
	rxe_drop_ref(qp);
	return -EAGAIN;

done:
	/* we come here if we have processed a packet we want the task to call
	 * us again to see if there is anything else to do
	 */
	rxe_drop_ref(qp);
	return 0;
}