1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * scsi_scan.c
   4 *
   5 * Copyright (C) 2000 Eric Youngdale,
   6 * Copyright (C) 2002 Patrick Mansfield
   7 *
   8 * The general scanning/probing algorithm is as follows, exceptions are
   9 * made to it depending on device specific flags, compilation options, and
  10 * global variable (boot or module load time) settings.
  11 *
  12 * A specific LUN is scanned via an INQUIRY command; if the LUN has a
  13 * device attached, a scsi_device is allocated and setup for it.
  14 *
  15 * For every id of every channel on the given host:
  16 *
  17 * 	Scan LUN 0; if the target responds to LUN 0 (even if there is no
  18 * 	device or storage attached to LUN 0):
  19 *
  20 * 		If LUN 0 has a device attached, allocate and setup a
  21 * 		scsi_device for it.
  22 *
  23 * 		If target is SCSI-3 or up, issue a REPORT LUN, and scan
  24 * 		all of the LUNs returned by the REPORT LUN; else,
  25 * 		sequentially scan LUNs up until some maximum is reached,
  26 * 		or a LUN is seen that cannot have a device attached to it.
  27 */
  28
  29#include <linux/module.h>
  30#include <linux/moduleparam.h>
  31#include <linux/init.h>
  32#include <linux/blkdev.h>
  33#include <linux/delay.h>
  34#include <linux/kthread.h>
  35#include <linux/spinlock.h>
  36#include <linux/async.h>
  37#include <linux/slab.h>
  38#include <asm/unaligned.h>
  39
  40#include <scsi/scsi.h>
  41#include <scsi/scsi_cmnd.h>
  42#include <scsi/scsi_device.h>
  43#include <scsi/scsi_driver.h>
  44#include <scsi/scsi_devinfo.h>
  45#include <scsi/scsi_host.h>
  46#include <scsi/scsi_transport.h>
  47#include <scsi/scsi_dh.h>
  48#include <scsi/scsi_eh.h>
  49
  50#include "scsi_priv.h"
  51#include "scsi_logging.h"
  52
  53#define ALLOC_FAILURE_MSG	KERN_ERR "%s: Allocation failure during" \
  54	" SCSI scanning, some SCSI devices might not be configured\n"
  55
  56/*
  57 * Default timeout
  58 */
  59#define SCSI_TIMEOUT (2*HZ)
  60#define SCSI_REPORT_LUNS_TIMEOUT (30*HZ)
  61
  62/*
  63 * Prefix values for the SCSI id's (stored in sysfs name field)
  64 */
  65#define SCSI_UID_SER_NUM 'S'
  66#define SCSI_UID_UNKNOWN 'Z'
  67
  68/*
  69 * Return values of some of the scanning functions.
  70 *
  71 * SCSI_SCAN_NO_RESPONSE: no valid response received from the target, this
  72 * includes allocation or general failures preventing IO from being sent.
  73 *
  74 * SCSI_SCAN_TARGET_PRESENT: target responded, but no device is available
  75 * on the given LUN.
  76 *
  77 * SCSI_SCAN_LUN_PRESENT: target responded, and a device is available on a
  78 * given LUN.
  79 */
  80#define SCSI_SCAN_NO_RESPONSE		0
  81#define SCSI_SCAN_TARGET_PRESENT	1
  82#define SCSI_SCAN_LUN_PRESENT		2
  83
  84static const char *scsi_null_device_strs = "nullnullnullnull";
  85
  86#define MAX_SCSI_LUNS	512
  87
  88static u64 max_scsi_luns = MAX_SCSI_LUNS;
  89
  90module_param_named(max_luns, max_scsi_luns, ullong, S_IRUGO|S_IWUSR);
  91MODULE_PARM_DESC(max_luns,
  92		 "last scsi LUN (should be between 1 and 2^64-1)");
  93
  94#ifdef CONFIG_SCSI_SCAN_ASYNC
  95#define SCSI_SCAN_TYPE_DEFAULT "async"
  96#else
  97#define SCSI_SCAN_TYPE_DEFAULT "sync"
  98#endif
  99
 100char scsi_scan_type[7] = SCSI_SCAN_TYPE_DEFAULT;
 101
 102module_param_string(scan, scsi_scan_type, sizeof(scsi_scan_type),
 103		    S_IRUGO|S_IWUSR);
 104MODULE_PARM_DESC(scan, "sync, async, manual, or none. "
 105		 "Setting to 'manual' disables automatic scanning, but allows "
 106		 "for manual device scan via the 'scan' sysfs attribute.");
 107
 108static unsigned int scsi_inq_timeout = SCSI_TIMEOUT/HZ + 18;
 109
 110module_param_named(inq_timeout, scsi_inq_timeout, uint, S_IRUGO|S_IWUSR);
 111MODULE_PARM_DESC(inq_timeout, 
 112		 "Timeout (in seconds) waiting for devices to answer INQUIRY."
 113		 " Default is 20. Some devices may need more; most need less.");
 114
 115/* This lock protects only this list */
 116static DEFINE_SPINLOCK(async_scan_lock);
 117static LIST_HEAD(scanning_hosts);
 118
 119struct async_scan_data {
 120	struct list_head list;
 121	struct Scsi_Host *shost;
 122	struct completion prev_finished;
 123};
 124
 125/**
 126 * scsi_complete_async_scans - Wait for asynchronous scans to complete
 127 *
 128 * When this function returns, any host which started scanning before
 129 * this function was called will have finished its scan.  Hosts which
 130 * started scanning after this function was called may or may not have
 131 * finished.
 132 */
 133int scsi_complete_async_scans(void)
 134{
 135	struct async_scan_data *data;
 136
 137	do {
 138		if (list_empty(&scanning_hosts))
 139			return 0;
 140		/* If we can't get memory immediately, that's OK.  Just
 141		 * sleep a little.  Even if we never get memory, the async
 142		 * scans will finish eventually.
 143		 */
 144		data = kmalloc(sizeof(*data), GFP_KERNEL);
 145		if (!data)
 146			msleep(1);
 147	} while (!data);
 148
 149	data->shost = NULL;
 150	init_completion(&data->prev_finished);
 151
 152	spin_lock(&async_scan_lock);
 153	/* Check that there's still somebody else on the list */
 154	if (list_empty(&scanning_hosts))
 155		goto done;
 156	list_add_tail(&data->list, &scanning_hosts);
 157	spin_unlock(&async_scan_lock);
 158
 159	printk(KERN_INFO "scsi: waiting for bus probes to complete ...\n");
 160	wait_for_completion(&data->prev_finished);
 161
 162	spin_lock(&async_scan_lock);
 163	list_del(&data->list);
 164	if (!list_empty(&scanning_hosts)) {
 165		struct async_scan_data *next = list_entry(scanning_hosts.next,
 166				struct async_scan_data, list);
 167		complete(&next->prev_finished);
 168	}
 169 done:
 170	spin_unlock(&async_scan_lock);
 171
 172	kfree(data);
 173	return 0;
 174}
 175
 176/**
 177 * scsi_unlock_floptical - unlock device via a special MODE SENSE command
 178 * @sdev:	scsi device to send command to
 179 * @result:	area to store the result of the MODE SENSE
 180 *
 181 * Description:
 182 *     Send a vendor specific MODE SENSE (not a MODE SELECT) command.
 183 *     Called for BLIST_KEY devices.
 184 **/
 185static void scsi_unlock_floptical(struct scsi_device *sdev,
 186				  unsigned char *result)
 187{
 188	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
 189
 190	sdev_printk(KERN_NOTICE, sdev, "unlocking floptical drive\n");
 191	scsi_cmd[0] = MODE_SENSE;
 192	scsi_cmd[1] = 0;
 193	scsi_cmd[2] = 0x2e;
 194	scsi_cmd[3] = 0;
 195	scsi_cmd[4] = 0x2a;     /* size */
 196	scsi_cmd[5] = 0;
 197	scsi_execute_req(sdev, scsi_cmd, DMA_FROM_DEVICE, result, 0x2a, NULL,
 198			 SCSI_TIMEOUT, 3, NULL);
 199}
 200
 201/**
 202 * scsi_alloc_sdev - allocate and setup a scsi_Device
 203 * @starget: which target to allocate a &scsi_device for
 204 * @lun: which lun
 205 * @hostdata: usually NULL and set by ->slave_alloc instead
 206 *
 207 * Description:
 208 *     Allocate, initialize for io, and return a pointer to a scsi_Device.
 209 *     Stores the @shost, @channel, @id, and @lun in the scsi_Device, and
 210 *     adds scsi_Device to the appropriate list.
 211 *
 212 * Return value:
 213 *     scsi_Device pointer, or NULL on failure.
 214 **/
 215static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
 216					   u64 lun, void *hostdata)
 217{
 218	struct scsi_device *sdev;
 219	int display_failure_msg = 1, ret;
 220	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 221
 222	sdev = kzalloc(sizeof(*sdev) + shost->transportt->device_size,
 223		       GFP_KERNEL);
 224	if (!sdev)
 225		goto out;
 226
 227	sdev->vendor = scsi_null_device_strs;
 228	sdev->model = scsi_null_device_strs;
 229	sdev->rev = scsi_null_device_strs;
 230	sdev->host = shost;
 231	sdev->queue_ramp_up_period = SCSI_DEFAULT_RAMP_UP_PERIOD;
 232	sdev->id = starget->id;
 233	sdev->lun = lun;
 234	sdev->channel = starget->channel;
 235	mutex_init(&sdev->state_mutex);
 236	sdev->sdev_state = SDEV_CREATED;
 237	INIT_LIST_HEAD(&sdev->siblings);
 238	INIT_LIST_HEAD(&sdev->same_target_siblings);
 
 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	sdev->request_queue = scsi_mq_alloc_queue(sdev);
 269	if (!sdev->request_queue) {
 270		/* release fn is set up in scsi_sysfs_device_initialise, so
 271		 * have to free and put manually here */
 272		put_device(&starget->dev);
 273		kfree(sdev);
 274		goto out;
 275	}
 276	WARN_ON_ONCE(!blk_get_queue(sdev->request_queue));
 277	sdev->request_queue->queuedata = sdev;
 278
 279	scsi_change_queue_depth(sdev, sdev->host->cmd_per_lun ?
 280					sdev->host->cmd_per_lun : 1);
 281
 282	scsi_sysfs_device_initialize(sdev);
 283
 284	if (shost->hostt->slave_alloc) {
 285		ret = shost->hostt->slave_alloc(sdev);
 286		if (ret) {
 287			/*
 288			 * if LLDD reports slave not present, don't clutter
 289			 * console with alloc failure messages
 290			 */
 291			if (ret == -ENXIO)
 292				display_failure_msg = 0;
 293			goto out_device_destroy;
 294		}
 295	}
 296
 297	return sdev;
 298
 299out_device_destroy:
 300	__scsi_remove_device(sdev);
 301out:
 302	if (display_failure_msg)
 303		printk(ALLOC_FAILURE_MSG, __func__);
 304	return NULL;
 305}
 306
 307static void scsi_target_destroy(struct scsi_target *starget)
 308{
 309	struct device *dev = &starget->dev;
 310	struct Scsi_Host *shost = dev_to_shost(dev->parent);
 311	unsigned long flags;
 312
 313	BUG_ON(starget->state == STARGET_DEL);
 314	starget->state = STARGET_DEL;
 315	transport_destroy_device(dev);
 316	spin_lock_irqsave(shost->host_lock, flags);
 317	if (shost->hostt->target_destroy)
 318		shost->hostt->target_destroy(starget);
 319	list_del_init(&starget->siblings);
 320	spin_unlock_irqrestore(shost->host_lock, flags);
 321	put_device(dev);
 322}
 323
 324static void scsi_target_dev_release(struct device *dev)
 325{
 326	struct device *parent = dev->parent;
 327	struct scsi_target *starget = to_scsi_target(dev);
 328
 329	kfree(starget);
 330	put_device(parent);
 331}
 332
 333static struct device_type scsi_target_type = {
 334	.name =		"scsi_target",
 335	.release =	scsi_target_dev_release,
 336};
 337
 338int scsi_is_target_device(const struct device *dev)
 339{
 340	return dev->type == &scsi_target_type;
 341}
 342EXPORT_SYMBOL(scsi_is_target_device);
 343
 344static struct scsi_target *__scsi_find_target(struct device *parent,
 345					      int channel, uint id)
 346{
 347	struct scsi_target *starget, *found_starget = NULL;
 348	struct Scsi_Host *shost = dev_to_shost(parent);
 349	/*
 350	 * Search for an existing target for this sdev.
 351	 */
 352	list_for_each_entry(starget, &shost->__targets, siblings) {
 353		if (starget->id == id &&
 354		    starget->channel == channel) {
 355			found_starget = starget;
 356			break;
 357		}
 358	}
 359	if (found_starget)
 360		get_device(&found_starget->dev);
 361
 362	return found_starget;
 363}
 364
 365/**
 366 * scsi_target_reap_ref_release - remove target from visibility
 367 * @kref: the reap_ref in the target being released
 368 *
 369 * Called on last put of reap_ref, which is the indication that no device
 370 * under this target is visible anymore, so render the target invisible in
 371 * sysfs.  Note: we have to be in user context here because the target reaps
 372 * should be done in places where the scsi device visibility is being removed.
 373 */
 374static void scsi_target_reap_ref_release(struct kref *kref)
 375{
 376	struct scsi_target *starget
 377		= container_of(kref, struct scsi_target, reap_ref);
 378
 379	/*
 380	 * if we get here and the target is still in a CREATED state that
 381	 * means it was allocated but never made visible (because a scan
 382	 * turned up no LUNs), so don't call device_del() on it.
 383	 */
 384	if ((starget->state != STARGET_CREATED) &&
 385	    (starget->state != STARGET_CREATED_REMOVE)) {
 386		transport_remove_device(&starget->dev);
 387		device_del(&starget->dev);
 388	}
 389	scsi_target_destroy(starget);
 390}
 391
 392static void scsi_target_reap_ref_put(struct scsi_target *starget)
 393{
 394	kref_put(&starget->reap_ref, scsi_target_reap_ref_release);
 395}
 396
 397/**
 398 * scsi_alloc_target - allocate a new or find an existing target
 399 * @parent:	parent of the target (need not be a scsi host)
 400 * @channel:	target channel number (zero if no channels)
 401 * @id:		target id number
 402 *
 403 * Return an existing target if one exists, provided it hasn't already
 404 * gone into STARGET_DEL state, otherwise allocate a new target.
 405 *
 406 * The target is returned with an incremented reference, so the caller
 407 * is responsible for both reaping and doing a last put
 408 */
 409static struct scsi_target *scsi_alloc_target(struct device *parent,
 410					     int channel, uint id)
 411{
 412	struct Scsi_Host *shost = dev_to_shost(parent);
 413	struct device *dev = NULL;
 414	unsigned long flags;
 415	const int size = sizeof(struct scsi_target)
 416		+ shost->transportt->target_size;
 417	struct scsi_target *starget;
 418	struct scsi_target *found_target;
 419	int error, ref_got;
 420
 421	starget = kzalloc(size, GFP_KERNEL);
 422	if (!starget) {
 423		printk(KERN_ERR "%s: allocation failure\n", __func__);
 424		return NULL;
 425	}
 426	dev = &starget->dev;
 427	device_initialize(dev);
 428	kref_init(&starget->reap_ref);
 429	dev->parent = get_device(parent);
 430	dev_set_name(dev, "target%d:%d:%d", shost->host_no, channel, id);
 431	dev->bus = &scsi_bus_type;
 432	dev->type = &scsi_target_type;
 433	starget->id = id;
 434	starget->channel = channel;
 435	starget->can_queue = 0;
 436	INIT_LIST_HEAD(&starget->siblings);
 437	INIT_LIST_HEAD(&starget->devices);
 438	starget->state = STARGET_CREATED;
 439	starget->scsi_level = SCSI_2;
 440	starget->max_target_blocked = SCSI_DEFAULT_TARGET_BLOCKED;
 441 retry:
 442	spin_lock_irqsave(shost->host_lock, flags);
 443
 444	found_target = __scsi_find_target(parent, channel, id);
 445	if (found_target)
 446		goto found;
 447
 448	list_add_tail(&starget->siblings, &shost->__targets);
 449	spin_unlock_irqrestore(shost->host_lock, flags);
 450	/* allocate and add */
 451	transport_setup_device(dev);
 452	if (shost->hostt->target_alloc) {
 453		error = shost->hostt->target_alloc(starget);
 454
 455		if(error) {
 456			dev_printk(KERN_ERR, dev, "target allocation failed, error %d\n", error);
 457			/* don't want scsi_target_reap to do the final
 458			 * put because it will be under the host lock */
 459			scsi_target_destroy(starget);
 460			return NULL;
 461		}
 462	}
 463	get_device(dev);
 464
 465	return starget;
 466
 467 found:
 468	/*
 469	 * release routine already fired if kref is zero, so if we can still
 470	 * take the reference, the target must be alive.  If we can't, it must
 471	 * be dying and we need to wait for a new target
 472	 */
 473	ref_got = kref_get_unless_zero(&found_target->reap_ref);
 474
 475	spin_unlock_irqrestore(shost->host_lock, flags);
 476	if (ref_got) {
 477		put_device(dev);
 478		return found_target;
 479	}
 480	/*
 481	 * Unfortunately, we found a dying target; need to wait until it's
 482	 * dead before we can get a new one.  There is an anomaly here.  We
 483	 * *should* call scsi_target_reap() to balance the kref_get() of the
 484	 * reap_ref above.  However, since the target being released, it's
 485	 * already invisible and the reap_ref is irrelevant.  If we call
 486	 * scsi_target_reap() we might spuriously do another device_del() on
 487	 * an already invisible target.
 488	 */
 489	put_device(&found_target->dev);
 490	/*
 491	 * length of time is irrelevant here, we just want to yield the CPU
 492	 * for a tick to avoid busy waiting for the target to die.
 493	 */
 494	msleep(1);
 495	goto retry;
 496}
 497
 498/**
 499 * scsi_target_reap - check to see if target is in use and destroy if not
 500 * @starget: target to be checked
 501 *
 502 * This is used after removing a LUN or doing a last put of the target
 503 * it checks atomically that nothing is using the target and removes
 504 * it if so.
 505 */
 506void scsi_target_reap(struct scsi_target *starget)
 507{
 508	/*
 509	 * serious problem if this triggers: STARGET_DEL is only set in the if
 510	 * the reap_ref drops to zero, so we're trying to do another final put
 511	 * on an already released kref
 512	 */
 513	BUG_ON(starget->state == STARGET_DEL);
 514	scsi_target_reap_ref_put(starget);
 515}
 516
 517/**
 518 * scsi_sanitize_inquiry_string - remove non-graphical chars from an
 519 *                                INQUIRY result string
 520 * @s: INQUIRY result string to sanitize
 521 * @len: length of the string
 522 *
 523 * Description:
 524 *	The SCSI spec says that INQUIRY vendor, product, and revision
 525 *	strings must consist entirely of graphic ASCII characters,
 526 *	padded on the right with spaces.  Since not all devices obey
 527 *	this rule, we will replace non-graphic or non-ASCII characters
 528 *	with spaces.  Exception: a NUL character is interpreted as a
 529 *	string terminator, so all the following characters are set to
 530 *	spaces.
 531 **/
 532void scsi_sanitize_inquiry_string(unsigned char *s, int len)
 533{
 534	int terminated = 0;
 535
 536	for (; len > 0; (--len, ++s)) {
 537		if (*s == 0)
 538			terminated = 1;
 539		if (terminated || *s < 0x20 || *s > 0x7e)
 540			*s = ' ';
 541	}
 542}
 543EXPORT_SYMBOL(scsi_sanitize_inquiry_string);
 544
 545/**
 546 * scsi_probe_lun - probe a single LUN using a SCSI INQUIRY
 547 * @sdev:	scsi_device to probe
 548 * @inq_result:	area to store the INQUIRY result
 549 * @result_len: len of inq_result
 550 * @bflags:	store any bflags found here
 551 *
 552 * Description:
 553 *     Probe the lun associated with @req using a standard SCSI INQUIRY;
 554 *
 555 *     If the INQUIRY is successful, zero is returned and the
 556 *     INQUIRY data is in @inq_result; the scsi_level and INQUIRY length
 557 *     are copied to the scsi_device any flags value is stored in *@bflags.
 558 **/
 559static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result,
 560			  int result_len, blist_flags_t *bflags)
 561{
 562	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
 563	int first_inquiry_len, try_inquiry_len, next_inquiry_len;
 564	int response_len = 0;
 565	int pass, count, result;
 566	struct scsi_sense_hdr sshdr;
 567
 568	*bflags = 0;
 569
 570	/* Perform up to 3 passes.  The first pass uses a conservative
 571	 * transfer length of 36 unless sdev->inquiry_len specifies a
 572	 * different value. */
 573	first_inquiry_len = sdev->inquiry_len ? sdev->inquiry_len : 36;
 574	try_inquiry_len = first_inquiry_len;
 575	pass = 1;
 576
 577 next_pass:
 578	SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
 579				"scsi scan: INQUIRY pass %d length %d\n",
 580				pass, try_inquiry_len));
 581
 582	/* Each pass gets up to three chances to ignore Unit Attention */
 583	for (count = 0; count < 3; ++count) {
 584		int resid;
 585
 586		memset(scsi_cmd, 0, 6);
 587		scsi_cmd[0] = INQUIRY;
 588		scsi_cmd[4] = (unsigned char) try_inquiry_len;
 589
 590		memset(inq_result, 0, try_inquiry_len);
 591
 592		result = scsi_execute_req(sdev,  scsi_cmd, DMA_FROM_DEVICE,
 593					  inq_result, try_inquiry_len, &sshdr,
 594					  HZ / 2 + HZ * scsi_inq_timeout, 3,
 595					  &resid);
 596
 597		SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
 598				"scsi scan: INQUIRY %s with code 0x%x\n",
 599				result ? "failed" : "successful", result));
 600
 601		if (result) {
 602			/*
 603			 * not-ready to ready transition [asc/ascq=0x28/0x0]
 604			 * or power-on, reset [asc/ascq=0x29/0x0], continue.
 605			 * INQUIRY should not yield UNIT_ATTENTION
 606			 * but many buggy devices do so anyway. 
 607			 */
 608			if (driver_byte(result) == DRIVER_SENSE &&
 609			    scsi_sense_valid(&sshdr)) {
 610				if ((sshdr.sense_key == UNIT_ATTENTION) &&
 611				    ((sshdr.asc == 0x28) ||
 612				     (sshdr.asc == 0x29)) &&
 613				    (sshdr.ascq == 0))
 614					continue;
 615			}
 616		} else {
 617			/*
 618			 * if nothing was transferred, we try
 619			 * again. It's a workaround for some USB
 620			 * devices.
 621			 */
 622			if (resid == try_inquiry_len)
 623				continue;
 624		}
 625		break;
 626	}
 627
 628	if (result == 0) {
 629		scsi_sanitize_inquiry_string(&inq_result[8], 8);
 630		scsi_sanitize_inquiry_string(&inq_result[16], 16);
 631		scsi_sanitize_inquiry_string(&inq_result[32], 4);
 632
 633		response_len = inq_result[4] + 5;
 634		if (response_len > 255)
 635			response_len = first_inquiry_len;	/* sanity */
 636
 637		/*
 638		 * Get any flags for this device.
 639		 *
 640		 * XXX add a bflags to scsi_device, and replace the
 641		 * corresponding bit fields in scsi_device, so bflags
 642		 * need not be passed as an argument.
 643		 */
 644		*bflags = scsi_get_device_flags(sdev, &inq_result[8],
 645				&inq_result[16]);
 646
 647		/* When the first pass succeeds we gain information about
 648		 * what larger transfer lengths might work. */
 649		if (pass == 1) {
 650			if (BLIST_INQUIRY_36 & *bflags)
 651				next_inquiry_len = 36;
 652			else if (sdev->inquiry_len)
 653				next_inquiry_len = sdev->inquiry_len;
 654			else
 655				next_inquiry_len = response_len;
 656
 657			/* If more data is available perform the second pass */
 658			if (next_inquiry_len > try_inquiry_len) {
 659				try_inquiry_len = next_inquiry_len;
 660				pass = 2;
 661				goto next_pass;
 662			}
 663		}
 664
 665	} else if (pass == 2) {
 666		sdev_printk(KERN_INFO, sdev,
 667			    "scsi scan: %d byte inquiry failed.  "
 668			    "Consider BLIST_INQUIRY_36 for this device\n",
 669			    try_inquiry_len);
 670
 671		/* If this pass failed, the third pass goes back and transfers
 672		 * the same amount as we successfully got in the first pass. */
 673		try_inquiry_len = first_inquiry_len;
 674		pass = 3;
 675		goto next_pass;
 676	}
 677
 678	/* If the last transfer attempt got an error, assume the
 679	 * peripheral doesn't exist or is dead. */
 680	if (result)
 681		return -EIO;
 682
 683	/* Don't report any more data than the device says is valid */
 684	sdev->inquiry_len = min(try_inquiry_len, response_len);
 685
 686	/*
 687	 * XXX Abort if the response length is less than 36? If less than
 688	 * 32, the lookup of the device flags (above) could be invalid,
 689	 * and it would be possible to take an incorrect action - we do
 690	 * not want to hang because of a short INQUIRY. On the flip side,
 691	 * if the device is spun down or becoming ready (and so it gives a
 692	 * short INQUIRY), an abort here prevents any further use of the
 693	 * device, including spin up.
 694	 *
 695	 * On the whole, the best approach seems to be to assume the first
 696	 * 36 bytes are valid no matter what the device says.  That's
 697	 * better than copying < 36 bytes to the inquiry-result buffer
 698	 * and displaying garbage for the Vendor, Product, or Revision
 699	 * strings.
 700	 */
 701	if (sdev->inquiry_len < 36) {
 702		if (!sdev->host->short_inquiry) {
 703			shost_printk(KERN_INFO, sdev->host,
 704				    "scsi scan: INQUIRY result too short (%d),"
 705				    " using 36\n", sdev->inquiry_len);
 706			sdev->host->short_inquiry = 1;
 707		}
 708		sdev->inquiry_len = 36;
 709	}
 710
 711	/*
 712	 * Related to the above issue:
 713	 *
 714	 * XXX Devices (disk or all?) should be sent a TEST UNIT READY,
 715	 * and if not ready, sent a START_STOP to start (maybe spin up) and
 716	 * then send the INQUIRY again, since the INQUIRY can change after
 717	 * a device is initialized.
 718	 *
 719	 * Ideally, start a device if explicitly asked to do so.  This
 720	 * assumes that a device is spun up on power on, spun down on
 721	 * request, and then spun up on request.
 722	 */
 723
 724	/*
 725	 * The scanning code needs to know the scsi_level, even if no
 726	 * device is attached at LUN 0 (SCSI_SCAN_TARGET_PRESENT) so
 727	 * non-zero LUNs can be scanned.
 728	 */
 729	sdev->scsi_level = inq_result[2] & 0x07;
 730	if (sdev->scsi_level >= 2 ||
 731	    (sdev->scsi_level == 1 && (inq_result[3] & 0x0f) == 1))
 732		sdev->scsi_level++;
 733	sdev->sdev_target->scsi_level = sdev->scsi_level;
 734
 735	/*
 736	 * If SCSI-2 or lower, and if the transport requires it,
 737	 * store the LUN value in CDB[1].
 738	 */
 739	sdev->lun_in_cdb = 0;
 740	if (sdev->scsi_level <= SCSI_2 &&
 741	    sdev->scsi_level != SCSI_UNKNOWN &&
 742	    !sdev->host->no_scsi2_lun_in_cdb)
 743		sdev->lun_in_cdb = 1;
 744
 745	return 0;
 746}
 747
 748/**
 749 * scsi_add_lun - allocate and fully initialze a scsi_device
 750 * @sdev:	holds information to be stored in the new scsi_device
 751 * @inq_result:	holds the result of a previous INQUIRY to the LUN
 752 * @bflags:	black/white list flag
 753 * @async:	1 if this device is being scanned asynchronously
 754 *
 755 * Description:
 756 *     Initialize the scsi_device @sdev.  Optionally set fields based
 757 *     on values in *@bflags.
 758 *
 759 * Return:
 760 *     SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
 761 *     SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
 762 **/
 763static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 764		blist_flags_t *bflags, int async)
 765{
 766	int ret;
 767
 768	/*
 769	 * XXX do not save the inquiry, since it can change underneath us,
 770	 * save just vendor/model/rev.
 771	 *
 772	 * Rather than save it and have an ioctl that retrieves the saved
 773	 * value, have an ioctl that executes the same INQUIRY code used
 774	 * in scsi_probe_lun, let user level programs doing INQUIRY
 775	 * scanning run at their own risk, or supply a user level program
 776	 * that can correctly scan.
 777	 */
 778
 779	/*
 780	 * Copy at least 36 bytes of INQUIRY data, so that we don't
 781	 * dereference unallocated memory when accessing the Vendor,
 782	 * Product, and Revision strings.  Badly behaved devices may set
 783	 * the INQUIRY Additional Length byte to a small value, indicating
 784	 * these strings are invalid, but often they contain plausible data
 785	 * nonetheless.  It doesn't matter if the device sent < 36 bytes
 786	 * total, since scsi_probe_lun() initializes inq_result with 0s.
 787	 */
 788	sdev->inquiry = kmemdup(inq_result,
 789				max_t(size_t, sdev->inquiry_len, 36),
 790				GFP_KERNEL);
 791	if (sdev->inquiry == NULL)
 792		return SCSI_SCAN_NO_RESPONSE;
 793
 794	sdev->vendor = (char *) (sdev->inquiry + 8);
 795	sdev->model = (char *) (sdev->inquiry + 16);
 796	sdev->rev = (char *) (sdev->inquiry + 32);
 797
 798	if (strncmp(sdev->vendor, "ATA     ", 8) == 0) {
 799		/*
 800		 * sata emulation layer device.  This is a hack to work around
 801		 * the SATL power management specifications which state that
 802		 * when the SATL detects the device has gone into standby
 803		 * mode, it shall respond with NOT READY.
 804		 */
 805		sdev->allow_restart = 1;
 806	}
 807
 808	if (*bflags & BLIST_ISROM) {
 809		sdev->type = TYPE_ROM;
 810		sdev->removable = 1;
 811	} else {
 812		sdev->type = (inq_result[0] & 0x1f);
 813		sdev->removable = (inq_result[1] & 0x80) >> 7;
 814
 815		/*
 816		 * some devices may respond with wrong type for
 817		 * well-known logical units. Force well-known type
 818		 * to enumerate them correctly.
 819		 */
 820		if (scsi_is_wlun(sdev->lun) && sdev->type != TYPE_WLUN) {
 821			sdev_printk(KERN_WARNING, sdev,
 822				"%s: correcting incorrect peripheral device type 0x%x for W-LUN 0x%16xhN\n",
 823				__func__, sdev->type, (unsigned int)sdev->lun);
 824			sdev->type = TYPE_WLUN;
 825		}
 826
 827	}
 828
 829	if (sdev->type == TYPE_RBC || sdev->type == TYPE_ROM) {
 830		/* RBC and MMC devices can return SCSI-3 compliance and yet
 831		 * still not support REPORT LUNS, so make them act as
 832		 * BLIST_NOREPORTLUN unless BLIST_REPORTLUN2 is
 833		 * specifically set */
 834		if ((*bflags & BLIST_REPORTLUN2) == 0)
 835			*bflags |= BLIST_NOREPORTLUN;
 836	}
 837
 838	/*
 839	 * For a peripheral qualifier (PQ) value of 1 (001b), the SCSI
 840	 * spec says: The device server is capable of supporting the
 841	 * specified peripheral device type on this logical unit. However,
 842	 * the physical device is not currently connected to this logical
 843	 * unit.
 844	 *
 845	 * The above is vague, as it implies that we could treat 001 and
 846	 * 011 the same. Stay compatible with previous code, and create a
 847	 * scsi_device for a PQ of 1
 848	 *
 849	 * Don't set the device offline here; rather let the upper
 850	 * level drivers eval the PQ to decide whether they should
 851	 * attach. So remove ((inq_result[0] >> 5) & 7) == 1 check.
 852	 */ 
 853
 854	sdev->inq_periph_qual = (inq_result[0] >> 5) & 7;
 855	sdev->lockable = sdev->removable;
 856	sdev->soft_reset = (inq_result[7] & 1) && ((inq_result[3] & 7) == 2);
 857
 858	if (sdev->scsi_level >= SCSI_3 ||
 859			(sdev->inquiry_len > 56 && inq_result[56] & 0x04))
 860		sdev->ppr = 1;
 861	if (inq_result[7] & 0x60)
 862		sdev->wdtr = 1;
 863	if (inq_result[7] & 0x10)
 864		sdev->sdtr = 1;
 865
 866	sdev_printk(KERN_NOTICE, sdev, "%s %.8s %.16s %.4s PQ: %d "
 867			"ANSI: %d%s\n", scsi_device_type(sdev->type),
 868			sdev->vendor, sdev->model, sdev->rev,
 869			sdev->inq_periph_qual, inq_result[2] & 0x07,
 870			(inq_result[3] & 0x0f) == 1 ? " CCS" : "");
 871
 872	if ((sdev->scsi_level >= SCSI_2) && (inq_result[7] & 2) &&
 873	    !(*bflags & BLIST_NOTQ)) {
 874		sdev->tagged_supported = 1;
 875		sdev->simple_tags = 1;
 876	}
 877
 878	/*
 879	 * Some devices (Texel CD ROM drives) have handshaking problems
 880	 * when used with the Seagate controllers. borken is initialized
 881	 * to 1, and then set it to 0 here.
 882	 */
 883	if ((*bflags & BLIST_BORKEN) == 0)
 884		sdev->borken = 0;
 885
 886	if (*bflags & BLIST_NO_ULD_ATTACH)
 887		sdev->no_uld_attach = 1;
 888
 889	/*
 890	 * Apparently some really broken devices (contrary to the SCSI
 891	 * standards) need to be selected without asserting ATN
 892	 */
 893	if (*bflags & BLIST_SELECT_NO_ATN)
 894		sdev->select_no_atn = 1;
 895
 896	/*
 897	 * Maximum 512 sector transfer length
 898	 * broken RA4x00 Compaq Disk Array
 899	 */
 900	if (*bflags & BLIST_MAX_512)
 901		blk_queue_max_hw_sectors(sdev->request_queue, 512);
 902	/*
 903	 * Max 1024 sector transfer length for targets that report incorrect
 904	 * max/optimal lengths and relied on the old block layer safe default
 905	 */
 906	else if (*bflags & BLIST_MAX_1024)
 907		blk_queue_max_hw_sectors(sdev->request_queue, 1024);
 908
 909	/*
 910	 * Some devices may not want to have a start command automatically
 911	 * issued when a device is added.
 912	 */
 913	if (*bflags & BLIST_NOSTARTONADD)
 914		sdev->no_start_on_add = 1;
 915
 916	if (*bflags & BLIST_SINGLELUN)
 917		scsi_target(sdev)->single_lun = 1;
 918
 919	sdev->use_10_for_rw = 1;
 920
 921	/* some devices don't like REPORT SUPPORTED OPERATION CODES
 922	 * and will simply timeout causing sd_mod init to take a very
 923	 * very long time */
 924	if (*bflags & BLIST_NO_RSOC)
 925		sdev->no_report_opcodes = 1;
 926
 927	/* set the device running here so that slave configure
 928	 * may do I/O */
 929	mutex_lock(&sdev->state_mutex);
 930	ret = scsi_device_set_state(sdev, SDEV_RUNNING);
 931	if (ret)
 932		ret = scsi_device_set_state(sdev, SDEV_BLOCK);
 933	mutex_unlock(&sdev->state_mutex);
 934
 935	if (ret) {
 936		sdev_printk(KERN_ERR, sdev,
 937			    "in wrong state %s to complete scan\n",
 938			    scsi_device_state_name(sdev->sdev_state));
 939		return SCSI_SCAN_NO_RESPONSE;
 940	}
 941
 942	if (*bflags & BLIST_NOT_LOCKABLE)
 943		sdev->lockable = 0;
 944
 945	if (*bflags & BLIST_RETRY_HWERROR)
 946		sdev->retry_hwerror = 1;
 947
 948	if (*bflags & BLIST_NO_DIF)
 949		sdev->no_dif = 1;
 950
 951	if (*bflags & BLIST_UNMAP_LIMIT_WS)
 952		sdev->unmap_limit_for_ws = 1;
 953
 954	sdev->eh_timeout = SCSI_DEFAULT_EH_TIMEOUT;
 955
 956	if (*bflags & BLIST_TRY_VPD_PAGES)
 957		sdev->try_vpd_pages = 1;
 958	else if (*bflags & BLIST_SKIP_VPD_PAGES)
 959		sdev->skip_vpd_pages = 1;
 960
 961	transport_configure_device(&sdev->sdev_gendev);
 962
 963	if (sdev->host->hostt->slave_configure) {
 964		ret = sdev->host->hostt->slave_configure(sdev);
 965		if (ret) {
 966			/*
 967			 * if LLDD reports slave not present, don't clutter
 968			 * console with alloc failure messages
 969			 */
 970			if (ret != -ENXIO) {
 971				sdev_printk(KERN_ERR, sdev,
 972					"failed to configure device\n");
 973			}
 974			return SCSI_SCAN_NO_RESPONSE;
 975		}
 976	}
 977
 978	if (sdev->scsi_level >= SCSI_3)
 979		scsi_attach_vpd(sdev);
 980
 981	sdev->max_queue_depth = sdev->queue_depth;
 982	sdev->sdev_bflags = *bflags;
 983
 984	/*
 985	 * Ok, the device is now all set up, we can
 986	 * register it and tell the rest of the kernel
 987	 * about it.
 988	 */
 989	if (!async && scsi_sysfs_add_sdev(sdev) != 0)
 990		return SCSI_SCAN_NO_RESPONSE;
 991
 992	return SCSI_SCAN_LUN_PRESENT;
 993}
 994
 995#ifdef CONFIG_SCSI_LOGGING
 996/** 
 997 * scsi_inq_str - print INQUIRY data from min to max index, strip trailing whitespace
 998 * @buf:   Output buffer with at least end-first+1 bytes of space
 999 * @inq:   Inquiry buffer (input)
1000 * @first: Offset of string into inq
1001 * @end:   Index after last character in inq
1002 */
1003static unsigned char *scsi_inq_str(unsigned char *buf, unsigned char *inq,
1004				   unsigned first, unsigned end)
1005{
1006	unsigned term = 0, idx;
1007
1008	for (idx = 0; idx + first < end && idx + first < inq[4] + 5; idx++) {
1009		if (inq[idx+first] > ' ') {
1010			buf[idx] = inq[idx+first];
1011			term = idx+1;
1012		} else {
1013			buf[idx] = ' ';
1014		}
1015	}
1016	buf[term] = 0;
1017	return buf;
1018}
1019#endif
1020
1021/**
1022 * scsi_probe_and_add_lun - probe a LUN, if a LUN is found add it
1023 * @starget:	pointer to target device structure
1024 * @lun:	LUN of target device
1025 * @bflagsp:	store bflags here if not NULL
1026 * @sdevp:	probe the LUN corresponding to this scsi_device
1027 * @rescan:     if not equal to SCSI_SCAN_INITIAL skip some code only
1028 *              needed on first scan
1029 * @hostdata:	passed to scsi_alloc_sdev()
1030 *
1031 * Description:
1032 *     Call scsi_probe_lun, if a LUN with an attached device is found,
1033 *     allocate and set it up by calling scsi_add_lun.
1034 *
1035 * Return:
1036 *
1037 *   - SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
1038 *   - SCSI_SCAN_TARGET_PRESENT: target responded, but no device is
1039 *         attached at the LUN
1040 *   - SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
1041 **/
1042static int scsi_probe_and_add_lun(struct scsi_target *starget,
1043				  u64 lun, blist_flags_t *bflagsp,
1044				  struct scsi_device **sdevp,
1045				  enum scsi_scan_mode rescan,
1046				  void *hostdata)
1047{
1048	struct scsi_device *sdev;
1049	unsigned char *result;
1050	blist_flags_t bflags;
1051	int res = SCSI_SCAN_NO_RESPONSE, result_len = 256;
1052	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1053
1054	/*
1055	 * The rescan flag is used as an optimization, the first scan of a
1056	 * host adapter calls into here with rescan == 0.
1057	 */
1058	sdev = scsi_device_lookup_by_target(starget, lun);
1059	if (sdev) {
1060		if (rescan != SCSI_SCAN_INITIAL || !scsi_device_created(sdev)) {
1061			SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
1062				"scsi scan: device exists on %s\n",
1063				dev_name(&sdev->sdev_gendev)));
1064			if (sdevp)
1065				*sdevp = sdev;
1066			else
1067				scsi_device_put(sdev);
1068
1069			if (bflagsp)
1070				*bflagsp = scsi_get_device_flags(sdev,
1071								 sdev->vendor,
1072								 sdev->model);
1073			return SCSI_SCAN_LUN_PRESENT;
1074		}
1075		scsi_device_put(sdev);
1076	} else
1077		sdev = scsi_alloc_sdev(starget, lun, hostdata);
1078	if (!sdev)
1079		goto out;
1080
1081	result = kmalloc(result_len, GFP_KERNEL |
1082			((shost->unchecked_isa_dma) ? __GFP_DMA : 0));
1083	if (!result)
1084		goto out_free_sdev;
1085
1086	if (scsi_probe_lun(sdev, result, result_len, &bflags))
1087		goto out_free_result;
1088
1089	if (bflagsp)
1090		*bflagsp = bflags;
1091	/*
1092	 * result contains valid SCSI INQUIRY data.
1093	 */
1094	if ((result[0] >> 5) == 3) {
1095		/*
1096		 * For a Peripheral qualifier 3 (011b), the SCSI
1097		 * spec says: The device server is not capable of
1098		 * supporting a physical device on this logical
1099		 * unit.
1100		 *
1101		 * For disks, this implies that there is no
1102		 * logical disk configured at sdev->lun, but there
1103		 * is a target id responding.
1104		 */
1105		SCSI_LOG_SCAN_BUS(2, sdev_printk(KERN_INFO, sdev, "scsi scan:"
1106				   " peripheral qualifier of 3, device not"
1107				   " added\n"))
1108		if (lun == 0) {
1109			SCSI_LOG_SCAN_BUS(1, {
1110				unsigned char vend[9];
1111				unsigned char mod[17];
1112
1113				sdev_printk(KERN_INFO, sdev,
1114					"scsi scan: consider passing scsi_mod."
1115					"dev_flags=%s:%s:0x240 or 0x1000240\n",
1116					scsi_inq_str(vend, result, 8, 16),
1117					scsi_inq_str(mod, result, 16, 32));
1118			});
1119
1120		}
1121
1122		res = SCSI_SCAN_TARGET_PRESENT;
1123		goto out_free_result;
1124	}
1125
1126	/*
1127	 * Some targets may set slight variations of PQ and PDT to signal
1128	 * that no LUN is present, so don't add sdev in these cases.
1129	 * Two specific examples are:
1130	 * 1) NetApp targets: return PQ=1, PDT=0x1f
1131	 * 2) IBM/2145 targets: return PQ=1, PDT=0
1132	 * 3) USB UFI: returns PDT=0x1f, with the PQ bits being "reserved"
1133	 *    in the UFI 1.0 spec (we cannot rely on reserved bits).
1134	 *
1135	 * References:
1136	 * 1) SCSI SPC-3, pp. 145-146
1137	 * PQ=1: "A peripheral device having the specified peripheral
1138	 * device type is not connected to this logical unit. However, the
1139	 * device server is capable of supporting the specified peripheral
1140	 * device type on this logical unit."
1141	 * PDT=0x1f: "Unknown or no device type"
1142	 * 2) USB UFI 1.0, p. 20
1143	 * PDT=00h Direct-access device (floppy)
1144	 * PDT=1Fh none (no FDD connected to the requested logical unit)
1145	 */
1146	if (((result[0] >> 5) == 1 ||
1147	    (starget->pdt_1f_for_no_lun && (result[0] & 0x1f) == 0x1f)) &&
1148	    !scsi_is_wlun(lun)) {
1149		SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
1150					"scsi scan: peripheral device type"
1151					" of 31, no device added\n"));
1152		res = SCSI_SCAN_TARGET_PRESENT;
1153		goto out_free_result;
1154	}
1155
1156	res = scsi_add_lun(sdev, result, &bflags, shost->async_scan);
1157	if (res == SCSI_SCAN_LUN_PRESENT) {
1158		if (bflags & BLIST_KEY) {
1159			sdev->lockable = 0;
1160			scsi_unlock_floptical(sdev, result);
1161		}
1162	}
1163
1164 out_free_result:
1165	kfree(result);
1166 out_free_sdev:
1167	if (res == SCSI_SCAN_LUN_PRESENT) {
1168		if (sdevp) {
1169			if (scsi_device_get(sdev) == 0) {
1170				*sdevp = sdev;
1171			} else {
1172				__scsi_remove_device(sdev);
1173				res = SCSI_SCAN_NO_RESPONSE;
1174			}
1175		}
1176	} else
1177		__scsi_remove_device(sdev);
1178 out:
1179	return res;
1180}
1181
1182/**
1183 * scsi_sequential_lun_scan - sequentially scan a SCSI target
1184 * @starget:	pointer to target structure to scan
1185 * @bflags:	black/white list flag for LUN 0
1186 * @scsi_level: Which version of the standard does this device adhere to
1187 * @rescan:     passed to scsi_probe_add_lun()
1188 *
1189 * Description:
1190 *     Generally, scan from LUN 1 (LUN 0 is assumed to already have been
1191 *     scanned) to some maximum lun until a LUN is found with no device
1192 *     attached. Use the bflags to figure out any oddities.
1193 *
1194 *     Modifies sdevscan->lun.
1195 **/
1196static void scsi_sequential_lun_scan(struct scsi_target *starget,
1197				     blist_flags_t bflags, int scsi_level,
1198				     enum scsi_scan_mode rescan)
1199{
1200	uint max_dev_lun;
1201	u64 sparse_lun, lun;
1202	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1203
1204	SCSI_LOG_SCAN_BUS(3, starget_printk(KERN_INFO, starget,
1205		"scsi scan: Sequential scan\n"));
1206
1207	max_dev_lun = min(max_scsi_luns, shost->max_lun);
1208	/*
1209	 * If this device is known to support sparse multiple units,
1210	 * override the other settings, and scan all of them. Normally,
1211	 * SCSI-3 devices should be scanned via the REPORT LUNS.
1212	 */
1213	if (bflags & BLIST_SPARSELUN) {
1214		max_dev_lun = shost->max_lun;
1215		sparse_lun = 1;
1216	} else
1217		sparse_lun = 0;
1218
1219	/*
1220	 * If less than SCSI_1_CCS, and no special lun scanning, stop
1221	 * scanning; this matches 2.4 behaviour, but could just be a bug
1222	 * (to continue scanning a SCSI_1_CCS device).
1223	 *
1224	 * This test is broken.  We might not have any device on lun0 for
1225	 * a sparselun device, and if that's the case then how would we
1226	 * know the real scsi_level, eh?  It might make sense to just not
1227	 * scan any SCSI_1 device for non-0 luns, but that check would best
1228	 * go into scsi_alloc_sdev() and just have it return null when asked
1229	 * to alloc an sdev for lun > 0 on an already found SCSI_1 device.
1230	 *
1231	if ((sdevscan->scsi_level < SCSI_1_CCS) &&
1232	    ((bflags & (BLIST_FORCELUN | BLIST_SPARSELUN | BLIST_MAX5LUN))
1233	     == 0))
1234		return;
1235	 */
1236	/*
1237	 * If this device is known to support multiple units, override
1238	 * the other settings, and scan all of them.
1239	 */
1240	if (bflags & BLIST_FORCELUN)
1241		max_dev_lun = shost->max_lun;
1242	/*
1243	 * REGAL CDC-4X: avoid hang after LUN 4
1244	 */
1245	if (bflags & BLIST_MAX5LUN)
1246		max_dev_lun = min(5U, max_dev_lun);
1247	/*
1248	 * Do not scan SCSI-2 or lower device past LUN 7, unless
1249	 * BLIST_LARGELUN.
1250	 */
1251	if (scsi_level < SCSI_3 && !(bflags & BLIST_LARGELUN))
1252		max_dev_lun = min(8U, max_dev_lun);
1253	else
1254		max_dev_lun = min(256U, max_dev_lun);
1255
1256	/*
1257	 * We have already scanned LUN 0, so start at LUN 1. Keep scanning
1258	 * until we reach the max, or no LUN is found and we are not
1259	 * sparse_lun.
1260	 */
1261	for (lun = 1; lun < max_dev_lun; ++lun)
1262		if ((scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan,
1263					    NULL) != SCSI_SCAN_LUN_PRESENT) &&
1264		    !sparse_lun)
1265			return;
1266}
1267
1268/**
1269 * scsi_report_lun_scan - Scan using SCSI REPORT LUN results
1270 * @starget: which target
1271 * @bflags: Zero or a mix of BLIST_NOLUN, BLIST_REPORTLUN2, or BLIST_NOREPORTLUN
1272 * @rescan: nonzero if we can skip code only needed on first scan
1273 *
1274 * Description:
1275 *   Fast scanning for modern (SCSI-3) devices by sending a REPORT LUN command.
1276 *   Scan the resulting list of LUNs by calling scsi_probe_and_add_lun.
1277 *
1278 *   If BLINK_REPORTLUN2 is set, scan a target that supports more than 8
1279 *   LUNs even if it's older than SCSI-3.
1280 *   If BLIST_NOREPORTLUN is set, return 1 always.
1281 *   If BLIST_NOLUN is set, return 0 always.
1282 *   If starget->no_report_luns is set, return 1 always.
1283 *
1284 * Return:
1285 *     0: scan completed (or no memory, so further scanning is futile)
1286 *     1: could not scan with REPORT LUN
1287 **/
1288static int scsi_report_lun_scan(struct scsi_target *starget, blist_flags_t bflags,
1289				enum scsi_scan_mode rescan)
1290{
1291	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
1292	unsigned int length;
1293	u64 lun;
1294	unsigned int num_luns;
1295	unsigned int retries;
1296	int result;
1297	struct scsi_lun *lunp, *lun_data;
1298	struct scsi_sense_hdr sshdr;
1299	struct scsi_device *sdev;
1300	struct Scsi_Host *shost = dev_to_shost(&starget->dev);
1301	int ret = 0;
1302
1303	/*
1304	 * Only support SCSI-3 and up devices if BLIST_NOREPORTLUN is not set.
1305	 * Also allow SCSI-2 if BLIST_REPORTLUN2 is set and host adapter does
1306	 * support more than 8 LUNs.
1307	 * Don't attempt if the target doesn't support REPORT LUNS.
1308	 */
1309	if (bflags & BLIST_NOREPORTLUN)
1310		return 1;
1311	if (starget->scsi_level < SCSI_2 &&
1312	    starget->scsi_level != SCSI_UNKNOWN)
1313		return 1;
1314	if (starget->scsi_level < SCSI_3 &&
1315	    (!(bflags & BLIST_REPORTLUN2) || shost->max_lun <= 8))
1316		return 1;
1317	if (bflags & BLIST_NOLUN)
1318		return 0;
1319	if (starget->no_report_luns)
1320		return 1;
1321
1322	if (!(sdev = scsi_device_lookup_by_target(starget, 0))) {
1323		sdev = scsi_alloc_sdev(starget, 0, NULL);
1324		if (!sdev)
1325			return 0;
1326		if (scsi_device_get(sdev)) {
1327			__scsi_remove_device(sdev);
1328			return 0;
1329		}
1330	}
1331
1332	/*
1333	 * Allocate enough to hold the header (the same size as one scsi_lun)
1334	 * plus the number of luns we are requesting.  511 was the default
1335	 * value of the now removed max_report_luns parameter.
1336	 */
1337	length = (511 + 1) * sizeof(struct scsi_lun);
1338retry:
1339	lun_data = kmalloc(length, GFP_KERNEL |
1340			   (sdev->host->unchecked_isa_dma ? __GFP_DMA : 0));
1341	if (!lun_data) {
1342		printk(ALLOC_FAILURE_MSG, __func__);
1343		goto out;
1344	}
1345
1346	scsi_cmd[0] = REPORT_LUNS;
1347
1348	/*
1349	 * bytes 1 - 5: reserved, set to zero.
1350	 */
1351	memset(&scsi_cmd[1], 0, 5);
1352
1353	/*
1354	 * bytes 6 - 9: length of the command.
1355	 */
1356	put_unaligned_be32(length, &scsi_cmd[6]);
1357
1358	scsi_cmd[10] = 0;	/* reserved */
1359	scsi_cmd[11] = 0;	/* control */
1360
1361	/*
1362	 * We can get a UNIT ATTENTION, for example a power on/reset, so
1363	 * retry a few times (like sd.c does for TEST UNIT READY).
1364	 * Experience shows some combinations of adapter/devices get at
1365	 * least two power on/resets.
1366	 *
1367	 * Illegal requests (for devices that do not support REPORT LUNS)
1368	 * should come through as a check condition, and will not generate
1369	 * a retry.
1370	 */
1371	for (retries = 0; retries < 3; retries++) {
1372		SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1373				"scsi scan: Sending REPORT LUNS to (try %d)\n",
1374				retries));
1375
1376		result = scsi_execute_req(sdev, scsi_cmd, DMA_FROM_DEVICE,
1377					  lun_data, length, &sshdr,
1378					  SCSI_REPORT_LUNS_TIMEOUT, 3, NULL);
1379
1380		SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1381				"scsi scan: REPORT LUNS"
1382				" %s (try %d) result 0x%x\n",
1383				result ?  "failed" : "successful",
1384				retries, result));
1385		if (result == 0)
1386			break;
1387		else if (scsi_sense_valid(&sshdr)) {
1388			if (sshdr.sense_key != UNIT_ATTENTION)
1389				break;
1390		}
1391	}
1392
1393	if (result) {
1394		/*
1395		 * The device probably does not support a REPORT LUN command
1396		 */
1397		ret = 1;
1398		goto out_err;
1399	}
1400
1401	/*
1402	 * Get the length from the first four bytes of lun_data.
1403	 */
1404	if (get_unaligned_be32(lun_data->scsi_lun) +
1405	    sizeof(struct scsi_lun) > length) {
1406		length = get_unaligned_be32(lun_data->scsi_lun) +
1407			 sizeof(struct scsi_lun);
1408		kfree(lun_data);
1409		goto retry;
1410	}
1411	length = get_unaligned_be32(lun_data->scsi_lun);
1412
1413	num_luns = (length / sizeof(struct scsi_lun));
1414
1415	SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1416		"scsi scan: REPORT LUN scan\n"));
1417
1418	/*
1419	 * Scan the luns in lun_data. The entry at offset 0 is really
1420	 * the header, so start at 1 and go up to and including num_luns.
1421	 */
1422	for (lunp = &lun_data[1]; lunp <= &lun_data[num_luns]; lunp++) {
1423		lun = scsilun_to_int(lunp);
1424
1425		if (lun > sdev->host->max_lun) {
1426			sdev_printk(KERN_WARNING, sdev,
1427				    "lun%llu has a LUN larger than"
1428				    " allowed by the host adapter\n", lun);
1429		} else {
1430			int res;
1431
1432			res = scsi_probe_and_add_lun(starget,
1433				lun, NULL, NULL, rescan, NULL);
1434			if (res == SCSI_SCAN_NO_RESPONSE) {
1435				/*
1436				 * Got some results, but now none, abort.
1437				 */
1438				sdev_printk(KERN_ERR, sdev,
1439					"Unexpected response"
1440					" from lun %llu while scanning, scan"
1441					" aborted\n", (unsigned long long)lun);
1442				break;
1443			}
1444		}
1445	}
1446
1447 out_err:
1448	kfree(lun_data);
1449 out:
1450	if (scsi_device_created(sdev))
1451		/*
1452		 * the sdev we used didn't appear in the report luns scan
1453		 */
1454		__scsi_remove_device(sdev);
1455	scsi_device_put(sdev);
1456	return ret;
1457}
1458
1459struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
1460				      uint id, u64 lun, void *hostdata)
1461{
1462	struct scsi_device *sdev = ERR_PTR(-ENODEV);
1463	struct device *parent = &shost->shost_gendev;
1464	struct scsi_target *starget;
1465
1466	if (strncmp(scsi_scan_type, "none", 4) == 0)
1467		return ERR_PTR(-ENODEV);
1468
1469	starget = scsi_alloc_target(parent, channel, id);
1470	if (!starget)
1471		return ERR_PTR(-ENOMEM);
1472	scsi_autopm_get_target(starget);
1473
1474	mutex_lock(&shost->scan_mutex);
1475	if (!shost->async_scan)
1476		scsi_complete_async_scans();
1477
1478	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1479		scsi_probe_and_add_lun(starget, lun, NULL, &sdev, 1, hostdata);
1480		scsi_autopm_put_host(shost);
1481	}
1482	mutex_unlock(&shost->scan_mutex);
1483	scsi_autopm_put_target(starget);
1484	/*
1485	 * paired with scsi_alloc_target().  Target will be destroyed unless
1486	 * scsi_probe_and_add_lun made an underlying device visible
1487	 */
1488	scsi_target_reap(starget);
1489	put_device(&starget->dev);
1490
1491	return sdev;
1492}
1493EXPORT_SYMBOL(__scsi_add_device);
1494
1495int scsi_add_device(struct Scsi_Host *host, uint channel,
1496		    uint target, u64 lun)
1497{
1498	struct scsi_device *sdev = 
1499		__scsi_add_device(host, channel, target, lun, NULL);
1500	if (IS_ERR(sdev))
1501		return PTR_ERR(sdev);
1502
1503	scsi_device_put(sdev);
1504	return 0;
1505}
1506EXPORT_SYMBOL(scsi_add_device);
1507
1508void scsi_rescan_device(struct device *dev)
1509{
1510	struct scsi_device *sdev = to_scsi_device(dev);
1511
1512	device_lock(dev);
1513
1514	scsi_attach_vpd(sdev);
1515
1516	if (sdev->handler && sdev->handler->rescan)
1517		sdev->handler->rescan(sdev);
1518
1519	if (dev->driver && try_module_get(dev->driver->owner)) {
1520		struct scsi_driver *drv = to_scsi_driver(dev->driver);
1521
1522		if (drv->rescan)
1523			drv->rescan(dev);
1524		module_put(dev->driver->owner);
1525	}
1526	device_unlock(dev);
1527}
1528EXPORT_SYMBOL(scsi_rescan_device);
1529
1530static void __scsi_scan_target(struct device *parent, unsigned int channel,
1531		unsigned int id, u64 lun, enum scsi_scan_mode rescan)
1532{
1533	struct Scsi_Host *shost = dev_to_shost(parent);
1534	blist_flags_t bflags = 0;
1535	int res;
1536	struct scsi_target *starget;
1537
1538	if (shost->this_id == id)
1539		/*
1540		 * Don't scan the host adapter
1541		 */
1542		return;
1543
1544	starget = scsi_alloc_target(parent, channel, id);
1545	if (!starget)
1546		return;
1547	scsi_autopm_get_target(starget);
1548
1549	if (lun != SCAN_WILD_CARD) {
1550		/*
1551		 * Scan for a specific host/chan/id/lun.
1552		 */
1553		scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan, NULL);
1554		goto out_reap;
1555	}
1556
1557	/*
1558	 * Scan LUN 0, if there is some response, scan further. Ideally, we
1559	 * would not configure LUN 0 until all LUNs are scanned.
1560	 */
1561	res = scsi_probe_and_add_lun(starget, 0, &bflags, NULL, rescan, NULL);
1562	if (res == SCSI_SCAN_LUN_PRESENT || res == SCSI_SCAN_TARGET_PRESENT) {
1563		if (scsi_report_lun_scan(starget, bflags, rescan) != 0)
1564			/*
1565			 * The REPORT LUN did not scan the target,
1566			 * do a sequential scan.
1567			 */
1568			scsi_sequential_lun_scan(starget, bflags,
1569						 starget->scsi_level, rescan);
1570	}
1571
1572 out_reap:
1573	scsi_autopm_put_target(starget);
1574	/*
1575	 * paired with scsi_alloc_target(): determine if the target has
1576	 * any children at all and if not, nuke it
1577	 */
1578	scsi_target_reap(starget);
1579
1580	put_device(&starget->dev);
1581}
1582
1583/**
1584 * scsi_scan_target - scan a target id, possibly including all LUNs on the target.
1585 * @parent:	host to scan
1586 * @channel:	channel to scan
1587 * @id:		target id to scan
1588 * @lun:	Specific LUN to scan or SCAN_WILD_CARD
1589 * @rescan:	passed to LUN scanning routines; SCSI_SCAN_INITIAL for
1590 *              no rescan, SCSI_SCAN_RESCAN to rescan existing LUNs,
1591 *              and SCSI_SCAN_MANUAL to force scanning even if
1592 *              'scan=manual' is set.
1593 *
1594 * Description:
1595 *     Scan the target id on @parent, @channel, and @id. Scan at least LUN 0,
1596 *     and possibly all LUNs on the target id.
1597 *
1598 *     First try a REPORT LUN scan, if that does not scan the target, do a
1599 *     sequential scan of LUNs on the target id.
1600 **/
1601void scsi_scan_target(struct device *parent, unsigned int channel,
1602		      unsigned int id, u64 lun, enum scsi_scan_mode rescan)
1603{
1604	struct Scsi_Host *shost = dev_to_shost(parent);
1605
1606	if (strncmp(scsi_scan_type, "none", 4) == 0)
1607		return;
1608
1609	if (rescan != SCSI_SCAN_MANUAL &&
1610	    strncmp(scsi_scan_type, "manual", 6) == 0)
1611		return;
1612
1613	mutex_lock(&shost->scan_mutex);
1614	if (!shost->async_scan)
1615		scsi_complete_async_scans();
1616
1617	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1618		__scsi_scan_target(parent, channel, id, lun, rescan);
1619		scsi_autopm_put_host(shost);
1620	}
1621	mutex_unlock(&shost->scan_mutex);
1622}
1623EXPORT_SYMBOL(scsi_scan_target);
1624
1625static void scsi_scan_channel(struct Scsi_Host *shost, unsigned int channel,
1626			      unsigned int id, u64 lun,
1627			      enum scsi_scan_mode rescan)
1628{
1629	uint order_id;
1630
1631	if (id == SCAN_WILD_CARD)
1632		for (id = 0; id < shost->max_id; ++id) {
1633			/*
1634			 * XXX adapter drivers when possible (FCP, iSCSI)
1635			 * could modify max_id to match the current max,
1636			 * not the absolute max.
1637			 *
1638			 * XXX add a shost id iterator, so for example,
1639			 * the FC ID can be the same as a target id
1640			 * without a huge overhead of sparse id's.
1641			 */
1642			if (shost->reverse_ordering)
1643				/*
1644				 * Scan from high to low id.
1645				 */
1646				order_id = shost->max_id - id - 1;
1647			else
1648				order_id = id;
1649			__scsi_scan_target(&shost->shost_gendev, channel,
1650					order_id, lun, rescan);
1651		}
1652	else
1653		__scsi_scan_target(&shost->shost_gendev, channel,
1654				id, lun, rescan);
1655}
1656
1657int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel,
1658			    unsigned int id, u64 lun,
1659			    enum scsi_scan_mode rescan)
1660{
1661	SCSI_LOG_SCAN_BUS(3, shost_printk (KERN_INFO, shost,
1662		"%s: <%u:%u:%llu>\n",
1663		__func__, channel, id, lun));
1664
1665	if (((channel != SCAN_WILD_CARD) && (channel > shost->max_channel)) ||
1666	    ((id != SCAN_WILD_CARD) && (id >= shost->max_id)) ||
1667	    ((lun != SCAN_WILD_CARD) && (lun >= shost->max_lun)))
1668		return -EINVAL;
1669
1670	mutex_lock(&shost->scan_mutex);
1671	if (!shost->async_scan)
1672		scsi_complete_async_scans();
1673
1674	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1675		if (channel == SCAN_WILD_CARD)
1676			for (channel = 0; channel <= shost->max_channel;
1677			     channel++)
1678				scsi_scan_channel(shost, channel, id, lun,
1679						  rescan);
1680		else
1681			scsi_scan_channel(shost, channel, id, lun, rescan);
1682		scsi_autopm_put_host(shost);
1683	}
1684	mutex_unlock(&shost->scan_mutex);
1685
1686	return 0;
1687}
1688
1689static void scsi_sysfs_add_devices(struct Scsi_Host *shost)
1690{
1691	struct scsi_device *sdev;
1692	shost_for_each_device(sdev, shost) {
1693		/* target removed before the device could be added */
1694		if (sdev->sdev_state == SDEV_DEL)
1695			continue;
1696		/* If device is already visible, skip adding it to sysfs */
1697		if (sdev->is_visible)
1698			continue;
1699		if (!scsi_host_scan_allowed(shost) ||
1700		    scsi_sysfs_add_sdev(sdev) != 0)
1701			__scsi_remove_device(sdev);
1702	}
1703}
1704
1705/**
1706 * scsi_prep_async_scan - prepare for an async scan
1707 * @shost: the host which will be scanned
1708 * Returns: a cookie to be passed to scsi_finish_async_scan()
1709 *
1710 * Tells the midlayer this host is going to do an asynchronous scan.
1711 * It reserves the host's position in the scanning list and ensures
1712 * that other asynchronous scans started after this one won't affect the
1713 * ordering of the discovered devices.
1714 */
1715static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost)
1716{
1717	struct async_scan_data *data;
1718	unsigned long flags;
1719
1720	if (strncmp(scsi_scan_type, "sync", 4) == 0)
1721		return NULL;
1722
1723	if (shost->async_scan) {
1724		shost_printk(KERN_DEBUG, shost, "%s called twice\n", __func__);
1725		return NULL;
1726	}
1727
1728	data = kmalloc(sizeof(*data), GFP_KERNEL);
1729	if (!data)
1730		goto err;
1731	data->shost = scsi_host_get(shost);
1732	if (!data->shost)
1733		goto err;
1734	init_completion(&data->prev_finished);
1735
1736	mutex_lock(&shost->scan_mutex);
1737	spin_lock_irqsave(shost->host_lock, flags);
1738	shost->async_scan = 1;
1739	spin_unlock_irqrestore(shost->host_lock, flags);
1740	mutex_unlock(&shost->scan_mutex);
1741
1742	spin_lock(&async_scan_lock);
1743	if (list_empty(&scanning_hosts))
1744		complete(&data->prev_finished);
1745	list_add_tail(&data->list, &scanning_hosts);
1746	spin_unlock(&async_scan_lock);
1747
1748	return data;
1749
1750 err:
1751	kfree(data);
1752	return NULL;
1753}
1754
1755/**
1756 * scsi_finish_async_scan - asynchronous scan has finished
1757 * @data: cookie returned from earlier call to scsi_prep_async_scan()
1758 *
1759 * All the devices currently attached to this host have been found.
1760 * This function announces all the devices it has found to the rest
1761 * of the system.
1762 */
1763static void scsi_finish_async_scan(struct async_scan_data *data)
1764{
1765	struct Scsi_Host *shost;
1766	unsigned long flags;
1767
1768	if (!data)
1769		return;
1770
1771	shost = data->shost;
1772
1773	mutex_lock(&shost->scan_mutex);
1774
1775	if (!shost->async_scan) {
1776		shost_printk(KERN_INFO, shost, "%s called twice\n", __func__);
1777		dump_stack();
1778		mutex_unlock(&shost->scan_mutex);
1779		return;
1780	}
1781
1782	wait_for_completion(&data->prev_finished);
1783
1784	scsi_sysfs_add_devices(shost);
1785
1786	spin_lock_irqsave(shost->host_lock, flags);
1787	shost->async_scan = 0;
1788	spin_unlock_irqrestore(shost->host_lock, flags);
1789
1790	mutex_unlock(&shost->scan_mutex);
1791
1792	spin_lock(&async_scan_lock);
1793	list_del(&data->list);
1794	if (!list_empty(&scanning_hosts)) {
1795		struct async_scan_data *next = list_entry(scanning_hosts.next,
1796				struct async_scan_data, list);
1797		complete(&next->prev_finished);
1798	}
1799	spin_unlock(&async_scan_lock);
1800
1801	scsi_autopm_put_host(shost);
1802	scsi_host_put(shost);
1803	kfree(data);
1804}
1805
1806static void do_scsi_scan_host(struct Scsi_Host *shost)
1807{
1808	if (shost->hostt->scan_finished) {
1809		unsigned long start = jiffies;
1810		if (shost->hostt->scan_start)
1811			shost->hostt->scan_start(shost);
1812
1813		while (!shost->hostt->scan_finished(shost, jiffies - start))
1814			msleep(10);
1815	} else {
1816		scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD,
1817				SCAN_WILD_CARD, 0);
1818	}
1819}
1820
1821static void do_scan_async(void *_data, async_cookie_t c)
1822{
1823	struct async_scan_data *data = _data;
1824	struct Scsi_Host *shost = data->shost;
1825
1826	do_scsi_scan_host(shost);
1827	scsi_finish_async_scan(data);
1828}
1829
1830/**
1831 * scsi_scan_host - scan the given adapter
1832 * @shost:	adapter to scan
1833 **/
1834void scsi_scan_host(struct Scsi_Host *shost)
1835{
1836	struct async_scan_data *data;
1837
1838	if (strncmp(scsi_scan_type, "none", 4) == 0 ||
1839	    strncmp(scsi_scan_type, "manual", 6) == 0)
1840		return;
1841	if (scsi_autopm_get_host(shost) < 0)
1842		return;
1843
1844	data = scsi_prep_async_scan(shost);
1845	if (!data) {
1846		do_scsi_scan_host(shost);
1847		scsi_autopm_put_host(shost);
1848		return;
1849	}
1850
1851	/* register with the async subsystem so wait_for_device_probe()
1852	 * will flush this work
1853	 */
1854	async_schedule(do_scan_async, data);
1855
1856	/* scsi_autopm_put_host(shost) is called in scsi_finish_async_scan() */
1857}
1858EXPORT_SYMBOL(scsi_scan_host);
1859
1860void scsi_forget_host(struct Scsi_Host *shost)
1861{
1862	struct scsi_device *sdev;
1863	unsigned long flags;
1864
1865 restart:
1866	spin_lock_irqsave(shost->host_lock, flags);
1867	list_for_each_entry(sdev, &shost->__devices, siblings) {
1868		if (sdev->sdev_state == SDEV_DEL)
1869			continue;
1870		spin_unlock_irqrestore(shost->host_lock, flags);
1871		__scsi_remove_device(sdev);
1872		goto restart;
1873	}
1874	spin_unlock_irqrestore(shost->host_lock, flags);
1875}
1876
1877/**
1878 * scsi_get_host_dev - Create a scsi_device that points to the host adapter itself
1879 * @shost: Host that needs a scsi_device
1880 *
1881 * Lock status: None assumed.
1882 *
1883 * Returns:     The scsi_device or NULL
1884 *
1885 * Notes:
1886 *	Attach a single scsi_device to the Scsi_Host - this should
1887 *	be made to look like a "pseudo-device" that points to the
1888 *	HA itself.
1889 *
1890 *	Note - this device is not accessible from any high-level
1891 *	drivers (including generics), which is probably not
1892 *	optimal.  We can add hooks later to attach.
1893 */
1894struct scsi_device *scsi_get_host_dev(struct Scsi_Host *shost)
1895{
1896	struct scsi_device *sdev = NULL;
1897	struct scsi_target *starget;
1898
1899	mutex_lock(&shost->scan_mutex);
1900	if (!scsi_host_scan_allowed(shost))
1901		goto out;
1902	starget = scsi_alloc_target(&shost->shost_gendev, 0, shost->this_id);
1903	if (!starget)
1904		goto out;
1905
1906	sdev = scsi_alloc_sdev(starget, 0, NULL);
1907	if (sdev)
1908		sdev->borken = 0;
1909	else
1910		scsi_target_reap(starget);
1911	put_device(&starget->dev);
1912 out:
1913	mutex_unlock(&shost->scan_mutex);
1914	return sdev;
1915}
1916EXPORT_SYMBOL(scsi_get_host_dev);
1917
1918/**
1919 * scsi_free_host_dev - Free a scsi_device that points to the host adapter itself
1920 * @sdev: Host device to be freed
1921 *
1922 * Lock status: None assumed.
1923 *
1924 * Returns:     Nothing
1925 */
1926void scsi_free_host_dev(struct scsi_device *sdev)
1927{
1928	BUG_ON(sdev->id != sdev->host->this_id);
1929
1930	__scsi_remove_device(sdev);
1931}
1932EXPORT_SYMBOL(scsi_free_host_dev);
1933