summaryrefslogtreecommitdiffstats
path: root/drivers/scsi/scsi_transport_srp.c
blob: ae45bd99baed72662b1c528aef97f3b49e9aeb6a (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
/*
 * SCSI RDMA (SRP) transport class
 *
 * Copyright (C) 2007 FUJITA Tomonori <tomof@acm.org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2 of the
 * License.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/jiffies.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/delay.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_transport_srp.h>
#include "scsi_priv.h"

struct srp_host_attrs {
	atomic_t next_port_id;
};
#define to_srp_host_attrs(host)	((struct srp_host_attrs *)(host)->shost_data)

#define SRP_HOST_ATTRS 0
#define SRP_RPORT_ATTRS 8

struct srp_internal {
	struct scsi_transport_template t;
	struct srp_function_template *f;

	struct device_attribute *host_attrs[SRP_HOST_ATTRS + 1];

	struct device_attribute *rport_attrs[SRP_RPORT_ATTRS + 1];
	struct transport_container rport_attr_cont;
};

#define to_srp_internal(tmpl) container_of(tmpl, struct srp_internal, t)

#define	dev_to_rport(d)	container_of(d, struct srp_rport, dev)
#define transport_class_to_srp_rport(dev) dev_to_rport((dev)->parent)
static inline struct Scsi_Host *rport_to_shost(struct srp_rport *r)
{
	return dev_to_shost(r->dev.parent);
}

/**
 * srp_tmo_valid() - check timeout combination validity
 * @reconnect_delay: Reconnect delay in seconds.
 * @fast_io_fail_tmo: Fast I/O fail timeout in seconds.
 * @dev_loss_tmo: Device loss timeout in seconds.
 *
 * The combination of the timeout parameters must be such that SCSI commands
 * are finished in a reasonable time. Hence do not allow the fast I/O fail
 * timeout to exceed SCSI_DEVICE_BLOCK_MAX_TIMEOUT nor allow dev_loss_tmo to
 * exceed that limit if failing I/O fast has been disabled. Furthermore, these
 * parameters must be such that multipath can detect failed paths timely.
 * Hence do not allow all three parameters to be disabled simultaneously.
 */
int srp_tmo_valid(int reconnect_delay, int fast_io_fail_tmo, int dev_loss_tmo)
{
	if (reconnect_delay < 0 && fast_io_fail_tmo < 0 && dev_loss_tmo < 0)
		return -EINVAL;
	if (reconnect_delay == 0)
		return -EINVAL;
	if (fast_io_fail_tmo > SCSI_DEVICE_BLOCK_MAX_TIMEOUT)
		return -EINVAL;
	if (fast_io_fail_tmo < 0 &&
	    dev_loss_tmo > SCSI_DEVICE_BLOCK_MAX_TIMEOUT)
		return -EINVAL;
	if (dev_loss_tmo >= LONG_MAX / HZ)
		return -EINVAL;
	if (fast_io_fail_tmo >= 0 && dev_loss_tmo >= 0 &&
	    fast_io_fail_tmo >= dev_loss_tmo)
		return -EINVAL;
	return 0;
}
EXPORT_SYMBOL_GPL(srp_tmo_valid);

static int srp_host_setup(struct transport_container *tc, struct device *dev,
			  struct device *cdev)
{
	struct Scsi_Host *shost = dev_to_shost(dev);
	struct srp_host_attrs *srp_host = to_srp_host_attrs(shost);

	atomic_set(&srp_host->next_port_id, 0);
	return 0;
}

static DECLARE_TRANSPORT_CLASS(srp_host_class, "srp_host", srp_host_setup,
			       NULL, NULL);

static DECLARE_TRANSPORT_CLASS(srp_rport_class, "srp_remote_ports",
			       NULL, NULL, NULL);

#define SRP_PID(p) \
	(p)->port_id[0], (p)->port_id[1], (p)->port_id[2], (p)->port_id[3], \
	(p)->port_id[4], (p)->port_id[5], (p)->port_id[6], (p)->port_id[7], \
	(p)->port_id[8], (p)->port_id[9], (p)->port_id[10], (p)->port_id[11], \
	(p)->port_id[12], (p)->port_id[13], (p)->port_id[14], (p)->port_id[15]

#define SRP_PID_FMT "%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x:" \
	"%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x"

static ssize_t
show_srp_rport_id(struct device *dev, struct device_attribute *attr,
		  char *buf)
{
	struct srp_rport *rport = transport_class_to_srp_rport(dev);
	return sprintf(buf, SRP_PID_FMT "\n", SRP_PID(rport));
}

static DEVICE_ATTR(port_id, S_IRUGO, show_srp_rport_id, NULL);

static const struct {
	u32 value;
	char *name;
} srp_rport_role_names[] = {
	{SRP_RPORT_ROLE_INITIATOR, "SRP Initiator"},
	{SRP_RPORT_ROLE_TARGET, "SRP Target"},
};

static ssize_t
show_srp_rport_roles(struct device *dev, struct device_attribute *attr,
		     char *buf)
{
	struct srp_rport *rport = transport_class_to_srp_rport(dev);
	int i;
	char *name = NULL;

	for (i = 0; i < ARRAY_SIZE(srp_rport_role_names); i++)
		if (srp_rport_role_names[i].value == rport->roles) {
			name = srp_rport_role_names[i].name;
			break;
		}
	return sprintf(buf, "%s\n", name ? : "unknown");
}

static DEVICE_ATTR(roles, S_IRUGO, show_srp_rport_roles, NULL);

static ssize_t store_srp_rport_delete(struct device *dev,
				      struct device_attribute *attr,
				      const char *buf, size_t count)
{
	struct srp_rport *rport = transport_class_to_srp_rport(dev);
	struct Scsi_Host *shost = dev_to_shost(dev);
	struct srp_internal *i = to_srp_internal(shost->transportt);

	if (i->f->rport_delete) {
		i->f->rport_delete(rport);
		return count;
	} else {
		return -ENOSYS;
	}
}

static DEVICE_ATTR(delete, S_IWUSR, NULL, store_srp_rport_delete);

static ssize_t show_srp_rport_state(struct device *dev,
				    struct device_attribute *attr,
				    char *buf)
{
	static const char *const state_name[] = {
		[SRP_RPORT_RUNNING]	= "running",
		[SRP_RPORT_BLOCKED]	= "blocked",
		[SRP_RPORT_FAIL_FAST]	= "fail-fast",
		[SRP_RPORT_LOST]	= "lost",
	};
	struct srp_rport *rport = transport_class_to_srp_rport(dev);
	enum srp_rport_state state = rport->state;

	return sprintf(buf, "%s\n",
		       (unsigned)state < ARRAY_SIZE(state_name) ?
		       state_name[state] : "???");
}

static DEVICE_ATTR(state, S_IRUGO, show_srp_rport_state, NULL);

static ssize_t srp_show_tmo(char *buf, int tmo)
{
	return tmo >= 0 ? sprintf(buf, "%d\n", tmo) : sprintf(buf, "off\n");
}

static int srp_parse_tmo(int *tmo, const char *buf)
{
	int res = 0;

	if (strncmp(buf, "off", 3) != 0)
		res = kstrtoint(buf, 0, tmo);
	else
		*tmo = -1;

	return res;
}

static ssize_t show_reconnect_delay(struct device *dev,
				    struct device_attribute *attr, char *buf)
{
	struct srp_rport *rport = transport_class_to_srp_rport(dev);

	return srp_show_tmo(buf, rport->reconnect_delay);
}

static ssize_t store_reconnect_delay(struct device *dev,
				     struct device_attribute *attr,
				     const char *buf, const size_t count)
{
	struct srp_rport *rport = transport_class_to_srp_rport(dev);
	int res, delay;

	res = srp_parse_tmo(&delay, buf);
	if (res)
		goto out;
	res = srp_tmo_valid(delay, rport->fast_io_fail_tmo,
			    rport->dev_loss_tmo);
	if (res)
		goto out;

	if (rport->reconnect_delay <= 0 && delay > 0 &&
	    rport->state != SRP_RPORT_RUNNING) {
		queue_delayed_work(system_long_wq, &rport->reconnect_work,
				   delay * HZ);
	} else if (delay <= 0) {
		cancel_delayed_work(&rport->reconnect_work);
	}
	rport->reconnect_delay = delay;
	res = count;

out:
	return res;
}

static DEVICE_ATTR(reconnect_delay, S_IRUGO | S_IWUSR, show_reconnect_delay,
		   store_reconnect_delay);

static ssize_t show_failed_reconnects(struct device *dev,
				      struct device_attribute *attr, char *buf)
{
	struct srp_rport *rport = transport_class_to_srp_rport(dev);

	return sprintf(buf, "%d\n", rport->failed_reconnects);
}

static DEVICE_ATTR(failed_reconnects, S_IRUGO, show_failed_reconnects, NULL);

static ssize_t show_srp_rport_fast_io_fail_tmo(struct device *dev,
					       struct device_attribute *attr,
					       char *buf)
{
	struct srp_rport *rport = transport_class_to_srp_rport(dev);

	return srp_show_tmo(buf, rport->fast_io_fail_tmo);
}

static ssize_t store_srp_rport_fast_io_fail_tmo(struct device *dev,
						struct device_attribute *attr,
						const char *buf, size_t count)
{
	struct srp_rport *rport = transport_class_to_srp_rport(dev);
	int res;
	int fast_io_fail_tmo;

	res = srp_parse_tmo(&fast_io_fail_tmo, buf);
	if (res)
		goto out;
	res = srp_tmo_valid(rport->reconnect_delay, fast_io_fail_tmo,
			    rport->dev_loss_tmo);
	if (res)
		goto out;
	rport->fast_io_fail_tmo = fast_io_fail_tmo;
	res = count;

out:
	return res;
}

static DEVICE_ATTR(fast_io_fail_tmo, S_IRUGO | S_IWUSR,
		   show_srp_rport_fast_io_fail_tmo,
		   store_srp_rport_fast_io_fail_tmo);

static ssize_t show_srp_rport_dev_loss_tmo(struct device *dev,
					   struct device_attribute *attr,
					   char *buf)
{
	struct srp_rport *rport = transport_class_to_srp_rport(dev);

	return srp_show_tmo(buf, rport->dev_loss_tmo);
}

static ssize_t store_srp_rport_dev_loss_tmo(struct device *dev,
					    struct device_attribute *attr,
					    const char *buf, size_t count)
{
	struct srp_rport *rport = transport_class_to_srp_rport(dev);
	int res;
	int dev_loss_tmo;

	res = srp_parse_tmo(&dev_loss_tmo, buf);
	if (res)
		goto out;
	res = srp_tmo_valid(rport->reconnect_delay, rport->fast_io_fail_tmo,
			    dev_loss_tmo);
	if (res)
		goto out;
	rport->dev_loss_tmo = dev_loss_tmo;
	res = count;

out:
	return res;
}

static DEVICE_ATTR(dev_loss_tmo, S_IRUGO | S_IWUSR,
		   show_srp_rport_dev_loss_tmo,
		   store_srp_rport_dev_loss_tmo);

static int srp_rport_set_state(struct srp_rport *rport,
			       enum srp_rport_state new_state)
{
	enum srp_rport_state old_state = rport->state;

	lockdep_assert_held(&rport->mutex);

	switch (new_state) {
	case SRP_RPORT_RUNNING:
		switch (old_state) {
		case SRP_RPORT_LOST:
			goto invalid;
		default:
			break;
		}
		break;
	case SRP_RPORT_BLOCKED:
		switch (old_state) {
		case SRP_RPORT_RUNNING:
			break;
		default:
			goto invalid;
		}
		break;
	case SRP_RPORT_FAIL_FAST:
		switch (old_state) {
		case SRP_RPORT_LOST:
			goto invalid;
		default:
			break;
		}
		break;
	case SRP_RPORT_LOST:
		break;
	}
	rport->state = new_state;
	return 0;

invalid:
	return -EINVAL;
}

/**
 * srp_reconnect_work() - reconnect and schedule a new attempt if necessary
 * @work: Work structure used for scheduling this operation.
 */
static void srp_reconnect_work(struct work_struct *work)
{
	struct srp_rport *rport = container_of(to_delayed_work(work),
					struct srp_rport, reconnect_work);
	struct Scsi_Host *shost = rport_to_shost(rport);
	int delay, res;

	res = srp_reconnect_rport(rport);
	if (res != 0) {
		shost_printk(KERN_ERR, shost,
			     "reconnect attempt %d failed (%d)\n",
			     ++rport->failed_reconnects, res);
		delay = rport->reconnect_delay *
			min(100, max(1, rport->failed_reconnects - 10));
		if (delay > 0)
			queue_delayed_work(system_long_wq,
					   &rport->reconnect_work, delay * HZ);
	}
}

static void __rport_fail_io_fast(struct srp_rport *rport)
{
	struct Scsi_Host *shost = rport_to_shost(rport);
	struct srp_internal *i;

	lockdep_assert_held(&rport->mutex);

	if (srp_rport_set_state(rport, SRP_RPORT_FAIL_FAST))
		return;
	scsi_target_unblock(rport->dev.parent, SDEV_TRANSPORT_OFFLINE);

	/* Involve the LLD if possible to terminate all I/O on the rport. */
	i = to_srp_internal(shost->transportt);
	if (i->f->terminate_rport_io)
		i->f->terminate_rport_io(rport);
}

/**
 * rport_fast_io_fail_timedout() - fast I/O failure timeout handler
 * @work: Work structure used for scheduling this operation.
 */
static void rport_fast_io_fail_timedout(struct work_struct *work)
{
	struct srp_rport *rport = container_of(to_delayed_work(work),
					struct srp_rport, fast_io_fail_work);
	struct Scsi_Host *shost = rport_to_shost(rport);

	pr_info("fast_io_fail_tmo expired for SRP %s / %s.\n",
		dev_name(&rport->dev), dev_name(&shost->shost_gendev));

	mutex_lock(&rport->mutex);
	if (rport->state == SRP_RPORT_BLOCKED)
		__rport_fail_io_fast(rport);
	mutex_unlock(&rport->mutex);
}

/**
 * rport_dev_loss_timedout() - device loss timeout handler
 * @work: Work structure used for scheduling this operation.
 */
static void rport_dev_loss_timedout(struct work_struct *work)
{
	struct srp_rport *rport = container_of(to_delayed_work(work),
					struct srp_rport, dev_loss_work);
	struct Scsi_Host *shost = rport_to_shost(rport);
	struct srp_internal *i = to_srp_internal(shost->transportt);

	pr_info("dev_loss_tmo expired for SRP %s / %s.\n",
		dev_name(&rport->dev), dev_name(&shost->shost_gendev));

	mutex_lock(&rport->mutex);
	WARN_ON(srp_rport_set_state(rport, SRP_RPORT_LOST) != 0);
	scsi_target_unblock(rport->dev.parent, SDEV_TRANSPORT_OFFLINE);
	mutex_unlock(&rport->mutex);

	i->f->rport_delete(rport);
}

static void __srp_start_tl_fail_timers(struct srp_rport *rport)
{
	struct Scsi_Host *shost = rport_to_shost(rport);
	int delay, fast_io_fail_tmo, dev_loss_tmo;

	lockdep_assert_held(&rport->mutex);

	delay = rport->reconnect_delay;
	fast_io_fail_tmo = rport->fast_io_fail_tmo;
	dev_loss_tmo = rport->dev_loss_tmo;
	pr_debug("%s current state: %d\n", dev_name(&shost->shost_gendev),
		 rport->state);

	if (rport->state == SRP_RPORT_LOST)
		return;
	if (delay > 0)
		queue_delayed_work(system_long_wq, &rport->reconnect_work,
				   1UL * delay * HZ);
	if ((fast_io_fail_tmo >= 0 || dev_loss_tmo >= 0) &&
	    srp_rport_set_state(rport, SRP_RPORT_BLOCKED) == 0) {
		pr_debug("%s new state: %d\n", dev_name(&shost->shost_gendev),
			 rport->state);
		scsi_target_block(&shost->shost_gendev);
		if (fast_io_fail_tmo >= 0)
			queue_delayed_work(system_long_wq,
					   &rport->fast_io_fail_work,
					   1UL * fast_io_fail_tmo * HZ);
		if (dev_loss_tmo >= 0)
			queue_delayed_work(system_long_wq,
					   &rport->dev_loss_work,
					   1UL * dev_loss_tmo * HZ);
	}
}

/**
 * srp_start_tl_fail_timers() - start the transport layer failure timers
 * @rport: SRP target port.
 *
 * Start the transport layer fast I/O failure and device loss timers. Do not
 * modify a timer that was already started.
 */
void srp_start_tl_fail_timers(struct srp_rport *rport)
{
	mutex_lock(&rport->mutex);
	__srp_start_tl_fail_timers(rport);
	mutex_unlock(&rport->mutex);
}
EXPORT_SYMBOL(srp_start_tl_fail_timers);

/**
 * scsi_request_fn_active() - number of kernel threads inside scsi_request_fn()
 * @shost: SCSI host for which to count the number of scsi_request_fn() callers.
 */
static int scsi_request_fn_active(struct Scsi_Host *shost)
{
	struct scsi_device *sdev;
	struct request_queue *q;
	int request_fn_active = 0;

	shost_for_each_device(sdev, shost) {
		q = sdev->request_queue;

		spin_lock_irq(q->queue_lock);
		request_fn_active += q->request_fn_active;
		spin_unlock_irq(q->queue_lock);
	}

	return request_fn_active;
}

/**
 * srp_reconnect_rport() - reconnect to an SRP target port
 * @rport: SRP target port.
 *
 * Blocks SCSI command queueing before invoking reconnect() such that
 * queuecommand() won't be invoked concurrently with reconnect() from outside
 * the SCSI EH. This is important since a reconnect() implementation may
 * reallocate resources needed by queuecommand().
 *
 * Notes:
 * - This function neither waits until outstanding requests have finished nor
 *   tries to abort these. It is the responsibility of the reconnect()
 *   function to finish outstanding commands before reconnecting to the target
 *   port.
 * - It is the responsibility of the caller to ensure that the resources
 *   reallocated by the reconnect() function won't be used while this function
 *   is in progress. One possible strategy is to invoke this function from
 *   the context of the SCSI EH thread only. Another possible strategy is to
 *   lock the rport mutex inside each SCSI LLD callback that can be invoked by
 *   the SCSI EH (the scsi_host_template.eh_*() functions and also the
 *   scsi_host_template.queuecommand() function).
 */
int srp_reconnect_rport(struct srp_rport *rport)
{
	struct Scsi_Host *shost = rport_to_shost(rport);
	struct srp_internal *i = to_srp_internal(shost->transportt);
	struct scsi_device *sdev;
	int res;

	pr_debug("SCSI host %s\n", dev_name(&shost->shost_gendev));

	res = mutex_lock_interruptible(&rport->mutex);
	if (res)
		goto out;
	scsi_target_block(&shost->shost_gendev);
	while (scsi_request_fn_active(shost))
		msleep(20);
	res = rport->state != SRP_RPORT_LOST ? i->f->reconnect(rport) : -ENODEV;
	pr_debug("%s (state %d): transport.reconnect() returned %d\n",
		 dev_name(&shost->shost_gendev), rport->state, res);
	if (res == 0) {
		cancel_delayed_work(&rport->fast_io_fail_work);
		cancel_delayed_work(&rport->dev_loss_work);

		rport->failed_reconnects = 0;
		srp_rport_set_state(rport, SRP_RPORT_RUNNING);
		scsi_target_unblock(&shost->shost_gendev, SDEV_RUNNING);
		/*
		 * If the SCSI error handler has offlined one or more devices,
		 * invoking scsi_target_unblock() won't change the state of
		 * these devices into running so do that explicitly.
		 */
		spin_lock_irq(shost->host_lock);
		__shost_for_each_device(sdev, shost)
			if (sdev->sdev_state == SDEV_OFFLINE)
				sdev->sdev_state = SDEV_RUNNING;
		spin_unlock_irq(shost->host_lock);
	} else if (rport->state == SRP_RPORT_RUNNING) {
		/*
		 * srp_reconnect_rport() has been invoked with fast_io_fail
		 * and dev_loss off. Mark the port as failed and start the TL
		 * failure timers if these had not yet been started.
		 */
		__rport_fail_io_fast(rport);
		scsi_target_unblock(&shost->shost_gendev,
				    SDEV_TRANSPORT_OFFLINE);
		__srp_start_tl_fail_timers(rport);
	} else if (rport->state != SRP_RPORT_BLOCKED) {
		scsi_target_unblock(&shost->shost_gendev,
				    SDEV_TRANSPORT_OFFLINE);
	}
	mutex_unlock(&rport->mutex);

out:
	return res;
}
EXPORT_SYMBOL(srp_reconnect_rport);

/**
 * srp_timed_out() - SRP transport intercept of the SCSI timeout EH
 * @scmd: SCSI command.
 *
 * If a timeout occurs while an rport is in the blocked state, ask the SCSI
 * EH to continue waiting (BLK_EH_RESET_TIMER). Otherwise let the SCSI core
 * handle the timeout (BLK_EH_NOT_HANDLED).
 *
 * Note: This function is called from soft-IRQ context and with the request
 * queue lock held.
 */
static enum blk_eh_timer_return srp_timed_out(struct scsi_cmnd *scmd)
{
	struct scsi_device *sdev = scmd->device;
	struct Scsi_Host *shost = sdev->host;
	struct srp_internal *i = to_srp_internal(shost->transportt);

	pr_debug("timeout for sdev %s\n", dev_name(&sdev->sdev_gendev));
	return i->f->reset_timer_if_blocked && scsi_device_blocked(sdev) ?
		BLK_EH_RESET_TIMER : BLK_EH_NOT_HANDLED;
}

static void srp_rport_release(struct device *dev)
{
	struct srp_rport *rport = dev_to_rport(dev);

	put_device(dev->parent);
	kfree(rport);
}

static int scsi_is_srp_rport(const struct device *dev)
{
	return dev->release == srp_rport_release;
}

static int srp_rport_match(struct attribute_container *cont,
			   struct device *dev)
{
	struct Scsi_Host *shost;
	struct srp_internal *i;

	if (!scsi_is_srp_rport(dev))
		return 0;

	shost = dev_to_shost(dev->parent);
	if (!shost->transportt)
		return 0;
	if (shost->transportt->host_attrs.ac.class != &srp_host_class.class)
		return 0;

	i = to_srp_internal(shost->transportt);
	return &i->rport_attr_cont.ac == cont;
}

static int srp_host_match(struct attribute_container *cont, struct device *dev)
{
	struct Scsi_Host *shost;
	struct srp_internal *i;

	if (!scsi_is_host_device(dev))
		return 0;

	shost = dev_to_shost(dev);
	if (!shost->transportt)
		return 0;
	if (shost->transportt->host_attrs.ac.class != &srp_host_class.class)
		return 0;

	i = to_srp_internal(shost->transportt);
	return &i->t.host_attrs.ac == cont;
}

/**
 * srp_rport_get() - increment rport reference count
 * @rport: SRP target port.
 */
void srp_rport_get(struct srp_rport *rport)
{
	get_device(&rport->dev);
}
EXPORT_SYMBOL(srp_rport_get);

/**
 * srp_rport_put() - decrement rport reference count
 * @rport: SRP target port.
 */
void srp_rport_put(struct srp_rport *rport)
{
	put_device(&rport->dev);
}
EXPORT_SYMBOL(srp_rport_put);

/**
 * srp_rport_add - add a SRP remote port to the device hierarchy
 * @shost:	scsi host the remote port is connected to.
 * @ids:	The port id for the remote port.
 *
 * Publishes a port to the rest of the system.
 */
struct srp_rport *srp_rport_add(struct Scsi_Host *shost,
				struct srp_rport_identifiers *ids)
{
	struct srp_rport *rport;
	struct device *parent = &shost->shost_gendev;
	struct srp_internal *i = to_srp_internal(shost->transportt);
	int id, ret;

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

	mutex_init(&rport->mutex);

	device_initialize(&rport->dev);

	rport->dev.parent = get_device(parent);
	rport->dev.release = srp_rport_release;

	memcpy(rport->port_id, ids->port_id, sizeof(rport->port_id));
	rport->roles = ids->roles;

	if (i->f->reconnect)
		rport->reconnect_delay = i->f->reconnect_delay ?
			*i->f->reconnect_delay : 10;
	INIT_DELAYED_WORK(&rport->reconnect_work, srp_reconnect_work);
	rport->fast_io_fail_tmo = i->f->fast_io_fail_tmo ?
		*i->f->fast_io_fail_tmo : 15;
	rport->dev_loss_tmo = i->f->dev_loss_tmo ? *i->f->dev_loss_tmo : 60;
	INIT_DELAYED_WORK(&rport->fast_io_fail_work,
			  rport_fast_io_fail_timedout);
	INIT_DELAYED_WORK(&rport->dev_loss_work, rport_dev_loss_timedout);

	id = atomic_inc_return(&to_srp_host_attrs(shost)->next_port_id);
	dev_set_name(&rport->dev, "port-%d:%d", shost->host_no, id);

	transport_setup_device(&rport->dev);

	ret = device_add(&rport->dev);
	if (ret) {
		transport_destroy_device(&rport->dev);
		put_device(&rport->dev);
		return ERR_PTR(ret);
	}

	transport_add_device(&rport->dev);
	transport_configure_device(&rport->dev);

	return rport;
}
EXPORT_SYMBOL_GPL(srp_rport_add);

/**
 * srp_rport_del  -  remove a SRP remote port
 * @rport:	SRP remote port to remove
 *
 * Removes the specified SRP remote port.
 */
void srp_rport_del(struct srp_rport *rport)
{
	struct device *dev = &rport->dev;

	transport_remove_device(dev);
	device_del(dev);
	transport_destroy_device(dev);

	put_device(dev);
}
EXPORT_SYMBOL_GPL(srp_rport_del);

static int do_srp_rport_del(struct device *dev, void *data)
{
	if (scsi_is_srp_rport(dev))
		srp_rport_del(dev_to_rport(dev));
	return 0;
}

/**
 * srp_remove_host  -  tear down a Scsi_Host's SRP data structures
 * @shost:	Scsi Host that is torn down
 *
 * Removes all SRP remote ports for a given Scsi_Host.
 * Must be called just before scsi_remove_host for SRP HBAs.
 */
void srp_remove_host(struct Scsi_Host *shost)
{
	device_for_each_child(&shost->shost_gendev, NULL, do_srp_rport_del);
}
EXPORT_SYMBOL_GPL(srp_remove_host);

/**
 * srp_stop_rport_timers - stop the transport layer recovery timers
 * @rport: SRP remote port for which to stop the timers.
 *
 * Must be called after srp_remove_host() and scsi_remove_host(). The caller
 * must hold a reference on the rport (rport->dev) and on the SCSI host
 * (rport->dev.parent).
 */
void srp_stop_rport_timers(struct srp_rport *rport)
{
	mutex_lock(&rport->mutex);
	if (rport->state == SRP_RPORT_BLOCKED)
		__rport_fail_io_fast(rport);
	srp_rport_set_state(rport, SRP_RPORT_LOST);
	mutex_unlock(&rport->mutex);

	cancel_delayed_work_sync(&rport->reconnect_work);
	cancel_delayed_work_sync(&rport->fast_io_fail_work);
	cancel_delayed_work_sync(&rport->dev_loss_work);
}
EXPORT_SYMBOL_GPL(srp_stop_rport_timers);

static int srp_tsk_mgmt_response(struct Scsi_Host *shost, u64 nexus, u64 tm_id,
				 int result)
{
	struct srp_internal *i = to_srp_internal(shost->transportt);
	return i->f->tsk_mgmt_response(shost, nexus, tm_id, result);
}

static int srp_it_nexus_response(struct Scsi_Host *shost, u64 nexus, int result)
{
	struct srp_internal *i = to_srp_internal(shost->transportt);
	return i->f->it_nexus_response(shost, nexus, result);
}

/**
 * srp_attach_transport  -  instantiate SRP transport template
 * @ft:		SRP transport class function template
 */
struct scsi_transport_template *
srp_attach_transport(struct srp_function_template *ft)
{
	int count;
	struct srp_internal *i;

	i = kzalloc(sizeof(*i), GFP_KERNEL);
	if (!i)
		return NULL;

	i->t.eh_timed_out = srp_timed_out;

	i->t.tsk_mgmt_response = srp_tsk_mgmt_response;
	i->t.it_nexus_response = srp_it_nexus_response;

	i->t.host_size = sizeof(struct srp_host_attrs);
	i->t.host_attrs.ac.attrs = &i->host_attrs[0];
	i->t.host_attrs.ac.class = &srp_host_class.class;
	i->t.host_attrs.ac.match = srp_host_match;
	i->host_attrs[0] = NULL;
	transport_container_register(&i->t.host_attrs);

	i->rport_attr_cont.ac.attrs = &i->rport_attrs[0];
	i->rport_attr_cont.ac.class = &srp_rport_class.class;
	i->rport_attr_cont.ac.match = srp_rport_match;

	count = 0;
	i->rport_attrs[count++] = &dev_attr_port_id;
	i->rport_attrs[count++] = &dev_attr_roles;
	if (ft->has_rport_state) {
		i->rport_attrs[count++] = &dev_attr_state;
		i->rport_attrs[count++] = &dev_attr_fast_io_fail_tmo;
		i->rport_attrs[count++] = &dev_attr_dev_loss_tmo;
	}
	if (ft->reconnect) {
		i->rport_attrs[count++] = &dev_attr_reconnect_delay;
		i->rport_attrs[count++] = &dev_attr_failed_reconnects;
	}
	if (ft->rport_delete)
		i->rport_attrs[count++] = &dev_attr_delete;
	i->rport_attrs[count++] = NULL;
	BUG_ON(count > ARRAY_SIZE(i->rport_attrs));

	transport_container_register(&i->rport_attr_cont);

	i->f = ft;

	return &i->t;
}
EXPORT_SYMBOL_GPL(srp_attach_transport);

/**
 * srp_release_transport  -  release SRP transport template instance
 * @t:		transport template instance
 */
void srp_release_transport(struct scsi_transport_template *t)
{
	struct srp_internal *i = to_srp_internal(t);

	transport_container_unregister(&i->t.host_attrs);
	transport_container_unregister(&i->rport_attr_cont);

	kfree(i);
}
EXPORT_SYMBOL_GPL(srp_release_transport);

static __init int srp_transport_init(void)
{
	int ret;

	ret = transport_class_register(&srp_host_class);
	if (ret)
		return ret;
	ret = transport_class_register(&srp_rport_class);
	if (ret)
		goto unregister_host_class;

	return 0;
unregister_host_class:
	transport_class_unregister(&srp_host_class);
	return ret;
}

static void __exit srp_transport_exit(void)
{
	transport_class_unregister(&srp_host_class);
	transport_class_unregister(&srp_rport_class);
}

MODULE_AUTHOR("FUJITA Tomonori");
MODULE_DESCRIPTION("SRP Transport Attributes");
MODULE_LICENSE("GPL");

module_init(srp_transport_init);
module_exit(srp_transport_exit);