diff options
Diffstat (limited to 'fs/char_dev.c')
| -rw-r--r-- | fs/char_dev.c | 88 |
1 files changed, 83 insertions, 5 deletions
diff --git a/fs/char_dev.c b/fs/char_dev.c index 0009346d827f..a885f46ca001 100644 --- a/fs/char_dev.c +++ b/fs/char_dev.c @@ -24,6 +24,7 @@ #ifdef CONFIG_KMOD #include <linux/kmod.h> #endif +#include "internal.h" /* * capabilities for /dev/mem, /dev/kmem and similar directly mappable character @@ -128,13 +129,31 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor, for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) if ((*cp)->major > major || - ((*cp)->major == major && (*cp)->baseminor >= baseminor)) + ((*cp)->major == major && + (((*cp)->baseminor >= baseminor) || + ((*cp)->baseminor + (*cp)->minorct > baseminor)))) break; - if (*cp && (*cp)->major == major && - (*cp)->baseminor < baseminor + minorct) { - ret = -EBUSY; - goto out; + + /* 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; + } } + cd->next = *cp; *cp = cd; mutex_unlock(&chrdevs_lock); @@ -165,6 +184,15 @@ __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) return cd; } +/** + * register_chrdev_region() - register a range of device numbers + * @from: the first in the desired range of device numbers; must include + * the major number. + * @count: the number of consecutive device numbers required + * @name: the name of the device or driver. + * + * Return value is zero on success, a negative error code on failure. + */ int register_chrdev_region(dev_t from, unsigned count, const char *name) { struct char_device_struct *cd; @@ -190,6 +218,17 @@ fail: return PTR_ERR(cd); } +/** + * alloc_chrdev_region() - register a range of char device numbers + * @dev: output parameter for first assigned number + * @baseminor: first of the requested range of minor numbers + * @count: the number of minor numbers required + * @name: the name of the associated device or driver + * + * Allocates a range of char device numbers. The major number will be + * chosen dynamically, and returned (along with the first minor number) + * in @dev. Returns zero or a negative error code. + */ int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, const char *name) { @@ -259,6 +298,15 @@ out2: return err; } +/** + * 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 + * + * This function will unregister a range of @count device numbers, + * starting with @from. The caller should normally be the one who + * allocated those numbers in the first place... + */ void unregister_chrdev_region(dev_t from, unsigned count) { dev_t to = from + count; @@ -396,6 +444,16 @@ static int exact_lock(dev_t dev, void *data) return cdev_get(p) ? 0 : -1; } +/** + * cdev_add() - add a char device to the system + * @p: the cdev structure for the device + * @dev: the first device number for which this device is responsible + * @count: the number of consecutive minor numbers corresponding to this + * device + * + * cdev_add() adds the device represented by @p to the system, making it + * live immediately. A negative error code is returned on failure. + */ int cdev_add(struct cdev *p, dev_t dev, unsigned count) { p->dev = dev; @@ -408,6 +466,13 @@ static void cdev_unmap(dev_t dev, unsigned count) kobj_unmap(cdev_map, dev, count); } +/** + * cdev_del() - remove a cdev from the system + * @p: the cdev structure to be removed + * + * cdev_del() removes @p from the system, possibly freeing the structure + * itself. + */ void cdev_del(struct cdev *p) { cdev_unmap(p->dev, p->count); @@ -436,6 +501,11 @@ static struct kobj_type ktype_cdev_dynamic = { .release = cdev_dynamic_release, }; +/** + * cdev_alloc() - allocate a cdev structure + * + * Allocates and returns a cdev structure, or NULL on failure. + */ struct cdev *cdev_alloc(void) { struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); @@ -447,6 +517,14 @@ struct cdev *cdev_alloc(void) return p; } +/** + * cdev_init() - initialize a cdev structure + * @cdev: the structure to initialize + * @fops: the file_operations for this device + * + * Initializes @cdev, remembering @fops, making it ready to add to the + * system with cdev_add(). + */ void cdev_init(struct cdev *cdev, const struct file_operations *fops) { memset(cdev, 0, sizeof *cdev); |