aboutsummaryrefslogtreecommitdiff
path: root/drivers/s390/scsi/zfcp_aux.c
blob: 66d6c01fcf3e32ed9e720ad4a3f58733f6c4798b (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
/*
 * zfcp device driver
 *
 * Module interface and handling of zfcp data structures.
 *
 * Copyright IBM Corporation 2002, 2010
 */

/*
 * Driver authors:
 *            Martin Peschke (originator of the driver)
 *            Raimund Schroeder
 *            Aron Zeh
 *            Wolfgang Taphorn
 *            Stefan Bader
 *            Heiko Carstens (kernel 2.6 port of the driver)
 *            Andreas Herrmann
 *            Maxim Shchetynin
 *            Volker Sameske
 *            Ralph Wuerthner
 *            Michael Loehr
 *            Swen Schillig
 *            Christof Schmitt
 *            Martin Petermann
 *            Sven Schuetz
 */

#define KMSG_COMPONENT "zfcp"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/miscdevice.h>
#include <linux/seq_file.h>
#include "zfcp_ext.h"
#include "zfcp_fc.h"
#include "zfcp_reqlist.h"

#define ZFCP_BUS_ID_SIZE	20

MODULE_AUTHOR("IBM Deutschland Entwicklung GmbH - linux390@de.ibm.com");
MODULE_DESCRIPTION("FCP HBA driver");
MODULE_LICENSE("GPL");

static char *init_device;
module_param_named(device, init_device, charp, 0400);
MODULE_PARM_DESC(device, "specify initial device");

static struct kmem_cache *zfcp_cache_hw_align(const char *name,
					      unsigned long size)
{
	return kmem_cache_create(name, size, roundup_pow_of_two(size), 0, NULL);
}

static void __init zfcp_init_device_configure(char *busid, u64 wwpn, u64 lun)
{
	struct ccw_device *cdev;
	struct zfcp_adapter *adapter;
	struct zfcp_port *port;
	struct zfcp_unit *unit;

	cdev = get_ccwdev_by_busid(&zfcp_ccw_driver, busid);
	if (!cdev)
		return;

	if (ccw_device_set_online(cdev))
		goto out_ccw_device;

	adapter = zfcp_ccw_adapter_by_cdev(cdev);
	if (!adapter)
		goto out_ccw_device;

	port = zfcp_get_port_by_wwpn(adapter, wwpn);
	if (!port)
		goto out_port;

	unit = zfcp_unit_enqueue(port, lun);
	if (IS_ERR(unit))
		goto out_unit;

	zfcp_erp_unit_reopen(unit, 0, "auidc_1", NULL);
	zfcp_erp_wait(adapter);
	flush_work(&unit->scsi_work);

out_unit:
	put_device(&port->dev);
out_port:
	zfcp_ccw_adapter_put(adapter);
out_ccw_device:
	put_device(&cdev->dev);
	return;
}

static void __init zfcp_init_device_setup(char *devstr)
{
	char *token;
	char *str, *str_saved;
	char busid[ZFCP_BUS_ID_SIZE];
	u64 wwpn, lun;

	/* duplicate devstr and keep the original for sysfs presentation*/
	str_saved = kmalloc(strlen(devstr) + 1, GFP_KERNEL);
	str = str_saved;
	if (!str)
		return;

	strcpy(str, devstr);

	token = strsep(&str, ",");
	if (!token || strlen(token) >= ZFCP_BUS_ID_SIZE)
		goto err_out;
	strncpy(busid, token, ZFCP_BUS_ID_SIZE);

	token = strsep(&str, ",");
	if (!token || strict_strtoull(token, 0, (unsigned long long *) &wwpn))
		goto err_out;

	token = strsep(&str, ",");
	if (!token || strict_strtoull(token, 0, (unsigned long long *) &lun))
		goto err_out;

	kfree(str_saved);
	zfcp_init_device_configure(busid, wwpn, lun);
	return;

err_out:
	kfree(str_saved);
	pr_err("%s is not a valid SCSI device\n", devstr);
}

static int __init zfcp_module_init(void)
{
	int retval = -ENOMEM;

	zfcp_data.gpn_ft_cache = zfcp_cache_hw_align("zfcp_gpn",
					sizeof(struct zfcp_fc_gpn_ft_req));
	if (!zfcp_data.gpn_ft_cache)
		goto out;

	zfcp_data.qtcb_cache = zfcp_cache_hw_align("zfcp_qtcb",
					sizeof(struct fsf_qtcb));
	if (!zfcp_data.qtcb_cache)
		goto out_qtcb_cache;

	zfcp_data.sr_buffer_cache = zfcp_cache_hw_align("zfcp_sr",
					sizeof(struct fsf_status_read_buffer));
	if (!zfcp_data.sr_buffer_cache)
		goto out_sr_cache;

	zfcp_data.gid_pn_cache = zfcp_cache_hw_align("zfcp_gid",
					sizeof(struct zfcp_fc_gid_pn));
	if (!zfcp_data.gid_pn_cache)
		goto out_gid_cache;

	zfcp_data.adisc_cache = zfcp_cache_hw_align("zfcp_adisc",
					sizeof(struct zfcp_fc_els_adisc));
	if (!zfcp_data.adisc_cache)
		goto out_adisc_cache;

	zfcp_data.scsi_transport_template =
		fc_attach_transport(&zfcp_transport_functions);
	if (!zfcp_data.scsi_transport_template)
		goto out_transport;

	retval = misc_register(&zfcp_cfdc_misc);
	if (retval) {
		pr_err("Registering the misc device zfcp_cfdc failed\n");
		goto out_misc;
	}

	retval = ccw_driver_register(&zfcp_ccw_driver);
	if (retval) {
		pr_err("The zfcp device driver could not register with "
		       "the common I/O layer\n");
		goto out_ccw_register;
	}

	if (init_device)
		zfcp_init_device_setup(init_device);
	return 0;

out_ccw_register:
	misc_deregister(&zfcp_cfdc_misc);
out_misc:
	fc_release_transport(zfcp_data.scsi_transport_template);
out_transport:
	kmem_cache_destroy(zfcp_data.adisc_cache);
out_adisc_cache:
	kmem_cache_destroy(zfcp_data.gid_pn_cache);
out_gid_cache:
	kmem_cache_destroy(zfcp_data.sr_buffer_cache);
out_sr_cache:
	kmem_cache_destroy(zfcp_data.qtcb_cache);
out_qtcb_cache:
	kmem_cache_destroy(zfcp_data.gpn_ft_cache);
out:
	return retval;
}

module_init(zfcp_module_init);

static void __exit zfcp_module_exit(void)
{
	ccw_driver_unregister(&zfcp_ccw_driver);
	misc_deregister(&zfcp_cfdc_misc);
	fc_release_transport(zfcp_data.scsi_transport_template);
	kmem_cache_destroy(zfcp_data.adisc_cache);
	kmem_cache_destroy(zfcp_data.gid_pn_cache);
	kmem_cache_destroy(zfcp_data.sr_buffer_cache);
	kmem_cache_destroy(zfcp_data.qtcb_cache);
	kmem_cache_destroy(zfcp_data.gpn_ft_cache);
}

module_exit(zfcp_module_exit);

/**
 * zfcp_get_unit_by_lun - find unit in unit list of port by FCP LUN
 * @port: pointer to port to search for unit
 * @fcp_lun: FCP LUN to search for
 *
 * Returns: pointer to zfcp_unit or NULL
 */
struct zfcp_unit *zfcp_get_unit_by_lun(struct zfcp_port *port, u64 fcp_lun)
{
	unsigned long flags;
	struct zfcp_unit *unit;

	read_lock_irqsave(&port->unit_list_lock, flags);
	list_for_each_entry(unit, &port->unit_list, list)
		if (unit->fcp_lun == fcp_lun) {
			if (!get_device(&unit->dev))
				unit = NULL;
			read_unlock_irqrestore(&port->unit_list_lock, flags);
			return unit;
		}
	read_unlock_irqrestore(&port->unit_list_lock, flags);
	return NULL;
}

/**
 * zfcp_get_port_by_wwpn - find port in port list of adapter by wwpn
 * @adapter: pointer to adapter to search for port
 * @wwpn: wwpn to search for
 *
 * Returns: pointer to zfcp_port or NULL
 */
struct zfcp_port *zfcp_get_port_by_wwpn(struct zfcp_adapter *adapter,
					u64 wwpn)
{
	unsigned long flags;
	struct zfcp_port *port;

	read_lock_irqsave(&adapter->port_list_lock, flags);
	list_for_each_entry(port, &adapter->port_list, list)
		if (port->wwpn == wwpn) {
			if (!get_device(&port->dev))
				port = NULL;
			read_unlock_irqrestore(&adapter->port_list_lock, flags);
			return port;
		}
	read_unlock_irqrestore(&adapter->port_list_lock, flags);
	return NULL;
}

/**
 * zfcp_unit_release - dequeue unit
 * @dev: pointer to device
 *
 * waits until all work is done on unit and removes it then from the unit->list
 * of the associated port.
 */
static void zfcp_unit_release(struct device *dev)
{
	struct zfcp_unit *unit = container_of(dev, struct zfcp_unit, dev);

	put_device(&unit->port->dev);
	kfree(unit);
}

/**
 * zfcp_unit_enqueue - enqueue unit to unit list of a port.
 * @port: pointer to port where unit is added
 * @fcp_lun: FCP LUN of unit to be enqueued
 * Returns: pointer to enqueued unit on success, ERR_PTR on error
 *
 * Sets up some unit internal structures and creates sysfs entry.
 */
struct zfcp_unit *zfcp_unit_enqueue(struct zfcp_port *port, u64 fcp_lun)
{
	struct zfcp_unit *unit;
	int retval = -ENOMEM;

	get_device(&port->dev);

	unit = zfcp_get_unit_by_lun(port, fcp_lun);
	if (unit) {
		put_device(&unit->dev);
		retval = -EEXIST;
		goto err_out;
	}

	unit = kzalloc(sizeof(struct zfcp_unit), GFP_KERNEL);
	if (!unit)
		goto err_out;

	unit->port = port;
	unit->fcp_lun = fcp_lun;
	unit->dev.parent = &port->dev;
	unit->dev.release = zfcp_unit_release;

	if (dev_set_name(&unit->dev, "0x%016llx",
			 (unsigned long long) fcp_lun)) {
		kfree(unit);
		goto err_out;
	}
	retval = -EINVAL;

	INIT_WORK(&unit->scsi_work, zfcp_scsi_scan);

	spin_lock_init(&unit->latencies.lock);
	unit->latencies.write.channel.min = 0xFFFFFFFF;
	unit->latencies.write.fabric.min = 0xFFFFFFFF;
	unit->latencies.read.channel.min = 0xFFFFFFFF;
	unit->latencies.read.fabric.min = 0xFFFFFFFF;
	unit->latencies.cmd.channel.min = 0xFFFFFFFF;
	unit->latencies.cmd.fabric.min = 0xFFFFFFFF;

	if (device_register(&unit->dev)) {
		put_device(&unit->dev);
		goto err_out;
	}

	if (sysfs_create_group(&unit->dev.kobj, &zfcp_sysfs_unit_attrs))
		goto err_out_put;

	write_lock_irq(&port->unit_list_lock);
	list_add_tail(&unit->list, &port->unit_list);
	write_unlock_irq(&port->unit_list_lock);

	atomic_set_mask(ZFCP_STATUS_COMMON_RUNNING, &unit->status);

	return unit;

err_out_put:
	device_unregister(&unit->dev);
err_out:
	put_device(&port->dev);
	return ERR_PTR(retval);
}

static int zfcp_allocate_low_mem_buffers(struct zfcp_adapter *adapter)
{
	adapter->pool.erp_req =
		mempool_create_kmalloc_pool(1, sizeof(struct zfcp_fsf_req));
	if (!adapter->pool.erp_req)
		return -ENOMEM;

	adapter->pool.gid_pn_req =
		mempool_create_kmalloc_pool(1, sizeof(struct zfcp_fsf_req));
	if (!adapter->pool.gid_pn_req)
		return -ENOMEM;

	adapter->pool.scsi_req =
		mempool_create_kmalloc_pool(1, sizeof(struct zfcp_fsf_req));
	if (!adapter->pool.scsi_req)
		return -ENOMEM;

	adapter->pool.scsi_abort =
		mempool_create_kmalloc_pool(1, sizeof(struct zfcp_fsf_req));
	if (!adapter->pool.scsi_abort)
		return -ENOMEM;

	adapter->pool.status_read_req =
		mempool_create_kmalloc_pool(FSF_STATUS_READS_RECOM,
					    sizeof(struct zfcp_fsf_req));
	if (!adapter->pool.status_read_req)
		return -ENOMEM;

	adapter->pool.qtcb_pool =
		mempool_create_slab_pool(4, zfcp_data.qtcb_cache);
	if (!adapter->pool.qtcb_pool)
		return -ENOMEM;

	adapter->pool.status_read_data =
		mempool_create_slab_pool(FSF_STATUS_READS_RECOM,
					 zfcp_data.sr_buffer_cache);
	if (!adapter->pool.status_read_data)
		return -ENOMEM;

	adapter->pool.gid_pn =
		mempool_create_slab_pool(1, zfcp_data.gid_pn_cache);
	if (!adapter->pool.gid_pn)
		return -ENOMEM;

	return 0;
}

static void zfcp_free_low_mem_buffers(struct zfcp_adapter *adapter)
{
	if (adapter->pool.erp_req)
		mempool_destroy(adapter->pool.erp_req);
	if (adapter->pool.scsi_req)
		mempool_destroy(adapter->pool.scsi_req);
	if (adapter->pool.scsi_abort)
		mempool_destroy(adapter->pool.scsi_abort);
	if (adapter->pool.qtcb_pool)
		mempool_destroy(adapter->pool.qtcb_pool);
	if (adapter->pool.status_read_req)
		mempool_destroy(adapter->pool.status_read_req);
	if (adapter->pool.status_read_data)
		mempool_destroy(adapter->pool.status_read_data);
	if (adapter->pool.gid_pn)
		mempool_destroy(adapter->pool.gid_pn);
}

/**
 * zfcp_status_read_refill - refill the long running status_read_requests
 * @adapter: ptr to struct zfcp_adapter for which the buffers should be refilled
 *
 * Returns: 0 on success, 1 otherwise
 *
 * if there are 16 or more status_read requests missing an adapter_reopen
 * is triggered
 */
int zfcp_status_read_refill(struct zfcp_adapter *adapter)
{
	while (atomic_read(&adapter->stat_miss) > 0)
		if (zfcp_fsf_status_read(adapter->qdio)) {
			if (atomic_read(&adapter->stat_miss) >= 16) {
				zfcp_erp_adapter_reopen(adapter, 0, "axsref1",
							NULL);
				return 1;
			}
			break;
		} else
			atomic_dec(&adapter->stat_miss);
	return 0;
}

static void _zfcp_status_read_scheduler(struct work_struct *work)
{
	zfcp_status_read_refill(container_of(work, struct zfcp_adapter,
					     stat_work));
}

static void zfcp_print_sl(struct seq_file *m, struct service_level *sl)
{
	struct zfcp_adapter *adapter =
		container_of(sl, struct zfcp_adapter, service_level);

	seq_printf(m, "zfcp: %s microcode level %x\n",
		   dev_name(&adapter->ccw_device->dev),
		   adapter->fsf_lic_version);
}

static int zfcp_setup_adapter_work_queue(struct zfcp_adapter *adapter)
{
	char name[TASK_COMM_LEN];

	snprintf(name, sizeof(name), "zfcp_q_%s",
		 dev_name(&adapter->ccw_device->dev));
	adapter->work_queue = create_singlethread_workqueue(name);

	if (adapter->work_queue)
		return 0;
	return -ENOMEM;
}

static void zfcp_destroy_adapter_work_queue(struct zfcp_adapter *adapter)
{
	if (adapter->work_queue)
		destroy_workqueue(adapter->work_queue);
	adapter->work_queue = NULL;

}

/**
 * zfcp_adapter_enqueue - enqueue a new adapter to the list
 * @ccw_device: pointer to the struct cc_device
 *
 * Returns:	struct zfcp_adapter*
 * Enqueues an adapter at the end of the adapter list in the driver data.
 * All adapter internal structures are set up.
 * Proc-fs entries are also created.
 */
struct zfcp_adapter *zfcp_adapter_enqueue(struct ccw_device *ccw_device)
{
	struct zfcp_adapter *adapter;

	if (!get_device(&ccw_device->dev))
		return ERR_PTR(-ENODEV);

	adapter = kzalloc(sizeof(struct zfcp_adapter), GFP_KERNEL);
	if (!adapter) {
		put_device(&ccw_device->dev);
		return ERR_PTR(-ENOMEM);
	}

	kref_init(&adapter->ref);

	ccw_device->handler = NULL;
	adapter->ccw_device = ccw_device;

	INIT_WORK(&adapter->stat_work, _zfcp_status_read_scheduler);
	INIT_WORK(&adapter->scan_work, zfcp_fc_scan_ports);

	if (zfcp_qdio_setup(adapter))
		goto failed;

	if (zfcp_allocate_low_mem_buffers(adapter))
		goto failed;

	adapter->req_list = zfcp_reqlist_alloc();
	if (!adapter->req_list)
		goto failed;

	if (zfcp_dbf_adapter_register(adapter))
		goto failed;

	if (zfcp_setup_adapter_work_queue(adapter))
		goto failed;

	if (zfcp_fc_gs_setup(adapter))
		goto failed;

	rwlock_init(&adapter->port_list_lock);
	INIT_LIST_HEAD(&adapter->port_list);

	init_waitqueue_head(&adapter->erp_ready_wq);
	init_waitqueue_head(&adapter->erp_done_wqh);

	INIT_LIST_HEAD(&adapter->erp_ready_head);
	INIT_LIST_HEAD(&adapter->erp_running_head);

	rwlock_init(&adapter->erp_lock);
	rwlock_init(&adapter->abort_lock);

	if (zfcp_erp_thread_setup(adapter))
		goto failed;

	adapter->service_level.seq_print = zfcp_print_sl;

	dev_set_drvdata(&ccw_device->dev, adapter);

	if (sysfs_create_group(&ccw_device->dev.kobj,
			       &zfcp_sysfs_adapter_attrs))
		goto failed;

	if (!zfcp_adapter_scsi_register(adapter))
		return adapter;

failed:
	zfcp_adapter_unregister(adapter);
	return ERR_PTR(-ENOMEM);
}

void zfcp_adapter_unregister(struct zfcp_adapter *adapter)
{
	struct ccw_device *cdev = adapter->ccw_device;

	cancel_work_sync(&adapter->scan_work);
	cancel_work_sync(&adapter->stat_work);
	zfcp_destroy_adapter_work_queue(adapter);

	zfcp_fc_wka_ports_force_offline(adapter->gs);
	zfcp_adapter_scsi_unregister(adapter);
	sysfs_remove_group(&cdev->dev.kobj, &zfcp_sysfs_adapter_attrs);

	zfcp_erp_thread_kill(adapter);
	zfcp_dbf_adapter_unregister(adapter->dbf);
	zfcp_qdio_destroy(adapter->qdio);

	zfcp_ccw_adapter_put(adapter); /* final put to release */
}

/**
 * zfcp_adapter_release - remove the adapter from the resource list
 * @ref: pointer to struct kref
 * locks:	adapter list write lock is assumed to be held by caller
 */
void zfcp_adapter_release(struct kref *ref)
{
	struct zfcp_adapter *adapter = container_of(ref, struct zfcp_adapter,
						    ref);
	struct ccw_device *cdev = adapter->ccw_device;

	dev_set_drvdata(&adapter->ccw_device->dev, NULL);
	zfcp_fc_gs_destroy(adapter);
	zfcp_free_low_mem_buffers(adapter);
	kfree(adapter->req_list);
	kfree(adapter->fc_stats);
	kfree(adapter->stats_reset_data);
	kfree(adapter);
	put_device(&cdev->dev);
}

/**
 * zfcp_device_unregister - remove port, unit from system
 * @dev: reference to device which is to be removed
 * @grp: related reference to attribute group
 *
 * Helper function to unregister port, unit from system
 */
void zfcp_device_unregister(struct device *dev,
			    const struct attribute_group *grp)
{
	sysfs_remove_group(&dev->kobj, grp);
	device_unregister(dev);
}

static void zfcp_port_release(struct device *dev)
{
	struct zfcp_port *port = container_of(dev, struct zfcp_port, dev);

	zfcp_ccw_adapter_put(port->adapter);
	kfree(port);
}

/**
 * zfcp_port_enqueue - enqueue port to port list of adapter
 * @adapter: adapter where remote port is added
 * @wwpn: WWPN of the remote port to be enqueued
 * @status: initial status for the port
 * @d_id: destination id of the remote port to be enqueued
 * Returns: pointer to enqueued port on success, ERR_PTR on error
 *
 * All port internal structures are set up and the sysfs entry is generated.
 * d_id is used to enqueue ports with a well known address like the Directory
 * Service for nameserver lookup.
 */
struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,
				     u32 status, u32 d_id)
{
	struct zfcp_port *port;
	int retval = -ENOMEM;

	kref_get(&adapter->ref);

	port = zfcp_get_port_by_wwpn(adapter, wwpn);
	if (port) {
		put_device(&port->dev);
		retval = -EEXIST;
		goto err_out;
	}

	port = kzalloc(sizeof(struct zfcp_port), GFP_KERNEL);
	if (!port)
		goto err_out;

	rwlock_init(&port->unit_list_lock);
	INIT_LIST_HEAD(&port->unit_list);

	INIT_WORK(&port->gid_pn_work, zfcp_fc_port_did_lookup);
	INIT_WORK(&port->test_link_work, zfcp_fc_link_test_work);
	INIT_WORK(&port->rport_work, zfcp_scsi_rport_work);

	port->adapter = adapter;
	port->d_id = d_id;
	port->wwpn = wwpn;
	port->rport_task = RPORT_NONE;
	port->dev.parent = &adapter->ccw_device->dev;
	port->dev.release = zfcp_port_release;

	if (dev_set_name(&port->dev, "0x%016llx", (unsigned long long)wwpn)) {
		kfree(port);
		goto err_out;
	}
	retval = -EINVAL;

	if (device_register(&port->dev)) {
		put_device(&port->dev);
		goto err_out;
	}

	if (sysfs_create_group(&port->dev.kobj,
			       &zfcp_sysfs_port_attrs))
		goto err_out_put;

	write_lock_irq(&adapter->port_list_lock);
	list_add_tail(&port->list, &adapter->port_list);
	write_unlock_irq(&adapter->port_list_lock);

	atomic_set_mask(status | ZFCP_STATUS_COMMON_RUNNING, &port->status);

	return port;

err_out_put:
	device_unregister(&port->dev);
err_out:
	zfcp_ccw_adapter_put(adapter);
	return ERR_PTR(retval);
}

/**
 * zfcp_sg_free_table - free memory used by scatterlists
 * @sg: pointer to scatterlist
 * @count: number of scatterlist which are to be free'ed
 * the scatterlist are expected to reference pages always
 */
void zfcp_sg_free_table(struct scatterlist *sg, int count)
{
	int i;

	for (i = 0; i < count; i++, sg++)
		if (sg)
			free_page((unsigned long) sg_virt(sg));
		else
			break;
}

/**
 * zfcp_sg_setup_table - init scatterlist and allocate, assign buffers
 * @sg: pointer to struct scatterlist
 * @count: number of scatterlists which should be assigned with buffers
 * of size page
 *
 * Returns: 0 on success, -ENOMEM otherwise
 */
int zfcp_sg_setup_table(struct scatterlist *sg, int count)
{
	void *addr;
	int i;

	sg_init_table(sg, count);
	for (i = 0; i < count; i++, sg++) {
		addr = (void *) get_zeroed_page(GFP_KERNEL);
		if (!addr) {
			zfcp_sg_free_table(sg, i);
			return -ENOMEM;
		}
		sg_set_buf(sg, addr, PAGE_SIZE);
	}
	return 0;
}