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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
30static 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
46static 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
59static inline struct kobject * to_kobj(struct list_head * entry)
60{
61 return container_of(entry,struct kobject,entry);
62}
63
64static 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
80static 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 */
103char *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 */
122void 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
140static 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
155int 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);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 }
188
189 return error;
190}
191
192
193/**
194 * kobject_register - initialize and add an object.
195 * @kobj: object in question.
196 */
197
198int kobject_register(struct kobject * kobj)
199{
200 int error = 0;
201 if (kobj) {
202 kobject_init(kobj);
203 error = kobject_add(kobj);
204 if (error) {
205 printk("kobject_register failed for %s (%d)\n",
206 kobject_name(kobj),error);
207 dump_stack();
kay.sievers@vrfy.org18c3d522005-04-18 21:57:34 -0700208 } else
209 kobject_hotplug(kobj, KOBJ_ADD);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 } else
211 error = -EINVAL;
212 return error;
213}
214
215
216/**
217 * kobject_set_name - Set the name of an object
218 * @kobj: object.
219 * @name: name.
220 *
221 * If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
222 * string that @kobj->k_name points to. Otherwise, use the static
223 * @kobj->name array.
224 */
225
226int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
227{
228 int error = 0;
229 int limit = KOBJ_NAME_LEN;
230 int need;
231 va_list args;
232 char * name;
233
234 /*
235 * First, try the static array
236 */
237 va_start(args,fmt);
238 need = vsnprintf(kobj->name,limit,fmt,args);
239 va_end(args);
240 if (need < limit)
241 name = kobj->name;
242 else {
243 /*
244 * Need more space? Allocate it and try again
245 */
246 limit = need + 1;
247 name = kmalloc(limit,GFP_KERNEL);
248 if (!name) {
249 error = -ENOMEM;
250 goto Done;
251 }
252 va_start(args,fmt);
253 need = vsnprintf(name,limit,fmt,args);
254 va_end(args);
255
256 /* Still? Give up. */
257 if (need >= limit) {
258 kfree(name);
259 error = -EFAULT;
260 goto Done;
261 }
262 }
263
264 /* Free the old name, if necessary. */
265 if (kobj->k_name && kobj->k_name != kobj->name)
266 kfree(kobj->k_name);
267
268 /* Now, set the new name */
269 kobj->k_name = name;
270 Done:
271 return error;
272}
273
274EXPORT_SYMBOL(kobject_set_name);
275
276
277/**
278 * kobject_rename - change the name of an object
279 * @kobj: object in question.
280 * @new_name: object's new name
281 */
282
283int kobject_rename(struct kobject * kobj, char *new_name)
284{
285 int error = 0;
286
287 kobj = kobject_get(kobj);
288 if (!kobj)
289 return -EINVAL;
290 error = sysfs_rename_dir(kobj, new_name);
291 kobject_put(kobj);
292
293 return error;
294}
295
296/**
297 * kobject_del - unlink kobject from hierarchy.
298 * @kobj: object.
299 */
300
301void kobject_del(struct kobject * kobj)
302{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 sysfs_remove_dir(kobj);
304 unlink(kobj);
305}
306
307/**
308 * kobject_unregister - remove object from hierarchy and decrement refcount.
309 * @kobj: object going away.
310 */
311
312void kobject_unregister(struct kobject * kobj)
313{
314 pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
kay.sievers@vrfy.org18c3d522005-04-18 21:57:34 -0700315 kobject_hotplug(kobj, KOBJ_REMOVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 kobject_del(kobj);
317 kobject_put(kobj);
318}
319
320/**
321 * kobject_get - increment refcount for object.
322 * @kobj: object.
323 */
324
325struct kobject * kobject_get(struct kobject * kobj)
326{
327 if (kobj)
328 kref_get(&kobj->kref);
329 return kobj;
330}
331
332/**
333 * kobject_cleanup - free kobject resources.
334 * @kobj: object.
335 */
336
337void kobject_cleanup(struct kobject * kobj)
338{
339 struct kobj_type * t = get_ktype(kobj);
340 struct kset * s = kobj->kset;
341 struct kobject * parent = kobj->parent;
342
343 pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
344 if (kobj->k_name != kobj->name)
345 kfree(kobj->k_name);
346 kobj->k_name = NULL;
347 if (t && t->release)
348 t->release(kobj);
349 if (s)
350 kset_put(s);
351 if (parent)
352 kobject_put(parent);
353}
354
355static void kobject_release(struct kref *kref)
356{
357 kobject_cleanup(container_of(kref, struct kobject, kref));
358}
359
360/**
361 * kobject_put - decrement refcount for object.
362 * @kobj: object.
363 *
364 * Decrement the refcount, and if 0, call kobject_cleanup().
365 */
366void kobject_put(struct kobject * kobj)
367{
368 if (kobj)
369 kref_put(&kobj->kref, kobject_release);
370}
371
372
373/**
374 * kset_init - initialize a kset for use
375 * @k: kset
376 */
377
378void kset_init(struct kset * k)
379{
380 kobject_init(&k->kobj);
381 INIT_LIST_HEAD(&k->list);
382 spin_lock_init(&k->list_lock);
383}
384
385
386/**
387 * kset_add - add a kset object to the hierarchy.
388 * @k: kset.
389 *
390 * Simply, this adds the kset's embedded kobject to the
391 * hierarchy.
392 * We also try to make sure that the kset's embedded kobject
393 * has a parent before it is added. We only care if the embedded
394 * kobject is not part of a kset itself, since kobject_add()
395 * assigns a parent in that case.
396 * If that is the case, and the kset has a controlling subsystem,
397 * then we set the kset's parent to be said subsystem.
398 */
399
400int kset_add(struct kset * k)
401{
402 if (!k->kobj.parent && !k->kobj.kset && k->subsys)
403 k->kobj.parent = &k->subsys->kset.kobj;
404
405 return kobject_add(&k->kobj);
406}
407
408
409/**
410 * kset_register - initialize and add a kset.
411 * @k: kset.
412 */
413
414int kset_register(struct kset * k)
415{
416 kset_init(k);
417 return kset_add(k);
418}
419
420
421/**
422 * kset_unregister - remove a kset.
423 * @k: kset.
424 */
425
426void kset_unregister(struct kset * k)
427{
428 kobject_unregister(&k->kobj);
429}
430
431
432/**
433 * kset_find_obj - search for object in kset.
434 * @kset: kset we're looking in.
435 * @name: object's name.
436 *
437 * Lock kset via @kset->subsys, and iterate over @kset->list,
438 * looking for a matching kobject. If matching object is found
439 * take a reference and return the object.
440 */
441
442struct kobject * kset_find_obj(struct kset * kset, const char * name)
443{
444 struct list_head * entry;
445 struct kobject * ret = NULL;
446
447 spin_lock(&kset->list_lock);
448 list_for_each(entry,&kset->list) {
449 struct kobject * k = to_kobj(entry);
450 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
451 ret = kobject_get(k);
452 break;
453 }
454 }
455 spin_unlock(&kset->list_lock);
456 return ret;
457}
458
459
460void subsystem_init(struct subsystem * s)
461{
462 init_rwsem(&s->rwsem);
463 kset_init(&s->kset);
464}
465
466/**
467 * subsystem_register - register a subsystem.
468 * @s: the subsystem we're registering.
469 *
470 * Once we register the subsystem, we want to make sure that
471 * the kset points back to this subsystem for correct usage of
472 * the rwsem.
473 */
474
475int subsystem_register(struct subsystem * s)
476{
477 int error;
478
479 subsystem_init(s);
480 pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
481
482 if (!(error = kset_add(&s->kset))) {
483 if (!s->kset.subsys)
484 s->kset.subsys = s;
485 }
486 return error;
487}
488
489void subsystem_unregister(struct subsystem * s)
490{
491 pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
492 kset_unregister(&s->kset);
493}
494
495
496/**
497 * subsystem_create_file - export sysfs attribute file.
498 * @s: subsystem.
499 * @a: subsystem attribute descriptor.
500 */
501
502int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
503{
504 int error = 0;
505 if (subsys_get(s)) {
506 error = sysfs_create_file(&s->kset.kobj,&a->attr);
507 subsys_put(s);
508 }
509 return error;
510}
511
512
513/**
514 * subsystem_remove_file - remove sysfs attribute file.
515 * @s: subsystem.
516 * @a: attribute desciptor.
517 */
518
519void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
520{
521 if (subsys_get(s)) {
522 sysfs_remove_file(&s->kset.kobj,&a->attr);
523 subsys_put(s);
524 }
525}
526
527EXPORT_SYMBOL(kobject_init);
528EXPORT_SYMBOL(kobject_register);
529EXPORT_SYMBOL(kobject_unregister);
530EXPORT_SYMBOL(kobject_get);
531EXPORT_SYMBOL(kobject_put);
532EXPORT_SYMBOL(kobject_add);
533EXPORT_SYMBOL(kobject_del);
534
535EXPORT_SYMBOL(kset_register);
536EXPORT_SYMBOL(kset_unregister);
537EXPORT_SYMBOL(kset_find_obj);
538
539EXPORT_SYMBOL(subsystem_init);
540EXPORT_SYMBOL(subsystem_register);
541EXPORT_SYMBOL(subsystem_unregister);
542EXPORT_SYMBOL(subsys_create_file);
543EXPORT_SYMBOL(subsys_remove_file);