// SPDX-License-Identifier: GPL-2.0
/*
 * scsi_sysfs.c
 *
 * SCSI sysfs interface routines.
 *
 * Created to pull SCSI mid layer sysfs routines into one file.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/device.h>
#include <linux/pm_runtime.h>

#include <scsi/scsi.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_dh.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_devinfo.h>

#include "scsi_priv.h"
#include "scsi_logging.h"

static struct device_type scsi_dev_type;

static const struct {
        enum scsi_device_state  value;
        char                    *name;
} sdev_states[] = {
        { SDEV_CREATED, "created" },
        { SDEV_RUNNING, "running" },
        { SDEV_CANCEL, "cancel" },
        { SDEV_DEL, "deleted" },
        { SDEV_QUIESCE, "quiesce" },
        { SDEV_OFFLINE, "offline" },
        { SDEV_TRANSPORT_OFFLINE, "transport-offline" },
        { SDEV_BLOCK,   "blocked" },
        { SDEV_CREATED_BLOCK, "created-blocked" },
};

const char *scsi_device_state_name(enum scsi_device_state state)
{
        int i;
        char *name = NULL;

        for (i = 0; i < ARRAY_SIZE(sdev_states); i++) {
                if (sdev_states[i].value == state) {
                        name = sdev_states[i].name;
                        break;
                }
        }
        return name;
}

static const struct {
        enum scsi_host_state    value;
        char                    *name;
} shost_states[] = {
        { SHOST_CREATED, "created" },
        { SHOST_RUNNING, "running" },
        { SHOST_CANCEL, "cancel" },
        { SHOST_DEL, "deleted" },
        { SHOST_RECOVERY, "recovery" },
        { SHOST_CANCEL_RECOVERY, "cancel/recovery" },
        { SHOST_DEL_RECOVERY, "deleted/recovery", },
};
const char *scsi_host_state_name(enum scsi_host_state state)
{
        int i;
        char *name = NULL;

        for (i = 0; i < ARRAY_SIZE(shost_states); i++) {
                if (shost_states[i].value == state) {
                        name = shost_states[i].name;
                        break;
                }
        }
        return name;
}

#ifdef CONFIG_SCSI_DH
static const struct {
        unsigned char   value;
        char            *name;
} sdev_access_states[] = {
        { SCSI_ACCESS_STATE_OPTIMAL, "active/optimized" },
        { SCSI_ACCESS_STATE_ACTIVE, "active/non-optimized" },
        { SCSI_ACCESS_STATE_STANDBY, "standby" },
        { SCSI_ACCESS_STATE_UNAVAILABLE, "unavailable" },
        { SCSI_ACCESS_STATE_LBA, "lba-dependent" },
        { SCSI_ACCESS_STATE_OFFLINE, "offline" },
        { SCSI_ACCESS_STATE_TRANSITIONING, "transitioning" },
};

static const char *scsi_access_state_name(unsigned char state)
{
        int i;
        char *name = NULL;

        for (i = 0; i < ARRAY_SIZE(sdev_access_states); i++) {
                if (sdev_access_states[i].value == state) {
                        name = sdev_access_states[i].name;
                        break;
                }
        }
        return name;
}
#endif

static int check_set(unsigned long long *val, char *src)
{
        char *last;

        if (strcmp(src, "-") == 0) {
                *val = SCAN_WILD_CARD;
        } else {
                /*
                 * Doesn't check for int overflow
                 */
                *val = simple_strtoull(src, &last, 0);
                if (*last != '\0')
                        return 1;
        }
        return 0;
}

static int scsi_scan(struct Scsi_Host *shost, const char *str)
{
        char s1[15], s2[15], s3[17], junk;
        unsigned long long channel, id, lun;
        int res;

        res = sscanf(str, "%10s %10s %16s %c", s1, s2, s3, &junk);
        if (res != 3)
                return -EINVAL;
        if (check_set(&channel, s1))
                return -EINVAL;
        if (check_set(&id, s2))
                return -EINVAL;
        if (check_set(&lun, s3))
                return -EINVAL;
        if (shost->transportt->user_scan)
                res = shost->transportt->user_scan(shost, channel, id, lun);
        else
                res = scsi_scan_host_selected(shost, channel, id, lun,
                                              SCSI_SCAN_MANUAL);
        return res;
}

/*
 * shost_show_function: macro to create an attr function that can be used to
 * show a non-bit field.
 */
#define shost_show_function(name, field, format_string)                 \
static ssize_t                                                          \
show_##name (struct device *dev, struct device_attribute *attr,         \
             char *buf)                                                 \
{                                                                       \
        struct Scsi_Host *shost = class_to_shost(dev);                  \
        return snprintf (buf, 20, format_string, shost->field);         \
}

/*
 * shost_rd_attr: macro to create a function and attribute variable for a
 * read only field.
 */
#define shost_rd_attr2(name, field, format_string)                      \
        shost_show_function(name, field, format_string)                 \
static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL);

#define shost_rd_attr(field, format_string) \
shost_rd_attr2(field, field, format_string)

/*
 * Create the actual show/store functions and data structures.
 */

static ssize_t
store_scan(struct device *dev, struct device_attribute *attr,
           const char *buf, size_t count)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        int res;

        res = scsi_scan(shost, buf);
        if (res == 0)
                res = count;
        return res;
};
static DEVICE_ATTR(scan, S_IWUSR, NULL, store_scan);

static ssize_t
store_shost_state(struct device *dev, struct device_attribute *attr,
                  const char *buf, size_t count)
{
        int i;
        struct Scsi_Host *shost = class_to_shost(dev);
        enum scsi_host_state state = 0;

        for (i = 0; i < ARRAY_SIZE(shost_states); i++) {
                const int len = strlen(shost_states[i].name);
                if (strncmp(shost_states[i].name, buf, len) == 0 &&
                   buf[len] == '\n') {
                        state = shost_states[i].value;
                        break;
                }
        }
        if (!state)
                return -EINVAL;

        if (scsi_host_set_state(shost, state))
                return -EINVAL;
        return count;
}

static ssize_t
show_shost_state(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        const char *name = scsi_host_state_name(shost->shost_state);

        if (!name)
                return -EINVAL;

        return snprintf(buf, 20, "%s\n", name);
}

/* DEVICE_ATTR(state) clashes with dev_attr_state for sdev */
static struct device_attribute dev_attr_hstate =
        __ATTR(state, S_IRUGO | S_IWUSR, show_shost_state, store_shost_state);

static ssize_t
show_shost_mode(unsigned int mode, char *buf)
{
        ssize_t len = 0;

        if (mode & MODE_INITIATOR)
                len = sprintf(buf, "%s", "Initiator");

        if (mode & MODE_TARGET)
                len += sprintf(buf + len, "%s%s", len ? ", " : "", "Target");

        len += sprintf(buf + len, "\n");

        return len;
}

static ssize_t
show_shost_supported_mode(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        unsigned int supported_mode = shost->hostt->supported_mode;

        if (supported_mode == MODE_UNKNOWN)
                /* by default this should be initiator */
                supported_mode = MODE_INITIATOR;

        return show_shost_mode(supported_mode, buf);
}

static DEVICE_ATTR(supported_mode, S_IRUGO | S_IWUSR, show_shost_supported_mode, NULL);

static ssize_t
show_shost_active_mode(struct device *dev,
                       struct device_attribute *attr, char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);

        if (shost->active_mode == MODE_UNKNOWN)
                return snprintf(buf, 20, "unknown\n");
        else
                return show_shost_mode(shost->active_mode, buf);
}

static DEVICE_ATTR(active_mode, S_IRUGO | S_IWUSR, show_shost_active_mode, NULL);

static int check_reset_type(const char *str)
{
        if (sysfs_streq(str, "adapter"))
                return SCSI_ADAPTER_RESET;
        else if (sysfs_streq(str, "firmware"))
                return SCSI_FIRMWARE_RESET;
        else
                return 0;
}

static ssize_t
store_host_reset(struct device *dev, struct device_attribute *attr,
                const char *buf, size_t count)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        struct scsi_host_template *sht = shost->hostt;
        int ret = -EINVAL;
        int type;

        type = check_reset_type(buf);
        if (!type)
                goto exit_store_host_reset;

        if (sht->host_reset)
                ret = sht->host_reset(shost, type);
        else
                ret = -EOPNOTSUPP;

exit_store_host_reset:
        if (ret == 0)
                ret = count;
        return ret;
}

static DEVICE_ATTR(host_reset, S_IWUSR, NULL, store_host_reset);

static ssize_t
show_shost_eh_deadline(struct device *dev,
                      struct device_attribute *attr, char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);

        if (shost->eh_deadline == -1)
                return snprintf(buf, strlen("off") + 2, "off\n");
        return sprintf(buf, "%u\n", shost->eh_deadline / HZ);
}

static ssize_t
store_shost_eh_deadline(struct device *dev, struct device_attribute *attr,
                const char *buf, size_t count)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        int ret = -EINVAL;
        unsigned long deadline, flags;

        if (shost->transportt &&
            (shost->transportt->eh_strategy_handler ||
             !shost->hostt->eh_host_reset_handler))
                return ret;

        if (!strncmp(buf, "off", strlen("off")))
                deadline = -1;
        else {
                ret = kstrtoul(buf, 10, &deadline);
                if (ret)
                        return ret;
                if (deadline * HZ > UINT_MAX)
                        return -EINVAL;
        }

        spin_lock_irqsave(shost->host_lock, flags);
        if (scsi_host_in_recovery(shost))
                ret = -EBUSY;
        else {
                if (deadline == -1)
                        shost->eh_deadline = -1;
                else
                        shost->eh_deadline = deadline * HZ;

                ret = count;
        }
        spin_unlock_irqrestore(shost->host_lock, flags);

        return ret;
}

static DEVICE_ATTR(eh_deadline, S_IRUGO | S_IWUSR, show_shost_eh_deadline, store_shost_eh_deadline);

shost_rd_attr(unique_id, "%u\n");
shost_rd_attr(cmd_per_lun, "%hd\n");
shost_rd_attr(can_queue, "%d\n");
shost_rd_attr(sg_tablesize, "%hu\n");
shost_rd_attr(sg_prot_tablesize, "%hu\n");
shost_rd_attr(unchecked_isa_dma, "%d\n");
shost_rd_attr(prot_capabilities, "%u\n");
shost_rd_attr(prot_guard_type, "%hd\n");
shost_rd_attr2(proc_name, hostt->proc_name, "%s\n");

static ssize_t
show_host_busy(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        return snprintf(buf, 20, "%d\n", scsi_host_busy(shost));
}
static DEVICE_ATTR(host_busy, S_IRUGO, show_host_busy, NULL);

static ssize_t
show_use_blk_mq(struct device *dev, struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "1\n");
}
static DEVICE_ATTR(use_blk_mq, S_IRUGO, show_use_blk_mq, NULL);

static ssize_t
show_nr_hw_queues(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        struct blk_mq_tag_set *tag_set = &shost->tag_set;

        return snprintf(buf, 20, "%d\n", tag_set->nr_hw_queues);
}
static DEVICE_ATTR(nr_hw_queues, S_IRUGO, show_nr_hw_queues, NULL);

static struct attribute *scsi_sysfs_shost_attrs[] = {
        &dev_attr_use_blk_mq.attr,
        &dev_attr_unique_id.attr,
        &dev_attr_host_busy.attr,
        &dev_attr_cmd_per_lun.attr,
        &dev_attr_can_queue.attr,
        &dev_attr_sg_tablesize.attr,
        &dev_attr_sg_prot_tablesize.attr,
        &dev_attr_unchecked_isa_dma.attr,
        &dev_attr_proc_name.attr,
        &dev_attr_scan.attr,
        &dev_attr_hstate.attr,
        &dev_attr_supported_mode.attr,
        &dev_attr_active_mode.attr,
        &dev_attr_prot_capabilities.attr,
        &dev_attr_prot_guard_type.attr,
        &dev_attr_host_reset.attr,
        &dev_attr_eh_deadline.attr,
        &dev_attr_nr_hw_queues.attr,
        NULL
};

static struct attribute_group scsi_shost_attr_group = {
        .attrs =        scsi_sysfs_shost_attrs,
};

const struct attribute_group *scsi_sysfs_shost_attr_groups[] = {
        &scsi_shost_attr_group,
        NULL
};

static void scsi_device_cls_release(struct device *class_dev)
{
        struct scsi_device *sdev;

        sdev = class_to_sdev(class_dev);
        put_device(&sdev->sdev_gendev);
}

static void scsi_device_dev_release_usercontext(struct work_struct *work)
{
        struct scsi_device *sdev;
        struct device *parent;
        struct list_head *this, *tmp;
        struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL;
        struct scsi_vpd *vpd_pg0 = NULL, *vpd_pg89 = NULL;
        unsigned long flags;
        struct module *mod;

        sdev = container_of(work, struct scsi_device, ew.work);

        mod = sdev->host->hostt->module;

        scsi_dh_release_device(sdev);

        parent = sdev->sdev_gendev.parent;

        spin_lock_irqsave(sdev->host->host_lock, flags);
        list_del(&sdev->siblings);
        list_del(&sdev->same_target_siblings);
        list_del(&sdev->starved_entry);
        spin_unlock_irqrestore(sdev->host->host_lock, flags);

        cancel_work_sync(&sdev->event_work);

        list_for_each_safe(this, tmp, &sdev->event_list) {
                struct scsi_event *evt;

                evt = list_entry(this, struct scsi_event, node);
                list_del(&evt->node);
                kfree(evt);
        }

        blk_put_queue(sdev->request_queue);
        /* NULL queue means the device can't be used */
        sdev->request_queue = NULL;

        sbitmap_free(sdev->budget_map);
        kfree(sdev->budget_map);

        mutex_lock(&sdev->inquiry_mutex);
        vpd_pg0 = rcu_replace_pointer(sdev->vpd_pg0, vpd_pg0,
                                       lockdep_is_held(&sdev->inquiry_mutex));
        vpd_pg80 = rcu_replace_pointer(sdev->vpd_pg80, vpd_pg80,
                                       lockdep_is_held(&sdev->inquiry_mutex));
        vpd_pg83 = rcu_replace_pointer(sdev->vpd_pg83, vpd_pg83,
                                       lockdep_is_held(&sdev->inquiry_mutex));
        vpd_pg89 = rcu_replace_pointer(sdev->vpd_pg89, vpd_pg89,
                                       lockdep_is_held(&sdev->inquiry_mutex));
        mutex_unlock(&sdev->inquiry_mutex);

        if (vpd_pg0)
                kfree_rcu(vpd_pg0, rcu);
        if (vpd_pg83)
                kfree_rcu(vpd_pg83, rcu);
        if (vpd_pg80)
                kfree_rcu(vpd_pg80, rcu);
        if (vpd_pg89)
                kfree_rcu(vpd_pg89, rcu);
        kfree(sdev->inquiry);
        kfree(sdev);

        if (parent)
                put_device(parent);
        module_put(mod);
}

static void scsi_device_dev_release(struct device *dev)
{
        struct scsi_device *sdp = to_scsi_device(dev);

        /* Set module pointer as NULL in case of module unloading */
        if (!try_module_get(sdp->host->hostt->module))
                sdp->host->hostt->module = NULL;

        execute_in_process_context(scsi_device_dev_release_usercontext,
                                   &sdp->ew);
}

static struct class sdev_class = {
        .name           = "scsi_device",
        .dev_release    = scsi_device_cls_release,
};

/* all probing is done in the individual ->probe routines */
static int scsi_bus_match(struct device *dev, struct device_driver *gendrv)
{
        struct scsi_device *sdp;

        if (dev->type != &scsi_dev_type)
                return 0;

        sdp = to_scsi_device(dev);
        if (sdp->no_uld_attach)
                return 0;
        return (sdp->inq_periph_qual == SCSI_INQ_PQ_CON)? 1: 0;
}

static int scsi_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        struct scsi_device *sdev;

        if (dev->type != &scsi_dev_type)
                return 0;

        sdev = to_scsi_device(dev);

        add_uevent_var(env, "MODALIAS=" SCSI_DEVICE_MODALIAS_FMT, sdev->type);
        return 0;
}

struct bus_type scsi_bus_type = {
        .name           = "scsi",
        .match          = scsi_bus_match,
        .uevent         = scsi_bus_uevent,
#ifdef CONFIG_PM
        .pm             = &scsi_bus_pm_ops,
#endif
};
EXPORT_SYMBOL_GPL(scsi_bus_type);

int scsi_sysfs_register(void)
{
        int error;

        error = bus_register(&scsi_bus_type);
        if (!error) {
                error = class_register(&sdev_class);
                if (error)
                        bus_unregister(&scsi_bus_type);
        }

        return error;
}

void scsi_sysfs_unregister(void)
{
        class_unregister(&sdev_class);
        bus_unregister(&scsi_bus_type);
}

/*
 * sdev_show_function: macro to create an attr function that can be used to
 * show a non-bit field.
 */
#define sdev_show_function(field, format_string)                                \
static ssize_t                                                          \
sdev_show_##field (struct device *dev, struct device_attribute *attr,   \
                   char *buf)                                           \
{                                                                       \
        struct scsi_device *sdev;                                       \
        sdev = to_scsi_device(dev);                                     \
        return snprintf (buf, 20, format_string, sdev->field);          \
}                                                                       \

/*
 * sdev_rd_attr: macro to create a function and attribute variable for a
 * read only field.
 */
#define sdev_rd_attr(field, format_string)                              \
        sdev_show_function(field, format_string)                        \
static DEVICE_ATTR(field, S_IRUGO, sdev_show_##field, NULL);


/*
 * sdev_rw_attr: create a function and attribute variable for a
 * read/write field.
 */
#define sdev_rw_attr(field, format_string)                              \
        sdev_show_function(field, format_string)                                \
                                                                        \
static ssize_t                                                          \
sdev_store_##field (struct device *dev, struct device_attribute *attr,  \
                    const char *buf, size_t count)                      \
{                                                                       \
        struct scsi_device *sdev;                                       \
        sdev = to_scsi_device(dev);                                     \
        sscanf (buf, format_string, &sdev->field);                      \
        return count;                                                   \
}                                                                       \
static DEVICE_ATTR(field, S_IRUGO | S_IWUSR, sdev_show_##field, sdev_store_##field);

/* Currently we don't export bit fields, but we might in future,
 * so leave this code in */
#if 0
/*
 * sdev_rd_attr: create a function and attribute variable for a
 * read/write bit field.
 */
#define sdev_rw_attr_bit(field)                                         \
        sdev_show_function(field, "%d\n")                                       \
                                                                        \
static ssize_t                                                          \
sdev_store_##field (struct device *dev, struct device_attribute *attr,  \
                    const char *buf, size_t count)                      \
{                                                                       \
        int ret;                                                        \
        struct scsi_device *sdev;                                       \
        ret = scsi_sdev_check_buf_bit(buf);                             \
        if (ret >= 0)   {                                               \
                sdev = to_scsi_device(dev);                             \
                sdev->field = ret;                                      \
                ret = count;                                            \
        }                                                               \
        return ret;                                                     \
}                                                                       \
static DEVICE_ATTR(field, S_IRUGO | S_IWUSR, sdev_show_##field, sdev_store_##field);

/*
 * scsi_sdev_check_buf_bit: return 0 if buf is "0", return 1 if buf is "1",
 * else return -EINVAL.
 */
static int scsi_sdev_check_buf_bit(const char *buf)
{
        if ((buf[1] == '\0') || ((buf[1] == '\n') && (buf[2] == '\0'))) {
                if (buf[0] == '1')
                        return 1;
                else if (buf[0] == '0')
                        return 0;
                else 
                        return -EINVAL;
        } else
                return -EINVAL;
}
#endif
/*
 * Create the actual show/store functions and data structures.
 */
sdev_rd_attr (type, "%d\n");
sdev_rd_attr (scsi_level, "%d\n");
sdev_rd_attr (vendor, "%.8s\n");
sdev_rd_attr (model, "%.16s\n");
sdev_rd_attr (rev, "%.4s\n");

static ssize_t
sdev_show_device_busy(struct device *dev, struct device_attribute *attr,
                char *buf)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        return snprintf(buf, 20, "%d\n", scsi_device_busy(sdev));
}
static DEVICE_ATTR(device_busy, S_IRUGO, sdev_show_device_busy, NULL);

static ssize_t
sdev_show_device_blocked(struct device *dev, struct device_attribute *attr,
                char *buf)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        return snprintf(buf, 20, "%d\n", atomic_read(&sdev->device_blocked));
}
static DEVICE_ATTR(device_blocked, S_IRUGO, sdev_show_device_blocked, NULL);

static ssize_t
sdev_show_unpriv_sgio (struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scsi_device *sdev;
        int bit;

        sdev = to_scsi_device(dev);
        bit = test_bit(QUEUE_FLAG_UNPRIV_SGIO, &sdev->request_queue->queue_flags);
        return snprintf(buf, 20, "%d\n", bit);
}

static ssize_t
sdev_store_unpriv_sgio (struct device *dev, struct device_attribute *attr,
                        const char *buf, size_t count)
{
        struct scsi_device *sdev;
        struct request_queue *q;
        int err;
        unsigned long val;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        sdev = to_scsi_device(dev);
        q = sdev->request_queue;
        err = kstrtoul(buf, 10, &val);
        if (err)
                return -EINVAL;

        if (val)
                blk_queue_flag_set(QUEUE_FLAG_UNPRIV_SGIO, q);
        else
                blk_queue_flag_clear(QUEUE_FLAG_UNPRIV_SGIO, q);
        return count;
}
static DEVICE_ATTR(unpriv_sgio, S_IRUGO | S_IWUSR, sdev_show_unpriv_sgio, sdev_store_unpriv_sgio);

/*
 * TODO: can we make these symlinks to the block layer ones?
 */
static ssize_t
sdev_show_timeout (struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scsi_device *sdev;
        sdev = to_scsi_device(dev);
        return snprintf(buf, 20, "%d\n", sdev->request_queue->rq_timeout / HZ);
}

static ssize_t
sdev_store_timeout (struct device *dev, struct device_attribute *attr,
                    const char *buf, size_t count)
{
        struct scsi_device *sdev;
        int timeout;
        sdev = to_scsi_device(dev);
        sscanf (buf, "%d\n", &timeout);
        blk_queue_rq_timeout(sdev->request_queue, timeout * HZ);
        return count;
}
static DEVICE_ATTR(timeout, S_IRUGO | S_IWUSR, sdev_show_timeout, sdev_store_timeout);

static ssize_t
sdev_show_eh_timeout(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scsi_device *sdev;
        sdev = to_scsi_device(dev);
        return snprintf(buf, 20, "%u\n", sdev->eh_timeout / HZ);
}

static ssize_t
sdev_store_eh_timeout(struct device *dev, struct device_attribute *attr,
                    const char *buf, size_t count)
{
        struct scsi_device *sdev;
        unsigned int eh_timeout;
        int err;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        sdev = to_scsi_device(dev);
        err = kstrtouint(buf, 10, &eh_timeout);
        if (err)
                return err;
        sdev->eh_timeout = eh_timeout * HZ;

        return count;
}
static DEVICE_ATTR(eh_timeout, S_IRUGO | S_IWUSR, sdev_show_eh_timeout, sdev_store_eh_timeout);

static ssize_t
store_rescan_field (struct device *dev, struct device_attribute *attr,
                    const char *buf, size_t count)
{
        scsi_rescan_device(dev);
        return count;
}
static DEVICE_ATTR(rescan, S_IWUSR, NULL, store_rescan_field);

static ssize_t
sdev_store_delete(struct device *dev, struct device_attribute *attr,
                  const char *buf, size_t count)
{
        struct kernfs_node *kn;
        struct scsi_device *sdev = to_scsi_device(dev);

        /*
         * We need to try to get module, avoiding the module been removed
         * during delete.
         */
        if (scsi_device_get(sdev))
                return -ENODEV;

        kn = sysfs_break_active_protection(&dev->kobj, &attr->attr);
        WARN_ON_ONCE(!kn);
        /*
         * Concurrent writes into the "delete" sysfs attribute may trigger
         * concurrent calls to device_remove_file() and scsi_remove_device().
         * device_remove_file() handles concurrent removal calls by
         * serializing these and by ignoring the second and later removal
         * attempts.  Concurrent calls of scsi_remove_device() are
         * serialized. The second and later calls of scsi_remove_device() are
         * ignored because the first call of that function changes the device
         * state into SDEV_DEL.
         */
        device_remove_file(dev, attr);
        scsi_remove_device(sdev);
        if (kn)
                sysfs_unbreak_active_protection(kn);
        scsi_device_put(sdev);
        return count;
};
static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete);

static ssize_t
store_state_field(struct device *dev, struct device_attribute *attr,
                  const char *buf, size_t count)
{
        int i, ret;
        struct scsi_device *sdev = to_scsi_device(dev);
        enum scsi_device_state state = 0;

        for (i = 0; i < ARRAY_SIZE(sdev_states); i++) {
                const int len = strlen(sdev_states[i].name);
                if (strncmp(sdev_states[i].name, buf, len) == 0 &&
                   buf[len] == '\n') {
                        state = sdev_states[i].value;
                        break;
                }
        }
        if (!state)
                return -EINVAL;

        mutex_lock(&sdev->state_mutex);
        ret = scsi_device_set_state(sdev, state);
        /*
         * If the device state changes to SDEV_RUNNING, we need to
         * run the queue to avoid I/O hang, and rescan the device
         * to revalidate it. Running the queue first is necessary
         * because another thread may be waiting inside
         * blk_mq_freeze_queue_wait() and because that call may be
         * waiting for pending I/O to finish.
         */
        if (ret == 0 && state == SDEV_RUNNING) {
                blk_mq_run_hw_queues(sdev->request_queue, true);
                scsi_rescan_device(dev);
        }
        mutex_unlock(&sdev->state_mutex);

        return ret == 0 ? count : -EINVAL;
}

static ssize_t
show_state_field(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        const char *name = scsi_device_state_name(sdev->sdev_state);

        if (!name)
                return -EINVAL;

        return snprintf(buf, 20, "%s\n", name);
}

static DEVICE_ATTR(state, S_IRUGO | S_IWUSR, show_state_field, store_state_field);

static ssize_t
show_queue_type_field(struct device *dev, struct device_attribute *attr,
                      char *buf)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        const char *name = "none";

        if (sdev->simple_tags)
                name = "simple";

        return snprintf(buf, 20, "%s\n", name);
}

static ssize_t
store_queue_type_field(struct device *dev, struct device_attribute *attr,
                       const char *buf, size_t count)
{
        struct scsi_device *sdev = to_scsi_device(dev);

        if (!sdev->tagged_supported)
                return -EINVAL;
                
        sdev_printk(KERN_INFO, sdev,
                    "ignoring write to deprecated queue_type attribute");
        return count;
}

static DEVICE_ATTR(queue_type, S_IRUGO | S_IWUSR, show_queue_type_field,
                   store_queue_type_field);

#define sdev_vpd_pg_attr(_page)                                         \
static ssize_t                                                  \
show_vpd_##_page(struct file *filp, struct kobject *kobj,       \
                 struct bin_attribute *bin_attr,                        \
                 char *buf, loff_t off, size_t count)                   \
{                                                                       \
        struct device *dev = kobj_to_dev(kobj);                         \
        struct scsi_device *sdev = to_scsi_device(dev);                 \
        struct scsi_vpd *vpd_page;                                      \
        int ret = -EINVAL;                                              \
                                                                        \
        rcu_read_lock();                                                \
        vpd_page = rcu_dereference(sdev->vpd_##_page);                  \
        if (vpd_page)                                                   \
                ret = memory_read_from_buffer(buf, count, &off,         \
                                vpd_page->data, vpd_page->len);         \
        rcu_read_unlock();                                              \
        return ret;                                                     \
}                                                                       \
static struct bin_attribute dev_attr_vpd_##_page = {            \
        .attr = {.name = __stringify(vpd_##_page), .mode = S_IRUGO },   \
        .size = 0,                                                      \
        .read = show_vpd_##_page,                                       \
};

sdev_vpd_pg_attr(pg83);
sdev_vpd_pg_attr(pg80);
sdev_vpd_pg_attr(pg89);
sdev_vpd_pg_attr(pg0);

static ssize_t show_inquiry(struct file *filep, struct kobject *kobj,
                            struct bin_attribute *bin_attr,
                            char *buf, loff_t off, size_t count)
{
        struct device *dev = kobj_to_dev(kobj);
        struct scsi_device *sdev = to_scsi_device(dev);

        if (!sdev->inquiry)
                return -EINVAL;

        return memory_read_from_buffer(buf, count, &off, sdev->inquiry,
                                       sdev->inquiry_len);
}

static struct bin_attribute dev_attr_inquiry = {
        .attr = {
                .name = "inquiry",
                .mode = S_IRUGO,
        },
        .size = 0,
        .read = show_inquiry,
};

static ssize_t
show_iostat_counterbits(struct device *dev, struct device_attribute *attr,
                        char *buf)
{
        return snprintf(buf, 20, "%d\n", (int)sizeof(atomic_t) * 8);
}

static DEVICE_ATTR(iocounterbits, S_IRUGO, show_iostat_counterbits, NULL);

#define show_sdev_iostat(field)                                         \
static ssize_t                                                          \
show_iostat_##field(struct device *dev, struct device_attribute *attr,  \
                    char *buf)                                          \
{                                                                       \
        struct scsi_device *sdev = to_scsi_device(dev);                 \
        unsigned long long count = atomic_read(&sdev->field);           \
        return snprintf(buf, 20, "0x%llx\n", count);                    \
}                                                                       \
static DEVICE_ATTR(field, S_IRUGO, show_iostat_##field, NULL)

show_sdev_iostat(iorequest_cnt);
show_sdev_iostat(iodone_cnt);
show_sdev_iostat(ioerr_cnt);

static ssize_t
sdev_show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scsi_device *sdev;
        sdev = to_scsi_device(dev);
        return snprintf (buf, 20, SCSI_DEVICE_MODALIAS_FMT "\n", sdev->type);
}
static DEVICE_ATTR(modalias, S_IRUGO, sdev_show_modalias, NULL);

#define DECLARE_EVT_SHOW(name, Cap_name)                                \

static ssize_t                                                          \
sdev_show_evt_##name(struct device *dev, struct device_attribute *attr, \
                     char *buf)                                         \
{                                                                       \
        struct scsi_device *sdev = to_scsi_device(dev);                 \
        int val = test_bit(SDEV_EVT_##Cap_name, sdev->supported_events);\
        return snprintf(buf, 20, "%d\n", val);                          \
}

#define DECLARE_EVT_STORE(name, Cap_name)                               \
static ssize_t                                                          \
sdev_store_evt_##name(struct device *dev, struct device_attribute *attr,\
                      const char *buf, size_t count)                    \
{                                                                       \
        struct scsi_device *sdev = to_scsi_device(dev);                 \
        int val = simple_strtoul(buf, NULL, 0);                         \
        if (val == 0)                                                   \
                clear_bit(SDEV_EVT_##Cap_name, sdev->supported_events); \
        else if (val == 1)                                              \
                set_bit(SDEV_EVT_##Cap_name, sdev->supported_events);   \
        else                                                            \
                return -EINVAL;                                         \
        return count;                                                   \
}

#define DECLARE_EVT(name, Cap_name)                                     \
        DECLARE_EVT_SHOW(name, Cap_name)                                \
        DECLARE_EVT_STORE(name, Cap_name)                               \
        static DEVICE_ATTR(evt_##name, S_IRUGO, sdev_show_evt_##name,   \
                           sdev_store_evt_##name);
#define REF_EVT(name) &dev_attr_evt_##name.attr

DECLARE_EVT(media_change, MEDIA_CHANGE)
DECLARE_EVT(inquiry_change_reported, INQUIRY_CHANGE_REPORTED)
DECLARE_EVT(capacity_change_reported, CAPACITY_CHANGE_REPORTED)
DECLARE_EVT(soft_threshold_reached, SOFT_THRESHOLD_REACHED_REPORTED)
DECLARE_EVT(mode_parameter_change_reported, MODE_PARAMETER_CHANGE_REPORTED)
DECLARE_EVT(lun_change_reported, LUN_CHANGE_REPORTED)

static ssize_t
sdev_store_queue_depth(struct device *dev, struct device_attribute *attr,
                       const char *buf, size_t count)
{
        int depth, retval;
        struct scsi_device *sdev = to_scsi_device(dev);
        struct scsi_host_template *sht = sdev->host->hostt;

        if (!sht->change_queue_depth)
                return -EINVAL;

        depth = simple_strtoul(buf, NULL, 0);

        if (depth < 1 || depth > sdev->host->can_queue)
                return -EINVAL;

        retval = sht->change_queue_depth(sdev, depth);
        if (retval < 0)
                return retval;

        sdev->max_queue_depth = sdev->queue_depth;

        return count;
}
sdev_show_function(queue_depth, "%d\n");

static DEVICE_ATTR(queue_depth, S_IRUGO | S_IWUSR, sdev_show_queue_depth,
                   sdev_store_queue_depth);

static ssize_t
sdev_show_wwid(struct device *dev, struct device_attribute *attr,
                    char *buf)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        ssize_t count;

        count = scsi_vpd_lun_id(sdev, buf, PAGE_SIZE);
        if (count > 0) {
                buf[count] = '\n';
                count++;
        }
        return count;
}
static DEVICE_ATTR(wwid, S_IRUGO, sdev_show_wwid, NULL);

#define BLIST_FLAG_NAME(name)                                   \
        [const_ilog2((__force __u64)BLIST_##name)] = #name
static const char *const sdev_bflags_name[] = {
#include "scsi_devinfo_tbl.c"
};
#undef BLIST_FLAG_NAME

static ssize_t
sdev_show_blacklist(struct device *dev, struct device_attribute *attr,
                    char *buf)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        int i;
        ssize_t len = 0;

        for (i = 0; i < sizeof(sdev->sdev_bflags) * BITS_PER_BYTE; i++) {
                const char *name = NULL;

                if (!(sdev->sdev_bflags & (__force blist_flags_t)BIT(i)))
                        continue;
                if (i < ARRAY_SIZE(sdev_bflags_name) && sdev_bflags_name[i])
                        name = sdev_bflags_name[i];

                if (name)
                        len += scnprintf(buf + len, PAGE_SIZE - len,
                                         "%s%s", len ? " " : "", name);
                else
                        len += scnprintf(buf + len, PAGE_SIZE - len,
                                         "%sINVALID_BIT(%d)", len ? " " : "", i);
        }
        if (len)
                len += scnprintf(buf + len, PAGE_SIZE - len, "\n");
        return len;
}
static DEVICE_ATTR(blacklist, S_IRUGO, sdev_show_blacklist, NULL);

#ifdef CONFIG_SCSI_DH
static ssize_t
sdev_show_dh_state(struct device *dev, struct device_attribute *attr,
                   char *buf)
{
        struct scsi_device *sdev = to_scsi_device(dev);

        if (!sdev->handler)
                return snprintf(buf, 20, "detached\n");

        return snprintf(buf, 20, "%s\n", sdev->handler->name);
}

static ssize_t
sdev_store_dh_state(struct device *dev, struct device_attribute *attr,
                    const char *buf, size_t count)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        int err = -EINVAL;

        if (sdev->sdev_state == SDEV_CANCEL ||
            sdev->sdev_state == SDEV_DEL)
                return -ENODEV;

        if (!sdev->handler) {
                /*
                 * Attach to a device handler
                 */
                err = scsi_dh_attach(sdev->request_queue, buf);
        } else if (!strncmp(buf, "activate", 8)) {
                /*
                 * Activate a device handler
                 */
                if (sdev->handler->activate)
                        err = sdev->handler->activate(sdev, NULL, NULL);
                else
                        err = 0;
        } else if (!strncmp(buf, "detach", 6)) {
                /*
                 * Detach from a device handler
                 */
                sdev_printk(KERN_WARNING, sdev,
                            "can't detach handler %s.\n",
                            sdev->handler->name);
                err = -EINVAL;
        }

        return err < 0 ? err : count;
}

static DEVICE_ATTR(dh_state, S_IRUGO | S_IWUSR, sdev_show_dh_state,
                   sdev_store_dh_state);

static ssize_t
sdev_show_access_state(struct device *dev,
                       struct device_attribute *attr,
                       char *buf)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        unsigned char access_state;
        const char *access_state_name;

        if (!sdev->handler)
                return -EINVAL;

        access_state = (sdev->access_state & SCSI_ACCESS_STATE_MASK);
        access_state_name = scsi_access_state_name(access_state);

        return sprintf(buf, "%s\n",
                       access_state_name ? access_state_name : "unknown");
}
static DEVICE_ATTR(access_state, S_IRUGO, sdev_show_access_state, NULL);

static ssize_t
sdev_show_preferred_path(struct device *dev,
                         struct device_attribute *attr,
                         char *buf)
{
        struct scsi_device *sdev = to_scsi_device(dev);

        if (!sdev->handler)
                return -EINVAL;

        if (sdev->access_state & SCSI_ACCESS_STATE_PREFERRED)
                return sprintf(buf, "1\n");
        else
                return sprintf(buf, "0\n");
}
static DEVICE_ATTR(preferred_path, S_IRUGO, sdev_show_preferred_path, NULL);
#endif

static ssize_t
sdev_show_queue_ramp_up_period(struct device *dev,
                               struct device_attribute *attr,
                               char *buf)
{
        struct scsi_device *sdev;
        sdev = to_scsi_device(dev);
        return snprintf(buf, 20, "%u\n",
                        jiffies_to_msecs(sdev->queue_ramp_up_period));
}

static ssize_t
sdev_store_queue_ramp_up_period(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        unsigned int period;

        if (kstrtouint(buf, 10, &period))
                return -EINVAL;

        sdev->queue_ramp_up_period = msecs_to_jiffies(period);
        return count;
}

static DEVICE_ATTR(queue_ramp_up_period, S_IRUGO | S_IWUSR,
                   sdev_show_queue_ramp_up_period,
                   sdev_store_queue_ramp_up_period);

static umode_t scsi_sdev_attr_is_visible(struct kobject *kobj,
                                         struct attribute *attr, int i)
{
        struct device *dev = kobj_to_dev(kobj);
        struct scsi_device *sdev = to_scsi_device(dev);


        if (attr == &dev_attr_queue_depth.attr &&
            !sdev->host->hostt->change_queue_depth)
                return S_IRUGO;

        if (attr == &dev_attr_queue_ramp_up_period.attr &&
            !sdev->host->hostt->change_queue_depth)
                return 0;

#ifdef CONFIG_SCSI_DH
        if (attr == &dev_attr_access_state.attr &&
            !sdev->handler)
                return 0;
        if (attr == &dev_attr_preferred_path.attr &&
            !sdev->handler)
                return 0;
#endif
        return attr->mode;
}

static umode_t scsi_sdev_bin_attr_is_visible(struct kobject *kobj,
                                             struct bin_attribute *attr, int i)
{
        struct device *dev = kobj_to_dev(kobj);
        struct scsi_device *sdev = to_scsi_device(dev);


        if (attr == &dev_attr_vpd_pg0 && !sdev->vpd_pg0)
                return 0;

        if (attr == &dev_attr_vpd_pg80 && !sdev->vpd_pg80)
                return 0;

        if (attr == &dev_attr_vpd_pg83 && !sdev->vpd_pg83)
                return 0;

        if (attr == &dev_attr_vpd_pg89 && !sdev->vpd_pg89)
                return 0;

        return S_IRUGO;
}

/* Default template for device attributes.  May NOT be modified */
static struct attribute *scsi_sdev_attrs[] = {
        &dev_attr_device_blocked.attr,
        &dev_attr_type.attr,
        &dev_attr_scsi_level.attr,
        &dev_attr_device_busy.attr,
        &dev_attr_vendor.attr,
        &dev_attr_model.attr,
        &dev_attr_rev.attr,
        &dev_attr_rescan.attr,
        &dev_attr_delete.attr,
        &dev_attr_state.attr,
        &dev_attr_unpriv_sgio.attr,
        &dev_attr_timeout.attr,
        &dev_attr_eh_timeout.attr,
        &dev_attr_iocounterbits.attr,
        &dev_attr_iorequest_cnt.attr,
        &dev_attr_iodone_cnt.attr,
        &dev_attr_ioerr_cnt.attr,
        &dev_attr_modalias.attr,
        &dev_attr_queue_depth.attr,
        &dev_attr_queue_type.attr,
        &dev_attr_wwid.attr,
        &dev_attr_blacklist.attr,
#ifdef CONFIG_SCSI_DH
        &dev_attr_dh_state.attr,
        &dev_attr_access_state.attr,
        &dev_attr_preferred_path.attr,
#endif
        &dev_attr_queue_ramp_up_period.attr,
        REF_EVT(media_change),
        REF_EVT(inquiry_change_reported),
        REF_EVT(capacity_change_reported),
        REF_EVT(soft_threshold_reached),
        REF_EVT(mode_parameter_change_reported),
        REF_EVT(lun_change_reported),
        NULL
};

static struct bin_attribute *scsi_sdev_bin_attrs[] = {
        &dev_attr_vpd_pg0,
        &dev_attr_vpd_pg83,
        &dev_attr_vpd_pg80,
        &dev_attr_vpd_pg89,
        &dev_attr_inquiry,
        NULL
};
static struct attribute_group scsi_sdev_attr_group = {
        .attrs =        scsi_sdev_attrs,
        .bin_attrs =    scsi_sdev_bin_attrs,
        .is_visible =   scsi_sdev_attr_is_visible,
        .is_bin_visible = scsi_sdev_bin_attr_is_visible,
};

static const struct attribute_group *scsi_sdev_attr_groups[] = {
        &scsi_sdev_attr_group,
        NULL
};

static int scsi_target_add(struct scsi_target *starget)
{
        int error;

        if (starget->state != STARGET_CREATED)
                return 0;

        error = device_add(&starget->dev);
        if (error) {
                dev_err(&starget->dev, "target device_add failed, error %d\n", error);
                return error;
        }
        transport_add_device(&starget->dev);
        starget->state = STARGET_RUNNING;

        pm_runtime_set_active(&starget->dev);
        pm_runtime_enable(&starget->dev);
        device_enable_async_suspend(&starget->dev);

        return 0;
}

/**
 * scsi_sysfs_add_sdev - add scsi device to sysfs
 * @sdev:       scsi_device to add
 *
 * Return value:
 *      0 on Success / non-zero on Failure
 **/
int scsi_sysfs_add_sdev(struct scsi_device *sdev)
{
        int error, i;
        struct request_queue *rq = sdev->request_queue;
        struct scsi_target *starget = sdev->sdev_target;

        error = scsi_target_add(starget);
        if (error)
                return error;

        transport_configure_device(&starget->dev);

        device_enable_async_suspend(&sdev->sdev_gendev);
        scsi_autopm_get_target(starget);
        pm_runtime_set_active(&sdev->sdev_gendev);
        pm_runtime_forbid(&sdev->sdev_gendev);
        pm_runtime_enable(&sdev->sdev_gendev);
        scsi_autopm_put_target(starget);

        scsi_autopm_get_device(sdev);

        scsi_dh_add_device(sdev);

        error = device_add(&sdev->sdev_gendev);
        if (error) {
                sdev_printk(KERN_INFO, sdev,
                                "failed to add device: %d\n", error);
                return error;
        }

        device_enable_async_suspend(&sdev->sdev_dev);
        error = device_add(&sdev->sdev_dev);
        if (error) {
                sdev_printk(KERN_INFO, sdev,
                                "failed to add class device: %d\n", error);
                device_del(&sdev->sdev_gendev);
                return error;
        }
        transport_add_device(&sdev->sdev_gendev);
        sdev->is_visible = 1;

        error = bsg_scsi_register_queue(rq, &sdev->sdev_gendev);
        if (error)
                /* we're treating error on bsg register as non-fatal,
                 * so pretend nothing went wrong */
                sdev_printk(KERN_INFO, sdev,
                            "Failed to register bsg queue, errno=%d\n", error);

        /* add additional host specific attributes */
        if (sdev->host->hostt->sdev_attrs) {
                for (i = 0; sdev->host->hostt->sdev_attrs[i]; i++) {
                        error = device_create_file(&sdev->sdev_gendev,
                                        sdev->host->hostt->sdev_attrs[i]);
                        if (error)
                                return error;
                }
        }

        if (sdev->host->hostt->sdev_groups) {
                error = sysfs_create_groups(&sdev->sdev_gendev.kobj,
                                sdev->host->hostt->sdev_groups);
                if (error)
                        return error;
        }

        scsi_autopm_put_device(sdev);
        return error;
}

void __scsi_remove_device(struct scsi_device *sdev)
{
        struct device *dev = &sdev->sdev_gendev;
        int res;

        /*
         * This cleanup path is not reentrant and while it is impossible
         * to get a new reference with scsi_device_get() someone can still
         * hold a previously acquired one.
         */
        if (sdev->sdev_state == SDEV_DEL)
                return;

        if (sdev->is_visible) {
                /*
                 * If scsi_internal_target_block() is running concurrently,
                 * wait until it has finished before changing the device state.
                 */
                mutex_lock(&sdev->state_mutex);
                /*
                 * If blocked, we go straight to DEL and restart the queue so
                 * any commands issued during driver shutdown (like sync
                 * cache) are errored immediately.
                 */
                res = scsi_device_set_state(sdev, SDEV_CANCEL);
                if (res != 0) {
                        res = scsi_device_set_state(sdev, SDEV_DEL);
                        if (res == 0)
                                scsi_start_queue(sdev);
                }
                mutex_unlock(&sdev->state_mutex);

                if (res != 0)
                        return;

                if (sdev->host->hostt->sdev_groups)
                        sysfs_remove_groups(&sdev->sdev_gendev.kobj,
                                        sdev->host->hostt->sdev_groups);

                bsg_unregister_queue(sdev->request_queue);
                device_unregister(&sdev->sdev_dev);
                transport_remove_device(dev);
                device_del(dev);
        } else
                put_device(&sdev->sdev_dev);

        /*
         * Stop accepting new requests and wait until all queuecommand() and
         * scsi_run_queue() invocations have finished before tearing down the
         * device.
         */
        mutex_lock(&sdev->state_mutex);
        scsi_device_set_state(sdev, SDEV_DEL);
        mutex_unlock(&sdev->state_mutex);

        blk_cleanup_queue(sdev->request_queue);
        cancel_work_sync(&sdev->requeue_work);

        if (sdev->host->hostt->slave_destroy)
                sdev->host->hostt->slave_destroy(sdev);
        transport_destroy_device(dev);

        /*
         * Paired with the kref_get() in scsi_sysfs_initialize().  We have
         * removed sysfs visibility from the device, so make the target
         * invisible if this was the last device underneath it.
         */
        scsi_target_reap(scsi_target(sdev));

        put_device(dev);
}

/**
 * scsi_remove_device - unregister a device from the scsi bus
 * @sdev:       scsi_device to unregister
 **/
void scsi_remove_device(struct scsi_device *sdev)
{
        struct Scsi_Host *shost = sdev->host;

        mutex_lock(&shost->scan_mutex);
        __scsi_remove_device(sdev);
        mutex_unlock(&shost->scan_mutex);
}
EXPORT_SYMBOL(scsi_remove_device);

static void __scsi_remove_target(struct scsi_target *starget)
{
        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
        unsigned long flags;
        struct scsi_device *sdev;

        spin_lock_irqsave(shost->host_lock, flags);
 restart:
        list_for_each_entry(sdev, &shost->__devices, siblings) {
                /*
                 * We cannot call scsi_device_get() here, as
                 * we might've been called from rmmod() causing
                 * scsi_device_get() to fail the module_is_live()
                 * check.
                 */
                if (sdev->channel != starget->channel ||
                    sdev->id != starget->id)
                        continue;
                if (sdev->sdev_state == SDEV_DEL ||
                    sdev->sdev_state == SDEV_CANCEL ||
                    !get_device(&sdev->sdev_gendev))
                        continue;
                spin_unlock_irqrestore(shost->host_lock, flags);
                scsi_remove_device(sdev);
                put_device(&sdev->sdev_gendev);
                spin_lock_irqsave(shost->host_lock, flags);
                goto restart;
        }
        spin_unlock_irqrestore(shost->host_lock, flags);
}

/**
 * scsi_remove_target - try to remove a target and all its devices
 * @dev: generic starget or parent of generic stargets to be removed
 *
 * Note: This is slightly racy.  It is possible that if the user
 * requests the addition of another device then the target won't be
 * removed.
 */
void scsi_remove_target(struct device *dev)
{
        struct Scsi_Host *shost = dev_to_shost(dev->parent);
        struct scsi_target *starget;
        unsigned long flags;

restart:
        spin_lock_irqsave(shost->host_lock, flags);
        list_for_each_entry(starget, &shost->__targets, siblings) {
                if (starget->state == STARGET_DEL ||
                    starget->state == STARGET_REMOVE ||
                    starget->state == STARGET_CREATED_REMOVE)
                        continue;
                if (starget->dev.parent == dev || &starget->dev == dev) {
                        kref_get(&starget->reap_ref);
                        if (starget->state == STARGET_CREATED)
                                starget->state = STARGET_CREATED_REMOVE;
                        else
                                starget->state = STARGET_REMOVE;
                        spin_unlock_irqrestore(shost->host_lock, flags);
                        __scsi_remove_target(starget);
                        scsi_target_reap(starget);
                        goto restart;
                }
        }
        spin_unlock_irqrestore(shost->host_lock, flags);
}
EXPORT_SYMBOL(scsi_remove_target);

int scsi_register_driver(struct device_driver *drv)
{
        drv->bus = &scsi_bus_type;

        return driver_register(drv);
}
EXPORT_SYMBOL(scsi_register_driver);

int scsi_register_interface(struct class_interface *intf)
{
        intf->class = &sdev_class;

        return class_interface_register(intf);
}
EXPORT_SYMBOL(scsi_register_interface);

/**
 * scsi_sysfs_add_host - add scsi host to subsystem
 * @shost:     scsi host struct to add to subsystem
 **/
int scsi_sysfs_add_host(struct Scsi_Host *shost)
{
        int error, i;

        /* add host specific attributes */
        if (shost->hostt->shost_attrs) {
                for (i = 0; shost->hostt->shost_attrs[i]; i++) {
                        error = device_create_file(&shost->shost_dev,
                                        shost->hostt->shost_attrs[i]);
                        if (error)
                                return error;
                }
        }

        transport_register_device(&shost->shost_gendev);
        transport_configure_device(&shost->shost_gendev);
        return 0;
}

static struct device_type scsi_dev_type = {
        .name =         "scsi_device",
        .release =      scsi_device_dev_release,
        .groups =       scsi_sdev_attr_groups,
};

void scsi_sysfs_device_initialize(struct scsi_device *sdev)
{
        unsigned long flags;
        struct Scsi_Host *shost = sdev->host;
        struct scsi_target  *starget = sdev->sdev_target;

        device_initialize(&sdev->sdev_gendev);
        sdev->sdev_gendev.bus = &scsi_bus_type;
        sdev->sdev_gendev.type = &scsi_dev_type;
        dev_set_name(&sdev->sdev_gendev, "%d:%d:%d:%llu",
                     sdev->host->host_no, sdev->channel, sdev->id, sdev->lun);

        device_initialize(&sdev->sdev_dev);
        sdev->sdev_dev.parent = get_device(&sdev->sdev_gendev);
        sdev->sdev_dev.class = &sdev_class;
        dev_set_name(&sdev->sdev_dev, "%d:%d:%d:%llu",
                     sdev->host->host_no, sdev->channel, sdev->id, sdev->lun);
        /*
         * Get a default scsi_level from the target (derived from sibling
         * devices).  This is the best we can do for guessing how to set
         * sdev->lun_in_cdb for the initial INQUIRY command.  For LUN 0 the
         * setting doesn't matter, because all the bits are zero anyway.
         * But it does matter for higher LUNs.
         */
        sdev->scsi_level = starget->scsi_level;
        if (sdev->scsi_level <= SCSI_2 &&
                        sdev->scsi_level != SCSI_UNKNOWN &&
                        !shost->no_scsi2_lun_in_cdb)
                sdev->lun_in_cdb = 1;

        transport_setup_device(&sdev->sdev_gendev);
        spin_lock_irqsave(shost->host_lock, flags);
        list_add_tail(&sdev->same_target_siblings, &starget->devices);
        list_add_tail(&sdev->siblings, &shost->__devices);
        spin_unlock_irqrestore(shost->host_lock, flags);
        /*
         * device can now only be removed via __scsi_remove_device() so hold
         * the target.  Target will be held in CREATED state until something
         * beneath it becomes visible (in which case it moves to RUNNING)
         */
        kref_get(&starget->reap_ref);
}

int scsi_is_sdev_device(const struct device *dev)
{
        return dev->type == &scsi_dev_type;
}
EXPORT_SYMBOL(scsi_is_sdev_device);

/* A blank transport template that is used in drivers that don't
 * yet implement Transport Attributes */
struct scsi_transport_template blank_transport_template = { { { {NULL, }, }, }, };