v4.19.13 snapshot.
diff --git a/drivers/scsi/scsi_proc.c b/drivers/scsi/scsi_proc.c
new file mode 100644
index 0000000..7f0ceb6
--- /dev/null
+++ b/drivers/scsi/scsi_proc.c
@@ -0,0 +1,483 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/proc_fs.h>
+#include <linux/errno.h>
+#include <linux/blkdev.h>
+#include <linux/seq_file.h>
+#include <linux/mutex.h>
+#include <linux/gfp.h>
+#include <linux/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);
+
+static ssize_t proc_scsi_host_write(struct file *file, const char __user *buf,
+                           size_t count, loff_t *ppos)
+{
+	struct Scsi_Host *shost = PDE_DATA(file_inode(file));
+	ssize_t ret = -ENOMEM;
+	char *page;
+    
+	if (count > PROC_BLOCK_SIZE)
+		return -EOVERFLOW;
+
+	if (!shost->hostt->write_info)
+		return -EINVAL;
+
+	page = (char *)__get_free_page(GFP_KERNEL);
+	if (page) {
+		ret = -EFAULT;
+		if (copy_from_user(page, buf, count))
+			goto out;
+		ret = shost->hostt->write_info(shost, page, count);
+	}
+out:
+	free_page((unsigned long)page);
+	return ret;
+}
+
+static int proc_scsi_show(struct seq_file *m, void *v)
+{
+	struct Scsi_Host *shost = m->private;
+	return shost->hostt->show_info(m, shost);
+}
+
+static int proc_scsi_host_open(struct inode *inode, struct file *file)
+{
+	return single_open_size(file, proc_scsi_show, PDE_DATA(inode),
+				4 * PAGE_SIZE);
+}
+
+static const struct file_operations proc_scsi_fops = {
+	.open = proc_scsi_host_open,
+	.release = single_release,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.write = proc_scsi_host_write
+};
+
+/**
+ * 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->show_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);
+	}
+	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->show_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 = proc_create_data(name, S_IRUGO | S_IWUSR,
+		sht->proc_dir, &proc_scsi_fops, shost);
+	if (!p)
+		printk(KERN_ERR "%s: Failed to register host %d in"
+		       "%s\n", __func__, shost->host_no,
+		       sht->proc_name);
+}
+
+/**
+ * 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: %02llu\n  Vendor: ",
+		sdev->host->host_no, sdev->channel, sdev->id, sdev->lun);
+	for (i = 0; i < 8; i++) {
+		if (sdev->vendor[i] >= 0x20)
+			seq_putc(s, sdev->vendor[i]);
+		else
+			seq_putc(s, ' ');
+	}
+
+	seq_puts(s, " Model: ");
+	for (i = 0; i < 16; i++) {
+		if (sdev->model[i] >= 0x20)
+			seq_putc(s, sdev->model[i]);
+		else
+			seq_putc(s, ' ');
+	}
+
+	seq_puts(s, " Rev: ");
+	for (i = 0; i < 4; i++) {
+		if (sdev->rev[i] >= 0x20)
+			seq_putc(s, sdev->rev[i]);
+		else
+			seq_putc(s, ' ');
+	}
+
+	seq_putc(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_puts(s, " CCS\n");
+	else
+		seq_putc(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 (!shost)
+		return error;
+
+	if (shost->transportt->user_scan)
+		error = shost->transportt->user_scan(shost, channel, id, lun);
+	else
+		error = scsi_scan_host_selected(shost, channel, id, lun,
+						SCSI_SCAN_MANUAL);
+	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 (!shost)
+		return error;
+	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;
+}
+
+static int always_match(struct device *dev, void *data)
+{
+	return 1;
+}
+
+static inline struct device *next_scsi_device(struct device *start)
+{
+	struct device *next = bus_find_device(&scsi_bus_type, start, NULL,
+					      always_match);
+	put_device(start);
+	return next;
+}
+
+static void *scsi_seq_start(struct seq_file *sfile, loff_t *pos)
+{
+	struct device *dev = NULL;
+	loff_t n = *pos;
+
+	while ((dev = next_scsi_device(dev))) {
+		if (!n--)
+			break;
+		sfile->private++;
+	}
+	return dev;
+}
+
+static void *scsi_seq_next(struct seq_file *sfile, void *v, loff_t *pos)
+{
+	(*pos)++;
+	sfile->private++;
+	return next_scsi_device(v);
+}
+
+static void scsi_seq_stop(struct seq_file *sfile, void *v)
+{
+	put_device(v);
+}
+
+static int scsi_seq_show(struct seq_file *sfile, void *dev)
+{
+	if (!sfile->private)
+		seq_puts(sfile, "Attached devices:\n");
+
+	return proc_print_scsidevice(dev, sfile);
+}
+
+static const struct seq_operations scsi_seq_ops = {
+	.start	= scsi_seq_start,
+	.next	= scsi_seq_next,
+	.stop	= scsi_seq_stop,
+	.show	= scsi_seq_show
+};
+
+/**
+ * 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 seq_open(file, &scsi_seq_ops);
+}
+
+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	= seq_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);
+}