drivers/scsi/scsi_proc.c - maze/linux - Git at Google

 /*
  * linux/drivers/scsi/scsi_proc.c
  *
  * The functions in this file provide an interface between
  * the PROC file system and the SCSI device drivers
  * It is mainly used for debugging, statistics and to pass
  * information directly to the lowlevel driver.
  *
  * (c) 1995 Michael Neuffer neuffer@goofy.zdv.uni-mainz.de
  * Version: 0.99.8   last change: 95/09/13
  *
  * generic command parser provided by:
  * Andreas Heilwagen <crashcar@informatik.uni-koblenz.de>
  *
  * generic_proc_info() support of xxxx_info() by:
  * Michael A. Griffith <grif@acm.org>
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/string.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/proc_fs.h>
 #include <linux/errno.h>
 #include <linux/blkdev.h>
 #include <linux/seq_file.h>
 #include <linux/mutex.h>
 #include <asm/uaccess.h>

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

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


 /* 4K page size, but our output routines, use some slack for overruns */
 #define PROC_BLOCK_SIZE (3*1024)

 static struct proc_dir_entry *proc_scsi;

 /* Protect sht->present and sht->proc_dir */
 static DEFINE_MUTEX(global_host_template_mutex);

 /**
  * proc_scsi_read - handle read from /proc by calling host's proc_info() command
  * @buffer: passed to proc_info
  * @start: passed to proc_info
  * @offset: passed to proc_info
  * @length: passed to proc_info
  * @eof: returns whether length read was less than requested
  * @data: pointer to a &struct Scsi_Host
  */

 static int proc_scsi_read(char *buffer, char **start, off_t offset,
 			  int length, int *eof, void *data)
 {
 	struct Scsi_Host *shost = data;
 	int n;

 	n = shost->hostt->proc_info(shost, buffer, start, offset, length, 0);
 	*eof = (n < length);

 	return n;
 }

 /**
  * proc_scsi_write_proc - Handle write to /proc by calling host's proc_info()
  * @file: not used
  * @buf: source of data to write.
  * @count: number of bytes (at most PROC_BLOCK_SIZE) to write.
  * @data: pointer to &struct Scsi_Host
  */
 static int proc_scsi_write_proc(struct file *file, const char __user *buf,
                            unsigned long count, void *data)
 {
 	struct Scsi_Host *shost = data;
 	ssize_t ret = -ENOMEM;
 	char *page;
 	char *start;

 	if (count > PROC_BLOCK_SIZE)
 		return -EOVERFLOW;

 	page = (char *)__get_free_page(GFP_KERNEL);
 	if (page) {
 		ret = -EFAULT;
 		if (copy_from_user(page, buf, count))
 			goto out;
 		ret = shost->hostt->proc_info(shost, page, &start, 0, count, 1);
 	}
 out:
 	free_page((unsigned long)page);
 	return ret;
 }

 /**
  * scsi_proc_hostdir_add - Create directory in /proc for a scsi host
  * @sht: owner of this directory
  *
  * Sets sht->proc_dir to the new directory.
  */

 void scsi_proc_hostdir_add(struct scsi_host_template *sht)
 {
 	if (!sht->proc_info)
 		return;

 	mutex_lock(&global_host_template_mutex);
 	if (!sht->present++) {
 		sht->proc_dir = proc_mkdir(sht->proc_name, proc_scsi);
         	if (!sht->proc_dir)
 			printk(KERN_ERR "%s: proc_mkdir failed for %s\n",
 			       __func__, sht->proc_name);
 		else
 			sht->proc_dir->owner = sht->module;
 	}
 	mutex_unlock(&global_host_template_mutex);
 }

 /**
  * scsi_proc_hostdir_rm - remove directory in /proc for a scsi host
  * @sht: owner of directory
  */
 void scsi_proc_hostdir_rm(struct scsi_host_template *sht)
 {
 	if (!sht->proc_info)
 		return;

 	mutex_lock(&global_host_template_mutex);
 	if (!--sht->present && sht->proc_dir) {
 		remove_proc_entry(sht->proc_name, proc_scsi);
 		sht->proc_dir = NULL;
 	}
 	mutex_unlock(&global_host_template_mutex);
 }


 /**
  * scsi_proc_host_add - Add entry for this host to appropriate /proc dir
  * @shost: host to add
  */
 void scsi_proc_host_add(struct Scsi_Host *shost)
 {
 	struct scsi_host_template *sht = shost->hostt;
 	struct proc_dir_entry *p;
 	char name[10];

 	if (!sht->proc_dir)
 		return;

 	sprintf(name,"%d", shost->host_no);
 	p = create_proc_read_entry(name, S_IFREG | S_IRUGO | S_IWUSR,
 			sht->proc_dir, proc_scsi_read, shost);
 	if (!p) {
 		printk(KERN_ERR "%s: Failed to register host %d in"
 		       "%s\n", __func__, shost->host_no,
 		       sht->proc_name);
 		return;
 	}

 	p->write_proc = proc_scsi_write_proc;
 	p->owner = sht->module;
 }

 /**
  * scsi_proc_host_rm - remove this host's entry from /proc
  * @shost: which host
  */
 void scsi_proc_host_rm(struct Scsi_Host *shost)
 {
 	char name[10];

 	if (!shost->hostt->proc_dir)
 		return;

 	sprintf(name,"%d", shost->host_no);
 	remove_proc_entry(name, shost->hostt->proc_dir);
 }
 /**
  * proc_print_scsidevice - return data about this host
  * @dev: A scsi device
  * @data: &struct seq_file to output to.
  *
  * Description: prints Host, Channel, Id, Lun, Vendor, Model, Rev, Type,
  * and revision.
  */
 static int proc_print_scsidevice(struct device *dev, void *data)
 {
 	struct scsi_device *sdev;
 	struct seq_file *s = data;
 	int i;

 	if (!scsi_is_sdev_device(dev))
 		goto out;

 	sdev = to_scsi_device(dev);
 	seq_printf(s,
 		"Host: scsi%d Channel: %02d Id: %02d Lun: %02d\n  Vendor: ",
 		sdev->host->host_no, sdev->channel, sdev->id, sdev->lun);
 	for (i = 0; i < 8; i++) {
 		if (sdev->vendor[i] >= 0x20)
 			seq_printf(s, "%c", sdev->vendor[i]);
 		else
 			seq_printf(s, " ");
 	}

 	seq_printf(s, " Model: ");
 	for (i = 0; i < 16; i++) {
 		if (sdev->model[i] >= 0x20)
 			seq_printf(s, "%c", sdev->model[i]);
 		else
 			seq_printf(s, " ");
 	}

 	seq_printf(s, " Rev: ");
 	for (i = 0; i < 4; i++) {
 		if (sdev->rev[i] >= 0x20)
 			seq_printf(s, "%c", sdev->rev[i]);
 		else
 			seq_printf(s, " ");
 	}

 	seq_printf(s, "\n");

 	seq_printf(s, "  Type:   %s ", scsi_device_type(sdev->type));
 	seq_printf(s, "               ANSI  SCSI revision: %02x",
 			sdev->scsi_level - (sdev->scsi_level > 1));
 	if (sdev->scsi_level == 2)
 		seq_printf(s, " CCS\n");
 	else
 		seq_printf(s, "\n");

 out:
 	return 0;
 }

 /**
  * scsi_add_single_device - Respond to user request to probe for/add device
  * @host: user-supplied decimal integer
  * @channel: user-supplied decimal integer
  * @id: user-supplied decimal integer
  * @lun: user-supplied decimal integer
  *
  * Description: called by writing "scsi add-single-device" to /proc/scsi/scsi.
  *
  * does scsi_host_lookup() and either user_scan() if that transport
  * type supports it, or else scsi_scan_host_selected()
  *
  * Note: this seems to be aimed exclusively at SCSI parallel busses.
  */

 static int scsi_add_single_device(uint host, uint channel, uint id, uint lun)
 {
 	struct Scsi_Host *shost;
 	int error = -ENXIO;

 	shost = scsi_host_lookup(host);
 	if (IS_ERR(shost))
 		return PTR_ERR(shost);

 	if (shost->transportt->user_scan)
 		error = shost->transportt->user_scan(shost, channel, id, lun);
 	else
 		error = scsi_scan_host_selected(shost, channel, id, lun, 1);
 	scsi_host_put(shost);
 	return error;
 }

 /**
  * scsi_remove_single_device - Respond to user request to remove a device
  * @host: user-supplied decimal integer
  * @channel: user-supplied decimal integer
  * @id: user-supplied decimal integer
  * @lun: user-supplied decimal integer
  *
  * Description: called by writing "scsi remove-single-device" to
  * /proc/scsi/scsi.  Does a scsi_device_lookup() and scsi_remove_device()
  */
 static int scsi_remove_single_device(uint host, uint channel, uint id, uint lun)
 {
 	struct scsi_device *sdev;
 	struct Scsi_Host *shost;
 	int error = -ENXIO;

 	shost = scsi_host_lookup(host);
 	if (IS_ERR(shost))
 		return PTR_ERR(shost);
 	sdev = scsi_device_lookup(shost, channel, id, lun);
 	if (sdev) {
 		scsi_remove_device(sdev);
 		scsi_device_put(sdev);
 		error = 0;
 	}

 	scsi_host_put(shost);
 	return error;
 }

 /**
  * proc_scsi_write - handle writes to /proc/scsi/scsi
  * @file: not used
  * @buf: buffer to write
  * @length: length of buf, at most PAGE_SIZE
  * @ppos: not used
  *
  * Description: this provides a legacy mechanism to add or remove devices by
  * Host, Channel, ID, and Lun.  To use,
  * "echo 'scsi add-single-device 0 1 2 3' > /proc/scsi/scsi" or
  * "echo 'scsi remove-single-device 0 1 2 3' > /proc/scsi/scsi" with
  * "0 1 2 3" replaced by the Host, Channel, Id, and Lun.
  *
  * Note: this seems to be aimed at parallel SCSI. Most modern busses (USB,
  * SATA, Firewire, Fibre Channel, etc) dynamically assign these values to
  * provide a unique identifier and nothing more.
  */


 static ssize_t proc_scsi_write(struct file *file, const char __user *buf,
 			       size_t length, loff_t *ppos)
 {
 	int host, channel, id, lun;
 	char *buffer, *p;
 	int err;

 	if (!buf || length > PAGE_SIZE)
 		return -EINVAL;

 	buffer = (char *)__get_free_page(GFP_KERNEL);
 	if (!buffer)
 		return -ENOMEM;

 	err = -EFAULT;
 	if (copy_from_user(buffer, buf, length))
 		goto out;

 	err = -EINVAL;
 	if (length < PAGE_SIZE)
 		buffer[length] = '\0';
 	else if (buffer[PAGE_SIZE-1])
 		goto out;

 	/*
 	 * Usage: echo "scsi add-single-device 0 1 2 3" >/proc/scsi/scsi
 	 * with  "0 1 2 3" replaced by your "Host Channel Id Lun".
 	 */
 	if (!strncmp("scsi add-single-device", buffer, 22)) {
 		p = buffer + 23;

 		host = simple_strtoul(p, &p, 0);
 		channel = simple_strtoul(p + 1, &p, 0);
 		id = simple_strtoul(p + 1, &p, 0);
 		lun = simple_strtoul(p + 1, &p, 0);

 		err = scsi_add_single_device(host, channel, id, lun);

 	/*
 	 * Usage: echo "scsi remove-single-device 0 1 2 3" >/proc/scsi/scsi
 	 * with  "0 1 2 3" replaced by your "Host Channel Id Lun".
 	 */
 	} else if (!strncmp("scsi remove-single-device", buffer, 25)) {
 		p = buffer + 26;

 		host = simple_strtoul(p, &p, 0);
 		channel = simple_strtoul(p + 1, &p, 0);
 		id = simple_strtoul(p + 1, &p, 0);
 		lun = simple_strtoul(p + 1, &p, 0);

 		err = scsi_remove_single_device(host, channel, id, lun);
 	}

 	/*
 	 * convert success returns so that we return the
 	 * number of bytes consumed.
 	 */
 	if (!err)
 		err = length;

  out:
 	free_page((unsigned long)buffer);
 	return err;
 }

 /**
  * proc_scsi_show - show contents of /proc/scsi/scsi (attached devices)
  * @s: output goes here
  * @p: not used
  */
 static int proc_scsi_show(struct seq_file *s, void *p)
 {
 	seq_printf(s, "Attached devices:\n");
 	bus_for_each_dev(&scsi_bus_type, NULL, s, proc_print_scsidevice);
 	return 0;
 }

 /**
  * proc_scsi_open - glue function
  * @inode: not used
  * @file: passed to single_open()
  *
  * Associates proc_scsi_show with this file
  */
 static int proc_scsi_open(struct inode *inode, struct file *file)
 {
 	/*
 	 * We don't really need this for the write case but it doesn't
 	 * harm either.
 	 */
 	return single_open(file, proc_scsi_show, NULL);
 }

 static const struct file_operations proc_scsi_operations = {
 	.owner		= THIS_MODULE,
 	.open		= proc_scsi_open,
 	.read		= seq_read,
 	.write		= proc_scsi_write,
 	.llseek		= seq_lseek,
 	.release	= single_release,
 };

 /**
  * scsi_init_procfs - create scsi and scsi/scsi in procfs
  */
 int __init scsi_init_procfs(void)
 {
 	struct proc_dir_entry *pde;

 	proc_scsi = proc_mkdir("scsi", NULL);
 	if (!proc_scsi)
 		goto err1;

 	pde = proc_create("scsi/scsi", 0, NULL, &proc_scsi_operations);
 	if (!pde)
 		goto err2;

 	return 0;

 err2:
 	remove_proc_entry("scsi", NULL);
 err1:
 	return -ENOMEM;
 }

 /**
  * scsi_exit_procfs - Remove scsi/scsi and scsi from procfs
  */
 void scsi_exit_procfs(void)
 {
 	remove_proc_entry("scsi/scsi", NULL);
 	remove_proc_entry("scsi", NULL);
 }
	/*
	* linux/drivers/scsi/scsi_proc.c
	*
	* The functions in this file provide an interface between
	* the PROC file system and the SCSI device drivers
	* It is mainly used for debugging, statistics and to pass
	* information directly to the lowlevel driver.
	*
	* (c) 1995 Michael Neuffer neuffer@goofy.zdv.uni-mainz.de
	* Version: 0.99.8 last change: 95/09/13
	*
	* generic command parser provided by:
	* Andreas Heilwagen <crashcar@informatik.uni-koblenz.de>
	*
	* generic_proc_info() support of xxxx_info() by:
	* Michael A. Griffith <grif@acm.org>
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/string.h>
	#include <linux/mm.h>
	#include <linux/slab.h>
	#include <linux/proc_fs.h>
	#include <linux/errno.h>
	#include <linux/blkdev.h>
	#include <linux/seq_file.h>
	#include <linux/mutex.h>
	#include <asm/uaccess.h>

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

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


	/* 4K page size, but our output routines, use some slack for overruns */
	#define PROC_BLOCK_SIZE (3*1024)

	static struct proc_dir_entry *proc_scsi;

	/* Protect sht->present and sht->proc_dir */
	static DEFINE_MUTEX(global_host_template_mutex);

	/**
	* proc_scsi_read - handle read from /proc by calling host's proc_info() command
	* @buffer: passed to proc_info
	* @start: passed to proc_info
	* @offset: passed to proc_info
	* @length: passed to proc_info
	* @eof: returns whether length read was less than requested
	* @data: pointer to a &struct Scsi_Host
	*/

	static int proc_scsi_read(char buffer, char *start, off_t offset,
	int length, int eof, void data)
	{
	struct Scsi_Host *shost = data;
	int n;

	n = shost->hostt->proc_info(shost, buffer, start, offset, length, 0);
	*eof = (n < length);

	return n;
	}

	/**
	* proc_scsi_write_proc - Handle write to /proc by calling host's proc_info()
	* @file: not used
	* @buf: source of data to write.
	* @count: number of bytes (at most PROC_BLOCK_SIZE) to write.
	* @data: pointer to &struct Scsi_Host
	*/
	static int proc_scsi_write_proc(struct file file, const char __user buf,
	unsigned long count, void *data)
	{
	struct Scsi_Host *shost = data;
	ssize_t ret = -ENOMEM;
	char *page;
	char *start;

	if (count > PROC_BLOCK_SIZE)
	return -EOVERFLOW;

	page = (char *)__get_free_page(GFP_KERNEL);
	if (page) {
	ret = -EFAULT;
	if (copy_from_user(page, buf, count))
	goto out;
	ret = shost->hostt->proc_info(shost, page, &start, 0, count, 1);
	}
	out:
	free_page((unsigned long)page);
	return ret;
	}

	/**
	* scsi_proc_hostdir_add - Create directory in /proc for a scsi host
	* @sht: owner of this directory
	*
	* Sets sht->proc_dir to the new directory.
	*/

	void scsi_proc_hostdir_add(struct scsi_host_template *sht)
	{
	if (!sht->proc_info)
	return;

	mutex_lock(&global_host_template_mutex);
	if (!sht->present++) {
	sht->proc_dir = proc_mkdir(sht->proc_name, proc_scsi);
	if (!sht->proc_dir)
	printk(KERN_ERR "%s: proc_mkdir failed for %s\n",
	__func__, sht->proc_name);
	else
	sht->proc_dir->owner = sht->module;
	}
	mutex_unlock(&global_host_template_mutex);
	}

	/**
	* scsi_proc_hostdir_rm - remove directory in /proc for a scsi host
	* @sht: owner of directory
	*/
	void scsi_proc_hostdir_rm(struct scsi_host_template *sht)
	{
	if (!sht->proc_info)
	return;

	mutex_lock(&global_host_template_mutex);
	if (!--sht->present && sht->proc_dir) {
	remove_proc_entry(sht->proc_name, proc_scsi);
	sht->proc_dir = NULL;
	}
	mutex_unlock(&global_host_template_mutex);
	}


	/**
	* scsi_proc_host_add - Add entry for this host to appropriate /proc dir
	* @shost: host to add
	*/
	void scsi_proc_host_add(struct Scsi_Host *shost)
	{
	struct scsi_host_template *sht = shost->hostt;
	struct proc_dir_entry *p;
	char name[10];

	if (!sht->proc_dir)
	return;

	sprintf(name,"%d", shost->host_no);
	p = create_proc_read_entry(name, S_IFREG \| S_IRUGO \| S_IWUSR,
	sht->proc_dir, proc_scsi_read, shost);
	if (!p) {
	printk(KERN_ERR "%s: Failed to register host %d in"
	"%s\n", __func__, shost->host_no,
	sht->proc_name);
	return;
	}

	p->write_proc = proc_scsi_write_proc;
	p->owner = sht->module;
	}

	/**
	* scsi_proc_host_rm - remove this host's entry from /proc
	* @shost: which host
	*/
	void scsi_proc_host_rm(struct Scsi_Host *shost)
	{
	char name[10];

	if (!shost->hostt->proc_dir)
	return;

	sprintf(name,"%d", shost->host_no);
	remove_proc_entry(name, shost->hostt->proc_dir);
	}
	/**
	* proc_print_scsidevice - return data about this host
	* @dev: A scsi device
	* @data: &struct seq_file to output to.
	*
	* Description: prints Host, Channel, Id, Lun, Vendor, Model, Rev, Type,
	* and revision.
	*/
	static int proc_print_scsidevice(struct device dev, void data)
	{
	struct scsi_device *sdev;
	struct seq_file *s = data;
	int i;

	if (!scsi_is_sdev_device(dev))
	goto out;

	sdev = to_scsi_device(dev);
	seq_printf(s,
	"Host: scsi%d Channel: %02d Id: %02d Lun: %02d\n Vendor: ",
	sdev->host->host_no, sdev->channel, sdev->id, sdev->lun);
	for (i = 0; i < 8; i++) {
	if (sdev->vendor[i] >= 0x20)
	seq_printf(s, "%c", sdev->vendor[i]);
	else
	seq_printf(s, " ");
	}

	seq_printf(s, " Model: ");
	for (i = 0; i < 16; i++) {
	if (sdev->model[i] >= 0x20)
	seq_printf(s, "%c", sdev->model[i]);
	else
	seq_printf(s, " ");
	}

	seq_printf(s, " Rev: ");
	for (i = 0; i < 4; i++) {
	if (sdev->rev[i] >= 0x20)
	seq_printf(s, "%c", sdev->rev[i]);
	else
	seq_printf(s, " ");
	}

	seq_printf(s, "\n");

	seq_printf(s, " Type: %s ", scsi_device_type(sdev->type));
	seq_printf(s, " ANSI SCSI revision: %02x",
	sdev->scsi_level - (sdev->scsi_level > 1));
	if (sdev->scsi_level == 2)
	seq_printf(s, " CCS\n");
	else
	seq_printf(s, "\n");

	out:
	return 0;
	}

	/**
	* scsi_add_single_device - Respond to user request to probe for/add device
	* @host: user-supplied decimal integer
	* @channel: user-supplied decimal integer
	* @id: user-supplied decimal integer
	* @lun: user-supplied decimal integer
	*
	* Description: called by writing "scsi add-single-device" to /proc/scsi/scsi.
	*
	* does scsi_host_lookup() and either user_scan() if that transport
	* type supports it, or else scsi_scan_host_selected()
	*
	* Note: this seems to be aimed exclusively at SCSI parallel busses.
	*/

	static int scsi_add_single_device(uint host, uint channel, uint id, uint lun)
	{
	struct Scsi_Host *shost;
	int error = -ENXIO;

	shost = scsi_host_lookup(host);
	if (IS_ERR(shost))
	return PTR_ERR(shost);

	if (shost->transportt->user_scan)
	error = shost->transportt->user_scan(shost, channel, id, lun);
	else
	error = scsi_scan_host_selected(shost, channel, id, lun, 1);
	scsi_host_put(shost);
	return error;
	}

	/**
	* scsi_remove_single_device - Respond to user request to remove a device
	* @host: user-supplied decimal integer
	* @channel: user-supplied decimal integer
	* @id: user-supplied decimal integer
	* @lun: user-supplied decimal integer
	*
	* Description: called by writing "scsi remove-single-device" to
	* /proc/scsi/scsi. Does a scsi_device_lookup() and scsi_remove_device()
	*/
	static int scsi_remove_single_device(uint host, uint channel, uint id, uint lun)
	{
	struct scsi_device *sdev;
	struct Scsi_Host *shost;
	int error = -ENXIO;

	shost = scsi_host_lookup(host);
	if (IS_ERR(shost))
	return PTR_ERR(shost);
	sdev = scsi_device_lookup(shost, channel, id, lun);
	if (sdev) {
	scsi_remove_device(sdev);
	scsi_device_put(sdev);
	error = 0;
	}

	scsi_host_put(shost);
	return error;
	}

	/**
	* proc_scsi_write - handle writes to /proc/scsi/scsi
	* @file: not used
	* @buf: buffer to write
	* @length: length of buf, at most PAGE_SIZE
	* @ppos: not used
	*
	* Description: this provides a legacy mechanism to add or remove devices by
	* Host, Channel, ID, and Lun. To use,
	* "echo 'scsi add-single-device 0 1 2 3' > /proc/scsi/scsi" or
	* "echo 'scsi remove-single-device 0 1 2 3' > /proc/scsi/scsi" with
	* "0 1 2 3" replaced by the Host, Channel, Id, and Lun.
	*
	* Note: this seems to be aimed at parallel SCSI. Most modern busses (USB,
	* SATA, Firewire, Fibre Channel, etc) dynamically assign these values to
	* provide a unique identifier and nothing more.
	*/


	static ssize_t proc_scsi_write(struct file file, const char __user buf,
	size_t length, loff_t *ppos)
	{
	int host, channel, id, lun;
	char buffer, p;
	int err;

	if (!buf \|\| length > PAGE_SIZE)
	return -EINVAL;

	buffer = (char *)__get_free_page(GFP_KERNEL);
	if (!buffer)
	return -ENOMEM;

	err = -EFAULT;
	if (copy_from_user(buffer, buf, length))
	goto out;

	err = -EINVAL;
	if (length < PAGE_SIZE)
	buffer[length] = '\0';
	else if (buffer[PAGE_SIZE-1])
	goto out;

	/*
	* Usage: echo "scsi add-single-device 0 1 2 3" >/proc/scsi/scsi
	* with "0 1 2 3" replaced by your "Host Channel Id Lun".
	*/
	if (!strncmp("scsi add-single-device", buffer, 22)) {
	p = buffer + 23;

	host = simple_strtoul(p, &p, 0);
	channel = simple_strtoul(p + 1, &p, 0);
	id = simple_strtoul(p + 1, &p, 0);
	lun = simple_strtoul(p + 1, &p, 0);

	err = scsi_add_single_device(host, channel, id, lun);

	/*
	* Usage: echo "scsi remove-single-device 0 1 2 3" >/proc/scsi/scsi
	* with "0 1 2 3" replaced by your "Host Channel Id Lun".
	*/
	} else if (!strncmp("scsi remove-single-device", buffer, 25)) {
	p = buffer + 26;

	host = simple_strtoul(p, &p, 0);
	channel = simple_strtoul(p + 1, &p, 0);
	id = simple_strtoul(p + 1, &p, 0);
	lun = simple_strtoul(p + 1, &p, 0);

	err = scsi_remove_single_device(host, channel, id, lun);
	}

	/*
	* convert success returns so that we return the
	* number of bytes consumed.
	*/
	if (!err)
	err = length;

	out:
	free_page((unsigned long)buffer);
	return err;
	}

	/**
	* proc_scsi_show - show contents of /proc/scsi/scsi (attached devices)
	* @s: output goes here
	* @p: not used
	*/
	static int proc_scsi_show(struct seq_file s, void p)
	{
	seq_printf(s, "Attached devices:\n");
	bus_for_each_dev(&scsi_bus_type, NULL, s, proc_print_scsidevice);
	return 0;
	}

	/**
	* proc_scsi_open - glue function
	* @inode: not used
	* @file: passed to single_open()
	*
	* Associates proc_scsi_show with this file
	*/
	static int proc_scsi_open(struct inode inode, struct file file)
	{
	/*
	* We don't really need this for the write case but it doesn't
	* harm either.
	*/
	return single_open(file, proc_scsi_show, NULL);
	}

	static const struct file_operations proc_scsi_operations = {
	.owner = THIS_MODULE,
	.open = proc_scsi_open,
	.read = seq_read,
	.write = proc_scsi_write,
	.llseek = seq_lseek,
	.release = single_release,
	};

	/**
	* scsi_init_procfs - create scsi and scsi/scsi in procfs
	*/
	int __init scsi_init_procfs(void)
	{
	struct proc_dir_entry *pde;

	proc_scsi = proc_mkdir("scsi", NULL);
	if (!proc_scsi)
	goto err1;

	pde = proc_create("scsi/scsi", 0, NULL, &proc_scsi_operations);
	if (!pde)
	goto err2;

	return 0;

	err2:
	remove_proc_entry("scsi", NULL);
	err1:
	return -ENOMEM;
	}

	/**
	* scsi_exit_procfs - Remove scsi/scsi and scsi from procfs
	*/
	void scsi_exit_procfs(void)
	{
	remove_proc_entry("scsi/scsi", NULL);
	remove_proc_entry("scsi", NULL);
	}