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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * scsi_scan.c
  *
  * Copyright (C) 2000 Eric Youngdale,
  * Copyright (C) 2002 Patrick Mansfield
  *
  * The general scanning/probing algorithm is as follows, exceptions are
  * made to it depending on device specific flags, compilation options, and
  * global variable (boot or module load time) settings.
  *
  * A specific LUN is scanned via an INQUIRY command; if the LUN has a
  * device attached, a scsi_device is allocated and setup for it.
  *
  * For every id of every channel on the given host:
  *
  *  Scan LUN 0; if the target responds to LUN 0 (even if there is no
  *  device or storage attached to LUN 0):
  *
  *      If LUN 0 has a device attached, allocate and setup a
  *      scsi_device for it.
  *
  *      If target is SCSI-3 or up, issue a REPORT LUN, and scan
  *      all of the LUNs returned by the REPORT LUN; else,
  *      sequentially scan LUNs up until some maximum is reached,
  *      or a LUN is seen that cannot have a device attached to it.
  */
 
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/init.h>
 #include <linux/blkdev.h>
 #include <linux/delay.h>
 #include <linux/kthread.h>
 #include <linux/spinlock.h>
 #include <linux/async.h>
 #include <linux/slab.h>
 #include <asm/unaligned.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_cmnd.h>
 #include <scsi/scsi_device.h>
 #include <scsi/scsi_driver.h>
 #include <scsi/scsi_devinfo.h>
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_transport.h>
 #include <scsi/scsi_dh.h>
 #include <scsi/scsi_eh.h>
 
 #include "scsi_priv.h"
 #include "scsi_logging.h"
 
 #define ALLOC_FAILURE_MSG   KERN_ERR "%s: Allocation failure during" \
     " SCSI scanning, some SCSI devices might not be configured\n"
 
 /*
  * Default timeout
  */
 #define SCSI_TIMEOUT (2*HZ)
 #define SCSI_REPORT_LUNS_TIMEOUT (30*HZ)
 
 /*
  * Prefix values for the SCSI id's (stored in sysfs name field)
  */
 #define SCSI_UID_SER_NUM 'S'
 #define SCSI_UID_UNKNOWN 'Z'
 
 /*
  * Return values of some of the scanning functions.
  *
  * SCSI_SCAN_NO_RESPONSE: no valid response received from the target, this
  * includes allocation or general failures preventing IO from being sent.
  *
  * SCSI_SCAN_TARGET_PRESENT: target responded, but no device is available
  * on the given LUN.
  *
  * SCSI_SCAN_LUN_PRESENT: target responded, and a device is available on a
  * given LUN.
  */
 #define SCSI_SCAN_NO_RESPONSE       0
 #define SCSI_SCAN_TARGET_PRESENT    1
 #define SCSI_SCAN_LUN_PRESENT       2
 
 static const char *scsi_null_device_strs = "nullnullnullnull";
 
 #define MAX_SCSI_LUNS   512
 
 static u64 max_scsi_luns = MAX_SCSI_LUNS;
 
 module_param_named(max_luns, max_scsi_luns, ullong, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(max_luns,
          "last scsi LUN (should be between 1 and 2^64-1)");
 
 #ifdef CONFIG_SCSI_SCAN_ASYNC
 #define SCSI_SCAN_TYPE_DEFAULT "async"
 #else
 #define SCSI_SCAN_TYPE_DEFAULT "sync"
 #endif
 
 static char scsi_scan_type[7] = SCSI_SCAN_TYPE_DEFAULT;
 
 module_param_string(scan, scsi_scan_type, sizeof(scsi_scan_type),
             S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(scan, "sync, async, manual, or none. "
          "Setting to 'manual' disables automatic scanning, but allows "
          "for manual device scan via the 'scan' sysfs attribute.");
 
 static unsigned int scsi_inq_timeout = SCSI_TIMEOUT/HZ + 18;
 
 module_param_named(inq_timeout, scsi_inq_timeout, uint, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(inq_timeout, 
          "Timeout (in seconds) waiting for devices to answer INQUIRY."
          " Default is 20. Some devices may need more; most need less.");
 
 /* This lock protects only this list */
 static DEFINE_SPINLOCK(async_scan_lock);
 static LIST_HEAD(scanning_hosts);
 
 struct async_scan_data {
     struct list_head list;
     struct Scsi_Host *shost;
     struct completion prev_finished;
 };
 
 /*
  * scsi_enable_async_suspend - Enable async suspend and resume
  */
 void scsi_enable_async_suspend(struct device *dev)
 {
     /*
      * If a user has disabled async probing a likely reason is due to a
      * storage enclosure that does not inject staggered spin-ups. For
      * safety, make resume synchronous as well in that case.
      */
     if (strncmp(scsi_scan_type, "async", 5) != 0)
         return;
     /* Enable asynchronous suspend and resume. */
     device_enable_async_suspend(dev);
 }
 
 /**
  * scsi_complete_async_scans - Wait for asynchronous scans to complete
  *
  * When this function returns, any host which started scanning before
  * this function was called will have finished its scan.  Hosts which
  * started scanning after this function was called may or may not have
  * finished.
  */
 int scsi_complete_async_scans(void)
 {
     struct async_scan_data *data;
 
     do {
         if (list_empty(&scanning_hosts))
             return 0;
         /* If we can't get memory immediately, that's OK.  Just
          * sleep a little.  Even if we never get memory, the async
          * scans will finish eventually.
          */
         data = kmalloc(sizeof(*data), GFP_KERNEL);
         if (!data)
             msleep(1);
     } while (!data);
 
     data->shost = NULL;
     init_completion(&data->prev_finished);
 
     spin_lock(&async_scan_lock);
     /* Check that there's still somebody else on the list */
     if (list_empty(&scanning_hosts))
         goto done;
     list_add_tail(&data->list, &scanning_hosts);
     spin_unlock(&async_scan_lock);
 
     printk(KERN_INFO "scsi: waiting for bus probes to complete ...\n");
     wait_for_completion(&data->prev_finished);
 
     spin_lock(&async_scan_lock);
     list_del(&data->list);
     if (!list_empty(&scanning_hosts)) {
         struct async_scan_data *next = list_entry(scanning_hosts.next,
                 struct async_scan_data, list);
         complete(&next->prev_finished);
     }
  done:
     spin_unlock(&async_scan_lock);
 
     kfree(data);
     return 0;
 }
 
 /**
  * scsi_unlock_floptical - unlock device via a special MODE SENSE command
  * @sdev:   scsi device to send command to
  * @result: area to store the result of the MODE SENSE
  *
  * Description:
  *     Send a vendor specific MODE SENSE (not a MODE SELECT) command.
  *     Called for BLIST_KEY devices.
  **/
 static void scsi_unlock_floptical(struct scsi_device *sdev,
                   unsigned char *result)
 {
     unsigned char scsi_cmd[MAX_COMMAND_SIZE];
 
     sdev_printk(KERN_NOTICE, sdev, "unlocking floptical drive\n");
     scsi_cmd[0] = MODE_SENSE;
     scsi_cmd[1] = 0;
     scsi_cmd[2] = 0x2e;
     scsi_cmd[3] = 0;
     scsi_cmd[4] = 0x2a;     /* size */
     scsi_cmd[5] = 0;
     scsi_execute_req(sdev, scsi_cmd, DMA_FROM_DEVICE, result, 0x2a, NULL,
              SCSI_TIMEOUT, 3, NULL);
 }
 
 static int scsi_realloc_sdev_budget_map(struct scsi_device *sdev,
                     unsigned int depth)
 {
     int new_shift = sbitmap_calculate_shift(depth);
     bool need_alloc = !sdev->budget_map.map;
     bool need_free = false;
     int ret;
     struct sbitmap sb_backup;
 
     depth = min_t(unsigned int, depth, scsi_device_max_queue_depth(sdev));
 
     /*
      * realloc if new shift is calculated, which is caused by setting
      * up one new default queue depth after calling ->slave_configure
      */
     if (!need_alloc && new_shift != sdev->budget_map.shift)
         need_alloc = need_free = true;
 
     if (!need_alloc)
         return 0;
 
     /*
      * Request queue has to be frozen for reallocating budget map,
      * and here disk isn't added yet, so freezing is pretty fast
      */
     if (need_free) {
         blk_mq_freeze_queue(sdev->request_queue);
         sb_backup = sdev->budget_map;
     }
     ret = sbitmap_init_node(&sdev->budget_map,
                 scsi_device_max_queue_depth(sdev),
                 new_shift, GFP_KERNEL,
                 sdev->request_queue->node, false, true);
     if (!ret)
         sbitmap_resize(&sdev->budget_map, depth);
 
     if (need_free) {
         if (ret)
             sdev->budget_map = sb_backup;
         else
             sbitmap_free(&sb_backup);
         ret = 0;
         blk_mq_unfreeze_queue(sdev->request_queue);
     }
     return ret;
 }
 
 /**
  * scsi_alloc_sdev - allocate and setup a scsi_Device
  * @starget: which target to allocate a &scsi_device for
  * @lun: which lun
  * @hostdata: usually NULL and set by ->slave_alloc instead
  *
  * Description:
  *     Allocate, initialize for io, and return a pointer to a scsi_Device.
  *     Stores the @shost, @channel, @id, and @lun in the scsi_Device, and
  *     adds scsi_Device to the appropriate list.
  *
  * Return value:
  *     scsi_Device pointer, or NULL on failure.
  **/
 static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
                        u64 lun, void *hostdata)
 {
     unsigned int depth;
     struct scsi_device *sdev;
     struct request_queue *q;
     int display_failure_msg = 1, ret;
     struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 
     sdev = kzalloc(sizeof(*sdev) + shost->transportt->device_size,
                GFP_KERNEL);
     if (!sdev)
         goto out;
 
     sdev->vendor = scsi_null_device_strs;
     sdev->model = scsi_null_device_strs;
     sdev->rev = scsi_null_device_strs;
     sdev->host = shost;
     sdev->queue_ramp_up_period = SCSI_DEFAULT_RAMP_UP_PERIOD;
     sdev->id = starget->id;
     sdev->lun = lun;
     sdev->channel = starget->channel;
     mutex_init(&sdev->state_mutex);
     sdev->sdev_state = SDEV_CREATED;
     INIT_LIST_HEAD(&sdev->siblings);
     INIT_LIST_HEAD(&sdev->same_target_siblings);
     INIT_LIST_HEAD(&sdev->starved_entry);
     INIT_LIST_HEAD(&sdev->event_list);
     spin_lock_init(&sdev->list_lock);
     mutex_init(&sdev->inquiry_mutex);
     INIT_WORK(&sdev->event_work, scsi_evt_thread);
     INIT_WORK(&sdev->requeue_work, scsi_requeue_run_queue);
 
     sdev->sdev_gendev.parent = get_device(&starget->dev);
     sdev->sdev_target = starget;
 
     /* usually NULL and set by ->slave_alloc instead */
     sdev->hostdata = hostdata;
 
     /* if the device needs this changing, it may do so in the
      * slave_configure function */
     sdev->max_device_blocked = SCSI_DEFAULT_DEVICE_BLOCKED;
 
     /*
      * Some low level driver could use device->type
      */
     sdev->type = -1;
 
     /*
      * Assume that the device will have handshaking problems,
      * and then fix this field later if it turns out it
      * doesn't
      */
     sdev->borken = 1;
 
     sdev->sg_reserved_size = INT_MAX;
 
     q = blk_mq_init_queue(&sdev->host->tag_set);
     if (IS_ERR(q)) {
         /* release fn is set up in scsi_sysfs_device_initialise, so
          * have to free and put manually here */
         put_device(&starget->dev);
         kfree(sdev);
         goto out;
     }
     kref_get(&sdev->host->tagset_refcnt);
     sdev->request_queue = q;
     q->queuedata = sdev;
     __scsi_init_queue(sdev->host, q);
     WARN_ON_ONCE(!blk_get_queue(q));
 
     depth = sdev->host->cmd_per_lun ?: 1;
 
     /*
      * Use .can_queue as budget map's depth because we have to
      * support adjusting queue depth from sysfs. Meantime use
      * default device queue depth to figure out sbitmap shift
      * since we use this queue depth most of times.
      */
     if (scsi_realloc_sdev_budget_map(sdev, depth)) {
         put_device(&starget->dev);
         kfree(sdev);
         goto out;
     }
 
     scsi_change_queue_depth(sdev, depth);
 
     scsi_sysfs_device_initialize(sdev);
 
     if (shost->hostt->slave_alloc) {
         ret = shost->hostt->slave_alloc(sdev);
         if (ret) {
             /*
              * if LLDD reports slave not present, don't clutter
              * console with alloc failure messages
              */
             if (ret == -ENXIO)
                 display_failure_msg = 0;
             goto out_device_destroy;
         }
     }
 
     return sdev;
 
 out_device_destroy:
     __scsi_remove_device(sdev);
 out:
     if (display_failure_msg)
         printk(ALLOC_FAILURE_MSG, __func__);
     return NULL;
 }
 
 static void scsi_target_destroy(struct scsi_target *starget)
 {
     struct device *dev = &starget->dev;
     struct Scsi_Host *shost = dev_to_shost(dev->parent);
     unsigned long flags;
 
     BUG_ON(starget->state == STARGET_DEL);
     starget->state = STARGET_DEL;
     transport_destroy_device(dev);
     spin_lock_irqsave(shost->host_lock, flags);
     if (shost->hostt->target_destroy)
         shost->hostt->target_destroy(starget);
     list_del_init(&starget->siblings);
     spin_unlock_irqrestore(shost->host_lock, flags);
     put_device(dev);
 }
 
 static void scsi_target_dev_release(struct device *dev)
 {
     struct device *parent = dev->parent;
     struct scsi_target *starget = to_scsi_target(dev);
 
     kfree(starget);
     put_device(parent);
 }
 
 static struct device_type scsi_target_type = {
     .name =     "scsi_target",
     .release =  scsi_target_dev_release,
 };
 
 int scsi_is_target_device(const struct device *dev)
 {
     return dev->type == &scsi_target_type;
 }
 EXPORT_SYMBOL(scsi_is_target_device);
 
 static struct scsi_target *__scsi_find_target(struct device *parent,
                           int channel, uint id)
 {
     struct scsi_target *starget, *found_starget = NULL;
     struct Scsi_Host *shost = dev_to_shost(parent);
     /*
      * Search for an existing target for this sdev.
      */
     list_for_each_entry(starget, &shost->__targets, siblings) {
         if (starget->id == id &&
             starget->channel == channel) {
             found_starget = starget;
             break;
         }
     }
     if (found_starget)
         get_device(&found_starget->dev);
 
     return found_starget;
 }
 
 /**
  * scsi_target_reap_ref_release - remove target from visibility
  * @kref: the reap_ref in the target being released
  *
  * Called on last put of reap_ref, which is the indication that no device
  * under this target is visible anymore, so render the target invisible in
  * sysfs.  Note: we have to be in user context here because the target reaps
  * should be done in places where the scsi device visibility is being removed.
  */
 static void scsi_target_reap_ref_release(struct kref *kref)
 {
     struct scsi_target *starget
         = container_of(kref, struct scsi_target, reap_ref);
 
     /*
      * if we get here and the target is still in a CREATED state that
      * means it was allocated but never made visible (because a scan
      * turned up no LUNs), so don't call device_del() on it.
      */
     if ((starget->state != STARGET_CREATED) &&
         (starget->state != STARGET_CREATED_REMOVE)) {
         transport_remove_device(&starget->dev);
         device_del(&starget->dev);
     }
     scsi_target_destroy(starget);
 }
 
 static void scsi_target_reap_ref_put(struct scsi_target *starget)
 {
     kref_put(&starget->reap_ref, scsi_target_reap_ref_release);
 }
 
 /**
  * scsi_alloc_target - allocate a new or find an existing target
  * @parent: parent of the target (need not be a scsi host)
  * @channel:    target channel number (zero if no channels)
  * @id:     target id number
  *
  * Return an existing target if one exists, provided it hasn't already
  * gone into STARGET_DEL state, otherwise allocate a new target.
  *
  * The target is returned with an incremented reference, so the caller
  * is responsible for both reaping and doing a last put
  */
 static struct scsi_target *scsi_alloc_target(struct device *parent,
                          int channel, uint id)
 {
     struct Scsi_Host *shost = dev_to_shost(parent);
     struct device *dev = NULL;
     unsigned long flags;
     const int size = sizeof(struct scsi_target)
         + shost->transportt->target_size;
     struct scsi_target *starget;
     struct scsi_target *found_target;
     int error, ref_got;
 
     starget = kzalloc(size, GFP_KERNEL);
     if (!starget) {
         printk(KERN_ERR "%s: allocation failure\n", __func__);
         return NULL;
     }
     dev = &starget->dev;
     device_initialize(dev);
     kref_init(&starget->reap_ref);
     dev->parent = get_device(parent);
     dev_set_name(dev, "target%d:%d:%d", shost->host_no, channel, id);
     dev->bus = &scsi_bus_type;
     dev->type = &scsi_target_type;
     scsi_enable_async_suspend(dev);
     starget->id = id;
     starget->channel = channel;
     starget->can_queue = 0;
     INIT_LIST_HEAD(&starget->siblings);
     INIT_LIST_HEAD(&starget->devices);
     starget->state = STARGET_CREATED;
     starget->scsi_level = SCSI_2;
     starget->max_target_blocked = SCSI_DEFAULT_TARGET_BLOCKED;
  retry:
     spin_lock_irqsave(shost->host_lock, flags);
 
     found_target = __scsi_find_target(parent, channel, id);
     if (found_target)
         goto found;
 
     list_add_tail(&starget->siblings, &shost->__targets);
     spin_unlock_irqrestore(shost->host_lock, flags);
     /* allocate and add */
     transport_setup_device(dev);
     if (shost->hostt->target_alloc) {
         error = shost->hostt->target_alloc(starget);
 
         if(error) {
             if (error != -ENXIO)
                 dev_err(dev, "target allocation failed, error %d\n", error);
             /* don't want scsi_target_reap to do the final
              * put because it will be under the host lock */
             scsi_target_destroy(starget);
             return NULL;
         }
     }
     get_device(dev);
 
     return starget;
 
  found:
     /*
      * release routine already fired if kref is zero, so if we can still
      * take the reference, the target must be alive.  If we can't, it must
      * be dying and we need to wait for a new target
      */
     ref_got = kref_get_unless_zero(&found_target->reap_ref);
 
     spin_unlock_irqrestore(shost->host_lock, flags);
     if (ref_got) {
         put_device(dev);
         return found_target;
     }
     /*
      * Unfortunately, we found a dying target; need to wait until it's
      * dead before we can get a new one.  There is an anomaly here.  We
      * *should* call scsi_target_reap() to balance the kref_get() of the
      * reap_ref above.  However, since the target being released, it's
      * already invisible and the reap_ref is irrelevant.  If we call
      * scsi_target_reap() we might spuriously do another device_del() on
      * an already invisible target.
      */
     put_device(&found_target->dev);
     /*
      * length of time is irrelevant here, we just want to yield the CPU
      * for a tick to avoid busy waiting for the target to die.
      */
     msleep(1);
     goto retry;
 }
 
 /**
  * scsi_target_reap - check to see if target is in use and destroy if not
  * @starget: target to be checked
  *
  * This is used after removing a LUN or doing a last put of the target
  * it checks atomically that nothing is using the target and removes
  * it if so.
  */
 void scsi_target_reap(struct scsi_target *starget)
 {
     /*
      * serious problem if this triggers: STARGET_DEL is only set in the if
      * the reap_ref drops to zero, so we're trying to do another final put
      * on an already released kref
      */
     BUG_ON(starget->state == STARGET_DEL);
     scsi_target_reap_ref_put(starget);
 }
 
 /**
  * scsi_sanitize_inquiry_string - remove non-graphical chars from an
  *                                INQUIRY result string
  * @s: INQUIRY result string to sanitize
  * @len: length of the string
  *
  * Description:
  *  The SCSI spec says that INQUIRY vendor, product, and revision
  *  strings must consist entirely of graphic ASCII characters,
  *  padded on the right with spaces.  Since not all devices obey
  *  this rule, we will replace non-graphic or non-ASCII characters
  *  with spaces.  Exception: a NUL character is interpreted as a
  *  string terminator, so all the following characters are set to
  *  spaces.
  **/
 void scsi_sanitize_inquiry_string(unsigned char *s, int len)
 {
     int terminated = 0;
 
     for (; len > 0; (--len, ++s)) {
         if (*s == 0)
             terminated = 1;
         if (terminated || *s < 0x20 || *s > 0x7e)
             *s = ' ';
     }
 }
 EXPORT_SYMBOL(scsi_sanitize_inquiry_string);
 
 /**
  * scsi_probe_lun - probe a single LUN using a SCSI INQUIRY
  * @sdev:   scsi_device to probe
  * @inq_result: area to store the INQUIRY result
  * @result_len: len of inq_result
  * @bflags: store any bflags found here
  *
  * Description:
  *     Probe the lun associated with @req using a standard SCSI INQUIRY;
  *
  *     If the INQUIRY is successful, zero is returned and the
  *     INQUIRY data is in @inq_result; the scsi_level and INQUIRY length
  *     are copied to the scsi_device any flags value is stored in *@bflags.
  **/
 static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result,
               int result_len, blist_flags_t *bflags)
 {
     unsigned char scsi_cmd[MAX_COMMAND_SIZE];
     int first_inquiry_len, try_inquiry_len, next_inquiry_len;
     int response_len = 0;
     int pass, count, result;
     struct scsi_sense_hdr sshdr;
 
     *bflags = 0;
 
     /* Perform up to 3 passes.  The first pass uses a conservative
      * transfer length of 36 unless sdev->inquiry_len specifies a
      * different value. */
     first_inquiry_len = sdev->inquiry_len ? sdev->inquiry_len : 36;
     try_inquiry_len = first_inquiry_len;
     pass = 1;
 
  next_pass:
     SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
                 "scsi scan: INQUIRY pass %d length %d\n",
                 pass, try_inquiry_len));
 
     /* Each pass gets up to three chances to ignore Unit Attention */
     for (count = 0; count < 3; ++count) {
         int resid;
 
         memset(scsi_cmd, 0, 6);
         scsi_cmd[0] = INQUIRY;
         scsi_cmd[4] = (unsigned char) try_inquiry_len;
 
         memset(inq_result, 0, try_inquiry_len);
 
         result = scsi_execute_req(sdev,  scsi_cmd, DMA_FROM_DEVICE,
                       inq_result, try_inquiry_len, &sshdr,
                       HZ / 2 + HZ * scsi_inq_timeout, 3,
                       &resid);
 
         SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
                 "scsi scan: INQUIRY %s with code 0x%x\n",
                 result ? "failed" : "successful", result));
 
         if (result > 0) {
             /*
              * not-ready to ready transition [asc/ascq=0x28/0x0]
              * or power-on, reset [asc/ascq=0x29/0x0], continue.
              * INQUIRY should not yield UNIT_ATTENTION
              * but many buggy devices do so anyway. 
              */
             if (scsi_status_is_check_condition(result) &&
                 scsi_sense_valid(&sshdr)) {
                 if ((sshdr.sense_key == UNIT_ATTENTION) &&
                     ((sshdr.asc == 0x28) ||
                      (sshdr.asc == 0x29)) &&
                     (sshdr.ascq == 0))
                     continue;
             }
         } else if (result == 0) {
             /*
              * if nothing was transferred, we try
              * again. It's a workaround for some USB
              * devices.
              */
             if (resid == try_inquiry_len)
                 continue;
         }
         break;
     }
 
     if (result == 0) {
         scsi_sanitize_inquiry_string(&inq_result[8], 8);
         scsi_sanitize_inquiry_string(&inq_result[16], 16);
         scsi_sanitize_inquiry_string(&inq_result[32], 4);
 
         response_len = inq_result[4] + 5;
         if (response_len > 255)
             response_len = first_inquiry_len;   /* sanity */
 
         /*
          * Get any flags for this device.
          *
          * XXX add a bflags to scsi_device, and replace the
          * corresponding bit fields in scsi_device, so bflags
          * need not be passed as an argument.
          */
         *bflags = scsi_get_device_flags(sdev, &inq_result[8],
                 &inq_result[16]);
 
         /* When the first pass succeeds we gain information about
          * what larger transfer lengths might work. */
         if (pass == 1) {
             if (BLIST_INQUIRY_36 & *bflags)
                 next_inquiry_len = 36;
             /*
              * LLD specified a maximum sdev->inquiry_len
              * but device claims it has more data. Capping
              * the length only makes sense for legacy
              * devices. If a device supports SPC-4 (2014)
              * or newer, assume that it is safe to ask for
              * as much as the device says it supports.
              */
             else if (sdev->inquiry_len &&
                  response_len > sdev->inquiry_len &&
                  (inq_result[2] & 0x7) < 6) /* SPC-4 */
                 next_inquiry_len = sdev->inquiry_len;
             else
                 next_inquiry_len = response_len;
 
             /* If more data is available perform the second pass */
             if (next_inquiry_len > try_inquiry_len) {
                 try_inquiry_len = next_inquiry_len;
                 pass = 2;
                 goto next_pass;
             }
         }
 
     } else if (pass == 2) {
         sdev_printk(KERN_INFO, sdev,
                 "scsi scan: %d byte inquiry failed.  "
                 "Consider BLIST_INQUIRY_36 for this device\n",
                 try_inquiry_len);
 
         /* If this pass failed, the third pass goes back and transfers
          * the same amount as we successfully got in the first pass. */
         try_inquiry_len = first_inquiry_len;
         pass = 3;
         goto next_pass;
     }
 
     /* If the last transfer attempt got an error, assume the
      * peripheral doesn't exist or is dead. */
     if (result)
         return -EIO;
 
     /* Don't report any more data than the device says is valid */
     sdev->inquiry_len = min(try_inquiry_len, response_len);
 
     /*
      * XXX Abort if the response length is less than 36? If less than
      * 32, the lookup of the device flags (above) could be invalid,
      * and it would be possible to take an incorrect action - we do
      * not want to hang because of a short INQUIRY. On the flip side,
      * if the device is spun down or becoming ready (and so it gives a
      * short INQUIRY), an abort here prevents any further use of the
      * device, including spin up.
      *
      * On the whole, the best approach seems to be to assume the first
      * 36 bytes are valid no matter what the device says.  That's
      * better than copying < 36 bytes to the inquiry-result buffer
      * and displaying garbage for the Vendor, Product, or Revision
      * strings.
      */
     if (sdev->inquiry_len < 36) {
         if (!sdev->host->short_inquiry) {
             shost_printk(KERN_INFO, sdev->host,
                     "scsi scan: INQUIRY result too short (%d),"
                     " using 36\n", sdev->inquiry_len);
             sdev->host->short_inquiry = 1;
         }
         sdev->inquiry_len = 36;
     }
 
     /*
      * Related to the above issue:
      *
      * XXX Devices (disk or all?) should be sent a TEST UNIT READY,
      * and if not ready, sent a START_STOP to start (maybe spin up) and
      * then send the INQUIRY again, since the INQUIRY can change after
      * a device is initialized.
      *
      * Ideally, start a device if explicitly asked to do so.  This
      * assumes that a device is spun up on power on, spun down on
      * request, and then spun up on request.
      */
 
     /*
      * The scanning code needs to know the scsi_level, even if no
      * device is attached at LUN 0 (SCSI_SCAN_TARGET_PRESENT) so
      * non-zero LUNs can be scanned.
      */
     sdev->scsi_level = inq_result[2] & 0x07;
     if (sdev->scsi_level >= 2 ||
         (sdev->scsi_level == 1 && (inq_result[3] & 0x0f) == 1))
         sdev->scsi_level++;
     sdev->sdev_target->scsi_level = sdev->scsi_level;
 
     /*
      * If SCSI-2 or lower, and if the transport requires it,
      * store the LUN value in CDB[1].
      */
     sdev->lun_in_cdb = 0;
     if (sdev->scsi_level <= SCSI_2 &&
         sdev->scsi_level != SCSI_UNKNOWN &&
         !sdev->host->no_scsi2_lun_in_cdb)
         sdev->lun_in_cdb = 1;
 
     return 0;
 }
 
 /**
  * scsi_add_lun - allocate and fully initialze a scsi_device
  * @sdev:   holds information to be stored in the new scsi_device
  * @inq_result: holds the result of a previous INQUIRY to the LUN
  * @bflags: black/white list flag
  * @async:  1 if this device is being scanned asynchronously
  *
  * Description:
  *     Initialize the scsi_device @sdev.  Optionally set fields based
  *     on values in *@bflags.
  *
  * Return:
  *     SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
  *     SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
  **/
 static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
         blist_flags_t *bflags, int async)
 {
     int ret;
 
     /*
      * XXX do not save the inquiry, since it can change underneath us,
      * save just vendor/model/rev.
      *
      * Rather than save it and have an ioctl that retrieves the saved
      * value, have an ioctl that executes the same INQUIRY code used
      * in scsi_probe_lun, let user level programs doing INQUIRY
      * scanning run at their own risk, or supply a user level program
      * that can correctly scan.
      */
 
     /*
      * Copy at least 36 bytes of INQUIRY data, so that we don't
      * dereference unallocated memory when accessing the Vendor,
      * Product, and Revision strings.  Badly behaved devices may set
      * the INQUIRY Additional Length byte to a small value, indicating
      * these strings are invalid, but often they contain plausible data
      * nonetheless.  It doesn't matter if the device sent < 36 bytes
      * total, since scsi_probe_lun() initializes inq_result with 0s.
      */
     sdev->inquiry = kmemdup(inq_result,
                 max_t(size_t, sdev->inquiry_len, 36),
                 GFP_KERNEL);
     if (sdev->inquiry == NULL)
         return SCSI_SCAN_NO_RESPONSE;
 
     sdev->vendor = (char *) (sdev->inquiry + 8);
     sdev->model = (char *) (sdev->inquiry + 16);
     sdev->rev = (char *) (sdev->inquiry + 32);
 
     if (strncmp(sdev->vendor, "ATA     ", 8) == 0) {
         /*
          * sata emulation layer device.  This is a hack to work around
          * the SATL power management specifications which state that
          * when the SATL detects the device has gone into standby
          * mode, it shall respond with NOT READY.
          */
         sdev->allow_restart = 1;
     }
 
     if (*bflags & BLIST_ISROM) {
         sdev->type = TYPE_ROM;
         sdev->removable = 1;
     } else {
         sdev->type = (inq_result[0] & 0x1f);
         sdev->removable = (inq_result[1] & 0x80) >> 7;
 
         /*
          * some devices may respond with wrong type for
          * well-known logical units. Force well-known type
          * to enumerate them correctly.
          */
         if (scsi_is_wlun(sdev->lun) && sdev->type != TYPE_WLUN) {
             sdev_printk(KERN_WARNING, sdev,
                 "%s: correcting incorrect peripheral device type 0x%x for W-LUN 0x%16xhN\n",
                 __func__, sdev->type, (unsigned int)sdev->lun);
             sdev->type = TYPE_WLUN;
         }
 
     }
 
     if (sdev->type == TYPE_RBC || sdev->type == TYPE_ROM) {
         /* RBC and MMC devices can return SCSI-3 compliance and yet
          * still not support REPORT LUNS, so make them act as
          * BLIST_NOREPORTLUN unless BLIST_REPORTLUN2 is
          * specifically set */
         if ((*bflags & BLIST_REPORTLUN2) == 0)
             *bflags |= BLIST_NOREPORTLUN;
     }
 
     /*
      * For a peripheral qualifier (PQ) value of 1 (001b), the SCSI
      * spec says: The device server is capable of supporting the
      * specified peripheral device type on this logical unit. However,
      * the physical device is not currently connected to this logical
      * unit.
      *
      * The above is vague, as it implies that we could treat 001 and
      * 011 the same. Stay compatible with previous code, and create a
      * scsi_device for a PQ of 1
      *
      * Don't set the device offline here; rather let the upper
      * level drivers eval the PQ to decide whether they should
      * attach. So remove ((inq_result[0] >> 5) & 7) == 1 check.
      */ 
 
     sdev->inq_periph_qual = (inq_result[0] >> 5) & 7;
     sdev->lockable = sdev->removable;
     sdev->soft_reset = (inq_result[7] & 1) && ((inq_result[3] & 7) == 2);
 
     if (sdev->scsi_level >= SCSI_3 ||
             (sdev->inquiry_len > 56 && inq_result[56] & 0x04))
         sdev->ppr = 1;
     if (inq_result[7] & 0x60)
         sdev->wdtr = 1;
     if (inq_result[7] & 0x10)
         sdev->sdtr = 1;
 
     sdev_printk(KERN_NOTICE, sdev, "%s %.8s %.16s %.4s PQ: %d "
             "ANSI: %d%s\n", scsi_device_type(sdev->type),
             sdev->vendor, sdev->model, sdev->rev,
             sdev->inq_periph_qual, inq_result[2] & 0x07,
             (inq_result[3] & 0x0f) == 1 ? " CCS" : "");
 
     if ((sdev->scsi_level >= SCSI_2) && (inq_result[7] & 2) &&
         !(*bflags & BLIST_NOTQ)) {
         sdev->tagged_supported = 1;
         sdev->simple_tags = 1;
     }
 
     /*
      * Some devices (Texel CD ROM drives) have handshaking problems
      * when used with the Seagate controllers. borken is initialized
      * to 1, and then set it to 0 here.
      */
     if ((*bflags & BLIST_BORKEN) == 0)
         sdev->borken = 0;
 
     if (*bflags & BLIST_NO_ULD_ATTACH)
         sdev->no_uld_attach = 1;
 
     /*
      * Apparently some really broken devices (contrary to the SCSI
      * standards) need to be selected without asserting ATN
      */
     if (*bflags & BLIST_SELECT_NO_ATN)
         sdev->select_no_atn = 1;
 
     /*
      * Maximum 512 sector transfer length
      * broken RA4x00 Compaq Disk Array
      */
     if (*bflags & BLIST_MAX_512)
         blk_queue_max_hw_sectors(sdev->request_queue, 512);
     /*
      * Max 1024 sector transfer length for targets that report incorrect
      * max/optimal lengths and relied on the old block layer safe default
      */
     else if (*bflags & BLIST_MAX_1024)
         blk_queue_max_hw_sectors(sdev->request_queue, 1024);
 
     /*
      * Some devices may not want to have a start command automatically
      * issued when a device is added.
      */
     if (*bflags & BLIST_NOSTARTONADD)
         sdev->no_start_on_add = 1;
 
     if (*bflags & BLIST_SINGLELUN)
         scsi_target(sdev)->single_lun = 1;
 
     sdev->use_10_for_rw = 1;
 
     /* some devices don't like REPORT SUPPORTED OPERATION CODES
      * and will simply timeout causing sd_mod init to take a very
      * very long time */
     if (*bflags & BLIST_NO_RSOC)
         sdev->no_report_opcodes = 1;
 
     /* set the device running here so that slave configure
      * may do I/O */
     mutex_lock(&sdev->state_mutex);
     ret = scsi_device_set_state(sdev, SDEV_RUNNING);
     if (ret)
         ret = scsi_device_set_state(sdev, SDEV_BLOCK);
     mutex_unlock(&sdev->state_mutex);
 
     if (ret) {
         sdev_printk(KERN_ERR, sdev,
                 "in wrong state %s to complete scan\n",
                 scsi_device_state_name(sdev->sdev_state));
         return SCSI_SCAN_NO_RESPONSE;
     }
 
     if (*bflags & BLIST_NOT_LOCKABLE)
         sdev->lockable = 0;
 
     if (*bflags & BLIST_RETRY_HWERROR)
         sdev->retry_hwerror = 1;
 
     if (*bflags & BLIST_NO_DIF)
         sdev->no_dif = 1;
 
     if (*bflags & BLIST_UNMAP_LIMIT_WS)
         sdev->unmap_limit_for_ws = 1;
 
     if (*bflags & BLIST_IGN_MEDIA_CHANGE)
         sdev->ignore_media_change = 1;
 
     sdev->eh_timeout = SCSI_DEFAULT_EH_TIMEOUT;
 
     if (*bflags & BLIST_TRY_VPD_PAGES)
         sdev->try_vpd_pages = 1;
     else if (*bflags & BLIST_SKIP_VPD_PAGES)
         sdev->skip_vpd_pages = 1;
 
     transport_configure_device(&sdev->sdev_gendev);
 
     if (sdev->host->hostt->slave_configure) {
         ret = sdev->host->hostt->slave_configure(sdev);
         if (ret) {
             /*
              * if LLDD reports slave not present, don't clutter
              * console with alloc failure messages
              */
             if (ret != -ENXIO) {
                 sdev_printk(KERN_ERR, sdev,
                     "failed to configure device\n");
             }
             return SCSI_SCAN_NO_RESPONSE;
         }
 
         /*
          * The queue_depth is often changed in ->slave_configure.
          * Set up budget map again since memory consumption of
          * the map depends on actual queue depth.
          */
         scsi_realloc_sdev_budget_map(sdev, sdev->queue_depth);
     }
 
     if (sdev->scsi_level >= SCSI_3)
         scsi_attach_vpd(sdev);
 
     sdev->max_queue_depth = sdev->queue_depth;
     WARN_ON_ONCE(sdev->max_queue_depth > sdev->budget_map.depth);
     sdev->sdev_bflags = *bflags;
 
     /*
      * Ok, the device is now all set up, we can
      * register it and tell the rest of the kernel
      * about it.
      */
     if (!async && scsi_sysfs_add_sdev(sdev) != 0)
         return SCSI_SCAN_NO_RESPONSE;
 
     return SCSI_SCAN_LUN_PRESENT;
 }
 
 #ifdef CONFIG_SCSI_LOGGING
 /** 
  * scsi_inq_str - print INQUIRY data from min to max index, strip trailing whitespace
  * @buf:   Output buffer with at least end-first+1 bytes of space
  * @inq:   Inquiry buffer (input)
  * @first: Offset of string into inq
  * @end:   Index after last character in inq
  */
 static unsigned char *scsi_inq_str(unsigned char *buf, unsigned char *inq,
                    unsigned first, unsigned end)
 {
     unsigned term = 0, idx;
 
     for (idx = 0; idx + first < end && idx + first < inq[4] + 5; idx++) {
         if (inq[idx+first] > ' ') {
             buf[idx] = inq[idx+first];
             term = idx+1;
         } else {
             buf[idx] = ' ';
         }
     }
     buf[term] = 0;
     return buf;
 }
 #endif
 
 /**
  * scsi_probe_and_add_lun - probe a LUN, if a LUN is found add it
  * @starget:    pointer to target device structure
  * @lun:    LUN of target device
  * @bflagsp:    store bflags here if not NULL
  * @sdevp:  probe the LUN corresponding to this scsi_device
  * @rescan:     if not equal to SCSI_SCAN_INITIAL skip some code only
  *              needed on first scan
  * @hostdata:   passed to scsi_alloc_sdev()
  *
  * Description:
  *     Call scsi_probe_lun, if a LUN with an attached device is found,
  *     allocate and set it up by calling scsi_add_lun.
  *
  * Return:
  *
  *   - SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
  *   - SCSI_SCAN_TARGET_PRESENT: target responded, but no device is
  *         attached at the LUN
  *   - SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
  **/
 static int scsi_probe_and_add_lun(struct scsi_target *starget,
                   u64 lun, blist_flags_t *bflagsp,
                   struct scsi_device **sdevp,
                   enum scsi_scan_mode rescan,
                   void *hostdata)
 {
     struct scsi_device *sdev;
     unsigned char *result;
     blist_flags_t bflags;
     int res = SCSI_SCAN_NO_RESPONSE, result_len = 256;
     struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 
     /*
      * The rescan flag is used as an optimization, the first scan of a
      * host adapter calls into here with rescan == 0.
      */
     sdev = scsi_device_lookup_by_target(starget, lun);
     if (sdev) {
         if (rescan != SCSI_SCAN_INITIAL || !scsi_device_created(sdev)) {
             SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
                 "scsi scan: device exists on %s\n",
                 dev_name(&sdev->sdev_gendev)));
             if (sdevp)
                 *sdevp = sdev;
             else
                 scsi_device_put(sdev);
 
             if (bflagsp)
                 *bflagsp = scsi_get_device_flags(sdev,
                                  sdev->vendor,
                                  sdev->model);
             return SCSI_SCAN_LUN_PRESENT;
         }
         scsi_device_put(sdev);
     } else
         sdev = scsi_alloc_sdev(starget, lun, hostdata);
     if (!sdev)
         goto out;
 
     result = kmalloc(result_len, GFP_KERNEL);
     if (!result)
         goto out_free_sdev;
 
     if (scsi_probe_lun(sdev, result, result_len, &bflags))
         goto out_free_result;
 
     if (bflagsp)
         *bflagsp = bflags;
     /*
      * result contains valid SCSI INQUIRY data.
      */
     if ((result[0] >> 5) == 3) {
         /*
          * For a Peripheral qualifier 3 (011b), the SCSI
          * spec says: The device server is not capable of
          * supporting a physical device on this logical
          * unit.
          *
          * For disks, this implies that there is no
          * logical disk configured at sdev->lun, but there
          * is a target id responding.
          */
         SCSI_LOG_SCAN_BUS(2, sdev_printk(KERN_INFO, sdev, "scsi scan:"
                    " peripheral qualifier of 3, device not"
                    " added\n"))
         if (lun == 0) {
             SCSI_LOG_SCAN_BUS(1, {
                 unsigned char vend[9];
                 unsigned char mod[17];
 
                 sdev_printk(KERN_INFO, sdev,
                     "scsi scan: consider passing scsi_mod."
                     "dev_flags=%s:%s:0x240 or 0x1000240\n",
                     scsi_inq_str(vend, result, 8, 16),
                     scsi_inq_str(mod, result, 16, 32));
             });
 
         }
 
         res = SCSI_SCAN_TARGET_PRESENT;
         goto out_free_result;
     }
 
     /*
      * Some targets may set slight variations of PQ and PDT to signal
      * that no LUN is present, so don't add sdev in these cases.
      * Two specific examples are:
      * 1) NetApp targets: return PQ=1, PDT=0x1f
      * 2) IBM/2145 targets: return PQ=1, PDT=0
      * 3) USB UFI: returns PDT=0x1f, with the PQ bits being "reserved"
      *    in the UFI 1.0 spec (we cannot rely on reserved bits).
      *
      * References:
      * 1) SCSI SPC-3, pp. 145-146
      * PQ=1: "A peripheral device having the specified peripheral
      * device type is not connected to this logical unit. However, the
      * device server is capable of supporting the specified peripheral
      * device type on this logical unit."
      * PDT=0x1f: "Unknown or no device type"
      * 2) USB UFI 1.0, p. 20
      * PDT=00h Direct-access device (floppy)
      * PDT=1Fh none (no FDD connected to the requested logical unit)
      */
     if (((result[0] >> 5) == 1 ||
         (starget->pdt_1f_for_no_lun && (result[0] & 0x1f) == 0x1f)) &&
         !scsi_is_wlun(lun)) {
         SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
                     "scsi scan: peripheral device type"
                     " of 31, no device added\n"));
         res = SCSI_SCAN_TARGET_PRESENT;
         goto out_free_result;
     }
 
     res = scsi_add_lun(sdev, result, &bflags, shost->async_scan);
     if (res == SCSI_SCAN_LUN_PRESENT) {
         if (bflags & BLIST_KEY) {
             sdev->lockable = 0;
             scsi_unlock_floptical(sdev, result);
         }
     }
 
  out_free_result:
     kfree(result);
  out_free_sdev:
     if (res == SCSI_SCAN_LUN_PRESENT) {
         if (sdevp) {
             if (scsi_device_get(sdev) == 0) {
                 *sdevp = sdev;
             } else {
                 __scsi_remove_device(sdev);
                 res = SCSI_SCAN_NO_RESPONSE;
             }
         }
     } else
         __scsi_remove_device(sdev);
  out:
     return res;
 }
 
 /**
  * scsi_sequential_lun_scan - sequentially scan a SCSI target
  * @starget:    pointer to target structure to scan
  * @bflags: black/white list flag for LUN 0
  * @scsi_level: Which version of the standard does this device adhere to
  * @rescan:     passed to scsi_probe_add_lun()
  *
  * Description:
  *     Generally, scan from LUN 1 (LUN 0 is assumed to already have been
  *     scanned) to some maximum lun until a LUN is found with no device
  *     attached. Use the bflags to figure out any oddities.
  *
  *     Modifies sdevscan->lun.
  **/
 static void scsi_sequential_lun_scan(struct scsi_target *starget,
                      blist_flags_t bflags, int scsi_level,
                      enum scsi_scan_mode rescan)
 {
     uint max_dev_lun;
     u64 sparse_lun, lun;
     struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 
     SCSI_LOG_SCAN_BUS(3, starget_printk(KERN_INFO, starget,
         "scsi scan: Sequential scan\n"));
 
     max_dev_lun = min(max_scsi_luns, shost->max_lun);
     /*
      * If this device is known to support sparse multiple units,
      * override the other settings, and scan all of them. Normally,
      * SCSI-3 devices should be scanned via the REPORT LUNS.
      */
     if (bflags & BLIST_SPARSELUN) {
         max_dev_lun = shost->max_lun;
         sparse_lun = 1;
     } else
         sparse_lun = 0;
 
     /*
      * If less than SCSI_1_CCS, and no special lun scanning, stop
      * scanning; this matches 2.4 behaviour, but could just be a bug
      * (to continue scanning a SCSI_1_CCS device).
      *
      * This test is broken.  We might not have any device on lun0 for
      * a sparselun device, and if that's the case then how would we
      * know the real scsi_level, eh?  It might make sense to just not
      * scan any SCSI_1 device for non-0 luns, but that check would best
      * go into scsi_alloc_sdev() and just have it return null when asked
      * to alloc an sdev for lun > 0 on an already found SCSI_1 device.
      *
     if ((sdevscan->scsi_level < SCSI_1_CCS) &&
         ((bflags & (BLIST_FORCELUN | BLIST_SPARSELUN | BLIST_MAX5LUN))
          == 0))
         return;
      */
     /*
      * If this device is known to support multiple units, override
      * the other settings, and scan all of them.
      */
     if (bflags & BLIST_FORCELUN)
         max_dev_lun = shost->max_lun;
     /*
      * REGAL CDC-4X: avoid hang after LUN 4
      */
     if (bflags & BLIST_MAX5LUN)
         max_dev_lun = min(5U, max_dev_lun);
     /*
      * Do not scan SCSI-2 or lower device past LUN 7, unless
      * BLIST_LARGELUN.
      */
     if (scsi_level < SCSI_3 && !(bflags & BLIST_LARGELUN))
         max_dev_lun = min(8U, max_dev_lun);
     else
         max_dev_lun = min(256U, max_dev_lun);
 
     /*
      * We have already scanned LUN 0, so start at LUN 1. Keep scanning
      * until we reach the max, or no LUN is found and we are not
      * sparse_lun.
      */
     for (lun = 1; lun < max_dev_lun; ++lun)
         if ((scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan,
                         NULL) != SCSI_SCAN_LUN_PRESENT) &&
             !sparse_lun)
             return;
 }
 
 /**
  * scsi_report_lun_scan - Scan using SCSI REPORT LUN results
  * @starget: which target
  * @bflags: Zero or a mix of BLIST_NOLUN, BLIST_REPORTLUN2, or BLIST_NOREPORTLUN
  * @rescan: nonzero if we can skip code only needed on first scan
  *
  * Description:
  *   Fast scanning for modern (SCSI-3) devices by sending a REPORT LUN command.
  *   Scan the resulting list of LUNs by calling scsi_probe_and_add_lun.
  *
  *   If BLINK_REPORTLUN2 is set, scan a target that supports more than 8
  *   LUNs even if it's older than SCSI-3.
  *   If BLIST_NOREPORTLUN is set, return 1 always.
  *   If BLIST_NOLUN is set, return 0 always.
  *   If starget->no_report_luns is set, return 1 always.
  *
  * Return:
  *     0: scan completed (or no memory, so further scanning is futile)
  *     1: could not scan with REPORT LUN
  **/
 static int scsi_report_lun_scan(struct scsi_target *starget, blist_flags_t bflags,
                 enum scsi_scan_mode rescan)
 {
     unsigned char scsi_cmd[MAX_COMMAND_SIZE];
     unsigned int length;
     u64 lun;
     unsigned int num_luns;
     unsigned int retries;
     int result;
     struct scsi_lun *lunp, *lun_data;
     struct scsi_sense_hdr sshdr;
     struct scsi_device *sdev;
     struct Scsi_Host *shost = dev_to_shost(&starget->dev);
     int ret = 0;
 
     /*
      * Only support SCSI-3 and up devices if BLIST_NOREPORTLUN is not set.
      * Also allow SCSI-2 if BLIST_REPORTLUN2 is set and host adapter does
      * support more than 8 LUNs.
      * Don't attempt if the target doesn't support REPORT LUNS.
      */
     if (bflags & BLIST_NOREPORTLUN)
         return 1;
     if (starget->scsi_level < SCSI_2 &&
         starget->scsi_level != SCSI_UNKNOWN)
         return 1;
     if (starget->scsi_level < SCSI_3 &&
         (!(bflags & BLIST_REPORTLUN2) || shost->max_lun <= 8))
         return 1;
     if (bflags & BLIST_NOLUN)
         return 0;
     if (starget->no_report_luns)
         return 1;
 
     if (!(sdev = scsi_device_lookup_by_target(starget, 0))) {
         sdev = scsi_alloc_sdev(starget, 0, NULL);
         if (!sdev)
             return 0;
         if (scsi_device_get(sdev)) {
             __scsi_remove_device(sdev);
             return 0;
         }
     }
 
     /*
      * Allocate enough to hold the header (the same size as one scsi_lun)
      * plus the number of luns we are requesting.  511 was the default
      * value of the now removed max_report_luns parameter.
      */
     length = (511 + 1) * sizeof(struct scsi_lun);
 retry:
     lun_data = kmalloc(length, GFP_KERNEL);
     if (!lun_data) {
         printk(ALLOC_FAILURE_MSG, __func__);
         goto out;
     }
 
     scsi_cmd[0] = REPORT_LUNS;
 
     /*
      * bytes 1 - 5: reserved, set to zero.
      */
     memset(&scsi_cmd[1], 0, 5);
 
     /*
      * bytes 6 - 9: length of the command.
      */
     put_unaligned_be32(length, &scsi_cmd[6]);
 
     scsi_cmd[10] = 0;   /* reserved */
     scsi_cmd[11] = 0;   /* control */
 
     /*
      * We can get a UNIT ATTENTION, for example a power on/reset, so
      * retry a few times (like sd.c does for TEST UNIT READY).
      * Experience shows some combinations of adapter/devices get at
      * least two power on/resets.
      *
      * Illegal requests (for devices that do not support REPORT LUNS)
      * should come through as a check condition, and will not generate
      * a retry.
      */
     for (retries = 0; retries < 3; retries++) {
         SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
                 "scsi scan: Sending REPORT LUNS to (try %d)\n",
                 retries));
 
         result = scsi_execute_req(sdev, scsi_cmd, DMA_FROM_DEVICE,
                       lun_data, length, &sshdr,
                       SCSI_REPORT_LUNS_TIMEOUT, 3, NULL);
 
         SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
                 "scsi scan: REPORT LUNS"
                 " %s (try %d) result 0x%x\n",
                 result ?  "failed" : "successful",
                 retries, result));
         if (result == 0)
             break;
         else if (scsi_sense_valid(&sshdr)) {
             if (sshdr.sense_key != UNIT_ATTENTION)
                 break;
         }
     }
 
     if (result) {
         /*
          * The device probably does not support a REPORT LUN command
          */
         ret = 1;
         goto out_err;
     }
 
     /*
      * Get the length from the first four bytes of lun_data.
      */
     if (get_unaligned_be32(lun_data->scsi_lun) +
         sizeof(struct scsi_lun) > length) {
         length = get_unaligned_be32(lun_data->scsi_lun) +
              sizeof(struct scsi_lun);
         kfree(lun_data);
         goto retry;
     }
     length = get_unaligned_be32(lun_data->scsi_lun);
 
     num_luns = (length / sizeof(struct scsi_lun));
 
     SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
         "scsi scan: REPORT LUN scan\n"));
 
     /*
      * Scan the luns in lun_data. The entry at offset 0 is really
      * the header, so start at 1 and go up to and including num_luns.
      */
     for (lunp = &lun_data[1]; lunp <= &lun_data[num_luns]; lunp++) {
         lun = scsilun_to_int(lunp);
 
         if (lun > sdev->host->max_lun) {
             sdev_printk(KERN_WARNING, sdev,
                     "lun%llu has a LUN larger than"
                     " allowed by the host adapter\n", lun);
         } else {
             int res;
 
             res = scsi_probe_and_add_lun(starget,
                 lun, NULL, NULL, rescan, NULL);
             if (res == SCSI_SCAN_NO_RESPONSE) {
                 /*
                  * Got some results, but now none, abort.
                  */
                 sdev_printk(KERN_ERR, sdev,
                     "Unexpected response"
                     " from lun %llu while scanning, scan"
                     " aborted\n", (unsigned long long)lun);
                 break;
             }
         }
     }
 
  out_err:
     kfree(lun_data);
  out:
     if (scsi_device_created(sdev))
         /*
          * the sdev we used didn't appear in the report luns scan
          */
         __scsi_remove_device(sdev);
     scsi_device_put(sdev);
     return ret;
 }
 
 struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
                       uint id, u64 lun, void *hostdata)
 {
     struct scsi_device *sdev = ERR_PTR(-ENODEV);
     struct device *parent = &shost->shost_gendev;
     struct scsi_target *starget;
 
     if (strncmp(scsi_scan_type, "none", 4) == 0)
         return ERR_PTR(-ENODEV);
 
     starget = scsi_alloc_target(parent, channel, id);
     if (!starget)
         return ERR_PTR(-ENOMEM);
     scsi_autopm_get_target(starget);
 
     mutex_lock(&shost->scan_mutex);
     if (!shost->async_scan)
         scsi_complete_async_scans();
 
     if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
         scsi_probe_and_add_lun(starget, lun, NULL, &sdev, 1, hostdata);
         scsi_autopm_put_host(shost);
     }
     mutex_unlock(&shost->scan_mutex);
     scsi_autopm_put_target(starget);
     /*
      * paired with scsi_alloc_target().  Target will be destroyed unless
      * scsi_probe_and_add_lun made an underlying device visible
      */
     scsi_target_reap(starget);
     put_device(&starget->dev);
 
     return sdev;
 }
 EXPORT_SYMBOL(__scsi_add_device);
 
 int scsi_add_device(struct Scsi_Host *host, uint channel,
             uint target, u64 lun)
 {
     struct scsi_device *sdev = 
         __scsi_add_device(host, channel, target, lun, NULL);
     if (IS_ERR(sdev))
         return PTR_ERR(sdev);
 
     scsi_device_put(sdev);
     return 0;
 }
 EXPORT_SYMBOL(scsi_add_device);
 
 void scsi_rescan_device(struct device *dev)
 {
     struct scsi_device *sdev = to_scsi_device(dev);
 
     device_lock(dev);
 
     scsi_attach_vpd(sdev);
 
     if (sdev->handler && sdev->handler->rescan)
         sdev->handler->rescan(sdev);
 
     if (dev->driver && try_module_get(dev->driver->owner)) {
         struct scsi_driver *drv = to_scsi_driver(dev->driver);
 
         if (drv->rescan)
             drv->rescan(dev);
         module_put(dev->driver->owner);
     }
     device_unlock(dev);
 }
 EXPORT_SYMBOL(scsi_rescan_device);
 
 static void __scsi_scan_target(struct device *parent, unsigned int channel,
         unsigned int id, u64 lun, enum scsi_scan_mode rescan)
 {
     struct Scsi_Host *shost = dev_to_shost(parent);
     blist_flags_t bflags = 0;
     int res;
     struct scsi_target *starget;
 
     if (shost->this_id == id)
         /*
          * Don't scan the host adapter
          */
         return;
 
     starget = scsi_alloc_target(parent, channel, id);
     if (!starget)
         return;
     scsi_autopm_get_target(starget);
 
     if (lun != SCAN_WILD_CARD) {
         /*
          * Scan for a specific host/chan/id/lun.
          */
         scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan, NULL);
         goto out_reap;
     }
 
     /*
      * Scan LUN 0, if there is some response, scan further. Ideally, we
      * would not configure LUN 0 until all LUNs are scanned.
      */
     res = scsi_probe_and_add_lun(starget, 0, &bflags, NULL, rescan, NULL);
     if (res == SCSI_SCAN_LUN_PRESENT || res == SCSI_SCAN_TARGET_PRESENT) {
         if (scsi_report_lun_scan(starget, bflags, rescan) != 0)
             /*
              * The REPORT LUN did not scan the target,
              * do a sequential scan.
              */
             scsi_sequential_lun_scan(starget, bflags,
                          starget->scsi_level, rescan);
     }
 
  out_reap:
     scsi_autopm_put_target(starget);
     /*
      * paired with scsi_alloc_target(): determine if the target has
      * any children at all and if not, nuke it
      */
     scsi_target_reap(starget);
 
     put_device(&starget->dev);
 }
 
 /**
  * scsi_scan_target - scan a target id, possibly including all LUNs on the target.
  * @parent: host to scan
  * @channel:    channel to scan
  * @id:     target id to scan
  * @lun:    Specific LUN to scan or SCAN_WILD_CARD
  * @rescan: passed to LUN scanning routines; SCSI_SCAN_INITIAL for
  *              no rescan, SCSI_SCAN_RESCAN to rescan existing LUNs,
  *              and SCSI_SCAN_MANUAL to force scanning even if
  *              'scan=manual' is set.
  *
  * Description:
  *     Scan the target id on @parent, @channel, and @id. Scan at least LUN 0,
  *     and possibly all LUNs on the target id.
  *
  *     First try a REPORT LUN scan, if that does not scan the target, do a
  *     sequential scan of LUNs on the target id.
  **/
 void scsi_scan_target(struct device *parent, unsigned int channel,
               unsigned int id, u64 lun, enum scsi_scan_mode rescan)
 {
     struct Scsi_Host *shost = dev_to_shost(parent);
 
     if (strncmp(scsi_scan_type, "none", 4) == 0)
         return;
 
     if (rescan != SCSI_SCAN_MANUAL &&
         strncmp(scsi_scan_type, "manual", 6) == 0)
         return;
 
     mutex_lock(&shost->scan_mutex);
     if (!shost->async_scan)
         scsi_complete_async_scans();
 
     if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
         __scsi_scan_target(parent, channel, id, lun, rescan);
         scsi_autopm_put_host(shost);
     }
     mutex_unlock(&shost->scan_mutex);
 }
 EXPORT_SYMBOL(scsi_scan_target);
 
 static void scsi_scan_channel(struct Scsi_Host *shost, unsigned int channel,
                   unsigned int id, u64 lun,
                   enum scsi_scan_mode rescan)
 {
     uint order_id;
 
     if (id == SCAN_WILD_CARD)
         for (id = 0; id < shost->max_id; ++id) {
             /*
              * XXX adapter drivers when possible (FCP, iSCSI)
              * could modify max_id to match the current max,
              * not the absolute max.
              *
              * XXX add a shost id iterator, so for example,
              * the FC ID can be the same as a target id
              * without a huge overhead of sparse id's.
              */
             if (shost->reverse_ordering)
                 /*
                  * Scan from high to low id.
                  */
                 order_id = shost->max_id - id - 1;
             else
                 order_id = id;
             __scsi_scan_target(&shost->shost_gendev, channel,
                     order_id, lun, rescan);
         }
     else
         __scsi_scan_target(&shost->shost_gendev, channel,
                 id, lun, rescan);
 }
 
 int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel,
                 unsigned int id, u64 lun,
                 enum scsi_scan_mode rescan)
 {
     SCSI_LOG_SCAN_BUS(3, shost_printk (KERN_INFO, shost,
         "%s: <%u:%u:%llu>\n",
         __func__, channel, id, lun));
 
     if (((channel != SCAN_WILD_CARD) && (channel > shost->max_channel)) ||
         ((id != SCAN_WILD_CARD) && (id >= shost->max_id)) ||
         ((lun != SCAN_WILD_CARD) && (lun >= shost->max_lun)))
         return -EINVAL;
 
     mutex_lock(&shost->scan_mutex);
     if (!shost->async_scan)
         scsi_complete_async_scans();
 
     if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
         if (channel == SCAN_WILD_CARD)
             for (channel = 0; channel <= shost->max_channel;
                  channel++)
                 scsi_scan_channel(shost, channel, id, lun,
                           rescan);
         else
             scsi_scan_channel(shost, channel, id, lun, rescan);
         scsi_autopm_put_host(shost);
     }
     mutex_unlock(&shost->scan_mutex);
 
     return 0;
 }
 
 static void scsi_sysfs_add_devices(struct Scsi_Host *shost)
 {
     struct scsi_device *sdev;
     shost_for_each_device(sdev, shost) {
         /* target removed before the device could be added */
         if (sdev->sdev_state == SDEV_DEL)
             continue;
         /* If device is already visible, skip adding it to sysfs */
         if (sdev->is_visible)
             continue;
         if (!scsi_host_scan_allowed(shost) ||
             scsi_sysfs_add_sdev(sdev) != 0)
             __scsi_remove_device(sdev);
     }
 }
 
 /**
  * scsi_prep_async_scan - prepare for an async scan
  * @shost: the host which will be scanned
  * Returns: a cookie to be passed to scsi_finish_async_scan()
  *
  * Tells the midlayer this host is going to do an asynchronous scan.
  * It reserves the host's position in the scanning list and ensures
  * that other asynchronous scans started after this one won't affect the
  * ordering of the discovered devices.
  */
 static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost)
 {
     struct async_scan_data *data = NULL;
     unsigned long flags;
 
     if (strncmp(scsi_scan_type, "sync", 4) == 0)
         return NULL;
 
     mutex_lock(&shost->scan_mutex);
     if (shost->async_scan) {
         shost_printk(KERN_DEBUG, shost, "%s called twice\n", __func__);
         goto err;
     }
 
     data = kmalloc(sizeof(*data), GFP_KERNEL);
     if (!data)
         goto err;
     data->shost = scsi_host_get(shost);
     if (!data->shost)
         goto err;
     init_completion(&data->prev_finished);
 
     spin_lock_irqsave(shost->host_lock, flags);
     shost->async_scan = 1;
     spin_unlock_irqrestore(shost->host_lock, flags);
     mutex_unlock(&shost->scan_mutex);
 
     spin_lock(&async_scan_lock);
     if (list_empty(&scanning_hosts))
         complete(&data->prev_finished);
     list_add_tail(&data->list, &scanning_hosts);
     spin_unlock(&async_scan_lock);
 
     return data;
 
  err:
     mutex_unlock(&shost->scan_mutex);
     kfree(data);
     return NULL;
 }
 
 /**
  * scsi_finish_async_scan - asynchronous scan has finished
  * @data: cookie returned from earlier call to scsi_prep_async_scan()
  *
  * All the devices currently attached to this host have been found.
  * This function announces all the devices it has found to the rest
  * of the system.
  */
 static void scsi_finish_async_scan(struct async_scan_data *data)
 {
     struct Scsi_Host *shost;
     unsigned long flags;
 
     if (!data)
         return;
 
     shost = data->shost;
 
     mutex_lock(&shost->scan_mutex);
 
     if (!shost->async_scan) {
         shost_printk(KERN_INFO, shost, "%s called twice\n", __func__);
         dump_stack();
         mutex_unlock(&shost->scan_mutex);
         return;
     }
 
     wait_for_completion(&data->prev_finished);
 
     scsi_sysfs_add_devices(shost);
 
     spin_lock_irqsave(shost->host_lock, flags);
     shost->async_scan = 0;
     spin_unlock_irqrestore(shost->host_lock, flags);
 
     mutex_unlock(&shost->scan_mutex);
 
     spin_lock(&async_scan_lock);
     list_del(&data->list);
     if (!list_empty(&scanning_hosts)) {
         struct async_scan_data *next = list_entry(scanning_hosts.next,
                 struct async_scan_data, list);
         complete(&next->prev_finished);
     }
     spin_unlock(&async_scan_lock);
 
     scsi_autopm_put_host(shost);
     scsi_host_put(shost);
     kfree(data);
 }
 
 static void do_scsi_scan_host(struct Scsi_Host *shost)
 {
     if (shost->hostt->scan_finished) {
         unsigned long start = jiffies;
         if (shost->hostt->scan_start)
             shost->hostt->scan_start(shost);
 
         while (!shost->hostt->scan_finished(shost, jiffies - start))
             msleep(10);
     } else {
         scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD,
                 SCAN_WILD_CARD, 0);
     }
 }
 
 static void do_scan_async(void *_data, async_cookie_t c)
 {
     struct async_scan_data *data = _data;
     struct Scsi_Host *shost = data->shost;
 
     do_scsi_scan_host(shost);
     scsi_finish_async_scan(data);
 }
 
 /**
  * scsi_scan_host - scan the given adapter
  * @shost:  adapter to scan
  **/
 void scsi_scan_host(struct Scsi_Host *shost)
 {
     struct async_scan_data *data;
 
     if (strncmp(scsi_scan_type, "none", 4) == 0 ||
         strncmp(scsi_scan_type, "manual", 6) == 0)
         return;
     if (scsi_autopm_get_host(shost) < 0)
         return;
 
     data = scsi_prep_async_scan(shost);
     if (!data) {
         do_scsi_scan_host(shost);
         scsi_autopm_put_host(shost);
         return;
     }
 
     /* register with the async subsystem so wait_for_device_probe()
      * will flush this work
      */
     async_schedule(do_scan_async, data);
 
     /* scsi_autopm_put_host(shost) is called in scsi_finish_async_scan() */
 }
 EXPORT_SYMBOL(scsi_scan_host);
 
 void scsi_forget_host(struct Scsi_Host *shost)
 {
     struct scsi_device *sdev;
     unsigned long flags;
 
  restart:
     spin_lock_irqsave(shost->host_lock, flags);
     list_for_each_entry(sdev, &shost->__devices, siblings) {
         if (sdev->sdev_state == SDEV_DEL)
             continue;
         spin_unlock_irqrestore(shost->host_lock, flags);
         __scsi_remove_device(sdev);
         goto restart;
     }
     spin_unlock_irqrestore(shost->host_lock, flags);
 }
 

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