text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   *  hosts.c Copyright (C) 1992 Drew Eckhardt
   *          Copyright (C) 1993, 1994, 1995 Eric Youngdale
   *          Copyright (C) 2002-2003 Christoph Hellwig
   *
   *  mid to lowlevel SCSI driver interface
   *      Initial versions: Drew Eckhardt
   *      Subsequent revisions: Eric Youngdale
   *
   *  <drew@colorado.edu>
   *
   *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
   *  Added QLOGIC QLA1280 SCSI controller kernel host support. 
   *     August 4, 1999 Fred Lewis, Intel DuPont
   *
   *  Updated to reflect the new initialization scheme for the higher 
   *  level of scsi drivers (sd/sr/st)
   *  September 17, 2000 Torben Mathiasen <tmm@image.dk>
   *
   *  Restructured scsi_host lists and associated functions.
   *  September 04, 2002 Mike Anderson (andmike@us.ibm.com)
   */
  
  #include <linux/module.h>
  #include <linux/blkdev.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/kthread.h>
  #include <linux/string.h>
  #include <linux/mm.h>
  #include <linux/init.h>
  #include <linux/completion.h>
  #include <linux/transport_class.h>
  #include <linux/platform_device.h>
  #include <linux/pm_runtime.h>
  #include <linux/idr.h>
  #include <scsi/scsi_device.h>
  #include <scsi/scsi_host.h>
  #include <scsi/scsi_transport.h>
  #include <scsi/scsi_cmnd.h>
  
  #include "scsi_priv.h"
  #include "scsi_logging.h"
  
  
  static int shost_eh_deadline = -1;
  
  module_param_named(eh_deadline, shost_eh_deadline, int, S_IRUGO|S_IWUSR);
  MODULE_PARM_DESC(eh_deadline,
  		 "SCSI EH timeout in seconds (should be between 0 and 2^31-1)");
  
  static DEFINE_IDA(host_index_ida);
  
  
  static void scsi_host_cls_release(struct device *dev)
  {
  	put_device(&class_to_shost(dev)->shost_gendev);
  }
  
  static struct class shost_class = {
  	.name		= "scsi_host",
  	.dev_release	= scsi_host_cls_release,
  };
  
  /**
   *	scsi_host_set_state - Take the given host through the host state model.
   *	@shost:	scsi host to change the state of.
   *	@state:	state to change to.
   *
   *	Returns zero if unsuccessful or an error if the requested
   *	transition is illegal.
   **/
  int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
  {
  	enum scsi_host_state oldstate = shost->shost_state;
  
  	if (state == oldstate)
  		return 0;
  
  	switch (state) {
  	case SHOST_CREATED:
  		/* There are no legal states that come back to
  		 * created.  This is the manually initialised start
  		 * state */
  		goto illegal;
  
  	case SHOST_RUNNING:
  		switch (oldstate) {
  		case SHOST_CREATED:
  		case SHOST_RECOVERY:
  			break;
  		default:
  			goto illegal;
  		}
  		break;
  
  	case SHOST_RECOVERY:
  		switch (oldstate) {
  		case SHOST_RUNNING:
  			break;
  		default:
  			goto illegal;
  		}
  		break;
  
  	case SHOST_CANCEL:
  		switch (oldstate) {
  		case SHOST_CREATED:
  		case SHOST_RUNNING:
  		case SHOST_CANCEL_RECOVERY:
  			break;
  		default:
  			goto illegal;
  		}
  		break;
  
  	case SHOST_DEL:
  		switch (oldstate) {
  		case SHOST_CANCEL:
  		case SHOST_DEL_RECOVERY:
  			break;
  		default:
  			goto illegal;
  		}
  		break;
  
  	case SHOST_CANCEL_RECOVERY:
  		switch (oldstate) {
  		case SHOST_CANCEL:
  		case SHOST_RECOVERY:
  			break;
  		default:
  			goto illegal;
  		}
  		break;
  
  	case SHOST_DEL_RECOVERY:
  		switch (oldstate) {
  		case SHOST_CANCEL_RECOVERY:
  			break;
  		default:
  			goto illegal;
  		}
  		break;
  	}
  	shost->shost_state = state;
  	return 0;
  
   illegal:
  	SCSI_LOG_ERROR_RECOVERY(1,
  				shost_printk(KERN_ERR, shost,
  					     "Illegal host state transition"
  					     "%s->%s\n",
  					     scsi_host_state_name(oldstate),
  					     scsi_host_state_name(state)));
  	return -EINVAL;
  }
  
  /**
   * scsi_remove_host - remove a scsi host
   * @shost:	a pointer to a scsi host to remove
   **/
  void scsi_remove_host(struct Scsi_Host *shost)
  {
  	unsigned long flags;
  
  	mutex_lock(&shost->scan_mutex);
  	spin_lock_irqsave(shost->host_lock, flags);
  	if (scsi_host_set_state(shost, SHOST_CANCEL))
  		if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
  			spin_unlock_irqrestore(shost->host_lock, flags);
  			mutex_unlock(&shost->scan_mutex);
  			return;
  		}
  	spin_unlock_irqrestore(shost->host_lock, flags);
  
  	scsi_autopm_get_host(shost);
  	flush_workqueue(shost->tmf_work_q);
  	scsi_forget_host(shost);
  	mutex_unlock(&shost->scan_mutex);
  	scsi_proc_host_rm(shost);
  
  	spin_lock_irqsave(shost->host_lock, flags);
  	if (scsi_host_set_state(shost, SHOST_DEL))
  		BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
  	spin_unlock_irqrestore(shost->host_lock, flags);
  
  	transport_unregister_device(&shost->shost_gendev);
  	device_unregister(&shost->shost_dev);
  	device_del(&shost->shost_gendev);
  }
  EXPORT_SYMBOL(scsi_remove_host);
  
  /**
   * scsi_add_host_with_dma - add a scsi host with dma device
   * @shost:	scsi host pointer to add
   * @dev:	a struct device of type scsi class
   * @dma_dev:	dma device for the host
   *
   * Note: You rarely need to worry about this unless you're in a
   * virtualised host environments, so use the simpler scsi_add_host()
   * function instead.
   *
   * Return value: 
   * 	0 on success / != 0 for error
   **/
  int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
  			   struct device *dma_dev)
  {
  	struct scsi_host_template *sht = shost->hostt;
  	int error = -EINVAL;
  
  	shost_printk(KERN_INFO, shost, "%s\n",
  			sht->info ? sht->info(shost) : sht->name);
  
  	if (!shost->can_queue) {
  		shost_printk(KERN_ERR, shost,
  			     "can_queue = 0 no longer supported\n");
  		goto fail;
  	}
  
  	/* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */
  	shost->cmd_per_lun = min_t(int, shost->cmd_per_lun,
  				   shost->can_queue);
  
  	error = scsi_init_sense_cache(shost);
  	if (error)
  		goto fail;
  
  	error = scsi_mq_setup_tags(shost);
  	if (error)
  		goto fail;
  
  	if (!shost->shost_gendev.parent)
  		shost->shost_gendev.parent = dev ? dev : &platform_bus;
  	if (!dma_dev)
  		dma_dev = shost->shost_gendev.parent;
  
  	shost->dma_dev = dma_dev;
  
  	/*
  	 * Increase usage count temporarily here so that calling
  	 * scsi_autopm_put_host() will trigger runtime idle if there is
  	 * nothing else preventing suspending the device.
  	 */
  	pm_runtime_get_noresume(&shost->shost_gendev);
  	pm_runtime_set_active(&shost->shost_gendev);
  	pm_runtime_enable(&shost->shost_gendev);
  	device_enable_async_suspend(&shost->shost_gendev);
  
  	error = device_add(&shost->shost_gendev);
  	if (error)
  		goto out_disable_runtime_pm;
  
  	scsi_host_set_state(shost, SHOST_RUNNING);
  	get_device(shost->shost_gendev.parent);
  
  	device_enable_async_suspend(&shost->shost_dev);
  
  	get_device(&shost->shost_gendev);
  	error = device_add(&shost->shost_dev);
  	if (error)
  		goto out_del_gendev;
  
  	if (shost->transportt->host_size) {
  		shost->shost_data = kzalloc(shost->transportt->host_size,
  					 GFP_KERNEL);
  		if (shost->shost_data == NULL) {
  			error = -ENOMEM;
  			goto out_del_dev;
  		}
  	}
  
  	if (shost->transportt->create_work_queue) {
  		snprintf(shost->work_q_name, sizeof(shost->work_q_name),
  			 "scsi_wq_%d", shost->host_no);
  		shost->work_q = alloc_workqueue("%s",
  			WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | WQ_UNBOUND,
  			1, shost->work_q_name);
  
  		if (!shost->work_q) {
  			error = -EINVAL;
  			goto out_del_dev;
  		}
  	}
  
  	error = scsi_sysfs_add_host(shost);
  	if (error)
  		goto out_del_dev;
  
  	scsi_proc_host_add(shost);
  	scsi_autopm_put_host(shost);
  	return error;
  
  	/*
  	 * Any host allocation in this function will be freed in
  	 * scsi_host_dev_release().
  	 */
   out_del_dev:
  	device_del(&shost->shost_dev);
   out_del_gendev:
  	/*
  	 * Host state is SHOST_RUNNING so we have to explicitly release
  	 * ->shost_dev.
  	 */
  	put_device(&shost->shost_dev);
  	device_del(&shost->shost_gendev);
   out_disable_runtime_pm:
  	device_disable_async_suspend(&shost->shost_gendev);
  	pm_runtime_disable(&shost->shost_gendev);
  	pm_runtime_set_suspended(&shost->shost_gendev);
  	pm_runtime_put_noidle(&shost->shost_gendev);
   fail:
  	return error;
  }
  EXPORT_SYMBOL(scsi_add_host_with_dma);
  
  static void scsi_host_dev_release(struct device *dev)
  {
  	struct Scsi_Host *shost = dev_to_shost(dev);
  	struct device *parent = dev->parent;
  
  	scsi_proc_hostdir_rm(shost->hostt);
  
  	/* Wait for functions invoked through call_rcu(&scmd->rcu, ...) */
  	rcu_barrier();
  
  	if (shost->tmf_work_q)
  		destroy_workqueue(shost->tmf_work_q);
  	if (shost->ehandler)
  		kthread_stop(shost->ehandler);
  	if (shost->work_q)
  		destroy_workqueue(shost->work_q);
  
  	if (shost->shost_state == SHOST_CREATED) {
  		/*
  		 * Free the shost_dev device name here if scsi_host_alloc()
  		 * and scsi_host_put() have been called but neither
  		 * scsi_host_add() nor scsi_host_remove() has been called.
  		 * This avoids that the memory allocated for the shost_dev
  		 * name is leaked.
  		 */
  		kfree(dev_name(&shost->shost_dev));
  	}
  
  	if (shost->tag_set.tags)
  		scsi_mq_destroy_tags(shost);
  
  	kfree(shost->shost_data);
  
  	ida_simple_remove(&host_index_ida, shost->host_no);
  
  	if (shost->shost_state != SHOST_CREATED)
  		put_device(parent);
  	kfree(shost);
  }
  
  static struct device_type scsi_host_type = {
  	.name =		"scsi_host",
  	.release =	scsi_host_dev_release,
  };
  
  /**
   * scsi_host_alloc - register a scsi host adapter instance.
   * @sht:	pointer to scsi host template
   * @privsize:	extra bytes to allocate for driver
   *
   * Note:
   * 	Allocate a new Scsi_Host and perform basic initialization.
   * 	The host is not published to the scsi midlayer until scsi_add_host
   * 	is called.
   *
   * Return value:
   * 	Pointer to a new Scsi_Host
   **/
  struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
  {
  	struct Scsi_Host *shost;
  	int index, i, j = 0;
  
  	shost = kzalloc(sizeof(struct Scsi_Host) + privsize, GFP_KERNEL);
  	if (!shost)
  		return NULL;
  
  	shost->host_lock = &shost->default_lock;
  	spin_lock_init(shost->host_lock);
  	shost->shost_state = SHOST_CREATED;
  	INIT_LIST_HEAD(&shost->__devices);
  	INIT_LIST_HEAD(&shost->__targets);
  	INIT_LIST_HEAD(&shost->eh_cmd_q);
  	INIT_LIST_HEAD(&shost->starved_list);
  	init_waitqueue_head(&shost->host_wait);
  	mutex_init(&shost->scan_mutex);
  
  	index = ida_simple_get(&host_index_ida, 0, 0, GFP_KERNEL);
  	if (index < 0) {
  		kfree(shost);
  		return NULL;
  	}
  	shost->host_no = index;
  
  	shost->dma_channel = 0xff;
  
  	/* These three are default values which can be overridden */
  	shost->max_channel = 0;
  	shost->max_id = 8;
  	shost->max_lun = 8;
  
  	/* Give each shost a default transportt */
  	shost->transportt = &blank_transport_template;
  
  	/*
  	 * All drivers right now should be able to handle 12 byte
  	 * commands.  Every so often there are requests for 16 byte
  	 * commands, but individual low-level drivers need to certify that
  	 * they actually do something sensible with such commands.
  	 */
  	shost->max_cmd_len = 12;
  	shost->hostt = sht;
  	shost->this_id = sht->this_id;
  	shost->can_queue = sht->can_queue;
  	shost->sg_tablesize = sht->sg_tablesize;
  	shost->sg_prot_tablesize = sht->sg_prot_tablesize;
  	shost->cmd_per_lun = sht->cmd_per_lun;
  	shost->no_write_same = sht->no_write_same;
  	shost->host_tagset = sht->host_tagset;
  
  	if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
  		shost->eh_deadline = -1;
  	else if ((ulong) shost_eh_deadline * HZ > INT_MAX) {
  		shost_printk(KERN_WARNING, shost,
  			     "eh_deadline %u too large, setting to %u\n",
  			     shost_eh_deadline, INT_MAX / HZ);
  		shost->eh_deadline = INT_MAX;
  	} else
  		shost->eh_deadline = shost_eh_deadline * HZ;
  
  	if (sht->supported_mode == MODE_UNKNOWN)
  		/* means we didn't set it ... default to INITIATOR */
  		shost->active_mode = MODE_INITIATOR;
  	else
  		shost->active_mode = sht->supported_mode;
  
  	if (sht->max_host_blocked)
  		shost->max_host_blocked = sht->max_host_blocked;
  	else
  		shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
  
  	/*
  	 * If the driver imposes no hard sector transfer limit, start at
  	 * machine infinity initially.
  	 */
  	if (sht->max_sectors)
  		shost->max_sectors = sht->max_sectors;
  	else
  		shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
  
  	if (sht->max_segment_size)
  		shost->max_segment_size = sht->max_segment_size;
  	else
  		shost->max_segment_size = BLK_MAX_SEGMENT_SIZE;
  
  	/*
  	 * assume a 4GB boundary, if not set
  	 */
  	if (sht->dma_boundary)
  		shost->dma_boundary = sht->dma_boundary;
  	else
  		shost->dma_boundary = 0xffffffff;
  
  	if (sht->virt_boundary_mask)
  		shost->virt_boundary_mask = sht->virt_boundary_mask;
  
  	device_initialize(&shost->shost_gendev);
  	dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
  	shost->shost_gendev.bus = &scsi_bus_type;
  	shost->shost_gendev.type = &scsi_host_type;
  	scsi_enable_async_suspend(&shost->shost_gendev);
  
  	device_initialize(&shost->shost_dev);
  	shost->shost_dev.parent = &shost->shost_gendev;
  	shost->shost_dev.class = &shost_class;
  	dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
  	shost->shost_dev.groups = shost->shost_dev_attr_groups;
  	shost->shost_dev_attr_groups[j++] = &scsi_shost_attr_group;
  	if (sht->shost_groups) {
  		for (i = 0; sht->shost_groups[i] &&
  			     j < ARRAY_SIZE(shost->shost_dev_attr_groups);
  		     i++, j++) {
  			shost->shost_dev_attr_groups[j] =
  				sht->shost_groups[i];
  		}
  	}
  	WARN_ON_ONCE(j >= ARRAY_SIZE(shost->shost_dev_attr_groups));
  
  	shost->ehandler = kthread_run(scsi_error_handler, shost,
  			"scsi_eh_%d", shost->host_no);
  	if (IS_ERR(shost->ehandler)) {
  		shost_printk(KERN_WARNING, shost,
  			"error handler thread failed to spawn, error = %ld\n",
  			PTR_ERR(shost->ehandler));
  		shost->ehandler = NULL;
  		goto fail;
  	}
  
  	shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
  					WQ_UNBOUND | WQ_MEM_RECLAIM | WQ_SYSFS,
  					   1, shost->host_no);
  	if (!shost->tmf_work_q) {
  		shost_printk(KERN_WARNING, shost,
  			     "failed to create tmf workq\n");
  		goto fail;
  	}
  	scsi_proc_hostdir_add(shost->hostt);
  	return shost;
   fail:
  	/*
  	 * Host state is still SHOST_CREATED and that is enough to release
  	 * ->shost_gendev. scsi_host_dev_release() will free
  	 * dev_name(&shost->shost_dev).
  	 */
  	put_device(&shost->shost_gendev);
  
  	return NULL;
  }
  EXPORT_SYMBOL(scsi_host_alloc);
  
  static int __scsi_host_match(struct device *dev, const void *data)
  {
  	struct Scsi_Host *p;
  	const unsigned short *hostnum = data;
  
  	p = class_to_shost(dev);
  	return p->host_no == *hostnum;
  }
  
  /**
   * scsi_host_lookup - get a reference to a Scsi_Host by host no
   * @hostnum:	host number to locate
   *
   * Return value:
   *	A pointer to located Scsi_Host or NULL.
   *
   *	The caller must do a scsi_host_put() to drop the reference
   *	that scsi_host_get() took. The put_device() below dropped
   *	the reference from class_find_device().
   **/
  struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
  {
  	struct device *cdev;
  	struct Scsi_Host *shost = NULL;
  
  	cdev = class_find_device(&shost_class, NULL, &hostnum,
  				 __scsi_host_match);
  	if (cdev) {
  		shost = scsi_host_get(class_to_shost(cdev));
  		put_device(cdev);
  	}
  	return shost;
  }
  EXPORT_SYMBOL(scsi_host_lookup);
  
  /**
   * scsi_host_get - inc a Scsi_Host ref count
   * @shost:	Pointer to Scsi_Host to inc.
   **/
  struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
  {
  	if ((shost->shost_state == SHOST_DEL) ||
  		!get_device(&shost->shost_gendev))
  		return NULL;
  	return shost;
  }
  EXPORT_SYMBOL(scsi_host_get);
  
  static bool scsi_host_check_in_flight(struct request *rq, void *data,
  				      bool reserved)
  {
  	int *count = data;
  	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
  
  	if (test_bit(SCMD_STATE_INFLIGHT, &cmd->state))
  		(*count)++;
  
  	return true;
  }
  
  /**
   * scsi_host_busy - Return the host busy counter
   * @shost:	Pointer to Scsi_Host to inc.
   **/
  int scsi_host_busy(struct Scsi_Host *shost)
  {
  	int cnt = 0;
  
  	blk_mq_tagset_busy_iter(&shost->tag_set,
  				scsi_host_check_in_flight, &cnt);
  	return cnt;
  }
  EXPORT_SYMBOL(scsi_host_busy);
  
  /**
   * scsi_host_put - dec a Scsi_Host ref count
   * @shost:	Pointer to Scsi_Host to dec.
   **/
  void scsi_host_put(struct Scsi_Host *shost)
  {
  	put_device(&shost->shost_gendev);
  }
  EXPORT_SYMBOL(scsi_host_put);
  
  int scsi_init_hosts(void)
  {
  	return class_register(&shost_class);
  }
  
  void scsi_exit_hosts(void)
  {
  	class_unregister(&shost_class);
  	ida_destroy(&host_index_ida);
  }
  
  int scsi_is_host_device(const struct device *dev)
  {
  	return dev->type == &scsi_host_type;
  }
  EXPORT_SYMBOL(scsi_is_host_device);
  
  /**
   * scsi_queue_work - Queue work to the Scsi_Host workqueue.
   * @shost:	Pointer to Scsi_Host.
   * @work:	Work to queue for execution.
   *
   * Return value:
   * 	1 - work queued for execution
   *	0 - work is already queued
   *	-EINVAL - work queue doesn't exist
   **/
  int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
  {
  	if (unlikely(!shost->work_q)) {
  		shost_printk(KERN_ERR, shost,
  			"ERROR: Scsi host '%s' attempted to queue scsi-work, "
  			"when no workqueue created.\n", shost->hostt->name);
  		dump_stack();
  
  		return -EINVAL;
  	}
  
  	return queue_work(shost->work_q, work);
  }
  EXPORT_SYMBOL_GPL(scsi_queue_work);
  
  /**
   * scsi_flush_work - Flush a Scsi_Host's workqueue.
   * @shost:	Pointer to Scsi_Host.
   **/
  void scsi_flush_work(struct Scsi_Host *shost)
  {
  	if (!shost->work_q) {
  		shost_printk(KERN_ERR, shost,
  			"ERROR: Scsi host '%s' attempted to flush scsi-work, "
  			"when no workqueue created.\n", shost->hostt->name);
  		dump_stack();
  		return;
  	}
  
  	flush_workqueue(shost->work_q);
  }
  EXPORT_SYMBOL_GPL(scsi_flush_work);
  
  static bool complete_all_cmds_iter(struct request *rq, void *data, bool rsvd)
  {
  	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
  	enum scsi_host_status status = *(enum scsi_host_status *)data;
  
  	scsi_dma_unmap(scmd);
  	scmd->result = 0;
  	set_host_byte(scmd, status);
  	scsi_done(scmd);
  	return true;
  }
  
  /**
   * scsi_host_complete_all_commands - Terminate all running commands
   * @shost:	Scsi Host on which commands should be terminated
   * @status:	Status to be set for the terminated commands
   *
   * There is no protection against modification of the number
   * of outstanding commands. It is the responsibility of the
   * caller to ensure that concurrent I/O submission and/or
   * completion is stopped when calling this function.
   */
  void scsi_host_complete_all_commands(struct Scsi_Host *shost,
  				     enum scsi_host_status status)
  {
  	blk_mq_tagset_busy_iter(&shost->tag_set, complete_all_cmds_iter,
  				&status);
  }
  EXPORT_SYMBOL_GPL(scsi_host_complete_all_commands);
  
  struct scsi_host_busy_iter_data {
  	bool (*fn)(struct scsi_cmnd *, void *, bool);
  	void *priv;
  };
  
  static bool __scsi_host_busy_iter_fn(struct request *req, void *priv,
  				   bool reserved)
  {
  	struct scsi_host_busy_iter_data *iter_data = priv;
  	struct scsi_cmnd *sc = blk_mq_rq_to_pdu(req);
  
  	return iter_data->fn(sc, iter_data->priv, reserved);
  }
  
  /**
   * scsi_host_busy_iter - Iterate over all busy commands
   * @shost:	Pointer to Scsi_Host.
   * @fn:		Function to call on each busy command
   * @priv:	Data pointer passed to @fn
   *
   * If locking against concurrent command completions is required
   * ithas to be provided by the caller
   **/
  void scsi_host_busy_iter(struct Scsi_Host *shost,
  			 bool (*fn)(struct scsi_cmnd *, void *, bool),
  			 void *priv)
  {
  	struct scsi_host_busy_iter_data iter_data = {
  		.fn = fn,
  		.priv = priv,
  	};
  
  	blk_mq_tagset_busy_iter(&shost->tag_set, __scsi_host_busy_iter_fn,
  				&iter_data);
  }
  EXPORT_SYMBOL_GPL(scsi_host_busy_iter);
  