scsi_scan.c

   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 <linux/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		scoped_guard(spinlock, &async_scan_lock)
 155			if (list_empty(&scanning_hosts))
 156				return 0;
 157		/* If we can't get memory immediately, that's OK.  Just
 158		 * sleep a little.  Even if we never get memory, the async
 159		 * scans will finish eventually.
 160		 */
 161		data = kmalloc(sizeof(*data), GFP_KERNEL);
 162		if (!data)
 163			msleep(1);
 164	} while (!data);
 165
 166	data->shost = NULL;
 167	init_completion(&data->prev_finished);
 168
 169	spin_lock(&async_scan_lock);
 170	/* Check that there's still somebody else on the list */
 171	if (list_empty(&scanning_hosts))
 172		goto done;
 173	list_add_tail(&data->list, &scanning_hosts);
 174	spin_unlock(&async_scan_lock);
 175
 176	printk(KERN_INFO "scsi: waiting for bus probes to complete ...\n");
 177	wait_for_completion(&data->prev_finished);
 178
 179	spin_lock(&async_scan_lock);
 180	list_del(&data->list);
 181	if (!list_empty(&scanning_hosts)) {
 182		struct async_scan_data *next = list_entry(scanning_hosts.next,
 183				struct async_scan_data, list);
 184		complete(&next->prev_finished);
 185	}
 186 done:
 187	spin_unlock(&async_scan_lock);
 188
 189	kfree(data);
 190	return 0;
 191}
 192
 193/**
 194 * scsi_unlock_floptical - unlock device via a special MODE SENSE command
 195 * @sdev:	scsi device to send command to
 196 * @result:	area to store the result of the MODE SENSE
 197 *
 198 * Description:
 199 *     Send a vendor specific MODE SENSE (not a MODE SELECT) command.
 200 *     Called for BLIST_KEY devices.
 201 **/
 202static void scsi_unlock_floptical(struct scsi_device *sdev,
 203				  unsigned char *result)
 204{
 205	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
 206
 207	sdev_printk(KERN_NOTICE, sdev, "unlocking floptical drive\n");
 208	scsi_cmd[0] = MODE_SENSE;
 209	scsi_cmd[1] = 0;
 210	scsi_cmd[2] = 0x2e;
 211	scsi_cmd[3] = 0;
 212	scsi_cmd[4] = 0x2a;     /* size */
 213	scsi_cmd[5] = 0;
 214	scsi_execute_cmd(sdev, scsi_cmd, REQ_OP_DRV_IN, result, 0x2a,
 215			 SCSI_TIMEOUT, 3, NULL);
 216}
 217
 218static int scsi_realloc_sdev_budget_map(struct scsi_device *sdev,
 219					unsigned int depth)
 220{
 221	int new_shift = sbitmap_calculate_shift(depth);
 222	bool need_alloc = !sdev->budget_map.map;
 223	bool need_free = false;
 224	unsigned int memflags;
 225	int ret;
 226	struct sbitmap sb_backup;
 227
 228	depth = min_t(unsigned int, depth, scsi_device_max_queue_depth(sdev));
 229
 230	/*
 231	 * realloc if new shift is calculated, which is caused by setting
 232	 * up one new default queue depth after calling ->sdev_configure
 233	 */
 234	if (!need_alloc && new_shift != sdev->budget_map.shift)
 235		need_alloc = need_free = true;
 236
 237	if (!need_alloc)
 238		return 0;
 239
 240	/*
 241	 * Request queue has to be frozen for reallocating budget map,
 242	 * and here disk isn't added yet, so freezing is pretty fast
 243	 */
 244	if (need_free) {
 245		memflags = blk_mq_freeze_queue(sdev->request_queue);
 246		sb_backup = sdev->budget_map;
 247	}
 248	ret = sbitmap_init_node(&sdev->budget_map,
 249				scsi_device_max_queue_depth(sdev),
 250				new_shift, GFP_NOIO,
 251				sdev->request_queue->node, false, true);
 252	if (!ret)
 253		sbitmap_resize(&sdev->budget_map, depth);
 254
 255	if (need_free) {
 256		if (ret)
 257			sdev->budget_map = sb_backup;
 258		else
 259			sbitmap_free(&sb_backup);
 260		ret = 0;
 261		blk_mq_unfreeze_queue(sdev->request_queue, memflags);
 262	}
 263	return ret;
 264}
 265
 266/**
 267 * scsi_alloc_sdev - allocate and setup a scsi_Device
 268 * @starget: which target to allocate a &scsi_device for
 269 * @lun: which lun
 270 * @hostdata: usually NULL and set by ->sdev_init instead
 271 *
 272 * Description:
 273 *     Allocate, initialize for io, and return a pointer to a scsi_Device.
 274 *     Stores the @shost, @channel, @id, and @lun in the scsi_Device, and
 275 *     adds scsi_Device to the appropriate list.
 276 *
 277 * Return value:
 278 *     scsi_Device pointer, or NULL on failure.
 279 **/
 280static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
 281					   u64 lun, void *hostdata)
 282{
 283	unsigned int depth;
 284	struct scsi_device *sdev;
 285	struct request_queue *q;
 286	int display_failure_msg = 1, ret;
 287	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 288	struct queue_limits lim;
 289
 290	sdev = kzalloc(sizeof(*sdev) + shost->transportt->device_size,
 291		       GFP_KERNEL);
 292	if (!sdev)
 293		goto out;
 294
 295	sdev->vendor = scsi_null_device_strs;
 296	sdev->model = scsi_null_device_strs;
 297	sdev->rev = scsi_null_device_strs;
 298	sdev->host = shost;
 299	sdev->queue_ramp_up_period = SCSI_DEFAULT_RAMP_UP_PERIOD;
 300	sdev->id = starget->id;
 301	sdev->lun = lun;
 302	sdev->channel = starget->channel;
 303	mutex_init(&sdev->state_mutex);
 304	sdev->sdev_state = SDEV_CREATED;
 305	INIT_LIST_HEAD(&sdev->siblings);
 306	INIT_LIST_HEAD(&sdev->same_target_siblings);
 307	INIT_LIST_HEAD(&sdev->starved_entry);
 308	INIT_LIST_HEAD(&sdev->event_list);
 309	spin_lock_init(&sdev->list_lock);
 310	mutex_init(&sdev->inquiry_mutex);
 311	INIT_WORK(&sdev->event_work, scsi_evt_thread);
 312	INIT_WORK(&sdev->requeue_work, scsi_requeue_run_queue);
 313
 314	sdev->sdev_gendev.parent = get_device(&starget->dev);
 315	sdev->sdev_target = starget;
 316
 317	/* usually NULL and set by ->sdev_init instead */
 318	sdev->hostdata = hostdata;
 319
 320	/* if the device needs this changing, it may do so in the
 321	 * sdev_configure function */
 322	sdev->max_device_blocked = SCSI_DEFAULT_DEVICE_BLOCKED;
 323
 324	/*
 325	 * Some low level driver could use device->type
 326	 */
 327	sdev->type = -1;
 328
 329	/*
 330	 * Assume that the device will have handshaking problems,
 331	 * and then fix this field later if it turns out it
 332	 * doesn't
 333	 */
 334	sdev->borken = 1;
 335
 336	sdev->sg_reserved_size = INT_MAX;
 337
 338	scsi_init_limits(shost, &lim);
 339	q = blk_mq_alloc_queue(&sdev->host->tag_set, &lim, sdev);
 340	if (IS_ERR(q)) {
 341		/* release fn is set up in scsi_sysfs_device_initialise, so
 342		 * have to free and put manually here */
 343		put_device(&starget->dev);
 344		kfree(sdev);
 345		goto out;
 346	}
 347	kref_get(&sdev->host->tagset_refcnt);
 348	sdev->request_queue = q;
 349
 350	scsi_sysfs_device_initialize(sdev);
 351
 352	if (scsi_device_is_pseudo_dev(sdev))
 353		return sdev;
 354
 355	depth = sdev->host->cmd_per_lun ?: 1;
 356
 357	/*
 358	 * Use .can_queue as budget map's depth because we have to
 359	 * support adjusting queue depth from sysfs. Meantime use
 360	 * default device queue depth to figure out sbitmap shift
 361	 * since we use this queue depth most of times.
 362	 */
 363	if (scsi_realloc_sdev_budget_map(sdev, depth))
 364		goto out_device_destroy;
 365
 366	scsi_change_queue_depth(sdev, depth);
 367
 368	if (shost->hostt->sdev_init) {
 369		ret = shost->hostt->sdev_init(sdev);
 370		if (ret) {
 371			/*
 372			 * if LLDD reports slave not present, don't clutter
 373			 * console with alloc failure messages
 374			 */
 375			if (ret == -ENXIO)
 376				display_failure_msg = 0;
 377			goto out_device_destroy;
 378		}
 379	}
 380
 381	return sdev;
 382
 383out_device_destroy:
 384	__scsi_remove_device(sdev);
 385out:
 386	if (display_failure_msg)
 387		printk(ALLOC_FAILURE_MSG, __func__);
 388	return NULL;
 389}
 390
 391static void scsi_target_destroy(struct scsi_target *starget)
 392{
 393	struct device *dev = &starget->dev;
 394	struct Scsi_Host *shost = dev_to_shost(dev->parent);
 395	unsigned long flags;
 396
 397	BUG_ON(starget->state == STARGET_DEL);
 398	starget->state = STARGET_DEL;
 399	transport_destroy_device(dev);
 400	spin_lock_irqsave(shost->host_lock, flags);
 401	if (shost->hostt->target_destroy)
 402		shost->hostt->target_destroy(starget);
 403	list_del_init(&starget->siblings);
 404	spin_unlock_irqrestore(shost->host_lock, flags);
 405	put_device(dev);
 406}
 407
 408static void scsi_target_dev_release(struct device *dev)
 409{
 410	struct device *parent = dev->parent;
 411	struct scsi_target *starget = to_scsi_target(dev);
 412
 413	kfree(starget);
 414	put_device(parent);
 415}
 416
 417static const struct device_type scsi_target_type = {
 418	.name =		"scsi_target",
 419	.release =	scsi_target_dev_release,
 420};
 421
 422int scsi_is_target_device(const struct device *dev)
 423{
 424	return dev->type == &scsi_target_type;
 425}
 426EXPORT_SYMBOL(scsi_is_target_device);
 427
 428static struct scsi_target *__scsi_find_target(struct device *parent,
 429					      int channel, uint id)
 430{
 431	struct scsi_target *starget, *found_starget = NULL;
 432	struct Scsi_Host *shost = dev_to_shost(parent);
 433	/*
 434	 * Search for an existing target for this sdev.
 435	 */
 436	list_for_each_entry(starget, &shost->__targets, siblings) {
 437		if (starget->id == id &&
 438		    starget->channel == channel) {
 439			found_starget = starget;
 440			break;
 441		}
 442	}
 443	if (found_starget)
 444		get_device(&found_starget->dev);
 445
 446	return found_starget;
 447}
 448
 449/**
 450 * scsi_target_reap_ref_release - remove target from visibility
 451 * @kref: the reap_ref in the target being released
 452 *
 453 * Called on last put of reap_ref, which is the indication that no device
 454 * under this target is visible anymore, so render the target invisible in
 455 * sysfs.  Note: we have to be in user context here because the target reaps
 456 * should be done in places where the scsi device visibility is being removed.
 457 */
 458static void scsi_target_reap_ref_release(struct kref *kref)
 459{
 460	struct scsi_target *starget
 461		= container_of(kref, struct scsi_target, reap_ref);
 462
 463	/*
 464	 * if we get here and the target is still in a CREATED state that
 465	 * means it was allocated but never made visible (because a scan
 466	 * turned up no LUNs), so don't call device_del() on it.
 467	 */
 468	if ((starget->state != STARGET_CREATED) &&
 469	    (starget->state != STARGET_CREATED_REMOVE)) {
 470		transport_remove_device(&starget->dev);
 471		device_del(&starget->dev);
 472	}
 473	scsi_target_destroy(starget);
 474}
 475
 476static void scsi_target_reap_ref_put(struct scsi_target *starget)
 477{
 478	kref_put(&starget->reap_ref, scsi_target_reap_ref_release);
 479}
 480
 481/**
 482 * scsi_alloc_target - allocate a new or find an existing target
 483 * @parent:	parent of the target (need not be a scsi host)
 484 * @channel:	target channel number (zero if no channels)
 485 * @id:		target id number
 486 *
 487 * Return an existing target if one exists, provided it hasn't already
 488 * gone into STARGET_DEL state, otherwise allocate a new target.
 489 *
 490 * The target is returned with an incremented reference, so the caller
 491 * is responsible for both reaping and doing a last put
 492 */
 493static struct scsi_target *scsi_alloc_target(struct device *parent,
 494					     int channel, uint id)
 495{
 496	struct Scsi_Host *shost = dev_to_shost(parent);
 497	struct device *dev = NULL;
 498	unsigned long flags;
 499	const int size = sizeof(struct scsi_target)
 500		+ shost->transportt->target_size;
 501	struct scsi_target *starget;
 502	struct scsi_target *found_target;
 503	int error, ref_got;
 504
 505	starget = kzalloc(size, GFP_KERNEL);
 506	if (!starget) {
 507		printk(KERN_ERR "%s: allocation failure\n", __func__);
 508		return NULL;
 509	}
 510	dev = &starget->dev;
 511	device_initialize(dev);
 512	kref_init(&starget->reap_ref);
 513	dev->parent = get_device(parent);
 514	dev_set_name(dev, "target%d:%d:%d", shost->host_no, channel, id);
 515	dev->bus = &scsi_bus_type;
 516	dev->type = &scsi_target_type;
 517	scsi_enable_async_suspend(dev);
 518	starget->id = id;
 519	starget->channel = channel;
 520	starget->can_queue = 0;
 521	INIT_LIST_HEAD(&starget->siblings);
 522	INIT_LIST_HEAD(&starget->devices);
 523	starget->state = STARGET_CREATED;
 524	starget->scsi_level = SCSI_2;
 525	starget->max_target_blocked = SCSI_DEFAULT_TARGET_BLOCKED;
 526 retry:
 527	spin_lock_irqsave(shost->host_lock, flags);
 528
 529	found_target = __scsi_find_target(parent, channel, id);
 530	if (found_target)
 531		goto found;
 532
 533	list_add_tail(&starget->siblings, &shost->__targets);
 534	spin_unlock_irqrestore(shost->host_lock, flags);
 535	/* allocate and add */
 536	transport_setup_device(dev);
 537	if (shost->hostt->target_alloc) {
 538		error = shost->hostt->target_alloc(starget);
 539
 540		if(error) {
 541			if (error != -ENXIO)
 542				dev_err(dev, "target allocation failed, error %d\n", error);
 543			/* don't want scsi_target_reap to do the final
 544			 * put because it will be under the host lock */
 545			scsi_target_destroy(starget);
 546			return NULL;
 547		}
 548	}
 549	get_device(dev);
 550
 551	return starget;
 552
 553 found:
 554	/*
 555	 * release routine already fired if kref is zero, so if we can still
 556	 * take the reference, the target must be alive.  If we can't, it must
 557	 * be dying and we need to wait for a new target
 558	 */
 559	ref_got = kref_get_unless_zero(&found_target->reap_ref);
 560
 561	spin_unlock_irqrestore(shost->host_lock, flags);
 562	if (ref_got) {
 563		put_device(dev);
 564		return found_target;
 565	}
 566	/*
 567	 * Unfortunately, we found a dying target; need to wait until it's
 568	 * dead before we can get a new one.  There is an anomaly here.  We
 569	 * *should* call scsi_target_reap() to balance the kref_get() of the
 570	 * reap_ref above.  However, since the target being released, it's
 571	 * already invisible and the reap_ref is irrelevant.  If we call
 572	 * scsi_target_reap() we might spuriously do another device_del() on
 573	 * an already invisible target.
 574	 */
 575	put_device(&found_target->dev);
 576	/*
 577	 * length of time is irrelevant here, we just want to yield the CPU
 578	 * for a tick to avoid busy waiting for the target to die.
 579	 */
 580	msleep(1);
 581	goto retry;
 582}
 583
 584/**
 585 * scsi_target_reap - check to see if target is in use and destroy if not
 586 * @starget: target to be checked
 587 *
 588 * This is used after removing a LUN or doing a last put of the target
 589 * it checks atomically that nothing is using the target and removes
 590 * it if so.
 591 */
 592void scsi_target_reap(struct scsi_target *starget)
 593{
 594	/*
 595	 * serious problem if this triggers: STARGET_DEL is only set in the if
 596	 * the reap_ref drops to zero, so we're trying to do another final put
 597	 * on an already released kref
 598	 */
 599	BUG_ON(starget->state == STARGET_DEL);
 600	scsi_target_reap_ref_put(starget);
 601}
 602
 603/**
 604 * scsi_sanitize_inquiry_string - remove non-graphical chars from an
 605 *                                INQUIRY result string
 606 * @s: INQUIRY result string to sanitize
 607 * @len: length of the string
 608 *
 609 * Description:
 610 *	The SCSI spec says that INQUIRY vendor, product, and revision
 611 *	strings must consist entirely of graphic ASCII characters,
 612 *	padded on the right with spaces.  Since not all devices obey
 613 *	this rule, we will replace non-graphic or non-ASCII characters
 614 *	with spaces.  Exception: a NUL character is interpreted as a
 615 *	string terminator, so all the following characters are set to
 616 *	spaces.
 617 **/
 618void scsi_sanitize_inquiry_string(unsigned char *s, int len)
 619{
 620	int terminated = 0;
 621
 622	for (; len > 0; (--len, ++s)) {
 623		if (*s == 0)
 624			terminated = 1;
 625		if (terminated || *s < 0x20 || *s > 0x7e)
 626			*s = ' ';
 627	}
 628}
 629EXPORT_SYMBOL(scsi_sanitize_inquiry_string);
 630
 631
 632/**
 633 * scsi_probe_lun - probe a single LUN using a SCSI INQUIRY
 634 * @sdev:	scsi_device to probe
 635 * @inq_result:	area to store the INQUIRY result
 636 * @result_len: len of inq_result
 637 * @bflags:	store any bflags found here
 638 *
 639 * Description:
 640 *     Probe the lun associated with @req using a standard SCSI INQUIRY;
 641 *
 642 *     If the INQUIRY is successful, zero is returned and the
 643 *     INQUIRY data is in @inq_result; the scsi_level and INQUIRY length
 644 *     are copied to the scsi_device any flags value is stored in *@bflags.
 645 **/
 646static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result,
 647			  int result_len, blist_flags_t *bflags)
 648{
 649	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
 650	int first_inquiry_len, try_inquiry_len, next_inquiry_len;
 651	int response_len = 0;
 652	int pass, count, result, resid;
 653	struct scsi_failure failure_defs[] = {
 654		/*
 655		 * not-ready to ready transition [asc/ascq=0x28/0x0] or
 656		 * power-on, reset [asc/ascq=0x29/0x0], continue. INQUIRY
 657		 * should not yield UNIT_ATTENTION but many buggy devices do
 658		 * so anyway.
 659		 */
 660		{
 661			.sense = UNIT_ATTENTION,
 662			.asc = 0x28,
 663			.result = SAM_STAT_CHECK_CONDITION,
 664		},
 665		{
 666			.sense = UNIT_ATTENTION,
 667			.asc = 0x29,
 668			.result = SAM_STAT_CHECK_CONDITION,
 669		},
 670		{
 671			.allowed = 1,
 672			.result = DID_TIME_OUT << 16,
 673		},
 674		{}
 675	};
 676	struct scsi_failures failures = {
 677		.total_allowed = 3,
 678		.failure_definitions = failure_defs,
 679	};
 680	const struct scsi_exec_args exec_args = {
 681		.resid = &resid,
 682		.failures = &failures,
 683	};
 684
 685	*bflags = 0;
 686
 687	/* Perform up to 3 passes.  The first pass uses a conservative
 688	 * transfer length of 36 unless sdev->inquiry_len specifies a
 689	 * different value. */
 690	first_inquiry_len = sdev->inquiry_len ? sdev->inquiry_len : 36;
 691	try_inquiry_len = first_inquiry_len;
 692	pass = 1;
 693
 694 next_pass:
 695	SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
 696				"scsi scan: INQUIRY pass %d length %d\n",
 697				pass, try_inquiry_len));
 698
 699	/* Each pass gets up to three chances to ignore Unit Attention */
 700	scsi_failures_reset_retries(&failures);
 701
 702	for (count = 0; count < 3; ++count) {
 703		memset(scsi_cmd, 0, 6);
 704		scsi_cmd[0] = INQUIRY;
 705		scsi_cmd[4] = (unsigned char) try_inquiry_len;
 706
 707		memset(inq_result, 0, try_inquiry_len);
 708
 709		result = scsi_execute_cmd(sdev,  scsi_cmd, REQ_OP_DRV_IN,
 710					  inq_result, try_inquiry_len,
 711					  HZ / 2 + HZ * scsi_inq_timeout, 3,
 712					  &exec_args);
 713
 714		SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
 715				"scsi scan: INQUIRY %s with code 0x%x\n",
 716				result ? "failed" : "successful", result));
 717
 718		if (result == 0) {
 719			/*
 720			 * if nothing was transferred, we try
 721			 * again. It's a workaround for some USB
 722			 * devices.
 723			 */
 724			if (resid == try_inquiry_len)
 725				continue;
 726		}
 727		break;
 728	}
 729
 730	if (result == 0) {
 731		scsi_sanitize_inquiry_string(&inq_result[8], 8);
 732		scsi_sanitize_inquiry_string(&inq_result[16], 16);
 733		scsi_sanitize_inquiry_string(&inq_result[32], 4);
 734
 735		response_len = inq_result[4] + 5;
 736		if (response_len > 255)
 737			response_len = first_inquiry_len;	/* sanity */
 738
 739		/*
 740		 * Get any flags for this device.
 741		 *
 742		 * XXX add a bflags to scsi_device, and replace the
 743		 * corresponding bit fields in scsi_device, so bflags
 744		 * need not be passed as an argument.
 745		 */
 746		*bflags = scsi_get_device_flags(sdev, &inq_result[8],
 747				&inq_result[16]);
 748
 749		/* When the first pass succeeds we gain information about
 750		 * what larger transfer lengths might work. */
 751		if (pass == 1) {
 752			if (BLIST_INQUIRY_36 & *bflags)
 753				next_inquiry_len = 36;
 754			/*
 755			 * LLD specified a maximum sdev->inquiry_len
 756			 * but device claims it has more data. Capping
 757			 * the length only makes sense for legacy
 758			 * devices. If a device supports SPC-4 (2014)
 759			 * or newer, assume that it is safe to ask for
 760			 * as much as the device says it supports.
 761			 */
 762			else if (sdev->inquiry_len &&
 763				 response_len > sdev->inquiry_len &&
 764				 (inq_result[2] & 0x7) < 6) /* SPC-4 */
 765				next_inquiry_len = sdev->inquiry_len;
 766			else
 767				next_inquiry_len = response_len;
 768
 769			/* If more data is available perform the second pass */
 770			if (next_inquiry_len > try_inquiry_len) {
 771				try_inquiry_len = next_inquiry_len;
 772				pass = 2;
 773				goto next_pass;
 774			}
 775		}
 776
 777	} else if (pass == 2) {
 778		sdev_printk(KERN_INFO, sdev,
 779			    "scsi scan: %d byte inquiry failed.  "
 780			    "Consider BLIST_INQUIRY_36 for this device\n",
 781			    try_inquiry_len);
 782
 783		/* If this pass failed, the third pass goes back and transfers
 784		 * the same amount as we successfully got in the first pass. */
 785		try_inquiry_len = first_inquiry_len;
 786		pass = 3;
 787		goto next_pass;
 788	}
 789
 790	/* If the last transfer attempt got an error, assume the
 791	 * peripheral doesn't exist or is dead. */
 792	if (result)
 793		return -EIO;
 794
 795	/* Don't report any more data than the device says is valid */
 796	sdev->inquiry_len = min(try_inquiry_len, response_len);
 797
 798	/*
 799	 * XXX Abort if the response length is less than 36? If less than
 800	 * 32, the lookup of the device flags (above) could be invalid,
 801	 * and it would be possible to take an incorrect action - we do
 802	 * not want to hang because of a short INQUIRY. On the flip side,
 803	 * if the device is spun down or becoming ready (and so it gives a
 804	 * short INQUIRY), an abort here prevents any further use of the
 805	 * device, including spin up.
 806	 *
 807	 * On the whole, the best approach seems to be to assume the first
 808	 * 36 bytes are valid no matter what the device says.  That's
 809	 * better than copying < 36 bytes to the inquiry-result buffer
 810	 * and displaying garbage for the Vendor, Product, or Revision
 811	 * strings.
 812	 */
 813	if (sdev->inquiry_len < 36) {
 814		if (!sdev->host->short_inquiry) {
 815			shost_printk(KERN_INFO, sdev->host,
 816				    "scsi scan: INQUIRY result too short (%d),"
 817				    " using 36\n", sdev->inquiry_len);
 818			sdev->host->short_inquiry = 1;
 819		}
 820		sdev->inquiry_len = 36;
 821	}
 822
 823	/*
 824	 * Related to the above issue:
 825	 *
 826	 * XXX Devices (disk or all?) should be sent a TEST UNIT READY,
 827	 * and if not ready, sent a START_STOP to start (maybe spin up) and
 828	 * then send the INQUIRY again, since the INQUIRY can change after
 829	 * a device is initialized.
 830	 *
 831	 * Ideally, start a device if explicitly asked to do so.  This
 832	 * assumes that a device is spun up on power on, spun down on
 833	 * request, and then spun up on request.
 834	 */
 835
 836	/*
 837	 * The scanning code needs to know the scsi_level, even if no
 838	 * device is attached at LUN 0 (SCSI_SCAN_TARGET_PRESENT) so
 839	 * non-zero LUNs can be scanned.
 840	 */
 841	sdev->scsi_level = inq_result[2] & 0x0f;
 842	if (sdev->scsi_level >= 2 ||
 843	    (sdev->scsi_level == 1 && (inq_result[3] & 0x0f) == 1))
 844		sdev->scsi_level++;
 845	sdev->sdev_target->scsi_level = sdev->scsi_level;
 846
 847	/*
 848	 * If SCSI-2 or lower, and if the transport requires it,
 849	 * store the LUN value in CDB[1].
 850	 */
 851	sdev->lun_in_cdb = 0;
 852	if (sdev->scsi_level <= SCSI_2 &&
 853	    sdev->scsi_level != SCSI_UNKNOWN &&
 854	    !sdev->host->no_scsi2_lun_in_cdb)
 855		sdev->lun_in_cdb = 1;
 856
 857	return 0;
 858}
 859
 860/**
 861 * scsi_add_lun - allocate and fully initialze a scsi_device
 862 * @sdev:	holds information to be stored in the new scsi_device
 863 * @inq_result:	holds the result of a previous INQUIRY to the LUN
 864 * @bflags:	black/white list flag
 865 * @async:	1 if this device is being scanned asynchronously
 866 *
 867 * Description:
 868 *     Initialize the scsi_device @sdev.  Optionally set fields based
 869 *     on values in *@bflags.
 870 *
 871 * Return:
 872 *     SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
 873 *     SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
 874 **/
 875static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 876		blist_flags_t *bflags, int async)
 877{
 878	const struct scsi_host_template *hostt = sdev->host->hostt;
 879	struct queue_limits lim;
 880	int ret;
 881
 882	/*
 883	 * XXX do not save the inquiry, since it can change underneath us,
 884	 * save just vendor/model/rev.
 885	 *
 886	 * Rather than save it and have an ioctl that retrieves the saved
 887	 * value, have an ioctl that executes the same INQUIRY code used
 888	 * in scsi_probe_lun, let user level programs doing INQUIRY
 889	 * scanning run at their own risk, or supply a user level program
 890	 * that can correctly scan.
 891	 */
 892
 893	/*
 894	 * Copy at least 36 bytes of INQUIRY data, so that we don't
 895	 * dereference unallocated memory when accessing the Vendor,
 896	 * Product, and Revision strings.  Badly behaved devices may set
 897	 * the INQUIRY Additional Length byte to a small value, indicating
 898	 * these strings are invalid, but often they contain plausible data
 899	 * nonetheless.  It doesn't matter if the device sent < 36 bytes
 900	 * total, since scsi_probe_lun() initializes inq_result with 0s.
 901	 */
 902	sdev->inquiry = kmemdup(inq_result,
 903				max_t(size_t, sdev->inquiry_len, 36),
 904				GFP_KERNEL);
 905	if (sdev->inquiry == NULL)
 906		return SCSI_SCAN_NO_RESPONSE;
 907
 908	sdev->vendor = (char *) (sdev->inquiry + 8);
 909	sdev->model = (char *) (sdev->inquiry + 16);
 910	sdev->rev = (char *) (sdev->inquiry + 32);
 911
 912	sdev->is_ata = strncmp(sdev->vendor, "ATA     ", 8) == 0;
 913	if (sdev->is_ata) {
 914		/*
 915		 * sata emulation layer device.  This is a hack to work around
 916		 * the SATL power management specifications which state that
 917		 * when the SATL detects the device has gone into standby
 918		 * mode, it shall respond with NOT READY.
 919		 */
 920		sdev->allow_restart = 1;
 921	}
 922
 923	if (*bflags & BLIST_ISROM) {
 924		sdev->type = TYPE_ROM;
 925		sdev->removable = 1;
 926	} else {
 927		sdev->type = (inq_result[0] & 0x1f);
 928		sdev->removable = (inq_result[1] & 0x80) >> 7;
 929
 930		/*
 931		 * some devices may respond with wrong type for
 932		 * well-known logical units. Force well-known type
 933		 * to enumerate them correctly.
 934		 */
 935		if (scsi_is_wlun(sdev->lun) && sdev->type != TYPE_WLUN) {
 936			sdev_printk(KERN_WARNING, sdev,
 937				"%s: correcting incorrect peripheral device type 0x%x for W-LUN 0x%16xhN\n",
 938				__func__, sdev->type, (unsigned int)sdev->lun);
 939			sdev->type = TYPE_WLUN;
 940		}
 941
 942	}
 943
 944	if (sdev->type == TYPE_RBC || sdev->type == TYPE_ROM) {
 945		/* RBC and MMC devices can return SCSI-3 compliance and yet
 946		 * still not support REPORT LUNS, so make them act as
 947		 * BLIST_NOREPORTLUN unless BLIST_REPORTLUN2 is
 948		 * specifically set */
 949		if ((*bflags & BLIST_REPORTLUN2) == 0)
 950			*bflags |= BLIST_NOREPORTLUN;
 951	}
 952
 953	/*
 954	 * For a peripheral qualifier (PQ) value of 1 (001b), the SCSI
 955	 * spec says: The device server is capable of supporting the
 956	 * specified peripheral device type on this logical unit. However,
 957	 * the physical device is not currently connected to this logical
 958	 * unit.
 959	 *
 960	 * The above is vague, as it implies that we could treat 001 and
 961	 * 011 the same. Stay compatible with previous code, and create a
 962	 * scsi_device for a PQ of 1
 963	 *
 964	 * Don't set the device offline here; rather let the upper
 965	 * level drivers eval the PQ to decide whether they should
 966	 * attach. So remove ((inq_result[0] >> 5) & 7) == 1 check.
 967	 */ 
 968
 969	sdev->inq_periph_qual = (inq_result[0] >> 5) & 7;
 970	sdev->lockable = sdev->removable;
 971	sdev->soft_reset = (inq_result[7] & 1) && ((inq_result[3] & 7) == 2);
 972
 973	if (sdev->scsi_level >= SCSI_3 ||
 974			(sdev->inquiry_len > 56 && inq_result[56] & 0x04))
 975		sdev->ppr = 1;
 976	if (inq_result[7] & 0x60)
 977		sdev->wdtr = 1;
 978	if (inq_result[7] & 0x10)
 979		sdev->sdtr = 1;
 980
 981	sdev_printk(KERN_NOTICE, sdev, "%s %.8s %.16s %.4s PQ: %d "
 982			"ANSI: %d%s\n", scsi_device_type(sdev->type),
 983			sdev->vendor, sdev->model, sdev->rev,
 984			sdev->inq_periph_qual, inq_result[2] & 0x07,
 985			(inq_result[3] & 0x0f) == 1 ? " CCS" : "");
 986
 987	if ((sdev->scsi_level >= SCSI_2) && (inq_result[7] & 2) &&
 988	    !(*bflags & BLIST_NOTQ)) {
 989		sdev->tagged_supported = 1;
 990		sdev->simple_tags = 1;
 991	}
 992
 993	/*
 994	 * Some devices (Texel CD ROM drives) have handshaking problems
 995	 * when used with the Seagate controllers. borken is initialized
 996	 * to 1, and then set it to 0 here.
 997	 */
 998	if ((*bflags & BLIST_BORKEN) == 0)
 999		sdev->borken = 0;
1000
1001	if (*bflags & BLIST_NO_ULD_ATTACH)
1002		sdev->no_uld_attach = 1;
1003
1004	/*
1005	 * Apparently some really broken devices (contrary to the SCSI
1006	 * standards) need to be selected without asserting ATN
1007	 */
1008	if (*bflags & BLIST_SELECT_NO_ATN)
1009		sdev->select_no_atn = 1;
1010
1011	/*
1012	 * Some devices may not want to have a start command automatically
1013	 * issued when a device is added.
1014	 */
1015	if (*bflags & BLIST_NOSTARTONADD)
1016		sdev->no_start_on_add = 1;
1017
1018	if (*bflags & BLIST_SINGLELUN)
1019		scsi_target(sdev)->single_lun = 1;
1020
1021	sdev->use_10_for_rw = 1;
1022
1023	/* some devices don't like REPORT SUPPORTED OPERATION CODES
1024	 * and will simply timeout causing sd_mod init to take a very
1025	 * very long time */
1026	if (*bflags & BLIST_NO_RSOC)
1027		sdev->no_report_opcodes = 1;
1028
1029	/* set the device running here so that slave configure
1030	 * may do I/O */
1031	mutex_lock(&sdev->state_mutex);
1032	ret = scsi_device_set_state(sdev, SDEV_RUNNING);
1033	if (ret)
1034		ret = scsi_device_set_state(sdev, SDEV_BLOCK);
1035	mutex_unlock(&sdev->state_mutex);
1036
1037	if (ret) {
1038		sdev_printk(KERN_ERR, sdev,
1039			    "in wrong state %s to complete scan\n",
1040			    scsi_device_state_name(sdev->sdev_state));
1041		return SCSI_SCAN_NO_RESPONSE;
1042	}
1043
1044	if (*bflags & BLIST_NOT_LOCKABLE)
1045		sdev->lockable = 0;
1046
1047	if (*bflags & BLIST_RETRY_HWERROR)
1048		sdev->retry_hwerror = 1;
1049
1050	if (*bflags & BLIST_NO_DIF)
1051		sdev->no_dif = 1;
1052
1053	if (*bflags & BLIST_UNMAP_LIMIT_WS)
1054		sdev->unmap_limit_for_ws = 1;
1055
1056	if (*bflags & BLIST_IGN_MEDIA_CHANGE)
1057		sdev->ignore_media_change = 1;
1058
1059	sdev->eh_timeout = SCSI_DEFAULT_EH_TIMEOUT;
1060
1061	if (*bflags & BLIST_TRY_VPD_PAGES)
1062		sdev->try_vpd_pages = 1;
1063	else if (*bflags & BLIST_SKIP_VPD_PAGES)
1064		sdev->skip_vpd_pages = 1;
1065
1066	if (*bflags & BLIST_NO_VPD_SIZE)
1067		sdev->no_vpd_size = 1;
1068
1069	transport_configure_device(&sdev->sdev_gendev);
1070
1071	sdev->sdev_bflags = *bflags;
1072
1073	if (scsi_device_is_pseudo_dev(sdev))
1074		return SCSI_SCAN_LUN_PRESENT;
1075
1076	/*
1077	 * No need to freeze the queue as it isn't reachable to anyone else yet.
1078	 */
1079	lim = queue_limits_start_update(sdev->request_queue);
1080	if (*bflags & BLIST_MAX_512)
1081		lim.max_hw_sectors = 512;
1082	else if (*bflags & BLIST_MAX_1024)
1083		lim.max_hw_sectors = 1024;
1084
1085	if (hostt->sdev_configure)
1086		ret = hostt->sdev_configure(sdev, &lim);
1087	if (ret) {
1088		queue_limits_cancel_update(sdev->request_queue);
1089		/*
1090		 * If the LLDD reports device not present, don't clutter the
1091		 * console with failure messages.
1092		 */
1093		if (ret != -ENXIO)
1094			sdev_printk(KERN_ERR, sdev,
1095				"failed to configure device\n");
1096		return SCSI_SCAN_NO_RESPONSE;
1097	}
1098
1099	ret = queue_limits_commit_update(sdev->request_queue, &lim);
1100	if (ret) {
1101		sdev_printk(KERN_ERR, sdev, "failed to apply queue limits.\n");
1102		return SCSI_SCAN_NO_RESPONSE;
1103	}
1104
1105	/*
1106	 * The queue_depth is often changed in ->sdev_configure.
1107	 *
1108	 * Set up budget map again since memory consumption of the map depends
1109	 * on actual queue depth.
1110	 */
1111	if (hostt->sdev_configure)
1112		scsi_realloc_sdev_budget_map(sdev, sdev->queue_depth);
1113
1114	if (sdev->scsi_level >= SCSI_3)
1115		scsi_attach_vpd(sdev);
1116
1117	scsi_cdl_check(sdev);
1118
1119	sdev->max_queue_depth = sdev->queue_depth;
1120	WARN_ON_ONCE(sdev->max_queue_depth > sdev->budget_map.depth);
1121
1122	/*
1123	 * Ok, the device is now all set up, we can
1124	 * register it and tell the rest of the kernel
1125	 * about it.
1126	 */
1127	if (!async && scsi_sysfs_add_sdev(sdev) != 0)
1128		return SCSI_SCAN_NO_RESPONSE;
1129
1130	return SCSI_SCAN_LUN_PRESENT;
1131}
1132
1133#ifdef CONFIG_SCSI_LOGGING
1134/** 
1135 * scsi_inq_str - print INQUIRY data from min to max index, strip trailing whitespace
1136 * @buf:   Output buffer with at least end-first+1 bytes of space
1137 * @inq:   Inquiry buffer (input)
1138 * @first: Offset of string into inq
1139 * @end:   Index after last character in inq
1140 */
1141static unsigned char *scsi_inq_str(unsigned char *buf, unsigned char *inq,
1142				   unsigned first, unsigned end)
1143{
1144	unsigned term = 0, idx;
1145
1146	for (idx = 0; idx + first < end && idx + first < inq[4] + 5; idx++) {
1147		if (inq[idx+first] > ' ') {
1148			buf[idx] = inq[idx+first];
1149			term = idx+1;
1150		} else {
1151			buf[idx] = ' ';
1152		}
1153	}
1154	buf[term] = 0;
1155	return buf;
1156}
1157#endif
1158
1159/**
1160 * scsi_probe_and_add_lun - probe a LUN, if a LUN is found add it
1161 * @starget:	pointer to target device structure
1162 * @lun:	LUN of target device
1163 * @bflagsp:	store bflags here if not NULL
1164 * @sdevp:	probe the LUN corresponding to this scsi_device
1165 * @rescan:     if not equal to SCSI_SCAN_INITIAL skip some code only
1166 *              needed on first scan
1167 * @hostdata:	passed to scsi_alloc_sdev()
1168 *
1169 * Description:
1170 *     Call scsi_probe_lun, if a LUN with an attached device is found,
1171 *     allocate and set it up by calling scsi_add_lun.
1172 *
1173 * Return:
1174 *
1175 *   - SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
1176 *   - SCSI_SCAN_TARGET_PRESENT: target responded, but no device is
1177 *         attached at the LUN
1178 *   - SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
1179 **/
1180static int scsi_probe_and_add_lun(struct scsi_target *starget,
1181				  u64 lun, blist_flags_t *bflagsp,
1182				  struct scsi_device **sdevp,
1183				  enum scsi_scan_mode rescan,
1184				  void *hostdata)
1185{
1186	struct scsi_device *sdev;
1187	unsigned char *result;
1188	blist_flags_t bflags;
1189	int res = SCSI_SCAN_NO_RESPONSE, result_len = 256;
1190	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1191
1192	/*
1193	 * The rescan flag is used as an optimization, the first scan of a
1194	 * host adapter calls into here with rescan == 0.
1195	 */
1196	sdev = scsi_device_lookup_by_target(starget, lun);
1197	if (sdev) {
1198		if (rescan != SCSI_SCAN_INITIAL || !scsi_device_created(sdev)) {
1199			SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
1200				"scsi scan: device exists on %s\n",
1201				dev_name(&sdev->sdev_gendev)));
1202			if (sdevp)
1203				*sdevp = sdev;
1204			else
1205				scsi_device_put(sdev);
1206
1207			if (bflagsp)
1208				*bflagsp = scsi_get_device_flags(sdev,
1209								 sdev->vendor,
1210								 sdev->model);
1211			return SCSI_SCAN_LUN_PRESENT;
1212		}
1213		scsi_device_put(sdev);
1214	} else
1215		sdev = scsi_alloc_sdev(starget, lun, hostdata);
1216	if (!sdev)
1217		goto out;
1218
1219	if (scsi_device_is_pseudo_dev(sdev)) {
1220		if (bflagsp)
1221			*bflagsp = BLIST_NOLUN;
1222		return SCSI_SCAN_LUN_PRESENT;
1223	}
1224
1225	result = kmalloc(result_len, GFP_KERNEL);
1226	if (!result)
1227		goto out_free_sdev;
1228
1229	if (scsi_probe_lun(sdev, result, result_len, &bflags))
1230		goto out_free_result;
1231
1232	if (bflagsp)
1233		*bflagsp = bflags;
1234	/*
1235	 * result contains valid SCSI INQUIRY data.
1236	 */
1237	if ((result[0] >> 5) == 3) {
1238		/*
1239		 * For a Peripheral qualifier 3 (011b), the SCSI
1240		 * spec says: The device server is not capable of
1241		 * supporting a physical device on this logical
1242		 * unit.
1243		 *
1244		 * For disks, this implies that there is no
1245		 * logical disk configured at sdev->lun, but there
1246		 * is a target id responding.
1247		 */
1248		SCSI_LOG_SCAN_BUS(2, sdev_printk(KERN_INFO, sdev, "scsi scan:"
1249				   " peripheral qualifier of 3, device not"
1250				   " added\n"))
1251		if (lun == 0) {
1252			SCSI_LOG_SCAN_BUS(1, {
1253				unsigned char vend[9];
1254				unsigned char mod[17];
1255
1256				sdev_printk(KERN_INFO, sdev,
1257					"scsi scan: consider passing scsi_mod."
1258					"dev_flags=%s:%s:0x240 or 0x1000240\n",
1259					scsi_inq_str(vend, result, 8, 16),
1260					scsi_inq_str(mod, result, 16, 32));
1261			});
1262
1263		}
1264
1265		res = SCSI_SCAN_TARGET_PRESENT;
1266		goto out_free_result;
1267	}
1268
1269	/*
1270	 * Some targets may set slight variations of PQ and PDT to signal
1271	 * that no LUN is present, so don't add sdev in these cases.
1272	 * Two specific examples are:
1273	 * 1) NetApp targets: return PQ=1, PDT=0x1f
1274	 * 2) USB UFI: returns PDT=0x1f, with the PQ bits being "reserved"
1275	 *    in the UFI 1.0 spec (we cannot rely on reserved bits).
1276	 *
1277	 * References:
1278	 * 1) SCSI SPC-3, pp. 145-146
1279	 * PQ=1: "A peripheral device having the specified peripheral
1280	 * device type is not connected to this logical unit. However, the
1281	 * device server is capable of supporting the specified peripheral
1282	 * device type on this logical unit."
1283	 * PDT=0x1f: "Unknown or no device type"
1284	 * 2) USB UFI 1.0, p. 20
1285	 * PDT=00h Direct-access device (floppy)
1286	 * PDT=1Fh none (no FDD connected to the requested logical unit)
1287	 */
1288	if (((result[0] >> 5) == 1 || starget->pdt_1f_for_no_lun) &&
1289	    (result[0] & 0x1f) == 0x1f &&
1290	    !scsi_is_wlun(lun)) {
1291		SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
1292					"scsi scan: peripheral device type"
1293					" of 31, no device added\n"));
1294		res = SCSI_SCAN_TARGET_PRESENT;
1295		goto out_free_result;
1296	}
1297
1298	res = scsi_add_lun(sdev, result, &bflags, shost->async_scan);
1299	if (res == SCSI_SCAN_LUN_PRESENT) {
1300		if (bflags & BLIST_KEY) {
1301			sdev->lockable = 0;
1302			scsi_unlock_floptical(sdev, result);
1303		}
1304	}
1305
1306 out_free_result:
1307	kfree(result);
1308 out_free_sdev:
1309	if (res == SCSI_SCAN_LUN_PRESENT) {
1310		if (sdevp) {
1311			if (scsi_device_get(sdev) == 0) {
1312				*sdevp = sdev;
1313			} else {
1314				__scsi_remove_device(sdev);
1315				res = SCSI_SCAN_NO_RESPONSE;
1316			}
1317		}
1318	} else
1319		__scsi_remove_device(sdev);
1320 out:
1321	return res;
1322}
1323
1324/**
1325 * scsi_sequential_lun_scan - sequentially scan a SCSI target
1326 * @starget:	pointer to target structure to scan
1327 * @bflags:	black/white list flag for LUN 0
1328 * @scsi_level: Which version of the standard does this device adhere to
1329 * @rescan:     passed to scsi_probe_add_lun()
1330 *
1331 * Description:
1332 *     Generally, scan from LUN 1 (LUN 0 is assumed to already have been
1333 *     scanned) to some maximum lun until a LUN is found with no device
1334 *     attached. Use the bflags to figure out any oddities.
1335 *
1336 *     Modifies sdevscan->lun.
1337 **/
1338static void scsi_sequential_lun_scan(struct scsi_target *starget,
1339				     blist_flags_t bflags, int scsi_level,
1340				     enum scsi_scan_mode rescan)
1341{
1342	uint max_dev_lun;
1343	u64 sparse_lun, lun;
1344	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1345
1346	SCSI_LOG_SCAN_BUS(3, starget_printk(KERN_INFO, starget,
1347		"scsi scan: Sequential scan\n"));
1348
1349	max_dev_lun = min(max_scsi_luns, shost->max_lun);
1350	/*
1351	 * If this device is known to support sparse multiple units,
1352	 * override the other settings, and scan all of them. Normally,
1353	 * SCSI-3 devices should be scanned via the REPORT LUNS.
1354	 */
1355	if (bflags & BLIST_SPARSELUN) {
1356		max_dev_lun = shost->max_lun;
1357		sparse_lun = 1;
1358	} else
1359		sparse_lun = 0;
1360
1361	/*
1362	 * If less than SCSI_1_CCS, and no special lun scanning, stop
1363	 * scanning; this matches 2.4 behaviour, but could just be a bug
1364	 * (to continue scanning a SCSI_1_CCS device).
1365	 *
1366	 * This test is broken.  We might not have any device on lun0 for
1367	 * a sparselun device, and if that's the case then how would we
1368	 * know the real scsi_level, eh?  It might make sense to just not
1369	 * scan any SCSI_1 device for non-0 luns, but that check would best
1370	 * go into scsi_alloc_sdev() and just have it return null when asked
1371	 * to alloc an sdev for lun > 0 on an already found SCSI_1 device.
1372	 *
1373	if ((sdevscan->scsi_level < SCSI_1_CCS) &&
1374	    ((bflags & (BLIST_FORCELUN | BLIST_SPARSELUN | BLIST_MAX5LUN))
1375	     == 0))
1376		return;
1377	 */
1378	/*
1379	 * If this device is known to support multiple units, override
1380	 * the other settings, and scan all of them.
1381	 */
1382	if (bflags & BLIST_FORCELUN)
1383		max_dev_lun = shost->max_lun;
1384	/*
1385	 * REGAL CDC-4X: avoid hang after LUN 4
1386	 */
1387	if (bflags & BLIST_MAX5LUN)
1388		max_dev_lun = min(5U, max_dev_lun);
1389	/*
1390	 * Do not scan SCSI-2 or lower device past LUN 7, unless
1391	 * BLIST_LARGELUN.
1392	 */
1393	if (scsi_level < SCSI_3 && !(bflags & BLIST_LARGELUN))
1394		max_dev_lun = min(8U, max_dev_lun);
1395	else
1396		max_dev_lun = min(256U, max_dev_lun);
1397
1398	/*
1399	 * We have already scanned LUN 0, so start at LUN 1. Keep scanning
1400	 * until we reach the max, or no LUN is found and we are not
1401	 * sparse_lun.
1402	 */
1403	for (lun = 1; lun < max_dev_lun; ++lun)
1404		if ((scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan,
1405					    NULL) != SCSI_SCAN_LUN_PRESENT) &&
1406		    !sparse_lun)
1407			return;
1408}
1409
1410/**
1411 * scsi_report_lun_scan - Scan using SCSI REPORT LUN results
1412 * @starget: which target
1413 * @bflags: Zero or a mix of BLIST_NOLUN, BLIST_REPORTLUN2, or BLIST_NOREPORTLUN
1414 * @rescan: nonzero if we can skip code only needed on first scan
1415 *
1416 * Description:
1417 *   Fast scanning for modern (SCSI-3) devices by sending a REPORT LUN command.
1418 *   Scan the resulting list of LUNs by calling scsi_probe_and_add_lun.
1419 *
1420 *   If BLINK_REPORTLUN2 is set, scan a target that supports more than 8
1421 *   LUNs even if it's older than SCSI-3.
1422 *   If BLIST_NOREPORTLUN is set, return 1 always.
1423 *   If BLIST_NOLUN is set, return 0 always.
1424 *   If starget->no_report_luns is set, return 1 always.
1425 *
1426 * Return:
1427 *     0: scan completed (or no memory, so further scanning is futile)
1428 *     1: could not scan with REPORT LUN
1429 **/
1430static int scsi_report_lun_scan(struct scsi_target *starget, blist_flags_t bflags,
1431				enum scsi_scan_mode rescan)
1432{
1433	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
1434	unsigned int length;
1435	u64 lun;
1436	unsigned int num_luns;
1437	int result;
1438	struct scsi_lun *lunp, *lun_data;
1439	struct scsi_device *sdev;
1440	struct Scsi_Host *shost = dev_to_shost(&starget->dev);
1441	struct scsi_failure failure_defs[] = {
1442		{
1443			.sense = UNIT_ATTENTION,
1444			.asc = SCMD_FAILURE_ASC_ANY,
1445			.ascq = SCMD_FAILURE_ASCQ_ANY,
1446			.result = SAM_STAT_CHECK_CONDITION,
1447		},
1448		/* Fail all CCs except the UA above */
1449		{
1450			.sense = SCMD_FAILURE_SENSE_ANY,
1451			.result = SAM_STAT_CHECK_CONDITION,
1452		},
1453		/* Retry any other errors not listed above */
1454		{
1455			.result = SCMD_FAILURE_RESULT_ANY,
1456		},
1457		{}
1458	};
1459	struct scsi_failures failures = {
1460		.total_allowed = 3,
1461		.failure_definitions = failure_defs,
1462	};
1463	const struct scsi_exec_args exec_args = {
1464		.failures = &failures,
1465	};
1466	int ret = 0;
1467
1468	/*
1469	 * Only support SCSI-3 and up devices if BLIST_NOREPORTLUN is not set.
1470	 * Also allow SCSI-2 if BLIST_REPORTLUN2 is set and host adapter does
1471	 * support more than 8 LUNs.
1472	 * Don't attempt if the target doesn't support REPORT LUNS.
1473	 */
1474	if (bflags & BLIST_NOREPORTLUN)
1475		return 1;
1476	if (starget->scsi_level < SCSI_2 &&
1477	    starget->scsi_level != SCSI_UNKNOWN)
1478		return 1;
1479	if (starget->scsi_level < SCSI_3 &&
1480	    (!(bflags & BLIST_REPORTLUN2) || shost->max_lun <= 8))
1481		return 1;
1482	if (bflags & BLIST_NOLUN)
1483		return 0;
1484	if (starget->no_report_luns)
1485		return 1;
1486
1487	if (!(sdev = scsi_device_lookup_by_target(starget, 0))) {
1488		sdev = scsi_alloc_sdev(starget, 0, NULL);
1489		if (!sdev)
1490			return 0;
1491		if (scsi_device_get(sdev)) {
1492			__scsi_remove_device(sdev);
1493			return 0;
1494		}
1495	}
1496
1497	/*
1498	 * Allocate enough to hold the header (the same size as one scsi_lun)
1499	 * plus the number of luns we are requesting.  511 was the default
1500	 * value of the now removed max_report_luns parameter.
1501	 */
1502	length = (511 + 1) * sizeof(struct scsi_lun);
1503retry:
1504	lun_data = kmalloc(length, GFP_KERNEL);
1505	if (!lun_data) {
1506		printk(ALLOC_FAILURE_MSG, __func__);
1507		goto out;
1508	}
1509
1510	scsi_cmd[0] = REPORT_LUNS;
1511
1512	/*
1513	 * bytes 1 - 5: reserved, set to zero.
1514	 */
1515	memset(&scsi_cmd[1], 0, 5);
1516
1517	/*
1518	 * bytes 6 - 9: length of the command.
1519	 */
1520	put_unaligned_be32(length, &scsi_cmd[6]);
1521
1522	scsi_cmd[10] = 0;	/* reserved */
1523	scsi_cmd[11] = 0;	/* control */
1524
1525	/*
1526	 * We can get a UNIT ATTENTION, for example a power on/reset, so
1527	 * retry a few times (like sd.c does for TEST UNIT READY).
1528	 * Experience shows some combinations of adapter/devices get at
1529	 * least two power on/resets.
1530	 *
1531	 * Illegal requests (for devices that do not support REPORT LUNS)
1532	 * should come through as a check condition, and will not generate
1533	 * a retry.
1534	 */
1535	scsi_failures_reset_retries(&failures);
1536
1537	SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1538			  "scsi scan: Sending REPORT LUNS\n"));
1539
1540	result = scsi_execute_cmd(sdev, scsi_cmd, REQ_OP_DRV_IN, lun_data,
1541				  length, SCSI_REPORT_LUNS_TIMEOUT, 3,
1542				  &exec_args);
1543
1544	SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1545			  "scsi scan: REPORT LUNS  %s result 0x%x\n",
1546			  result ?  "failed" : "successful", result));
1547	if (result) {
1548		/*
1549		 * The device probably does not support a REPORT LUN command
1550		 */
1551		ret = 1;
1552		goto out_err;
1553	}
1554
1555	/*
1556	 * Get the length from the first four bytes of lun_data.
1557	 */
1558	if (get_unaligned_be32(lun_data->scsi_lun) +
1559	    sizeof(struct scsi_lun) > length) {
1560		length = get_unaligned_be32(lun_data->scsi_lun) +
1561			 sizeof(struct scsi_lun);
1562		kfree(lun_data);
1563		goto retry;
1564	}
1565	length = get_unaligned_be32(lun_data->scsi_lun);
1566
1567	num_luns = (length / sizeof(struct scsi_lun));
1568
1569	SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
1570		"scsi scan: REPORT LUN scan\n"));
1571
1572	/*
1573	 * Scan the luns in lun_data. The entry at offset 0 is really
1574	 * the header, so start at 1 and go up to and including num_luns.
1575	 */
1576	for (lunp = &lun_data[1]; lunp <= &lun_data[num_luns]; lunp++) {
1577		lun = scsilun_to_int(lunp);
1578
1579		if (lun > sdev->host->max_lun) {
1580			sdev_printk(KERN_WARNING, sdev,
1581				    "lun%llu has a LUN larger than"
1582				    " allowed by the host adapter\n", lun);
1583		} else {
1584			int res;
1585
1586			res = scsi_probe_and_add_lun(starget,
1587				lun, NULL, NULL, rescan, NULL);
1588			if (res == SCSI_SCAN_NO_RESPONSE) {
1589				/*
1590				 * Got some results, but now none, abort.
1591				 */
1592				sdev_printk(KERN_ERR, sdev,
1593					"Unexpected response"
1594					" from lun %llu while scanning, scan"
1595					" aborted\n", (unsigned long long)lun);
1596				break;
1597			}
1598		}
1599	}
1600
1601 out_err:
1602	kfree(lun_data);
1603 out:
1604	if (scsi_device_created(sdev))
1605		/*
1606		 * the sdev we used didn't appear in the report luns scan
1607		 */
1608		__scsi_remove_device(sdev);
1609	scsi_device_put(sdev);
1610	return ret;
1611}
1612
1613struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
1614				      uint id, u64 lun, void *hostdata)
1615{
1616	struct scsi_device *sdev = ERR_PTR(-ENODEV);
1617	struct device *parent = &shost->shost_gendev;
1618	struct scsi_target *starget;
1619
1620	if (strncmp(scsi_scan_type, "none", 4) == 0)
1621		return ERR_PTR(-ENODEV);
1622
1623	starget = scsi_alloc_target(parent, channel, id);
1624	if (!starget)
1625		return ERR_PTR(-ENOMEM);
1626	scsi_autopm_get_target(starget);
1627
1628	mutex_lock(&shost->scan_mutex);
1629	if (!shost->async_scan)
1630		scsi_complete_async_scans();
1631
1632	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1633		scsi_probe_and_add_lun(starget, lun, NULL, &sdev,
1634				       SCSI_SCAN_RESCAN, hostdata);
1635		scsi_autopm_put_host(shost);
1636	}
1637	mutex_unlock(&shost->scan_mutex);
1638	scsi_autopm_put_target(starget);
1639	/*
1640	 * paired with scsi_alloc_target().  Target will be destroyed unless
1641	 * scsi_probe_and_add_lun made an underlying device visible
1642	 */
1643	scsi_target_reap(starget);
1644	put_device(&starget->dev);
1645
1646	return sdev;
1647}
1648EXPORT_SYMBOL(__scsi_add_device);
1649
1650/**
1651 * scsi_add_device - creates a new SCSI (LU) instance
1652 * @host: the &Scsi_Host instance where the device is located
1653 * @channel: target channel number (rarely other than %0)
1654 * @target: target id number
1655 * @lun: LUN of target device
1656 *
1657 * Probe for a specific LUN and add it if found.
1658 *
1659 * Notes: This call is usually performed internally during a SCSI
1660 * bus scan when an HBA is added (i.e. scsi_scan_host()). So it
1661 * should only be called if the HBA becomes aware of a new SCSI
1662 * device (LU) after scsi_scan_host() has completed. If successful
1663 * this call can lead to sdev_init() and sdev_configure() callbacks
1664 * into the LLD.
1665 *
1666 * Return: %0 on success or negative error code on failure
1667 */
1668int scsi_add_device(struct Scsi_Host *host, uint channel,
1669		    uint target, u64 lun)
1670{
1671	struct scsi_device *sdev = 
1672		__scsi_add_device(host, channel, target, lun, NULL);
1673	if (IS_ERR(sdev))
1674		return PTR_ERR(sdev);
1675
1676	scsi_device_put(sdev);
1677	return 0;
1678}
1679EXPORT_SYMBOL(scsi_add_device);
1680
1681int scsi_resume_device(struct scsi_device *sdev)
1682{
1683	struct device *dev = &sdev->sdev_gendev;
1684	int ret = 0;
1685
1686	device_lock(dev);
1687
1688	/*
1689	 * Bail out if the device or its queue are not running. Otherwise,
1690	 * the rescan may block waiting for commands to be executed, with us
1691	 * holding the device lock. This can result in a potential deadlock
1692	 * in the power management core code when system resume is on-going.
1693	 */
1694	if (sdev->sdev_state != SDEV_RUNNING ||
1695	    blk_queue_pm_only(sdev->request_queue)) {
1696		ret = -EWOULDBLOCK;
1697		goto unlock;
1698	}
1699
1700	if (dev->driver && try_module_get(dev->driver->owner)) {
1701		struct scsi_driver *drv = to_scsi_driver(dev->driver);
1702
1703		if (drv->resume)
1704			ret = drv->resume(dev);
1705		module_put(dev->driver->owner);
1706	}
1707
1708unlock:
1709	device_unlock(dev);
1710
1711	return ret;
1712}
1713EXPORT_SYMBOL(scsi_resume_device);
1714
1715int scsi_rescan_device(struct scsi_device *sdev)
1716{
1717	struct device *dev = &sdev->sdev_gendev;
1718	int ret = 0;
1719
1720	device_lock(dev);
1721
1722	/*
1723	 * Bail out if the device or its queue are not running. Otherwise,
1724	 * the rescan may block waiting for commands to be executed, with us
1725	 * holding the device lock. This can result in a potential deadlock
1726	 * in the power management core code when system resume is on-going.
1727	 */
1728	if (sdev->sdev_state != SDEV_RUNNING ||
1729	    blk_queue_pm_only(sdev->request_queue)) {
1730		ret = -EWOULDBLOCK;
1731		goto unlock;
1732	}
1733
1734	scsi_attach_vpd(sdev);
1735	scsi_cdl_check(sdev);
1736
1737	if (sdev->handler && sdev->handler->rescan)
1738		sdev->handler->rescan(sdev);
1739
1740	if (dev->driver && try_module_get(dev->driver->owner)) {
1741		struct scsi_driver *drv = to_scsi_driver(dev->driver);
1742
1743		if (drv->rescan)
1744			drv->rescan(dev);
1745		module_put(dev->driver->owner);
1746	}
1747
1748unlock:
1749	device_unlock(dev);
1750
1751	return ret;
1752}
1753EXPORT_SYMBOL(scsi_rescan_device);
1754
1755static void __scsi_scan_target(struct device *parent, unsigned int channel,
1756		unsigned int id, u64 lun, enum scsi_scan_mode rescan)
1757{
1758	struct Scsi_Host *shost = dev_to_shost(parent);
1759	blist_flags_t bflags = 0;
1760	int res;
1761	struct scsi_target *starget;
1762
1763	if (shost->this_id == id)
1764		/*
1765		 * Don't scan the host adapter
1766		 */
1767		return;
1768
1769	starget = scsi_alloc_target(parent, channel, id);
1770	if (!starget)
1771		return;
1772	scsi_autopm_get_target(starget);
1773
1774	if (lun != SCAN_WILD_CARD) {
1775		/*
1776		 * Scan for a specific host/chan/id/lun.
1777		 */
1778		scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan, NULL);
1779		goto out_reap;
1780	}
1781
1782	/*
1783	 * Scan LUN 0, if there is some response, scan further. Ideally, we
1784	 * would not configure LUN 0 until all LUNs are scanned.
1785	 */
1786	res = scsi_probe_and_add_lun(starget, 0, &bflags, NULL, rescan, NULL);
1787	if (res == SCSI_SCAN_LUN_PRESENT || res == SCSI_SCAN_TARGET_PRESENT) {
1788		if (scsi_report_lun_scan(starget, bflags, rescan) != 0)
1789			/*
1790			 * The REPORT LUN did not scan the target,
1791			 * do a sequential scan.
1792			 */
1793			scsi_sequential_lun_scan(starget, bflags,
1794						 starget->scsi_level, rescan);
1795	}
1796
1797 out_reap:
1798	scsi_autopm_put_target(starget);
1799	/*
1800	 * paired with scsi_alloc_target(): determine if the target has
1801	 * any children at all and if not, nuke it
1802	 */
1803	scsi_target_reap(starget);
1804
1805	put_device(&starget->dev);
1806}
1807
1808/**
1809 * scsi_scan_target - scan a target id, possibly including all LUNs on the target.
1810 * @parent:	host to scan
1811 * @channel:	channel to scan
1812 * @id:		target id to scan
1813 * @lun:	Specific LUN to scan or SCAN_WILD_CARD
1814 * @rescan:	passed to LUN scanning routines; SCSI_SCAN_INITIAL for
1815 *              no rescan, SCSI_SCAN_RESCAN to rescan existing LUNs,
1816 *              and SCSI_SCAN_MANUAL to force scanning even if
1817 *              'scan=manual' is set.
1818 *
1819 * Description:
1820 *     Scan the target id on @parent, @channel, and @id. Scan at least LUN 0,
1821 *     and possibly all LUNs on the target id.
1822 *
1823 *     First try a REPORT LUN scan, if that does not scan the target, do a
1824 *     sequential scan of LUNs on the target id.
1825 **/
1826void scsi_scan_target(struct device *parent, unsigned int channel,
1827		      unsigned int id, u64 lun, enum scsi_scan_mode rescan)
1828{
1829	struct Scsi_Host *shost = dev_to_shost(parent);
1830
1831	if (strncmp(scsi_scan_type, "none", 4) == 0)
1832		return;
1833
1834	if (rescan != SCSI_SCAN_MANUAL &&
1835	    strncmp(scsi_scan_type, "manual", 6) == 0)
1836		return;
1837
1838	mutex_lock(&shost->scan_mutex);
1839	if (!shost->async_scan)
1840		scsi_complete_async_scans();
1841
1842	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1843		__scsi_scan_target(parent, channel, id, lun, rescan);
1844		scsi_autopm_put_host(shost);
1845	}
1846	mutex_unlock(&shost->scan_mutex);
1847}
1848EXPORT_SYMBOL(scsi_scan_target);
1849
1850static void scsi_scan_channel(struct Scsi_Host *shost, unsigned int channel,
1851			      unsigned int id, u64 lun,
1852			      enum scsi_scan_mode rescan)
1853{
1854	uint order_id;
1855
1856	if (id == SCAN_WILD_CARD)
1857		for (id = 0; id < shost->max_id; ++id) {
1858			/*
1859			 * XXX adapter drivers when possible (FCP, iSCSI)
1860			 * could modify max_id to match the current max,
1861			 * not the absolute max.
1862			 *
1863			 * XXX add a shost id iterator, so for example,
1864			 * the FC ID can be the same as a target id
1865			 * without a huge overhead of sparse id's.
1866			 */
1867			if (shost->reverse_ordering)
1868				/*
1869				 * Scan from high to low id.
1870				 */
1871				order_id = shost->max_id - id - 1;
1872			else
1873				order_id = id;
1874			__scsi_scan_target(&shost->shost_gendev, channel,
1875					order_id, lun, rescan);
1876		}
1877	else
1878		__scsi_scan_target(&shost->shost_gendev, channel,
1879				id, lun, rescan);
1880}
1881
1882int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel,
1883			    unsigned int id, u64 lun,
1884			    enum scsi_scan_mode rescan)
1885{
1886	SCSI_LOG_SCAN_BUS(3, shost_printk (KERN_INFO, shost,
1887		"%s: <%u:%u:%llu>\n",
1888		__func__, channel, id, lun));
1889
1890	if (((channel != SCAN_WILD_CARD) && (channel > shost->max_channel)) ||
1891	    ((id != SCAN_WILD_CARD) && (id >= shost->max_id)) ||
1892	    ((lun != SCAN_WILD_CARD) && (lun >= shost->max_lun)))
1893		return -EINVAL;
1894
1895	mutex_lock(&shost->scan_mutex);
1896	if (!shost->async_scan)
1897		scsi_complete_async_scans();
1898
1899	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
1900		if (channel == SCAN_WILD_CARD)
1901			for (channel = 0; channel <= shost->max_channel;
1902			     channel++)
1903				scsi_scan_channel(shost, channel, id, lun,
1904						  rescan);
1905		else
1906			scsi_scan_channel(shost, channel, id, lun, rescan);
1907		scsi_autopm_put_host(shost);
1908	}
1909	mutex_unlock(&shost->scan_mutex);
1910
1911	return 0;
1912}
1913EXPORT_SYMBOL(scsi_scan_host_selected);
1914static void scsi_sysfs_add_devices(struct Scsi_Host *shost)
1915{
1916	struct scsi_device *sdev;
1917	shost_for_each_device(sdev, shost) {
1918		/* target removed before the device could be added */
1919		if (sdev->sdev_state == SDEV_DEL)
1920			continue;
1921		/* If device is already visible, skip adding it to sysfs */
1922		if (sdev->is_visible)
1923			continue;
1924		if (!scsi_host_scan_allowed(shost) ||
1925		    scsi_sysfs_add_sdev(sdev) != 0)
1926			__scsi_remove_device(sdev);
1927	}
1928}
1929
1930/**
1931 * scsi_prep_async_scan - prepare for an async scan
1932 * @shost: the host which will be scanned
1933 * Returns: a cookie to be passed to scsi_finish_async_scan()
1934 *
1935 * Tells the midlayer this host is going to do an asynchronous scan.
1936 * It reserves the host's position in the scanning list and ensures
1937 * that other asynchronous scans started after this one won't affect the
1938 * ordering of the discovered devices.
1939 */
1940static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost)
1941{
1942	struct async_scan_data *data = NULL;
1943	unsigned long flags;
1944
1945	if (strncmp(scsi_scan_type, "sync", 4) == 0)
1946		return NULL;
1947
1948	mutex_lock(&shost->scan_mutex);
1949	if (shost->async_scan) {
1950		shost_printk(KERN_DEBUG, shost, "%s called twice\n", __func__);
1951		goto err;
1952	}
1953
1954	data = kmalloc(sizeof(*data), GFP_KERNEL);
1955	if (!data)
1956		goto err;
1957	data->shost = scsi_host_get(shost);
1958	if (!data->shost)
1959		goto err;
1960	init_completion(&data->prev_finished);
1961
1962	spin_lock_irqsave(shost->host_lock, flags);
1963	shost->async_scan = 1;
1964	spin_unlock_irqrestore(shost->host_lock, flags);
1965	mutex_unlock(&shost->scan_mutex);
1966
1967	spin_lock(&async_scan_lock);
1968	if (list_empty(&scanning_hosts))
1969		complete(&data->prev_finished);
1970	list_add_tail(&data->list, &scanning_hosts);
1971	spin_unlock(&async_scan_lock);
1972
1973	return data;
1974
1975 err:
1976	mutex_unlock(&shost->scan_mutex);
1977	kfree(data);
1978	return NULL;
1979}
1980
1981/**
1982 * scsi_finish_async_scan - asynchronous scan has finished
1983 * @data: cookie returned from earlier call to scsi_prep_async_scan()
1984 *
1985 * All the devices currently attached to this host have been found.
1986 * This function announces all the devices it has found to the rest
1987 * of the system.
1988 */
1989static void scsi_finish_async_scan(struct async_scan_data *data)
1990{
1991	struct Scsi_Host *shost;
1992	unsigned long flags;
1993
1994	if (!data)
1995		return;
1996
1997	shost = data->shost;
1998
1999	mutex_lock(&shost->scan_mutex);
2000
2001	if (!shost->async_scan) {
2002		shost_printk(KERN_INFO, shost, "%s called twice\n", __func__);
2003		dump_stack();
2004		mutex_unlock(&shost->scan_mutex);
2005		return;
2006	}
2007
2008	wait_for_completion(&data->prev_finished);
2009
2010	scsi_sysfs_add_devices(shost);
2011
2012	spin_lock_irqsave(shost->host_lock, flags);
2013	shost->async_scan = 0;
2014	spin_unlock_irqrestore(shost->host_lock, flags);
2015
2016	mutex_unlock(&shost->scan_mutex);
2017
2018	spin_lock(&async_scan_lock);
2019	list_del(&data->list);
2020	if (!list_empty(&scanning_hosts)) {
2021		struct async_scan_data *next = list_entry(scanning_hosts.next,
2022				struct async_scan_data, list);
2023		complete(&next->prev_finished);
2024	}
2025	spin_unlock(&async_scan_lock);
2026
2027	scsi_autopm_put_host(shost);
2028	scsi_host_put(shost);
2029	kfree(data);
2030}
2031
2032static void do_scsi_scan_host(struct Scsi_Host *shost)
2033{
2034	if (shost->hostt->scan_finished) {
2035		unsigned long start = jiffies;
2036		if (shost->hostt->scan_start)
2037			shost->hostt->scan_start(shost);
2038
2039		while (!shost->hostt->scan_finished(shost, jiffies - start))
2040			msleep(10);
2041	} else {
2042		scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD,
2043				SCAN_WILD_CARD, SCSI_SCAN_INITIAL);
2044	}
2045}
2046
2047static void do_scan_async(void *_data, async_cookie_t c)
2048{
2049	struct async_scan_data *data = _data;
2050	struct Scsi_Host *shost = data->shost;
2051
2052	do_scsi_scan_host(shost);
2053	scsi_finish_async_scan(data);
2054}
2055
2056/**
2057 * scsi_scan_host - scan the given adapter
2058 * @shost:	adapter to scan
2059 *
2060 * Notes: Should be called after scsi_add_host()
2061 **/
2062void scsi_scan_host(struct Scsi_Host *shost)
2063{
2064	struct async_scan_data *data;
2065
2066	if (strncmp(scsi_scan_type, "none", 4) == 0 ||
2067	    strncmp(scsi_scan_type, "manual", 6) == 0)
2068		return;
2069	if (scsi_autopm_get_host(shost) < 0)
2070		return;
2071
2072	data = scsi_prep_async_scan(shost);
2073	if (!data) {
2074		do_scsi_scan_host(shost);
2075		scsi_autopm_put_host(shost);
2076		return;
2077	}
2078
2079	/* register with the async subsystem so wait_for_device_probe()
2080	 * will flush this work
2081	 */
2082	async_schedule(do_scan_async, data);
2083
2084	/* scsi_autopm_put_host(shost) is called in scsi_finish_async_scan() */
2085}
2086EXPORT_SYMBOL(scsi_scan_host);
2087
2088void scsi_forget_host(struct Scsi_Host *shost)
2089{
2090	struct scsi_device *sdev;
2091	unsigned long flags;
2092
2093 restart:
2094	spin_lock_irqsave(shost->host_lock, flags);
2095	list_for_each_entry(sdev, &shost->__devices, siblings) {
2096		if (scsi_device_is_pseudo_dev(sdev) ||
2097		    sdev->sdev_state == SDEV_DEL)
2098			continue;
2099		spin_unlock_irqrestore(shost->host_lock, flags);
2100		__scsi_remove_device(sdev);
2101		goto restart;
2102	}
2103	spin_unlock_irqrestore(shost->host_lock, flags);
2104
2105	/*
2106	 * Remove the pseudo device last since it may be needed during removal
2107	 * of other SCSI devices.
2108	 */
2109	if (shost->pseudo_sdev)
2110		__scsi_remove_device(shost->pseudo_sdev);
2111}
2112
2113/**
2114 * scsi_get_pseudo_sdev() - Attach a pseudo SCSI device to a SCSI host
2115 * @shost: Host that needs a pseudo SCSI device
2116 *
2117 * Lock status: None assumed.
2118 *
2119 * Returns:     The scsi_device or NULL
2120 *
2121 * Notes:
2122 *	Attach a single scsi_device to the Scsi_Host. The primary aim for this
2123 *	device is to serve as a container from which SCSI commands can be
2124 *	allocated. Each SCSI command will carry a command tag allocated by the
2125 *	block layer. These SCSI commands can be used by the LLDD to send
2126 *	internal or passthrough commands without having to manage tag allocation
2127 *	inside the LLDD.
2128 */
2129struct scsi_device *scsi_get_pseudo_sdev(struct Scsi_Host *shost)
2130{
2131	struct scsi_device *sdev = NULL;
2132	struct scsi_target *starget;
2133
2134	guard(mutex)(&shost->scan_mutex);
2135
2136	if (!scsi_host_scan_allowed(shost))
2137		goto out;
2138
2139	starget = scsi_alloc_target(&shost->shost_gendev, 0, shost->max_id);
2140	if (!starget)
2141		goto out;
2142
2143	sdev = scsi_alloc_sdev(starget, U64_MAX, NULL);
2144	if (!sdev) {
2145		scsi_target_reap(starget);
2146		goto put_target;
2147	}
2148
2149	sdev->borken = 0;
2150
2151put_target:
2152	/* See also the get_device(dev) call in scsi_alloc_target(). */
2153	put_device(&starget->dev);
2154
2155out:
2156	return sdev;
2157}