wusb: disable verification of the key generation algorithms
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / char_dev.c
blob700697a726187863a3d4557b27410192ad7d45d9
1 /*
2 * linux/fs/char_dev.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
7 #include <linux/init.h>
8 #include <linux/fs.h>
9 #include <linux/kdev_t.h>
10 #include <linux/slab.h>
11 #include <linux/string.h>
13 #include <linux/major.h>
14 #include <linux/errno.h>
15 #include <linux/module.h>
16 #include <linux/smp_lock.h>
17 #include <linux/seq_file.h>
19 #include <linux/kobject.h>
20 #include <linux/kobj_map.h>
21 #include <linux/cdev.h>
22 #include <linux/mutex.h>
23 #include <linux/backing-dev.h>
25 #include "internal.h"
28 * capabilities for /dev/mem, /dev/kmem and similar directly mappable character
29 * devices
30 * - permits shared-mmap for read, write and/or exec
31 * - does not permit private mmap in NOMMU mode (can't do COW)
32 * - no readahead or I/O queue unplugging required
34 struct backing_dev_info directly_mappable_cdev_bdi = {
35 .capabilities = (
36 #ifdef CONFIG_MMU
37 /* permit private copies of the data to be taken */
38 BDI_CAP_MAP_COPY |
39 #endif
40 /* permit direct mmap, for read, write or exec */
41 BDI_CAP_MAP_DIRECT |
42 BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP),
45 static struct kobj_map *cdev_map;
47 static DEFINE_MUTEX(chrdevs_lock);
49 static struct char_device_struct {
50 struct char_device_struct *next;
51 unsigned int major;
52 unsigned int baseminor;
53 int minorct;
54 char name[64];
55 struct cdev *cdev; /* will die */
56 } *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
58 /* index in the above */
59 static inline int major_to_index(int major)
61 return major % CHRDEV_MAJOR_HASH_SIZE;
64 #ifdef CONFIG_PROC_FS
66 void chrdev_show(struct seq_file *f, off_t offset)
68 struct char_device_struct *cd;
70 if (offset < CHRDEV_MAJOR_HASH_SIZE) {
71 mutex_lock(&chrdevs_lock);
72 for (cd = chrdevs[offset]; cd; cd = cd->next)
73 seq_printf(f, "%3d %s\n", cd->major, cd->name);
74 mutex_unlock(&chrdevs_lock);
78 #endif /* CONFIG_PROC_FS */
81 * Register a single major with a specified minor range.
83 * If major == 0 this functions will dynamically allocate a major and return
84 * its number.
86 * If major > 0 this function will attempt to reserve the passed range of
87 * minors and will return zero on success.
89 * Returns a -ve errno on failure.
91 static struct char_device_struct *
92 __register_chrdev_region(unsigned int major, unsigned int baseminor,
93 int minorct, const char *name)
95 struct char_device_struct *cd, **cp;
96 int ret = 0;
97 int i;
99 cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
100 if (cd == NULL)
101 return ERR_PTR(-ENOMEM);
103 mutex_lock(&chrdevs_lock);
105 /* temporary */
106 if (major == 0) {
107 for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
108 if (chrdevs[i] == NULL)
109 break;
112 if (i == 0) {
113 ret = -EBUSY;
114 goto out;
116 major = i;
117 ret = major;
120 cd->major = major;
121 cd->baseminor = baseminor;
122 cd->minorct = minorct;
123 strncpy(cd->name,name, 64);
125 i = major_to_index(major);
127 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
128 if ((*cp)->major > major ||
129 ((*cp)->major == major &&
130 (((*cp)->baseminor >= baseminor) ||
131 ((*cp)->baseminor + (*cp)->minorct > baseminor))))
132 break;
134 /* Check for overlapping minor ranges. */
135 if (*cp && (*cp)->major == major) {
136 int old_min = (*cp)->baseminor;
137 int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
138 int new_min = baseminor;
139 int new_max = baseminor + minorct - 1;
141 /* New driver overlaps from the left. */
142 if (new_max >= old_min && new_max <= old_max) {
143 ret = -EBUSY;
144 goto out;
147 /* New driver overlaps from the right. */
148 if (new_min <= old_max && new_min >= old_min) {
149 ret = -EBUSY;
150 goto out;
154 cd->next = *cp;
155 *cp = cd;
156 mutex_unlock(&chrdevs_lock);
157 return cd;
158 out:
159 mutex_unlock(&chrdevs_lock);
160 kfree(cd);
161 return ERR_PTR(ret);
164 static struct char_device_struct *
165 __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
167 struct char_device_struct *cd = NULL, **cp;
168 int i = major_to_index(major);
170 mutex_lock(&chrdevs_lock);
171 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
172 if ((*cp)->major == major &&
173 (*cp)->baseminor == baseminor &&
174 (*cp)->minorct == minorct)
175 break;
176 if (*cp) {
177 cd = *cp;
178 *cp = cd->next;
180 mutex_unlock(&chrdevs_lock);
181 return cd;
185 * register_chrdev_region() - register a range of device numbers
186 * @from: the first in the desired range of device numbers; must include
187 * the major number.
188 * @count: the number of consecutive device numbers required
189 * @name: the name of the device or driver.
191 * Return value is zero on success, a negative error code on failure.
193 int register_chrdev_region(dev_t from, unsigned count, const char *name)
195 struct char_device_struct *cd;
196 dev_t to = from + count;
197 dev_t n, next;
199 for (n = from; n < to; n = next) {
200 next = MKDEV(MAJOR(n)+1, 0);
201 if (next > to)
202 next = to;
203 cd = __register_chrdev_region(MAJOR(n), MINOR(n),
204 next - n, name);
205 if (IS_ERR(cd))
206 goto fail;
208 return 0;
209 fail:
210 to = n;
211 for (n = from; n < to; n = next) {
212 next = MKDEV(MAJOR(n)+1, 0);
213 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
215 return PTR_ERR(cd);
219 * alloc_chrdev_region() - register a range of char device numbers
220 * @dev: output parameter for first assigned number
221 * @baseminor: first of the requested range of minor numbers
222 * @count: the number of minor numbers required
223 * @name: the name of the associated device or driver
225 * Allocates a range of char device numbers. The major number will be
226 * chosen dynamically, and returned (along with the first minor number)
227 * in @dev. Returns zero or a negative error code.
229 int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
230 const char *name)
232 struct char_device_struct *cd;
233 cd = __register_chrdev_region(0, baseminor, count, name);
234 if (IS_ERR(cd))
235 return PTR_ERR(cd);
236 *dev = MKDEV(cd->major, cd->baseminor);
237 return 0;
241 * register_chrdev() - Register a major number for character devices.
242 * @major: major device number or 0 for dynamic allocation
243 * @name: name of this range of devices
244 * @fops: file operations associated with this devices
246 * If @major == 0 this functions will dynamically allocate a major and return
247 * its number.
249 * If @major > 0 this function will attempt to reserve a device with the given
250 * major number and will return zero on success.
252 * Returns a -ve errno on failure.
254 * The name of this device has nothing to do with the name of the device in
255 * /dev. It only helps to keep track of the different owners of devices. If
256 * your module name has only one type of devices it's ok to use e.g. the name
257 * of the module here.
259 * This function registers a range of 256 minor numbers. The first minor number
260 * is 0.
262 int register_chrdev(unsigned int major, const char *name,
263 const struct file_operations *fops)
265 struct char_device_struct *cd;
266 struct cdev *cdev;
267 char *s;
268 int err = -ENOMEM;
270 cd = __register_chrdev_region(major, 0, 256, name);
271 if (IS_ERR(cd))
272 return PTR_ERR(cd);
274 cdev = cdev_alloc();
275 if (!cdev)
276 goto out2;
278 cdev->owner = fops->owner;
279 cdev->ops = fops;
280 kobject_set_name(&cdev->kobj, "%s", name);
281 for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
282 *s = '!';
284 err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
285 if (err)
286 goto out;
288 cd->cdev = cdev;
290 return major ? 0 : cd->major;
291 out:
292 kobject_put(&cdev->kobj);
293 out2:
294 kfree(__unregister_chrdev_region(cd->major, 0, 256));
295 return err;
299 * unregister_chrdev_region() - return a range of device numbers
300 * @from: the first in the range of numbers to unregister
301 * @count: the number of device numbers to unregister
303 * This function will unregister a range of @count device numbers,
304 * starting with @from. The caller should normally be the one who
305 * allocated those numbers in the first place...
307 void unregister_chrdev_region(dev_t from, unsigned count)
309 dev_t to = from + count;
310 dev_t n, next;
312 for (n = from; n < to; n = next) {
313 next = MKDEV(MAJOR(n)+1, 0);
314 if (next > to)
315 next = to;
316 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
320 void unregister_chrdev(unsigned int major, const char *name)
322 struct char_device_struct *cd;
323 cd = __unregister_chrdev_region(major, 0, 256);
324 if (cd && cd->cdev)
325 cdev_del(cd->cdev);
326 kfree(cd);
329 static DEFINE_SPINLOCK(cdev_lock);
331 static struct kobject *cdev_get(struct cdev *p)
333 struct module *owner = p->owner;
334 struct kobject *kobj;
336 if (owner && !try_module_get(owner))
337 return NULL;
338 kobj = kobject_get(&p->kobj);
339 if (!kobj)
340 module_put(owner);
341 return kobj;
344 void cdev_put(struct cdev *p)
346 if (p) {
347 struct module *owner = p->owner;
348 kobject_put(&p->kobj);
349 module_put(owner);
354 * Called every time a character special file is opened
356 static int chrdev_open(struct inode *inode, struct file *filp)
358 struct cdev *p;
359 struct cdev *new = NULL;
360 int ret = 0;
362 spin_lock(&cdev_lock);
363 p = inode->i_cdev;
364 if (!p) {
365 struct kobject *kobj;
366 int idx;
367 spin_unlock(&cdev_lock);
368 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
369 if (!kobj)
370 return -ENXIO;
371 new = container_of(kobj, struct cdev, kobj);
372 spin_lock(&cdev_lock);
373 /* Check i_cdev again in case somebody beat us to it while
374 we dropped the lock. */
375 p = inode->i_cdev;
376 if (!p) {
377 inode->i_cdev = p = new;
378 inode->i_cindex = idx;
379 list_add(&inode->i_devices, &p->list);
380 new = NULL;
381 } else if (!cdev_get(p))
382 ret = -ENXIO;
383 } else if (!cdev_get(p))
384 ret = -ENXIO;
385 spin_unlock(&cdev_lock);
386 cdev_put(new);
387 if (ret)
388 return ret;
390 ret = -ENXIO;
391 filp->f_op = fops_get(p->ops);
392 if (!filp->f_op)
393 goto out_cdev_put;
395 if (filp->f_op->open) {
396 ret = filp->f_op->open(inode,filp);
397 if (ret)
398 goto out_cdev_put;
401 return 0;
403 out_cdev_put:
404 cdev_put(p);
405 return ret;
408 void cd_forget(struct inode *inode)
410 spin_lock(&cdev_lock);
411 list_del_init(&inode->i_devices);
412 inode->i_cdev = NULL;
413 spin_unlock(&cdev_lock);
416 static void cdev_purge(struct cdev *cdev)
418 spin_lock(&cdev_lock);
419 while (!list_empty(&cdev->list)) {
420 struct inode *inode;
421 inode = container_of(cdev->list.next, struct inode, i_devices);
422 list_del_init(&inode->i_devices);
423 inode->i_cdev = NULL;
425 spin_unlock(&cdev_lock);
429 * Dummy default file-operations: the only thing this does
430 * is contain the open that then fills in the correct operations
431 * depending on the special file...
433 const struct file_operations def_chr_fops = {
434 .open = chrdev_open,
437 static struct kobject *exact_match(dev_t dev, int *part, void *data)
439 struct cdev *p = data;
440 return &p->kobj;
443 static int exact_lock(dev_t dev, void *data)
445 struct cdev *p = data;
446 return cdev_get(p) ? 0 : -1;
450 * cdev_add() - add a char device to the system
451 * @p: the cdev structure for the device
452 * @dev: the first device number for which this device is responsible
453 * @count: the number of consecutive minor numbers corresponding to this
454 * device
456 * cdev_add() adds the device represented by @p to the system, making it
457 * live immediately. A negative error code is returned on failure.
459 int cdev_add(struct cdev *p, dev_t dev, unsigned count)
461 p->dev = dev;
462 p->count = count;
463 return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
466 static void cdev_unmap(dev_t dev, unsigned count)
468 kobj_unmap(cdev_map, dev, count);
472 * cdev_del() - remove a cdev from the system
473 * @p: the cdev structure to be removed
475 * cdev_del() removes @p from the system, possibly freeing the structure
476 * itself.
478 void cdev_del(struct cdev *p)
480 cdev_unmap(p->dev, p->count);
481 kobject_put(&p->kobj);
485 static void cdev_default_release(struct kobject *kobj)
487 struct cdev *p = container_of(kobj, struct cdev, kobj);
488 cdev_purge(p);
491 static void cdev_dynamic_release(struct kobject *kobj)
493 struct cdev *p = container_of(kobj, struct cdev, kobj);
494 cdev_purge(p);
495 kfree(p);
498 static struct kobj_type ktype_cdev_default = {
499 .release = cdev_default_release,
502 static struct kobj_type ktype_cdev_dynamic = {
503 .release = cdev_dynamic_release,
507 * cdev_alloc() - allocate a cdev structure
509 * Allocates and returns a cdev structure, or NULL on failure.
511 struct cdev *cdev_alloc(void)
513 struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
514 if (p) {
515 INIT_LIST_HEAD(&p->list);
516 kobject_init(&p->kobj, &ktype_cdev_dynamic);
518 return p;
522 * cdev_init() - initialize a cdev structure
523 * @cdev: the structure to initialize
524 * @fops: the file_operations for this device
526 * Initializes @cdev, remembering @fops, making it ready to add to the
527 * system with cdev_add().
529 void cdev_init(struct cdev *cdev, const struct file_operations *fops)
531 memset(cdev, 0, sizeof *cdev);
532 INIT_LIST_HEAD(&cdev->list);
533 kobject_init(&cdev->kobj, &ktype_cdev_default);
534 cdev->ops = fops;
537 static struct kobject *base_probe(dev_t dev, int *part, void *data)
539 if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
540 /* Make old-style 2.4 aliases work */
541 request_module("char-major-%d", MAJOR(dev));
542 return NULL;
545 void __init chrdev_init(void)
547 cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
548 bdi_init(&directly_mappable_cdev_bdi);
552 /* Let modules do char dev stuff */
553 EXPORT_SYMBOL(register_chrdev_region);
554 EXPORT_SYMBOL(unregister_chrdev_region);
555 EXPORT_SYMBOL(alloc_chrdev_region);
556 EXPORT_SYMBOL(cdev_init);
557 EXPORT_SYMBOL(cdev_alloc);
558 EXPORT_SYMBOL(cdev_del);
559 EXPORT_SYMBOL(cdev_add);
560 EXPORT_SYMBOL(register_chrdev);
561 EXPORT_SYMBOL(unregister_chrdev);
562 EXPORT_SYMBOL(directly_mappable_cdev_bdi);