diff options
| -rw-r--r-- | fs/char_dev.c | 69 |
1 files changed, 28 insertions, 41 deletions
diff --git a/fs/char_dev.c b/fs/char_dev.c index 6803e98414f1..bd2bf1fd847e 100644 --- a/fs/char_dev.c +++ b/fs/char_dev.c @@ -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; - } + 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: |