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Message-ID: <4A79283E.7030202@kernel.org>
Date: Wed, 05 Aug 2009 15:35:42 +0900
From: Tejun Heo <tj@...nel.org>
To: Greg KH <greg@...ah.com>, Al Viro <viro@....linux.org.uk>,
Takashi Iwai <tiwai@...e.de>,
Linux Kernel <linux-kernel@...r.kernel.org>
CC: cguthrie@...driva.org
Subject: [PATCH 1/2] chrdev: implement __[un]register_chrdev()
[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@...nel.org>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Greg Kroah-Hartman <gregkh@...e.de>
---
Hello,
These two patches make sound_core grabbing OSS device number optional.
If there's no objection, I think it would be easiest to push this
through Takashi's tree.
Thanks.
fs/char_dev.c | 63 +++++++++++++++++++++++++++++++++++++++++++----------
include/linux/fs.h | 11 ++++++---
2 files changed, 60 insertions(+), 14 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;
@@ -290,11 +290,26 @@ 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;
}
/**
+ * register_chrdev() - create and register a cdev occupying a full major
+ * @major: major device number or 0 for dynamic allocation
+ * @name: name of this range of devices
+ * @fops: file operations associated with this devices
+ *
+ * Wrapper around __register_chrdev() which always allocates full
+ * minor range from 0 to 256.
+ */
+int register_chrdev(unsigned int major, const char *name,
+ const struct file_operations *fops)
+{
+ return __register_chrdev(major, 0, 256, name, fops);
+}
+
+/**
* unregister_chrdev_region() - return a range of device numbers
* @from: the first in the range of numbers to unregister
* @count: the number of device numbers to unregister
@@ -316,15 +331,41 @@ 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);
}
+/**
+ * unregister_chrdev - unregister and destroy a cdev
+ * @major: major device number
+ * @name: name of this range of devices
+ *
+ * Wrapper around __unregister_chrdev() which assumes full minor range
+ * from 0 to 256.
+ */
+void unregister_chrdev(unsigned int major, const char *name)
+{
+ __unregister_chrdev(major, 0, 256, name);
+}
+
static DEFINE_SPINLOCK(cdev_lock);
static struct kobject *cdev_get(struct cdev *p)
Index: work/include/linux/fs.h
===================================================================
--- work.orig/include/linux/fs.h
+++ work/include/linux/fs.h
@@ -1998,9 +1998,14 @@ 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 int register_chrdev(unsigned int major, 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(unsigned int major, const char *name);
extern void unregister_chrdev_region(dev_t, unsigned);
extern void chrdev_show(struct seq_file *,off_t);
--
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