scsi_scan.c

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/*
 * 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 <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 + 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;
};

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;
}

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, NULL);
}

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);
    extern void scsi_requeue_run_queue(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->queue_ramp_up_period = SCSI_DEFAULT_RAMP_UP_PERIOD;
    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);
    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->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;
    }
    WARN_ON_ONCE(!blk_get_queue(sdev->request_queue));
    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:
    __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;

    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;
}

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", __func__);
        return NULL;
    }
    dev = &starget->dev;
    device_initialize(dev);
    starget->reap_ref = 1;
    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;
    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) {
            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 */
            scsi_target_destroy(starget);
            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(dev);
        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);

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

void scsi_target_reap(struct scsi_target *starget)
{
    struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
    unsigned long flags;
    enum scsi_target_state state;
    int empty = 0;

    spin_lock_irqsave(shost->host_lock, flags);
    state = starget->state;
    if (--starget->reap_ref == 0 && list_empty(&starget->devices)) {
        empty = 1;
        starget->state = STARGET_DEL;
    }
    spin_unlock_irqrestore(shost->host_lock, flags);

    if (!empty)
        return;

    BUG_ON(state == STARGET_DEL);
    if (state == STARGET_CREATED)
        scsi_target_destroy(starget);
    else
        execute_in_process_context(scsi_target_reap_usercontext,
                       &starget->ew);
}

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 = ' ';
    }
}

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) {
        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, 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;
            }
        } else {
            /*
             * 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) {
        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;
}

static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
        int *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_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 (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;
    }

    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:
    case TYPE_OSD:
        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_hw_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)
        scsi_target(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 */
    ret = scsi_device_set_state(sdev, SDEV_RUNNING);
    if (ret) {
        ret = scsi_device_set_state(sdev, SDEV_BLOCK);

        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_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;

    if (*bflags & BLIST_NO_DIF)
        sdev->no_dif = 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;
        }
    }

    sdev->max_queue_depth = sdev->queue_depth;

    /*
     * 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

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

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 || !scsi_device_created(sdev)) {
            SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO
                "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_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_is_wlun(lun)) {
        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_remove_device(sdev);
 out:
    return res;
}

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", dev_name(&starget->dev)));

    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;
}

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);

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);

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.
     * 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;
        }
    }

    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, __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.
     */
    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, NULL);

        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 (scsi_device_created(sdev))
        /*
         * the sdev we used didn't appear in the report luns scan
         */
        __scsi_remove_device(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);
    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);
    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;
    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);
    /* now determine if the target has any children at all
     * and if not, nuke it */
    scsi_target_reap(starget);

    put_device(&starget->dev);
}

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_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, 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",
        __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 (!scsi_host_scan_allowed(shost) ||
            scsi_sysfs_add_sdev(sdev) != 0)
            __scsi_remove_device(sdev);
    }
}

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", __func__,
                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;
}

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", __func__,
                shost->host_no);
        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);
}

void scsi_scan_host(struct Scsi_Host *shost)
{
    struct async_scan_data *data;

    if (strncmp(scsi_scan_type, "none", 4) == 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);
}

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->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);

void scsi_free_host_dev(struct scsi_device *sdev)
{
    BUG_ON(sdev->id != sdev->host->this_id);

    __scsi_remove_device(sdev);
}
EXPORT_SYMBOL(scsi_free_host_dev);