Re: [PATCH 1/3] chrdev: implement __[un]register_chrdev()

[Takashi Iwai <tiwai@suse.de>]

At Thu, 06 Aug 2009 18:13:23 +0900,
Tejun Heo wrote:
> 
> [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>
> ---
> This is updated repost of the make-OSS-device-number-claiming-optional
> patchset.
> 
>  http://thread.gmane.org/gmane.linux.kernel/873475
> 
> Changes from the last take are...
> 
> * soundcore now emits standard chrdev module aliases too.
> 
> * The sound-slot/service-* module aliases are now scheduled to be
>   removed in a year along with the config and kernel parameter to
>   disable it.
> 
> * sound_insert_unit() updated to deal with minors claimed by others at
>   chrdev layer.

I merged this to sound-unstable tree now to check the builds.
I'm going to move it to the sound tree for linux-next in tomorrow or
later.

If anybody still sees the problem with this patch set, please let me
know.


Thanks!

Takashi


> 
> Thanks.
> 
>  fs/char_dev.c      |   39 ++++++++++++++++++++++++++-------------
>  include/linux/fs.h |   19 ++++++++++++++++---
>  2 files changed, 42 insertions(+), 16 deletions(-)
> 
> Index: work/fs/char_dev.c
> ===================================================================
> --- work.orig/fs/char_dev.c
> +++ work/fs/char_dev.c
> @@ -237,8 +237,10 @@ int alloc_chrdev_region(dev_t *dev, unsi
>  }
> 
>  /**
> - * 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, unsi
>   * /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,
>  	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,
>  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
>  	}
>  }
> 
> -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);
> Index: work/include/linux/fs.h
> ===================================================================
> --- work.orig/include/linux/fs.h
> +++ work/include/linux/fs.h
> @@ -1998,12 +1998,25 @@ extern void bd_release_from_disk(struct
>  #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 */
>