diff options
Diffstat (limited to 'fs/char_dev.c')
| -rw-r--r-- | fs/char_dev.c | 150 |
1 files changed, 91 insertions, 59 deletions
diff --git a/fs/char_dev.c b/fs/char_dev.c index fb8507f521b2..c2ddb998f3c9 100644 --- a/fs/char_dev.c +++ b/fs/char_dev.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-2.0 /* * linux/fs/char_dev.c * @@ -24,10 +25,12 @@ #include "internal.h" -static struct kobj_map *cdev_map; +static struct kobj_map *cdev_map __ro_after_init; static DEFINE_MUTEX(chrdevs_lock); +#define CHRDEV_MAJOR_HASH_SIZE 255 + static struct char_device_struct { struct char_device_struct *next; unsigned int major; @@ -49,95 +52,114 @@ void chrdev_show(struct seq_file *f, off_t offset) { struct char_device_struct *cd; - if (offset < CHRDEV_MAJOR_HASH_SIZE) { - mutex_lock(&chrdevs_lock); - for (cd = chrdevs[offset]; cd; cd = cd->next) + mutex_lock(&chrdevs_lock); + for (cd = chrdevs[major_to_index(offset)]; cd; cd = cd->next) { + if (cd->major == offset) seq_printf(f, "%3d %s\n", cd->major, cd->name); - mutex_unlock(&chrdevs_lock); } + mutex_unlock(&chrdevs_lock); } #endif /* CONFIG_PROC_FS */ +static int find_dynamic_major(void) +{ + int i; + struct char_device_struct *cd; + + for (i = ARRAY_SIZE(chrdevs)-1; i >= CHRDEV_MAJOR_DYN_END; i--) { + if (chrdevs[i] == NULL) + return i; + } + + for (i = CHRDEV_MAJOR_DYN_EXT_START; + i >= CHRDEV_MAJOR_DYN_EXT_END; i--) { + for (cd = chrdevs[major_to_index(i)]; cd; cd = cd->next) + if (cd->major == i) + break; + + if (cd == NULL) + return i; + } + + return -EBUSY; +} + /* * Register a single major with a specified minor range. * - * If major == 0 this functions will dynamically allocate a major and return - * its number. - * - * If major > 0 this function will attempt to reserve the passed range of - * minors and will return zero on success. + * If major == 0 this function will dynamically allocate an unused major. + * If major > 0 this function will attempt to reserve the range of minors + * with given major. * - * Returns a -ve errno on failure. */ 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; 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); + return ERR_PTR(-EINVAL); + } + cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); if (cd == NULL) return ERR_PTR(-ENOMEM); mutex_lock(&chrdevs_lock); - /* temporary */ if (major == 0) { - for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) { - if (chrdevs[i] == NULL) - break; - } - - if (i < CHRDEV_MAJOR_DYN_END) - pr_warn("CHRDEV \"%s\" major number %d goes below the dynamic allocation range\n", - name, i); - - if (i == 0) { - ret = -EBUSY; + ret = find_dynamic_major(); + if (ret < 0) { + pr_err("CHRDEV \"%s\" dynamic allocation region is full\n", + name); goto out; } - major = i; + major = ret; } - cd->major = major; - cd->baseminor = baseminor; - cd->minorct = minorct; - strlcpy(cd->name, name, sizeof(cd->name)); - + ret = -EBUSY; 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; + } + + cd->major = major; + cd->baseminor = baseminor; + cd->minorct = minorct; + strscpy(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: @@ -328,9 +350,9 @@ static struct kobject *cdev_get(struct cdev *p) struct module *owner = p->owner; struct kobject *kobj; - if (owner && !try_module_get(owner)) + if (!try_module_get(owner)) return NULL; - kobj = kobject_get(&p->kobj); + kobj = kobject_get_unless_zero(&p->kobj); if (!kobj) module_put(owner); return kobj; @@ -461,14 +483,24 @@ int cdev_add(struct cdev *p, dev_t dev, unsigned count) p->dev = dev; p->count = count; + if (WARN_ON(dev == WHITEOUT_DEV)) { + error = -EBUSY; + goto err; + } + error = kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p); if (error) - return error; + goto err; kobject_get(p->kobj.parent); return 0; + +err: + kfree_const(p->kobj.name); + p->kobj.name = NULL; + return error; } /** @@ -522,7 +554,7 @@ int cdev_device_add(struct cdev *cdev, struct device *dev) } rc = device_add(dev); - if (rc) + if (rc && dev->devt) cdev_del(cdev); return rc; @@ -530,8 +562,8 @@ int cdev_device_add(struct cdev *cdev, struct device *dev) /** * cdev_device_del() - inverse of cdev_device_add - * @dev: the device structure * @cdev: the cdev structure + * @dev: the device structure * * cdev_device_del() is a helper function to call cdev_del and device_del. * It should be used whenever cdev_device_add is used. |