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1da177e4 LT |
1 | /* |
2 | * kobject.c - library routines for handling generic kernel objects | |
3 | * | |
4 | * Copyright (c) 2002-2003 Patrick Mochel <mochel@osdl.org> | |
5 | * | |
6 | * This file is released under the GPLv2. | |
7 | * | |
8 | * | |
9 | * Please see the file Documentation/kobject.txt for critical information | |
10 | * about using the kobject interface. | |
11 | */ | |
12 | ||
13 | #include <linux/kobject.h> | |
14 | #include <linux/string.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/stat.h> | |
17 | ||
18 | /** | |
19 | * populate_dir - populate directory with attributes. | |
20 | * @kobj: object we're working on. | |
21 | * | |
22 | * Most subsystems have a set of default attributes that | |
23 | * are associated with an object that registers with them. | |
24 | * This is a helper called during object registration that | |
25 | * loops through the default attributes of the subsystem | |
26 | * and creates attributes files for them in sysfs. | |
27 | * | |
28 | */ | |
29 | ||
30 | static int populate_dir(struct kobject * kobj) | |
31 | { | |
32 | struct kobj_type * t = get_ktype(kobj); | |
33 | struct attribute * attr; | |
34 | int error = 0; | |
35 | int i; | |
36 | ||
37 | if (t && t->default_attrs) { | |
38 | for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) { | |
39 | if ((error = sysfs_create_file(kobj,attr))) | |
40 | break; | |
41 | } | |
42 | } | |
43 | return error; | |
44 | } | |
45 | ||
46 | static int create_dir(struct kobject * kobj) | |
47 | { | |
48 | int error = 0; | |
49 | if (kobject_name(kobj)) { | |
50 | error = sysfs_create_dir(kobj); | |
51 | if (!error) { | |
52 | if ((error = populate_dir(kobj))) | |
53 | sysfs_remove_dir(kobj); | |
54 | } | |
55 | } | |
56 | return error; | |
57 | } | |
58 | ||
59 | static inline struct kobject * to_kobj(struct list_head * entry) | |
60 | { | |
61 | return container_of(entry,struct kobject,entry); | |
62 | } | |
63 | ||
64 | static int get_kobj_path_length(struct kobject *kobj) | |
65 | { | |
66 | int length = 1; | |
67 | struct kobject * parent = kobj; | |
68 | ||
69 | /* walk up the ancestors until we hit the one pointing to the | |
70 | * root. | |
71 | * Add 1 to strlen for leading '/' of each level. | |
72 | */ | |
73 | do { | |
74 | length += strlen(kobject_name(parent)) + 1; | |
75 | parent = parent->parent; | |
76 | } while (parent); | |
77 | return length; | |
78 | } | |
79 | ||
80 | static void fill_kobj_path(struct kobject *kobj, char *path, int length) | |
81 | { | |
82 | struct kobject * parent; | |
83 | ||
84 | --length; | |
85 | for (parent = kobj; parent; parent = parent->parent) { | |
86 | int cur = strlen(kobject_name(parent)); | |
87 | /* back up enough to print this name with '/' */ | |
88 | length -= cur; | |
89 | strncpy (path + length, kobject_name(parent), cur); | |
90 | *(path + --length) = '/'; | |
91 | } | |
92 | ||
93 | pr_debug("%s: path = '%s'\n",__FUNCTION__,path); | |
94 | } | |
95 | ||
96 | /** | |
97 | * kobject_get_path - generate and return the path associated with a given kobj | |
98 | * and kset pair. The result must be freed by the caller with kfree(). | |
99 | * | |
100 | * @kobj: kobject in question, with which to build the path | |
101 | * @gfp_mask: the allocation type used to allocate the path | |
102 | */ | |
103 | char *kobject_get_path(struct kobject *kobj, int gfp_mask) | |
104 | { | |
105 | char *path; | |
106 | int len; | |
107 | ||
108 | len = get_kobj_path_length(kobj); | |
109 | path = kmalloc(len, gfp_mask); | |
110 | if (!path) | |
111 | return NULL; | |
112 | memset(path, 0x00, len); | |
113 | fill_kobj_path(kobj, path, len); | |
114 | ||
115 | return path; | |
116 | } | |
117 | ||
118 | /** | |
119 | * kobject_init - initialize object. | |
120 | * @kobj: object in question. | |
121 | */ | |
122 | void kobject_init(struct kobject * kobj) | |
123 | { | |
124 | kref_init(&kobj->kref); | |
125 | INIT_LIST_HEAD(&kobj->entry); | |
126 | kobj->kset = kset_get(kobj->kset); | |
127 | } | |
128 | ||
129 | ||
130 | /** | |
131 | * unlink - remove kobject from kset list. | |
132 | * @kobj: kobject. | |
133 | * | |
134 | * Remove the kobject from the kset list and decrement | |
135 | * its parent's refcount. | |
136 | * This is separated out, so we can use it in both | |
137 | * kobject_del() and kobject_add() on error. | |
138 | */ | |
139 | ||
140 | static void unlink(struct kobject * kobj) | |
141 | { | |
142 | if (kobj->kset) { | |
143 | spin_lock(&kobj->kset->list_lock); | |
144 | list_del_init(&kobj->entry); | |
145 | spin_unlock(&kobj->kset->list_lock); | |
146 | } | |
147 | kobject_put(kobj); | |
148 | } | |
149 | ||
150 | /** | |
151 | * kobject_add - add an object to the hierarchy. | |
152 | * @kobj: object. | |
153 | */ | |
154 | ||
155 | int kobject_add(struct kobject * kobj) | |
156 | { | |
157 | int error = 0; | |
158 | struct kobject * parent; | |
159 | ||
160 | if (!(kobj = kobject_get(kobj))) | |
161 | return -ENOENT; | |
162 | if (!kobj->k_name) | |
163 | kobj->k_name = kobj->name; | |
164 | parent = kobject_get(kobj->parent); | |
165 | ||
166 | pr_debug("kobject %s: registering. parent: %s, set: %s\n", | |
167 | kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>", | |
168 | kobj->kset ? kobj->kset->kobj.name : "<NULL>" ); | |
169 | ||
170 | if (kobj->kset) { | |
171 | spin_lock(&kobj->kset->list_lock); | |
172 | ||
173 | if (!parent) | |
174 | parent = kobject_get(&kobj->kset->kobj); | |
175 | ||
176 | list_add_tail(&kobj->entry,&kobj->kset->list); | |
177 | spin_unlock(&kobj->kset->list_lock); | |
178 | } | |
179 | kobj->parent = parent; | |
180 | ||
181 | error = create_dir(kobj); | |
182 | if (error) { | |
183 | /* unlink does the kobject_put() for us */ | |
184 | unlink(kobj); | |
185 | if (parent) | |
186 | kobject_put(parent); | |
187 | } else { | |
188 | kobject_hotplug(kobj, KOBJ_ADD); | |
189 | } | |
190 | ||
191 | return error; | |
192 | } | |
193 | ||
194 | ||
195 | /** | |
196 | * kobject_register - initialize and add an object. | |
197 | * @kobj: object in question. | |
198 | */ | |
199 | ||
200 | int kobject_register(struct kobject * kobj) | |
201 | { | |
202 | int error = 0; | |
203 | if (kobj) { | |
204 | kobject_init(kobj); | |
205 | error = kobject_add(kobj); | |
206 | if (error) { | |
207 | printk("kobject_register failed for %s (%d)\n", | |
208 | kobject_name(kobj),error); | |
209 | dump_stack(); | |
210 | } | |
211 | } else | |
212 | error = -EINVAL; | |
213 | return error; | |
214 | } | |
215 | ||
216 | ||
217 | /** | |
218 | * kobject_set_name - Set the name of an object | |
219 | * @kobj: object. | |
220 | * @name: name. | |
221 | * | |
222 | * If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated | |
223 | * string that @kobj->k_name points to. Otherwise, use the static | |
224 | * @kobj->name array. | |
225 | */ | |
226 | ||
227 | int kobject_set_name(struct kobject * kobj, const char * fmt, ...) | |
228 | { | |
229 | int error = 0; | |
230 | int limit = KOBJ_NAME_LEN; | |
231 | int need; | |
232 | va_list args; | |
233 | char * name; | |
234 | ||
235 | /* | |
236 | * First, try the static array | |
237 | */ | |
238 | va_start(args,fmt); | |
239 | need = vsnprintf(kobj->name,limit,fmt,args); | |
240 | va_end(args); | |
241 | if (need < limit) | |
242 | name = kobj->name; | |
243 | else { | |
244 | /* | |
245 | * Need more space? Allocate it and try again | |
246 | */ | |
247 | limit = need + 1; | |
248 | name = kmalloc(limit,GFP_KERNEL); | |
249 | if (!name) { | |
250 | error = -ENOMEM; | |
251 | goto Done; | |
252 | } | |
253 | va_start(args,fmt); | |
254 | need = vsnprintf(name,limit,fmt,args); | |
255 | va_end(args); | |
256 | ||
257 | /* Still? Give up. */ | |
258 | if (need >= limit) { | |
259 | kfree(name); | |
260 | error = -EFAULT; | |
261 | goto Done; | |
262 | } | |
263 | } | |
264 | ||
265 | /* Free the old name, if necessary. */ | |
266 | if (kobj->k_name && kobj->k_name != kobj->name) | |
267 | kfree(kobj->k_name); | |
268 | ||
269 | /* Now, set the new name */ | |
270 | kobj->k_name = name; | |
271 | Done: | |
272 | return error; | |
273 | } | |
274 | ||
275 | EXPORT_SYMBOL(kobject_set_name); | |
276 | ||
277 | ||
278 | /** | |
279 | * kobject_rename - change the name of an object | |
280 | * @kobj: object in question. | |
281 | * @new_name: object's new name | |
282 | */ | |
283 | ||
284 | int kobject_rename(struct kobject * kobj, char *new_name) | |
285 | { | |
286 | int error = 0; | |
287 | ||
288 | kobj = kobject_get(kobj); | |
289 | if (!kobj) | |
290 | return -EINVAL; | |
291 | error = sysfs_rename_dir(kobj, new_name); | |
292 | kobject_put(kobj); | |
293 | ||
294 | return error; | |
295 | } | |
296 | ||
297 | /** | |
298 | * kobject_del - unlink kobject from hierarchy. | |
299 | * @kobj: object. | |
300 | */ | |
301 | ||
302 | void kobject_del(struct kobject * kobj) | |
303 | { | |
304 | kobject_hotplug(kobj, KOBJ_REMOVE); | |
305 | sysfs_remove_dir(kobj); | |
306 | unlink(kobj); | |
307 | } | |
308 | ||
309 | /** | |
310 | * kobject_unregister - remove object from hierarchy and decrement refcount. | |
311 | * @kobj: object going away. | |
312 | */ | |
313 | ||
314 | void kobject_unregister(struct kobject * kobj) | |
315 | { | |
316 | pr_debug("kobject %s: unregistering\n",kobject_name(kobj)); | |
317 | kobject_del(kobj); | |
318 | kobject_put(kobj); | |
319 | } | |
320 | ||
321 | /** | |
322 | * kobject_get - increment refcount for object. | |
323 | * @kobj: object. | |
324 | */ | |
325 | ||
326 | struct kobject * kobject_get(struct kobject * kobj) | |
327 | { | |
328 | if (kobj) | |
329 | kref_get(&kobj->kref); | |
330 | return kobj; | |
331 | } | |
332 | ||
333 | /** | |
334 | * kobject_cleanup - free kobject resources. | |
335 | * @kobj: object. | |
336 | */ | |
337 | ||
338 | void kobject_cleanup(struct kobject * kobj) | |
339 | { | |
340 | struct kobj_type * t = get_ktype(kobj); | |
341 | struct kset * s = kobj->kset; | |
342 | struct kobject * parent = kobj->parent; | |
343 | ||
344 | pr_debug("kobject %s: cleaning up\n",kobject_name(kobj)); | |
345 | if (kobj->k_name != kobj->name) | |
346 | kfree(kobj->k_name); | |
347 | kobj->k_name = NULL; | |
348 | if (t && t->release) | |
349 | t->release(kobj); | |
350 | if (s) | |
351 | kset_put(s); | |
352 | if (parent) | |
353 | kobject_put(parent); | |
354 | } | |
355 | ||
356 | static void kobject_release(struct kref *kref) | |
357 | { | |
358 | kobject_cleanup(container_of(kref, struct kobject, kref)); | |
359 | } | |
360 | ||
361 | /** | |
362 | * kobject_put - decrement refcount for object. | |
363 | * @kobj: object. | |
364 | * | |
365 | * Decrement the refcount, and if 0, call kobject_cleanup(). | |
366 | */ | |
367 | void kobject_put(struct kobject * kobj) | |
368 | { | |
369 | if (kobj) | |
370 | kref_put(&kobj->kref, kobject_release); | |
371 | } | |
372 | ||
373 | ||
374 | /** | |
375 | * kset_init - initialize a kset for use | |
376 | * @k: kset | |
377 | */ | |
378 | ||
379 | void kset_init(struct kset * k) | |
380 | { | |
381 | kobject_init(&k->kobj); | |
382 | INIT_LIST_HEAD(&k->list); | |
383 | spin_lock_init(&k->list_lock); | |
384 | } | |
385 | ||
386 | ||
387 | /** | |
388 | * kset_add - add a kset object to the hierarchy. | |
389 | * @k: kset. | |
390 | * | |
391 | * Simply, this adds the kset's embedded kobject to the | |
392 | * hierarchy. | |
393 | * We also try to make sure that the kset's embedded kobject | |
394 | * has a parent before it is added. We only care if the embedded | |
395 | * kobject is not part of a kset itself, since kobject_add() | |
396 | * assigns a parent in that case. | |
397 | * If that is the case, and the kset has a controlling subsystem, | |
398 | * then we set the kset's parent to be said subsystem. | |
399 | */ | |
400 | ||
401 | int kset_add(struct kset * k) | |
402 | { | |
403 | if (!k->kobj.parent && !k->kobj.kset && k->subsys) | |
404 | k->kobj.parent = &k->subsys->kset.kobj; | |
405 | ||
406 | return kobject_add(&k->kobj); | |
407 | } | |
408 | ||
409 | ||
410 | /** | |
411 | * kset_register - initialize and add a kset. | |
412 | * @k: kset. | |
413 | */ | |
414 | ||
415 | int kset_register(struct kset * k) | |
416 | { | |
417 | kset_init(k); | |
418 | return kset_add(k); | |
419 | } | |
420 | ||
421 | ||
422 | /** | |
423 | * kset_unregister - remove a kset. | |
424 | * @k: kset. | |
425 | */ | |
426 | ||
427 | void kset_unregister(struct kset * k) | |
428 | { | |
429 | kobject_unregister(&k->kobj); | |
430 | } | |
431 | ||
432 | ||
433 | /** | |
434 | * kset_find_obj - search for object in kset. | |
435 | * @kset: kset we're looking in. | |
436 | * @name: object's name. | |
437 | * | |
438 | * Lock kset via @kset->subsys, and iterate over @kset->list, | |
439 | * looking for a matching kobject. If matching object is found | |
440 | * take a reference and return the object. | |
441 | */ | |
442 | ||
443 | struct kobject * kset_find_obj(struct kset * kset, const char * name) | |
444 | { | |
445 | struct list_head * entry; | |
446 | struct kobject * ret = NULL; | |
447 | ||
448 | spin_lock(&kset->list_lock); | |
449 | list_for_each(entry,&kset->list) { | |
450 | struct kobject * k = to_kobj(entry); | |
451 | if (kobject_name(k) && !strcmp(kobject_name(k),name)) { | |
452 | ret = kobject_get(k); | |
453 | break; | |
454 | } | |
455 | } | |
456 | spin_unlock(&kset->list_lock); | |
457 | return ret; | |
458 | } | |
459 | ||
460 | ||
461 | void subsystem_init(struct subsystem * s) | |
462 | { | |
463 | init_rwsem(&s->rwsem); | |
464 | kset_init(&s->kset); | |
465 | } | |
466 | ||
467 | /** | |
468 | * subsystem_register - register a subsystem. | |
469 | * @s: the subsystem we're registering. | |
470 | * | |
471 | * Once we register the subsystem, we want to make sure that | |
472 | * the kset points back to this subsystem for correct usage of | |
473 | * the rwsem. | |
474 | */ | |
475 | ||
476 | int subsystem_register(struct subsystem * s) | |
477 | { | |
478 | int error; | |
479 | ||
480 | subsystem_init(s); | |
481 | pr_debug("subsystem %s: registering\n",s->kset.kobj.name); | |
482 | ||
483 | if (!(error = kset_add(&s->kset))) { | |
484 | if (!s->kset.subsys) | |
485 | s->kset.subsys = s; | |
486 | } | |
487 | return error; | |
488 | } | |
489 | ||
490 | void subsystem_unregister(struct subsystem * s) | |
491 | { | |
492 | pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name); | |
493 | kset_unregister(&s->kset); | |
494 | } | |
495 | ||
496 | ||
497 | /** | |
498 | * subsystem_create_file - export sysfs attribute file. | |
499 | * @s: subsystem. | |
500 | * @a: subsystem attribute descriptor. | |
501 | */ | |
502 | ||
503 | int subsys_create_file(struct subsystem * s, struct subsys_attribute * a) | |
504 | { | |
505 | int error = 0; | |
506 | if (subsys_get(s)) { | |
507 | error = sysfs_create_file(&s->kset.kobj,&a->attr); | |
508 | subsys_put(s); | |
509 | } | |
510 | return error; | |
511 | } | |
512 | ||
513 | ||
514 | /** | |
515 | * subsystem_remove_file - remove sysfs attribute file. | |
516 | * @s: subsystem. | |
517 | * @a: attribute desciptor. | |
518 | */ | |
519 | ||
520 | void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a) | |
521 | { | |
522 | if (subsys_get(s)) { | |
523 | sysfs_remove_file(&s->kset.kobj,&a->attr); | |
524 | subsys_put(s); | |
525 | } | |
526 | } | |
527 | ||
528 | EXPORT_SYMBOL(kobject_init); | |
529 | EXPORT_SYMBOL(kobject_register); | |
530 | EXPORT_SYMBOL(kobject_unregister); | |
531 | EXPORT_SYMBOL(kobject_get); | |
532 | EXPORT_SYMBOL(kobject_put); | |
533 | EXPORT_SYMBOL(kobject_add); | |
534 | EXPORT_SYMBOL(kobject_del); | |
535 | ||
536 | EXPORT_SYMBOL(kset_register); | |
537 | EXPORT_SYMBOL(kset_unregister); | |
538 | EXPORT_SYMBOL(kset_find_obj); | |
539 | ||
540 | EXPORT_SYMBOL(subsystem_init); | |
541 | EXPORT_SYMBOL(subsystem_register); | |
542 | EXPORT_SYMBOL(subsystem_unregister); | |
543 | EXPORT_SYMBOL(subsys_create_file); | |
544 | EXPORT_SYMBOL(subsys_remove_file); |