[PATCH] s390: fix assignment instead of check in ccw_device_set_online()
[wandboard.git] / lib / kobject.c
blobefe67fa96a71647b3af9f6c010fd2abc4a661619
1 /*
2 * kobject.c - library routines for handling generic kernel objects
4 * Copyright (c) 2002-2003 Patrick Mochel <mochel@osdl.org>
6 * This file is released under the GPLv2.
9 * Please see the file Documentation/kobject.txt for critical information
10 * about using the kobject interface.
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>
19 /**
20 * populate_dir - populate directory with attributes.
21 * @kobj: object we're working on.
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.
31 static int populate_dir(struct kobject * kobj)
33 struct kobj_type * t = get_ktype(kobj);
34 struct attribute * attr;
35 int error = 0;
36 int i;
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;
44 return error;
47 static int create_dir(struct kobject * kobj)
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);
57 return error;
60 static inline struct kobject * to_kobj(struct list_head * entry)
62 return container_of(entry,struct kobject,entry);
65 static int get_kobj_path_length(struct kobject *kobj)
67 int length = 1;
68 struct kobject * parent = kobj;
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.
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;
83 static void fill_kobj_path(struct kobject *kobj, char *path, int length)
85 struct kobject * parent;
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) = '/';
96 pr_debug("%s: path = '%s'\n",__FUNCTION__,path);
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().
103 * @kobj: kobject in question, with which to build the path
104 * @gfp_mask: the allocation type used to allocate the path
106 char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
108 char *path;
109 int len;
111 len = get_kobj_path_length(kobj);
112 if (len == 0)
113 return NULL;
114 path = kmalloc(len, gfp_mask);
115 if (!path)
116 return NULL;
117 memset(path, 0x00, len);
118 fill_kobj_path(kobj, path, len);
120 return path;
124 * kobject_init - initialize object.
125 * @kobj: object in question.
127 void kobject_init(struct kobject * kobj)
129 kref_init(&kobj->kref);
130 INIT_LIST_HEAD(&kobj->entry);
131 kobj->kset = kset_get(kobj->kset);
136 * unlink - remove kobject from kset list.
137 * @kobj: kobject.
139 * Remove the kobject from the kset list and decrement
140 * its parent's refcount.
141 * This is separated out, so we can use it in both
142 * kobject_del() and kobject_add() on error.
145 static void unlink(struct kobject * kobj)
147 if (kobj->kset) {
148 spin_lock(&kobj->kset->list_lock);
149 list_del_init(&kobj->entry);
150 spin_unlock(&kobj->kset->list_lock);
152 kobject_put(kobj);
156 * kobject_add - add an object to the hierarchy.
157 * @kobj: object.
160 int kobject_add(struct kobject * kobj)
162 int error = 0;
163 struct kobject * parent;
165 if (!(kobj = kobject_get(kobj)))
166 return -ENOENT;
167 if (!kobj->k_name)
168 kobj->k_name = kobj->name;
169 if (!kobj->k_name) {
170 pr_debug("kobject attempted to be registered with no name!\n");
171 WARN_ON(1);
172 return -EINVAL;
174 parent = kobject_get(kobj->parent);
176 pr_debug("kobject %s: registering. parent: %s, set: %s\n",
177 kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>",
178 kobj->kset ? kobj->kset->kobj.name : "<NULL>" );
180 if (kobj->kset) {
181 spin_lock(&kobj->kset->list_lock);
183 if (!parent)
184 parent = kobject_get(&kobj->kset->kobj);
186 list_add_tail(&kobj->entry,&kobj->kset->list);
187 spin_unlock(&kobj->kset->list_lock);
189 kobj->parent = parent;
191 error = create_dir(kobj);
192 if (error) {
193 /* unlink does the kobject_put() for us */
194 unlink(kobj);
195 if (parent)
196 kobject_put(parent);
199 return error;
204 * kobject_register - initialize and add an object.
205 * @kobj: object in question.
208 int kobject_register(struct kobject * kobj)
210 int error = 0;
211 if (kobj) {
212 kobject_init(kobj);
213 error = kobject_add(kobj);
214 if (error) {
215 printk("kobject_register failed for %s (%d)\n",
216 kobject_name(kobj),error);
217 dump_stack();
218 } else
219 kobject_uevent(kobj, KOBJ_ADD);
220 } else
221 error = -EINVAL;
222 return error;
227 * kobject_set_name - Set the name of an object
228 * @kobj: object.
229 * @fmt: format string used to build the name
231 * If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
232 * string that @kobj->k_name points to. Otherwise, use the static
233 * @kobj->name array.
235 int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
237 int error = 0;
238 int limit = KOBJ_NAME_LEN;
239 int need;
240 va_list args;
241 char * name;
244 * First, try the static array
246 va_start(args,fmt);
247 need = vsnprintf(kobj->name,limit,fmt,args);
248 va_end(args);
249 if (need < limit)
250 name = kobj->name;
251 else {
253 * Need more space? Allocate it and try again
255 limit = need + 1;
256 name = kmalloc(limit,GFP_KERNEL);
257 if (!name) {
258 error = -ENOMEM;
259 goto Done;
261 va_start(args,fmt);
262 need = vsnprintf(name,limit,fmt,args);
263 va_end(args);
265 /* Still? Give up. */
266 if (need >= limit) {
267 kfree(name);
268 error = -EFAULT;
269 goto Done;
273 /* Free the old name, if necessary. */
274 if (kobj->k_name && kobj->k_name != kobj->name)
275 kfree(kobj->k_name);
277 /* Now, set the new name */
278 kobj->k_name = name;
279 Done:
280 return error;
283 EXPORT_SYMBOL(kobject_set_name);
287 * kobject_rename - change the name of an object
288 * @kobj: object in question.
289 * @new_name: object's new name
292 int kobject_rename(struct kobject * kobj, const char *new_name)
294 int error = 0;
296 kobj = kobject_get(kobj);
297 if (!kobj)
298 return -EINVAL;
299 error = sysfs_rename_dir(kobj, new_name);
300 kobject_put(kobj);
302 return error;
306 * kobject_del - unlink kobject from hierarchy.
307 * @kobj: object.
310 void kobject_del(struct kobject * kobj)
312 sysfs_remove_dir(kobj);
313 unlink(kobj);
317 * kobject_unregister - remove object from hierarchy and decrement refcount.
318 * @kobj: object going away.
321 void kobject_unregister(struct kobject * kobj)
323 pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
324 kobject_uevent(kobj, KOBJ_REMOVE);
325 kobject_del(kobj);
326 kobject_put(kobj);
330 * kobject_get - increment refcount for object.
331 * @kobj: object.
334 struct kobject * kobject_get(struct kobject * kobj)
336 if (kobj)
337 kref_get(&kobj->kref);
338 return kobj;
342 * kobject_cleanup - free kobject resources.
343 * @kobj: object.
346 void kobject_cleanup(struct kobject * kobj)
348 struct kobj_type * t = get_ktype(kobj);
349 struct kset * s = kobj->kset;
350 struct kobject * parent = kobj->parent;
352 pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
353 if (kobj->k_name != kobj->name)
354 kfree(kobj->k_name);
355 kobj->k_name = NULL;
356 if (t && t->release)
357 t->release(kobj);
358 if (s)
359 kset_put(s);
360 if (parent)
361 kobject_put(parent);
364 static void kobject_release(struct kref *kref)
366 kobject_cleanup(container_of(kref, struct kobject, kref));
370 * kobject_put - decrement refcount for object.
371 * @kobj: object.
373 * Decrement the refcount, and if 0, call kobject_cleanup().
375 void kobject_put(struct kobject * kobj)
377 if (kobj)
378 kref_put(&kobj->kref, kobject_release);
383 * kset_init - initialize a kset for use
384 * @k: kset
387 void kset_init(struct kset * k)
389 kobject_init(&k->kobj);
390 INIT_LIST_HEAD(&k->list);
391 spin_lock_init(&k->list_lock);
396 * kset_add - add a kset object to the hierarchy.
397 * @k: kset.
399 * Simply, this adds the kset's embedded kobject to the
400 * hierarchy.
401 * We also try to make sure that the kset's embedded kobject
402 * has a parent before it is added. We only care if the embedded
403 * kobject is not part of a kset itself, since kobject_add()
404 * assigns a parent in that case.
405 * If that is the case, and the kset has a controlling subsystem,
406 * then we set the kset's parent to be said subsystem.
409 int kset_add(struct kset * k)
411 if (!k->kobj.parent && !k->kobj.kset && k->subsys)
412 k->kobj.parent = &k->subsys->kset.kobj;
414 return kobject_add(&k->kobj);
419 * kset_register - initialize and add a kset.
420 * @k: kset.
423 int kset_register(struct kset * k)
425 kset_init(k);
426 return kset_add(k);
431 * kset_unregister - remove a kset.
432 * @k: kset.
435 void kset_unregister(struct kset * k)
437 kobject_unregister(&k->kobj);
442 * kset_find_obj - search for object in kset.
443 * @kset: kset we're looking in.
444 * @name: object's name.
446 * Lock kset via @kset->subsys, and iterate over @kset->list,
447 * looking for a matching kobject. If matching object is found
448 * take a reference and return the object.
451 struct kobject * kset_find_obj(struct kset * kset, const char * name)
453 struct list_head * entry;
454 struct kobject * ret = NULL;
456 spin_lock(&kset->list_lock);
457 list_for_each(entry,&kset->list) {
458 struct kobject * k = to_kobj(entry);
459 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
460 ret = kobject_get(k);
461 break;
464 spin_unlock(&kset->list_lock);
465 return ret;
469 void subsystem_init(struct subsystem * s)
471 init_rwsem(&s->rwsem);
472 kset_init(&s->kset);
476 * subsystem_register - register a subsystem.
477 * @s: the subsystem we're registering.
479 * Once we register the subsystem, we want to make sure that
480 * the kset points back to this subsystem for correct usage of
481 * the rwsem.
484 int subsystem_register(struct subsystem * s)
486 int error;
488 subsystem_init(s);
489 pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
491 if (!(error = kset_add(&s->kset))) {
492 if (!s->kset.subsys)
493 s->kset.subsys = s;
495 return error;
498 void subsystem_unregister(struct subsystem * s)
500 pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
501 kset_unregister(&s->kset);
506 * subsystem_create_file - export sysfs attribute file.
507 * @s: subsystem.
508 * @a: subsystem attribute descriptor.
511 int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
513 int error = 0;
514 if (subsys_get(s)) {
515 error = sysfs_create_file(&s->kset.kobj,&a->attr);
516 subsys_put(s);
518 return error;
523 * subsystem_remove_file - remove sysfs attribute file.
524 * @s: subsystem.
525 * @a: attribute desciptor.
528 void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
530 if (subsys_get(s)) {
531 sysfs_remove_file(&s->kset.kobj,&a->attr);
532 subsys_put(s);
536 EXPORT_SYMBOL(kobject_init);
537 EXPORT_SYMBOL(kobject_register);
538 EXPORT_SYMBOL(kobject_unregister);
539 EXPORT_SYMBOL(kobject_get);
540 EXPORT_SYMBOL(kobject_put);
541 EXPORT_SYMBOL(kobject_add);
542 EXPORT_SYMBOL(kobject_del);
544 EXPORT_SYMBOL(kset_register);
545 EXPORT_SYMBOL(kset_unregister);
546 EXPORT_SYMBOL(kset_find_obj);
548 EXPORT_SYMBOL(subsystem_init);
549 EXPORT_SYMBOL(subsystem_register);
550 EXPORT_SYMBOL(subsystem_unregister);
551 EXPORT_SYMBOL(subsys_create_file);
552 EXPORT_SYMBOL(subsys_remove_file);