[net-next-2.6.git] / fs / char_dev.c

/*
 *  linux/fs/char_dev.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/string.h>

#include <linux/major.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/smp_lock.h>
#include <linux/seq_file.h>

#include <linux/kobject.h>
#include <linux/kobj_map.h>
#include <linux/cdev.h>
#include <linux/mutex.h>

#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif

static struct kobj_map *cdev_map;

static DEFINE_MUTEX(chrdevs_lock);

static struct char_device_struct {
	struct char_device_struct *next;
	unsigned int major;
	unsigned int baseminor;
	int minorct;
	char name[64];
	struct file_operations *fops;
	struct cdev *cdev;		/* will die */
} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];

/* index in the above */
static inline int major_to_index(int major)
{
	return major % CHRDEV_MAJOR_HASH_SIZE;
}

#ifdef CONFIG_PROC_FS

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)
			seq_printf(f, "%3d %s\n", cd->major, cd->name);
		mutex_unlock(&chrdevs_lock);
	}
}

#endif /* CONFIG_PROC_FS */

/*
 * 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.
 *
 * 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;
	int i;

	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 == 0) {
			ret = -EBUSY;
			goto out;
		}
		major = i;
		ret = major;
	}

	cd->major = major;
	cd->baseminor = baseminor;
	cd->minorct = minorct;
	strncpy(cd->name,name, 64);

	i = major_to_index(major);

	for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
		if ((*cp)->major > major ||
		    ((*cp)->major == major && (*cp)->baseminor >= baseminor))
			break;
	if (*cp && (*cp)->major == major &&
	    (*cp)->baseminor < baseminor + minorct) {
		ret = -EBUSY;
		goto out;
	}
	cd->next = *cp;
	*cp = cd;
	mutex_unlock(&chrdevs_lock);
	return cd;
out:
	mutex_unlock(&chrdevs_lock);
	kfree(cd);
	return ERR_PTR(ret);
}

static struct char_device_struct *
__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
{
	struct char_device_struct *cd = NULL, **cp;
	int i = major_to_index(major);

	mutex_lock(&chrdevs_lock);
	for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
		if ((*cp)->major == major &&
		    (*cp)->baseminor == baseminor &&
		    (*cp)->minorct == minorct)
			break;
	if (*cp) {
		cd = *cp;
		*cp = cd->next;
	}
	mutex_unlock(&chrdevs_lock);
	return cd;
}

int register_chrdev_region(dev_t from, unsigned count, const char *name)
{
	struct char_device_struct *cd;
	dev_t to = from + count;
	dev_t n, next;

	for (n = from; n < to; n = next) {
		next = MKDEV(MAJOR(n)+1, 0);
		if (next > to)
			next = to;
		cd = __register_chrdev_region(MAJOR(n), MINOR(n),
			       next - n, name);
		if (IS_ERR(cd))
			goto fail;
	}
	return 0;
fail:
	to = n;
	for (n = from; n < to; n = next) {
		next = MKDEV(MAJOR(n)+1, 0);
		kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
	}
	return PTR_ERR(cd);
}

int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
			const char *name)
{
	struct char_device_struct *cd;
	cd = __register_chrdev_region(0, baseminor, count, name);
	if (IS_ERR(cd))
		return PTR_ERR(cd);
	*dev = MKDEV(cd->major, cd->baseminor);
	return 0;
}

/**
 * register_chrdev() - Register a major number for character devices.
 * @major: major device number or 0 for dynamic allocation
 * @name: name of this range of devices
 * @fops: file operations associated with this devices
 *
 * If @major == 0 this functions will dynamically allocate a major and return
 * its number.
 *
 * If @major > 0 this function will attempt to reserve a device with the given
 * major number and will return zero on success.
 *
 * Returns a -ve errno on failure.
 *
 * The name of this device has nothing to do with the name of the device in
 * /dev. It only helps to keep track of the different owners of devices. If
 * your module name has only one type of devices it's ok to use e.g. the name
 * of the module here.
 *
 * This function registers a range of 256 minor numbers. The first minor number
 * is 0.
 */
int register_chrdev(unsigned int major, const char *name,
		    const struct file_operations *fops)
{
	struct char_device_struct *cd;
	struct cdev *cdev;
	char *s;
	int err = -ENOMEM;

	cd = __register_chrdev_region(major, 0, 256, name);
	if (IS_ERR(cd))
		return PTR_ERR(cd);
	
	cdev = cdev_alloc();
	if (!cdev)
		goto out2;

	cdev->owner = fops->owner;
	cdev->ops = fops;
	kobject_set_name(&cdev->kobj, "%s", name);
	for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
		*s = '!';
		
	err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
	if (err)
		goto out;

	cd->cdev = cdev;

	return major ? 0 : cd->major;
out:
	kobject_put(&cdev->kobj);
out2:
	kfree(__unregister_chrdev_region(cd->major, 0, 256));
	return err;
}

void unregister_chrdev_region(dev_t from, unsigned count)
{
	dev_t to = from + count;
	dev_t n, next;

	for (n = from; n < to; n = next) {
		next = MKDEV(MAJOR(n)+1, 0);
		if (next > to)
			next = to;
		kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
	}
}

int unregister_chrdev(unsigned int major, const char *name)
{
	struct char_device_struct *cd;
	cd = __unregister_chrdev_region(major, 0, 256);
	if (cd && cd->cdev)
		cdev_del(cd->cdev);
	kfree(cd);
	return 0;
}

static DEFINE_SPINLOCK(cdev_lock);

static struct kobject *cdev_get(struct cdev *p)
{
	struct module *owner = p->owner;
	struct kobject *kobj;

	if (owner && !try_module_get(owner))
		return NULL;
	kobj = kobject_get(&p->kobj);
	if (!kobj)
		module_put(owner);
	return kobj;
}

void cdev_put(struct cdev *p)
{
	if (p) {
		struct module *owner = p->owner;
		kobject_put(&p->kobj);
		module_put(owner);
	}
}

/*
 * Called every time a character special file is opened
 */
int chrdev_open(struct inode * inode, struct file * filp)
{
	struct cdev *p;
	struct cdev *new = NULL;
	int ret = 0;

	spin_lock(&cdev_lock);
	p = inode->i_cdev;
	if (!p) {
		struct kobject *kobj;
		int idx;
		spin_unlock(&cdev_lock);
		kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
		if (!kobj)
			return -ENXIO;
		new = container_of(kobj, struct cdev, kobj);
		spin_lock(&cdev_lock);
		p = inode->i_cdev;
		if (!p) {
			inode->i_cdev = p = new;
			inode->i_cindex = idx;
			list_add(&inode->i_devices, &p->list);
			new = NULL;
		} else if (!cdev_get(p))
			ret = -ENXIO;
	} else if (!cdev_get(p))
		ret = -ENXIO;
	spin_unlock(&cdev_lock);
	cdev_put(new);
	if (ret)
		return ret;
	filp->f_op = fops_get(p->ops);
	if (!filp->f_op) {
		cdev_put(p);
		return -ENXIO;
	}
	if (filp->f_op->open) {
		lock_kernel();
		ret = filp->f_op->open(inode,filp);
		unlock_kernel();
	}
	if (ret)
		cdev_put(p);
	return ret;
}

void cd_forget(struct inode *inode)
{
	spin_lock(&cdev_lock);
	list_del_init(&inode->i_devices);
	inode->i_cdev = NULL;
	spin_unlock(&cdev_lock);
}

static void cdev_purge(struct cdev *cdev)
{
	spin_lock(&cdev_lock);
	while (!list_empty(&cdev->list)) {
		struct inode *inode;
		inode = container_of(cdev->list.next, struct inode, i_devices);
		list_del_init(&inode->i_devices);
		inode->i_cdev = NULL;
	}
	spin_unlock(&cdev_lock);
}

/*
 * Dummy default file-operations: the only thing this does
 * is contain the open that then fills in the correct operations
 * depending on the special file...
 */
const struct file_operations def_chr_fops = {
	.open = chrdev_open,
};

static struct kobject *exact_match(dev_t dev, int *part, void *data)
{
	struct cdev *p = data;
	return &p->kobj;
}

static int exact_lock(dev_t dev, void *data)
{
	struct cdev *p = data;
	return cdev_get(p) ? 0 : -1;
}

int cdev_add(struct cdev *p, dev_t dev, unsigned count)
{
	p->dev = dev;
	p->count = count;
	return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
}

static void cdev_unmap(dev_t dev, unsigned count)
{
	kobj_unmap(cdev_map, dev, count);
}

void cdev_del(struct cdev *p)
{
	cdev_unmap(p->dev, p->count);
	kobject_put(&p->kobj);
}


static void cdev_default_release(struct kobject *kobj)
{
	struct cdev *p = container_of(kobj, struct cdev, kobj);
	cdev_purge(p);
}

static void cdev_dynamic_release(struct kobject *kobj)
{
	struct cdev *p = container_of(kobj, struct cdev, kobj);
	cdev_purge(p);
	kfree(p);
}

static struct kobj_type ktype_cdev_default = {
	.release	= cdev_default_release,
};

static struct kobj_type ktype_cdev_dynamic = {
	.release	= cdev_dynamic_release,
};

struct cdev *cdev_alloc(void)
{
	struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
	if (p) {
		p->kobj.ktype = &ktype_cdev_dynamic;
		INIT_LIST_HEAD(&p->list);
		kobject_init(&p->kobj);
	}
	return p;
}

void cdev_init(struct cdev *cdev, const struct file_operations *fops)
{
	memset(cdev, 0, sizeof *cdev);
	INIT_LIST_HEAD(&cdev->list);
	cdev->kobj.ktype = &ktype_cdev_default;
	kobject_init(&cdev->kobj);
	cdev->ops = fops;
}

static struct kobject *base_probe(dev_t dev, int *part, void *data)
{
	if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
		/* Make old-style 2.4 aliases work */
		request_module("char-major-%d", MAJOR(dev));
	return NULL;
}

void __init chrdev_init(void)
{
	cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
}


/* Let modules do char dev stuff */
EXPORT_SYMBOL(register_chrdev_region);
EXPORT_SYMBOL(unregister_chrdev_region);
EXPORT_SYMBOL(alloc_chrdev_region);
EXPORT_SYMBOL(cdev_init);
EXPORT_SYMBOL(cdev_alloc);
EXPORT_SYMBOL(cdev_del);
EXPORT_SYMBOL(cdev_add);
EXPORT_SYMBOL(register_chrdev);
EXPORT_SYMBOL(unregister_chrdev);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/char_dev.c
	3	*
	4	* Copyright (C) 1991, 1992 Linus Torvalds
	5	*/
	6
1da177e4 LT	7	#include <linux/init.h>
	8	#include <linux/fs.h>
	9	#include <linux/slab.h>
	10	#include <linux/string.h>
	11
	12	#include <linux/major.h>
	13	#include <linux/errno.h>
	14	#include <linux/module.h>
	15	#include <linux/smp_lock.h>
68eef3b4	16	#include <linux/seq_file.h>
1da177e4 LT	17
	18	#include <linux/kobject.h>
	19	#include <linux/kobj_map.h>
	20	#include <linux/cdev.h>
58383af6	21	#include <linux/mutex.h>
1da177e4 LT	22
	23	#ifdef CONFIG_KMOD
	24	#include <linux/kmod.h>
	25	#endif
	26
	27	static struct kobj_map *cdev_map;
	28
58383af6	29	static DEFINE_MUTEX(chrdevs_lock);
1da177e4 LT	30
	31	static struct char_device_struct {
	32	struct char_device_struct *next;
	33	unsigned int major;
	34	unsigned int baseminor;
	35	int minorct;
7170be5f	36	char name[64];
1da177e4 LT	37	struct file_operations *fops;
1da177e4 LT	38	struct cdev cdev; / will die */
68eef3b4	39	} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
1da177e4 LT	40
	41	/* index in the above */
	42	static inline int major_to_index(int major)
	43	{
68eef3b4	44	return major % CHRDEV_MAJOR_HASH_SIZE;
7170be5f NH	45	}
7170be5f NH	46
68eef3b4	47	#ifdef CONFIG_PROC_FS
7170be5f	48
68eef3b4	49	void chrdev_show(struct seq_file *f, off_t offset)
7170be5f NH	50	{
7170be5f NH	51	struct char_device_struct *cd;
7170be5f	52
68eef3b4 JK	53	if (offset < CHRDEV_MAJOR_HASH_SIZE) {
	54	mutex_lock(&chrdevs_lock);
	55	for (cd = chrdevs[offset]; cd; cd = cd->next)
	56	seq_printf(f, "%3d %s\n", cd->major, cd->name);
	57	mutex_unlock(&chrdevs_lock);
1da177e4	58	}
7170be5f NH	59	}
7170be5f NH	60
68eef3b4	61	#endif /* CONFIG_PROC_FS */
1da177e4 LT	62
	63	/*
	64	* Register a single major with a specified minor range.
	65	*
	66	* If major == 0 this functions will dynamically allocate a major and return
	67	* its number.
	68	*
	69	* If major > 0 this function will attempt to reserve the passed range of
	70	* minors and will return zero on success.
	71	*
	72	* Returns a -ve errno on failure.
	73	*/
	74	static struct char_device_struct *
	75	__register_chrdev_region(unsigned int major, unsigned int baseminor,
	76	int minorct, const char *name)
	77	{
	78	struct char_device_struct cd, *cp;
	79	int ret = 0;
	80	int i;
	81
11b0b5ab	82	cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
1da177e4 LT	83	if (cd == NULL)
	84	return ERR_PTR(-ENOMEM);
	85
58383af6	86	mutex_lock(&chrdevs_lock);
1da177e4 LT	87
	88	/* temporary */
	89	if (major == 0) {
	90	for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
	91	if (chrdevs[i] == NULL)
	92	break;
	93	}
	94
	95	if (i == 0) {
	96	ret = -EBUSY;
	97	goto out;
	98	}
	99	major = i;
	100	ret = major;
	101	}
	102
	103	cd->major = major;
	104	cd->baseminor = baseminor;
	105	cd->minorct = minorct;
7170be5f	106	strncpy(cd->name,name, 64);
1da177e4 LT	107
	108	i = major_to_index(major);
	109
	110	for (cp = &chrdevs[i]; cp; cp = &(cp)->next)
	111	if ((*cp)->major > major \|\|
	112	((cp)->major == major && (cp)->baseminor >= baseminor))
	113	break;
	114	if (cp && (cp)->major == major &&
	115	(*cp)->baseminor < baseminor + minorct) {
	116	ret = -EBUSY;
	117	goto out;
	118	}
	119	cd->next = *cp;
	120	*cp = cd;
58383af6	121	mutex_unlock(&chrdevs_lock);
1da177e4 LT	122	return cd;
1da177e4 LT	123	out:
58383af6	124	mutex_unlock(&chrdevs_lock);
1da177e4 LT	125	kfree(cd);
	126	return ERR_PTR(ret);
	127	}
	128
	129	static struct char_device_struct *
	130	__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
	131	{
	132	struct char_device_struct cd = NULL, *cp;
	133	int i = major_to_index(major);
	134
58383af6	135	mutex_lock(&chrdevs_lock);
1da177e4 LT	136	for (cp = &chrdevs[i]; cp; cp = &(cp)->next)
	137	if ((*cp)->major == major &&
	138	(*cp)->baseminor == baseminor &&
	139	(*cp)->minorct == minorct)
	140	break;
	141	if (*cp) {
	142	cd = *cp;
	143	*cp = cd->next;
	144	}
58383af6	145	mutex_unlock(&chrdevs_lock);
1da177e4 LT	146	return cd;
	147	}
	148
	149	int register_chrdev_region(dev_t from, unsigned count, const char *name)
	150	{
	151	struct char_device_struct *cd;
	152	dev_t to = from + count;
	153	dev_t n, next;
	154
	155	for (n = from; n < to; n = next) {
	156	next = MKDEV(MAJOR(n)+1, 0);
	157	if (next > to)
	158	next = to;
	159	cd = __register_chrdev_region(MAJOR(n), MINOR(n),
	160	next - n, name);
	161	if (IS_ERR(cd))
	162	goto fail;
	163	}
	164	return 0;
	165	fail:
	166	to = n;
	167	for (n = from; n < to; n = next) {
	168	next = MKDEV(MAJOR(n)+1, 0);
	169	kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
	170	}
	171	return PTR_ERR(cd);
	172	}
	173
	174	int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
	175	const char *name)
	176	{
	177	struct char_device_struct *cd;
	178	cd = __register_chrdev_region(0, baseminor, count, name);
	179	if (IS_ERR(cd))
	180	return PTR_ERR(cd);
	181	*dev = MKDEV(cd->major, cd->baseminor);
	182	return 0;
	183	}
	184
d247e2c6 REB	185	/**
	186	* register_chrdev() - Register a major number for character devices.
	187	* @major: major device number or 0 for dynamic allocation
	188	* @name: name of this range of devices
	189	* @fops: file operations associated with this devices
	190	*
	191	* If @major == 0 this functions will dynamically allocate a major and return
	192	* its number.
	193	*
	194	* If @major > 0 this function will attempt to reserve a device with the given
	195	* major number and will return zero on success.
	196	*
	197	* Returns a -ve errno on failure.
	198	*
	199	* The name of this device has nothing to do with the name of the device in
	200	* /dev. It only helps to keep track of the different owners of devices. If
	201	* your module name has only one type of devices it's ok to use e.g. the name
	202	* of the module here.
	203	*
	204	* This function registers a range of 256 minor numbers. The first minor number
	205	* is 0.
	206	*/
1da177e4	207	int register_chrdev(unsigned int major, const char *name,
99ac48f5	208	const struct file_operations *fops)
1da177e4 LT	209	{
	210	struct char_device_struct *cd;
	211	struct cdev *cdev;
	212	char *s;
	213	int err = -ENOMEM;
	214
	215	cd = __register_chrdev_region(major, 0, 256, name);
	216	if (IS_ERR(cd))
	217	return PTR_ERR(cd);
	218
	219	cdev = cdev_alloc();
	220	if (!cdev)
	221	goto out2;
	222
	223	cdev->owner = fops->owner;
	224	cdev->ops = fops;
	225	kobject_set_name(&cdev->kobj, "%s", name);
	226	for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
	227	*s = '!';
	228
	229	err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
	230	if (err)
	231	goto out;
	232
	233	cd->cdev = cdev;
	234
	235	return major ? 0 : cd->major;
	236	out:
	237	kobject_put(&cdev->kobj);
	238	out2:
	239	kfree(__unregister_chrdev_region(cd->major, 0, 256));
	240	return err;
	241	}
	242
	243	void unregister_chrdev_region(dev_t from, unsigned count)
	244	{
	245	dev_t to = from + count;
	246	dev_t n, next;
	247
	248	for (n = from; n < to; n = next) {
	249	next = MKDEV(MAJOR(n)+1, 0);
	250	if (next > to)
	251	next = to;
	252	kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
	253	}
	254	}
	255
	256	int unregister_chrdev(unsigned int major, const char *name)
	257	{
	258	struct char_device_struct *cd;
	259	cd = __unregister_chrdev_region(major, 0, 256);
	260	if (cd && cd->cdev)
	261	cdev_del(cd->cdev);
	262	kfree(cd);
	263	return 0;
	264	}
	265
	266	static DEFINE_SPINLOCK(cdev_lock);
	267
	268	static struct kobject cdev_get(struct cdev p)
	269	{
	270	struct module *owner = p->owner;
	271	struct kobject *kobj;
	272
273	if (owner && !try_module_get(owner))
274	return NULL;
275	kobj = kobject_get(&p->kobj);
276	if (!kobj)
277	module_put(owner);
278	return kobj;
279	}
280
281	void cdev_put(struct cdev *p)
282	{
283	if (p) {
7da6844c	284	struct module *owner = p->owner;
1da177e4	285	kobject_put(&p->kobj);
7da6844c	286	module_put(owner);
1da177e4 LT	287	}
	288	}
	289
	290	/*
	291	* Called every time a character special file is opened
	292	*/
	293	int chrdev_open(struct inode * inode, struct file * filp)
	294	{
	295	struct cdev *p;
	296	struct cdev *new = NULL;
	297	int ret = 0;
	298
	299	spin_lock(&cdev_lock);
	300	p = inode->i_cdev;
	301	if (!p) {
	302	struct kobject *kobj;
	303	int idx;
	304	spin_unlock(&cdev_lock);
	305	kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
	306	if (!kobj)
	307	return -ENXIO;
	308	new = container_of(kobj, struct cdev, kobj);
	309	spin_lock(&cdev_lock);
	310	p = inode->i_cdev;
	311	if (!p) {
	312	inode->i_cdev = p = new;
	313	inode->i_cindex = idx;
	314	list_add(&inode->i_devices, &p->list);
	315	new = NULL;
	316	} else if (!cdev_get(p))
	317	ret = -ENXIO;
	318	} else if (!cdev_get(p))
	319	ret = -ENXIO;
	320	spin_unlock(&cdev_lock);
	321	cdev_put(new);
	322	if (ret)
	323	return ret;
	324	filp->f_op = fops_get(p->ops);
	325	if (!filp->f_op) {
	326	cdev_put(p);
	327	return -ENXIO;
	328	}
	329	if (filp->f_op->open) {
	330	lock_kernel();
	331	ret = filp->f_op->open(inode,filp);
	332	unlock_kernel();
	333	}
	334	if (ret)
	335	cdev_put(p);
	336	return ret;
	337	}
	338
	339	void cd_forget(struct inode *inode)
	340	{
	341	spin_lock(&cdev_lock);
	342	list_del_init(&inode->i_devices);
	343	inode->i_cdev = NULL;
	344	spin_unlock(&cdev_lock);
	345	}
	346
75c96f85	347	static void cdev_purge(struct cdev *cdev)
1da177e4 LT	348	{
	349	spin_lock(&cdev_lock);
	350	while (!list_empty(&cdev->list)) {
	351	struct inode *inode;
	352	inode = container_of(cdev->list.next, struct inode, i_devices);
	353	list_del_init(&inode->i_devices);
	354	inode->i_cdev = NULL;
	355	}
	356	spin_unlock(&cdev_lock);
	357	}
	358
	359	/*
	360	* Dummy default file-operations: the only thing this does
	361	* is contain the open that then fills in the correct operations
	362	* depending on the special file...
	363	*/
4b6f5d20	364	const struct file_operations def_chr_fops = {
1da177e4 LT	365	.open = chrdev_open,
	366	};
	367
	368	static struct kobject exact_match(dev_t dev, int part, void *data)
	369	{
	370	struct cdev *p = data;
	371	return &p->kobj;
	372	}
	373
	374	static int exact_lock(dev_t dev, void *data)
	375	{
	376	struct cdev *p = data;
	377	return cdev_get(p) ? 0 : -1;
	378	}
	379
	380	int cdev_add(struct cdev *p, dev_t dev, unsigned count)
	381	{
	382	p->dev = dev;
	383	p->count = count;
	384	return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
	385	}
	386
	387	static void cdev_unmap(dev_t dev, unsigned count)
	388	{
	389	kobj_unmap(cdev_map, dev, count);
	390	}
	391
	392	void cdev_del(struct cdev *p)
	393	{
	394	cdev_unmap(p->dev, p->count);
	395	kobject_put(&p->kobj);
	396	}
	397
	398
	399	static void cdev_default_release(struct kobject *kobj)
	400	{
	401	struct cdev *p = container_of(kobj, struct cdev, kobj);
	402	cdev_purge(p);
	403	}
	404
	405	static void cdev_dynamic_release(struct kobject *kobj)
	406	{
	407	struct cdev *p = container_of(kobj, struct cdev, kobj);
	408	cdev_purge(p);
	409	kfree(p);
	410	}
	411
	412	static struct kobj_type ktype_cdev_default = {
	413	.release = cdev_default_release,
	414	};
	415
	416	static struct kobj_type ktype_cdev_dynamic = {
	417	.release = cdev_dynamic_release,
	418	};
	419
	420	struct cdev *cdev_alloc(void)
	421	{
11b0b5ab	422	struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
1da177e4	423	if (p) {
1da177e4 LT	424	p->kobj.ktype = &ktype_cdev_dynamic;
	425	INIT_LIST_HEAD(&p->list);
	426	kobject_init(&p->kobj);
	427	}
	428	return p;
	429	}
	430
99ac48f5	431	void cdev_init(struct cdev cdev, const struct file_operations fops)
1da177e4 LT	432	{
	433	memset(cdev, 0, sizeof *cdev);
	434	INIT_LIST_HEAD(&cdev->list);
	435	cdev->kobj.ktype = &ktype_cdev_default;
	436	kobject_init(&cdev->kobj);
	437	cdev->ops = fops;
	438	}
	439
	440	static struct kobject base_probe(dev_t dev, int part, void *data)
	441	{
	442	if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
	443	/* Make old-style 2.4 aliases work */
	444	request_module("char-major-%d", MAJOR(dev));
	445	return NULL;
	446	}
	447
	448	void __init chrdev_init(void)
	449	{
	450	cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
	451	}
	452
	453
	454	/* Let modules do char dev stuff */
	455	EXPORT_SYMBOL(register_chrdev_region);
	456	EXPORT_SYMBOL(unregister_chrdev_region);
	457	EXPORT_SYMBOL(alloc_chrdev_region);
	458	EXPORT_SYMBOL(cdev_init);
	459	EXPORT_SYMBOL(cdev_alloc);
	460	EXPORT_SYMBOL(cdev_del);
	461	EXPORT_SYMBOL(cdev_add);
	462	EXPORT_SYMBOL(register_chrdev);
	463	EXPORT_SYMBOL(unregister_chrdev);