linux/block/bsg.c
Linus Torvalds 71a7507afb Driver Core changes for 6.2-rc1
Here is the set of driver core and kernfs changes for 6.2-rc1.
 
 The "big" change in here is the addition of a new macro,
 container_of_const() that will preserve the "const-ness" of a pointer
 passed into it.
 
 The "problem" of the current container_of() macro is that if you pass in
 a "const *", out of it can comes a non-const pointer unless you
 specifically ask for it.  For many usages, we want to preserve the
 "const" attribute by using the same call.  For a specific example, this
 series changes the kobj_to_dev() macro to use it, allowing it to be used
 no matter what the const value is.  This prevents every subsystem from
 having to declare 2 different individual macros (i.e.
 kobj_const_to_dev() and kobj_to_dev()) and having the compiler enforce
 the const value at build time, which having 2 macros would not do
 either.
 
 The driver for all of this have been discussions with the Rust kernel
 developers as to how to properly mark driver core, and kobject, objects
 as being "non-mutable".  The changes to the kobject and driver core in
 this pull request are the result of that, as there are lots of paths
 where kobjects and device pointers are not modified at all, so marking
 them as "const" allows the compiler to enforce this.
 
 So, a nice side affect of the Rust development effort has been already
 to clean up the driver core code to be more obvious about object rules.
 
 All of this has been bike-shedded in quite a lot of detail on lkml with
 different names and implementations resulting in the tiny version we
 have in here, much better than my original proposal.  Lots of subsystem
 maintainers have acked the changes as well.
 
 Other than this change, included in here are smaller stuff like:
   - kernfs fixes and updates to handle lock contention better
   - vmlinux.lds.h fixes and updates
   - sysfs and debugfs documentation updates
   - device property updates
 
 All of these have been in the linux-next tree for quite a while with no
 problems, OTHER than some merge issues with other trees that should be
 obvious when you hit them (block tree deletes a driver that this tree
 modifies, iommufd tree modifies code that this tree also touches).  If
 there are merge problems with these trees, please let me know.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the set of driver core and kernfs changes for 6.2-rc1.

  The "big" change in here is the addition of a new macro,
  container_of_const() that will preserve the "const-ness" of a pointer
  passed into it.

  The "problem" of the current container_of() macro is that if you pass
  in a "const *", out of it can comes a non-const pointer unless you
  specifically ask for it. For many usages, we want to preserve the
  "const" attribute by using the same call. For a specific example, this
  series changes the kobj_to_dev() macro to use it, allowing it to be
  used no matter what the const value is. This prevents every subsystem
  from having to declare 2 different individual macros (i.e.
  kobj_const_to_dev() and kobj_to_dev()) and having the compiler enforce
  the const value at build time, which having 2 macros would not do
  either.

  The driver for all of this have been discussions with the Rust kernel
  developers as to how to properly mark driver core, and kobject,
  objects as being "non-mutable". The changes to the kobject and driver
  core in this pull request are the result of that, as there are lots of
  paths where kobjects and device pointers are not modified at all, so
  marking them as "const" allows the compiler to enforce this.

  So, a nice side affect of the Rust development effort has been already
  to clean up the driver core code to be more obvious about object
  rules.

  All of this has been bike-shedded in quite a lot of detail on lkml
  with different names and implementations resulting in the tiny version
  we have in here, much better than my original proposal. Lots of
  subsystem maintainers have acked the changes as well.

  Other than this change, included in here are smaller stuff like:

   - kernfs fixes and updates to handle lock contention better

   - vmlinux.lds.h fixes and updates

   - sysfs and debugfs documentation updates

   - device property updates

  All of these have been in the linux-next tree for quite a while with
  no problems"

* tag 'driver-core-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (58 commits)
  device property: Fix documentation for fwnode_get_next_parent()
  firmware_loader: fix up to_fw_sysfs() to preserve const
  usb.h: take advantage of container_of_const()
  device.h: move kobj_to_dev() to use container_of_const()
  container_of: add container_of_const() that preserves const-ness of the pointer
  driver core: fix up missed drivers/s390/char/hmcdrv_dev.c class.devnode() conversion.
  driver core: fix up missed scsi/cxlflash class.devnode() conversion.
  driver core: fix up some missing class.devnode() conversions.
  driver core: make struct class.devnode() take a const *
  driver core: make struct class.dev_uevent() take a const *
  cacheinfo: Remove of_node_put() for fw_token
  device property: Add a blank line in Kconfig of tests
  device property: Rename goto label to be more precise
  device property: Move PROPERTY_ENTRY_BOOL() a bit down
  device property: Get rid of __PROPERTY_ENTRY_ARRAY_EL*SIZE*()
  kernfs: fix all kernel-doc warnings and multiple typos
  driver core: pass a const * into of_device_uevent()
  kobject: kset_uevent_ops: make name() callback take a const *
  kobject: kset_uevent_ops: make filter() callback take a const *
  kobject: make kobject_namespace take a const *
  ...
2022-12-16 03:54:54 -08:00

272 lines
6.2 KiB
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/sg.h>
#define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
#define BSG_VERSION "0.4"
struct bsg_device {
struct request_queue *queue;
struct device device;
struct cdev cdev;
int max_queue;
unsigned int timeout;
unsigned int reserved_size;
bsg_sg_io_fn *sg_io_fn;
};
static inline struct bsg_device *to_bsg_device(struct inode *inode)
{
return container_of(inode->i_cdev, struct bsg_device, cdev);
}
#define BSG_DEFAULT_CMDS 64
#define BSG_MAX_DEVS 32768
static DEFINE_IDA(bsg_minor_ida);
static struct class *bsg_class;
static int bsg_major;
static unsigned int bsg_timeout(struct bsg_device *bd, struct sg_io_v4 *hdr)
{
unsigned int timeout = BLK_DEFAULT_SG_TIMEOUT;
if (hdr->timeout)
timeout = msecs_to_jiffies(hdr->timeout);
else if (bd->timeout)
timeout = bd->timeout;
return max_t(unsigned int, timeout, BLK_MIN_SG_TIMEOUT);
}
static int bsg_sg_io(struct bsg_device *bd, fmode_t mode, void __user *uarg)
{
struct sg_io_v4 hdr;
int ret;
if (copy_from_user(&hdr, uarg, sizeof(hdr)))
return -EFAULT;
if (hdr.guard != 'Q')
return -EINVAL;
ret = bd->sg_io_fn(bd->queue, &hdr, mode, bsg_timeout(bd, &hdr));
if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
return -EFAULT;
return ret;
}
static int bsg_open(struct inode *inode, struct file *file)
{
if (!blk_get_queue(to_bsg_device(inode)->queue))
return -ENXIO;
return 0;
}
static int bsg_release(struct inode *inode, struct file *file)
{
blk_put_queue(to_bsg_device(inode)->queue);
return 0;
}
static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)
{
return put_user(READ_ONCE(bd->max_queue), uarg);
}
static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)
{
int max_queue;
if (get_user(max_queue, uarg))
return -EFAULT;
if (max_queue < 1)
return -EINVAL;
WRITE_ONCE(bd->max_queue, max_queue);
return 0;
}
static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct bsg_device *bd = to_bsg_device(file_inode(file));
struct request_queue *q = bd->queue;
void __user *uarg = (void __user *) arg;
int __user *intp = uarg;
int val;
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:
return put_user(30527, intp);
case SCSI_IOCTL_GET_IDLUN:
return put_user(0, intp);
case SCSI_IOCTL_GET_BUS_NUMBER:
return put_user(0, intp);
case SG_SET_TIMEOUT:
if (get_user(val, intp))
return -EFAULT;
bd->timeout = clock_t_to_jiffies(val);
return 0;
case SG_GET_TIMEOUT:
return jiffies_to_clock_t(bd->timeout);
case SG_GET_RESERVED_SIZE:
return put_user(min(bd->reserved_size, queue_max_bytes(q)),
intp);
case SG_SET_RESERVED_SIZE:
if (get_user(val, intp))
return -EFAULT;
if (val < 0)
return -EINVAL;
bd->reserved_size =
min_t(unsigned int, val, queue_max_bytes(q));
return 0;
case SG_EMULATED_HOST:
return put_user(1, intp);
case SG_IO:
return bsg_sg_io(bd, file->f_mode, uarg);
case SCSI_IOCTL_SEND_COMMAND:
pr_warn_ratelimited("%s: calling unsupported SCSI_IOCTL_SEND_COMMAND\n",
current->comm);
return -EINVAL;
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,
};
static void bsg_device_release(struct device *dev)
{
struct bsg_device *bd = container_of(dev, struct bsg_device, device);
ida_free(&bsg_minor_ida, MINOR(bd->device.devt));
kfree(bd);
}
void bsg_unregister_queue(struct bsg_device *bd)
{
struct gendisk *disk = bd->queue->disk;
if (disk && disk->queue_kobj.sd)
sysfs_remove_link(&disk->queue_kobj, "bsg");
cdev_device_del(&bd->cdev, &bd->device);
put_device(&bd->device);
}
EXPORT_SYMBOL_GPL(bsg_unregister_queue);
struct bsg_device *bsg_register_queue(struct request_queue *q,
struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn)
{
struct bsg_device *bd;
int ret;
bd = kzalloc(sizeof(*bd), GFP_KERNEL);
if (!bd)
return ERR_PTR(-ENOMEM);
bd->max_queue = BSG_DEFAULT_CMDS;
bd->reserved_size = INT_MAX;
bd->queue = q;
bd->sg_io_fn = sg_io_fn;
ret = ida_alloc_max(&bsg_minor_ida, BSG_MAX_DEVS - 1, GFP_KERNEL);
if (ret < 0) {
if (ret == -ENOSPC)
dev_err(parent, "bsg: too many bsg devices\n");
kfree(bd);
return ERR_PTR(ret);
}
bd->device.devt = MKDEV(bsg_major, ret);
bd->device.class = bsg_class;
bd->device.parent = parent;
bd->device.release = bsg_device_release;
dev_set_name(&bd->device, "%s", name);
device_initialize(&bd->device);
cdev_init(&bd->cdev, &bsg_fops);
bd->cdev.owner = THIS_MODULE;
ret = cdev_device_add(&bd->cdev, &bd->device);
if (ret)
goto out_put_device;
if (q->disk && q->disk->queue_kobj.sd) {
ret = sysfs_create_link(&q->disk->queue_kobj, &bd->device.kobj,
"bsg");
if (ret)
goto out_device_del;
}
return bd;
out_device_del:
cdev_device_del(&bd->cdev, &bd->device);
out_put_device:
put_device(&bd->device);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(bsg_register_queue);
static char *bsg_devnode(const struct device *dev, umode_t *mode)
{
return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
}
static int __init bsg_init(void)
{
dev_t devid;
int ret;
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);
printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
" loaded (major %d)\n", bsg_major);
return 0;
destroy_bsg_class:
class_destroy(bsg_class);
return ret;
}
MODULE_AUTHOR("Jens Axboe");
MODULE_DESCRIPTION(BSG_DESCRIPTION);
MODULE_LICENSE("GPL");
device_initcall(bsg_init);