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scsi_scan.c

/*
 * 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 <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_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)

/*
 * 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

#ifdef CONFIG_SCSI_MULTI_LUN
static unsigned int max_scsi_luns = MAX_SCSI_LUNS;
#else
static unsigned int max_scsi_luns = 1;
#endif

module_param_named(max_luns, max_scsi_luns, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(max_luns,
             "last scsi LUN (should be between 1 and 2^32-1)");

#ifdef CONFIG_SCSI_SCAN_ASYNC
#define SCSI_SCAN_TYPE_DEFAULT "async"
#else
#define SCSI_SCAN_TYPE_DEFAULT "sync"
#endif

static char scsi_scan_type[6] = SCSI_SCAN_TYPE_DEFAULT;

module_param_string(scan, scsi_scan_type, sizeof(scsi_scan_type), S_IRUGO);
MODULE_PARM_DESC(scan, "sync, async or none");

/*
 * max_scsi_report_luns: the maximum number of LUNS that will be
 * returned from the REPORT LUNS command. 8 times this value must
 * be allocated. In theory this could be up to an 8 byte value, but
 * in practice, the maximum number of LUNs suppored by any device
 * is about 16k.
 */
static unsigned int max_scsi_report_luns = 511;

module_param_named(max_report_luns, max_scsi_report_luns, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(max_report_luns,
             "REPORT LUNS maximum number of LUNS received (should be"
             " between 1 and 16384)");

static unsigned int scsi_inq_timeout = SCSI_TIMEOUT/HZ+3;

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 5. Some non-compliant devices need more.");

/* 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_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;
}

/* Only exported for the benefit of scsi_wait_scan */
EXPORT_SYMBOL_GPL(scsi_complete_async_scans);

#ifndef MODULE
/*
 * For async scanning we need to wait for all the scans to complete before
 * trying to mount the root fs.  Otherwise non-modular drivers may not be ready
 * yet.
 */
late_initcall(scsi_complete_async_scans);
#endif

/**
 * 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];

      printk(KERN_NOTICE "scsi: 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);
}

/**
 * scsi_alloc_sdev - allocate and setup a scsi_Device
 *
 * 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,
                                 unsigned int lun, void *hostdata)
{
      struct scsi_device *sdev;
      int display_failure_msg = 1, ret;
      struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
      extern void scsi_evt_thread(struct work_struct *work);

      sdev = kzalloc(sizeof(*sdev) + shost->transportt->device_size,
                   GFP_ATOMIC);
      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->id = starget->id;
      sdev->lun = lun;
      sdev->channel = starget->channel;
      sdev->sdev_state = SDEV_CREATED;
      INIT_LIST_HEAD(&sdev->siblings);
      INIT_LIST_HEAD(&sdev->same_target_siblings);
      INIT_LIST_HEAD(&sdev->cmd_list);
      INIT_LIST_HEAD(&sdev->starved_entry);
      INIT_LIST_HEAD(&sdev->event_list);
      spin_lock_init(&sdev->list_lock);
      INIT_WORK(&sdev->event_work, scsi_evt_thread);

      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->request_queue = scsi_alloc_queue(sdev);
      if (!sdev->request_queue) {
            /* 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;
      }

      sdev->request_queue->queuedata = sdev;
      scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);

      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:
      transport_destroy_device(&sdev->sdev_gendev);
      put_device(&sdev->sdev_gendev);
out:
      if (display_failure_msg)
            printk(ALLOC_FAILURE_MSG, __FUNCTION__);
      return NULL;
}

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);
}

int scsi_is_target_device(const struct device *dev)
{
      return dev->release == scsi_target_dev_release;
}
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_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;

      starget = kzalloc(size, GFP_KERNEL);
      if (!starget) {
            printk(KERN_ERR "%s: allocation failure\n", __FUNCTION__);
            return NULL;
      }
      dev = &starget->dev;
      device_initialize(dev);
      starget->reap_ref = 1;
      dev->parent = get_device(parent);
      dev->release = scsi_target_dev_release;
      sprintf(dev->bus_id, "target%d:%d:%d",
            shost->host_no, channel, id);
      starget->id = id;
      starget->channel = channel;
      INIT_LIST_HEAD(&starget->siblings);
      INIT_LIST_HEAD(&starget->devices);
      starget->state = STARGET_RUNNING;
      starget->scsi_level = SCSI_2;
 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);
      error = device_add(dev);
      if (error) {
            dev_err(dev, "target device_add failed, error %d\n", error);
            spin_lock_irqsave(shost->host_lock, flags);
            list_del_init(&starget->siblings);
            spin_unlock_irqrestore(shost->host_lock, flags);
            transport_destroy_device(dev);
            put_device(parent);
            kfree(starget);
            return NULL;
      }
      transport_add_device(dev);
      if (shost->hostt->target_alloc) {
            error = shost->hostt->target_alloc(starget);

            if(error) {
                  dev_printk(KERN_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 */
                  get_device(dev);
                  scsi_target_reap(starget);
                  put_device(dev);
                  return NULL;
            }
      }
      get_device(dev);

      return starget;

 found:
      found_target->reap_ref++;
      spin_unlock_irqrestore(shost->host_lock, flags);
      if (found_target->state != STARGET_DEL) {
            put_device(parent);
            kfree(starget);
            return found_target;
      }
      /* Unfortunately, we found a dying target; need to
       * wait until it's dead before we can get a new one */
      put_device(&found_target->dev);
      flush_scheduled_work();
      goto retry;
}

static void scsi_target_reap_usercontext(struct work_struct *work)
{
      struct scsi_target *starget =
            container_of(work, struct scsi_target, ew.work);
      struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
      unsigned long flags;

      transport_remove_device(&starget->dev);
      device_del(&starget->dev);
      transport_destroy_device(&starget->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(&starget->dev);
}

/**
 * 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)
{
      struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
      unsigned long flags;

      spin_lock_irqsave(shost->host_lock, flags);

      if (--starget->reap_ref == 0 && list_empty(&starget->devices)) {
            BUG_ON(starget->state == STARGET_DEL);
            starget->state = STARGET_DEL;
            spin_unlock_irqrestore(shost->host_lock, flags);
            execute_in_process_context(scsi_target_reap_usercontext,
                                 &starget->ew);
            return;

      }
      spin_unlock_irqrestore(shost->host_lock, flags);

      return;
}

/**
 * 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.
 **/
static void 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 = ' ';
      }
}

/**
 * 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, int *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) {
            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);

            SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO "scsi scan: INQUIRY %s "
                        "with code 0x%x\n",
                        result ? "failed" : "successful", result));

            if (result) {
                  /*
                   * 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 ((driver_byte(result) & DRIVER_SENSE) &&
                      scsi_sense_valid(&sshdr)) {
                        if ((sshdr.sense_key == UNIT_ATTENTION) &&
                            ((sshdr.asc == 0x28) ||
                             (sshdr.asc == 0x29)) &&
                            (sshdr.ascq == 0))
                              continue;
                  }
            }
            break;
      }

      if (result == 0) {
            sanitize_inquiry_string(&inq_result[8], 8);
            sanitize_inquiry_string(&inq_result[16], 16);
            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;
                  else if (BLIST_INQUIRY_58 & *bflags)
                        next_inquiry_len = 58;
                  else if (sdev->inquiry_len)
                        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) {
            printk(KERN_INFO "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) {
            printk(KERN_INFO "scsi scan: INQUIRY result too short (%d),"
                        " using 36\n", sdev->inquiry_len);
            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;

      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,
            int *bflags, int async)
{
      /*
       * 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_ATOMIC);
      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 (*bflags & BLIST_ISROM) {
            sdev->type = TYPE_ROM;
            sdev->removable = 1;
      } else {
            sdev->type = (inq_result[0] & 0x1f);
            sdev->removable = (inq_result[1] & 0x80) >> 7;
      }

      switch (sdev->type) {
      case TYPE_RBC:
      case TYPE_TAPE:
      case TYPE_DISK:
      case TYPE_PRINTER:
      case TYPE_MOD:
      case TYPE_PROCESSOR:
      case TYPE_SCANNER:
      case TYPE_MEDIUM_CHANGER:
      case TYPE_ENCLOSURE:
      case TYPE_COMM:
      case TYPE_RAID:
            sdev->writeable = 1;
            break;
      case TYPE_ROM:
      case TYPE_WORM:
            sdev->writeable = 0;
            break;
      default:
            printk(KERN_INFO "scsi: unknown device type %d\n", sdev->type);
      }

      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;

      /*
       * 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_sectors(sdev->request_queue, 512);

      /*
       * 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)
            sdev->single_lun = 1;

      sdev->use_10_for_rw = 1;

      if (*bflags & BLIST_MS_SKIP_PAGE_08)
            sdev->skip_ms_page_8 = 1;

      if (*bflags & BLIST_MS_SKIP_PAGE_3F)
            sdev->skip_ms_page_3f = 1;

      if (*bflags & BLIST_USE_10_BYTE_MS)
            sdev->use_10_for_ms = 1;

      /* set the device running here so that slave configure
       * may do I/O */
      scsi_device_set_state(sdev, SDEV_RUNNING);

      if (*bflags & BLIST_MS_192_BYTES_FOR_3F)
            sdev->use_192_bytes_for_3f = 1;

      if (*bflags & BLIST_NOT_LOCKABLE)
            sdev->lockable = 0;

      if (*bflags & BLIST_RETRY_HWERROR)
            sdev->retry_hwerror = 1;

      transport_configure_device(&sdev->sdev_gendev);

      if (sdev->host->hostt->slave_configure) {
            int 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;
            }
      }

      /*
       * 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;
}

static inline void scsi_destroy_sdev(struct scsi_device *sdev)
{
      scsi_device_set_state(sdev, SDEV_DEL);
      if (sdev->host->hostt->slave_destroy)
            sdev->host->hostt->slave_destroy(sdev);
      transport_destroy_device(&sdev->sdev_gendev);
      put_device(&sdev->sdev_gendev);
}

#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
 * @sdevscan:     probe the LUN corresponding to this scsi_device
 * @sdevnew:      store the value of any new scsi_device allocated
 * @bflagsp:      store bflags here if not NULL
 *
 * 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,
                          uint lun, int *bflagsp,
                          struct scsi_device **sdevp, int rescan,
                          void *hostdata)
{
      struct scsi_device *sdev;
      unsigned char *result;
      int bflags, 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 || sdev->sdev_state != SDEV_CREATED) {
                  SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO
                        "scsi scan: device exists on %s\n",
                        sdev->sdev_gendev.bus_id));
                  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_ATOMIC |
                  ((shost->unchecked_isa_dma) ? __GFP_DMA : 0));
      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) && !(bflags & BLIST_ATTACH_PQ3)) {
            /*
             * 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) 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_LOG_SCAN_BUS(3, printk(KERN_INFO
                              "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_destroy_sdev(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
 *
 * 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,
                             int bflags, int scsi_level, int rescan)
{
      unsigned int sparse_lun, lun, max_dev_lun;
      struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);

      SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO "scsi scan: Sequential scan of"
                            "%s\n", starget->dev.bus_id));

      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_CSS, and no special lun scaning, stop
       * scanning; this matches 2.4 behaviour, but could just be a bug
       * (to continue scanning a SCSI_1_CSS 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);

      /*
       * 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;
}

/**
 * scsilun_to_int: convert a scsi_lun to an int
 * @scsilun:      struct scsi_lun to be converted.
 *
 * Description:
 *     Convert @scsilun from a struct scsi_lun to a four byte host byte-ordered
 *     integer, and return the result. The caller must check for
 *     truncation before using this function.
 *
 * Notes:
 *     The struct scsi_lun is assumed to be four levels, with each level
 *     effectively containing a SCSI byte-ordered (big endian) short; the
 *     addressing bits of each level are ignored (the highest two bits).
 *     For a description of the LUN format, post SCSI-3 see the SCSI
 *     Architecture Model, for SCSI-3 see the SCSI Controller Commands.
 *
 *     Given a struct scsi_lun of: 0a 04 0b 03 00 00 00 00, this function returns
 *     the integer: 0x0b030a04
 **/
int scsilun_to_int(struct scsi_lun *scsilun)
{
      int i;
      unsigned int lun;

      lun = 0;
      for (i = 0; i < sizeof(lun); i += 2)
            lun = lun | (((scsilun->scsi_lun[i] << 8) |
                        scsilun->scsi_lun[i + 1]) << (i * 8));
      return lun;
}
EXPORT_SYMBOL(scsilun_to_int);

/**
 * int_to_scsilun: reverts an int into a scsi_lun
 * @int:        integer to be reverted
 * @scsilun:      struct scsi_lun to be set.
 *
 * Description:
 *     Reverts the functionality of the scsilun_to_int, which packed
 *     an 8-byte lun value into an int. This routine unpacks the int
 *     back into the lun value.
 *     Note: the scsilun_to_int() routine does not truly handle all
 *     8bytes of the lun value. This functions restores only as much
 *     as was set by the routine.
 *
 * Notes:
 *     Given an integer : 0x0b030a04,  this function returns a
 *     scsi_lun of : struct scsi_lun of: 0a 04 0b 03 00 00 00 00
 *
 **/
void int_to_scsilun(unsigned int lun, struct scsi_lun *scsilun)
{
      int i;

      memset(scsilun->scsi_lun, 0, sizeof(scsilun->scsi_lun));

      for (i = 0; i < sizeof(lun); i += 2) {
            scsilun->scsi_lun[i] = (lun >> 8) & 0xFF;
            scsilun->scsi_lun[i+1] = lun & 0xFF;
            lun = lun >> 16;
      }
}
EXPORT_SYMBOL(int_to_scsilun);

/**
 * scsi_report_lun_scan - Scan using SCSI REPORT LUN results
 * @sdevscan:     scan the host, channel, and id of this scsi_device
 *
 * Description:
 *     If @sdevscan is for a SCSI-3 or up device, send a REPORT LUN
 *     command, and scan the resulting list of LUNs by calling
 *     scsi_probe_and_add_lun.
 *
 *     Modifies sdevscan->lun.
 *
 * Return:
 *     0: scan completed (or no memory, so further scanning is futile)
 *     1: no report lun scan, or not configured
 **/
static int scsi_report_lun_scan(struct scsi_target *starget, int bflags,
                        int rescan)
{
      char devname[64];
      unsigned char scsi_cmd[MAX_COMMAND_SIZE];
      unsigned int length;
      unsigned int lun;
      unsigned int num_luns;
      unsigned int retries;
      int result;
      struct scsi_lun *lunp, *lun_data;
      u8 *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.
       */
      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 (!(sdev = scsi_device_lookup_by_target(starget, 0))) {
            sdev = scsi_alloc_sdev(starget, 0, NULL);
            if (!sdev)
                  return 0;
            if (scsi_device_get(sdev))
                  return 0;
      }

      sprintf(devname, "host %d channel %d id %d",
            shost->host_no, sdev->channel, sdev->id);

      /*
       * Allocate enough to hold the header (the same size as one scsi_lun)
       * plus the max number of luns we are requesting.
       *
       * Reallocating and trying again (with the exact amount we need)
       * would be nice, but then we need to somehow limit the size
       * allocated based on the available memory and the limits of
       * kmalloc - we don't want a kmalloc() failure of a huge value to
       * prevent us from finding any LUNs on this target.
       */
      length = (max_scsi_report_luns + 1) * sizeof(struct scsi_lun);
      lun_data = kmalloc(length, GFP_ATOMIC |
                     (sdev->host->unchecked_isa_dma ? __GFP_DMA : 0));
      if (!lun_data) {
            printk(ALLOC_FAILURE_MSG, __FUNCTION__);
            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.
       */
      scsi_cmd[6] = (unsigned char) (length >> 24) & 0xff;
      scsi_cmd[7] = (unsigned char) (length >> 16) & 0xff;
      scsi_cmd[8] = (unsigned char) (length >> 8) & 0xff;
      scsi_cmd[9] = (unsigned char) length & 0xff;

      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, printk (KERN_INFO "scsi scan: Sending"
                        " REPORT LUNS to %s (try %d)\n", devname,
                        retries));

            result = scsi_execute_req(sdev, scsi_cmd, DMA_FROM_DEVICE,
                                lun_data, length, &sshdr,
                                SCSI_TIMEOUT + 4 * HZ, 3);

            SCSI_LOG_SCAN_BUS(3, printk (KERN_INFO "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.
       */
      data = (u8 *) lun_data->scsi_lun;
      length = ((data[0] << 24) | (data[1] << 16) |
              (data[2] << 8) | (data[3] << 0));

      num_luns = (length / sizeof(struct scsi_lun));
      if (num_luns > max_scsi_report_luns) {
            printk(KERN_WARNING "scsi: On %s only %d (max_scsi_report_luns)"
                   " of %d luns reported, try increasing"
                   " max_scsi_report_luns.\n", devname,
                   max_scsi_report_luns, num_luns);
            num_luns = max_scsi_report_luns;
      }

      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);

            /*
             * Check if the unused part of lunp is non-zero, and so
             * does not fit in lun.
             */
            if (memcmp(&lunp->scsi_lun[sizeof(lun)], "\0\0\0\0", 4)) {
                  int i;

                  /*
                   * Output an error displaying the LUN in byte order,
                   * this differs from what linux would print for the
                   * integer LUN value.
                   */
                  printk(KERN_WARNING "scsi: %s lun 0x", devname);
                  data = (char *)lunp->scsi_lun;
                  for (i = 0; i < sizeof(struct scsi_lun); i++)
                        printk("%02x", data[i]);
                  printk(" has a LUN larger than currently supported.\n");
            } else if (lun > sdev->host->max_lun) {
                  printk(KERN_WARNING "scsi: %s lun%d has a LUN larger"
                         " than allowed by the host adapter\n",
                         devname, 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 %d while scanning, scan"
                                " aborted\n", lun);
                        break;
                  }
            }
      }

 out_err:
      kfree(lun_data);
 out:
      scsi_device_put(sdev);
      if (sdev->sdev_state == SDEV_CREATED)
            /*
             * the sdev we used didn't appear in the report luns scan
             */
            scsi_destroy_sdev(sdev);
      return ret;
}

struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
                              uint id, uint 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);

      mutex_lock(&shost->scan_mutex);
      if (!shost->async_scan)
            scsi_complete_async_scans();

      if (scsi_host_scan_allowed(shost))
            scsi_probe_and_add_lun(starget, lun, NULL, &sdev, 1, hostdata);
      mutex_unlock(&shost->scan_mutex);
      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, uint 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_driver *drv;
      
      if (!dev->driver)
            return;

      drv = to_scsi_driver(dev->driver);
      if (try_module_get(drv->owner)) {
            if (drv->rescan)
                  drv->rescan(dev);
            module_put(drv->owner);
      }
}
EXPORT_SYMBOL(scsi_rescan_device);

static void __scsi_scan_target(struct device *parent, unsigned int channel,
            unsigned int id, unsigned int lun, int rescan)
{
      struct Scsi_Host *shost = dev_to_shost(parent);
      int 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;

      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:
      /* now 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
 *
 * 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, unsigned int lun, int rescan)
{
      struct Scsi_Host *shost = dev_to_shost(parent);

      if (strncmp(scsi_scan_type, "none", 4) == 0)
            return;

      mutex_lock(&shost->scan_mutex);
      if (!shost->async_scan)
            scsi_complete_async_scans();

      if (scsi_host_scan_allowed(shost))
            __scsi_scan_target(parent, channel, id, lun, rescan);
      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, unsigned int lun, int 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, unsigned int lun, int rescan)
{
      SCSI_LOG_SCAN_BUS(3, shost_printk (KERN_INFO, shost,
            "%s: <%u:%u:%u>\n",
            __FUNCTION__, 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)) {
            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);
      }
      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) {
            if (!scsi_host_scan_allowed(shost) ||
                scsi_sysfs_add_sdev(sdev) != 0)
                  scsi_destroy_sdev(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;
      unsigned long flags;

      if (strncmp(scsi_scan_type, "sync", 4) == 0)
            return NULL;

      if (shost->async_scan) {
            printk("%s called twice for host %d", __FUNCTION__,
                        shost->host_no);
            dump_stack();
            return NULL;
      }

      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);

      mutex_lock(&shost->scan_mutex);
      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:
      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) {
            printk("%s called twice for host %d", __FUNCTION__,
                        shost->host_no);
            dump_stack();
            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_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 int do_scan_async(void *_data)
{
      struct async_scan_data *data = _data;
      do_scsi_scan_host(data->shost);
      scsi_finish_async_scan(data);
      return 0;
}

/**
 * scsi_scan_host - scan the given adapter
 * @shost:  adapter to scan
 **/
void scsi_scan_host(struct Scsi_Host *shost)
{
      struct task_struct *p;
      struct async_scan_data *data;

      if (strncmp(scsi_scan_type, "none", 4) == 0)
            return;

      data = scsi_prep_async_scan(shost);
      if (!data) {
            do_scsi_scan_host(shost);
            return;
      }

      p = kthread_run(do_scan_async, data, "scsi_scan_%d", shost->host_no);
      if (unlikely(IS_ERR(p)))
            do_scan_async(data);
}
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);
}

/*
 * Function:    scsi_get_host_dev()
 *
 * Purpose:     Create a scsi_device that points to the host adapter itself.
 *
 * Arguments:   SHpnt   - Host that needs a scsi_device
 *
 * Lock status: None assumed.
 *
 * Returns:     The scsi_device or NULL
 *
 * Notes:
 *    Attach a single scsi_device to the Scsi_Host - this should
 *    be made to look like a "pseudo-device" that points to the
 *    HA itself.
 *
 *    Note - this device is not accessible from any high-level
 *    drivers (including generics), which is probably not
 *    optimal.  We can add hooks later to attach 
 */
struct scsi_device *scsi_get_host_dev(struct Scsi_Host *shost)
{
      struct scsi_device *sdev = NULL;
      struct scsi_target *starget;

      mutex_lock(&shost->scan_mutex);
      if (!scsi_host_scan_allowed(shost))
            goto out;
      starget = scsi_alloc_target(&shost->shost_gendev, 0, shost->this_id);
      if (!starget)
            goto out;

      sdev = scsi_alloc_sdev(starget, 0, NULL);
      if (sdev) {
            sdev->sdev_gendev.parent = get_device(&starget->dev);
            sdev->borken = 0;
      } else
            scsi_target_reap(starget);
      put_device(&starget->dev);
 out:
      mutex_unlock(&shost->scan_mutex);
      return sdev;
}
EXPORT_SYMBOL(scsi_get_host_dev);

/*
 * Function:    scsi_free_host_dev()
 *
 * Purpose:     Free a scsi_device that points to the host adapter itself.
 *
 * Arguments:   SHpnt   - Host that needs a scsi_device
 *
 * Lock status: None assumed.
 *
 * Returns:     Nothing
 *
 * Notes:
 */
void scsi_free_host_dev(struct scsi_device *sdev)
{
      BUG_ON(sdev->id != sdev->host->this_id);

      scsi_destroy_sdev(sdev);
}
EXPORT_SYMBOL(scsi_free_host_dev);


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