[mirror_ubuntu-bionic-kernel.git] / fs / char_dev.c

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

#include <linux/config.h>
#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/devfs_fs_kernel.h>

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

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

static struct kobj_map *cdev_map;

#define MAX_PROBE_HASH 255	/* random */

static DECLARE_MUTEX(chrdevs_lock);

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

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

/* get char device names in somewhat random order */
int get_chrdev_list(char *page)
{
	struct char_device_struct *cd;
	int i, len;

	len = sprintf(page, "Character devices:\n");

	down(&chrdevs_lock);
	for (i = 0; i < ARRAY_SIZE(chrdevs) ; i++) {
		for (cd = chrdevs[i]; cd; cd = cd->next) {
			/*
			 * if the current name, plus the 5 extra characters
			 * in the device line for this entry
			 * would run us off the page, we're done
			 */
			if ((len+strlen(cd->name) + 5) >= PAGE_SIZE)
				goto page_full;


			len += sprintf(page+len, "%3d %s\n",
				       cd->major, cd->name);
		}
	}
page_full:
	up(&chrdevs_lock);

	return len;
}

/*
 * 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 = kmalloc(sizeof(struct char_device_struct), GFP_KERNEL);
	if (cd == NULL)
		return ERR_PTR(-ENOMEM);

	memset(cd, 0, sizeof(struct char_device_struct));

	down(&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;
	cd->name = name;

	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;
	up(&chrdevs_lock);
	return cd;
out:
	up(&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);

	up(&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;
	}
	up(&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;
}

int register_chrdev(unsigned int major, const char *name,
		    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) {
		kobject_put(&p->kobj);
		module_put(p->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...
 */
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 = kmalloc(sizeof(struct cdev), GFP_KERNEL);
	if (p) {
		memset(p, 0, sizeof(struct cdev));
		p->kobj.ktype = &ktype_cdev_dynamic;
		INIT_LIST_HEAD(&p->list);
		kobject_init(&p->kobj);
	}
	return p;
}

void cdev_init(struct cdev *cdev, 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
	7	#include <linux/config.h>
	8	#include <linux/init.h>
	9	#include <linux/fs.h>
	10	#include <linux/slab.h>
	11	#include <linux/string.h>
	12
	13	#include <linux/major.h>
	14	#include <linux/errno.h>
	15	#include <linux/module.h>
	16	#include <linux/smp_lock.h>
	17	#include <linux/devfs_fs_kernel.h>
	18
	19	#include <linux/kobject.h>
	20	#include <linux/kobj_map.h>
	21	#include <linux/cdev.h>
	22
	23	#ifdef CONFIG_KMOD
	24	#include <linux/kmod.h>
	25	#endif
	26
	27	static struct kobj_map *cdev_map;
	28
1d4d5b32	29	#define MAX_PROBE_HASH 255 /* random */
1da177e4 LT	30
	31	static DECLARE_MUTEX(chrdevs_lock);
	32
	33	static struct char_device_struct {
	34	struct char_device_struct *next;
	35	unsigned int major;
	36	unsigned int baseminor;
	37	int minorct;
	38	const char *name;
	39	struct file_operations *fops;
	40	struct cdev cdev; / will die */
	41	} *chrdevs[MAX_PROBE_HASH];
	42
	43	/* index in the above */
	44	static inline int major_to_index(int major)
	45	{
	46	return major % MAX_PROBE_HASH;
	47	}
	48
	49	/* get char device names in somewhat random order */
	50	int get_chrdev_list(char *page)
	51	{
	52	struct char_device_struct *cd;
	53	int i, len;
	54
	55	len = sprintf(page, "Character devices:\n");
	56
	57	down(&chrdevs_lock);
	58	for (i = 0; i < ARRAY_SIZE(chrdevs) ; i++) {
ac20427e NH	59	for (cd = chrdevs[i]; cd; cd = cd->next) {
	60	/*
	61	* if the current name, plus the 5 extra characters
	62	* in the device line for this entry
	63	* would run us off the page, we're done
	64	*/
	65	if ((len+strlen(cd->name) + 5) >= PAGE_SIZE)
	66	goto page_full;
	67
	68
1da177e4 LT	69	len += sprintf(page+len, "%3d %s\n",
1da177e4 LT	70	cd->major, cd->name);
ac20427e	71	}
1da177e4	72	}
ac20427e	73	page_full:
1da177e4 LT	74	up(&chrdevs_lock);
	75
	76	return len;
	77	}
	78
	79	/*
	80	* Register a single major with a specified minor range.
	81	*
	82	* If major == 0 this functions will dynamically allocate a major and return
	83	* its number.
	84	*
	85	* If major > 0 this function will attempt to reserve the passed range of
	86	* minors and will return zero on success.
	87	*
	88	* Returns a -ve errno on failure.
	89	*/
	90	static struct char_device_struct *
	91	__register_chrdev_region(unsigned int major, unsigned int baseminor,
	92	int minorct, const char *name)
	93	{
	94	struct char_device_struct cd, *cp;
	95	int ret = 0;
	96	int i;
	97
	98	cd = kmalloc(sizeof(struct char_device_struct), GFP_KERNEL);
	99	if (cd == NULL)
	100	return ERR_PTR(-ENOMEM);
	101
	102	memset(cd, 0, sizeof(struct char_device_struct));
	103
	104	down(&chrdevs_lock);
	105
	106	/* temporary */
	107	if (major == 0) {
	108	for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
	109	if (chrdevs[i] == NULL)
	110	break;
	111	}
	112
	113	if (i == 0) {
	114	ret = -EBUSY;
	115	goto out;
	116	}
	117	major = i;
	118	ret = major;
	119	}
	120
	121	cd->major = major;
	122	cd->baseminor = baseminor;
	123	cd->minorct = minorct;
	124	cd->name = name;
	125
	126	i = major_to_index(major);
	127
	128	for (cp = &chrdevs[i]; cp; cp = &(cp)->next)
	129	if ((*cp)->major > major \|\|
	130	((cp)->major == major && (cp)->baseminor >= baseminor))
	131	break;
	132	if (cp && (cp)->major == major &&
	133	(*cp)->baseminor < baseminor + minorct) {
	134	ret = -EBUSY;
	135	goto out;
	136	}
	137	cd->next = *cp;
138	*cp = cd;
139	up(&chrdevs_lock);
140	return cd;
141	out:
142	up(&chrdevs_lock);
143	kfree(cd);
144	return ERR_PTR(ret);
145	}
146
147	static struct char_device_struct *
148	__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
149	{
150	struct char_device_struct cd = NULL, *cp;
151	int i = major_to_index(major);
152
153	up(&chrdevs_lock);
154	for (cp = &chrdevs[i]; cp; cp = &(cp)->next)
155	if ((*cp)->major == major &&
156	(*cp)->baseminor == baseminor &&
157	(*cp)->minorct == minorct)
158	break;
159	if (*cp) {
160	cd = *cp;
161	*cp = cd->next;
162	}
163	up(&chrdevs_lock);
164	return cd;
165	}
166
167	int register_chrdev_region(dev_t from, unsigned count, const char *name)
168	{
169	struct char_device_struct *cd;
170	dev_t to = from + count;
171	dev_t n, next;
172
173	for (n = from; n < to; n = next) {
174	next = MKDEV(MAJOR(n)+1, 0);
175	if (next > to)
176	next = to;
177	cd = __register_chrdev_region(MAJOR(n), MINOR(n),
178	next - n, name);
179	if (IS_ERR(cd))
180	goto fail;
181	}
182	return 0;
183	fail:
184	to = n;
185	for (n = from; n < to; n = next) {
186	next = MKDEV(MAJOR(n)+1, 0);
187	kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
188	}
189	return PTR_ERR(cd);
190	}
191
192	int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
193	const char *name)
194	{
195	struct char_device_struct *cd;
196	cd = __register_chrdev_region(0, baseminor, count, name);
197	if (IS_ERR(cd))
198	return PTR_ERR(cd);
199	*dev = MKDEV(cd->major, cd->baseminor);
200	return 0;
201	}
202
203	int register_chrdev(unsigned int major, const char *name,
204	struct file_operations *fops)
205	{
206	struct char_device_struct *cd;
207	struct cdev *cdev;
208	char *s;
209	int err = -ENOMEM;
210
211	cd = __register_chrdev_region(major, 0, 256, name);
212	if (IS_ERR(cd))
213	return PTR_ERR(cd);
214
215	cdev = cdev_alloc();
216	if (!cdev)
217	goto out2;
218
219	cdev->owner = fops->owner;
220	cdev->ops = fops;
221	kobject_set_name(&cdev->kobj, "%s", name);
222	for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
223	*s = '!';
224
225	err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
226	if (err)
227	goto out;
228
229	cd->cdev = cdev;
230
231	return major ? 0 : cd->major;
232	out:
233	kobject_put(&cdev->kobj);
234	out2:
235	kfree(__unregister_chrdev_region(cd->major, 0, 256));
236	return err;
237	}
238
239	void unregister_chrdev_region(dev_t from, unsigned count)
240	{
241	dev_t to = from + count;
242	dev_t n, next;
243
244	for (n = from; n < to; n = next) {
245	next = MKDEV(MAJOR(n)+1, 0);
246	if (next > to)
247	next = to;
248	kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
249	}
250	}
251
252	int unregister_chrdev(unsigned int major, const char *name)
253	{
254	struct char_device_struct *cd;
255	cd = __unregister_chrdev_region(major, 0, 256);
256	if (cd && cd->cdev)
257	cdev_del(cd->cdev);
258	kfree(cd);
259	return 0;
260	}
261
262	static DEFINE_SPINLOCK(cdev_lock);
263
264	static struct kobject cdev_get(struct cdev p)
265	{
266	struct module *owner = p->owner;
267	struct kobject *kobj;
268
269	if (owner && !try_module_get(owner))
270	return NULL;
271	kobj = kobject_get(&p->kobj);
272	if (!kobj)
273	module_put(owner);
274	return kobj;
275	}
276
277	void cdev_put(struct cdev *p)
278	{
279	if (p) {
280	kobject_put(&p->kobj);
281	module_put(p->owner);
282	}
283	}
284
285	/*
286	* Called every time a character special file is opened
287	*/
288	int chrdev_open(struct inode * inode, struct file * filp)
289	{
290	struct cdev *p;
291	struct cdev *new = NULL;
292	int ret = 0;
293
294	spin_lock(&cdev_lock);
295	p = inode->i_cdev;
296	if (!p) {
297	struct kobject *kobj;
298	int idx;
299	spin_unlock(&cdev_lock);
300	kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
301	if (!kobj)
302	return -ENXIO;
303	new = container_of(kobj, struct cdev, kobj);
304	spin_lock(&cdev_lock);
305	p = inode->i_cdev;
306	if (!p) {
307	inode->i_cdev = p = new;
308	inode->i_cindex = idx;
309	list_add(&inode->i_devices, &p->list);
310	new = NULL;
311	} else if (!cdev_get(p))
312	ret = -ENXIO;
313	} else if (!cdev_get(p))
314	ret = -ENXIO;
315	spin_unlock(&cdev_lock);
316	cdev_put(new);
317	if (ret)
318	return ret;
319	filp->f_op = fops_get(p->ops);
320	if (!filp->f_op) {
321	cdev_put(p);
322	return -ENXIO;
323	}
324	if (filp->f_op->open) {
325	lock_kernel();
326	ret = filp->f_op->open(inode,filp);
327	unlock_kernel();
328	}
329	if (ret)
330	cdev_put(p);
331	return ret;
332	}
333
334	void cd_forget(struct inode *inode)
335	{
336	spin_lock(&cdev_lock);
337	list_del_init(&inode->i_devices);
338	inode->i_cdev = NULL;
339	spin_unlock(&cdev_lock);
340	}
341
75c96f85	342	static void cdev_purge(struct cdev *cdev)
1da177e4 LT	343	{
	344	spin_lock(&cdev_lock);
	345	while (!list_empty(&cdev->list)) {
	346	struct inode *inode;
	347	inode = container_of(cdev->list.next, struct inode, i_devices);
	348	list_del_init(&inode->i_devices);
	349	inode->i_cdev = NULL;
	350	}
	351	spin_unlock(&cdev_lock);
	352	}
	353
	354	/*
	355	* Dummy default file-operations: the only thing this does
	356	* is contain the open that then fills in the correct operations
	357	* depending on the special file...
	358	*/
	359	struct file_operations def_chr_fops = {
	360	.open = chrdev_open,
	361	};
	362
	363	static struct kobject exact_match(dev_t dev, int part, void *data)
	364	{
	365	struct cdev *p = data;
	366	return &p->kobj;
	367	}
	368
	369	static int exact_lock(dev_t dev, void *data)
	370	{
	371	struct cdev *p = data;
	372	return cdev_get(p) ? 0 : -1;
	373	}
	374
	375	int cdev_add(struct cdev *p, dev_t dev, unsigned count)
	376	{
	377	p->dev = dev;
	378	p->count = count;
	379	return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
	380	}
	381
	382	static void cdev_unmap(dev_t dev, unsigned count)
	383	{
	384	kobj_unmap(cdev_map, dev, count);
	385	}
	386
	387	void cdev_del(struct cdev *p)
	388	{
	389	cdev_unmap(p->dev, p->count);
	390	kobject_put(&p->kobj);
	391	}
	392
	393
	394	static void cdev_default_release(struct kobject *kobj)
	395	{
	396	struct cdev *p = container_of(kobj, struct cdev, kobj);
	397	cdev_purge(p);
	398	}
	399
	400	static void cdev_dynamic_release(struct kobject *kobj)
	401	{
	402	struct cdev *p = container_of(kobj, struct cdev, kobj);
	403	cdev_purge(p);
	404	kfree(p);
	405	}
	406
407	static struct kobj_type ktype_cdev_default = {
408	.release = cdev_default_release,
409	};
410
411	static struct kobj_type ktype_cdev_dynamic = {
412	.release = cdev_dynamic_release,
413	};
414
415	struct cdev *cdev_alloc(void)
416	{
417	struct cdev *p = kmalloc(sizeof(struct cdev), GFP_KERNEL);
418	if (p) {
419	memset(p, 0, sizeof(struct cdev));
420	p->kobj.ktype = &ktype_cdev_dynamic;
421	INIT_LIST_HEAD(&p->list);
422	kobject_init(&p->kobj);
423	}
424	return p;
425	}
426
427	void cdev_init(struct cdev cdev, struct file_operations fops)
428	{
429	memset(cdev, 0, sizeof *cdev);
430	INIT_LIST_HEAD(&cdev->list);
431	cdev->kobj.ktype = &ktype_cdev_default;
432	kobject_init(&cdev->kobj);
433	cdev->ops = fops;
434	}
435
436	static struct kobject base_probe(dev_t dev, int part, void *data)
437	{
438	if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
439	/* Make old-style 2.4 aliases work */
440	request_module("char-major-%d", MAJOR(dev));
441	return NULL;
442	}
443
444	void __init chrdev_init(void)
445	{
446	cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
447	}
448
449
450	/* Let modules do char dev stuff */
451	EXPORT_SYMBOL(register_chrdev_region);
452	EXPORT_SYMBOL(unregister_chrdev_region);
453	EXPORT_SYMBOL(alloc_chrdev_region);
454	EXPORT_SYMBOL(cdev_init);
455	EXPORT_SYMBOL(cdev_alloc);
456	EXPORT_SYMBOL(cdev_del);
457	EXPORT_SYMBOL(cdev_add);
458	EXPORT_SYMBOL(register_chrdev);
459	EXPORT_SYMBOL(unregister_chrdev);