xref: /openbmc/linux/drivers/scsi/scsi_scan.c (revision 6aa7de05)
1 /*
2  * scsi_scan.c
3  *
4  * Copyright (C) 2000 Eric Youngdale,
5  * Copyright (C) 2002 Patrick Mansfield
6  *
7  * The general scanning/probing algorithm is as follows, exceptions are
8  * made to it depending on device specific flags, compilation options, and
9  * global variable (boot or module load time) settings.
10  *
11  * A specific LUN is scanned via an INQUIRY command; if the LUN has a
12  * device attached, a scsi_device is allocated and setup for it.
13  *
14  * For every id of every channel on the given host:
15  *
16  * 	Scan LUN 0; if the target responds to LUN 0 (even if there is no
17  * 	device or storage attached to LUN 0):
18  *
19  * 		If LUN 0 has a device attached, allocate and setup a
20  * 		scsi_device for it.
21  *
22  * 		If target is SCSI-3 or up, issue a REPORT LUN, and scan
23  * 		all of the LUNs returned by the REPORT LUN; else,
24  * 		sequentially scan LUNs up until some maximum is reached,
25  * 		or a LUN is seen that cannot have a device attached to it.
26  */
27 
28 #include <linux/module.h>
29 #include <linux/moduleparam.h>
30 #include <linux/init.h>
31 #include <linux/blkdev.h>
32 #include <linux/delay.h>
33 #include <linux/kthread.h>
34 #include <linux/spinlock.h>
35 #include <linux/async.h>
36 #include <linux/slab.h>
37 #include <asm/unaligned.h>
38 
39 #include <scsi/scsi.h>
40 #include <scsi/scsi_cmnd.h>
41 #include <scsi/scsi_device.h>
42 #include <scsi/scsi_driver.h>
43 #include <scsi/scsi_devinfo.h>
44 #include <scsi/scsi_host.h>
45 #include <scsi/scsi_transport.h>
46 #include <scsi/scsi_dh.h>
47 #include <scsi/scsi_eh.h>
48 
49 #include "scsi_priv.h"
50 #include "scsi_logging.h"
51 
52 #define ALLOC_FAILURE_MSG	KERN_ERR "%s: Allocation failure during" \
53 	" SCSI scanning, some SCSI devices might not be configured\n"
54 
55 /*
56  * Default timeout
57  */
58 #define SCSI_TIMEOUT (2*HZ)
59 #define SCSI_REPORT_LUNS_TIMEOUT (30*HZ)
60 
61 /*
62  * Prefix values for the SCSI id's (stored in sysfs name field)
63  */
64 #define SCSI_UID_SER_NUM 'S'
65 #define SCSI_UID_UNKNOWN 'Z'
66 
67 /*
68  * Return values of some of the scanning functions.
69  *
70  * SCSI_SCAN_NO_RESPONSE: no valid response received from the target, this
71  * includes allocation or general failures preventing IO from being sent.
72  *
73  * SCSI_SCAN_TARGET_PRESENT: target responded, but no device is available
74  * on the given LUN.
75  *
76  * SCSI_SCAN_LUN_PRESENT: target responded, and a device is available on a
77  * given LUN.
78  */
79 #define SCSI_SCAN_NO_RESPONSE		0
80 #define SCSI_SCAN_TARGET_PRESENT	1
81 #define SCSI_SCAN_LUN_PRESENT		2
82 
83 static const char *scsi_null_device_strs = "nullnullnullnull";
84 
85 #define MAX_SCSI_LUNS	512
86 
87 static u64 max_scsi_luns = MAX_SCSI_LUNS;
88 
89 module_param_named(max_luns, max_scsi_luns, ullong, S_IRUGO|S_IWUSR);
90 MODULE_PARM_DESC(max_luns,
91 		 "last scsi LUN (should be between 1 and 2^64-1)");
92 
93 #ifdef CONFIG_SCSI_SCAN_ASYNC
94 #define SCSI_SCAN_TYPE_DEFAULT "async"
95 #else
96 #define SCSI_SCAN_TYPE_DEFAULT "sync"
97 #endif
98 
99 char scsi_scan_type[7] = SCSI_SCAN_TYPE_DEFAULT;
100 
101 module_param_string(scan, scsi_scan_type, sizeof(scsi_scan_type),
102 		    S_IRUGO|S_IWUSR);
103 MODULE_PARM_DESC(scan, "sync, async, manual, or none. "
104 		 "Setting to 'manual' disables automatic scanning, but allows "
105 		 "for manual device scan via the 'scan' sysfs attribute.");
106 
107 static unsigned int scsi_inq_timeout = SCSI_TIMEOUT/HZ + 18;
108 
109 module_param_named(inq_timeout, scsi_inq_timeout, uint, S_IRUGO|S_IWUSR);
110 MODULE_PARM_DESC(inq_timeout,
111 		 "Timeout (in seconds) waiting for devices to answer INQUIRY."
112 		 " Default is 20. Some devices may need more; most need less.");
113 
114 /* This lock protects only this list */
115 static DEFINE_SPINLOCK(async_scan_lock);
116 static LIST_HEAD(scanning_hosts);
117 
118 struct async_scan_data {
119 	struct list_head list;
120 	struct Scsi_Host *shost;
121 	struct completion prev_finished;
122 };
123 
124 /**
125  * scsi_complete_async_scans - Wait for asynchronous scans to complete
126  *
127  * When this function returns, any host which started scanning before
128  * this function was called will have finished its scan.  Hosts which
129  * started scanning after this function was called may or may not have
130  * finished.
131  */
132 int scsi_complete_async_scans(void)
133 {
134 	struct async_scan_data *data;
135 
136 	do {
137 		if (list_empty(&scanning_hosts))
138 			return 0;
139 		/* If we can't get memory immediately, that's OK.  Just
140 		 * sleep a little.  Even if we never get memory, the async
141 		 * scans will finish eventually.
142 		 */
143 		data = kmalloc(sizeof(*data), GFP_KERNEL);
144 		if (!data)
145 			msleep(1);
146 	} while (!data);
147 
148 	data->shost = NULL;
149 	init_completion(&data->prev_finished);
150 
151 	spin_lock(&async_scan_lock);
152 	/* Check that there's still somebody else on the list */
153 	if (list_empty(&scanning_hosts))
154 		goto done;
155 	list_add_tail(&data->list, &scanning_hosts);
156 	spin_unlock(&async_scan_lock);
157 
158 	printk(KERN_INFO "scsi: waiting for bus probes to complete ...\n");
159 	wait_for_completion(&data->prev_finished);
160 
161 	spin_lock(&async_scan_lock);
162 	list_del(&data->list);
163 	if (!list_empty(&scanning_hosts)) {
164 		struct async_scan_data *next = list_entry(scanning_hosts.next,
165 				struct async_scan_data, list);
166 		complete(&next->prev_finished);
167 	}
168  done:
169 	spin_unlock(&async_scan_lock);
170 
171 	kfree(data);
172 	return 0;
173 }
174 
175 /**
176  * scsi_unlock_floptical - unlock device via a special MODE SENSE command
177  * @sdev:	scsi device to send command to
178  * @result:	area to store the result of the MODE SENSE
179  *
180  * Description:
181  *     Send a vendor specific MODE SENSE (not a MODE SELECT) command.
182  *     Called for BLIST_KEY devices.
183  **/
184 static void scsi_unlock_floptical(struct scsi_device *sdev,
185 				  unsigned char *result)
186 {
187 	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
188 
189 	sdev_printk(KERN_NOTICE, sdev, "unlocking floptical drive\n");
190 	scsi_cmd[0] = MODE_SENSE;
191 	scsi_cmd[1] = 0;
192 	scsi_cmd[2] = 0x2e;
193 	scsi_cmd[3] = 0;
194 	scsi_cmd[4] = 0x2a;     /* size */
195 	scsi_cmd[5] = 0;
196 	scsi_execute_req(sdev, scsi_cmd, DMA_FROM_DEVICE, result, 0x2a, NULL,
197 			 SCSI_TIMEOUT, 3, NULL);
198 }
199 
200 /**
201  * scsi_alloc_sdev - allocate and setup a scsi_Device
202  * @starget: which target to allocate a &scsi_device for
203  * @lun: which lun
204  * @hostdata: usually NULL and set by ->slave_alloc instead
205  *
206  * Description:
207  *     Allocate, initialize for io, and return a pointer to a scsi_Device.
208  *     Stores the @shost, @channel, @id, and @lun in the scsi_Device, and
209  *     adds scsi_Device to the appropriate list.
210  *
211  * Return value:
212  *     scsi_Device pointer, or NULL on failure.
213  **/
214 static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
215 					   u64 lun, void *hostdata)
216 {
217 	struct scsi_device *sdev;
218 	int display_failure_msg = 1, ret;
219 	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
220 
221 	sdev = kzalloc(sizeof(*sdev) + shost->transportt->device_size,
222 		       GFP_ATOMIC);
223 	if (!sdev)
224 		goto out;
225 
226 	sdev->vendor = scsi_null_device_strs;
227 	sdev->model = scsi_null_device_strs;
228 	sdev->rev = scsi_null_device_strs;
229 	sdev->host = shost;
230 	sdev->queue_ramp_up_period = SCSI_DEFAULT_RAMP_UP_PERIOD;
231 	sdev->id = starget->id;
232 	sdev->lun = lun;
233 	sdev->channel = starget->channel;
234 	mutex_init(&sdev->state_mutex);
235 	sdev->sdev_state = SDEV_CREATED;
236 	INIT_LIST_HEAD(&sdev->siblings);
237 	INIT_LIST_HEAD(&sdev->same_target_siblings);
238 	INIT_LIST_HEAD(&sdev->cmd_list);
239 	INIT_LIST_HEAD(&sdev->starved_entry);
240 	INIT_LIST_HEAD(&sdev->event_list);
241 	spin_lock_init(&sdev->list_lock);
242 	mutex_init(&sdev->inquiry_mutex);
243 	INIT_WORK(&sdev->event_work, scsi_evt_thread);
244 	INIT_WORK(&sdev->requeue_work, scsi_requeue_run_queue);
245 
246 	sdev->sdev_gendev.parent = get_device(&starget->dev);
247 	sdev->sdev_target = starget;
248 
249 	/* usually NULL and set by ->slave_alloc instead */
250 	sdev->hostdata = hostdata;
251 
252 	/* if the device needs this changing, it may do so in the
253 	 * slave_configure function */
254 	sdev->max_device_blocked = SCSI_DEFAULT_DEVICE_BLOCKED;
255 
256 	/*
257 	 * Some low level driver could use device->type
258 	 */
259 	sdev->type = -1;
260 
261 	/*
262 	 * Assume that the device will have handshaking problems,
263 	 * and then fix this field later if it turns out it
264 	 * doesn't
265 	 */
266 	sdev->borken = 1;
267 
268 	if (shost_use_blk_mq(shost))
269 		sdev->request_queue = scsi_mq_alloc_queue(sdev);
270 	else
271 		sdev->request_queue = scsi_old_alloc_queue(sdev);
272 	if (!sdev->request_queue) {
273 		/* release fn is set up in scsi_sysfs_device_initialise, so
274 		 * have to free and put manually here */
275 		put_device(&starget->dev);
276 		kfree(sdev);
277 		goto out;
278 	}
279 	WARN_ON_ONCE(!blk_get_queue(sdev->request_queue));
280 	sdev->request_queue->queuedata = sdev;
281 
282 	if (!shost_use_blk_mq(sdev->host)) {
283 		blk_queue_init_tags(sdev->request_queue,
284 				    sdev->host->cmd_per_lun, shost->bqt,
285 				    shost->hostt->tag_alloc_policy);
286 	}
287 	scsi_change_queue_depth(sdev, sdev->host->cmd_per_lun ?
288 					sdev->host->cmd_per_lun : 1);
289 
290 	scsi_sysfs_device_initialize(sdev);
291 
292 	if (shost->hostt->slave_alloc) {
293 		ret = shost->hostt->slave_alloc(sdev);
294 		if (ret) {
295 			/*
296 			 * if LLDD reports slave not present, don't clutter
297 			 * console with alloc failure messages
298 			 */
299 			if (ret == -ENXIO)
300 				display_failure_msg = 0;
301 			goto out_device_destroy;
302 		}
303 	}
304 
305 	return sdev;
306 
307 out_device_destroy:
308 	__scsi_remove_device(sdev);
309 out:
310 	if (display_failure_msg)
311 		printk(ALLOC_FAILURE_MSG, __func__);
312 	return NULL;
313 }
314 
315 static void scsi_target_destroy(struct scsi_target *starget)
316 {
317 	struct device *dev = &starget->dev;
318 	struct Scsi_Host *shost = dev_to_shost(dev->parent);
319 	unsigned long flags;
320 
321 	BUG_ON(starget->state == STARGET_DEL);
322 	starget->state = STARGET_DEL;
323 	transport_destroy_device(dev);
324 	spin_lock_irqsave(shost->host_lock, flags);
325 	if (shost->hostt->target_destroy)
326 		shost->hostt->target_destroy(starget);
327 	list_del_init(&starget->siblings);
328 	spin_unlock_irqrestore(shost->host_lock, flags);
329 	put_device(dev);
330 }
331 
332 static void scsi_target_dev_release(struct device *dev)
333 {
334 	struct device *parent = dev->parent;
335 	struct scsi_target *starget = to_scsi_target(dev);
336 
337 	kfree(starget);
338 	put_device(parent);
339 }
340 
341 static struct device_type scsi_target_type = {
342 	.name =		"scsi_target",
343 	.release =	scsi_target_dev_release,
344 };
345 
346 int scsi_is_target_device(const struct device *dev)
347 {
348 	return dev->type == &scsi_target_type;
349 }
350 EXPORT_SYMBOL(scsi_is_target_device);
351 
352 static struct scsi_target *__scsi_find_target(struct device *parent,
353 					      int channel, uint id)
354 {
355 	struct scsi_target *starget, *found_starget = NULL;
356 	struct Scsi_Host *shost = dev_to_shost(parent);
357 	/*
358 	 * Search for an existing target for this sdev.
359 	 */
360 	list_for_each_entry(starget, &shost->__targets, siblings) {
361 		if (starget->id == id &&
362 		    starget->channel == channel) {
363 			found_starget = starget;
364 			break;
365 		}
366 	}
367 	if (found_starget)
368 		get_device(&found_starget->dev);
369 
370 	return found_starget;
371 }
372 
373 /**
374  * scsi_target_reap_ref_release - remove target from visibility
375  * @kref: the reap_ref in the target being released
376  *
377  * Called on last put of reap_ref, which is the indication that no device
378  * under this target is visible anymore, so render the target invisible in
379  * sysfs.  Note: we have to be in user context here because the target reaps
380  * should be done in places where the scsi device visibility is being removed.
381  */
382 static void scsi_target_reap_ref_release(struct kref *kref)
383 {
384 	struct scsi_target *starget
385 		= container_of(kref, struct scsi_target, reap_ref);
386 
387 	/*
388 	 * if we get here and the target is still in a CREATED state that
389 	 * means it was allocated but never made visible (because a scan
390 	 * turned up no LUNs), so don't call device_del() on it.
391 	 */
392 	if ((starget->state != STARGET_CREATED) &&
393 	    (starget->state != STARGET_CREATED_REMOVE)) {
394 		transport_remove_device(&starget->dev);
395 		device_del(&starget->dev);
396 	}
397 	scsi_target_destroy(starget);
398 }
399 
400 static void scsi_target_reap_ref_put(struct scsi_target *starget)
401 {
402 	kref_put(&starget->reap_ref, scsi_target_reap_ref_release);
403 }
404 
405 /**
406  * scsi_alloc_target - allocate a new or find an existing target
407  * @parent:	parent of the target (need not be a scsi host)
408  * @channel:	target channel number (zero if no channels)
409  * @id:		target id number
410  *
411  * Return an existing target if one exists, provided it hasn't already
412  * gone into STARGET_DEL state, otherwise allocate a new target.
413  *
414  * The target is returned with an incremented reference, so the caller
415  * is responsible for both reaping and doing a last put
416  */
417 static struct scsi_target *scsi_alloc_target(struct device *parent,
418 					     int channel, uint id)
419 {
420 	struct Scsi_Host *shost = dev_to_shost(parent);
421 	struct device *dev = NULL;
422 	unsigned long flags;
423 	const int size = sizeof(struct scsi_target)
424 		+ shost->transportt->target_size;
425 	struct scsi_target *starget;
426 	struct scsi_target *found_target;
427 	int error, ref_got;
428 
429 	starget = kzalloc(size, GFP_KERNEL);
430 	if (!starget) {
431 		printk(KERN_ERR "%s: allocation failure\n", __func__);
432 		return NULL;
433 	}
434 	dev = &starget->dev;
435 	device_initialize(dev);
436 	kref_init(&starget->reap_ref);
437 	dev->parent = get_device(parent);
438 	dev_set_name(dev, "target%d:%d:%d", shost->host_no, channel, id);
439 	dev->bus = &scsi_bus_type;
440 	dev->type = &scsi_target_type;
441 	starget->id = id;
442 	starget->channel = channel;
443 	starget->can_queue = 0;
444 	INIT_LIST_HEAD(&starget->siblings);
445 	INIT_LIST_HEAD(&starget->devices);
446 	starget->state = STARGET_CREATED;
447 	starget->scsi_level = SCSI_2;
448 	starget->max_target_blocked = SCSI_DEFAULT_TARGET_BLOCKED;
449  retry:
450 	spin_lock_irqsave(shost->host_lock, flags);
451 
452 	found_target = __scsi_find_target(parent, channel, id);
453 	if (found_target)
454 		goto found;
455 
456 	list_add_tail(&starget->siblings, &shost->__targets);
457 	spin_unlock_irqrestore(shost->host_lock, flags);
458 	/* allocate and add */
459 	transport_setup_device(dev);
460 	if (shost->hostt->target_alloc) {
461 		error = shost->hostt->target_alloc(starget);
462 
463 		if(error) {
464 			dev_printk(KERN_ERR, dev, "target allocation failed, error %d\n", error);
465 			/* don't want scsi_target_reap to do the final
466 			 * put because it will be under the host lock */
467 			scsi_target_destroy(starget);
468 			return NULL;
469 		}
470 	}
471 	get_device(dev);
472 
473 	return starget;
474 
475  found:
476 	/*
477 	 * release routine already fired if kref is zero, so if we can still
478 	 * take the reference, the target must be alive.  If we can't, it must
479 	 * be dying and we need to wait for a new target
480 	 */
481 	ref_got = kref_get_unless_zero(&found_target->reap_ref);
482 
483 	spin_unlock_irqrestore(shost->host_lock, flags);
484 	if (ref_got) {
485 		put_device(dev);
486 		return found_target;
487 	}
488 	/*
489 	 * Unfortunately, we found a dying target; need to wait until it's
490 	 * dead before we can get a new one.  There is an anomaly here.  We
491 	 * *should* call scsi_target_reap() to balance the kref_get() of the
492 	 * reap_ref above.  However, since the target being released, it's
493 	 * already invisible and the reap_ref is irrelevant.  If we call
494 	 * scsi_target_reap() we might spuriously do another device_del() on
495 	 * an already invisible target.
496 	 */
497 	put_device(&found_target->dev);
498 	/*
499 	 * length of time is irrelevant here, we just want to yield the CPU
500 	 * for a tick to avoid busy waiting for the target to die.
501 	 */
502 	msleep(1);
503 	goto retry;
504 }
505 
506 /**
507  * scsi_target_reap - check to see if target is in use and destroy if not
508  * @starget: target to be checked
509  *
510  * This is used after removing a LUN or doing a last put of the target
511  * it checks atomically that nothing is using the target and removes
512  * it if so.
513  */
514 void scsi_target_reap(struct scsi_target *starget)
515 {
516 	/*
517 	 * serious problem if this triggers: STARGET_DEL is only set in the if
518 	 * the reap_ref drops to zero, so we're trying to do another final put
519 	 * on an already released kref
520 	 */
521 	BUG_ON(starget->state == STARGET_DEL);
522 	scsi_target_reap_ref_put(starget);
523 }
524 
525 /**
526  * scsi_sanitize_inquiry_string - remove non-graphical chars from an
527  *                                INQUIRY result string
528  * @s: INQUIRY result string to sanitize
529  * @len: length of the string
530  *
531  * Description:
532  *	The SCSI spec says that INQUIRY vendor, product, and revision
533  *	strings must consist entirely of graphic ASCII characters,
534  *	padded on the right with spaces.  Since not all devices obey
535  *	this rule, we will replace non-graphic or non-ASCII characters
536  *	with spaces.  Exception: a NUL character is interpreted as a
537  *	string terminator, so all the following characters are set to
538  *	spaces.
539  **/
540 void scsi_sanitize_inquiry_string(unsigned char *s, int len)
541 {
542 	int terminated = 0;
543 
544 	for (; len > 0; (--len, ++s)) {
545 		if (*s == 0)
546 			terminated = 1;
547 		if (terminated || *s < 0x20 || *s > 0x7e)
548 			*s = ' ';
549 	}
550 }
551 EXPORT_SYMBOL(scsi_sanitize_inquiry_string);
552 
553 /**
554  * scsi_probe_lun - probe a single LUN using a SCSI INQUIRY
555  * @sdev:	scsi_device to probe
556  * @inq_result:	area to store the INQUIRY result
557  * @result_len: len of inq_result
558  * @bflags:	store any bflags found here
559  *
560  * Description:
561  *     Probe the lun associated with @req using a standard SCSI INQUIRY;
562  *
563  *     If the INQUIRY is successful, zero is returned and the
564  *     INQUIRY data is in @inq_result; the scsi_level and INQUIRY length
565  *     are copied to the scsi_device any flags value is stored in *@bflags.
566  **/
567 static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result,
568 			  int result_len, int *bflags)
569 {
570 	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
571 	int first_inquiry_len, try_inquiry_len, next_inquiry_len;
572 	int response_len = 0;
573 	int pass, count, result;
574 	struct scsi_sense_hdr sshdr;
575 
576 	*bflags = 0;
577 
578 	/* Perform up to 3 passes.  The first pass uses a conservative
579 	 * transfer length of 36 unless sdev->inquiry_len specifies a
580 	 * different value. */
581 	first_inquiry_len = sdev->inquiry_len ? sdev->inquiry_len : 36;
582 	try_inquiry_len = first_inquiry_len;
583 	pass = 1;
584 
585  next_pass:
586 	SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
587 				"scsi scan: INQUIRY pass %d length %d\n",
588 				pass, try_inquiry_len));
589 
590 	/* Each pass gets up to three chances to ignore Unit Attention */
591 	for (count = 0; count < 3; ++count) {
592 		int resid;
593 
594 		memset(scsi_cmd, 0, 6);
595 		scsi_cmd[0] = INQUIRY;
596 		scsi_cmd[4] = (unsigned char) try_inquiry_len;
597 
598 		memset(inq_result, 0, try_inquiry_len);
599 
600 		result = scsi_execute_req(sdev,  scsi_cmd, DMA_FROM_DEVICE,
601 					  inq_result, try_inquiry_len, &sshdr,
602 					  HZ / 2 + HZ * scsi_inq_timeout, 3,
603 					  &resid);
604 
605 		SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
606 				"scsi scan: INQUIRY %s with code 0x%x\n",
607 				result ? "failed" : "successful", result));
608 
609 		if (result) {
610 			/*
611 			 * not-ready to ready transition [asc/ascq=0x28/0x0]
612 			 * or power-on, reset [asc/ascq=0x29/0x0], continue.
613 			 * INQUIRY should not yield UNIT_ATTENTION
614 			 * but many buggy devices do so anyway.
615 			 */
616 			if ((driver_byte(result) & DRIVER_SENSE) &&
617 			    scsi_sense_valid(&sshdr)) {
618 				if ((sshdr.sense_key == UNIT_ATTENTION) &&
619 				    ((sshdr.asc == 0x28) ||
620 				     (sshdr.asc == 0x29)) &&
621 				    (sshdr.ascq == 0))
622 					continue;
623 			}
624 		} else {
625 			/*
626 			 * if nothing was transferred, we try
627 			 * again. It's a workaround for some USB
628 			 * devices.
629 			 */
630 			if (resid == try_inquiry_len)
631 				continue;
632 		}
633 		break;
634 	}
635 
636 	if (result == 0) {
637 		scsi_sanitize_inquiry_string(&inq_result[8], 8);
638 		scsi_sanitize_inquiry_string(&inq_result[16], 16);
639 		scsi_sanitize_inquiry_string(&inq_result[32], 4);
640 
641 		response_len = inq_result[4] + 5;
642 		if (response_len > 255)
643 			response_len = first_inquiry_len;	/* sanity */
644 
645 		/*
646 		 * Get any flags for this device.
647 		 *
648 		 * XXX add a bflags to scsi_device, and replace the
649 		 * corresponding bit fields in scsi_device, so bflags
650 		 * need not be passed as an argument.
651 		 */
652 		*bflags = scsi_get_device_flags(sdev, &inq_result[8],
653 				&inq_result[16]);
654 
655 		/* When the first pass succeeds we gain information about
656 		 * what larger transfer lengths might work. */
657 		if (pass == 1) {
658 			if (BLIST_INQUIRY_36 & *bflags)
659 				next_inquiry_len = 36;
660 			else if (sdev->inquiry_len)
661 				next_inquiry_len = sdev->inquiry_len;
662 			else
663 				next_inquiry_len = response_len;
664 
665 			/* If more data is available perform the second pass */
666 			if (next_inquiry_len > try_inquiry_len) {
667 				try_inquiry_len = next_inquiry_len;
668 				pass = 2;
669 				goto next_pass;
670 			}
671 		}
672 
673 	} else if (pass == 2) {
674 		sdev_printk(KERN_INFO, sdev,
675 			    "scsi scan: %d byte inquiry failed.  "
676 			    "Consider BLIST_INQUIRY_36 for this device\n",
677 			    try_inquiry_len);
678 
679 		/* If this pass failed, the third pass goes back and transfers
680 		 * the same amount as we successfully got in the first pass. */
681 		try_inquiry_len = first_inquiry_len;
682 		pass = 3;
683 		goto next_pass;
684 	}
685 
686 	/* If the last transfer attempt got an error, assume the
687 	 * peripheral doesn't exist or is dead. */
688 	if (result)
689 		return -EIO;
690 
691 	/* Don't report any more data than the device says is valid */
692 	sdev->inquiry_len = min(try_inquiry_len, response_len);
693 
694 	/*
695 	 * XXX Abort if the response length is less than 36? If less than
696 	 * 32, the lookup of the device flags (above) could be invalid,
697 	 * and it would be possible to take an incorrect action - we do
698 	 * not want to hang because of a short INQUIRY. On the flip side,
699 	 * if the device is spun down or becoming ready (and so it gives a
700 	 * short INQUIRY), an abort here prevents any further use of the
701 	 * device, including spin up.
702 	 *
703 	 * On the whole, the best approach seems to be to assume the first
704 	 * 36 bytes are valid no matter what the device says.  That's
705 	 * better than copying < 36 bytes to the inquiry-result buffer
706 	 * and displaying garbage for the Vendor, Product, or Revision
707 	 * strings.
708 	 */
709 	if (sdev->inquiry_len < 36) {
710 		if (!sdev->host->short_inquiry) {
711 			shost_printk(KERN_INFO, sdev->host,
712 				    "scsi scan: INQUIRY result too short (%d),"
713 				    " using 36\n", sdev->inquiry_len);
714 			sdev->host->short_inquiry = 1;
715 		}
716 		sdev->inquiry_len = 36;
717 	}
718 
719 	/*
720 	 * Related to the above issue:
721 	 *
722 	 * XXX Devices (disk or all?) should be sent a TEST UNIT READY,
723 	 * and if not ready, sent a START_STOP to start (maybe spin up) and
724 	 * then send the INQUIRY again, since the INQUIRY can change after
725 	 * a device is initialized.
726 	 *
727 	 * Ideally, start a device if explicitly asked to do so.  This
728 	 * assumes that a device is spun up on power on, spun down on
729 	 * request, and then spun up on request.
730 	 */
731 
732 	/*
733 	 * The scanning code needs to know the scsi_level, even if no
734 	 * device is attached at LUN 0 (SCSI_SCAN_TARGET_PRESENT) so
735 	 * non-zero LUNs can be scanned.
736 	 */
737 	sdev->scsi_level = inq_result[2] & 0x07;
738 	if (sdev->scsi_level >= 2 ||
739 	    (sdev->scsi_level == 1 && (inq_result[3] & 0x0f) == 1))
740 		sdev->scsi_level++;
741 	sdev->sdev_target->scsi_level = sdev->scsi_level;
742 
743 	/*
744 	 * If SCSI-2 or lower, and if the transport requires it,
745 	 * store the LUN value in CDB[1].
746 	 */
747 	sdev->lun_in_cdb = 0;
748 	if (sdev->scsi_level <= SCSI_2 &&
749 	    sdev->scsi_level != SCSI_UNKNOWN &&
750 	    !sdev->host->no_scsi2_lun_in_cdb)
751 		sdev->lun_in_cdb = 1;
752 
753 	return 0;
754 }
755 
756 /**
757  * scsi_add_lun - allocate and fully initialze a scsi_device
758  * @sdev:	holds information to be stored in the new scsi_device
759  * @inq_result:	holds the result of a previous INQUIRY to the LUN
760  * @bflags:	black/white list flag
761  * @async:	1 if this device is being scanned asynchronously
762  *
763  * Description:
764  *     Initialize the scsi_device @sdev.  Optionally set fields based
765  *     on values in *@bflags.
766  *
767  * Return:
768  *     SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
769  *     SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
770  **/
771 static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
772 		int *bflags, int async)
773 {
774 	int ret;
775 
776 	/*
777 	 * XXX do not save the inquiry, since it can change underneath us,
778 	 * save just vendor/model/rev.
779 	 *
780 	 * Rather than save it and have an ioctl that retrieves the saved
781 	 * value, have an ioctl that executes the same INQUIRY code used
782 	 * in scsi_probe_lun, let user level programs doing INQUIRY
783 	 * scanning run at their own risk, or supply a user level program
784 	 * that can correctly scan.
785 	 */
786 
787 	/*
788 	 * Copy at least 36 bytes of INQUIRY data, so that we don't
789 	 * dereference unallocated memory when accessing the Vendor,
790 	 * Product, and Revision strings.  Badly behaved devices may set
791 	 * the INQUIRY Additional Length byte to a small value, indicating
792 	 * these strings are invalid, but often they contain plausible data
793 	 * nonetheless.  It doesn't matter if the device sent < 36 bytes
794 	 * total, since scsi_probe_lun() initializes inq_result with 0s.
795 	 */
796 	sdev->inquiry = kmemdup(inq_result,
797 				max_t(size_t, sdev->inquiry_len, 36),
798 				GFP_ATOMIC);
799 	if (sdev->inquiry == NULL)
800 		return SCSI_SCAN_NO_RESPONSE;
801 
802 	sdev->vendor = (char *) (sdev->inquiry + 8);
803 	sdev->model = (char *) (sdev->inquiry + 16);
804 	sdev->rev = (char *) (sdev->inquiry + 32);
805 
806 	if (strncmp(sdev->vendor, "ATA     ", 8) == 0) {
807 		/*
808 		 * sata emulation layer device.  This is a hack to work around
809 		 * the SATL power management specifications which state that
810 		 * when the SATL detects the device has gone into standby
811 		 * mode, it shall respond with NOT READY.
812 		 */
813 		sdev->allow_restart = 1;
814 	}
815 
816 	if (*bflags & BLIST_ISROM) {
817 		sdev->type = TYPE_ROM;
818 		sdev->removable = 1;
819 	} else {
820 		sdev->type = (inq_result[0] & 0x1f);
821 		sdev->removable = (inq_result[1] & 0x80) >> 7;
822 
823 		/*
824 		 * some devices may respond with wrong type for
825 		 * well-known logical units. Force well-known type
826 		 * to enumerate them correctly.
827 		 */
828 		if (scsi_is_wlun(sdev->lun) && sdev->type != TYPE_WLUN) {
829 			sdev_printk(KERN_WARNING, sdev,
830 				"%s: correcting incorrect peripheral device type 0x%x for W-LUN 0x%16xhN\n",
831 				__func__, sdev->type, (unsigned int)sdev->lun);
832 			sdev->type = TYPE_WLUN;
833 		}
834 
835 	}
836 
837 	if (sdev->type == TYPE_RBC || sdev->type == TYPE_ROM) {
838 		/* RBC and MMC devices can return SCSI-3 compliance and yet
839 		 * still not support REPORT LUNS, so make them act as
840 		 * BLIST_NOREPORTLUN unless BLIST_REPORTLUN2 is
841 		 * specifically set */
842 		if ((*bflags & BLIST_REPORTLUN2) == 0)
843 			*bflags |= BLIST_NOREPORTLUN;
844 	}
845 
846 	/*
847 	 * For a peripheral qualifier (PQ) value of 1 (001b), the SCSI
848 	 * spec says: The device server is capable of supporting the
849 	 * specified peripheral device type on this logical unit. However,
850 	 * the physical device is not currently connected to this logical
851 	 * unit.
852 	 *
853 	 * The above is vague, as it implies that we could treat 001 and
854 	 * 011 the same. Stay compatible with previous code, and create a
855 	 * scsi_device for a PQ of 1
856 	 *
857 	 * Don't set the device offline here; rather let the upper
858 	 * level drivers eval the PQ to decide whether they should
859 	 * attach. So remove ((inq_result[0] >> 5) & 7) == 1 check.
860 	 */
861 
862 	sdev->inq_periph_qual = (inq_result[0] >> 5) & 7;
863 	sdev->lockable = sdev->removable;
864 	sdev->soft_reset = (inq_result[7] & 1) && ((inq_result[3] & 7) == 2);
865 
866 	if (sdev->scsi_level >= SCSI_3 ||
867 			(sdev->inquiry_len > 56 && inq_result[56] & 0x04))
868 		sdev->ppr = 1;
869 	if (inq_result[7] & 0x60)
870 		sdev->wdtr = 1;
871 	if (inq_result[7] & 0x10)
872 		sdev->sdtr = 1;
873 
874 	sdev_printk(KERN_NOTICE, sdev, "%s %.8s %.16s %.4s PQ: %d "
875 			"ANSI: %d%s\n", scsi_device_type(sdev->type),
876 			sdev->vendor, sdev->model, sdev->rev,
877 			sdev->inq_periph_qual, inq_result[2] & 0x07,
878 			(inq_result[3] & 0x0f) == 1 ? " CCS" : "");
879 
880 	if ((sdev->scsi_level >= SCSI_2) && (inq_result[7] & 2) &&
881 	    !(*bflags & BLIST_NOTQ)) {
882 		sdev->tagged_supported = 1;
883 		sdev->simple_tags = 1;
884 	}
885 
886 	/*
887 	 * Some devices (Texel CD ROM drives) have handshaking problems
888 	 * when used with the Seagate controllers. borken is initialized
889 	 * to 1, and then set it to 0 here.
890 	 */
891 	if ((*bflags & BLIST_BORKEN) == 0)
892 		sdev->borken = 0;
893 
894 	if (*bflags & BLIST_NO_ULD_ATTACH)
895 		sdev->no_uld_attach = 1;
896 
897 	/*
898 	 * Apparently some really broken devices (contrary to the SCSI
899 	 * standards) need to be selected without asserting ATN
900 	 */
901 	if (*bflags & BLIST_SELECT_NO_ATN)
902 		sdev->select_no_atn = 1;
903 
904 	/*
905 	 * Maximum 512 sector transfer length
906 	 * broken RA4x00 Compaq Disk Array
907 	 */
908 	if (*bflags & BLIST_MAX_512)
909 		blk_queue_max_hw_sectors(sdev->request_queue, 512);
910 	/*
911 	 * Max 1024 sector transfer length for targets that report incorrect
912 	 * max/optimal lengths and relied on the old block layer safe default
913 	 */
914 	else if (*bflags & BLIST_MAX_1024)
915 		blk_queue_max_hw_sectors(sdev->request_queue, 1024);
916 
917 	/*
918 	 * Some devices may not want to have a start command automatically
919 	 * issued when a device is added.
920 	 */
921 	if (*bflags & BLIST_NOSTARTONADD)
922 		sdev->no_start_on_add = 1;
923 
924 	if (*bflags & BLIST_SINGLELUN)
925 		scsi_target(sdev)->single_lun = 1;
926 
927 	sdev->use_10_for_rw = 1;
928 
929 	/* some devices don't like REPORT SUPPORTED OPERATION CODES
930 	 * and will simply timeout causing sd_mod init to take a very
931 	 * very long time */
932 	if (*bflags & BLIST_NO_RSOC)
933 		sdev->no_report_opcodes = 1;
934 
935 	/* set the device running here so that slave configure
936 	 * may do I/O */
937 	mutex_lock(&sdev->state_mutex);
938 	ret = scsi_device_set_state(sdev, SDEV_RUNNING);
939 	if (ret)
940 		ret = scsi_device_set_state(sdev, SDEV_BLOCK);
941 	mutex_unlock(&sdev->state_mutex);
942 
943 	if (ret) {
944 		sdev_printk(KERN_ERR, sdev,
945 			    "in wrong state %s to complete scan\n",
946 			    scsi_device_state_name(sdev->sdev_state));
947 		return SCSI_SCAN_NO_RESPONSE;
948 	}
949 
950 	if (*bflags & BLIST_NOT_LOCKABLE)
951 		sdev->lockable = 0;
952 
953 	if (*bflags & BLIST_RETRY_HWERROR)
954 		sdev->retry_hwerror = 1;
955 
956 	if (*bflags & BLIST_NO_DIF)
957 		sdev->no_dif = 1;
958 
959 	if (*bflags & BLIST_UNMAP_LIMIT_WS)
960 		sdev->unmap_limit_for_ws = 1;
961 
962 	sdev->eh_timeout = SCSI_DEFAULT_EH_TIMEOUT;
963 
964 	if (*bflags & BLIST_TRY_VPD_PAGES)
965 		sdev->try_vpd_pages = 1;
966 	else if (*bflags & BLIST_SKIP_VPD_PAGES)
967 		sdev->skip_vpd_pages = 1;
968 
969 	transport_configure_device(&sdev->sdev_gendev);
970 
971 	if (sdev->host->hostt->slave_configure) {
972 		ret = sdev->host->hostt->slave_configure(sdev);
973 		if (ret) {
974 			/*
975 			 * if LLDD reports slave not present, don't clutter
976 			 * console with alloc failure messages
977 			 */
978 			if (ret != -ENXIO) {
979 				sdev_printk(KERN_ERR, sdev,
980 					"failed to configure device\n");
981 			}
982 			return SCSI_SCAN_NO_RESPONSE;
983 		}
984 	}
985 
986 	if (sdev->scsi_level >= SCSI_3)
987 		scsi_attach_vpd(sdev);
988 
989 	sdev->max_queue_depth = sdev->queue_depth;
990 
991 	/*
992 	 * Ok, the device is now all set up, we can
993 	 * register it and tell the rest of the kernel
994 	 * about it.
995 	 */
996 	if (!async && scsi_sysfs_add_sdev(sdev) != 0)
997 		return SCSI_SCAN_NO_RESPONSE;
998 
999 	return SCSI_SCAN_LUN_PRESENT;
1000 }
1001 
1002 #ifdef CONFIG_SCSI_LOGGING
1003 /**
1004  * scsi_inq_str - print INQUIRY data from min to max index, strip trailing whitespace
1005  * @buf:   Output buffer with at least end-first+1 bytes of space
1006  * @inq:   Inquiry buffer (input)
1007  * @first: Offset of string into inq
1008  * @end:   Index after last character in inq
1009  */
1010 static unsigned char *scsi_inq_str(unsigned char *buf, unsigned char *inq,
1011 				   unsigned first, unsigned end)
1012 {
1013 	unsigned term = 0, idx;
1014 
1015 	for (idx = 0; idx + first < end && idx + first < inq[4] + 5; idx++) {
1016 		if (inq[idx+first] > ' ') {
1017 			buf[idx] = inq[idx+first];
1018 			term = idx+1;
1019 		} else {
1020 			buf[idx] = ' ';
1021 		}
1022 	}
1023 	buf[term] = 0;
1024 	return buf;
1025 }
1026 #endif
1027 
1028 /**
1029  * scsi_probe_and_add_lun - probe a LUN, if a LUN is found add it
1030  * @starget:	pointer to target device structure
1031  * @lun:	LUN of target device
1032  * @bflagsp:	store bflags here if not NULL
1033  * @sdevp:	probe the LUN corresponding to this scsi_device
1034  * @rescan:     if not equal to SCSI_SCAN_INITIAL skip some code only
1035  *              needed on first scan
1036  * @hostdata:	passed to scsi_alloc_sdev()
1037  *
1038  * Description:
1039  *     Call scsi_probe_lun, if a LUN with an attached device is found,
1040  *     allocate and set it up by calling scsi_add_lun.
1041  *
1042  * Return:
1043  *
1044  *   - SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
1045  *   - SCSI_SCAN_TARGET_PRESENT: target responded, but no device is
1046  *         attached at the LUN
1047  *   - SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
1048  **/
1049 static int scsi_probe_and_add_lun(struct scsi_target *starget,
1050 				  u64 lun, int *bflagsp,
1051 				  struct scsi_device **sdevp,
1052 				  enum scsi_scan_mode rescan,
1053 				  void *hostdata)
1054 {
1055 	struct scsi_device *sdev;
1056 	unsigned char *result;
1057 	int bflags, res = SCSI_SCAN_NO_RESPONSE, result_len = 256;
1058 	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1059 
1060 	/*
1061 	 * The rescan flag is used as an optimization, the first scan of a
1062 	 * host adapter calls into here with rescan == 0.
1063 	 */
1064 	sdev = scsi_device_lookup_by_target(starget, lun);
1065 	if (sdev) {
1066 		if (rescan != SCSI_SCAN_INITIAL || !scsi_device_created(sdev)) {
1067 			SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
1068 				"scsi scan: device exists on %s\n",
1069 				dev_name(&sdev->sdev_gendev)));
1070 			if (sdevp)
1071 				*sdevp = sdev;
1072 			else
1073 				scsi_device_put(sdev);
1074 
1075 			if (bflagsp)
1076 				*bflagsp = scsi_get_device_flags(sdev,
1077 								 sdev->vendor,
1078 								 sdev->model);
1079 			return SCSI_SCAN_LUN_PRESENT;
1080 		}
1081 		scsi_device_put(sdev);
1082 	} else
1083 		sdev = scsi_alloc_sdev(starget, lun, hostdata);
1084 	if (!sdev)
1085 		goto out;
1086 
1087 	result = kmalloc(result_len, GFP_ATOMIC |
1088 			((shost->unchecked_isa_dma) ? __GFP_DMA : 0));
1089 	if (!result)
1090 		goto out_free_sdev;
1091 
1092 	if (scsi_probe_lun(sdev, result, result_len, &bflags))
1093 		goto out_free_result;
1094 
1095 	if (bflagsp)
1096 		*bflagsp = bflags;
1097 	/*
1098 	 * result contains valid SCSI INQUIRY data.
1099 	 */
1100 	if ((result[0] >> 5) == 3) {
1101 		/*
1102 		 * For a Peripheral qualifier 3 (011b), the SCSI
1103 		 * spec says: The device server is not capable of
1104 		 * supporting a physical device on this logical
1105 		 * unit.
1106 		 *
1107 		 * For disks, this implies that there is no
1108 		 * logical disk configured at sdev->lun, but there
1109 		 * is a target id responding.
1110 		 */
1111 		SCSI_LOG_SCAN_BUS(2, sdev_printk(KERN_INFO, sdev, "scsi scan:"
1112 				   " peripheral qualifier of 3, device not"
1113 				   " added\n"))
1114 		if (lun == 0) {
1115 			SCSI_LOG_SCAN_BUS(1, {
1116 				unsigned char vend[9];
1117 				unsigned char mod[17];
1118 
1119 				sdev_printk(KERN_INFO, sdev,
1120 					"scsi scan: consider passing scsi_mod."
1121 					"dev_flags=%s:%s:0x240 or 0x1000240\n",
1122 					scsi_inq_str(vend, result, 8, 16),
1123 					scsi_inq_str(mod, result, 16, 32));
1124 			});
1125 
1126 		}
1127 
1128 		res = SCSI_SCAN_TARGET_PRESENT;
1129 		goto out_free_result;
1130 	}
1131 
1132 	/*
1133 	 * Some targets may set slight variations of PQ and PDT to signal
1134 	 * that no LUN is present, so don't add sdev in these cases.
1135 	 * Two specific examples are:
1136 	 * 1) NetApp targets: return PQ=1, PDT=0x1f
1137 	 * 2) USB UFI: returns PDT=0x1f, with the PQ bits being "reserved"
1138 	 *    in the UFI 1.0 spec (we cannot rely on reserved bits).
1139 	 *
1140 	 * References:
1141 	 * 1) SCSI SPC-3, pp. 145-146
1142 	 * PQ=1: "A peripheral device having the specified peripheral
1143 	 * device type is not connected to this logical unit. However, the
1144 	 * device server is capable of supporting the specified peripheral
1145 	 * device type on this logical unit."
1146 	 * PDT=0x1f: "Unknown or no device type"
1147 	 * 2) USB UFI 1.0, p. 20
1148 	 * PDT=00h Direct-access device (floppy)
1149 	 * PDT=1Fh none (no FDD connected to the requested logical unit)
1150 	 */
1151 	if (((result[0] >> 5) == 1 || starget->pdt_1f_for_no_lun) &&
1152 	    (result[0] & 0x1f) == 0x1f &&
1153 	    !scsi_is_wlun(lun)) {
1154 		SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
1155 					"scsi scan: peripheral device type"
1156 					" of 31, no device added\n"));
1157 		res = SCSI_SCAN_TARGET_PRESENT;
1158 		goto out_free_result;
1159 	}
1160 
1161 	res = scsi_add_lun(sdev, result, &bflags, shost->async_scan);
1162 	if (res == SCSI_SCAN_LUN_PRESENT) {
1163 		if (bflags & BLIST_KEY) {
1164 			sdev->lockable = 0;
1165 			scsi_unlock_floptical(sdev, result);
1166 		}
1167 	}
1168 
1169  out_free_result:
1170 	kfree(result);
1171  out_free_sdev:
1172 	if (res == SCSI_SCAN_LUN_PRESENT) {
1173 		if (sdevp) {
1174 			if (scsi_device_get(sdev) == 0) {
1175 				*sdevp = sdev;
1176 			} else {
1177 				__scsi_remove_device(sdev);
1178 				res = SCSI_SCAN_NO_RESPONSE;
1179 			}
1180 		}
1181 	} else
1182 		__scsi_remove_device(sdev);
1183  out:
1184 	return res;
1185 }
1186 
1187 /**
1188  * scsi_sequential_lun_scan - sequentially scan a SCSI target
1189  * @starget:	pointer to target structure to scan
1190  * @bflags:	black/white list flag for LUN 0
1191  * @scsi_level: Which version of the standard does this device adhere to
1192  * @rescan:     passed to scsi_probe_add_lun()
1193  *
1194  * Description:
1195  *     Generally, scan from LUN 1 (LUN 0 is assumed to already have been
1196  *     scanned) to some maximum lun until a LUN is found with no device
1197  *     attached. Use the bflags to figure out any oddities.
1198  *
1199  *     Modifies sdevscan->lun.
1200  **/
1201 static void scsi_sequential_lun_scan(struct scsi_target *starget,
1202 				     int bflags, int scsi_level,
1203 				     enum scsi_scan_mode rescan)
1204 {
1205 	uint max_dev_lun;
1206 	u64 sparse_lun, lun;
1207 	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1208 
1209 	SCSI_LOG_SCAN_BUS(3, starget_printk(KERN_INFO, starget,
1210 		"scsi scan: Sequential scan\n"));
1211 
1212 	max_dev_lun = min(max_scsi_luns, shost->max_lun);
1213 	/*
1214 	 * If this device is known to support sparse multiple units,
1215 	 * override the other settings, and scan all of them. Normally,
1216 	 * SCSI-3 devices should be scanned via the REPORT LUNS.
1217 	 */
1218 	if (bflags & BLIST_SPARSELUN) {
1219 		max_dev_lun = shost->max_lun;
1220 		sparse_lun = 1;
1221 	} else
1222 		sparse_lun = 0;
1223 
1224 	/*
1225 	 * If less than SCSI_1_CCS, and no special lun scanning, stop
1226 	 * scanning; this matches 2.4 behaviour, but could just be a bug
1227 	 * (to continue scanning a SCSI_1_CCS device).
1228 	 *
1229 	 * This test is broken.  We might not have any device on lun0 for
1230 	 * a sparselun device, and if that's the case then how would we
1231 	 * know the real scsi_level, eh?  It might make sense to just not
1232 	 * scan any SCSI_1 device for non-0 luns, but that check would best
1233 	 * go into scsi_alloc_sdev() and just have it return null when asked
1234 	 * to alloc an sdev for lun > 0 on an already found SCSI_1 device.
1235 	 *
1236 	if ((sdevscan->scsi_level < SCSI_1_CCS) &&
1237 	    ((bflags & (BLIST_FORCELUN | BLIST_SPARSELUN | BLIST_MAX5LUN))
1238 	     == 0))
1239 		return;
1240 	 */
1241 	/*
1242 	 * If this device is known to support multiple units, override
1243 	 * the other settings, and scan all of them.
1244 	 */
1245 	if (bflags & BLIST_FORCELUN)
1246 		max_dev_lun = shost->max_lun;
1247 	/*
1248 	 * REGAL CDC-4X: avoid hang after LUN 4
1249 	 */
1250 	if (bflags & BLIST_MAX5LUN)
1251 		max_dev_lun = min(5U, max_dev_lun);
1252 	/*
1253 	 * Do not scan SCSI-2 or lower device past LUN 7, unless
1254 	 * BLIST_LARGELUN.
1255 	 */
1256 	if (scsi_level < SCSI_3 && !(bflags & BLIST_LARGELUN))
1257 		max_dev_lun = min(8U, max_dev_lun);
1258 	else
1259 		max_dev_lun = min(256U, max_dev_lun);
1260 
1261 	/*
1262 	 * We have already scanned LUN 0, so start at LUN 1. Keep scanning
1263 	 * until we reach the max, or no LUN is found and we are not
1264 	 * sparse_lun.
1265 	 */
1266 	for (lun = 1; lun < max_dev_lun; ++lun)
1267 		if ((scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan,
1268 					    NULL) != SCSI_SCAN_LUN_PRESENT) &&
1269 		    !sparse_lun)
1270 			return;
1271 }
1272 
1273 /**
1274  * scsi_report_lun_scan - Scan using SCSI REPORT LUN results
1275  * @starget: which target
1276  * @bflags: Zero or a mix of BLIST_NOLUN, BLIST_REPORTLUN2, or BLIST_NOREPORTLUN
1277  * @rescan: nonzero if we can skip code only needed on first scan
1278  *
1279  * Description:
1280  *   Fast scanning for modern (SCSI-3) devices by sending a REPORT LUN command.
1281  *   Scan the resulting list of LUNs by calling scsi_probe_and_add_lun.
1282  *
1283  *   If BLINK_REPORTLUN2 is set, scan a target that supports more than 8
1284  *   LUNs even if it's older than SCSI-3.
1285  *   If BLIST_NOREPORTLUN is set, return 1 always.
1286  *   If BLIST_NOLUN is set, return 0 always.
1287  *   If starget->no_report_luns is set, return 1 always.
1288  *
1289  * Return:
1290  *     0: scan completed (or no memory, so further scanning is futile)
1291  *     1: could not scan with REPORT LUN
1292  **/
1293 static int scsi_report_lun_scan(struct scsi_target *starget, int bflags,
1294 				enum scsi_scan_mode rescan)
1295 {
1296 	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
1297 	unsigned int length;
1298 	u64 lun;
1299 	unsigned int num_luns;
1300 	unsigned int retries;
1301 	int result;
1302 	struct scsi_lun *lunp, *lun_data;
1303 	struct scsi_sense_hdr sshdr;
1304 	struct scsi_device *sdev;
1305 	struct Scsi_Host *shost = dev_to_shost(&starget->dev);
1306 	int ret = 0;
1307 
1308 	/*
1309 	 * Only support SCSI-3 and up devices if BLIST_NOREPORTLUN is not set.
1310 	 * Also allow SCSI-2 if BLIST_REPORTLUN2 is set and host adapter does
1311 	 * support more than 8 LUNs.
1312 	 * Don't attempt if the target doesn't support REPORT LUNS.
1313 	 */
1314 	if (bflags & BLIST_NOREPORTLUN)
1315 		return 1;
1316 	if (starget->scsi_level < SCSI_2 &&
1317 	    starget->scsi_level != SCSI_UNKNOWN)
1318 		return 1;
1319 	if (starget->scsi_level < SCSI_3 &&
1320 	    (!(bflags & BLIST_REPORTLUN2) || shost->max_lun <= 8))
1321 		return 1;
1322 	if (bflags & BLIST_NOLUN)
1323 		return 0;
1324 	if (starget->no_report_luns)
1325 		return 1;
1326 
1327 	if (!(sdev = scsi_device_lookup_by_target(starget, 0))) {
1328 		sdev = scsi_alloc_sdev(starget, 0, NULL);
1329 		if (!sdev)
1330 			return 0;
1331 		if (scsi_device_get(sdev)) {
1332 			__scsi_remove_device(sdev);
1333 			return 0;
1334 		}
1335 	}
1336 
1337 	/*
1338 	 * Allocate enough to hold the header (the same size as one scsi_lun)
1339 	 * plus the number of luns we are requesting.  511 was the default
1340 	 * value of the now removed max_report_luns parameter.
1341 	 */
1342 	length = (511 + 1) * sizeof(struct scsi_lun);
1343 retry:
1344 	lun_data = kmalloc(length, GFP_KERNEL |
1345 			   (sdev->host->unchecked_isa_dma ? __GFP_DMA : 0));
1346 	if (!lun_data) {
1347 		printk(ALLOC_FAILURE_MSG, __func__);
1348 		goto out;
1349 	}
1350 
1351 	scsi_cmd[0] = REPORT_LUNS;
1352 
1353 	/*
1354 	 * bytes 1 - 5: reserved, set to zero.
1355 	 */
1356 	memset(&scsi_cmd[1], 0, 5);
1357 
1358 	/*
1359 	 * bytes 6 - 9: length of the command.
1360 	 */
1361 	put_unaligned_be32(length, &scsi_cmd[6]);
1362 
1363 	scsi_cmd[10] = 0;	/* reserved */
1364 	scsi_cmd[11] = 0;	/* control */
1365 
1366 	/*
1367 	 * We can get a UNIT ATTENTION, for example a power on/reset, so
1368 	 * retry a few times (like sd.c does for TEST UNIT READY).
1369 	 * Experience shows some combinations of adapter/devices get at
1370 	 * least two power on/resets.
1371 	 *
1372 	 * Illegal requests (for devices that do not support REPORT LUNS)
1373 	 * should come through as a check condition, and will not generate
1374 	 * a retry.
1375 	 */
1376 	for (retries = 0; retries < 3; retries++) {
1377 		SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1378 				"scsi scan: Sending REPORT LUNS to (try %d)\n",
1379 				retries));
1380 
1381 		result = scsi_execute_req(sdev, scsi_cmd, DMA_FROM_DEVICE,
1382 					  lun_data, length, &sshdr,
1383 					  SCSI_REPORT_LUNS_TIMEOUT, 3, NULL);
1384 
1385 		SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1386 				"scsi scan: REPORT LUNS"
1387 				" %s (try %d) result 0x%x\n",
1388 				result ?  "failed" : "successful",
1389 				retries, result));
1390 		if (result == 0)
1391 			break;
1392 		else if (scsi_sense_valid(&sshdr)) {
1393 			if (sshdr.sense_key != UNIT_ATTENTION)
1394 				break;
1395 		}
1396 	}
1397 
1398 	if (result) {
1399 		/*
1400 		 * The device probably does not support a REPORT LUN command
1401 		 */
1402 		ret = 1;
1403 		goto out_err;
1404 	}
1405 
1406 	/*
1407 	 * Get the length from the first four bytes of lun_data.
1408 	 */
1409 	if (get_unaligned_be32(lun_data->scsi_lun) +
1410 	    sizeof(struct scsi_lun) > length) {
1411 		length = get_unaligned_be32(lun_data->scsi_lun) +
1412 			 sizeof(struct scsi_lun);
1413 		kfree(lun_data);
1414 		goto retry;
1415 	}
1416 	length = get_unaligned_be32(lun_data->scsi_lun);
1417 
1418 	num_luns = (length / sizeof(struct scsi_lun));
1419 
1420 	SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1421 		"scsi scan: REPORT LUN scan\n"));
1422 
1423 	/*
1424 	 * Scan the luns in lun_data. The entry at offset 0 is really
1425 	 * the header, so start at 1 and go up to and including num_luns.
1426 	 */
1427 	for (lunp = &lun_data[1]; lunp <= &lun_data[num_luns]; lunp++) {
1428 		lun = scsilun_to_int(lunp);
1429 
1430 		if (lun > sdev->host->max_lun) {
1431 			sdev_printk(KERN_WARNING, sdev,
1432 				    "lun%llu has a LUN larger than"
1433 				    " allowed by the host adapter\n", lun);
1434 		} else {
1435 			int res;
1436 
1437 			res = scsi_probe_and_add_lun(starget,
1438 				lun, NULL, NULL, rescan, NULL);
1439 			if (res == SCSI_SCAN_NO_RESPONSE) {
1440 				/*
1441 				 * Got some results, but now none, abort.
1442 				 */
1443 				sdev_printk(KERN_ERR, sdev,
1444 					"Unexpected response"
1445 					" from lun %llu while scanning, scan"
1446 					" aborted\n", (unsigned long long)lun);
1447 				break;
1448 			}
1449 		}
1450 	}
1451 
1452  out_err:
1453 	kfree(lun_data);
1454  out:
1455 	if (scsi_device_created(sdev))
1456 		/*
1457 		 * the sdev we used didn't appear in the report luns scan
1458 		 */
1459 		__scsi_remove_device(sdev);
1460 	scsi_device_put(sdev);
1461 	return ret;
1462 }
1463 
1464 struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
1465 				      uint id, u64 lun, void *hostdata)
1466 {
1467 	struct scsi_device *sdev = ERR_PTR(-ENODEV);
1468 	struct device *parent = &shost->shost_gendev;
1469 	struct scsi_target *starget;
1470 
1471 	if (strncmp(scsi_scan_type, "none", 4) == 0)
1472 		return ERR_PTR(-ENODEV);
1473 
1474 	starget = scsi_alloc_target(parent, channel, id);
1475 	if (!starget)
1476 		return ERR_PTR(-ENOMEM);
1477 	scsi_autopm_get_target(starget);
1478 
1479 	mutex_lock(&shost->scan_mutex);
1480 	if (!shost->async_scan)
1481 		scsi_complete_async_scans();
1482 
1483 	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1484 		scsi_probe_and_add_lun(starget, lun, NULL, &sdev, 1, hostdata);
1485 		scsi_autopm_put_host(shost);
1486 	}
1487 	mutex_unlock(&shost->scan_mutex);
1488 	scsi_autopm_put_target(starget);
1489 	/*
1490 	 * paired with scsi_alloc_target().  Target will be destroyed unless
1491 	 * scsi_probe_and_add_lun made an underlying device visible
1492 	 */
1493 	scsi_target_reap(starget);
1494 	put_device(&starget->dev);
1495 
1496 	return sdev;
1497 }
1498 EXPORT_SYMBOL(__scsi_add_device);
1499 
1500 int scsi_add_device(struct Scsi_Host *host, uint channel,
1501 		    uint target, u64 lun)
1502 {
1503 	struct scsi_device *sdev =
1504 		__scsi_add_device(host, channel, target, lun, NULL);
1505 	if (IS_ERR(sdev))
1506 		return PTR_ERR(sdev);
1507 
1508 	scsi_device_put(sdev);
1509 	return 0;
1510 }
1511 EXPORT_SYMBOL(scsi_add_device);
1512 
1513 void scsi_rescan_device(struct device *dev)
1514 {
1515 	struct scsi_device *sdev = to_scsi_device(dev);
1516 
1517 	device_lock(dev);
1518 
1519 	scsi_attach_vpd(sdev);
1520 
1521 	if (sdev->handler && sdev->handler->rescan)
1522 		sdev->handler->rescan(sdev);
1523 
1524 	if (dev->driver && try_module_get(dev->driver->owner)) {
1525 		struct scsi_driver *drv = to_scsi_driver(dev->driver);
1526 
1527 		if (drv->rescan)
1528 			drv->rescan(dev);
1529 		module_put(dev->driver->owner);
1530 	}
1531 	device_unlock(dev);
1532 }
1533 EXPORT_SYMBOL(scsi_rescan_device);
1534 
1535 static void __scsi_scan_target(struct device *parent, unsigned int channel,
1536 		unsigned int id, u64 lun, enum scsi_scan_mode rescan)
1537 {
1538 	struct Scsi_Host *shost = dev_to_shost(parent);
1539 	int bflags = 0;
1540 	int res;
1541 	struct scsi_target *starget;
1542 
1543 	if (shost->this_id == id)
1544 		/*
1545 		 * Don't scan the host adapter
1546 		 */
1547 		return;
1548 
1549 	starget = scsi_alloc_target(parent, channel, id);
1550 	if (!starget)
1551 		return;
1552 	scsi_autopm_get_target(starget);
1553 
1554 	if (lun != SCAN_WILD_CARD) {
1555 		/*
1556 		 * Scan for a specific host/chan/id/lun.
1557 		 */
1558 		scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan, NULL);
1559 		goto out_reap;
1560 	}
1561 
1562 	/*
1563 	 * Scan LUN 0, if there is some response, scan further. Ideally, we
1564 	 * would not configure LUN 0 until all LUNs are scanned.
1565 	 */
1566 	res = scsi_probe_and_add_lun(starget, 0, &bflags, NULL, rescan, NULL);
1567 	if (res == SCSI_SCAN_LUN_PRESENT || res == SCSI_SCAN_TARGET_PRESENT) {
1568 		if (scsi_report_lun_scan(starget, bflags, rescan) != 0)
1569 			/*
1570 			 * The REPORT LUN did not scan the target,
1571 			 * do a sequential scan.
1572 			 */
1573 			scsi_sequential_lun_scan(starget, bflags,
1574 						 starget->scsi_level, rescan);
1575 	}
1576 
1577  out_reap:
1578 	scsi_autopm_put_target(starget);
1579 	/*
1580 	 * paired with scsi_alloc_target(): determine if the target has
1581 	 * any children at all and if not, nuke it
1582 	 */
1583 	scsi_target_reap(starget);
1584 
1585 	put_device(&starget->dev);
1586 }
1587 
1588 /**
1589  * scsi_scan_target - scan a target id, possibly including all LUNs on the target.
1590  * @parent:	host to scan
1591  * @channel:	channel to scan
1592  * @id:		target id to scan
1593  * @lun:	Specific LUN to scan or SCAN_WILD_CARD
1594  * @rescan:	passed to LUN scanning routines; SCSI_SCAN_INITIAL for
1595  *              no rescan, SCSI_SCAN_RESCAN to rescan existing LUNs,
1596  *              and SCSI_SCAN_MANUAL to force scanning even if
1597  *              'scan=manual' is set.
1598  *
1599  * Description:
1600  *     Scan the target id on @parent, @channel, and @id. Scan at least LUN 0,
1601  *     and possibly all LUNs on the target id.
1602  *
1603  *     First try a REPORT LUN scan, if that does not scan the target, do a
1604  *     sequential scan of LUNs on the target id.
1605  **/
1606 void scsi_scan_target(struct device *parent, unsigned int channel,
1607 		      unsigned int id, u64 lun, enum scsi_scan_mode rescan)
1608 {
1609 	struct Scsi_Host *shost = dev_to_shost(parent);
1610 
1611 	if (strncmp(scsi_scan_type, "none", 4) == 0)
1612 		return;
1613 
1614 	if (rescan != SCSI_SCAN_MANUAL &&
1615 	    strncmp(scsi_scan_type, "manual", 6) == 0)
1616 		return;
1617 
1618 	mutex_lock(&shost->scan_mutex);
1619 	if (!shost->async_scan)
1620 		scsi_complete_async_scans();
1621 
1622 	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1623 		__scsi_scan_target(parent, channel, id, lun, rescan);
1624 		scsi_autopm_put_host(shost);
1625 	}
1626 	mutex_unlock(&shost->scan_mutex);
1627 }
1628 EXPORT_SYMBOL(scsi_scan_target);
1629 
1630 static void scsi_scan_channel(struct Scsi_Host *shost, unsigned int channel,
1631 			      unsigned int id, u64 lun,
1632 			      enum scsi_scan_mode rescan)
1633 {
1634 	uint order_id;
1635 
1636 	if (id == SCAN_WILD_CARD)
1637 		for (id = 0; id < shost->max_id; ++id) {
1638 			/*
1639 			 * XXX adapter drivers when possible (FCP, iSCSI)
1640 			 * could modify max_id to match the current max,
1641 			 * not the absolute max.
1642 			 *
1643 			 * XXX add a shost id iterator, so for example,
1644 			 * the FC ID can be the same as a target id
1645 			 * without a huge overhead of sparse id's.
1646 			 */
1647 			if (shost->reverse_ordering)
1648 				/*
1649 				 * Scan from high to low id.
1650 				 */
1651 				order_id = shost->max_id - id - 1;
1652 			else
1653 				order_id = id;
1654 			__scsi_scan_target(&shost->shost_gendev, channel,
1655 					order_id, lun, rescan);
1656 		}
1657 	else
1658 		__scsi_scan_target(&shost->shost_gendev, channel,
1659 				id, lun, rescan);
1660 }
1661 
1662 int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel,
1663 			    unsigned int id, u64 lun,
1664 			    enum scsi_scan_mode rescan)
1665 {
1666 	SCSI_LOG_SCAN_BUS(3, shost_printk (KERN_INFO, shost,
1667 		"%s: <%u:%u:%llu>\n",
1668 		__func__, channel, id, lun));
1669 
1670 	if (((channel != SCAN_WILD_CARD) && (channel > shost->max_channel)) ||
1671 	    ((id != SCAN_WILD_CARD) && (id >= shost->max_id)) ||
1672 	    ((lun != SCAN_WILD_CARD) && (lun >= shost->max_lun)))
1673 		return -EINVAL;
1674 
1675 	mutex_lock(&shost->scan_mutex);
1676 	if (!shost->async_scan)
1677 		scsi_complete_async_scans();
1678 
1679 	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1680 		if (channel == SCAN_WILD_CARD)
1681 			for (channel = 0; channel <= shost->max_channel;
1682 			     channel++)
1683 				scsi_scan_channel(shost, channel, id, lun,
1684 						  rescan);
1685 		else
1686 			scsi_scan_channel(shost, channel, id, lun, rescan);
1687 		scsi_autopm_put_host(shost);
1688 	}
1689 	mutex_unlock(&shost->scan_mutex);
1690 
1691 	return 0;
1692 }
1693 
1694 static void scsi_sysfs_add_devices(struct Scsi_Host *shost)
1695 {
1696 	struct scsi_device *sdev;
1697 	shost_for_each_device(sdev, shost) {
1698 		/* target removed before the device could be added */
1699 		if (sdev->sdev_state == SDEV_DEL)
1700 			continue;
1701 		/* If device is already visible, skip adding it to sysfs */
1702 		if (sdev->is_visible)
1703 			continue;
1704 		if (!scsi_host_scan_allowed(shost) ||
1705 		    scsi_sysfs_add_sdev(sdev) != 0)
1706 			__scsi_remove_device(sdev);
1707 	}
1708 }
1709 
1710 /**
1711  * scsi_prep_async_scan - prepare for an async scan
1712  * @shost: the host which will be scanned
1713  * Returns: a cookie to be passed to scsi_finish_async_scan()
1714  *
1715  * Tells the midlayer this host is going to do an asynchronous scan.
1716  * It reserves the host's position in the scanning list and ensures
1717  * that other asynchronous scans started after this one won't affect the
1718  * ordering of the discovered devices.
1719  */
1720 static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost)
1721 {
1722 	struct async_scan_data *data;
1723 	unsigned long flags;
1724 
1725 	if (strncmp(scsi_scan_type, "sync", 4) == 0)
1726 		return NULL;
1727 
1728 	if (shost->async_scan) {
1729 		shost_printk(KERN_DEBUG, shost, "%s called twice\n", __func__);
1730 		return NULL;
1731 	}
1732 
1733 	data = kmalloc(sizeof(*data), GFP_KERNEL);
1734 	if (!data)
1735 		goto err;
1736 	data->shost = scsi_host_get(shost);
1737 	if (!data->shost)
1738 		goto err;
1739 	init_completion(&data->prev_finished);
1740 
1741 	mutex_lock(&shost->scan_mutex);
1742 	spin_lock_irqsave(shost->host_lock, flags);
1743 	shost->async_scan = 1;
1744 	spin_unlock_irqrestore(shost->host_lock, flags);
1745 	mutex_unlock(&shost->scan_mutex);
1746 
1747 	spin_lock(&async_scan_lock);
1748 	if (list_empty(&scanning_hosts))
1749 		complete(&data->prev_finished);
1750 	list_add_tail(&data->list, &scanning_hosts);
1751 	spin_unlock(&async_scan_lock);
1752 
1753 	return data;
1754 
1755  err:
1756 	kfree(data);
1757 	return NULL;
1758 }
1759 
1760 /**
1761  * scsi_finish_async_scan - asynchronous scan has finished
1762  * @data: cookie returned from earlier call to scsi_prep_async_scan()
1763  *
1764  * All the devices currently attached to this host have been found.
1765  * This function announces all the devices it has found to the rest
1766  * of the system.
1767  */
1768 static void scsi_finish_async_scan(struct async_scan_data *data)
1769 {
1770 	struct Scsi_Host *shost;
1771 	unsigned long flags;
1772 
1773 	if (!data)
1774 		return;
1775 
1776 	shost = data->shost;
1777 
1778 	mutex_lock(&shost->scan_mutex);
1779 
1780 	if (!shost->async_scan) {
1781 		shost_printk(KERN_INFO, shost, "%s called twice\n", __func__);
1782 		dump_stack();
1783 		mutex_unlock(&shost->scan_mutex);
1784 		return;
1785 	}
1786 
1787 	wait_for_completion(&data->prev_finished);
1788 
1789 	scsi_sysfs_add_devices(shost);
1790 
1791 	spin_lock_irqsave(shost->host_lock, flags);
1792 	shost->async_scan = 0;
1793 	spin_unlock_irqrestore(shost->host_lock, flags);
1794 
1795 	mutex_unlock(&shost->scan_mutex);
1796 
1797 	spin_lock(&async_scan_lock);
1798 	list_del(&data->list);
1799 	if (!list_empty(&scanning_hosts)) {
1800 		struct async_scan_data *next = list_entry(scanning_hosts.next,
1801 				struct async_scan_data, list);
1802 		complete(&next->prev_finished);
1803 	}
1804 	spin_unlock(&async_scan_lock);
1805 
1806 	scsi_autopm_put_host(shost);
1807 	scsi_host_put(shost);
1808 	kfree(data);
1809 }
1810 
1811 static void do_scsi_scan_host(struct Scsi_Host *shost)
1812 {
1813 	if (shost->hostt->scan_finished) {
1814 		unsigned long start = jiffies;
1815 		if (shost->hostt->scan_start)
1816 			shost->hostt->scan_start(shost);
1817 
1818 		while (!shost->hostt->scan_finished(shost, jiffies - start))
1819 			msleep(10);
1820 	} else {
1821 		scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD,
1822 				SCAN_WILD_CARD, 0);
1823 	}
1824 }
1825 
1826 static void do_scan_async(void *_data, async_cookie_t c)
1827 {
1828 	struct async_scan_data *data = _data;
1829 	struct Scsi_Host *shost = data->shost;
1830 
1831 	do_scsi_scan_host(shost);
1832 	scsi_finish_async_scan(data);
1833 }
1834 
1835 /**
1836  * scsi_scan_host - scan the given adapter
1837  * @shost:	adapter to scan
1838  **/
1839 void scsi_scan_host(struct Scsi_Host *shost)
1840 {
1841 	struct async_scan_data *data;
1842 
1843 	if (strncmp(scsi_scan_type, "none", 4) == 0 ||
1844 	    strncmp(scsi_scan_type, "manual", 6) == 0)
1845 		return;
1846 	if (scsi_autopm_get_host(shost) < 0)
1847 		return;
1848 
1849 	data = scsi_prep_async_scan(shost);
1850 	if (!data) {
1851 		do_scsi_scan_host(shost);
1852 		scsi_autopm_put_host(shost);
1853 		return;
1854 	}
1855 
1856 	/* register with the async subsystem so wait_for_device_probe()
1857 	 * will flush this work
1858 	 */
1859 	async_schedule(do_scan_async, data);
1860 
1861 	/* scsi_autopm_put_host(shost) is called in scsi_finish_async_scan() */
1862 }
1863 EXPORT_SYMBOL(scsi_scan_host);
1864 
1865 void scsi_forget_host(struct Scsi_Host *shost)
1866 {
1867 	struct scsi_device *sdev;
1868 	unsigned long flags;
1869 
1870  restart:
1871 	spin_lock_irqsave(shost->host_lock, flags);
1872 	list_for_each_entry(sdev, &shost->__devices, siblings) {
1873 		if (sdev->sdev_state == SDEV_DEL)
1874 			continue;
1875 		spin_unlock_irqrestore(shost->host_lock, flags);
1876 		__scsi_remove_device(sdev);
1877 		goto restart;
1878 	}
1879 	spin_unlock_irqrestore(shost->host_lock, flags);
1880 }
1881 
1882 /**
1883  * scsi_get_host_dev - Create a scsi_device that points to the host adapter itself
1884  * @shost: Host that needs a scsi_device
1885  *
1886  * Lock status: None assumed.
1887  *
1888  * Returns:     The scsi_device or NULL
1889  *
1890  * Notes:
1891  *	Attach a single scsi_device to the Scsi_Host - this should
1892  *	be made to look like a "pseudo-device" that points to the
1893  *	HA itself.
1894  *
1895  *	Note - this device is not accessible from any high-level
1896  *	drivers (including generics), which is probably not
1897  *	optimal.  We can add hooks later to attach.
1898  */
1899 struct scsi_device *scsi_get_host_dev(struct Scsi_Host *shost)
1900 {
1901 	struct scsi_device *sdev = NULL;
1902 	struct scsi_target *starget;
1903 
1904 	mutex_lock(&shost->scan_mutex);
1905 	if (!scsi_host_scan_allowed(shost))
1906 		goto out;
1907 	starget = scsi_alloc_target(&shost->shost_gendev, 0, shost->this_id);
1908 	if (!starget)
1909 		goto out;
1910 
1911 	sdev = scsi_alloc_sdev(starget, 0, NULL);
1912 	if (sdev)
1913 		sdev->borken = 0;
1914 	else
1915 		scsi_target_reap(starget);
1916 	put_device(&starget->dev);
1917  out:
1918 	mutex_unlock(&shost->scan_mutex);
1919 	return sdev;
1920 }
1921 EXPORT_SYMBOL(scsi_get_host_dev);
1922 
1923 /**
1924  * scsi_free_host_dev - Free a scsi_device that points to the host adapter itself
1925  * @sdev: Host device to be freed
1926  *
1927  * Lock status: None assumed.
1928  *
1929  * Returns:     Nothing
1930  */
1931 void scsi_free_host_dev(struct scsi_device *sdev)
1932 {
1933 	BUG_ON(sdev->id != sdev->host->this_id);
1934 
1935 	__scsi_remove_device(sdev);
1936 }
1937 EXPORT_SYMBOL(scsi_free_host_dev);
1938 
1939