Commit 4b0be572 authored by Chengguang Xu's avatar Chengguang Xu Committed by Greg Kroah-Hartman
Browse files

chardev: code cleanup for __register_chrdev_region() 



It's just code cleanup, not functional change.

Signed-off-by: default avatarChengguang Xu <cgxu519@gmx.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4712d379

fs/char_dev.c

+28 −41
Original line number Diff line number Diff line
@@ -100,10 +100,16 @@ static struct char_device_struct * 
__register_chrdev_region(unsigned int major, unsigned int baseminor,

			   int minorct, const char *name)

{

	struct char_device_struct *cd, **cp;

	int ret = 0;

	struct char_device_struct *cd, *curr, *prev = NULL;

	int ret = -EBUSY;

	int i;



	if (major >= CHRDEV_MAJOR_MAX) {

		pr_err("CHRDEV \"%s\" major requested (%u) is greater than the maximum (%u)\n",

		       name, major, CHRDEV_MAJOR_MAX-1);

		return ERR_PTR(-EINVAL);

	}



	if (minorct > MINORMASK + 1 - baseminor) {

		pr_err("CHRDEV \"%s\" minor range requested (%u-%u) is out of range of maximum range (%u-%u) for a single major\n",

			name, baseminor, baseminor + minorct - 1, 0, MINORMASK);
@@ -126,55 +132,36 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor, 
		major = ret;

	}



	if (major >= CHRDEV_MAJOR_MAX) {

		pr_err("CHRDEV \"%s\" major requested (%u) is greater than the maximum (%u)\n",

		       name, major, CHRDEV_MAJOR_MAX-1);

		ret = -EINVAL;

		goto out;

	}



	cd->major = major;

	cd->baseminor = baseminor;

	cd->minorct = minorct;

	strlcpy(cd->name, name, sizeof(cd->name));



	i = major_to_index(major);

	for (curr = chrdevs[i]; curr; prev = curr, curr = curr->next) {

		if (curr->major < major)

			continue;



	for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)

		if ((*cp)->major > major ||

		    ((*cp)->major == major &&

		     (((*cp)->baseminor >= baseminor) ||

		      ((*cp)->baseminor + (*cp)->minorct > baseminor))))

		if (curr->major > major)

			break;



	/* Check for overlapping minor ranges.  */

	if (*cp && (*cp)->major == major) {

		int old_min = (*cp)->baseminor;

		int old_max = (*cp)->baseminor + (*cp)->minorct - 1;

		int new_min = baseminor;

		int new_max = baseminor + minorct - 1;

		if (curr->baseminor + curr->minorct <= baseminor)

			continue;



		/* New driver overlaps from the left.  */

		if (new_max >= old_min && new_max <= old_max) {

			ret = -EBUSY;

			goto out;

		}

		if (curr->baseminor >= baseminor + minorct)

			break;



		/* New driver overlaps from the right.  */

		if (new_min <= old_max && new_min >= old_min) {

			ret = -EBUSY;

		goto out;

	}



		if (new_min < old_min && new_max > old_max) {

			ret = -EBUSY;

			goto out;

		}

	cd->major = major;

	cd->baseminor = baseminor;

	cd->minorct = minorct;

	strlcpy(cd->name, name, sizeof(cd->name));



	if (!prev) {

		cd->next = curr;

		chrdevs[i] = cd;

	} else {

		cd->next = prev->next;

		prev->next = cd;

	}



	cd->next = *cp;

	*cp = cd;

	mutex_unlock(&chrdevs_lock);

	return cd;

out: