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Linux/lib/kobject.c

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  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/core-api/kobject.rst 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  * kobject_get_ownership() - Get sysfs ownership data for @kobj.
 40  * @kobj: kobject in question
 41  * @uid: kernel user ID for sysfs objects
 42  * @gid: kernel group ID for sysfs objects
 43  *
 44  * Returns initial uid/gid pair that should be used when creating sysfs
 45  * representation of given kobject. Normally used to adjust ownership of
 46  * objects in a container.
 47  */
 48 void kobject_get_ownership(struct kobject *kobj, kuid_t *uid, kgid_t *gid)
 49 {
 50         *uid = GLOBAL_ROOT_UID;
 51         *gid = GLOBAL_ROOT_GID;
 52 
 53         if (kobj->ktype->get_ownership)
 54                 kobj->ktype->get_ownership(kobj, uid, gid);
 55 }
 56 
 57 /*
 58  * populate_dir - populate directory with attributes.
 59  * @kobj: object we're working on.
 60  *
 61  * Most subsystems have a set of default attributes that are associated
 62  * with an object that registers with them.  This is a helper called during
 63  * object registration that loops through the default attributes of the
 64  * subsystem and creates attributes files for them in sysfs.
 65  */
 66 static int populate_dir(struct kobject *kobj)
 67 {
 68         struct kobj_type *t = get_ktype(kobj);
 69         struct attribute *attr;
 70         int error = 0;
 71         int i;
 72 
 73         if (t && t->default_attrs) {
 74                 for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
 75                         error = sysfs_create_file(kobj, attr);
 76                         if (error)
 77                                 break;
 78                 }
 79         }
 80         return error;
 81 }
 82 
 83 static int create_dir(struct kobject *kobj)
 84 {
 85         const struct kobj_type *ktype = get_ktype(kobj);
 86         const struct kobj_ns_type_operations *ops;
 87         int error;
 88 
 89         error = sysfs_create_dir_ns(kobj, kobject_namespace(kobj));
 90         if (error)
 91                 return error;
 92 
 93         error = populate_dir(kobj);
 94         if (error) {
 95                 sysfs_remove_dir(kobj);
 96                 return error;
 97         }
 98 
 99         if (ktype) {
100                 error = sysfs_create_groups(kobj, ktype->default_groups);
101                 if (error) {
102                         sysfs_remove_dir(kobj);
103                         return error;
104                 }
105         }
106 
107         /*
108          * @kobj->sd may be deleted by an ancestor going away.  Hold an
109          * extra reference so that it stays until @kobj is gone.
110          */
111         sysfs_get(kobj->sd);
112 
113         /*
114          * If @kobj has ns_ops, its children need to be filtered based on
115          * their namespace tags.  Enable namespace support on @kobj->sd.
116          */
117         ops = kobj_child_ns_ops(kobj);
118         if (ops) {
119                 BUG_ON(ops->type <= KOBJ_NS_TYPE_NONE);
120                 BUG_ON(ops->type >= KOBJ_NS_TYPES);
121                 BUG_ON(!kobj_ns_type_registered(ops->type));
122 
123                 sysfs_enable_ns(kobj->sd);
124         }
125 
126         return 0;
127 }
128 
129 static int get_kobj_path_length(struct kobject *kobj)
130 {
131         int length = 1;
132         struct kobject *parent = kobj;
133 
134         /* walk up the ancestors until we hit the one pointing to the
135          * root.
136          * Add 1 to strlen for leading '/' of each level.
137          */
138         do {
139                 if (kobject_name(parent) == NULL)
140                         return 0;
141                 length += strlen(kobject_name(parent)) + 1;
142                 parent = parent->parent;
143         } while (parent);
144         return length;
145 }
146 
147 static void fill_kobj_path(struct kobject *kobj, char *path, int length)
148 {
149         struct kobject *parent;
150 
151         --length;
152         for (parent = kobj; parent; parent = parent->parent) {
153                 int cur = strlen(kobject_name(parent));
154                 /* back up enough to print this name with '/' */
155                 length -= cur;
156                 memcpy(path + length, kobject_name(parent), cur);
157                 *(path + --length) = '/';
158         }
159 
160         pr_debug("kobject: '%s' (%p): %s: path = '%s'\n", kobject_name(kobj),
161                  kobj, __func__, path);
162 }
163 
164 /**
165  * kobject_get_path() - Allocate memory and fill in the path for @kobj.
166  * @kobj:       kobject in question, with which to build the path
167  * @gfp_mask:   the allocation type used to allocate the path
168  *
169  * Return: The newly allocated memory, caller must free with kfree().
170  */
171 char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
172 {
173         char *path;
174         int len;
175 
176         len = get_kobj_path_length(kobj);
177         if (len == 0)
178                 return NULL;
179         path = kzalloc(len, gfp_mask);
180         if (!path)
181                 return NULL;
182         fill_kobj_path(kobj, path, len);
183 
184         return path;
185 }
186 EXPORT_SYMBOL_GPL(kobject_get_path);
187 
188 /* add the kobject to its kset's list */
189 static void kobj_kset_join(struct kobject *kobj)
190 {
191         if (!kobj->kset)
192                 return;
193 
194         kset_get(kobj->kset);
195         spin_lock(&kobj->kset->list_lock);
196         list_add_tail(&kobj->entry, &kobj->kset->list);
197         spin_unlock(&kobj->kset->list_lock);
198 }
199 
200 /* remove the kobject from its kset's list */
201 static void kobj_kset_leave(struct kobject *kobj)
202 {
203         if (!kobj->kset)
204                 return;
205 
206         spin_lock(&kobj->kset->list_lock);
207         list_del_init(&kobj->entry);
208         spin_unlock(&kobj->kset->list_lock);
209         kset_put(kobj->kset);
210 }
211 
212 static void kobject_init_internal(struct kobject *kobj)
213 {
214         if (!kobj)
215                 return;
216         kref_init(&kobj->kref);
217         INIT_LIST_HEAD(&kobj->entry);
218         kobj->state_in_sysfs = 0;
219         kobj->state_add_uevent_sent = 0;
220         kobj->state_remove_uevent_sent = 0;
221         kobj->state_initialized = 1;
222 }
223 
224 
225 static int kobject_add_internal(struct kobject *kobj)
226 {
227         int error = 0;
228         struct kobject *parent;
229 
230         if (!kobj)
231                 return -ENOENT;
232 
233         if (!kobj->name || !kobj->name[0]) {
234                 WARN(1,
235                      "kobject: (%p): attempted to be registered with empty name!\n",
236                      kobj);
237                 return -EINVAL;
238         }
239 
240         parent = kobject_get(kobj->parent);
241 
242         /* join kset if set, use it as parent if we do not already have one */
243         if (kobj->kset) {
244                 if (!parent)
245                         parent = kobject_get(&kobj->kset->kobj);
246                 kobj_kset_join(kobj);
247                 kobj->parent = parent;
248         }
249 
250         pr_debug("kobject: '%s' (%p): %s: parent: '%s', set: '%s'\n",
251                  kobject_name(kobj), kobj, __func__,
252                  parent ? kobject_name(parent) : "<NULL>",
253                  kobj->kset ? kobject_name(&kobj->kset->kobj) : "<NULL>");
254 
255         error = create_dir(kobj);
256         if (error) {
257                 kobj_kset_leave(kobj);
258                 kobject_put(parent);
259                 kobj->parent = NULL;
260 
261                 /* be noisy on error issues */
262                 if (error == -EEXIST)
263                         pr_err("%s failed for %s with -EEXIST, don't try to register things with the same name in the same directory.\n",
264                                __func__, kobject_name(kobj));
265                 else
266                         pr_err("%s failed for %s (error: %d parent: %s)\n",
267                                __func__, kobject_name(kobj), error,
268                                parent ? kobject_name(parent) : "'none'");
269         } else
270                 kobj->state_in_sysfs = 1;
271 
272         return error;
273 }
274 
275 /**
276  * kobject_set_name_vargs() - Set the name of a kobject.
277  * @kobj: struct kobject to set the name of
278  * @fmt: format string used to build the name
279  * @vargs: vargs to format the string.
280  */
281 int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
282                                   va_list vargs)
283 {
284         const char *s;
285 
286         if (kobj->name && !fmt)
287                 return 0;
288 
289         s = kvasprintf_const(GFP_KERNEL, fmt, vargs);
290         if (!s)
291                 return -ENOMEM;
292 
293         /*
294          * ewww... some of these buggers have '/' in the name ... If
295          * that's the case, we need to make sure we have an actual
296          * allocated copy to modify, since kvasprintf_const may have
297          * returned something from .rodata.
298          */
299         if (strchr(s, '/')) {
300                 char *t;
301 
302                 t = kstrdup(s, GFP_KERNEL);
303                 kfree_const(s);
304                 if (!t)
305                         return -ENOMEM;
306                 strreplace(t, '/', '!');
307                 s = t;
308         }
309         kfree_const(kobj->name);
310         kobj->name = s;
311 
312         return 0;
313 }
314 
315 /**
316  * kobject_set_name() - Set the name of a kobject.
317  * @kobj: struct kobject to set the name of
318  * @fmt: format string used to build the name
319  *
320  * This sets the name of the kobject.  If you have already added the
321  * kobject to the system, you must call kobject_rename() in order to
322  * change the name of the kobject.
323  */
324 int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
325 {
326         va_list vargs;
327         int retval;
328 
329         va_start(vargs, fmt);
330         retval = kobject_set_name_vargs(kobj, fmt, vargs);
331         va_end(vargs);
332 
333         return retval;
334 }
335 EXPORT_SYMBOL(kobject_set_name);
336 
337 /**
338  * kobject_init() - Initialize a kobject structure.
339  * @kobj: pointer to the kobject to initialize
340  * @ktype: pointer to the ktype for this kobject.
341  *
342  * This function will properly initialize a kobject such that it can then
343  * be passed to the kobject_add() call.
344  *
345  * After this function is called, the kobject MUST be cleaned up by a call
346  * to kobject_put(), not by a call to kfree directly to ensure that all of
347  * the memory is cleaned up properly.
348  */
349 void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
350 {
351         char *err_str;
352 
353         if (!kobj) {
354                 err_str = "invalid kobject pointer!";
355                 goto error;
356         }
357         if (!ktype) {
358                 err_str = "must have a ktype to be initialized properly!\n";
359                 goto error;
360         }
361         if (kobj->state_initialized) {
362                 /* do not error out as sometimes we can recover */
363                 pr_err("kobject (%p): tried to init an initialized object, something is seriously wrong.\n",
364                        kobj);
365                 dump_stack();
366         }
367 
368         kobject_init_internal(kobj);
369         kobj->ktype = ktype;
370         return;
371 
372 error:
373         pr_err("kobject (%p): %s\n", kobj, err_str);
374         dump_stack();
375 }
376 EXPORT_SYMBOL(kobject_init);
377 
378 static __printf(3, 0) int kobject_add_varg(struct kobject *kobj,
379                                            struct kobject *parent,
380                                            const char *fmt, va_list vargs)
381 {
382         int retval;
383 
384         retval = kobject_set_name_vargs(kobj, fmt, vargs);
385         if (retval) {
386                 pr_err("kobject: can not set name properly!\n");
387                 return retval;
388         }
389         kobj->parent = parent;
390         return kobject_add_internal(kobj);
391 }
392 
393 /**
394  * kobject_add() - The main kobject add function.
395  * @kobj: the kobject to add
396  * @parent: pointer to the parent of the kobject.
397  * @fmt: format to name the kobject with.
398  *
399  * The kobject name is set and added to the kobject hierarchy in this
400  * function.
401  *
402  * If @parent is set, then the parent of the @kobj will be set to it.
403  * If @parent is NULL, then the parent of the @kobj will be set to the
404  * kobject associated with the kset assigned to this kobject.  If no kset
405  * is assigned to the kobject, then the kobject will be located in the
406  * root of the sysfs tree.
407  *
408  * Note, no "add" uevent will be created with this call, the caller should set
409  * up all of the necessary sysfs files for the object and then call
410  * kobject_uevent() with the UEVENT_ADD parameter to ensure that
411  * userspace is properly notified of this kobject's creation.
412  *
413  * Return: If this function returns an error, kobject_put() must be
414  *         called to properly clean up the memory associated with the
415  *         object.  Under no instance should the kobject that is passed
416  *         to this function be directly freed with a call to kfree(),
417  *         that can leak memory.
418  *
419  *         If this function returns success, kobject_put() must also be called
420  *         in order to properly clean up the memory associated with the object.
421  *
422  *         In short, once this function is called, kobject_put() MUST be called
423  *         when the use of the object is finished in order to properly free
424  *         everything.
425  */
426 int kobject_add(struct kobject *kobj, struct kobject *parent,
427                 const char *fmt, ...)
428 {
429         va_list args;
430         int retval;
431 
432         if (!kobj)
433                 return -EINVAL;
434 
435         if (!kobj->state_initialized) {
436                 pr_err("kobject '%s' (%p): tried to add an uninitialized object, something is seriously wrong.\n",
437                        kobject_name(kobj), kobj);
438                 dump_stack();
439                 return -EINVAL;
440         }
441         va_start(args, fmt);
442         retval = kobject_add_varg(kobj, parent, fmt, args);
443         va_end(args);
444 
445         return retval;
446 }
447 EXPORT_SYMBOL(kobject_add);
448 
449 /**
450  * kobject_init_and_add() - Initialize a kobject structure and add it to
451  *                          the kobject hierarchy.
452  * @kobj: pointer to the kobject to initialize
453  * @ktype: pointer to the ktype for this kobject.
454  * @parent: pointer to the parent of this kobject.
455  * @fmt: the name of the kobject.
456  *
457  * This function combines the call to kobject_init() and kobject_add().
458  *
459  * If this function returns an error, kobject_put() must be called to
460  * properly clean up the memory associated with the object.  This is the
461  * same type of error handling after a call to kobject_add() and kobject
462  * lifetime rules are the same here.
463  */
464 int kobject_init_and_add(struct kobject *kobj, struct kobj_type *ktype,
465                          struct kobject *parent, const char *fmt, ...)
466 {
467         va_list args;
468         int retval;
469 
470         kobject_init(kobj, ktype);
471 
472         va_start(args, fmt);
473         retval = kobject_add_varg(kobj, parent, fmt, args);
474         va_end(args);
475 
476         return retval;
477 }
478 EXPORT_SYMBOL_GPL(kobject_init_and_add);
479 
480 /**
481  * kobject_rename() - Change the name of an object.
482  * @kobj: object in question.
483  * @new_name: object's new name
484  *
485  * It is the responsibility of the caller to provide mutual
486  * exclusion between two different calls of kobject_rename
487  * on the same kobject and to ensure that new_name is valid and
488  * won't conflict with other kobjects.
489  */
490 int kobject_rename(struct kobject *kobj, const char *new_name)
491 {
492         int error = 0;
493         const char *devpath = NULL;
494         const char *dup_name = NULL, *name;
495         char *devpath_string = NULL;
496         char *envp[2];
497 
498         kobj = kobject_get(kobj);
499         if (!kobj)
500                 return -EINVAL;
501         if (!kobj->parent) {
502                 kobject_put(kobj);
503                 return -EINVAL;
504         }
505 
506         devpath = kobject_get_path(kobj, GFP_KERNEL);
507         if (!devpath) {
508                 error = -ENOMEM;
509                 goto out;
510         }
511         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
512         if (!devpath_string) {
513                 error = -ENOMEM;
514                 goto out;
515         }
516         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
517         envp[0] = devpath_string;
518         envp[1] = NULL;
519 
520         name = dup_name = kstrdup_const(new_name, GFP_KERNEL);
521         if (!name) {
522                 error = -ENOMEM;
523                 goto out;
524         }
525 
526         error = sysfs_rename_dir_ns(kobj, new_name, kobject_namespace(kobj));
527         if (error)
528                 goto out;
529 
530         /* Install the new kobject name */
531         dup_name = kobj->name;
532         kobj->name = name;
533 
534         /* This function is mostly/only used for network interface.
535          * Some hotplug package track interfaces by their name and
536          * therefore want to know when the name is changed by the user. */
537         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
538 
539 out:
540         kfree_const(dup_name);
541         kfree(devpath_string);
542         kfree(devpath);
543         kobject_put(kobj);
544 
545         return error;
546 }
547 EXPORT_SYMBOL_GPL(kobject_rename);
548 
549 /**
550  * kobject_move() - Move object to another parent.
551  * @kobj: object in question.
552  * @new_parent: object's new parent (can be NULL)
553  */
554 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
555 {
556         int error;
557         struct kobject *old_parent;
558         const char *devpath = NULL;
559         char *devpath_string = NULL;
560         char *envp[2];
561 
562         kobj = kobject_get(kobj);
563         if (!kobj)
564                 return -EINVAL;
565         new_parent = kobject_get(new_parent);
566         if (!new_parent) {
567                 if (kobj->kset)
568                         new_parent = kobject_get(&kobj->kset->kobj);
569         }
570 
571         /* old object path */
572         devpath = kobject_get_path(kobj, GFP_KERNEL);
573         if (!devpath) {
574                 error = -ENOMEM;
575                 goto out;
576         }
577         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
578         if (!devpath_string) {
579                 error = -ENOMEM;
580                 goto out;
581         }
582         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
583         envp[0] = devpath_string;
584         envp[1] = NULL;
585         error = sysfs_move_dir_ns(kobj, new_parent, kobject_namespace(kobj));
586         if (error)
587                 goto out;
588         old_parent = kobj->parent;
589         kobj->parent = new_parent;
590         new_parent = NULL;
591         kobject_put(old_parent);
592         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
593 out:
594         kobject_put(new_parent);
595         kobject_put(kobj);
596         kfree(devpath_string);
597         kfree(devpath);
598         return error;
599 }
600 EXPORT_SYMBOL_GPL(kobject_move);
601 
602 static void __kobject_del(struct kobject *kobj)
603 {
604         struct kernfs_node *sd;
605         const struct kobj_type *ktype;
606 
607         sd = kobj->sd;
608         ktype = get_ktype(kobj);
609 
610         if (ktype)
611                 sysfs_remove_groups(kobj, ktype->default_groups);
612 
613         /* send "remove" if the caller did not do it but sent "add" */
614         if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
615                 pr_debug("kobject: '%s' (%p): auto cleanup 'remove' event\n",
616                          kobject_name(kobj), kobj);
617                 kobject_uevent(kobj, KOBJ_REMOVE);
618         }
619 
620         sysfs_remove_dir(kobj);
621         sysfs_put(sd);
622 
623         kobj->state_in_sysfs = 0;
624         kobj_kset_leave(kobj);
625         kobj->parent = NULL;
626 }
627 
628 /**
629  * kobject_del() - Unlink kobject from hierarchy.
630  * @kobj: object.
631  *
632  * This is the function that should be called to delete an object
633  * successfully added via kobject_add().
634  */
635 void kobject_del(struct kobject *kobj)
636 {
637         struct kobject *parent;
638 
639         if (!kobj)
640                 return;
641 
642         parent = kobj->parent;
643         __kobject_del(kobj);
644         kobject_put(parent);
645 }
646 EXPORT_SYMBOL(kobject_del);
647 
648 /**
649  * kobject_get() - Increment refcount for object.
650  * @kobj: object.
651  */
652 struct kobject *kobject_get(struct kobject *kobj)
653 {
654         if (kobj) {
655                 if (!kobj->state_initialized)
656                         WARN(1, KERN_WARNING
657                                 "kobject: '%s' (%p): is not initialized, yet kobject_get() is being called.\n",
658                              kobject_name(kobj), kobj);
659                 kref_get(&kobj->kref);
660         }
661         return kobj;
662 }
663 EXPORT_SYMBOL(kobject_get);
664 
665 struct kobject * __must_check kobject_get_unless_zero(struct kobject *kobj)
666 {
667         if (!kobj)
668                 return NULL;
669         if (!kref_get_unless_zero(&kobj->kref))
670                 kobj = NULL;
671         return kobj;
672 }
673 EXPORT_SYMBOL(kobject_get_unless_zero);
674 
675 /*
676  * kobject_cleanup - free kobject resources.
677  * @kobj: object to cleanup
678  */
679 static void kobject_cleanup(struct kobject *kobj)
680 {
681         struct kobject *parent = kobj->parent;
682         struct kobj_type *t = get_ktype(kobj);
683         const char *name = kobj->name;
684 
685         pr_debug("kobject: '%s' (%p): %s, parent %p\n",
686                  kobject_name(kobj), kobj, __func__, kobj->parent);
687 
688         if (t && !t->release)
689                 pr_debug("kobject: '%s' (%p): does not have a release() function, it is broken and must be fixed. See Documentation/core-api/kobject.rst.\n",
690                          kobject_name(kobj), kobj);
691 
692         /* remove from sysfs if the caller did not do it */
693         if (kobj->state_in_sysfs) {
694                 pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n",
695                          kobject_name(kobj), kobj);
696                 __kobject_del(kobj);
697         } else {
698                 /* avoid dropping the parent reference unnecessarily */
699                 parent = NULL;
700         }
701 
702         if (t && t->release) {
703                 pr_debug("kobject: '%s' (%p): calling ktype release\n",
704                          kobject_name(kobj), kobj);
705                 t->release(kobj);
706         }
707 
708         /* free name if we allocated it */
709         if (name) {
710                 pr_debug("kobject: '%s': free name\n", name);
711                 kfree_const(name);
712         }
713 
714         kobject_put(parent);
715 }
716 
717 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
718 static void kobject_delayed_cleanup(struct work_struct *work)
719 {
720         kobject_cleanup(container_of(to_delayed_work(work),
721                                      struct kobject, release));
722 }
723 #endif
724 
725 static void kobject_release(struct kref *kref)
726 {
727         struct kobject *kobj = container_of(kref, struct kobject, kref);
728 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
729         unsigned long delay = HZ + HZ * (get_random_int() & 0x3);
730         pr_info("kobject: '%s' (%p): %s, parent %p (delayed %ld)\n",
731                  kobject_name(kobj), kobj, __func__, kobj->parent, delay);
732         INIT_DELAYED_WORK(&kobj->release, kobject_delayed_cleanup);
733 
734         schedule_delayed_work(&kobj->release, delay);
735 #else
736         kobject_cleanup(kobj);
737 #endif
738 }
739 
740 /**
741  * kobject_put() - Decrement refcount for object.
742  * @kobj: object.
743  *
744  * Decrement the refcount, and if 0, call kobject_cleanup().
745  */
746 void kobject_put(struct kobject *kobj)
747 {
748         if (kobj) {
749                 if (!kobj->state_initialized)
750                         WARN(1, KERN_WARNING
751                                 "kobject: '%s' (%p): is not initialized, yet kobject_put() is being called.\n",
752                              kobject_name(kobj), kobj);
753                 kref_put(&kobj->kref, kobject_release);
754         }
755 }
756 EXPORT_SYMBOL(kobject_put);
757 
758 static void dynamic_kobj_release(struct kobject *kobj)
759 {
760         pr_debug("kobject: (%p): %s\n", kobj, __func__);
761         kfree(kobj);
762 }
763 
764 static struct kobj_type dynamic_kobj_ktype = {
765         .release        = dynamic_kobj_release,
766         .sysfs_ops      = &kobj_sysfs_ops,
767 };
768 
769 /**
770  * kobject_create() - Create a struct kobject dynamically.
771  *
772  * This function creates a kobject structure dynamically and sets it up
773  * to be a "dynamic" kobject with a default release function set up.
774  *
775  * If the kobject was not able to be created, NULL will be returned.
776  * The kobject structure returned from here must be cleaned up with a
777  * call to kobject_put() and not kfree(), as kobject_init() has
778  * already been called on this structure.
779  */
780 struct kobject *kobject_create(void)
781 {
782         struct kobject *kobj;
783 
784         kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
785         if (!kobj)
786                 return NULL;
787 
788         kobject_init(kobj, &dynamic_kobj_ktype);
789         return kobj;
790 }
791 
792 /**
793  * kobject_create_and_add() - Create a struct kobject dynamically and
794  *                            register it with sysfs.
795  * @name: the name for the kobject
796  * @parent: the parent kobject of this kobject, if any.
797  *
798  * This function creates a kobject structure dynamically and registers it
799  * with sysfs.  When you are finished with this structure, call
800  * kobject_put() and the structure will be dynamically freed when
801  * it is no longer being used.
802  *
803  * If the kobject was not able to be created, NULL will be returned.
804  */
805 struct kobject *kobject_create_and_add(const char *name, struct kobject *parent)
806 {
807         struct kobject *kobj;
808         int retval;
809 
810         kobj = kobject_create();
811         if (!kobj)
812                 return NULL;
813 
814         retval = kobject_add(kobj, parent, "%s", name);
815         if (retval) {
816                 pr_warn("%s: kobject_add error: %d\n", __func__, retval);
817                 kobject_put(kobj);
818                 kobj = NULL;
819         }
820         return kobj;
821 }
822 EXPORT_SYMBOL_GPL(kobject_create_and_add);
823 
824 /**
825  * kset_init() - Initialize a kset for use.
826  * @k: kset
827  */
828 void kset_init(struct kset *k)
829 {
830         kobject_init_internal(&k->kobj);
831         INIT_LIST_HEAD(&k->list);
832         spin_lock_init(&k->list_lock);
833 }
834 
835 /* default kobject attribute operations */
836 static ssize_t kobj_attr_show(struct kobject *kobj, struct attribute *attr,
837                               char *buf)
838 {
839         struct kobj_attribute *kattr;
840         ssize_t ret = -EIO;
841 
842         kattr = container_of(attr, struct kobj_attribute, attr);
843         if (kattr->show)
844                 ret = kattr->show(kobj, kattr, buf);
845         return ret;
846 }
847 
848 static ssize_t kobj_attr_store(struct kobject *kobj, struct attribute *attr,
849                                const char *buf, size_t count)
850 {
851         struct kobj_attribute *kattr;
852         ssize_t ret = -EIO;
853 
854         kattr = container_of(attr, struct kobj_attribute, attr);
855         if (kattr->store)
856                 ret = kattr->store(kobj, kattr, buf, count);
857         return ret;
858 }
859 
860 const struct sysfs_ops kobj_sysfs_ops = {
861         .show   = kobj_attr_show,
862         .store  = kobj_attr_store,
863 };
864 EXPORT_SYMBOL_GPL(kobj_sysfs_ops);
865 
866 /**
867  * kset_register() - Initialize and add a kset.
868  * @k: kset.
869  */
870 int kset_register(struct kset *k)
871 {
872         int err;
873 
874         if (!k)
875                 return -EINVAL;
876 
877         kset_init(k);
878         err = kobject_add_internal(&k->kobj);
879         if (err)
880                 return err;
881         kobject_uevent(&k->kobj, KOBJ_ADD);
882         return 0;
883 }
884 EXPORT_SYMBOL(kset_register);
885 
886 /**
887  * kset_unregister() - Remove a kset.
888  * @k: kset.
889  */
890 void kset_unregister(struct kset *k)
891 {
892         if (!k)
893                 return;
894         kobject_del(&k->kobj);
895         kobject_put(&k->kobj);
896 }
897 EXPORT_SYMBOL(kset_unregister);
898 
899 /**
900  * kset_find_obj() - Search for object in kset.
901  * @kset: kset we're looking in.
902  * @name: object's name.
903  *
904  * Lock kset via @kset->subsys, and iterate over @kset->list,
905  * looking for a matching kobject. If matching object is found
906  * take a reference and return the object.
907  */
908 struct kobject *kset_find_obj(struct kset *kset, const char *name)
909 {
910         struct kobject *k;
911         struct kobject *ret = NULL;
912 
913         spin_lock(&kset->list_lock);
914 
915         list_for_each_entry(k, &kset->list, entry) {
916                 if (kobject_name(k) && !strcmp(kobject_name(k), name)) {
917                         ret = kobject_get_unless_zero(k);
918                         break;
919                 }
920         }
921 
922         spin_unlock(&kset->list_lock);
923         return ret;
924 }
925 EXPORT_SYMBOL_GPL(kset_find_obj);
926 
927 static void kset_release(struct kobject *kobj)
928 {
929         struct kset *kset = container_of(kobj, struct kset, kobj);
930         pr_debug("kobject: '%s' (%p): %s\n",
931                  kobject_name(kobj), kobj, __func__);
932         kfree(kset);
933 }
934 
935 static void kset_get_ownership(struct kobject *kobj, kuid_t *uid, kgid_t *gid)
936 {
937         if (kobj->parent)
938                 kobject_get_ownership(kobj->parent, uid, gid);
939 }
940 
941 static struct kobj_type kset_ktype = {
942         .sysfs_ops      = &kobj_sysfs_ops,
943         .release        = kset_release,
944         .get_ownership  = kset_get_ownership,
945 };
946 
947 /**
948  * kset_create() - Create a struct kset dynamically.
949  *
950  * @name: the name for the kset
951  * @uevent_ops: a struct kset_uevent_ops for the kset
952  * @parent_kobj: the parent kobject of this kset, if any.
953  *
954  * This function creates a kset structure dynamically.  This structure can
955  * then be registered with the system and show up in sysfs with a call to
956  * kset_register().  When you are finished with this structure, if
957  * kset_register() has been called, call kset_unregister() and the
958  * structure will be dynamically freed when it is no longer being used.
959  *
960  * If the kset was not able to be created, NULL will be returned.
961  */
962 static struct kset *kset_create(const char *name,
963                                 const struct kset_uevent_ops *uevent_ops,
964                                 struct kobject *parent_kobj)
965 {
966         struct kset *kset;
967         int retval;
968 
969         kset = kzalloc(sizeof(*kset), GFP_KERNEL);
970         if (!kset)
971                 return NULL;
972         retval = kobject_set_name(&kset->kobj, "%s", name);
973         if (retval) {
974                 kfree(kset);
975                 return NULL;
976         }
977         kset->uevent_ops = uevent_ops;
978         kset->kobj.parent = parent_kobj;
979 
980         /*
981          * The kobject of this kset will have a type of kset_ktype and belong to
982          * no kset itself.  That way we can properly free it when it is
983          * finished being used.
984          */
985         kset->kobj.ktype = &kset_ktype;
986         kset->kobj.kset = NULL;
987 
988         return kset;
989 }
990 
991 /**
992  * kset_create_and_add() - Create a struct kset dynamically and add it to sysfs.
993  *
994  * @name: the name for the kset
995  * @uevent_ops: a struct kset_uevent_ops for the kset
996  * @parent_kobj: the parent kobject of this kset, if any.
997  *
998  * This function creates a kset structure dynamically and registers it
999  * with sysfs.  When you are finished with this structure, call
1000  * kset_unregister() and the structure will be dynamically freed when it
1001  * is no longer being used.
1002  *
1003  * If the kset was not able to be created, NULL will be returned.
1004  */
1005 struct kset *kset_create_and_add(const char *name,
1006                                  const struct kset_uevent_ops *uevent_ops,
1007                                  struct kobject *parent_kobj)
1008 {
1009         struct kset *kset;
1010         int error;
1011 
1012         kset = kset_create(name, uevent_ops, parent_kobj);
1013         if (!kset)
1014                 return NULL;
1015         error = kset_register(kset);
1016         if (error) {
1017                 kfree(kset);
1018                 return NULL;
1019         }
1020         return kset;
1021 }
1022 EXPORT_SYMBOL_GPL(kset_create_and_add);
1023 
1024 
1025 static DEFINE_SPINLOCK(kobj_ns_type_lock);
1026 static const struct kobj_ns_type_operations *kobj_ns_ops_tbl[KOBJ_NS_TYPES];
1027 
1028 int kobj_ns_type_register(const struct kobj_ns_type_operations *ops)
1029 {
1030         enum kobj_ns_type type = ops->type;
1031         int error;
1032 
1033         spin_lock(&kobj_ns_type_lock);
1034 
1035         error = -EINVAL;
1036         if (type >= KOBJ_NS_TYPES)
1037                 goto out;
1038 
1039         error = -EINVAL;
1040         if (type <= KOBJ_NS_TYPE_NONE)
1041                 goto out;
1042 
1043         error = -EBUSY;
1044         if (kobj_ns_ops_tbl[type])
1045                 goto out;
1046 
1047         error = 0;
1048         kobj_ns_ops_tbl[type] = ops;
1049 
1050 out:
1051         spin_unlock(&kobj_ns_type_lock);
1052         return error;
1053 }
1054 
1055 int kobj_ns_type_registered(enum kobj_ns_type type)
1056 {
1057         int registered = 0;
1058 
1059         spin_lock(&kobj_ns_type_lock);
1060         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES))
1061                 registered = kobj_ns_ops_tbl[type] != NULL;
1062         spin_unlock(&kobj_ns_type_lock);
1063 
1064         return registered;
1065 }
1066 
1067 const struct kobj_ns_type_operations *kobj_child_ns_ops(struct kobject *parent)
1068 {
1069         const struct kobj_ns_type_operations *ops = NULL;
1070 
1071         if (parent && parent->ktype && parent->ktype->child_ns_type)
1072                 ops = parent->ktype->child_ns_type(parent);
1073 
1074         return ops;
1075 }
1076 
1077 const struct kobj_ns_type_operations *kobj_ns_ops(struct kobject *kobj)
1078 {
1079         return kobj_child_ns_ops(kobj->parent);
1080 }
1081 
1082 bool kobj_ns_current_may_mount(enum kobj_ns_type type)
1083 {
1084         bool may_mount = true;
1085 
1086         spin_lock(&kobj_ns_type_lock);
1087         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1088             kobj_ns_ops_tbl[type])
1089                 may_mount = kobj_ns_ops_tbl[type]->current_may_mount();
1090         spin_unlock(&kobj_ns_type_lock);
1091 
1092         return may_mount;
1093 }
1094 
1095 void *kobj_ns_grab_current(enum kobj_ns_type type)
1096 {
1097         void *ns = NULL;
1098 
1099         spin_lock(&kobj_ns_type_lock);
1100         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1101             kobj_ns_ops_tbl[type])
1102                 ns = kobj_ns_ops_tbl[type]->grab_current_ns();
1103         spin_unlock(&kobj_ns_type_lock);
1104 
1105         return ns;
1106 }
1107 EXPORT_SYMBOL_GPL(kobj_ns_grab_current);
1108 
1109 const void *kobj_ns_netlink(enum kobj_ns_type type, struct sock *sk)
1110 {
1111         const void *ns = NULL;
1112 
1113         spin_lock(&kobj_ns_type_lock);
1114         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1115             kobj_ns_ops_tbl[type])
1116                 ns = kobj_ns_ops_tbl[type]->netlink_ns(sk);
1117         spin_unlock(&kobj_ns_type_lock);
1118 
1119         return ns;
1120 }
1121 
1122 const void *kobj_ns_initial(enum kobj_ns_type type)
1123 {
1124         const void *ns = NULL;
1125 
1126         spin_lock(&kobj_ns_type_lock);
1127         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1128             kobj_ns_ops_tbl[type])
1129                 ns = kobj_ns_ops_tbl[type]->initial_ns();
1130         spin_unlock(&kobj_ns_type_lock);
1131 
1132         return ns;
1133 }
1134 
1135 void kobj_ns_drop(enum kobj_ns_type type, void *ns)
1136 {
1137         spin_lock(&kobj_ns_type_lock);
1138         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1139             kobj_ns_ops_tbl[type] && kobj_ns_ops_tbl[type]->drop_ns)
1140                 kobj_ns_ops_tbl[type]->drop_ns(ns);
1141         spin_unlock(&kobj_ns_type_lock);
1142 }
1143 EXPORT_SYMBOL_GPL(kobj_ns_drop);
1144 

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