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chrdev: implement __[un]register_chrdev()

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[un]register_chrdev() assume minor range 0-255.  This patch adds __
prefixed versions which take @minorbase and @count explicitly.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Tejun Heo 2009-08-06 18:13:23 +09:00 committed by Takashi Iwai
parent ed680c4ad4
commit 1905b1bfc0
2 changed files with 42 additions and 16 deletions
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39
fs/char_dev.c
View File

@ -237,8 +237,10 @@ int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
}
/**
* register_chrdev() - Register a major number for character devices.
* __register_chrdev() - create and register a cdev occupying a range of minors
* @major: major device number or 0 for dynamic allocation
* @baseminor: first of the requested range of minor numbers
* @count: the number of minor numbers required
* @name: name of this range of devices
* @fops: file operations associated with this devices
*
@ -254,19 +256,17 @@ int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
* /dev. It only helps to keep track of the different owners of devices. If
* your module name has only one type of devices it's ok to use e.g. the name
* of the module here.
*
* This function registers a range of 256 minor numbers. The first minor number
* is 0.
*/
int register_chrdev(unsigned int major, const char *name,
const struct file_operations *fops)
int __register_chrdev(unsigned int major, unsigned int baseminor,
unsigned int count, const char *name,
const struct file_operations *fops)
{
struct char_device_struct *cd;
struct cdev *cdev;
char *s;
int err = -ENOMEM;
cd = __register_chrdev_region(major, 0, 256, name);
cd = __register_chrdev_region(major, baseminor, count, name);
if (IS_ERR(cd))
return PTR_ERR(cd);
@ -280,7 +280,7 @@ int register_chrdev(unsigned int major, const char *name,
for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
*s = '!';
err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
err = cdev_add(cdev, MKDEV(cd->major, baseminor), count);
if (err)
goto out;
@ -290,7 +290,7 @@ int register_chrdev(unsigned int major, const char *name,
out:
kobject_put(&cdev->kobj);
out2:
kfree(__unregister_chrdev_region(cd->major, 0, 256));
kfree(__unregister_chrdev_region(cd->major, baseminor, count));
return err;
}
@ -316,10 +316,23 @@ void unregister_chrdev_region(dev_t from, unsigned count)
}
}
void unregister_chrdev(unsigned int major, const char *name)
/**
* __unregister_chrdev - unregister and destroy a cdev
* @major: major device number
* @baseminor: first of the range of minor numbers
* @count: the number of minor numbers this cdev is occupying
* @name: name of this range of devices
*
* Unregister and destroy the cdev occupying the region described by
* @major, @baseminor and @count. This function undoes what
* __register_chrdev() did.
*/
void __unregister_chrdev(unsigned int major, unsigned int baseminor,
unsigned int count, const char *name)
{
struct char_device_struct *cd;
cd = __unregister_chrdev_region(major, 0, 256);
cd = __unregister_chrdev_region(major, baseminor, count);
if (cd && cd->cdev)
cdev_del(cd->cdev);
kfree(cd);
@ -568,6 +581,6 @@ EXPORT_SYMBOL(cdev_alloc);
EXPORT_SYMBOL(cdev_del);
EXPORT_SYMBOL(cdev_add);
EXPORT_SYMBOL(cdev_index);
EXPORT_SYMBOL(register_chrdev);
EXPORT_SYMBOL(unregister_chrdev);
EXPORT_SYMBOL(__register_chrdev);
EXPORT_SYMBOL(__unregister_chrdev);
EXPORT_SYMBOL(directly_mappable_cdev_bdi);

19
include/linux/fs.h
View File

@ -1998,12 +1998,25 @@ extern void bd_release_from_disk(struct block_device *, struct gendisk *);
#define CHRDEV_MAJOR_HASH_SIZE 255
extern int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *);
extern int register_chrdev_region(dev_t, unsigned, const char *);
extern int register_chrdev(unsigned int, const char *,
const struct file_operations *);
extern void unregister_chrdev(unsigned int, const char *);
extern int __register_chrdev(unsigned int major, unsigned int baseminor,
unsigned int count, const char *name,
const struct file_operations *fops);
extern void __unregister_chrdev(unsigned int major, unsigned int baseminor,
unsigned int count, const char *name);
extern void unregister_chrdev_region(dev_t, unsigned);
extern void chrdev_show(struct seq_file *,off_t);
static inline int register_chrdev(unsigned int major, const char *name,
const struct file_operations *fops)
{
return __register_chrdev(major, 0, 256, name, fops);
}
static inline void unregister_chrdev(unsigned int major, const char *name)
{
__unregister_chrdev(major, 0, 256, name);
}
/* fs/block_dev.c */
#define BDEVNAME_SIZE 32 /* Largest string for a blockdev identifier */
#define BDEVT_SIZE 10 /* Largest string for MAJ:MIN for blkdev */