[PATCH] use kzalloc and kcalloc in core fs code
[linux-2.6.git] / fs / char_dev.c
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 #include <linux/mutex.h>
23
24 #ifdef CONFIG_KMOD
25 #include <linux/kmod.h>
26 #endif
27
28 static struct kobj_map *cdev_map;
29
30 #define MAX_PROBE_HASH 255      /* random */
31
32 static DEFINE_MUTEX(chrdevs_lock);
33
34 static struct char_device_struct {
35         struct char_device_struct *next;
36         unsigned int major;
37         unsigned int baseminor;
38         int minorct;
39         char name[64];
40         struct file_operations *fops;
41         struct cdev *cdev;              /* will die */
42 } *chrdevs[MAX_PROBE_HASH];
43
44 /* index in the above */
45 static inline int major_to_index(int major)
46 {
47         return major % MAX_PROBE_HASH;
48 }
49
50 struct chrdev_info {
51         int index;
52         struct char_device_struct *cd;
53 };
54
55 void *get_next_chrdev(void *dev)
56 {
57         struct chrdev_info *info;
58
59         if (dev == NULL) {
60                 info = kmalloc(sizeof(*info), GFP_KERNEL);
61                 if (!info)
62                         goto out;
63                 info->index=0;
64                 info->cd = chrdevs[info->index];
65                 if (info->cd)
66                         goto out;
67         } else {
68                 info = dev;
69         }
70
71         while (info->index < ARRAY_SIZE(chrdevs)) {
72                 if (info->cd)
73                         info->cd = info->cd->next;
74                 if (info->cd)
75                         goto out;
76                 /*
77                  * No devices on this chain, move to the next
78                  */
79                 info->index++;
80                 info->cd = (info->index < ARRAY_SIZE(chrdevs)) ?
81                         chrdevs[info->index] : NULL;
82                 if (info->cd)
83                         goto out;
84         }
85
86 out:
87         return info;
88 }
89
90 void *acquire_chrdev_list(void)
91 {
92         mutex_lock(&chrdevs_lock);
93         return get_next_chrdev(NULL);
94 }
95
96 void release_chrdev_list(void *dev)
97 {
98         mutex_unlock(&chrdevs_lock);
99         kfree(dev);
100 }
101
102
103 int count_chrdev_list(void)
104 {
105         struct char_device_struct *cd;
106         int i, count;
107
108         count = 0;
109
110         for (i = 0; i < ARRAY_SIZE(chrdevs) ; i++) {
111                 for (cd = chrdevs[i]; cd; cd = cd->next)
112                         count++;
113         }
114
115         return count;
116 }
117
118 int get_chrdev_info(void *dev, int *major, char **name)
119 {
120         struct chrdev_info *info = dev;
121
122         if (info->cd == NULL)
123                 return 1;
124
125         *major = info->cd->major;
126         *name = info->cd->name;
127         return 0;
128 }
129
130 /*
131  * Register a single major with a specified minor range.
132  *
133  * If major == 0 this functions will dynamically allocate a major and return
134  * its number.
135  *
136  * If major > 0 this function will attempt to reserve the passed range of
137  * minors and will return zero on success.
138  *
139  * Returns a -ve errno on failure.
140  */
141 static struct char_device_struct *
142 __register_chrdev_region(unsigned int major, unsigned int baseminor,
143                            int minorct, const char *name)
144 {
145         struct char_device_struct *cd, **cp;
146         int ret = 0;
147         int i;
148
149         cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
150         if (cd == NULL)
151                 return ERR_PTR(-ENOMEM);
152
153         mutex_lock(&chrdevs_lock);
154
155         /* temporary */
156         if (major == 0) {
157                 for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
158                         if (chrdevs[i] == NULL)
159                                 break;
160                 }
161
162                 if (i == 0) {
163                         ret = -EBUSY;
164                         goto out;
165                 }
166                 major = i;
167                 ret = major;
168         }
169
170         cd->major = major;
171         cd->baseminor = baseminor;
172         cd->minorct = minorct;
173         strncpy(cd->name,name, 64);
174
175         i = major_to_index(major);
176
177         for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
178                 if ((*cp)->major > major ||
179                     ((*cp)->major == major && (*cp)->baseminor >= baseminor))
180                         break;
181         if (*cp && (*cp)->major == major &&
182             (*cp)->baseminor < baseminor + minorct) {
183                 ret = -EBUSY;
184                 goto out;
185         }
186         cd->next = *cp;
187         *cp = cd;
188         mutex_unlock(&chrdevs_lock);
189         return cd;
190 out:
191         mutex_unlock(&chrdevs_lock);
192         kfree(cd);
193         return ERR_PTR(ret);
194 }
195
196 static struct char_device_struct *
197 __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
198 {
199         struct char_device_struct *cd = NULL, **cp;
200         int i = major_to_index(major);
201
202         mutex_lock(&chrdevs_lock);
203         for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
204                 if ((*cp)->major == major &&
205                     (*cp)->baseminor == baseminor &&
206                     (*cp)->minorct == minorct)
207                         break;
208         if (*cp) {
209                 cd = *cp;
210                 *cp = cd->next;
211         }
212         mutex_unlock(&chrdevs_lock);
213         return cd;
214 }
215
216 int register_chrdev_region(dev_t from, unsigned count, const char *name)
217 {
218         struct char_device_struct *cd;
219         dev_t to = from + count;
220         dev_t n, next;
221
222         for (n = from; n < to; n = next) {
223                 next = MKDEV(MAJOR(n)+1, 0);
224                 if (next > to)
225                         next = to;
226                 cd = __register_chrdev_region(MAJOR(n), MINOR(n),
227                                next - n, name);
228                 if (IS_ERR(cd))
229                         goto fail;
230         }
231         return 0;
232 fail:
233         to = n;
234         for (n = from; n < to; n = next) {
235                 next = MKDEV(MAJOR(n)+1, 0);
236                 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
237         }
238         return PTR_ERR(cd);
239 }
240
241 int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
242                         const char *name)
243 {
244         struct char_device_struct *cd;
245         cd = __register_chrdev_region(0, baseminor, count, name);
246         if (IS_ERR(cd))
247                 return PTR_ERR(cd);
248         *dev = MKDEV(cd->major, cd->baseminor);
249         return 0;
250 }
251
252 int register_chrdev(unsigned int major, const char *name,
253                     struct file_operations *fops)
254 {
255         struct char_device_struct *cd;
256         struct cdev *cdev;
257         char *s;
258         int err = -ENOMEM;
259
260         cd = __register_chrdev_region(major, 0, 256, name);
261         if (IS_ERR(cd))
262                 return PTR_ERR(cd);
263         
264         cdev = cdev_alloc();
265         if (!cdev)
266                 goto out2;
267
268         cdev->owner = fops->owner;
269         cdev->ops = fops;
270         kobject_set_name(&cdev->kobj, "%s", name);
271         for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
272                 *s = '!';
273                 
274         err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
275         if (err)
276                 goto out;
277
278         cd->cdev = cdev;
279
280         return major ? 0 : cd->major;
281 out:
282         kobject_put(&cdev->kobj);
283 out2:
284         kfree(__unregister_chrdev_region(cd->major, 0, 256));
285         return err;
286 }
287
288 void unregister_chrdev_region(dev_t from, unsigned count)
289 {
290         dev_t to = from + count;
291         dev_t n, next;
292
293         for (n = from; n < to; n = next) {
294                 next = MKDEV(MAJOR(n)+1, 0);
295                 if (next > to)
296                         next = to;
297                 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
298         }
299 }
300
301 int unregister_chrdev(unsigned int major, const char *name)
302 {
303         struct char_device_struct *cd;
304         cd = __unregister_chrdev_region(major, 0, 256);
305         if (cd && cd->cdev)
306                 cdev_del(cd->cdev);
307         kfree(cd);
308         return 0;
309 }
310
311 static DEFINE_SPINLOCK(cdev_lock);
312
313 static struct kobject *cdev_get(struct cdev *p)
314 {
315         struct module *owner = p->owner;
316         struct kobject *kobj;
317
318         if (owner && !try_module_get(owner))
319                 return NULL;
320         kobj = kobject_get(&p->kobj);
321         if (!kobj)
322                 module_put(owner);
323         return kobj;
324 }
325
326 void cdev_put(struct cdev *p)
327 {
328         if (p) {
329                 struct module *owner = p->owner;
330                 kobject_put(&p->kobj);
331                 module_put(owner);
332         }
333 }
334
335 /*
336  * Called every time a character special file is opened
337  */
338 int chrdev_open(struct inode * inode, struct file * filp)
339 {
340         struct cdev *p;
341         struct cdev *new = NULL;
342         int ret = 0;
343
344         spin_lock(&cdev_lock);
345         p = inode->i_cdev;
346         if (!p) {
347                 struct kobject *kobj;
348                 int idx;
349                 spin_unlock(&cdev_lock);
350                 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
351                 if (!kobj)
352                         return -ENXIO;
353                 new = container_of(kobj, struct cdev, kobj);
354                 spin_lock(&cdev_lock);
355                 p = inode->i_cdev;
356                 if (!p) {
357                         inode->i_cdev = p = new;
358                         inode->i_cindex = idx;
359                         list_add(&inode->i_devices, &p->list);
360                         new = NULL;
361                 } else if (!cdev_get(p))
362                         ret = -ENXIO;
363         } else if (!cdev_get(p))
364                 ret = -ENXIO;
365         spin_unlock(&cdev_lock);
366         cdev_put(new);
367         if (ret)
368                 return ret;
369         filp->f_op = fops_get(p->ops);
370         if (!filp->f_op) {
371                 cdev_put(p);
372                 return -ENXIO;
373         }
374         if (filp->f_op->open) {
375                 lock_kernel();
376                 ret = filp->f_op->open(inode,filp);
377                 unlock_kernel();
378         }
379         if (ret)
380                 cdev_put(p);
381         return ret;
382 }
383
384 void cd_forget(struct inode *inode)
385 {
386         spin_lock(&cdev_lock);
387         list_del_init(&inode->i_devices);
388         inode->i_cdev = NULL;
389         spin_unlock(&cdev_lock);
390 }
391
392 static void cdev_purge(struct cdev *cdev)
393 {
394         spin_lock(&cdev_lock);
395         while (!list_empty(&cdev->list)) {
396                 struct inode *inode;
397                 inode = container_of(cdev->list.next, struct inode, i_devices);
398                 list_del_init(&inode->i_devices);
399                 inode->i_cdev = NULL;
400         }
401         spin_unlock(&cdev_lock);
402 }
403
404 /*
405  * Dummy default file-operations: the only thing this does
406  * is contain the open that then fills in the correct operations
407  * depending on the special file...
408  */
409 struct file_operations def_chr_fops = {
410         .open = chrdev_open,
411 };
412
413 static struct kobject *exact_match(dev_t dev, int *part, void *data)
414 {
415         struct cdev *p = data;
416         return &p->kobj;
417 }
418
419 static int exact_lock(dev_t dev, void *data)
420 {
421         struct cdev *p = data;
422         return cdev_get(p) ? 0 : -1;
423 }
424
425 int cdev_add(struct cdev *p, dev_t dev, unsigned count)
426 {
427         p->dev = dev;
428         p->count = count;
429         return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
430 }
431
432 static void cdev_unmap(dev_t dev, unsigned count)
433 {
434         kobj_unmap(cdev_map, dev, count);
435 }
436
437 void cdev_del(struct cdev *p)
438 {
439         cdev_unmap(p->dev, p->count);
440         kobject_put(&p->kobj);
441 }
442
443
444 static void cdev_default_release(struct kobject *kobj)
445 {
446         struct cdev *p = container_of(kobj, struct cdev, kobj);
447         cdev_purge(p);
448 }
449
450 static void cdev_dynamic_release(struct kobject *kobj)
451 {
452         struct cdev *p = container_of(kobj, struct cdev, kobj);
453         cdev_purge(p);
454         kfree(p);
455 }
456
457 static struct kobj_type ktype_cdev_default = {
458         .release        = cdev_default_release,
459 };
460
461 static struct kobj_type ktype_cdev_dynamic = {
462         .release        = cdev_dynamic_release,
463 };
464
465 struct cdev *cdev_alloc(void)
466 {
467         struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
468         if (p) {
469                 p->kobj.ktype = &ktype_cdev_dynamic;
470                 INIT_LIST_HEAD(&p->list);
471                 kobject_init(&p->kobj);
472         }
473         return p;
474 }
475
476 void cdev_init(struct cdev *cdev, struct file_operations *fops)
477 {
478         memset(cdev, 0, sizeof *cdev);
479         INIT_LIST_HEAD(&cdev->list);
480         cdev->kobj.ktype = &ktype_cdev_default;
481         kobject_init(&cdev->kobj);
482         cdev->ops = fops;
483 }
484
485 static struct kobject *base_probe(dev_t dev, int *part, void *data)
486 {
487         if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
488                 /* Make old-style 2.4 aliases work */
489                 request_module("char-major-%d", MAJOR(dev));
490         return NULL;
491 }
492
493 void __init chrdev_init(void)
494 {
495         cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
496 }
497
498
499 /* Let modules do char dev stuff */
500 EXPORT_SYMBOL(register_chrdev_region);
501 EXPORT_SYMBOL(unregister_chrdev_region);
502 EXPORT_SYMBOL(alloc_chrdev_region);
503 EXPORT_SYMBOL(cdev_init);
504 EXPORT_SYMBOL(cdev_alloc);
505 EXPORT_SYMBOL(cdev_del);
506 EXPORT_SYMBOL(cdev_add);
507 EXPORT_SYMBOL(register_chrdev);
508 EXPORT_SYMBOL(unregister_chrdev);