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
 100static char 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_enable_async_suspend - Enable async suspend and resume
 127 */
 128void scsi_enable_async_suspend(struct device *dev)
 129{
 130	/*
 131	 * If a user has disabled async probing a likely reason is due to a
 132	 * storage enclosure that does not inject staggered spin-ups. For
 133	 * safety, make resume synchronous as well in that case.
 134	 */
 135	if (strncmp(scsi_scan_type, "async", 5) != 0)
 136		return;
 137	/* Enable asynchronous suspend and resume. */
 138	device_enable_async_suspend(dev);
 139}
 140
 141/**
 142 * scsi_complete_async_scans - Wait for asynchronous scans to complete
 143 *
 144 * When this function returns, any host which started scanning before
 145 * this function was called will have finished its scan.  Hosts which
 146 * started scanning after this function was called may or may not have
 147 * finished.
 148 */
 149int scsi_complete_async_scans(void)
 150{
 151	struct async_scan_data *data;
 152
 153	do {
 154		if (list_empty(&scanning_hosts))
 155			return 0;
 156		/* If we can't get memory immediately, that's OK.  Just
 157		 * sleep a little.  Even if we never get memory, the async
 158		 * scans will finish eventually.
 159		 */
 160		data = kmalloc(sizeof(*data), GFP_KERNEL);
 161		if (!data)
 162			msleep(1);
 163	} while (!data);
 164
 165	data->shost = NULL;
 166	init_completion(&data->prev_finished);
 167
 168	spin_lock(&async_scan_lock);
 169	/* Check that there's still somebody else on the list */
 170	if (list_empty(&scanning_hosts))
 171		goto done;
 172	list_add_tail(&data->list, &scanning_hosts);
 173	spin_unlock(&async_scan_lock);
 174
 175	printk(KERN_INFO "scsi: waiting for bus probes to complete ...\n");
 176	wait_for_completion(&data->prev_finished);
 177
 178	spin_lock(&async_scan_lock);
 179	list_del(&data->list);
 180	if (!list_empty(&scanning_hosts)) {
 181		struct async_scan_data *next = list_entry(scanning_hosts.next,
 182				struct async_scan_data, list);
 183		complete(&next->prev_finished);
 184	}
 185 done:
 186	spin_unlock(&async_scan_lock);
 187
 188	kfree(data);
 189	return 0;
 190}
 191
 192/**
 193 * scsi_unlock_floptical - unlock device via a special MODE SENSE command
 194 * @sdev:	scsi device to send command to
 195 * @result:	area to store the result of the MODE SENSE
 196 *
 197 * Description:
 198 *     Send a vendor specific MODE SENSE (not a MODE SELECT) command.
 199 *     Called for BLIST_KEY devices.
 200 **/
 201static void scsi_unlock_floptical(struct scsi_device *sdev,
 202				  unsigned char *result)
 203{
 204	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
 205
 206	sdev_printk(KERN_NOTICE, sdev, "unlocking floptical drive\n");
 207	scsi_cmd[0] = MODE_SENSE;
 208	scsi_cmd[1] = 0;
 209	scsi_cmd[2] = 0x2e;
 210	scsi_cmd[3] = 0;
 211	scsi_cmd[4] = 0x2a;     /* size */
 212	scsi_cmd[5] = 0;
 213	scsi_execute_cmd(sdev, scsi_cmd, REQ_OP_DRV_IN, result, 0x2a,
 214			 SCSI_TIMEOUT, 3, NULL);
 215}
 216
 217static int scsi_realloc_sdev_budget_map(struct scsi_device *sdev,
 218					unsigned int depth)
 219{
 220	int new_shift = sbitmap_calculate_shift(depth);
 221	bool need_alloc = !sdev->budget_map.map;
 222	bool need_free = false;
 223	int ret;
 224	struct sbitmap sb_backup;
 225
 226	depth = min_t(unsigned int, depth, scsi_device_max_queue_depth(sdev));
 227
 228	/*
 229	 * realloc if new shift is calculated, which is caused by setting
 230	 * up one new default queue depth after calling ->slave_configure
 231	 */
 232	if (!need_alloc && new_shift != sdev->budget_map.shift)
 233		need_alloc = need_free = true;
 234
 235	if (!need_alloc)
 236		return 0;
 237
 238	/*
 239	 * Request queue has to be frozen for reallocating budget map,
 240	 * and here disk isn't added yet, so freezing is pretty fast
 241	 */
 242	if (need_free) {
 243		blk_mq_freeze_queue(sdev->request_queue);
 244		sb_backup = sdev->budget_map;
 245	}
 246	ret = sbitmap_init_node(&sdev->budget_map,
 247				scsi_device_max_queue_depth(sdev),
 248				new_shift, GFP_KERNEL,
 249				sdev->request_queue->node, false, true);
 250	if (!ret)
 251		sbitmap_resize(&sdev->budget_map, depth);
 252
 253	if (need_free) {
 254		if (ret)
 255			sdev->budget_map = sb_backup;
 256		else
 257			sbitmap_free(&sb_backup);
 258		ret = 0;
 259		blk_mq_unfreeze_queue(sdev->request_queue);
 260	}
 261	return ret;
 262}
 263
 264/**
 265 * scsi_alloc_sdev - allocate and setup a scsi_Device
 266 * @starget: which target to allocate a &scsi_device for
 267 * @lun: which lun
 268 * @hostdata: usually NULL and set by ->slave_alloc instead
 269 *
 270 * Description:
 271 *     Allocate, initialize for io, and return a pointer to a scsi_Device.
 272 *     Stores the @shost, @channel, @id, and @lun in the scsi_Device, and
 273 *     adds scsi_Device to the appropriate list.
 274 *
 275 * Return value:
 276 *     scsi_Device pointer, or NULL on failure.
 277 **/
 278static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
 279					   u64 lun, void *hostdata)
 280{
 281	unsigned int depth;
 282	struct scsi_device *sdev;
 283	struct request_queue *q;
 284	int display_failure_msg = 1, ret;
 285	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 286
 287	sdev = kzalloc(sizeof(*sdev) + shost->transportt->device_size,
 288		       GFP_KERNEL);
 289	if (!sdev)
 290		goto out;
 291
 292	sdev->vendor = scsi_null_device_strs;
 293	sdev->model = scsi_null_device_strs;
 294	sdev->rev = scsi_null_device_strs;
 295	sdev->host = shost;
 296	sdev->queue_ramp_up_period = SCSI_DEFAULT_RAMP_UP_PERIOD;
 297	sdev->id = starget->id;
 298	sdev->lun = lun;
 299	sdev->channel = starget->channel;
 300	mutex_init(&sdev->state_mutex);
 301	sdev->sdev_state = SDEV_CREATED;
 302	INIT_LIST_HEAD(&sdev->siblings);
 303	INIT_LIST_HEAD(&sdev->same_target_siblings);
 304	INIT_LIST_HEAD(&sdev->starved_entry);
 305	INIT_LIST_HEAD(&sdev->event_list);
 306	spin_lock_init(&sdev->list_lock);
 307	mutex_init(&sdev->inquiry_mutex);
 308	INIT_WORK(&sdev->event_work, scsi_evt_thread);
 309	INIT_WORK(&sdev->requeue_work, scsi_requeue_run_queue);
 310
 311	sdev->sdev_gendev.parent = get_device(&starget->dev);
 312	sdev->sdev_target = starget;
 313
 314	/* usually NULL and set by ->slave_alloc instead */
 315	sdev->hostdata = hostdata;
 316
 317	/* if the device needs this changing, it may do so in the
 318	 * slave_configure function */
 319	sdev->max_device_blocked = SCSI_DEFAULT_DEVICE_BLOCKED;
 320
 321	/*
 322	 * Some low level driver could use device->type
 323	 */
 324	sdev->type = -1;
 325
 326	/*
 327	 * Assume that the device will have handshaking problems,
 328	 * and then fix this field later if it turns out it
 329	 * doesn't
 330	 */
 331	sdev->borken = 1;
 332
 333	sdev->sg_reserved_size = INT_MAX;
 334
 335	q = blk_mq_init_queue(&sdev->host->tag_set);
 336	if (IS_ERR(q)) {
 337		/* release fn is set up in scsi_sysfs_device_initialise, so
 338		 * have to free and put manually here */
 339		put_device(&starget->dev);
 340		kfree(sdev);
 341		goto out;
 342	}
 343	kref_get(&sdev->host->tagset_refcnt);
 344	sdev->request_queue = q;
 345	q->queuedata = sdev;
 346	__scsi_init_queue(sdev->host, q);
 347
 348	depth = sdev->host->cmd_per_lun ?: 1;
 349
 350	/*
 351	 * Use .can_queue as budget map's depth because we have to
 352	 * support adjusting queue depth from sysfs. Meantime use
 353	 * default device queue depth to figure out sbitmap shift
 354	 * since we use this queue depth most of times.
 355	 */
 356	if (scsi_realloc_sdev_budget_map(sdev, depth)) {
 357		put_device(&starget->dev);
 358		kfree(sdev);
 359		goto out;
 360	}
 361
 362	scsi_change_queue_depth(sdev, depth);
 363
 364	scsi_sysfs_device_initialize(sdev);
 365
 366	if (shost->hostt->slave_alloc) {
 367		ret = shost->hostt->slave_alloc(sdev);
 368		if (ret) {
 369			/*
 370			 * if LLDD reports slave not present, don't clutter
 371			 * console with alloc failure messages
 372			 */
 373			if (ret == -ENXIO)
 374				display_failure_msg = 0;
 375			goto out_device_destroy;
 376		}
 377	}
 378
 379	return sdev;
 380
 381out_device_destroy:
 382	__scsi_remove_device(sdev);
 383out:
 384	if (display_failure_msg)
 385		printk(ALLOC_FAILURE_MSG, __func__);
 386	return NULL;
 387}
 388
 389static void scsi_target_destroy(struct scsi_target *starget)
 390{
 391	struct device *dev = &starget->dev;
 392	struct Scsi_Host *shost = dev_to_shost(dev->parent);
 393	unsigned long flags;
 394
 395	BUG_ON(starget->state == STARGET_DEL);
 396	starget->state = STARGET_DEL;
 397	transport_destroy_device(dev);
 398	spin_lock_irqsave(shost->host_lock, flags);
 399	if (shost->hostt->target_destroy)
 400		shost->hostt->target_destroy(starget);
 401	list_del_init(&starget->siblings);
 402	spin_unlock_irqrestore(shost->host_lock, flags);
 403	put_device(dev);
 404}
 405
 406static void scsi_target_dev_release(struct device *dev)
 407{
 408	struct device *parent = dev->parent;
 409	struct scsi_target *starget = to_scsi_target(dev);
 410
 411	kfree(starget);
 412	put_device(parent);
 413}
 414
 415static struct device_type scsi_target_type = {
 416	.name =		"scsi_target",
 417	.release =	scsi_target_dev_release,
 418};
 419
 420int scsi_is_target_device(const struct device *dev)
 421{
 422	return dev->type == &scsi_target_type;
 423}
 424EXPORT_SYMBOL(scsi_is_target_device);
 425
 426static struct scsi_target *__scsi_find_target(struct device *parent,
 427					      int channel, uint id)
 428{
 429	struct scsi_target *starget, *found_starget = NULL;
 430	struct Scsi_Host *shost = dev_to_shost(parent);
 431	/*
 432	 * Search for an existing target for this sdev.
 433	 */
 434	list_for_each_entry(starget, &shost->__targets, siblings) {
 435		if (starget->id == id &&
 436		    starget->channel == channel) {
 437			found_starget = starget;
 438			break;
 439		}
 440	}
 441	if (found_starget)
 442		get_device(&found_starget->dev);
 443
 444	return found_starget;
 445}
 446
 447/**
 448 * scsi_target_reap_ref_release - remove target from visibility
 449 * @kref: the reap_ref in the target being released
 450 *
 451 * Called on last put of reap_ref, which is the indication that no device
 452 * under this target is visible anymore, so render the target invisible in
 453 * sysfs.  Note: we have to be in user context here because the target reaps
 454 * should be done in places where the scsi device visibility is being removed.
 455 */
 456static void scsi_target_reap_ref_release(struct kref *kref)
 457{
 458	struct scsi_target *starget
 459		= container_of(kref, struct scsi_target, reap_ref);
 460
 461	/*
 462	 * if we get here and the target is still in a CREATED state that
 463	 * means it was allocated but never made visible (because a scan
 464	 * turned up no LUNs), so don't call device_del() on it.
 465	 */
 466	if ((starget->state != STARGET_CREATED) &&
 467	    (starget->state != STARGET_CREATED_REMOVE)) {
 468		transport_remove_device(&starget->dev);
 469		device_del(&starget->dev);
 470	}
 471	scsi_target_destroy(starget);
 472}
 473
 474static void scsi_target_reap_ref_put(struct scsi_target *starget)
 475{
 476	kref_put(&starget->reap_ref, scsi_target_reap_ref_release);
 477}
 478
 479/**
 480 * scsi_alloc_target - allocate a new or find an existing target
 481 * @parent:	parent of the target (need not be a scsi host)
 482 * @channel:	target channel number (zero if no channels)
 483 * @id:		target id number
 484 *
 485 * Return an existing target if one exists, provided it hasn't already
 486 * gone into STARGET_DEL state, otherwise allocate a new target.
 487 *
 488 * The target is returned with an incremented reference, so the caller
 489 * is responsible for both reaping and doing a last put
 490 */
 491static struct scsi_target *scsi_alloc_target(struct device *parent,
 492					     int channel, uint id)
 493{
 494	struct Scsi_Host *shost = dev_to_shost(parent);
 495	struct device *dev = NULL;
 496	unsigned long flags;
 497	const int size = sizeof(struct scsi_target)
 498		+ shost->transportt->target_size;
 499	struct scsi_target *starget;
 500	struct scsi_target *found_target;
 501	int error, ref_got;
 502
 503	starget = kzalloc(size, GFP_KERNEL);
 504	if (!starget) {
 505		printk(KERN_ERR "%s: allocation failure\n", __func__);
 506		return NULL;
 507	}
 508	dev = &starget->dev;
 509	device_initialize(dev);
 510	kref_init(&starget->reap_ref);
 511	dev->parent = get_device(parent);
 512	dev_set_name(dev, "target%d:%d:%d", shost->host_no, channel, id);
 513	dev->bus = &scsi_bus_type;
 514	dev->type = &scsi_target_type;
 515	scsi_enable_async_suspend(dev);
 516	starget->id = id;
 517	starget->channel = channel;
 518	starget->can_queue = 0;
 519	INIT_LIST_HEAD(&starget->siblings);
 520	INIT_LIST_HEAD(&starget->devices);
 521	starget->state = STARGET_CREATED;
 522	starget->scsi_level = SCSI_2;
 523	starget->max_target_blocked = SCSI_DEFAULT_TARGET_BLOCKED;
 524 retry:
 525	spin_lock_irqsave(shost->host_lock, flags);
 526
 527	found_target = __scsi_find_target(parent, channel, id);
 528	if (found_target)
 529		goto found;
 530
 531	list_add_tail(&starget->siblings, &shost->__targets);
 532	spin_unlock_irqrestore(shost->host_lock, flags);
 533	/* allocate and add */
 534	transport_setup_device(dev);
 535	if (shost->hostt->target_alloc) {
 536		error = shost->hostt->target_alloc(starget);
 537
 538		if(error) {
 539			if (error != -ENXIO)
 540				dev_err(dev, "target allocation failed, error %d\n", error);
 541			/* don't want scsi_target_reap to do the final
 542			 * put because it will be under the host lock */
 543			scsi_target_destroy(starget);
 544			return NULL;
 545		}
 546	}
 547	get_device(dev);
 548
 549	return starget;
 550
 551 found:
 552	/*
 553	 * release routine already fired if kref is zero, so if we can still
 554	 * take the reference, the target must be alive.  If we can't, it must
 555	 * be dying and we need to wait for a new target
 556	 */
 557	ref_got = kref_get_unless_zero(&found_target->reap_ref);
 558
 559	spin_unlock_irqrestore(shost->host_lock, flags);
 560	if (ref_got) {
 561		put_device(dev);
 562		return found_target;
 563	}
 564	/*
 565	 * Unfortunately, we found a dying target; need to wait until it's
 566	 * dead before we can get a new one.  There is an anomaly here.  We
 567	 * *should* call scsi_target_reap() to balance the kref_get() of the
 568	 * reap_ref above.  However, since the target being released, it's
 569	 * already invisible and the reap_ref is irrelevant.  If we call
 570	 * scsi_target_reap() we might spuriously do another device_del() on
 571	 * an already invisible target.
 572	 */
 573	put_device(&found_target->dev);
 574	/*
 575	 * length of time is irrelevant here, we just want to yield the CPU
 576	 * for a tick to avoid busy waiting for the target to die.
 577	 */
 578	msleep(1);
 579	goto retry;
 580}
 581
 582/**
 583 * scsi_target_reap - check to see if target is in use and destroy if not
 584 * @starget: target to be checked
 585 *
 586 * This is used after removing a LUN or doing a last put of the target
 587 * it checks atomically that nothing is using the target and removes
 588 * it if so.
 589 */
 590void scsi_target_reap(struct scsi_target *starget)
 591{
 592	/*
 593	 * serious problem if this triggers: STARGET_DEL is only set in the if
 594	 * the reap_ref drops to zero, so we're trying to do another final put
 595	 * on an already released kref
 596	 */
 597	BUG_ON(starget->state == STARGET_DEL);
 598	scsi_target_reap_ref_put(starget);
 599}
 600
 601/**
 602 * scsi_sanitize_inquiry_string - remove non-graphical chars from an
 603 *                                INQUIRY result string
 604 * @s: INQUIRY result string to sanitize
 605 * @len: length of the string
 606 *
 607 * Description:
 608 *	The SCSI spec says that INQUIRY vendor, product, and revision
 609 *	strings must consist entirely of graphic ASCII characters,
 610 *	padded on the right with spaces.  Since not all devices obey
 611 *	this rule, we will replace non-graphic or non-ASCII characters
 612 *	with spaces.  Exception: a NUL character is interpreted as a
 613 *	string terminator, so all the following characters are set to
 614 *	spaces.
 615 **/
 616void scsi_sanitize_inquiry_string(unsigned char *s, int len)
 617{
 618	int terminated = 0;
 619
 620	for (; len > 0; (--len, ++s)) {
 621		if (*s == 0)
 622			terminated = 1;
 623		if (terminated || *s < 0x20 || *s > 0x7e)
 624			*s = ' ';
 625	}
 626}
 627EXPORT_SYMBOL(scsi_sanitize_inquiry_string);
 628
 629/**
 630 * scsi_probe_lun - probe a single LUN using a SCSI INQUIRY
 631 * @sdev:	scsi_device to probe
 632 * @inq_result:	area to store the INQUIRY result
 633 * @result_len: len of inq_result
 634 * @bflags:	store any bflags found here
 635 *
 636 * Description:
 637 *     Probe the lun associated with @req using a standard SCSI INQUIRY;
 638 *
 639 *     If the INQUIRY is successful, zero is returned and the
 640 *     INQUIRY data is in @inq_result; the scsi_level and INQUIRY length
 641 *     are copied to the scsi_device any flags value is stored in *@bflags.
 642 **/
 643static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result,
 644			  int result_len, blist_flags_t *bflags)
 645{
 646	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
 647	int first_inquiry_len, try_inquiry_len, next_inquiry_len;
 648	int response_len = 0;
 649	int pass, count, result, resid;
 650	struct scsi_sense_hdr sshdr;
 651	const struct scsi_exec_args exec_args = {
 652		.sshdr = &sshdr,
 653		.resid = &resid,
 654	};
 655
 656	*bflags = 0;
 657
 658	/* Perform up to 3 passes.  The first pass uses a conservative
 659	 * transfer length of 36 unless sdev->inquiry_len specifies a
 660	 * different value. */
 661	first_inquiry_len = sdev->inquiry_len ? sdev->inquiry_len : 36;
 662	try_inquiry_len = first_inquiry_len;
 663	pass = 1;
 664
 665 next_pass:
 666	SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
 667				"scsi scan: INQUIRY pass %d length %d\n",
 668				pass, try_inquiry_len));
 669
 670	/* Each pass gets up to three chances to ignore Unit Attention */
 671	for (count = 0; count < 3; ++count) {
 
 
 672		memset(scsi_cmd, 0, 6);
 673		scsi_cmd[0] = INQUIRY;
 674		scsi_cmd[4] = (unsigned char) try_inquiry_len;
 675
 676		memset(inq_result, 0, try_inquiry_len);
 677
 678		result = scsi_execute_cmd(sdev,  scsi_cmd, REQ_OP_DRV_IN,
 679					  inq_result, try_inquiry_len,
 680					  HZ / 2 + HZ * scsi_inq_timeout, 3,
 681					  &exec_args);
 682
 683		SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
 684				"scsi scan: INQUIRY %s with code 0x%x\n",
 685				result ? "failed" : "successful", result));
 686
 687		if (result > 0) {
 688			/*
 689			 * not-ready to ready transition [asc/ascq=0x28/0x0]
 690			 * or power-on, reset [asc/ascq=0x29/0x0], continue.
 691			 * INQUIRY should not yield UNIT_ATTENTION
 692			 * but many buggy devices do so anyway. 
 693			 */
 694			if (scsi_status_is_check_condition(result) &&
 695			    scsi_sense_valid(&sshdr)) {
 696				if ((sshdr.sense_key == UNIT_ATTENTION) &&
 697				    ((sshdr.asc == 0x28) ||
 698				     (sshdr.asc == 0x29)) &&
 699				    (sshdr.ascq == 0))
 700					continue;
 701			}
 702		} else if (result == 0) {
 703			/*
 704			 * if nothing was transferred, we try
 705			 * again. It's a workaround for some USB
 706			 * devices.
 707			 */
 708			if (resid == try_inquiry_len)
 709				continue;
 710		}
 711		break;
 712	}
 713
 714	if (result == 0) {
 715		scsi_sanitize_inquiry_string(&inq_result[8], 8);
 716		scsi_sanitize_inquiry_string(&inq_result[16], 16);
 717		scsi_sanitize_inquiry_string(&inq_result[32], 4);
 718
 719		response_len = inq_result[4] + 5;
 720		if (response_len > 255)
 721			response_len = first_inquiry_len;	/* sanity */
 722
 723		/*
 724		 * Get any flags for this device.
 725		 *
 726		 * XXX add a bflags to scsi_device, and replace the
 727		 * corresponding bit fields in scsi_device, so bflags
 728		 * need not be passed as an argument.
 729		 */
 730		*bflags = scsi_get_device_flags(sdev, &inq_result[8],
 731				&inq_result[16]);
 732
 733		/* When the first pass succeeds we gain information about
 734		 * what larger transfer lengths might work. */
 735		if (pass == 1) {
 736			if (BLIST_INQUIRY_36 & *bflags)
 737				next_inquiry_len = 36;
 738			/*
 739			 * LLD specified a maximum sdev->inquiry_len
 740			 * but device claims it has more data. Capping
 741			 * the length only makes sense for legacy
 742			 * devices. If a device supports SPC-4 (2014)
 743			 * or newer, assume that it is safe to ask for
 744			 * as much as the device says it supports.
 745			 */
 746			else if (sdev->inquiry_len &&
 747				 response_len > sdev->inquiry_len &&
 748				 (inq_result[2] & 0x7) < 6) /* SPC-4 */
 749				next_inquiry_len = sdev->inquiry_len;
 750			else
 751				next_inquiry_len = response_len;
 752
 753			/* If more data is available perform the second pass */
 754			if (next_inquiry_len > try_inquiry_len) {
 755				try_inquiry_len = next_inquiry_len;
 756				pass = 2;
 757				goto next_pass;
 758			}
 759		}
 760
 761	} else if (pass == 2) {
 762		sdev_printk(KERN_INFO, sdev,
 763			    "scsi scan: %d byte inquiry failed.  "
 764			    "Consider BLIST_INQUIRY_36 for this device\n",
 765			    try_inquiry_len);
 766
 767		/* If this pass failed, the third pass goes back and transfers
 768		 * the same amount as we successfully got in the first pass. */
 769		try_inquiry_len = first_inquiry_len;
 770		pass = 3;
 771		goto next_pass;
 772	}
 773
 774	/* If the last transfer attempt got an error, assume the
 775	 * peripheral doesn't exist or is dead. */
 776	if (result)
 777		return -EIO;
 778
 779	/* Don't report any more data than the device says is valid */
 780	sdev->inquiry_len = min(try_inquiry_len, response_len);
 781
 782	/*
 783	 * XXX Abort if the response length is less than 36? If less than
 784	 * 32, the lookup of the device flags (above) could be invalid,
 785	 * and it would be possible to take an incorrect action - we do
 786	 * not want to hang because of a short INQUIRY. On the flip side,
 787	 * if the device is spun down or becoming ready (and so it gives a
 788	 * short INQUIRY), an abort here prevents any further use of the
 789	 * device, including spin up.
 790	 *
 791	 * On the whole, the best approach seems to be to assume the first
 792	 * 36 bytes are valid no matter what the device says.  That's
 793	 * better than copying < 36 bytes to the inquiry-result buffer
 794	 * and displaying garbage for the Vendor, Product, or Revision
 795	 * strings.
 796	 */
 797	if (sdev->inquiry_len < 36) {
 798		if (!sdev->host->short_inquiry) {
 799			shost_printk(KERN_INFO, sdev->host,
 800				    "scsi scan: INQUIRY result too short (%d),"
 801				    " using 36\n", sdev->inquiry_len);
 802			sdev->host->short_inquiry = 1;
 803		}
 804		sdev->inquiry_len = 36;
 805	}
 806
 807	/*
 808	 * Related to the above issue:
 809	 *
 810	 * XXX Devices (disk or all?) should be sent a TEST UNIT READY,
 811	 * and if not ready, sent a START_STOP to start (maybe spin up) and
 812	 * then send the INQUIRY again, since the INQUIRY can change after
 813	 * a device is initialized.
 814	 *
 815	 * Ideally, start a device if explicitly asked to do so.  This
 816	 * assumes that a device is spun up on power on, spun down on
 817	 * request, and then spun up on request.
 818	 */
 819
 820	/*
 821	 * The scanning code needs to know the scsi_level, even if no
 822	 * device is attached at LUN 0 (SCSI_SCAN_TARGET_PRESENT) so
 823	 * non-zero LUNs can be scanned.
 824	 */
 825	sdev->scsi_level = inq_result[2] & 0x0f;
 826	if (sdev->scsi_level >= 2 ||
 827	    (sdev->scsi_level == 1 && (inq_result[3] & 0x0f) == 1))
 828		sdev->scsi_level++;
 829	sdev->sdev_target->scsi_level = sdev->scsi_level;
 830
 831	/*
 832	 * If SCSI-2 or lower, and if the transport requires it,
 833	 * store the LUN value in CDB[1].
 834	 */
 835	sdev->lun_in_cdb = 0;
 836	if (sdev->scsi_level <= SCSI_2 &&
 837	    sdev->scsi_level != SCSI_UNKNOWN &&
 838	    !sdev->host->no_scsi2_lun_in_cdb)
 839		sdev->lun_in_cdb = 1;
 840
 841	return 0;
 842}
 843
 844/**
 845 * scsi_add_lun - allocate and fully initialze a scsi_device
 846 * @sdev:	holds information to be stored in the new scsi_device
 847 * @inq_result:	holds the result of a previous INQUIRY to the LUN
 848 * @bflags:	black/white list flag
 849 * @async:	1 if this device is being scanned asynchronously
 850 *
 851 * Description:
 852 *     Initialize the scsi_device @sdev.  Optionally set fields based
 853 *     on values in *@bflags.
 854 *
 855 * Return:
 856 *     SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
 857 *     SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
 858 **/
 859static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 860		blist_flags_t *bflags, int async)
 861{
 862	int ret;
 863
 864	/*
 865	 * XXX do not save the inquiry, since it can change underneath us,
 866	 * save just vendor/model/rev.
 867	 *
 868	 * Rather than save it and have an ioctl that retrieves the saved
 869	 * value, have an ioctl that executes the same INQUIRY code used
 870	 * in scsi_probe_lun, let user level programs doing INQUIRY
 871	 * scanning run at their own risk, or supply a user level program
 872	 * that can correctly scan.
 873	 */
 874
 875	/*
 876	 * Copy at least 36 bytes of INQUIRY data, so that we don't
 877	 * dereference unallocated memory when accessing the Vendor,
 878	 * Product, and Revision strings.  Badly behaved devices may set
 879	 * the INQUIRY Additional Length byte to a small value, indicating
 880	 * these strings are invalid, but often they contain plausible data
 881	 * nonetheless.  It doesn't matter if the device sent < 36 bytes
 882	 * total, since scsi_probe_lun() initializes inq_result with 0s.
 883	 */
 884	sdev->inquiry = kmemdup(inq_result,
 885				max_t(size_t, sdev->inquiry_len, 36),
 886				GFP_KERNEL);
 887	if (sdev->inquiry == NULL)
 888		return SCSI_SCAN_NO_RESPONSE;
 889
 890	sdev->vendor = (char *) (sdev->inquiry + 8);
 891	sdev->model = (char *) (sdev->inquiry + 16);
 892	sdev->rev = (char *) (sdev->inquiry + 32);
 893
 894	if (strncmp(sdev->vendor, "ATA     ", 8) == 0) {
 895		/*
 896		 * sata emulation layer device.  This is a hack to work around
 897		 * the SATL power management specifications which state that
 898		 * when the SATL detects the device has gone into standby
 899		 * mode, it shall respond with NOT READY.
 900		 */
 901		sdev->allow_restart = 1;
 902	}
 903
 904	if (*bflags & BLIST_ISROM) {
 905		sdev->type = TYPE_ROM;
 906		sdev->removable = 1;
 907	} else {
 908		sdev->type = (inq_result[0] & 0x1f);
 909		sdev->removable = (inq_result[1] & 0x80) >> 7;
 910
 911		/*
 912		 * some devices may respond with wrong type for
 913		 * well-known logical units. Force well-known type
 914		 * to enumerate them correctly.
 915		 */
 916		if (scsi_is_wlun(sdev->lun) && sdev->type != TYPE_WLUN) {
 917			sdev_printk(KERN_WARNING, sdev,
 918				"%s: correcting incorrect peripheral device type 0x%x for W-LUN 0x%16xhN\n",
 919				__func__, sdev->type, (unsigned int)sdev->lun);
 920			sdev->type = TYPE_WLUN;
 921		}
 922
 923	}
 924
 925	if (sdev->type == TYPE_RBC || sdev->type == TYPE_ROM) {
 926		/* RBC and MMC devices can return SCSI-3 compliance and yet
 927		 * still not support REPORT LUNS, so make them act as
 928		 * BLIST_NOREPORTLUN unless BLIST_REPORTLUN2 is
 929		 * specifically set */
 930		if ((*bflags & BLIST_REPORTLUN2) == 0)
 931			*bflags |= BLIST_NOREPORTLUN;
 932	}
 933
 934	/*
 935	 * For a peripheral qualifier (PQ) value of 1 (001b), the SCSI
 936	 * spec says: The device server is capable of supporting the
 937	 * specified peripheral device type on this logical unit. However,
 938	 * the physical device is not currently connected to this logical
 939	 * unit.
 940	 *
 941	 * The above is vague, as it implies that we could treat 001 and
 942	 * 011 the same. Stay compatible with previous code, and create a
 943	 * scsi_device for a PQ of 1
 944	 *
 945	 * Don't set the device offline here; rather let the upper
 946	 * level drivers eval the PQ to decide whether they should
 947	 * attach. So remove ((inq_result[0] >> 5) & 7) == 1 check.
 948	 */ 
 949
 950	sdev->inq_periph_qual = (inq_result[0] >> 5) & 7;
 951	sdev->lockable = sdev->removable;
 952	sdev->soft_reset = (inq_result[7] & 1) && ((inq_result[3] & 7) == 2);
 953
 954	if (sdev->scsi_level >= SCSI_3 ||
 955			(sdev->inquiry_len > 56 && inq_result[56] & 0x04))
 956		sdev->ppr = 1;
 957	if (inq_result[7] & 0x60)
 958		sdev->wdtr = 1;
 959	if (inq_result[7] & 0x10)
 960		sdev->sdtr = 1;
 961
 962	sdev_printk(KERN_NOTICE, sdev, "%s %.8s %.16s %.4s PQ: %d "
 963			"ANSI: %d%s\n", scsi_device_type(sdev->type),
 964			sdev->vendor, sdev->model, sdev->rev,
 965			sdev->inq_periph_qual, inq_result[2] & 0x07,
 966			(inq_result[3] & 0x0f) == 1 ? " CCS" : "");
 967
 968	if ((sdev->scsi_level >= SCSI_2) && (inq_result[7] & 2) &&
 969	    !(*bflags & BLIST_NOTQ)) {
 970		sdev->tagged_supported = 1;
 971		sdev->simple_tags = 1;
 972	}
 973
 974	/*
 975	 * Some devices (Texel CD ROM drives) have handshaking problems
 976	 * when used with the Seagate controllers. borken is initialized
 977	 * to 1, and then set it to 0 here.
 978	 */
 979	if ((*bflags & BLIST_BORKEN) == 0)
 980		sdev->borken = 0;
 981
 982	if (*bflags & BLIST_NO_ULD_ATTACH)
 983		sdev->no_uld_attach = 1;
 984
 985	/*
 986	 * Apparently some really broken devices (contrary to the SCSI
 987	 * standards) need to be selected without asserting ATN
 988	 */
 989	if (*bflags & BLIST_SELECT_NO_ATN)
 990		sdev->select_no_atn = 1;
 991
 992	/*
 993	 * Maximum 512 sector transfer length
 994	 * broken RA4x00 Compaq Disk Array
 995	 */
 996	if (*bflags & BLIST_MAX_512)
 997		blk_queue_max_hw_sectors(sdev->request_queue, 512);
 998	/*
 999	 * Max 1024 sector transfer length for targets that report incorrect
1000	 * max/optimal lengths and relied on the old block layer safe default
1001	 */
1002	else if (*bflags & BLIST_MAX_1024)
1003		blk_queue_max_hw_sectors(sdev->request_queue, 1024);
1004
1005	/*
1006	 * Some devices may not want to have a start command automatically
1007	 * issued when a device is added.
1008	 */
1009	if (*bflags & BLIST_NOSTARTONADD)
1010		sdev->no_start_on_add = 1;
1011
1012	if (*bflags & BLIST_SINGLELUN)
1013		scsi_target(sdev)->single_lun = 1;
1014
1015	sdev->use_10_for_rw = 1;
1016
1017	/* some devices don't like REPORT SUPPORTED OPERATION CODES
1018	 * and will simply timeout causing sd_mod init to take a very
1019	 * very long time */
1020	if (*bflags & BLIST_NO_RSOC)
1021		sdev->no_report_opcodes = 1;
1022
1023	/* set the device running here so that slave configure
1024	 * may do I/O */
1025	mutex_lock(&sdev->state_mutex);
1026	ret = scsi_device_set_state(sdev, SDEV_RUNNING);
1027	if (ret)
1028		ret = scsi_device_set_state(sdev, SDEV_BLOCK);
1029	mutex_unlock(&sdev->state_mutex);
1030
1031	if (ret) {
1032		sdev_printk(KERN_ERR, sdev,
1033			    "in wrong state %s to complete scan\n",
1034			    scsi_device_state_name(sdev->sdev_state));
1035		return SCSI_SCAN_NO_RESPONSE;
1036	}
1037
1038	if (*bflags & BLIST_NOT_LOCKABLE)
1039		sdev->lockable = 0;
1040
1041	if (*bflags & BLIST_RETRY_HWERROR)
1042		sdev->retry_hwerror = 1;
1043
1044	if (*bflags & BLIST_NO_DIF)
1045		sdev->no_dif = 1;
1046
1047	if (*bflags & BLIST_UNMAP_LIMIT_WS)
1048		sdev->unmap_limit_for_ws = 1;
1049
1050	if (*bflags & BLIST_IGN_MEDIA_CHANGE)
1051		sdev->ignore_media_change = 1;
1052
1053	sdev->eh_timeout = SCSI_DEFAULT_EH_TIMEOUT;
1054
1055	if (*bflags & BLIST_TRY_VPD_PAGES)
1056		sdev->try_vpd_pages = 1;
1057	else if (*bflags & BLIST_SKIP_VPD_PAGES)
1058		sdev->skip_vpd_pages = 1;
1059
1060	if (*bflags & BLIST_NO_VPD_SIZE)
1061		sdev->no_vpd_size = 1;
1062
1063	transport_configure_device(&sdev->sdev_gendev);
1064
1065	if (sdev->host->hostt->slave_configure) {
1066		ret = sdev->host->hostt->slave_configure(sdev);
1067		if (ret) {
1068			/*
1069			 * if LLDD reports slave not present, don't clutter
1070			 * console with alloc failure messages
1071			 */
1072			if (ret != -ENXIO) {
1073				sdev_printk(KERN_ERR, sdev,
1074					"failed to configure device\n");
1075			}
1076			return SCSI_SCAN_NO_RESPONSE;
1077		}
1078
1079		/*
1080		 * The queue_depth is often changed in ->slave_configure.
1081		 * Set up budget map again since memory consumption of
1082		 * the map depends on actual queue depth.
1083		 */
1084		scsi_realloc_sdev_budget_map(sdev, sdev->queue_depth);
1085	}
1086
1087	if (sdev->scsi_level >= SCSI_3)
1088		scsi_attach_vpd(sdev);
1089
1090	scsi_cdl_check(sdev);
1091
1092	sdev->max_queue_depth = sdev->queue_depth;
1093	WARN_ON_ONCE(sdev->max_queue_depth > sdev->budget_map.depth);
1094	sdev->sdev_bflags = *bflags;
1095
1096	/*
1097	 * Ok, the device is now all set up, we can
1098	 * register it and tell the rest of the kernel
1099	 * about it.
1100	 */
1101	if (!async && scsi_sysfs_add_sdev(sdev) != 0)
1102		return SCSI_SCAN_NO_RESPONSE;
1103
1104	return SCSI_SCAN_LUN_PRESENT;
1105}
1106
1107#ifdef CONFIG_SCSI_LOGGING
1108/** 
1109 * scsi_inq_str - print INQUIRY data from min to max index, strip trailing whitespace
1110 * @buf:   Output buffer with at least end-first+1 bytes of space
1111 * @inq:   Inquiry buffer (input)
1112 * @first: Offset of string into inq
1113 * @end:   Index after last character in inq
1114 */
1115static unsigned char *scsi_inq_str(unsigned char *buf, unsigned char *inq,
1116				   unsigned first, unsigned end)
1117{
1118	unsigned term = 0, idx;
1119
1120	for (idx = 0; idx + first < end && idx + first < inq[4] + 5; idx++) {
1121		if (inq[idx+first] > ' ') {
1122			buf[idx] = inq[idx+first];
1123			term = idx+1;
1124		} else {
1125			buf[idx] = ' ';
1126		}
1127	}
1128	buf[term] = 0;
1129	return buf;
1130}
1131#endif
1132
1133/**
1134 * scsi_probe_and_add_lun - probe a LUN, if a LUN is found add it
1135 * @starget:	pointer to target device structure
1136 * @lun:	LUN of target device
1137 * @bflagsp:	store bflags here if not NULL
1138 * @sdevp:	probe the LUN corresponding to this scsi_device
1139 * @rescan:     if not equal to SCSI_SCAN_INITIAL skip some code only
1140 *              needed on first scan
1141 * @hostdata:	passed to scsi_alloc_sdev()
1142 *
1143 * Description:
1144 *     Call scsi_probe_lun, if a LUN with an attached device is found,
1145 *     allocate and set it up by calling scsi_add_lun.
1146 *
1147 * Return:
1148 *
1149 *   - SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
1150 *   - SCSI_SCAN_TARGET_PRESENT: target responded, but no device is
1151 *         attached at the LUN
1152 *   - SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
1153 **/
1154static int scsi_probe_and_add_lun(struct scsi_target *starget,
1155				  u64 lun, blist_flags_t *bflagsp,
1156				  struct scsi_device **sdevp,
1157				  enum scsi_scan_mode rescan,
1158				  void *hostdata)
1159{
1160	struct scsi_device *sdev;
1161	unsigned char *result;
1162	blist_flags_t bflags;
1163	int res = SCSI_SCAN_NO_RESPONSE, result_len = 256;
1164	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1165
1166	/*
1167	 * The rescan flag is used as an optimization, the first scan of a
1168	 * host adapter calls into here with rescan == 0.
1169	 */
1170	sdev = scsi_device_lookup_by_target(starget, lun);
1171	if (sdev) {
1172		if (rescan != SCSI_SCAN_INITIAL || !scsi_device_created(sdev)) {
1173			SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
1174				"scsi scan: device exists on %s\n",
1175				dev_name(&sdev->sdev_gendev)));
1176			if (sdevp)
1177				*sdevp = sdev;
1178			else
1179				scsi_device_put(sdev);
1180
1181			if (bflagsp)
1182				*bflagsp = scsi_get_device_flags(sdev,
1183								 sdev->vendor,
1184								 sdev->model);
1185			return SCSI_SCAN_LUN_PRESENT;
1186		}
1187		scsi_device_put(sdev);
1188	} else
1189		sdev = scsi_alloc_sdev(starget, lun, hostdata);
1190	if (!sdev)
1191		goto out;
1192
1193	result = kmalloc(result_len, GFP_KERNEL);
1194	if (!result)
1195		goto out_free_sdev;
1196
1197	if (scsi_probe_lun(sdev, result, result_len, &bflags))
1198		goto out_free_result;
1199
1200	if (bflagsp)
1201		*bflagsp = bflags;
1202	/*
1203	 * result contains valid SCSI INQUIRY data.
1204	 */
1205	if ((result[0] >> 5) == 3) {
1206		/*
1207		 * For a Peripheral qualifier 3 (011b), the SCSI
1208		 * spec says: The device server is not capable of
1209		 * supporting a physical device on this logical
1210		 * unit.
1211		 *
1212		 * For disks, this implies that there is no
1213		 * logical disk configured at sdev->lun, but there
1214		 * is a target id responding.
1215		 */
1216		SCSI_LOG_SCAN_BUS(2, sdev_printk(KERN_INFO, sdev, "scsi scan:"
1217				   " peripheral qualifier of 3, device not"
1218				   " added\n"))
1219		if (lun == 0) {
1220			SCSI_LOG_SCAN_BUS(1, {
1221				unsigned char vend[9];
1222				unsigned char mod[17];
1223
1224				sdev_printk(KERN_INFO, sdev,
1225					"scsi scan: consider passing scsi_mod."
1226					"dev_flags=%s:%s:0x240 or 0x1000240\n",
1227					scsi_inq_str(vend, result, 8, 16),
1228					scsi_inq_str(mod, result, 16, 32));
1229			});
1230
1231		}
1232
1233		res = SCSI_SCAN_TARGET_PRESENT;
1234		goto out_free_result;
1235	}
1236
1237	/*
1238	 * Some targets may set slight variations of PQ and PDT to signal
1239	 * that no LUN is present, so don't add sdev in these cases.
1240	 * Two specific examples are:
1241	 * 1) NetApp targets: return PQ=1, PDT=0x1f
1242	 * 2) USB UFI: returns PDT=0x1f, with the PQ bits being "reserved"
1243	 *    in the UFI 1.0 spec (we cannot rely on reserved bits).
1244	 *
1245	 * References:
1246	 * 1) SCSI SPC-3, pp. 145-146
1247	 * PQ=1: "A peripheral device having the specified peripheral
1248	 * device type is not connected to this logical unit. However, the
1249	 * device server is capable of supporting the specified peripheral
1250	 * device type on this logical unit."
1251	 * PDT=0x1f: "Unknown or no device type"
1252	 * 2) USB UFI 1.0, p. 20
1253	 * PDT=00h Direct-access device (floppy)
1254	 * PDT=1Fh none (no FDD connected to the requested logical unit)
1255	 */
1256	if (((result[0] >> 5) == 1 || starget->pdt_1f_for_no_lun) &&
1257	    (result[0] & 0x1f) == 0x1f &&
1258	    !scsi_is_wlun(lun)) {
1259		SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
1260					"scsi scan: peripheral device type"
1261					" of 31, no device added\n"));
1262		res = SCSI_SCAN_TARGET_PRESENT;
1263		goto out_free_result;
1264	}
1265
1266	res = scsi_add_lun(sdev, result, &bflags, shost->async_scan);
1267	if (res == SCSI_SCAN_LUN_PRESENT) {
1268		if (bflags & BLIST_KEY) {
1269			sdev->lockable = 0;
1270			scsi_unlock_floptical(sdev, result);
1271		}
1272	}
1273
1274 out_free_result:
1275	kfree(result);
1276 out_free_sdev:
1277	if (res == SCSI_SCAN_LUN_PRESENT) {
1278		if (sdevp) {
1279			if (scsi_device_get(sdev) == 0) {
1280				*sdevp = sdev;
1281			} else {
1282				__scsi_remove_device(sdev);
1283				res = SCSI_SCAN_NO_RESPONSE;
1284			}
1285		}
1286	} else
1287		__scsi_remove_device(sdev);
1288 out:
1289	return res;
1290}
1291
1292/**
1293 * scsi_sequential_lun_scan - sequentially scan a SCSI target
1294 * @starget:	pointer to target structure to scan
1295 * @bflags:	black/white list flag for LUN 0
1296 * @scsi_level: Which version of the standard does this device adhere to
1297 * @rescan:     passed to scsi_probe_add_lun()
1298 *
1299 * Description:
1300 *     Generally, scan from LUN 1 (LUN 0 is assumed to already have been
1301 *     scanned) to some maximum lun until a LUN is found with no device
1302 *     attached. Use the bflags to figure out any oddities.
1303 *
1304 *     Modifies sdevscan->lun.
1305 **/
1306static void scsi_sequential_lun_scan(struct scsi_target *starget,
1307				     blist_flags_t bflags, int scsi_level,
1308				     enum scsi_scan_mode rescan)
1309{
1310	uint max_dev_lun;
1311	u64 sparse_lun, lun;
1312	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1313
1314	SCSI_LOG_SCAN_BUS(3, starget_printk(KERN_INFO, starget,
1315		"scsi scan: Sequential scan\n"));
1316
1317	max_dev_lun = min(max_scsi_luns, shost->max_lun);
1318	/*
1319	 * If this device is known to support sparse multiple units,
1320	 * override the other settings, and scan all of them. Normally,
1321	 * SCSI-3 devices should be scanned via the REPORT LUNS.
1322	 */
1323	if (bflags & BLIST_SPARSELUN) {
1324		max_dev_lun = shost->max_lun;
1325		sparse_lun = 1;
1326	} else
1327		sparse_lun = 0;
1328
1329	/*
1330	 * If less than SCSI_1_CCS, and no special lun scanning, stop
1331	 * scanning; this matches 2.4 behaviour, but could just be a bug
1332	 * (to continue scanning a SCSI_1_CCS device).
1333	 *
1334	 * This test is broken.  We might not have any device on lun0 for
1335	 * a sparselun device, and if that's the case then how would we
1336	 * know the real scsi_level, eh?  It might make sense to just not
1337	 * scan any SCSI_1 device for non-0 luns, but that check would best
1338	 * go into scsi_alloc_sdev() and just have it return null when asked
1339	 * to alloc an sdev for lun > 0 on an already found SCSI_1 device.
1340	 *
1341	if ((sdevscan->scsi_level < SCSI_1_CCS) &&
1342	    ((bflags & (BLIST_FORCELUN | BLIST_SPARSELUN | BLIST_MAX5LUN))
1343	     == 0))
1344		return;
1345	 */
1346	/*
1347	 * If this device is known to support multiple units, override
1348	 * the other settings, and scan all of them.
1349	 */
1350	if (bflags & BLIST_FORCELUN)
1351		max_dev_lun = shost->max_lun;
1352	/*
1353	 * REGAL CDC-4X: avoid hang after LUN 4
1354	 */
1355	if (bflags & BLIST_MAX5LUN)
1356		max_dev_lun = min(5U, max_dev_lun);
1357	/*
1358	 * Do not scan SCSI-2 or lower device past LUN 7, unless
1359	 * BLIST_LARGELUN.
1360	 */
1361	if (scsi_level < SCSI_3 && !(bflags & BLIST_LARGELUN))
1362		max_dev_lun = min(8U, max_dev_lun);
1363	else
1364		max_dev_lun = min(256U, max_dev_lun);
1365
1366	/*
1367	 * We have already scanned LUN 0, so start at LUN 1. Keep scanning
1368	 * until we reach the max, or no LUN is found and we are not
1369	 * sparse_lun.
1370	 */
1371	for (lun = 1; lun < max_dev_lun; ++lun)
1372		if ((scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan,
1373					    NULL) != SCSI_SCAN_LUN_PRESENT) &&
1374		    !sparse_lun)
1375			return;
1376}
1377
1378/**
1379 * scsi_report_lun_scan - Scan using SCSI REPORT LUN results
1380 * @starget: which target
1381 * @bflags: Zero or a mix of BLIST_NOLUN, BLIST_REPORTLUN2, or BLIST_NOREPORTLUN
1382 * @rescan: nonzero if we can skip code only needed on first scan
1383 *
1384 * Description:
1385 *   Fast scanning for modern (SCSI-3) devices by sending a REPORT LUN command.
1386 *   Scan the resulting list of LUNs by calling scsi_probe_and_add_lun.
1387 *
1388 *   If BLINK_REPORTLUN2 is set, scan a target that supports more than 8
1389 *   LUNs even if it's older than SCSI-3.
1390 *   If BLIST_NOREPORTLUN is set, return 1 always.
1391 *   If BLIST_NOLUN is set, return 0 always.
1392 *   If starget->no_report_luns is set, return 1 always.
1393 *
1394 * Return:
1395 *     0: scan completed (or no memory, so further scanning is futile)
1396 *     1: could not scan with REPORT LUN
1397 **/
1398static int scsi_report_lun_scan(struct scsi_target *starget, blist_flags_t bflags,
1399				enum scsi_scan_mode rescan)
1400{
1401	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
1402	unsigned int length;
1403	u64 lun;
1404	unsigned int num_luns;
1405	unsigned int retries;
1406	int result;
1407	struct scsi_lun *lunp, *lun_data;
1408	struct scsi_sense_hdr sshdr;
1409	struct scsi_device *sdev;
1410	struct Scsi_Host *shost = dev_to_shost(&starget->dev);
1411	const struct scsi_exec_args exec_args = {
1412		.sshdr = &sshdr,
1413	};
1414	int ret = 0;
1415
1416	/*
1417	 * Only support SCSI-3 and up devices if BLIST_NOREPORTLUN is not set.
1418	 * Also allow SCSI-2 if BLIST_REPORTLUN2 is set and host adapter does
1419	 * support more than 8 LUNs.
1420	 * Don't attempt if the target doesn't support REPORT LUNS.
1421	 */
1422	if (bflags & BLIST_NOREPORTLUN)
1423		return 1;
1424	if (starget->scsi_level < SCSI_2 &&
1425	    starget->scsi_level != SCSI_UNKNOWN)
1426		return 1;
1427	if (starget->scsi_level < SCSI_3 &&
1428	    (!(bflags & BLIST_REPORTLUN2) || shost->max_lun <= 8))
1429		return 1;
1430	if (bflags & BLIST_NOLUN)
1431		return 0;
1432	if (starget->no_report_luns)
1433		return 1;
1434
1435	if (!(sdev = scsi_device_lookup_by_target(starget, 0))) {
1436		sdev = scsi_alloc_sdev(starget, 0, NULL);
1437		if (!sdev)
1438			return 0;
1439		if (scsi_device_get(sdev)) {
1440			__scsi_remove_device(sdev);
1441			return 0;
1442		}
1443	}
1444
1445	/*
1446	 * Allocate enough to hold the header (the same size as one scsi_lun)
1447	 * plus the number of luns we are requesting.  511 was the default
1448	 * value of the now removed max_report_luns parameter.
1449	 */
1450	length = (511 + 1) * sizeof(struct scsi_lun);
1451retry:
1452	lun_data = kmalloc(length, GFP_KERNEL);
1453	if (!lun_data) {
1454		printk(ALLOC_FAILURE_MSG, __func__);
1455		goto out;
1456	}
1457
1458	scsi_cmd[0] = REPORT_LUNS;
1459
1460	/*
1461	 * bytes 1 - 5: reserved, set to zero.
1462	 */
1463	memset(&scsi_cmd[1], 0, 5);
1464
1465	/*
1466	 * bytes 6 - 9: length of the command.
1467	 */
1468	put_unaligned_be32(length, &scsi_cmd[6]);
1469
1470	scsi_cmd[10] = 0;	/* reserved */
1471	scsi_cmd[11] = 0;	/* control */
1472
1473	/*
1474	 * We can get a UNIT ATTENTION, for example a power on/reset, so
1475	 * retry a few times (like sd.c does for TEST UNIT READY).
1476	 * Experience shows some combinations of adapter/devices get at
1477	 * least two power on/resets.
1478	 *
1479	 * Illegal requests (for devices that do not support REPORT LUNS)
1480	 * should come through as a check condition, and will not generate
1481	 * a retry.
1482	 */
1483	for (retries = 0; retries < 3; retries++) {
1484		SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1485				"scsi scan: Sending REPORT LUNS to (try %d)\n",
1486				retries));
1487
1488		result = scsi_execute_cmd(sdev, scsi_cmd, REQ_OP_DRV_IN,
1489					  lun_data, length,
1490					  SCSI_REPORT_LUNS_TIMEOUT, 3,
1491					  &exec_args);
1492
1493		SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1494				"scsi scan: REPORT LUNS"
1495				" %s (try %d) result 0x%x\n",
1496				result ?  "failed" : "successful",
1497				retries, result));
1498		if (result == 0)
1499			break;
1500		else if (scsi_sense_valid(&sshdr)) {
1501			if (sshdr.sense_key != UNIT_ATTENTION)
1502				break;
1503		}
1504	}
1505
1506	if (result) {
1507		/*
1508		 * The device probably does not support a REPORT LUN command
1509		 */
1510		ret = 1;
1511		goto out_err;
1512	}
1513
1514	/*
1515	 * Get the length from the first four bytes of lun_data.
1516	 */
1517	if (get_unaligned_be32(lun_data->scsi_lun) +
1518	    sizeof(struct scsi_lun) > length) {
1519		length = get_unaligned_be32(lun_data->scsi_lun) +
1520			 sizeof(struct scsi_lun);
1521		kfree(lun_data);
1522		goto retry;
1523	}
1524	length = get_unaligned_be32(lun_data->scsi_lun);
1525
1526	num_luns = (length / sizeof(struct scsi_lun));
1527
1528	SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1529		"scsi scan: REPORT LUN scan\n"));
1530
1531	/*
1532	 * Scan the luns in lun_data. The entry at offset 0 is really
1533	 * the header, so start at 1 and go up to and including num_luns.
1534	 */
1535	for (lunp = &lun_data[1]; lunp <= &lun_data[num_luns]; lunp++) {
1536		lun = scsilun_to_int(lunp);
1537
1538		if (lun > sdev->host->max_lun) {
1539			sdev_printk(KERN_WARNING, sdev,
1540				    "lun%llu has a LUN larger than"
1541				    " allowed by the host adapter\n", lun);
1542		} else {
1543			int res;
1544
1545			res = scsi_probe_and_add_lun(starget,
1546				lun, NULL, NULL, rescan, NULL);
1547			if (res == SCSI_SCAN_NO_RESPONSE) {
1548				/*
1549				 * Got some results, but now none, abort.
1550				 */
1551				sdev_printk(KERN_ERR, sdev,
1552					"Unexpected response"
1553					" from lun %llu while scanning, scan"
1554					" aborted\n", (unsigned long long)lun);
1555				break;
1556			}
1557		}
1558	}
1559
1560 out_err:
1561	kfree(lun_data);
1562 out:
1563	if (scsi_device_created(sdev))
1564		/*
1565		 * the sdev we used didn't appear in the report luns scan
1566		 */
1567		__scsi_remove_device(sdev);
1568	scsi_device_put(sdev);
1569	return ret;
1570}
1571
1572struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
1573				      uint id, u64 lun, void *hostdata)
1574{
1575	struct scsi_device *sdev = ERR_PTR(-ENODEV);
1576	struct device *parent = &shost->shost_gendev;
1577	struct scsi_target *starget;
1578
1579	if (strncmp(scsi_scan_type, "none", 4) == 0)
1580		return ERR_PTR(-ENODEV);
1581
1582	starget = scsi_alloc_target(parent, channel, id);
1583	if (!starget)
1584		return ERR_PTR(-ENOMEM);
1585	scsi_autopm_get_target(starget);
1586
1587	mutex_lock(&shost->scan_mutex);
1588	if (!shost->async_scan)
1589		scsi_complete_async_scans();
1590
1591	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1592		scsi_probe_and_add_lun(starget, lun, NULL, &sdev,
1593				       SCSI_SCAN_RESCAN, hostdata);
1594		scsi_autopm_put_host(shost);
1595	}
1596	mutex_unlock(&shost->scan_mutex);
1597	scsi_autopm_put_target(starget);
1598	/*
1599	 * paired with scsi_alloc_target().  Target will be destroyed unless
1600	 * scsi_probe_and_add_lun made an underlying device visible
1601	 */
1602	scsi_target_reap(starget);
1603	put_device(&starget->dev);
1604
1605	return sdev;
1606}
1607EXPORT_SYMBOL(__scsi_add_device);
1608
1609int scsi_add_device(struct Scsi_Host *host, uint channel,
1610		    uint target, u64 lun)
1611{
1612	struct scsi_device *sdev = 
1613		__scsi_add_device(host, channel, target, lun, NULL);
1614	if (IS_ERR(sdev))
1615		return PTR_ERR(sdev);
1616
1617	scsi_device_put(sdev);
1618	return 0;
1619}
1620EXPORT_SYMBOL(scsi_add_device);
1621
1622int scsi_rescan_device(struct scsi_device *sdev)
1623{
1624	struct device *dev = &sdev->sdev_gendev;
1625	int ret = 0;
1626
1627	device_lock(dev);
1628
1629	/*
1630	 * Bail out if the device or its queue are not running. Otherwise,
1631	 * the rescan may block waiting for commands to be executed, with us
1632	 * holding the device lock. This can result in a potential deadlock
1633	 * in the power management core code when system resume is on-going.
1634	 */
1635	if (sdev->sdev_state != SDEV_RUNNING ||
1636	    blk_queue_pm_only(sdev->request_queue)) {
1637		ret = -EWOULDBLOCK;
1638		goto unlock;
1639	}
1640
1641	scsi_attach_vpd(sdev);
1642	scsi_cdl_check(sdev);
1643
1644	if (sdev->handler && sdev->handler->rescan)
1645		sdev->handler->rescan(sdev);
1646
1647	if (dev->driver && try_module_get(dev->driver->owner)) {
1648		struct scsi_driver *drv = to_scsi_driver(dev->driver);
1649
1650		if (drv->rescan)
1651			drv->rescan(dev);
1652		module_put(dev->driver->owner);
1653	}
1654
1655unlock:
1656	device_unlock(dev);
1657
1658	return ret;
1659}
1660EXPORT_SYMBOL(scsi_rescan_device);
1661
1662static void __scsi_scan_target(struct device *parent, unsigned int channel,
1663		unsigned int id, u64 lun, enum scsi_scan_mode rescan)
1664{
1665	struct Scsi_Host *shost = dev_to_shost(parent);
1666	blist_flags_t bflags = 0;
1667	int res;
1668	struct scsi_target *starget;
1669
1670	if (shost->this_id == id)
1671		/*
1672		 * Don't scan the host adapter
1673		 */
1674		return;
1675
1676	starget = scsi_alloc_target(parent, channel, id);
1677	if (!starget)
1678		return;
1679	scsi_autopm_get_target(starget);
1680
1681	if (lun != SCAN_WILD_CARD) {
1682		/*
1683		 * Scan for a specific host/chan/id/lun.
1684		 */
1685		scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan, NULL);
1686		goto out_reap;
1687	}
1688
1689	/*
1690	 * Scan LUN 0, if there is some response, scan further. Ideally, we
1691	 * would not configure LUN 0 until all LUNs are scanned.
1692	 */
1693	res = scsi_probe_and_add_lun(starget, 0, &bflags, NULL, rescan, NULL);
1694	if (res == SCSI_SCAN_LUN_PRESENT || res == SCSI_SCAN_TARGET_PRESENT) {
1695		if (scsi_report_lun_scan(starget, bflags, rescan) != 0)
1696			/*
1697			 * The REPORT LUN did not scan the target,
1698			 * do a sequential scan.
1699			 */
1700			scsi_sequential_lun_scan(starget, bflags,
1701						 starget->scsi_level, rescan);
1702	}
1703
1704 out_reap:
1705	scsi_autopm_put_target(starget);
1706	/*
1707	 * paired with scsi_alloc_target(): determine if the target has
1708	 * any children at all and if not, nuke it
1709	 */
1710	scsi_target_reap(starget);
1711
1712	put_device(&starget->dev);
1713}
1714
1715/**
1716 * scsi_scan_target - scan a target id, possibly including all LUNs on the target.
1717 * @parent:	host to scan
1718 * @channel:	channel to scan
1719 * @id:		target id to scan
1720 * @lun:	Specific LUN to scan or SCAN_WILD_CARD
1721 * @rescan:	passed to LUN scanning routines; SCSI_SCAN_INITIAL for
1722 *              no rescan, SCSI_SCAN_RESCAN to rescan existing LUNs,
1723 *              and SCSI_SCAN_MANUAL to force scanning even if
1724 *              'scan=manual' is set.
1725 *
1726 * Description:
1727 *     Scan the target id on @parent, @channel, and @id. Scan at least LUN 0,
1728 *     and possibly all LUNs on the target id.
1729 *
1730 *     First try a REPORT LUN scan, if that does not scan the target, do a
1731 *     sequential scan of LUNs on the target id.
1732 **/
1733void scsi_scan_target(struct device *parent, unsigned int channel,
1734		      unsigned int id, u64 lun, enum scsi_scan_mode rescan)
1735{
1736	struct Scsi_Host *shost = dev_to_shost(parent);
1737
1738	if (strncmp(scsi_scan_type, "none", 4) == 0)
1739		return;
1740
1741	if (rescan != SCSI_SCAN_MANUAL &&
1742	    strncmp(scsi_scan_type, "manual", 6) == 0)
1743		return;
1744
1745	mutex_lock(&shost->scan_mutex);
1746	if (!shost->async_scan)
1747		scsi_complete_async_scans();
1748
1749	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1750		__scsi_scan_target(parent, channel, id, lun, rescan);
1751		scsi_autopm_put_host(shost);
1752	}
1753	mutex_unlock(&shost->scan_mutex);
1754}
1755EXPORT_SYMBOL(scsi_scan_target);
1756
1757static void scsi_scan_channel(struct Scsi_Host *shost, unsigned int channel,
1758			      unsigned int id, u64 lun,
1759			      enum scsi_scan_mode rescan)
1760{
1761	uint order_id;
1762
1763	if (id == SCAN_WILD_CARD)
1764		for (id = 0; id < shost->max_id; ++id) {
1765			/*
1766			 * XXX adapter drivers when possible (FCP, iSCSI)
1767			 * could modify max_id to match the current max,
1768			 * not the absolute max.
1769			 *
1770			 * XXX add a shost id iterator, so for example,
1771			 * the FC ID can be the same as a target id
1772			 * without a huge overhead of sparse id's.
1773			 */
1774			if (shost->reverse_ordering)
1775				/*
1776				 * Scan from high to low id.
1777				 */
1778				order_id = shost->max_id - id - 1;
1779			else
1780				order_id = id;
1781			__scsi_scan_target(&shost->shost_gendev, channel,
1782					order_id, lun, rescan);
1783		}
1784	else
1785		__scsi_scan_target(&shost->shost_gendev, channel,
1786				id, lun, rescan);
1787}
1788
1789int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel,
1790			    unsigned int id, u64 lun,
1791			    enum scsi_scan_mode rescan)
1792{
1793	SCSI_LOG_SCAN_BUS(3, shost_printk (KERN_INFO, shost,
1794		"%s: <%u:%u:%llu>\n",
1795		__func__, channel, id, lun));
1796
1797	if (((channel != SCAN_WILD_CARD) && (channel > shost->max_channel)) ||
1798	    ((id != SCAN_WILD_CARD) && (id >= shost->max_id)) ||
1799	    ((lun != SCAN_WILD_CARD) && (lun >= shost->max_lun)))
1800		return -EINVAL;
1801
1802	mutex_lock(&shost->scan_mutex);
1803	if (!shost->async_scan)
1804		scsi_complete_async_scans();
1805
1806	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1807		if (channel == SCAN_WILD_CARD)
1808			for (channel = 0; channel <= shost->max_channel;
1809			     channel++)
1810				scsi_scan_channel(shost, channel, id, lun,
1811						  rescan);
1812		else
1813			scsi_scan_channel(shost, channel, id, lun, rescan);
1814		scsi_autopm_put_host(shost);
1815	}
1816	mutex_unlock(&shost->scan_mutex);
1817
1818	return 0;
1819}
1820
1821static void scsi_sysfs_add_devices(struct Scsi_Host *shost)
1822{
1823	struct scsi_device *sdev;
1824	shost_for_each_device(sdev, shost) {
1825		/* target removed before the device could be added */
1826		if (sdev->sdev_state == SDEV_DEL)
1827			continue;
1828		/* If device is already visible, skip adding it to sysfs */
1829		if (sdev->is_visible)
1830			continue;
1831		if (!scsi_host_scan_allowed(shost) ||
1832		    scsi_sysfs_add_sdev(sdev) != 0)
1833			__scsi_remove_device(sdev);
1834	}
1835}
1836
1837/**
1838 * scsi_prep_async_scan - prepare for an async scan
1839 * @shost: the host which will be scanned
1840 * Returns: a cookie to be passed to scsi_finish_async_scan()
1841 *
1842 * Tells the midlayer this host is going to do an asynchronous scan.
1843 * It reserves the host's position in the scanning list and ensures
1844 * that other asynchronous scans started after this one won't affect the
1845 * ordering of the discovered devices.
1846 */
1847static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost)
1848{
1849	struct async_scan_data *data = NULL;
1850	unsigned long flags;
1851
1852	if (strncmp(scsi_scan_type, "sync", 4) == 0)
1853		return NULL;
1854
1855	mutex_lock(&shost->scan_mutex);
1856	if (shost->async_scan) {
1857		shost_printk(KERN_DEBUG, shost, "%s called twice\n", __func__);
1858		goto err;
1859	}
1860
1861	data = kmalloc(sizeof(*data), GFP_KERNEL);
1862	if (!data)
1863		goto err;
1864	data->shost = scsi_host_get(shost);
1865	if (!data->shost)
1866		goto err;
1867	init_completion(&data->prev_finished);
1868
1869	spin_lock_irqsave(shost->host_lock, flags);
1870	shost->async_scan = 1;
1871	spin_unlock_irqrestore(shost->host_lock, flags);
1872	mutex_unlock(&shost->scan_mutex);
1873
1874	spin_lock(&async_scan_lock);
1875	if (list_empty(&scanning_hosts))
1876		complete(&data->prev_finished);
1877	list_add_tail(&data->list, &scanning_hosts);
1878	spin_unlock(&async_scan_lock);
1879
1880	return data;
1881
1882 err:
1883	mutex_unlock(&shost->scan_mutex);
1884	kfree(data);
1885	return NULL;
1886}
1887
1888/**
1889 * scsi_finish_async_scan - asynchronous scan has finished
1890 * @data: cookie returned from earlier call to scsi_prep_async_scan()
1891 *
1892 * All the devices currently attached to this host have been found.
1893 * This function announces all the devices it has found to the rest
1894 * of the system.
1895 */
1896static void scsi_finish_async_scan(struct async_scan_data *data)
1897{
1898	struct Scsi_Host *shost;
1899	unsigned long flags;
1900
1901	if (!data)
1902		return;
1903
1904	shost = data->shost;
1905
1906	mutex_lock(&shost->scan_mutex);
1907
1908	if (!shost->async_scan) {
1909		shost_printk(KERN_INFO, shost, "%s called twice\n", __func__);
1910		dump_stack();
1911		mutex_unlock(&shost->scan_mutex);
1912		return;
1913	}
1914
1915	wait_for_completion(&data->prev_finished);
1916
1917	scsi_sysfs_add_devices(shost);
1918
1919	spin_lock_irqsave(shost->host_lock, flags);
1920	shost->async_scan = 0;
1921	spin_unlock_irqrestore(shost->host_lock, flags);
1922
1923	mutex_unlock(&shost->scan_mutex);
1924
1925	spin_lock(&async_scan_lock);
1926	list_del(&data->list);
1927	if (!list_empty(&scanning_hosts)) {
1928		struct async_scan_data *next = list_entry(scanning_hosts.next,
1929				struct async_scan_data, list);
1930		complete(&next->prev_finished);
1931	}
1932	spin_unlock(&async_scan_lock);
1933
1934	scsi_autopm_put_host(shost);
1935	scsi_host_put(shost);
1936	kfree(data);
1937}
1938
1939static void do_scsi_scan_host(struct Scsi_Host *shost)
1940{
1941	if (shost->hostt->scan_finished) {
1942		unsigned long start = jiffies;
1943		if (shost->hostt->scan_start)
1944			shost->hostt->scan_start(shost);
1945
1946		while (!shost->hostt->scan_finished(shost, jiffies - start))
1947			msleep(10);
1948	} else {
1949		scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD,
1950				SCAN_WILD_CARD, SCSI_SCAN_INITIAL);
1951	}
1952}
1953
1954static void do_scan_async(void *_data, async_cookie_t c)
1955{
1956	struct async_scan_data *data = _data;
1957	struct Scsi_Host *shost = data->shost;
1958
1959	do_scsi_scan_host(shost);
1960	scsi_finish_async_scan(data);
1961}
1962
1963/**
1964 * scsi_scan_host - scan the given adapter
1965 * @shost:	adapter to scan
1966 **/
1967void scsi_scan_host(struct Scsi_Host *shost)
1968{
1969	struct async_scan_data *data;
1970
1971	if (strncmp(scsi_scan_type, "none", 4) == 0 ||
1972	    strncmp(scsi_scan_type, "manual", 6) == 0)
1973		return;
1974	if (scsi_autopm_get_host(shost) < 0)
1975		return;
1976
1977	data = scsi_prep_async_scan(shost);
1978	if (!data) {
1979		do_scsi_scan_host(shost);
1980		scsi_autopm_put_host(shost);
1981		return;
1982	}
1983
1984	/* register with the async subsystem so wait_for_device_probe()
1985	 * will flush this work
1986	 */
1987	async_schedule(do_scan_async, data);
1988
1989	/* scsi_autopm_put_host(shost) is called in scsi_finish_async_scan() */
1990}
1991EXPORT_SYMBOL(scsi_scan_host);
1992
1993void scsi_forget_host(struct Scsi_Host *shost)
1994{
1995	struct scsi_device *sdev;
1996	unsigned long flags;
1997
1998 restart:
1999	spin_lock_irqsave(shost->host_lock, flags);
2000	list_for_each_entry(sdev, &shost->__devices, siblings) {
2001		if (sdev->sdev_state == SDEV_DEL)
2002			continue;
2003		spin_unlock_irqrestore(shost->host_lock, flags);
2004		__scsi_remove_device(sdev);
2005		goto restart;
2006	}
2007	spin_unlock_irqrestore(shost->host_lock, flags);
2008}
2009