drivers/scsi/hosts.c - kernel/msm-4.9 - Gitiles

 /*
  *  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/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 <scsi/scsi_device.h>
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_transport.h>

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


 static int scsi_host_next_hn;		/* host_no for next new host */


 static void scsi_host_cls_release(struct class_device *class_dev)
 {
 	put_device(&class_to_shost(class_dev)->shost_gendev);
 }

 static struct class shost_class = {
 	.name		= "scsi_host",
 	.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;
 }
 EXPORT_SYMBOL(scsi_host_set_state);

 /**
  * 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);
 	mutex_unlock(&shost->scan_mutex);
 	scsi_forget_host(shost);
 	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);
 	class_device_unregister(&shost->shost_classdev);
 	device_del(&shost->shost_gendev);
 	scsi_proc_hostdir_rm(shost->hostt);
 }
 EXPORT_SYMBOL(scsi_remove_host);

 /**
  * scsi_add_host - add a scsi host
  * @shost:	scsi host pointer to add
  * @dev:	a struct device of type scsi class
  *
  * Return value:
  * 	0 on success / != 0 for error
  **/
 int scsi_add_host(struct Scsi_Host *shost, struct device *dev)
 {
 	struct scsi_host_template *sht = shost->hostt;
 	int error = -EINVAL;

 	printk(KERN_INFO "scsi%d : %s\n", shost->host_no,
 			sht->info ? sht->info(shost) : sht->name);

 	if (!shost->can_queue) {
 		printk(KERN_ERR "%s: can_queue = 0 no longer supported\n",
 				sht->name);
 		goto out;
 	}

 	if (!shost->shost_gendev.parent)
 		shost->shost_gendev.parent = dev ? dev : &platform_bus;

 	error = device_add(&shost->shost_gendev);
 	if (error)
 		goto out;

 	scsi_host_set_state(shost, SHOST_RUNNING);
 	get_device(shost->shost_gendev.parent);

 	error = class_device_add(&shost->shost_classdev);
 	if (error)
 		goto out_del_gendev;

 	get_device(&shost->shost_gendev);

 	if (shost->transportt->host_size &&
 	    (shost->shost_data = kzalloc(shost->transportt->host_size,
 					 GFP_KERNEL)) == NULL)
 		goto out_del_classdev;

 	if (shost->transportt->create_work_queue) {
 		snprintf(shost->work_q_name, KOBJ_NAME_LEN, "scsi_wq_%d",
 			shost->host_no);
 		shost->work_q = create_singlethread_workqueue(
 					shost->work_q_name);
 		if (!shost->work_q)
 			goto out_free_shost_data;
 	}

 	error = scsi_sysfs_add_host(shost);
 	if (error)
 		goto out_destroy_host;

 	scsi_proc_host_add(shost);
 	return error;

  out_destroy_host:
 	if (shost->work_q)
 		destroy_workqueue(shost->work_q);
  out_free_shost_data:
 	kfree(shost->shost_data);
  out_del_classdev:
 	class_device_del(&shost->shost_classdev);
  out_del_gendev:
 	device_del(&shost->shost_gendev);
  out:
 	return error;
 }
 EXPORT_SYMBOL(scsi_add_host);

 static void scsi_host_dev_release(struct device *dev)
 {
 	struct Scsi_Host *shost = dev_to_shost(dev);
 	struct device *parent = dev->parent;

 	if (shost->ehandler)
 		kthread_stop(shost->ehandler);
 	if (shost->work_q)
 		destroy_workqueue(shost->work_q);
 	if (shost->uspace_req_q) {
 		kfree(shost->uspace_req_q->queuedata);
 		scsi_free_queue(shost->uspace_req_q);
 	}

 	scsi_destroy_command_freelist(shost);
 	if (shost->bqt)
 		blk_free_tags(shost->bqt);

 	kfree(shost->shost_data);

 	if (parent)
 		put_device(parent);
 	kfree(shost);
 }

 /**
  * 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;
 	gfp_t gfp_mask = GFP_KERNEL;
 	int rval;

 	if (sht->unchecked_isa_dma && privsize)
 		gfp_mask |= __GFP_DMA;

 	shost = kzalloc(sizeof(struct Scsi_Host) + privsize, gfp_mask);
 	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);

 	shost->host_no = scsi_host_next_hn++; /* XXX(hch): still racy */
 	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->cmd_per_lun = sht->cmd_per_lun;
 	shost->unchecked_isa_dma = sht->unchecked_isa_dma;
 	shost->use_clustering = sht->use_clustering;
 	shost->ordered_tag = sht->ordered_tag;
 	shost->active_mode = sht->supported_mode;
 	shost->use_sg_chaining = sht->use_sg_chaining;

 	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;

 	/*
 	 * assume a 4GB boundary, if not set
 	 */
 	if (sht->dma_boundary)
 		shost->dma_boundary = sht->dma_boundary;
 	else
 		shost->dma_boundary = 0xffffffff;

 	rval = scsi_setup_command_freelist(shost);
 	if (rval)
 		goto fail_kfree;

 	device_initialize(&shost->shost_gendev);
 	snprintf(shost->shost_gendev.bus_id, BUS_ID_SIZE, "host%d",
 		shost->host_no);
 	shost->shost_gendev.release = scsi_host_dev_release;

 	class_device_initialize(&shost->shost_classdev);
 	shost->shost_classdev.dev = &shost->shost_gendev;
 	shost->shost_classdev.class = &shost_class;
 	snprintf(shost->shost_classdev.class_id, BUS_ID_SIZE, "host%d",
 		  shost->host_no);

 	shost->ehandler = kthread_run(scsi_error_handler, shost,
 			"scsi_eh_%d", shost->host_no);
 	if (IS_ERR(shost->ehandler)) {
 		rval = PTR_ERR(shost->ehandler);
 		goto fail_destroy_freelist;
 	}

 	scsi_proc_hostdir_add(shost->hostt);
 	return shost;

  fail_destroy_freelist:
 	scsi_destroy_command_freelist(shost);
  fail_kfree:
 	kfree(shost);
 	return NULL;
 }
 EXPORT_SYMBOL(scsi_host_alloc);

 struct Scsi_Host *scsi_register(struct scsi_host_template *sht, int privsize)
 {
 	struct Scsi_Host *shost = scsi_host_alloc(sht, privsize);

 	if (!sht->detect) {
 		printk(KERN_WARNING "scsi_register() called on new-style "
 				    "template for driver %s\n", sht->name);
 		dump_stack();
 	}

 	if (shost)
 		list_add_tail(&shost->sht_legacy_list, &sht->legacy_hosts);
 	return shost;
 }
 EXPORT_SYMBOL(scsi_register);

 void scsi_unregister(struct Scsi_Host *shost)
 {
 	list_del(&shost->sht_legacy_list);
 	scsi_host_put(shost);
 }
 EXPORT_SYMBOL(scsi_unregister);

 static int __scsi_host_match(struct class_device *cdev, void *data)
 {
 	struct Scsi_Host *p;
 	unsigned short *hostnum = (unsigned short *)data;

 	p = class_to_shost(cdev);
 	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.
  **/
 struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
 {
 	struct class_device *cdev;
 	struct Scsi_Host *shost = ERR_PTR(-ENXIO);

 	cdev = class_find_child(&shost_class, &hostnum, __scsi_host_match);
 	if (cdev)
 		shost = scsi_host_get(class_to_shost(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);

 /**
  * 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);
 }

 int scsi_is_host_device(const struct device *dev)
 {
 	return dev->release == scsi_host_dev_release;
 }
 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)) {
 		printk(KERN_ERR
 			"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) {
 		printk(KERN_ERR
 			"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);
	/*
	* 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/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 <scsi/scsi_device.h>
	#include <scsi/scsi_host.h>
	#include <scsi/scsi_transport.h>

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


	static int scsi_host_next_hn; /* host_no for next new host */


	static void scsi_host_cls_release(struct class_device *class_dev)
	{
	put_device(&class_to_shost(class_dev)->shost_gendev);
	}

	static struct class shost_class = {
	.name = "scsi_host",
	.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;
	}
	EXPORT_SYMBOL(scsi_host_set_state);

	/**
	* 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);
	mutex_unlock(&shost->scan_mutex);
	scsi_forget_host(shost);
	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);
	class_device_unregister(&shost->shost_classdev);
	device_del(&shost->shost_gendev);
	scsi_proc_hostdir_rm(shost->hostt);
	}
	EXPORT_SYMBOL(scsi_remove_host);

	/**
	* scsi_add_host - add a scsi host
	* @shost: scsi host pointer to add
	* @dev: a struct device of type scsi class
	*
	* Return value:
	* 0 on success / != 0 for error
	**/
	int scsi_add_host(struct Scsi_Host shost, struct device dev)
	{
	struct scsi_host_template *sht = shost->hostt;
	int error = -EINVAL;

	printk(KERN_INFO "scsi%d : %s\n", shost->host_no,
	sht->info ? sht->info(shost) : sht->name);

	if (!shost->can_queue) {
	printk(KERN_ERR "%s: can_queue = 0 no longer supported\n",
	sht->name);
	goto out;
	}

	if (!shost->shost_gendev.parent)
	shost->shost_gendev.parent = dev ? dev : &platform_bus;

	error = device_add(&shost->shost_gendev);
	if (error)
	goto out;

	scsi_host_set_state(shost, SHOST_RUNNING);
	get_device(shost->shost_gendev.parent);

	error = class_device_add(&shost->shost_classdev);
	if (error)
	goto out_del_gendev;

	get_device(&shost->shost_gendev);

	if (shost->transportt->host_size &&
	(shost->shost_data = kzalloc(shost->transportt->host_size,
	GFP_KERNEL)) == NULL)
	goto out_del_classdev;

	if (shost->transportt->create_work_queue) {
	snprintf(shost->work_q_name, KOBJ_NAME_LEN, "scsi_wq_%d",
	shost->host_no);
	shost->work_q = create_singlethread_workqueue(
	shost->work_q_name);
	if (!shost->work_q)
	goto out_free_shost_data;
	}

	error = scsi_sysfs_add_host(shost);
	if (error)
	goto out_destroy_host;

	scsi_proc_host_add(shost);
	return error;

	out_destroy_host:
	if (shost->work_q)
	destroy_workqueue(shost->work_q);
	out_free_shost_data:
	kfree(shost->shost_data);
	out_del_classdev:
	class_device_del(&shost->shost_classdev);
	out_del_gendev:
	device_del(&shost->shost_gendev);
	out:
	return error;
	}
	EXPORT_SYMBOL(scsi_add_host);

	static void scsi_host_dev_release(struct device *dev)
	{
	struct Scsi_Host *shost = dev_to_shost(dev);
	struct device *parent = dev->parent;

	if (shost->ehandler)
	kthread_stop(shost->ehandler);
	if (shost->work_q)
	destroy_workqueue(shost->work_q);
	if (shost->uspace_req_q) {
	kfree(shost->uspace_req_q->queuedata);
	scsi_free_queue(shost->uspace_req_q);
	}

	scsi_destroy_command_freelist(shost);
	if (shost->bqt)
	blk_free_tags(shost->bqt);

	kfree(shost->shost_data);

	if (parent)
	put_device(parent);
	kfree(shost);
	}

	/**
	* 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;
	gfp_t gfp_mask = GFP_KERNEL;
	int rval;

	if (sht->unchecked_isa_dma && privsize)
	gfp_mask \|= __GFP_DMA;

	shost = kzalloc(sizeof(struct Scsi_Host) + privsize, gfp_mask);
	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);

	shost->host_no = scsi_host_next_hn++; /* XXX(hch): still racy */
	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->cmd_per_lun = sht->cmd_per_lun;
	shost->unchecked_isa_dma = sht->unchecked_isa_dma;
	shost->use_clustering = sht->use_clustering;
	shost->ordered_tag = sht->ordered_tag;
	shost->active_mode = sht->supported_mode;
	shost->use_sg_chaining = sht->use_sg_chaining;

	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;

	/*
	* assume a 4GB boundary, if not set
	*/
	if (sht->dma_boundary)
	shost->dma_boundary = sht->dma_boundary;
	else
	shost->dma_boundary = 0xffffffff;

	rval = scsi_setup_command_freelist(shost);
	if (rval)
	goto fail_kfree;

	device_initialize(&shost->shost_gendev);
	snprintf(shost->shost_gendev.bus_id, BUS_ID_SIZE, "host%d",
	shost->host_no);
	shost->shost_gendev.release = scsi_host_dev_release;

	class_device_initialize(&shost->shost_classdev);
	shost->shost_classdev.dev = &shost->shost_gendev;
	shost->shost_classdev.class = &shost_class;
	snprintf(shost->shost_classdev.class_id, BUS_ID_SIZE, "host%d",
	shost->host_no);

	shost->ehandler = kthread_run(scsi_error_handler, shost,
	"scsi_eh_%d", shost->host_no);
	if (IS_ERR(shost->ehandler)) {
	rval = PTR_ERR(shost->ehandler);
	goto fail_destroy_freelist;
	}

	scsi_proc_hostdir_add(shost->hostt);
	return shost;

	fail_destroy_freelist:
	scsi_destroy_command_freelist(shost);
	fail_kfree:
	kfree(shost);
	return NULL;
	}
	EXPORT_SYMBOL(scsi_host_alloc);

	struct Scsi_Host scsi_register(struct scsi_host_template sht, int privsize)
	{
	struct Scsi_Host *shost = scsi_host_alloc(sht, privsize);

	if (!sht->detect) {
	printk(KERN_WARNING "scsi_register() called on new-style "
	"template for driver %s\n", sht->name);
	dump_stack();
	}

	if (shost)
	list_add_tail(&shost->sht_legacy_list, &sht->legacy_hosts);
	return shost;
	}
	EXPORT_SYMBOL(scsi_register);

	void scsi_unregister(struct Scsi_Host *shost)
	{
	list_del(&shost->sht_legacy_list);
	scsi_host_put(shost);
	}
	EXPORT_SYMBOL(scsi_unregister);

	static int __scsi_host_match(struct class_device cdev, void data)
	{
	struct Scsi_Host *p;
	unsigned short hostnum = (unsigned short )data;

	p = class_to_shost(cdev);
	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.
	**/
	struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
	{
	struct class_device *cdev;
	struct Scsi_Host *shost = ERR_PTR(-ENXIO);

	cdev = class_find_child(&shost_class, &hostnum, __scsi_host_match);
	if (cdev)
	shost = scsi_host_get(class_to_shost(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);

	/**
	* 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);
	}

	int scsi_is_host_device(const struct device *dev)
	{
	return dev->release == scsi_host_dev_release;
	}
	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)) {
	printk(KERN_ERR
	"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) {
	printk(KERN_ERR
	"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);