xref: /openbmc/linux/lib/kobject.c (revision 82e6fdd6)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * kobject.c - library routines for handling generic kernel objects
4  *
5  * Copyright (c) 2002-2003 Patrick Mochel <mochel@osdl.org>
6  * Copyright (c) 2006-2007 Greg Kroah-Hartman <greg@kroah.com>
7  * Copyright (c) 2006-2007 Novell Inc.
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/export.h>
16 #include <linux/stat.h>
17 #include <linux/slab.h>
18 #include <linux/random.h>
19 
20 /**
21  * kobject_namespace - return @kobj's namespace tag
22  * @kobj: kobject in question
23  *
24  * Returns namespace tag of @kobj if its parent has namespace ops enabled
25  * and thus @kobj should have a namespace tag associated with it.  Returns
26  * %NULL otherwise.
27  */
28 const void *kobject_namespace(struct kobject *kobj)
29 {
30 	const struct kobj_ns_type_operations *ns_ops = kobj_ns_ops(kobj);
31 
32 	if (!ns_ops || ns_ops->type == KOBJ_NS_TYPE_NONE)
33 		return NULL;
34 
35 	return kobj->ktype->namespace(kobj);
36 }
37 
38 /*
39  * populate_dir - populate directory with attributes.
40  * @kobj: object we're working on.
41  *
42  * Most subsystems have a set of default attributes that are associated
43  * with an object that registers with them.  This is a helper called during
44  * object registration that loops through the default attributes of the
45  * subsystem and creates attributes files for them in sysfs.
46  */
47 static int populate_dir(struct kobject *kobj)
48 {
49 	struct kobj_type *t = get_ktype(kobj);
50 	struct attribute *attr;
51 	int error = 0;
52 	int i;
53 
54 	if (t && t->default_attrs) {
55 		for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
56 			error = sysfs_create_file(kobj, attr);
57 			if (error)
58 				break;
59 		}
60 	}
61 	return error;
62 }
63 
64 static int create_dir(struct kobject *kobj)
65 {
66 	const struct kobj_ns_type_operations *ops;
67 	int error;
68 
69 	error = sysfs_create_dir_ns(kobj, kobject_namespace(kobj));
70 	if (error)
71 		return error;
72 
73 	error = populate_dir(kobj);
74 	if (error) {
75 		sysfs_remove_dir(kobj);
76 		return error;
77 	}
78 
79 	/*
80 	 * @kobj->sd may be deleted by an ancestor going away.  Hold an
81 	 * extra reference so that it stays until @kobj is gone.
82 	 */
83 	sysfs_get(kobj->sd);
84 
85 	/*
86 	 * If @kobj has ns_ops, its children need to be filtered based on
87 	 * their namespace tags.  Enable namespace support on @kobj->sd.
88 	 */
89 	ops = kobj_child_ns_ops(kobj);
90 	if (ops) {
91 		BUG_ON(ops->type <= KOBJ_NS_TYPE_NONE);
92 		BUG_ON(ops->type >= KOBJ_NS_TYPES);
93 		BUG_ON(!kobj_ns_type_registered(ops->type));
94 
95 		sysfs_enable_ns(kobj->sd);
96 	}
97 
98 	return 0;
99 }
100 
101 static int get_kobj_path_length(struct kobject *kobj)
102 {
103 	int length = 1;
104 	struct kobject *parent = kobj;
105 
106 	/* walk up the ancestors until we hit the one pointing to the
107 	 * root.
108 	 * Add 1 to strlen for leading '/' of each level.
109 	 */
110 	do {
111 		if (kobject_name(parent) == NULL)
112 			return 0;
113 		length += strlen(kobject_name(parent)) + 1;
114 		parent = parent->parent;
115 	} while (parent);
116 	return length;
117 }
118 
119 static void fill_kobj_path(struct kobject *kobj, char *path, int length)
120 {
121 	struct kobject *parent;
122 
123 	--length;
124 	for (parent = kobj; parent; parent = parent->parent) {
125 		int cur = strlen(kobject_name(parent));
126 		/* back up enough to print this name with '/' */
127 		length -= cur;
128 		strncpy(path + length, kobject_name(parent), cur);
129 		*(path + --length) = '/';
130 	}
131 
132 	pr_debug("kobject: '%s' (%p): %s: path = '%s'\n", kobject_name(kobj),
133 		 kobj, __func__, path);
134 }
135 
136 /**
137  * kobject_get_path - generate and return the path associated with a given kobj and kset pair.
138  *
139  * @kobj:	kobject in question, with which to build the path
140  * @gfp_mask:	the allocation type used to allocate the path
141  *
142  * The result must be freed by the caller with kfree().
143  */
144 char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
145 {
146 	char *path;
147 	int len;
148 
149 	len = get_kobj_path_length(kobj);
150 	if (len == 0)
151 		return NULL;
152 	path = kzalloc(len, gfp_mask);
153 	if (!path)
154 		return NULL;
155 	fill_kobj_path(kobj, path, len);
156 
157 	return path;
158 }
159 EXPORT_SYMBOL_GPL(kobject_get_path);
160 
161 /* add the kobject to its kset's list */
162 static void kobj_kset_join(struct kobject *kobj)
163 {
164 	if (!kobj->kset)
165 		return;
166 
167 	kset_get(kobj->kset);
168 	spin_lock(&kobj->kset->list_lock);
169 	list_add_tail(&kobj->entry, &kobj->kset->list);
170 	spin_unlock(&kobj->kset->list_lock);
171 }
172 
173 /* remove the kobject from its kset's list */
174 static void kobj_kset_leave(struct kobject *kobj)
175 {
176 	if (!kobj->kset)
177 		return;
178 
179 	spin_lock(&kobj->kset->list_lock);
180 	list_del_init(&kobj->entry);
181 	spin_unlock(&kobj->kset->list_lock);
182 	kset_put(kobj->kset);
183 }
184 
185 static void kobject_init_internal(struct kobject *kobj)
186 {
187 	if (!kobj)
188 		return;
189 	kref_init(&kobj->kref);
190 	INIT_LIST_HEAD(&kobj->entry);
191 	kobj->state_in_sysfs = 0;
192 	kobj->state_add_uevent_sent = 0;
193 	kobj->state_remove_uevent_sent = 0;
194 	kobj->state_initialized = 1;
195 }
196 
197 
198 static int kobject_add_internal(struct kobject *kobj)
199 {
200 	int error = 0;
201 	struct kobject *parent;
202 
203 	if (!kobj)
204 		return -ENOENT;
205 
206 	if (!kobj->name || !kobj->name[0]) {
207 		WARN(1, "kobject: (%p): attempted to be registered with empty "
208 			 "name!\n", kobj);
209 		return -EINVAL;
210 	}
211 
212 	parent = kobject_get(kobj->parent);
213 
214 	/* join kset if set, use it as parent if we do not already have one */
215 	if (kobj->kset) {
216 		if (!parent)
217 			parent = kobject_get(&kobj->kset->kobj);
218 		kobj_kset_join(kobj);
219 		kobj->parent = parent;
220 	}
221 
222 	pr_debug("kobject: '%s' (%p): %s: parent: '%s', set: '%s'\n",
223 		 kobject_name(kobj), kobj, __func__,
224 		 parent ? kobject_name(parent) : "<NULL>",
225 		 kobj->kset ? kobject_name(&kobj->kset->kobj) : "<NULL>");
226 
227 	error = create_dir(kobj);
228 	if (error) {
229 		kobj_kset_leave(kobj);
230 		kobject_put(parent);
231 		kobj->parent = NULL;
232 
233 		/* be noisy on error issues */
234 		if (error == -EEXIST)
235 			WARN(1, "%s failed for %s with "
236 			     "-EEXIST, don't try to register things with "
237 			     "the same name in the same directory.\n",
238 			     __func__, kobject_name(kobj));
239 		else
240 			WARN(1, "%s failed for %s (error: %d parent: %s)\n",
241 			     __func__, kobject_name(kobj), error,
242 			     parent ? kobject_name(parent) : "'none'");
243 	} else
244 		kobj->state_in_sysfs = 1;
245 
246 	return error;
247 }
248 
249 /**
250  * kobject_set_name_vargs - Set the name of an kobject
251  * @kobj: struct kobject to set the name of
252  * @fmt: format string used to build the name
253  * @vargs: vargs to format the string.
254  */
255 int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
256 				  va_list vargs)
257 {
258 	const char *s;
259 
260 	if (kobj->name && !fmt)
261 		return 0;
262 
263 	s = kvasprintf_const(GFP_KERNEL, fmt, vargs);
264 	if (!s)
265 		return -ENOMEM;
266 
267 	/*
268 	 * ewww... some of these buggers have '/' in the name ... If
269 	 * that's the case, we need to make sure we have an actual
270 	 * allocated copy to modify, since kvasprintf_const may have
271 	 * returned something from .rodata.
272 	 */
273 	if (strchr(s, '/')) {
274 		char *t;
275 
276 		t = kstrdup(s, GFP_KERNEL);
277 		kfree_const(s);
278 		if (!t)
279 			return -ENOMEM;
280 		strreplace(t, '/', '!');
281 		s = t;
282 	}
283 	kfree_const(kobj->name);
284 	kobj->name = s;
285 
286 	return 0;
287 }
288 
289 /**
290  * kobject_set_name - Set the name of a kobject
291  * @kobj: struct kobject to set the name of
292  * @fmt: format string used to build the name
293  *
294  * This sets the name of the kobject.  If you have already added the
295  * kobject to the system, you must call kobject_rename() in order to
296  * change the name of the kobject.
297  */
298 int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
299 {
300 	va_list vargs;
301 	int retval;
302 
303 	va_start(vargs, fmt);
304 	retval = kobject_set_name_vargs(kobj, fmt, vargs);
305 	va_end(vargs);
306 
307 	return retval;
308 }
309 EXPORT_SYMBOL(kobject_set_name);
310 
311 /**
312  * kobject_init - initialize a kobject structure
313  * @kobj: pointer to the kobject to initialize
314  * @ktype: pointer to the ktype for this kobject.
315  *
316  * This function will properly initialize a kobject such that it can then
317  * be passed to the kobject_add() call.
318  *
319  * After this function is called, the kobject MUST be cleaned up by a call
320  * to kobject_put(), not by a call to kfree directly to ensure that all of
321  * the memory is cleaned up properly.
322  */
323 void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
324 {
325 	char *err_str;
326 
327 	if (!kobj) {
328 		err_str = "invalid kobject pointer!";
329 		goto error;
330 	}
331 	if (!ktype) {
332 		err_str = "must have a ktype to be initialized properly!\n";
333 		goto error;
334 	}
335 	if (kobj->state_initialized) {
336 		/* do not error out as sometimes we can recover */
337 		printk(KERN_ERR "kobject (%p): tried to init an initialized "
338 		       "object, something is seriously wrong.\n", kobj);
339 		dump_stack();
340 	}
341 
342 	kobject_init_internal(kobj);
343 	kobj->ktype = ktype;
344 	return;
345 
346 error:
347 	printk(KERN_ERR "kobject (%p): %s\n", kobj, err_str);
348 	dump_stack();
349 }
350 EXPORT_SYMBOL(kobject_init);
351 
352 static __printf(3, 0) int kobject_add_varg(struct kobject *kobj,
353 					   struct kobject *parent,
354 					   const char *fmt, va_list vargs)
355 {
356 	int retval;
357 
358 	retval = kobject_set_name_vargs(kobj, fmt, vargs);
359 	if (retval) {
360 		printk(KERN_ERR "kobject: can not set name properly!\n");
361 		return retval;
362 	}
363 	kobj->parent = parent;
364 	return kobject_add_internal(kobj);
365 }
366 
367 /**
368  * kobject_add - the main kobject add function
369  * @kobj: the kobject to add
370  * @parent: pointer to the parent of the kobject.
371  * @fmt: format to name the kobject with.
372  *
373  * The kobject name is set and added to the kobject hierarchy in this
374  * function.
375  *
376  * If @parent is set, then the parent of the @kobj will be set to it.
377  * If @parent is NULL, then the parent of the @kobj will be set to the
378  * kobject associated with the kset assigned to this kobject.  If no kset
379  * is assigned to the kobject, then the kobject will be located in the
380  * root of the sysfs tree.
381  *
382  * If this function returns an error, kobject_put() must be called to
383  * properly clean up the memory associated with the object.
384  * Under no instance should the kobject that is passed to this function
385  * be directly freed with a call to kfree(), that can leak memory.
386  *
387  * Note, no "add" uevent will be created with this call, the caller should set
388  * up all of the necessary sysfs files for the object and then call
389  * kobject_uevent() with the UEVENT_ADD parameter to ensure that
390  * userspace is properly notified of this kobject's creation.
391  */
392 int kobject_add(struct kobject *kobj, struct kobject *parent,
393 		const char *fmt, ...)
394 {
395 	va_list args;
396 	int retval;
397 
398 	if (!kobj)
399 		return -EINVAL;
400 
401 	if (!kobj->state_initialized) {
402 		printk(KERN_ERR "kobject '%s' (%p): tried to add an "
403 		       "uninitialized object, something is seriously wrong.\n",
404 		       kobject_name(kobj), kobj);
405 		dump_stack();
406 		return -EINVAL;
407 	}
408 	va_start(args, fmt);
409 	retval = kobject_add_varg(kobj, parent, fmt, args);
410 	va_end(args);
411 
412 	return retval;
413 }
414 EXPORT_SYMBOL(kobject_add);
415 
416 /**
417  * kobject_init_and_add - initialize a kobject structure and add it to the kobject hierarchy
418  * @kobj: pointer to the kobject to initialize
419  * @ktype: pointer to the ktype for this kobject.
420  * @parent: pointer to the parent of this kobject.
421  * @fmt: the name of the kobject.
422  *
423  * This function combines the call to kobject_init() and
424  * kobject_add().  The same type of error handling after a call to
425  * kobject_add() and kobject lifetime rules are the same here.
426  */
427 int kobject_init_and_add(struct kobject *kobj, struct kobj_type *ktype,
428 			 struct kobject *parent, const char *fmt, ...)
429 {
430 	va_list args;
431 	int retval;
432 
433 	kobject_init(kobj, ktype);
434 
435 	va_start(args, fmt);
436 	retval = kobject_add_varg(kobj, parent, fmt, args);
437 	va_end(args);
438 
439 	return retval;
440 }
441 EXPORT_SYMBOL_GPL(kobject_init_and_add);
442 
443 /**
444  * kobject_rename - change the name of an object
445  * @kobj: object in question.
446  * @new_name: object's new name
447  *
448  * It is the responsibility of the caller to provide mutual
449  * exclusion between two different calls of kobject_rename
450  * on the same kobject and to ensure that new_name is valid and
451  * won't conflict with other kobjects.
452  */
453 int kobject_rename(struct kobject *kobj, const char *new_name)
454 {
455 	int error = 0;
456 	const char *devpath = NULL;
457 	const char *dup_name = NULL, *name;
458 	char *devpath_string = NULL;
459 	char *envp[2];
460 
461 	kobj = kobject_get(kobj);
462 	if (!kobj)
463 		return -EINVAL;
464 	if (!kobj->parent)
465 		return -EINVAL;
466 
467 	devpath = kobject_get_path(kobj, GFP_KERNEL);
468 	if (!devpath) {
469 		error = -ENOMEM;
470 		goto out;
471 	}
472 	devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
473 	if (!devpath_string) {
474 		error = -ENOMEM;
475 		goto out;
476 	}
477 	sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
478 	envp[0] = devpath_string;
479 	envp[1] = NULL;
480 
481 	name = dup_name = kstrdup_const(new_name, GFP_KERNEL);
482 	if (!name) {
483 		error = -ENOMEM;
484 		goto out;
485 	}
486 
487 	error = sysfs_rename_dir_ns(kobj, new_name, kobject_namespace(kobj));
488 	if (error)
489 		goto out;
490 
491 	/* Install the new kobject name */
492 	dup_name = kobj->name;
493 	kobj->name = name;
494 
495 	/* This function is mostly/only used for network interface.
496 	 * Some hotplug package track interfaces by their name and
497 	 * therefore want to know when the name is changed by the user. */
498 	kobject_uevent_env(kobj, KOBJ_MOVE, envp);
499 
500 out:
501 	kfree_const(dup_name);
502 	kfree(devpath_string);
503 	kfree(devpath);
504 	kobject_put(kobj);
505 
506 	return error;
507 }
508 EXPORT_SYMBOL_GPL(kobject_rename);
509 
510 /**
511  * kobject_move - move object to another parent
512  * @kobj: object in question.
513  * @new_parent: object's new parent (can be NULL)
514  */
515 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
516 {
517 	int error;
518 	struct kobject *old_parent;
519 	const char *devpath = NULL;
520 	char *devpath_string = NULL;
521 	char *envp[2];
522 
523 	kobj = kobject_get(kobj);
524 	if (!kobj)
525 		return -EINVAL;
526 	new_parent = kobject_get(new_parent);
527 	if (!new_parent) {
528 		if (kobj->kset)
529 			new_parent = kobject_get(&kobj->kset->kobj);
530 	}
531 
532 	/* old object path */
533 	devpath = kobject_get_path(kobj, GFP_KERNEL);
534 	if (!devpath) {
535 		error = -ENOMEM;
536 		goto out;
537 	}
538 	devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
539 	if (!devpath_string) {
540 		error = -ENOMEM;
541 		goto out;
542 	}
543 	sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
544 	envp[0] = devpath_string;
545 	envp[1] = NULL;
546 	error = sysfs_move_dir_ns(kobj, new_parent, kobject_namespace(kobj));
547 	if (error)
548 		goto out;
549 	old_parent = kobj->parent;
550 	kobj->parent = new_parent;
551 	new_parent = NULL;
552 	kobject_put(old_parent);
553 	kobject_uevent_env(kobj, KOBJ_MOVE, envp);
554 out:
555 	kobject_put(new_parent);
556 	kobject_put(kobj);
557 	kfree(devpath_string);
558 	kfree(devpath);
559 	return error;
560 }
561 EXPORT_SYMBOL_GPL(kobject_move);
562 
563 /**
564  * kobject_del - unlink kobject from hierarchy.
565  * @kobj: object.
566  */
567 void kobject_del(struct kobject *kobj)
568 {
569 	struct kernfs_node *sd;
570 
571 	if (!kobj)
572 		return;
573 
574 	sd = kobj->sd;
575 	sysfs_remove_dir(kobj);
576 	sysfs_put(sd);
577 
578 	kobj->state_in_sysfs = 0;
579 	kobj_kset_leave(kobj);
580 	kobject_put(kobj->parent);
581 	kobj->parent = NULL;
582 }
583 EXPORT_SYMBOL(kobject_del);
584 
585 /**
586  * kobject_get - increment refcount for object.
587  * @kobj: object.
588  */
589 struct kobject *kobject_get(struct kobject *kobj)
590 {
591 	if (kobj) {
592 		if (!kobj->state_initialized)
593 			WARN(1, KERN_WARNING "kobject: '%s' (%p): is not "
594 			       "initialized, yet kobject_get() is being "
595 			       "called.\n", kobject_name(kobj), kobj);
596 		kref_get(&kobj->kref);
597 	}
598 	return kobj;
599 }
600 EXPORT_SYMBOL(kobject_get);
601 
602 struct kobject * __must_check kobject_get_unless_zero(struct kobject *kobj)
603 {
604 	if (!kobj)
605 		return NULL;
606 	if (!kref_get_unless_zero(&kobj->kref))
607 		kobj = NULL;
608 	return kobj;
609 }
610 EXPORT_SYMBOL(kobject_get_unless_zero);
611 
612 /*
613  * kobject_cleanup - free kobject resources.
614  * @kobj: object to cleanup
615  */
616 static void kobject_cleanup(struct kobject *kobj)
617 {
618 	struct kobj_type *t = get_ktype(kobj);
619 	const char *name = kobj->name;
620 
621 	pr_debug("kobject: '%s' (%p): %s, parent %p\n",
622 		 kobject_name(kobj), kobj, __func__, kobj->parent);
623 
624 	if (t && !t->release)
625 		pr_debug("kobject: '%s' (%p): does not have a release() "
626 			 "function, it is broken and must be fixed.\n",
627 			 kobject_name(kobj), kobj);
628 
629 	/* send "remove" if the caller did not do it but sent "add" */
630 	if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
631 		pr_debug("kobject: '%s' (%p): auto cleanup 'remove' event\n",
632 			 kobject_name(kobj), kobj);
633 		kobject_uevent(kobj, KOBJ_REMOVE);
634 	}
635 
636 	/* remove from sysfs if the caller did not do it */
637 	if (kobj->state_in_sysfs) {
638 		pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n",
639 			 kobject_name(kobj), kobj);
640 		kobject_del(kobj);
641 	}
642 
643 	if (t && t->release) {
644 		pr_debug("kobject: '%s' (%p): calling ktype release\n",
645 			 kobject_name(kobj), kobj);
646 		t->release(kobj);
647 	}
648 
649 	/* free name if we allocated it */
650 	if (name) {
651 		pr_debug("kobject: '%s': free name\n", name);
652 		kfree_const(name);
653 	}
654 }
655 
656 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
657 static void kobject_delayed_cleanup(struct work_struct *work)
658 {
659 	kobject_cleanup(container_of(to_delayed_work(work),
660 				     struct kobject, release));
661 }
662 #endif
663 
664 static void kobject_release(struct kref *kref)
665 {
666 	struct kobject *kobj = container_of(kref, struct kobject, kref);
667 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
668 	unsigned long delay = HZ + HZ * (get_random_int() & 0x3);
669 	pr_info("kobject: '%s' (%p): %s, parent %p (delayed %ld)\n",
670 		 kobject_name(kobj), kobj, __func__, kobj->parent, delay);
671 	INIT_DELAYED_WORK(&kobj->release, kobject_delayed_cleanup);
672 
673 	schedule_delayed_work(&kobj->release, delay);
674 #else
675 	kobject_cleanup(kobj);
676 #endif
677 }
678 
679 /**
680  * kobject_put - decrement refcount for object.
681  * @kobj: object.
682  *
683  * Decrement the refcount, and if 0, call kobject_cleanup().
684  */
685 void kobject_put(struct kobject *kobj)
686 {
687 	if (kobj) {
688 		if (!kobj->state_initialized)
689 			WARN(1, KERN_WARNING "kobject: '%s' (%p): is not "
690 			       "initialized, yet kobject_put() is being "
691 			       "called.\n", kobject_name(kobj), kobj);
692 		kref_put(&kobj->kref, kobject_release);
693 	}
694 }
695 EXPORT_SYMBOL(kobject_put);
696 
697 static void dynamic_kobj_release(struct kobject *kobj)
698 {
699 	pr_debug("kobject: (%p): %s\n", kobj, __func__);
700 	kfree(kobj);
701 }
702 
703 static struct kobj_type dynamic_kobj_ktype = {
704 	.release	= dynamic_kobj_release,
705 	.sysfs_ops	= &kobj_sysfs_ops,
706 };
707 
708 /**
709  * kobject_create - create a struct kobject dynamically
710  *
711  * This function creates a kobject structure dynamically and sets it up
712  * to be a "dynamic" kobject with a default release function set up.
713  *
714  * If the kobject was not able to be created, NULL will be returned.
715  * The kobject structure returned from here must be cleaned up with a
716  * call to kobject_put() and not kfree(), as kobject_init() has
717  * already been called on this structure.
718  */
719 struct kobject *kobject_create(void)
720 {
721 	struct kobject *kobj;
722 
723 	kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
724 	if (!kobj)
725 		return NULL;
726 
727 	kobject_init(kobj, &dynamic_kobj_ktype);
728 	return kobj;
729 }
730 
731 /**
732  * kobject_create_and_add - create a struct kobject dynamically and register it with sysfs
733  *
734  * @name: the name for the kobject
735  * @parent: the parent kobject of this kobject, if any.
736  *
737  * This function creates a kobject structure dynamically and registers it
738  * with sysfs.  When you are finished with this structure, call
739  * kobject_put() and the structure will be dynamically freed when
740  * it is no longer being used.
741  *
742  * If the kobject was not able to be created, NULL will be returned.
743  */
744 struct kobject *kobject_create_and_add(const char *name, struct kobject *parent)
745 {
746 	struct kobject *kobj;
747 	int retval;
748 
749 	kobj = kobject_create();
750 	if (!kobj)
751 		return NULL;
752 
753 	retval = kobject_add(kobj, parent, "%s", name);
754 	if (retval) {
755 		printk(KERN_WARNING "%s: kobject_add error: %d\n",
756 		       __func__, retval);
757 		kobject_put(kobj);
758 		kobj = NULL;
759 	}
760 	return kobj;
761 }
762 EXPORT_SYMBOL_GPL(kobject_create_and_add);
763 
764 /**
765  * kset_init - initialize a kset for use
766  * @k: kset
767  */
768 void kset_init(struct kset *k)
769 {
770 	kobject_init_internal(&k->kobj);
771 	INIT_LIST_HEAD(&k->list);
772 	spin_lock_init(&k->list_lock);
773 }
774 
775 /* default kobject attribute operations */
776 static ssize_t kobj_attr_show(struct kobject *kobj, struct attribute *attr,
777 			      char *buf)
778 {
779 	struct kobj_attribute *kattr;
780 	ssize_t ret = -EIO;
781 
782 	kattr = container_of(attr, struct kobj_attribute, attr);
783 	if (kattr->show)
784 		ret = kattr->show(kobj, kattr, buf);
785 	return ret;
786 }
787 
788 static ssize_t kobj_attr_store(struct kobject *kobj, struct attribute *attr,
789 			       const char *buf, size_t count)
790 {
791 	struct kobj_attribute *kattr;
792 	ssize_t ret = -EIO;
793 
794 	kattr = container_of(attr, struct kobj_attribute, attr);
795 	if (kattr->store)
796 		ret = kattr->store(kobj, kattr, buf, count);
797 	return ret;
798 }
799 
800 const struct sysfs_ops kobj_sysfs_ops = {
801 	.show	= kobj_attr_show,
802 	.store	= kobj_attr_store,
803 };
804 EXPORT_SYMBOL_GPL(kobj_sysfs_ops);
805 
806 /**
807  * kset_register - initialize and add a kset.
808  * @k: kset.
809  */
810 int kset_register(struct kset *k)
811 {
812 	int err;
813 
814 	if (!k)
815 		return -EINVAL;
816 
817 	kset_init(k);
818 	err = kobject_add_internal(&k->kobj);
819 	if (err)
820 		return err;
821 	kobject_uevent(&k->kobj, KOBJ_ADD);
822 	return 0;
823 }
824 EXPORT_SYMBOL(kset_register);
825 
826 /**
827  * kset_unregister - remove a kset.
828  * @k: kset.
829  */
830 void kset_unregister(struct kset *k)
831 {
832 	if (!k)
833 		return;
834 	kobject_del(&k->kobj);
835 	kobject_put(&k->kobj);
836 }
837 EXPORT_SYMBOL(kset_unregister);
838 
839 /**
840  * kset_find_obj - search for object in kset.
841  * @kset: kset we're looking in.
842  * @name: object's name.
843  *
844  * Lock kset via @kset->subsys, and iterate over @kset->list,
845  * looking for a matching kobject. If matching object is found
846  * take a reference and return the object.
847  */
848 struct kobject *kset_find_obj(struct kset *kset, const char *name)
849 {
850 	struct kobject *k;
851 	struct kobject *ret = NULL;
852 
853 	spin_lock(&kset->list_lock);
854 
855 	list_for_each_entry(k, &kset->list, entry) {
856 		if (kobject_name(k) && !strcmp(kobject_name(k), name)) {
857 			ret = kobject_get_unless_zero(k);
858 			break;
859 		}
860 	}
861 
862 	spin_unlock(&kset->list_lock);
863 	return ret;
864 }
865 EXPORT_SYMBOL_GPL(kset_find_obj);
866 
867 static void kset_release(struct kobject *kobj)
868 {
869 	struct kset *kset = container_of(kobj, struct kset, kobj);
870 	pr_debug("kobject: '%s' (%p): %s\n",
871 		 kobject_name(kobj), kobj, __func__);
872 	kfree(kset);
873 }
874 
875 static struct kobj_type kset_ktype = {
876 	.sysfs_ops	= &kobj_sysfs_ops,
877 	.release = kset_release,
878 };
879 
880 /**
881  * kset_create - create a struct kset dynamically
882  *
883  * @name: the name for the kset
884  * @uevent_ops: a struct kset_uevent_ops for the kset
885  * @parent_kobj: the parent kobject of this kset, if any.
886  *
887  * This function creates a kset structure dynamically.  This structure can
888  * then be registered with the system and show up in sysfs with a call to
889  * kset_register().  When you are finished with this structure, if
890  * kset_register() has been called, call kset_unregister() and the
891  * structure will be dynamically freed when it is no longer being used.
892  *
893  * If the kset was not able to be created, NULL will be returned.
894  */
895 static struct kset *kset_create(const char *name,
896 				const struct kset_uevent_ops *uevent_ops,
897 				struct kobject *parent_kobj)
898 {
899 	struct kset *kset;
900 	int retval;
901 
902 	kset = kzalloc(sizeof(*kset), GFP_KERNEL);
903 	if (!kset)
904 		return NULL;
905 	retval = kobject_set_name(&kset->kobj, "%s", name);
906 	if (retval) {
907 		kfree(kset);
908 		return NULL;
909 	}
910 	kset->uevent_ops = uevent_ops;
911 	kset->kobj.parent = parent_kobj;
912 
913 	/*
914 	 * The kobject of this kset will have a type of kset_ktype and belong to
915 	 * no kset itself.  That way we can properly free it when it is
916 	 * finished being used.
917 	 */
918 	kset->kobj.ktype = &kset_ktype;
919 	kset->kobj.kset = NULL;
920 
921 	return kset;
922 }
923 
924 /**
925  * kset_create_and_add - create a struct kset dynamically and add it to sysfs
926  *
927  * @name: the name for the kset
928  * @uevent_ops: a struct kset_uevent_ops for the kset
929  * @parent_kobj: the parent kobject of this kset, if any.
930  *
931  * This function creates a kset structure dynamically and registers it
932  * with sysfs.  When you are finished with this structure, call
933  * kset_unregister() and the structure will be dynamically freed when it
934  * is no longer being used.
935  *
936  * If the kset was not able to be created, NULL will be returned.
937  */
938 struct kset *kset_create_and_add(const char *name,
939 				 const struct kset_uevent_ops *uevent_ops,
940 				 struct kobject *parent_kobj)
941 {
942 	struct kset *kset;
943 	int error;
944 
945 	kset = kset_create(name, uevent_ops, parent_kobj);
946 	if (!kset)
947 		return NULL;
948 	error = kset_register(kset);
949 	if (error) {
950 		kfree(kset);
951 		return NULL;
952 	}
953 	return kset;
954 }
955 EXPORT_SYMBOL_GPL(kset_create_and_add);
956 
957 
958 static DEFINE_SPINLOCK(kobj_ns_type_lock);
959 static const struct kobj_ns_type_operations *kobj_ns_ops_tbl[KOBJ_NS_TYPES];
960 
961 int kobj_ns_type_register(const struct kobj_ns_type_operations *ops)
962 {
963 	enum kobj_ns_type type = ops->type;
964 	int error;
965 
966 	spin_lock(&kobj_ns_type_lock);
967 
968 	error = -EINVAL;
969 	if (type >= KOBJ_NS_TYPES)
970 		goto out;
971 
972 	error = -EINVAL;
973 	if (type <= KOBJ_NS_TYPE_NONE)
974 		goto out;
975 
976 	error = -EBUSY;
977 	if (kobj_ns_ops_tbl[type])
978 		goto out;
979 
980 	error = 0;
981 	kobj_ns_ops_tbl[type] = ops;
982 
983 out:
984 	spin_unlock(&kobj_ns_type_lock);
985 	return error;
986 }
987 
988 int kobj_ns_type_registered(enum kobj_ns_type type)
989 {
990 	int registered = 0;
991 
992 	spin_lock(&kobj_ns_type_lock);
993 	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES))
994 		registered = kobj_ns_ops_tbl[type] != NULL;
995 	spin_unlock(&kobj_ns_type_lock);
996 
997 	return registered;
998 }
999 
1000 const struct kobj_ns_type_operations *kobj_child_ns_ops(struct kobject *parent)
1001 {
1002 	const struct kobj_ns_type_operations *ops = NULL;
1003 
1004 	if (parent && parent->ktype && parent->ktype->child_ns_type)
1005 		ops = parent->ktype->child_ns_type(parent);
1006 
1007 	return ops;
1008 }
1009 
1010 const struct kobj_ns_type_operations *kobj_ns_ops(struct kobject *kobj)
1011 {
1012 	return kobj_child_ns_ops(kobj->parent);
1013 }
1014 
1015 bool kobj_ns_current_may_mount(enum kobj_ns_type type)
1016 {
1017 	bool may_mount = true;
1018 
1019 	spin_lock(&kobj_ns_type_lock);
1020 	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1021 	    kobj_ns_ops_tbl[type])
1022 		may_mount = kobj_ns_ops_tbl[type]->current_may_mount();
1023 	spin_unlock(&kobj_ns_type_lock);
1024 
1025 	return may_mount;
1026 }
1027 
1028 void *kobj_ns_grab_current(enum kobj_ns_type type)
1029 {
1030 	void *ns = NULL;
1031 
1032 	spin_lock(&kobj_ns_type_lock);
1033 	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1034 	    kobj_ns_ops_tbl[type])
1035 		ns = kobj_ns_ops_tbl[type]->grab_current_ns();
1036 	spin_unlock(&kobj_ns_type_lock);
1037 
1038 	return ns;
1039 }
1040 EXPORT_SYMBOL_GPL(kobj_ns_grab_current);
1041 
1042 const void *kobj_ns_netlink(enum kobj_ns_type type, struct sock *sk)
1043 {
1044 	const void *ns = NULL;
1045 
1046 	spin_lock(&kobj_ns_type_lock);
1047 	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1048 	    kobj_ns_ops_tbl[type])
1049 		ns = kobj_ns_ops_tbl[type]->netlink_ns(sk);
1050 	spin_unlock(&kobj_ns_type_lock);
1051 
1052 	return ns;
1053 }
1054 
1055 const void *kobj_ns_initial(enum kobj_ns_type type)
1056 {
1057 	const void *ns = NULL;
1058 
1059 	spin_lock(&kobj_ns_type_lock);
1060 	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1061 	    kobj_ns_ops_tbl[type])
1062 		ns = kobj_ns_ops_tbl[type]->initial_ns();
1063 	spin_unlock(&kobj_ns_type_lock);
1064 
1065 	return ns;
1066 }
1067 
1068 void kobj_ns_drop(enum kobj_ns_type type, void *ns)
1069 {
1070 	spin_lock(&kobj_ns_type_lock);
1071 	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1072 	    kobj_ns_ops_tbl[type] && kobj_ns_ops_tbl[type]->drop_ns)
1073 		kobj_ns_ops_tbl[type]->drop_ns(ns);
1074 	spin_unlock(&kobj_ns_type_lock);
1075 }
1076 EXPORT_SYMBOL_GPL(kobj_ns_drop);
1077