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chardev: code cleanup for __register_chrdev_region()

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It's just code cleanup, not functional change.

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Chengguang Xu 2019-02-15 20:27:13 +08:00 committed by Greg Kroah-Hartman
parent 4712d3796f
commit 4b0be57260
1 changed files with 28 additions and 41 deletions
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69
fs/char_dev.c
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@ -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);
@ -126,10 +132,20 @@ __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;
i = major_to_index(major);
for (curr = chrdevs[i]; curr; prev = curr, curr = curr->next) {
if (curr->major < major)
continue;
if (curr->major > major)
break;
if (curr->baseminor + curr->minorct <= baseminor)
continue;
if (curr->baseminor >= baseminor + minorct)
break;
goto out;
}
@ -138,43 +154,14 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
cd->minorct = minorct;
strlcpy(cd->name, name, sizeof(cd->name));
i = major_to_index(major);
for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
if ((*cp)->major > major ||
((*cp)->major == major &&
(((*cp)->baseminor >= baseminor) ||
((*cp)->baseminor + (*cp)->minorct > baseminor))))
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;
/* New driver overlaps from the left. */
if (new_max >= old_min && new_max <= old_max) {
ret = -EBUSY;
goto out;
}
/* 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;
}
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: