swh:1:snp:13806c77fd4b7f42b1e985e730bd615fd52cfac1
Tip revision: 7111951b8d4973bda27ff663f2cf18b663d15b48 authored by Linus Torvalds on 29 March 2020, 22:25:41 UTC
Linux 5.6
Linux 5.6
Tip revision: 7111951
bsg.c
// SPDX-License-Identifier: GPL-2.0
/*
* bsg.c - block layer implementation of the sg v4 interface
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/blkdev.h>
#include <linux/cdev.h>
#include <linux/jiffies.h>
#include <linux/percpu.h>
#include <linux/idr.h>
#include <linux/bsg.h>
#include <linux/slab.h>
#include <scsi/scsi.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/sg.h>
#define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
#define BSG_VERSION "0.4"
#define bsg_dbg(bd, fmt, ...) \
pr_debug("%s: " fmt, (bd)->name, ##__VA_ARGS__)
struct bsg_device {
struct request_queue *queue;
spinlock_t lock;
struct hlist_node dev_list;
refcount_t ref_count;
char name[20];
int max_queue;
};
#define BSG_DEFAULT_CMDS 64
#define BSG_MAX_DEVS 32768
static DEFINE_MUTEX(bsg_mutex);
static DEFINE_IDR(bsg_minor_idr);
#define BSG_LIST_ARRAY_SIZE 8
static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
static struct class *bsg_class;
static int bsg_major;
static inline struct hlist_head *bsg_dev_idx_hash(int index)
{
return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
}
#define uptr64(val) ((void __user *)(uintptr_t)(val))
static int bsg_scsi_check_proto(struct sg_io_v4 *hdr)
{
if (hdr->protocol != BSG_PROTOCOL_SCSI ||
hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
return -EINVAL;
return 0;
}
static int bsg_scsi_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
fmode_t mode)
{
struct scsi_request *sreq = scsi_req(rq);
if (hdr->dout_xfer_len && hdr->din_xfer_len) {
pr_warn_once("BIDI support in bsg has been removed.\n");
return -EOPNOTSUPP;
}
sreq->cmd_len = hdr->request_len;
if (sreq->cmd_len > BLK_MAX_CDB) {
sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL);
if (!sreq->cmd)
return -ENOMEM;
}
if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len))
return -EFAULT;
if (blk_verify_command(sreq->cmd, mode))
return -EPERM;
return 0;
}
static int bsg_scsi_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
{
struct scsi_request *sreq = scsi_req(rq);
int ret = 0;
/*
* fill in all the output members
*/
hdr->device_status = sreq->result & 0xff;
hdr->transport_status = host_byte(sreq->result);
hdr->driver_status = driver_byte(sreq->result);
hdr->info = 0;
if (hdr->device_status || hdr->transport_status || hdr->driver_status)
hdr->info |= SG_INFO_CHECK;
hdr->response_len = 0;
if (sreq->sense_len && hdr->response) {
int len = min_t(unsigned int, hdr->max_response_len,
sreq->sense_len);
if (copy_to_user(uptr64(hdr->response), sreq->sense, len))
ret = -EFAULT;
else
hdr->response_len = len;
}
if (rq_data_dir(rq) == READ)
hdr->din_resid = sreq->resid_len;
else
hdr->dout_resid = sreq->resid_len;
return ret;
}
static void bsg_scsi_free_rq(struct request *rq)
{
scsi_req_free_cmd(scsi_req(rq));
}
static const struct bsg_ops bsg_scsi_ops = {
.check_proto = bsg_scsi_check_proto,
.fill_hdr = bsg_scsi_fill_hdr,
.complete_rq = bsg_scsi_complete_rq,
.free_rq = bsg_scsi_free_rq,
};
static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg)
{
struct request *rq;
struct bio *bio;
struct sg_io_v4 hdr;
int ret;
if (copy_from_user(&hdr, uarg, sizeof(hdr)))
return -EFAULT;
if (!q->bsg_dev.class_dev)
return -ENXIO;
if (hdr.guard != 'Q')
return -EINVAL;
ret = q->bsg_dev.ops->check_proto(&hdr);
if (ret)
return ret;
rq = blk_get_request(q, hdr.dout_xfer_len ?
REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0);
if (IS_ERR(rq))
return PTR_ERR(rq);
ret = q->bsg_dev.ops->fill_hdr(rq, &hdr, mode);
if (ret)
return ret;
rq->timeout = msecs_to_jiffies(hdr.timeout);
if (!rq->timeout)
rq->timeout = q->sg_timeout;
if (!rq->timeout)
rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
if (rq->timeout < BLK_MIN_SG_TIMEOUT)
rq->timeout = BLK_MIN_SG_TIMEOUT;
if (hdr.dout_xfer_len) {
ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.dout_xferp),
hdr.dout_xfer_len, GFP_KERNEL);
} else if (hdr.din_xfer_len) {
ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.din_xferp),
hdr.din_xfer_len, GFP_KERNEL);
}
if (ret)
goto out_free_rq;
bio = rq->bio;
blk_execute_rq(q, NULL, rq, !(hdr.flags & BSG_FLAG_Q_AT_TAIL));
ret = rq->q->bsg_dev.ops->complete_rq(rq, &hdr);
blk_rq_unmap_user(bio);
out_free_rq:
rq->q->bsg_dev.ops->free_rq(rq);
blk_put_request(rq);
if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
return -EFAULT;
return ret;
}
static struct bsg_device *bsg_alloc_device(void)
{
struct bsg_device *bd;
bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
if (unlikely(!bd))
return NULL;
spin_lock_init(&bd->lock);
bd->max_queue = BSG_DEFAULT_CMDS;
INIT_HLIST_NODE(&bd->dev_list);
return bd;
}
static int bsg_put_device(struct bsg_device *bd)
{
struct request_queue *q = bd->queue;
mutex_lock(&bsg_mutex);
if (!refcount_dec_and_test(&bd->ref_count)) {
mutex_unlock(&bsg_mutex);
return 0;
}
hlist_del(&bd->dev_list);
mutex_unlock(&bsg_mutex);
bsg_dbg(bd, "tearing down\n");
/*
* close can always block
*/
kfree(bd);
blk_put_queue(q);
return 0;
}
static struct bsg_device *bsg_add_device(struct inode *inode,
struct request_queue *rq,
struct file *file)
{
struct bsg_device *bd;
unsigned char buf[32];
lockdep_assert_held(&bsg_mutex);
if (!blk_get_queue(rq))
return ERR_PTR(-ENXIO);
bd = bsg_alloc_device();
if (!bd) {
blk_put_queue(rq);
return ERR_PTR(-ENOMEM);
}
bd->queue = rq;
refcount_set(&bd->ref_count, 1);
hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
bsg_dbg(bd, "bound to <%s>, max queue %d\n",
format_dev_t(buf, inode->i_rdev), bd->max_queue);
return bd;
}
static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
{
struct bsg_device *bd;
lockdep_assert_held(&bsg_mutex);
hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
if (bd->queue == q) {
refcount_inc(&bd->ref_count);
goto found;
}
}
bd = NULL;
found:
return bd;
}
static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
{
struct bsg_device *bd;
struct bsg_class_device *bcd;
/*
* find the class device
*/
mutex_lock(&bsg_mutex);
bcd = idr_find(&bsg_minor_idr, iminor(inode));
if (!bcd) {
bd = ERR_PTR(-ENODEV);
goto out_unlock;
}
bd = __bsg_get_device(iminor(inode), bcd->queue);
if (!bd)
bd = bsg_add_device(inode, bcd->queue, file);
out_unlock:
mutex_unlock(&bsg_mutex);
return bd;
}
static int bsg_open(struct inode *inode, struct file *file)
{
struct bsg_device *bd;
bd = bsg_get_device(inode, file);
if (IS_ERR(bd))
return PTR_ERR(bd);
file->private_data = bd;
return 0;
}
static int bsg_release(struct inode *inode, struct file *file)
{
struct bsg_device *bd = file->private_data;
file->private_data = NULL;
return bsg_put_device(bd);
}
static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)
{
return put_user(bd->max_queue, uarg);
}
static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)
{
int queue;
if (get_user(queue, uarg))
return -EFAULT;
if (queue < 1)
return -EINVAL;
spin_lock_irq(&bd->lock);
bd->max_queue = queue;
spin_unlock_irq(&bd->lock);
return 0;
}
static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct bsg_device *bd = file->private_data;
void __user *uarg = (void __user *) arg;
switch (cmd) {
/*
* Our own ioctls
*/
case SG_GET_COMMAND_Q:
return bsg_get_command_q(bd, uarg);
case SG_SET_COMMAND_Q:
return bsg_set_command_q(bd, uarg);
/*
* SCSI/sg ioctls
*/
case SG_GET_VERSION_NUM:
case SCSI_IOCTL_GET_IDLUN:
case SCSI_IOCTL_GET_BUS_NUMBER:
case SG_SET_TIMEOUT:
case SG_GET_TIMEOUT:
case SG_GET_RESERVED_SIZE:
case SG_SET_RESERVED_SIZE:
case SG_EMULATED_HOST:
case SCSI_IOCTL_SEND_COMMAND:
return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
case SG_IO:
return bsg_sg_io(bd->queue, file->f_mode, uarg);
default:
return -ENOTTY;
}
}
static const struct file_operations bsg_fops = {
.open = bsg_open,
.release = bsg_release,
.unlocked_ioctl = bsg_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.owner = THIS_MODULE,
.llseek = default_llseek,
};
void bsg_unregister_queue(struct request_queue *q)
{
struct bsg_class_device *bcd = &q->bsg_dev;
if (!bcd->class_dev)
return;
mutex_lock(&bsg_mutex);
idr_remove(&bsg_minor_idr, bcd->minor);
if (q->kobj.sd)
sysfs_remove_link(&q->kobj, "bsg");
device_unregister(bcd->class_dev);
bcd->class_dev = NULL;
mutex_unlock(&bsg_mutex);
}
EXPORT_SYMBOL_GPL(bsg_unregister_queue);
int bsg_register_queue(struct request_queue *q, struct device *parent,
const char *name, const struct bsg_ops *ops)
{
struct bsg_class_device *bcd;
dev_t dev;
int ret;
struct device *class_dev = NULL;
/*
* we need a proper transport to send commands, not a stacked device
*/
if (!queue_is_mq(q))
return 0;
bcd = &q->bsg_dev;
memset(bcd, 0, sizeof(*bcd));
mutex_lock(&bsg_mutex);
ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
if (ret < 0) {
if (ret == -ENOSPC) {
printk(KERN_ERR "bsg: too many bsg devices\n");
ret = -EINVAL;
}
goto unlock;
}
bcd->minor = ret;
bcd->queue = q;
bcd->ops = ops;
dev = MKDEV(bsg_major, bcd->minor);
class_dev = device_create(bsg_class, parent, dev, NULL, "%s", name);
if (IS_ERR(class_dev)) {
ret = PTR_ERR(class_dev);
goto idr_remove;
}
bcd->class_dev = class_dev;
if (q->kobj.sd) {
ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
if (ret)
goto unregister_class_dev;
}
mutex_unlock(&bsg_mutex);
return 0;
unregister_class_dev:
device_unregister(class_dev);
idr_remove:
idr_remove(&bsg_minor_idr, bcd->minor);
unlock:
mutex_unlock(&bsg_mutex);
return ret;
}
int bsg_scsi_register_queue(struct request_queue *q, struct device *parent)
{
if (!blk_queue_scsi_passthrough(q)) {
WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
return -EINVAL;
}
return bsg_register_queue(q, parent, dev_name(parent), &bsg_scsi_ops);
}
EXPORT_SYMBOL_GPL(bsg_scsi_register_queue);
static struct cdev bsg_cdev;
static char *bsg_devnode(struct device *dev, umode_t *mode)
{
return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
}
static int __init bsg_init(void)
{
int ret, i;
dev_t devid;
for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
INIT_HLIST_HEAD(&bsg_device_list[i]);
bsg_class = class_create(THIS_MODULE, "bsg");
if (IS_ERR(bsg_class))
return PTR_ERR(bsg_class);
bsg_class->devnode = bsg_devnode;
ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
if (ret)
goto destroy_bsg_class;
bsg_major = MAJOR(devid);
cdev_init(&bsg_cdev, &bsg_fops);
ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
if (ret)
goto unregister_chrdev;
printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
" loaded (major %d)\n", bsg_major);
return 0;
unregister_chrdev:
unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
destroy_bsg_class:
class_destroy(bsg_class);
return ret;
}
MODULE_AUTHOR("Jens Axboe");
MODULE_DESCRIPTION(BSG_DESCRIPTION);
MODULE_LICENSE("GPL");
device_initcall(bsg_init);