projects/linux·blob v2.6.20 · 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#include <linux/slab.h>
18
19/**
20 * populate_dir - populate directory with attributes.
21 * @kobj: object we're working on.
22 *
23 * Most subsystems have a set of default attributes that
24 * are associated with an object that registers with them.
25 * This is a helper called during object registration that
26 * loops through the default attributes of the subsystem
27 * and creates attributes files for them in sysfs.
28 *
29 */
30
31static int populate_dir(struct kobject * kobj)
32{
33 struct kobj_type * t = get_ktype(kobj);
34 struct attribute * attr;
35 int error = 0;
36 int i;
37
38 if (t && t->default_attrs) {
39 for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
40 if ((error = sysfs_create_file(kobj,attr)))
41 break;
42 }
43 }
44 return error;
45}
46
47static int create_dir(struct kobject * kobj)
48{
49 int error = 0;
50 if (kobject_name(kobj)) {
51 error = sysfs_create_dir(kobj);
52 if (!error) {
53 if ((error = populate_dir(kobj)))
54 sysfs_remove_dir(kobj);
55 }
56 }
57 return error;
58}
59
60static inline struct kobject * to_kobj(struct list_head * entry)
61{
62 return container_of(entry,struct kobject,entry);
63}
64
65static int get_kobj_path_length(struct kobject *kobj)
66{
67 int length = 1;
68 struct kobject * parent = kobj;
69
70 /* walk up the ancestors until we hit the one pointing to the
71 * root.
72 * Add 1 to strlen for leading '/' of each level.
73 */
74 do {
75 if (kobject_name(parent) == NULL)
76 return 0;
77 length += strlen(kobject_name(parent)) + 1;
78 parent = parent->parent;
79 } while (parent);
80 return length;
81}
82
83static void fill_kobj_path(struct kobject *kobj, char *path, int length)
84{
85 struct kobject * parent;
86
87 --length;
88 for (parent = kobj; parent; parent = parent->parent) {
89 int cur = strlen(kobject_name(parent));
90 /* back up enough to print this name with '/' */
91 length -= cur;
92 strncpy (path + length, kobject_name(parent), cur);
93 *(path + --length) = '/';
94 }
95
96 pr_debug("%s: path = '%s'\n",__FUNCTION__,path);
97}
98
99/**
100 * kobject_get_path - generate and return the path associated with a given kobj
101 * and kset pair. The result must be freed by the caller with kfree().
102 *
103 * @kobj: kobject in question, with which to build the path
104 * @gfp_mask: the allocation type used to allocate the path
105 */
106char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
107{
108 char *path;
109 int len;
110
111 len = get_kobj_path_length(kobj);
112 if (len == 0)
113 return NULL;
114 path = kzalloc(len, gfp_mask);
115 if (!path)
116 return NULL;
117 fill_kobj_path(kobj, path, len);
118
119 return path;
120}
121EXPORT_SYMBOL_GPL(kobject_get_path);
122
123/**
124 * kobject_init - initialize object.
125 * @kobj: object in question.
126 */
127void kobject_init(struct kobject * kobj)
128{
129 kref_init(&kobj->kref);
130 INIT_LIST_HEAD(&kobj->entry);
131 init_waitqueue_head(&kobj->poll);
132 kobj->kset = kset_get(kobj->kset);
133}
134
135
136/**
137 * unlink - remove kobject from kset list.
138 * @kobj: kobject.
139 *
140 * Remove the kobject from the kset list and decrement
141 * its parent's refcount.
142 * This is separated out, so we can use it in both
143 * kobject_del() and kobject_add() on error.
144 */
145
146static void unlink(struct kobject * kobj)
147{
148 if (kobj->kset) {
149 spin_lock(&kobj->kset->list_lock);
150 list_del_init(&kobj->entry);
151 spin_unlock(&kobj->kset->list_lock);
152 }
153 kobject_put(kobj);
154}
155
156/**
157 * kobject_add - add an object to the hierarchy.
158 * @kobj: object.
159 */
160
161int kobject_add(struct kobject * kobj)
162{
163 int error = 0;
164 struct kobject * parent;
165
166 if (!(kobj = kobject_get(kobj)))
167 return -ENOENT;
168 if (!kobj->k_name)
169 kobj->k_name = kobj->name;
170 if (!kobj->k_name) {
171 pr_debug("kobject attempted to be registered with no name!\n");
172 WARN_ON(1);
173 return -EINVAL;
174 }
175 parent = kobject_get(kobj->parent);
176
177 pr_debug("kobject %s: registering. parent: %s, set: %s\n",
178 kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>",
179 kobj->kset ? kobj->kset->kobj.name : "<NULL>" );
180
181 if (kobj->kset) {
182 spin_lock(&kobj->kset->list_lock);
183
184 if (!parent)
185 parent = kobject_get(&kobj->kset->kobj);
186
187 list_add_tail(&kobj->entry,&kobj->kset->list);
188 spin_unlock(&kobj->kset->list_lock);
189 }
190 kobj->parent = parent;
191
192 error = create_dir(kobj);
193 if (error) {
194 /* unlink does the kobject_put() for us */
195 unlink(kobj);
196 if (parent)
197 kobject_put(parent);
198
199 /* be noisy on error issues */
200 if (error == -EEXIST)
201 printk("kobject_add failed for %s with -EEXIST, "
202 "don't try to register things with the "
203 "same name in the same directory.\n",
204 kobject_name(kobj));
205 else
206 printk("kobject_add failed for %s (%d)\n",
207 kobject_name(kobj), error);
208 dump_stack();
209 }
210
211 return error;
212}
213
214
215/**
216 * kobject_register - initialize and add an object.
217 * @kobj: object in question.
218 */
219
220int kobject_register(struct kobject * kobj)
221{
222 int error = -EINVAL;
223 if (kobj) {
224 kobject_init(kobj);
225 error = kobject_add(kobj);
226 if (!error)
227 kobject_uevent(kobj, KOBJ_ADD);
228 }
229 return error;
230}
231
232
233/**
234 * kobject_set_name - Set the name of an object
235 * @kobj: object.
236 * @fmt: format string used to build the name
237 *
238 * If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
239 * string that @kobj->k_name points to. Otherwise, use the static
240 * @kobj->name array.
241 */
242int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
243{
244 int error = 0;
245 int limit = KOBJ_NAME_LEN;
246 int need;
247 va_list args;
248 char * name;
249
250 /*
251 * First, try the static array
252 */
253 va_start(args,fmt);
254 need = vsnprintf(kobj->name,limit,fmt,args);
255 va_end(args);
256 if (need < limit)
257 name = kobj->name;
258 else {
259 /*
260 * Need more space? Allocate it and try again
261 */
262 limit = need + 1;
263 name = kmalloc(limit,GFP_KERNEL);
264 if (!name) {
265 error = -ENOMEM;
266 goto Done;
267 }
268 va_start(args,fmt);
269 need = vsnprintf(name,limit,fmt,args);
270 va_end(args);
271
272 /* Still? Give up. */
273 if (need >= limit) {
274 kfree(name);
275 error = -EFAULT;
276 goto Done;
277 }
278 }
279
280 /* Free the old name, if necessary. */
281 if (kobj->k_name && kobj->k_name != kobj->name)
282 kfree(kobj->k_name);
283
284 /* Now, set the new name */
285 kobj->k_name = name;
286 Done:
287 return error;
288}
289
290EXPORT_SYMBOL(kobject_set_name);
291
292
293/**
294 * kobject_rename - change the name of an object
295 * @kobj: object in question.
296 * @new_name: object's new name
297 */
298
299int kobject_rename(struct kobject * kobj, const char *new_name)
300{
301 int error = 0;
302
303 kobj = kobject_get(kobj);
304 if (!kobj)
305 return -EINVAL;
306 error = sysfs_rename_dir(kobj, new_name);
307 kobject_put(kobj);
308
309 return error;
310}
311
312/**
313 * kobject_move - move object to another parent
314 * @kobj: object in question.
315 * @new_parent: object's new parent
316 */
317
318int kobject_move(struct kobject *kobj, struct kobject *new_parent)
319{
320 int error;
321 struct kobject *old_parent;
322 const char *devpath = NULL;
323 char *devpath_string = NULL;
324 char *envp[2];
325
326 kobj = kobject_get(kobj);
327 if (!kobj)
328 return -EINVAL;
329 new_parent = kobject_get(new_parent);
330 if (!new_parent) {
331 error = -EINVAL;
332 goto out;
333 }
334 /* old object path */
335 devpath = kobject_get_path(kobj, GFP_KERNEL);
336 if (!devpath) {
337 error = -ENOMEM;
338 goto out;
339 }
340 devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
341 if (!devpath_string) {
342 error = -ENOMEM;
343 goto out;
344 }
345 sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
346 envp[0] = devpath_string;
347 envp[1] = NULL;
348 error = sysfs_move_dir(kobj, new_parent);
349 if (error)
350 goto out;
351 old_parent = kobj->parent;
352 kobj->parent = new_parent;
353 kobject_put(old_parent);
354 kobject_uevent_env(kobj, KOBJ_MOVE, envp);
355out:
356 kobject_put(kobj);
357 kfree(devpath_string);
358 kfree(devpath);
359 return error;
360}
361
362/**
363 * kobject_del - unlink kobject from hierarchy.
364 * @kobj: object.
365 */
366
367void kobject_del(struct kobject * kobj)
368{
369 sysfs_remove_dir(kobj);
370 unlink(kobj);
371}
372
373/**
374 * kobject_unregister - remove object from hierarchy and decrement refcount.
375 * @kobj: object going away.
376 */
377
378void kobject_unregister(struct kobject * kobj)
379{
380 pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
381 kobject_uevent(kobj, KOBJ_REMOVE);
382 kobject_del(kobj);
383 kobject_put(kobj);
384}
385
386/**
387 * kobject_get - increment refcount for object.
388 * @kobj: object.
389 */
390
391struct kobject * kobject_get(struct kobject * kobj)
392{
393 if (kobj)
394 kref_get(&kobj->kref);
395 return kobj;
396}
397
398/**
399 * kobject_cleanup - free kobject resources.
400 * @kobj: object.
401 */
402
403void kobject_cleanup(struct kobject * kobj)
404{
405 struct kobj_type * t = get_ktype(kobj);
406 struct kset * s = kobj->kset;
407 struct kobject * parent = kobj->parent;
408
409 pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
410 if (kobj->k_name != kobj->name)
411 kfree(kobj->k_name);
412 kobj->k_name = NULL;
413 if (t && t->release)
414 t->release(kobj);
415 if (s)
416 kset_put(s);
417 if (parent)
418 kobject_put(parent);
419}
420
421static void kobject_release(struct kref *kref)
422{
423 kobject_cleanup(container_of(kref, struct kobject, kref));
424}
425
426/**
427 * kobject_put - decrement refcount for object.
428 * @kobj: object.
429 *
430 * Decrement the refcount, and if 0, call kobject_cleanup().
431 */
432void kobject_put(struct kobject * kobj)
433{
434 if (kobj)
435 kref_put(&kobj->kref, kobject_release);
436}
437
438
439static void dir_release(struct kobject *kobj)
440{
441 kfree(kobj);
442}
443
444static struct kobj_type dir_ktype = {
445 .release = dir_release,
446 .sysfs_ops = NULL,
447 .default_attrs = NULL,
448};
449
450/**
451 * kobject_add_dir - add sub directory of object.
452 * @parent: object in which a directory is created.
453 * @name: directory name.
454 *
455 * Add a plain directory object as child of given object.
456 */
457struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
458{
459 struct kobject *k;
460 int ret;
461
462 if (!parent)
463 return NULL;
464
465 k = kzalloc(sizeof(*k), GFP_KERNEL);
466 if (!k)
467 return NULL;
468
469 k->parent = parent;
470 k->ktype = &dir_ktype;
471 kobject_set_name(k, name);
472 ret = kobject_register(k);
473 if (ret < 0) {
474 printk(KERN_WARNING "kobject_add_dir: "
475 "kobject_register error: %d\n", ret);
476 kobject_del(k);
477 return NULL;
478 }
479
480 return k;
481}
482
483/**
484 * kset_init - initialize a kset for use
485 * @k: kset
486 */
487
488void kset_init(struct kset * k)
489{
490 kobject_init(&k->kobj);
491 INIT_LIST_HEAD(&k->list);
492 spin_lock_init(&k->list_lock);
493}
494
495
496/**
497 * kset_add - add a kset object to the hierarchy.
498 * @k: kset.
499 *
500 * Simply, this adds the kset's embedded kobject to the
501 * hierarchy.
502 * We also try to make sure that the kset's embedded kobject
503 * has a parent before it is added. We only care if the embedded
504 * kobject is not part of a kset itself, since kobject_add()
505 * assigns a parent in that case.
506 * If that is the case, and the kset has a controlling subsystem,
507 * then we set the kset's parent to be said subsystem.
508 */
509
510int kset_add(struct kset * k)
511{
512 if (!k->kobj.parent && !k->kobj.kset && k->subsys)
513 k->kobj.parent = &k->subsys->kset.kobj;
514
515 return kobject_add(&k->kobj);
516}
517
518
519/**
520 * kset_register - initialize and add a kset.
521 * @k: kset.
522 */
523
524int kset_register(struct kset * k)
525{
526 kset_init(k);
527 return kset_add(k);
528}
529
530
531/**
532 * kset_unregister - remove a kset.
533 * @k: kset.
534 */
535
536void kset_unregister(struct kset * k)
537{
538 kobject_unregister(&k->kobj);
539}
540
541
542/**
543 * kset_find_obj - search for object in kset.
544 * @kset: kset we're looking in.
545 * @name: object's name.
546 *
547 * Lock kset via @kset->subsys, and iterate over @kset->list,
548 * looking for a matching kobject. If matching object is found
549 * take a reference and return the object.
550 */
551
552struct kobject * kset_find_obj(struct kset * kset, const char * name)
553{
554 struct list_head * entry;
555 struct kobject * ret = NULL;
556
557 spin_lock(&kset->list_lock);
558 list_for_each(entry,&kset->list) {
559 struct kobject * k = to_kobj(entry);
560 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
561 ret = kobject_get(k);
562 break;
563 }
564 }
565 spin_unlock(&kset->list_lock);
566 return ret;
567}
568
569
570void subsystem_init(struct subsystem * s)
571{
572 init_rwsem(&s->rwsem);
573 kset_init(&s->kset);
574}
575
576/**
577 * subsystem_register - register a subsystem.
578 * @s: the subsystem we're registering.
579 *
580 * Once we register the subsystem, we want to make sure that
581 * the kset points back to this subsystem for correct usage of
582 * the rwsem.
583 */
584
585int subsystem_register(struct subsystem * s)
586{
587 int error;
588
589 subsystem_init(s);
590 pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
591
592 if (!(error = kset_add(&s->kset))) {
593 if (!s->kset.subsys)
594 s->kset.subsys = s;
595 }
596 return error;
597}
598
599void subsystem_unregister(struct subsystem * s)
600{
601 pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
602 kset_unregister(&s->kset);
603}
604
605
606/**
607 * subsystem_create_file - export sysfs attribute file.
608 * @s: subsystem.
609 * @a: subsystem attribute descriptor.
610 */
611
612int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
613{
614 int error = 0;
615 if (subsys_get(s)) {
616 error = sysfs_create_file(&s->kset.kobj,&a->attr);
617 subsys_put(s);
618 }
619 return error;
620}
621
622
623/**
624 * subsystem_remove_file - remove sysfs attribute file.
625 * @s: subsystem.
626 * @a: attribute desciptor.
627 */
628#if 0
629void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
630{
631 if (subsys_get(s)) {
632 sysfs_remove_file(&s->kset.kobj,&a->attr);
633 subsys_put(s);
634 }
635}
636#endif /* 0 */
637
638EXPORT_SYMBOL(kobject_init);
639EXPORT_SYMBOL(kobject_register);
640EXPORT_SYMBOL(kobject_unregister);
641EXPORT_SYMBOL(kobject_get);
642EXPORT_SYMBOL(kobject_put);
643EXPORT_SYMBOL(kobject_add);
644EXPORT_SYMBOL(kobject_del);
645
646EXPORT_SYMBOL(kset_register);
647EXPORT_SYMBOL(kset_unregister);
648
649EXPORT_SYMBOL(subsystem_register);
650EXPORT_SYMBOL(subsystem_unregister);
651EXPORT_SYMBOL(subsys_create_file);