projects/linux·blob v2.6.13 · refs

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1/*
2 * kobject.c - library routines for handling generic kernel objects
3 *
4 * Copyright (c) 2002-2003 Patrick Mochel <[email protected]>
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);
187 }
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();
208 } else
209 kobject_hotplug(kobj, KOBJ_ADD);
210 } 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 * @fmt: format string used to build the 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 */
225int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
226{
227 int error = 0;
228 int limit = KOBJ_NAME_LEN;
229 int need;
230 va_list args;
231 char * name;
232
233 /*
234 * First, try the static array
235 */
236 va_start(args,fmt);
237 need = vsnprintf(kobj->name,limit,fmt,args);
238 va_end(args);
239 if (need < limit)
240 name = kobj->name;
241 else {
242 /*
243 * Need more space? Allocate it and try again
244 */
245 limit = need + 1;
246 name = kmalloc(limit,GFP_KERNEL);
247 if (!name) {
248 error = -ENOMEM;
249 goto Done;
250 }
251 va_start(args,fmt);
252 need = vsnprintf(name,limit,fmt,args);
253 va_end(args);
254
255 /* Still? Give up. */
256 if (need >= limit) {
257 kfree(name);
258 error = -EFAULT;
259 goto Done;
260 }
261 }
262
263 /* Free the old name, if necessary. */
264 if (kobj->k_name && kobj->k_name != kobj->name)
265 kfree(kobj->k_name);
266
267 /* Now, set the new name */
268 kobj->k_name = name;
269 Done:
270 return error;
271}
272
273EXPORT_SYMBOL(kobject_set_name);
274
275
276/**
277 * kobject_rename - change the name of an object
278 * @kobj: object in question.
279 * @new_name: object's new name
280 */
281
282int kobject_rename(struct kobject * kobj, const char *new_name)
283{
284 int error = 0;
285
286 kobj = kobject_get(kobj);
287 if (!kobj)
288 return -EINVAL;
289 error = sysfs_rename_dir(kobj, new_name);
290 kobject_put(kobj);
291
292 return error;
293}
294
295/**
296 * kobject_del - unlink kobject from hierarchy.
297 * @kobj: object.
298 */
299
300void kobject_del(struct kobject * kobj)
301{
302 sysfs_remove_dir(kobj);
303 unlink(kobj);
304}
305
306/**
307 * kobject_unregister - remove object from hierarchy and decrement refcount.
308 * @kobj: object going away.
309 */
310
311void kobject_unregister(struct kobject * kobj)
312{
313 pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
314 kobject_hotplug(kobj, KOBJ_REMOVE);
315 kobject_del(kobj);
316 kobject_put(kobj);
317}
318
319/**
320 * kobject_get - increment refcount for object.
321 * @kobj: object.
322 */
323
324struct kobject * kobject_get(struct kobject * kobj)
325{
326 if (kobj)
327 kref_get(&kobj->kref);
328 return kobj;
329}
330
331/**
332 * kobject_cleanup - free kobject resources.
333 * @kobj: object.
334 */
335
336void kobject_cleanup(struct kobject * kobj)
337{
338 struct kobj_type * t = get_ktype(kobj);
339 struct kset * s = kobj->kset;
340 struct kobject * parent = kobj->parent;
341
342 pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
343 if (kobj->k_name != kobj->name)
344 kfree(kobj->k_name);
345 kobj->k_name = NULL;
346 if (t && t->release)
347 t->release(kobj);
348 if (s)
349 kset_put(s);
350 if (parent)
351 kobject_put(parent);
352}
353
354static void kobject_release(struct kref *kref)
355{
356 kobject_cleanup(container_of(kref, struct kobject, kref));
357}
358
359/**
360 * kobject_put - decrement refcount for object.
361 * @kobj: object.
362 *
363 * Decrement the refcount, and if 0, call kobject_cleanup().
364 */
365void kobject_put(struct kobject * kobj)
366{
367 if (kobj)
368 kref_put(&kobj->kref, kobject_release);
369}
370
371
372/**
373 * kset_init - initialize a kset for use
374 * @k: kset
375 */
376
377void kset_init(struct kset * k)
378{
379 kobject_init(&k->kobj);
380 INIT_LIST_HEAD(&k->list);
381 spin_lock_init(&k->list_lock);
382}
383
384
385/**
386 * kset_add - add a kset object to the hierarchy.
387 * @k: kset.
388 *
389 * Simply, this adds the kset's embedded kobject to the
390 * hierarchy.
391 * We also try to make sure that the kset's embedded kobject
392 * has a parent before it is added. We only care if the embedded
393 * kobject is not part of a kset itself, since kobject_add()
394 * assigns a parent in that case.
395 * If that is the case, and the kset has a controlling subsystem,
396 * then we set the kset's parent to be said subsystem.
397 */
398
399int kset_add(struct kset * k)
400{
401 if (!k->kobj.parent && !k->kobj.kset && k->subsys)
402 k->kobj.parent = &k->subsys->kset.kobj;
403
404 return kobject_add(&k->kobj);
405}
406
407
408/**
409 * kset_register - initialize and add a kset.
410 * @k: kset.
411 */
412
413int kset_register(struct kset * k)
414{
415 kset_init(k);
416 return kset_add(k);
417}
418
419
420/**
421 * kset_unregister - remove a kset.
422 * @k: kset.
423 */
424
425void kset_unregister(struct kset * k)
426{
427 kobject_unregister(&k->kobj);
428}
429
430
431/**
432 * kset_find_obj - search for object in kset.
433 * @kset: kset we're looking in.
434 * @name: object's name.
435 *
436 * Lock kset via @kset->subsys, and iterate over @kset->list,
437 * looking for a matching kobject. If matching object is found
438 * take a reference and return the object.
439 */
440
441struct kobject * kset_find_obj(struct kset * kset, const char * name)
442{
443 struct list_head * entry;
444 struct kobject * ret = NULL;
445
446 spin_lock(&kset->list_lock);
447 list_for_each(entry,&kset->list) {
448 struct kobject * k = to_kobj(entry);
449 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
450 ret = kobject_get(k);
451 break;
452 }
453 }
454 spin_unlock(&kset->list_lock);
455 return ret;
456}
457
458
459void subsystem_init(struct subsystem * s)
460{
461 init_rwsem(&s->rwsem);
462 kset_init(&s->kset);
463}
464
465/**
466 * subsystem_register - register a subsystem.
467 * @s: the subsystem we're registering.
468 *
469 * Once we register the subsystem, we want to make sure that
470 * the kset points back to this subsystem for correct usage of
471 * the rwsem.
472 */
473
474int subsystem_register(struct subsystem * s)
475{
476 int error;
477
478 subsystem_init(s);
479 pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
480
481 if (!(error = kset_add(&s->kset))) {
482 if (!s->kset.subsys)
483 s->kset.subsys = s;
484 }
485 return error;
486}
487
488void subsystem_unregister(struct subsystem * s)
489{
490 pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
491 kset_unregister(&s->kset);
492}
493
494
495/**
496 * subsystem_create_file - export sysfs attribute file.
497 * @s: subsystem.
498 * @a: subsystem attribute descriptor.
499 */
500
501int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
502{
503 int error = 0;
504 if (subsys_get(s)) {
505 error = sysfs_create_file(&s->kset.kobj,&a->attr);
506 subsys_put(s);
507 }
508 return error;
509}
510
511
512/**
513 * subsystem_remove_file - remove sysfs attribute file.
514 * @s: subsystem.
515 * @a: attribute desciptor.
516 */
517
518void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
519{
520 if (subsys_get(s)) {
521 sysfs_remove_file(&s->kset.kobj,&a->attr);
522 subsys_put(s);
523 }
524}
525
526EXPORT_SYMBOL(kobject_init);
527EXPORT_SYMBOL(kobject_register);
528EXPORT_SYMBOL(kobject_unregister);
529EXPORT_SYMBOL(kobject_get);
530EXPORT_SYMBOL(kobject_put);
531EXPORT_SYMBOL(kobject_add);
532EXPORT_SYMBOL(kobject_del);
533
534EXPORT_SYMBOL(kset_register);
535EXPORT_SYMBOL(kset_unregister);
536EXPORT_SYMBOL(kset_find_obj);
537
538EXPORT_SYMBOL(subsystem_init);
539EXPORT_SYMBOL(subsystem_register);
540EXPORT_SYMBOL(subsystem_unregister);
541EXPORT_SYMBOL(subsys_create_file);
542EXPORT_SYMBOL(subsys_remove_file);