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TOMOYO Linux Cross Reference
Linux/lib/kobject.c

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  1 /*
  2  * kobject.c - library routines for handling generic kernel objects
  3  *
  4  * Copyright (c) 2002-2003 Patrick Mochel <mochel@osdl.org>
  5  * Copyright (c) 2006-2007 Greg Kroah-Hartman <greg@kroah.com>
  6  * Copyright (c) 2006-2007 Novell Inc.
  7  *
  8  * This file is released under the GPLv2.
  9  *
 10  *
 11  * Please see the file Documentation/kobject.txt for critical information
 12  * about using the kobject interface.
 13  */
 14 
 15 #include <linux/kobject.h>
 16 #include <linux/string.h>
 17 #include <linux/export.h>
 18 #include <linux/stat.h>
 19 #include <linux/slab.h>
 20 #include <linux/random.h>
 21 
 22 /**
 23  * kobject_namespace - return @kobj's namespace tag
 24  * @kobj: kobject in question
 25  *
 26  * Returns namespace tag of @kobj if its parent has namespace ops enabled
 27  * and thus @kobj should have a namespace tag associated with it.  Returns
 28  * %NULL otherwise.
 29  */
 30 const void *kobject_namespace(struct kobject *kobj)
 31 {
 32         const struct kobj_ns_type_operations *ns_ops = kobj_ns_ops(kobj);
 33 
 34         if (!ns_ops || ns_ops->type == KOBJ_NS_TYPE_NONE)
 35                 return NULL;
 36 
 37         return kobj->ktype->namespace(kobj);
 38 }
 39 
 40 /*
 41  * populate_dir - populate directory with attributes.
 42  * @kobj: object we're working on.
 43  *
 44  * Most subsystems have a set of default attributes that are associated
 45  * with an object that registers with them.  This is a helper called during
 46  * object registration that loops through the default attributes of the
 47  * subsystem and creates attributes files for them in sysfs.
 48  */
 49 static int populate_dir(struct kobject *kobj)
 50 {
 51         struct kobj_type *t = get_ktype(kobj);
 52         struct attribute *attr;
 53         int error = 0;
 54         int i;
 55 
 56         if (t && t->default_attrs) {
 57                 for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
 58                         error = sysfs_create_file(kobj, attr);
 59                         if (error)
 60                                 break;
 61                 }
 62         }
 63         return error;
 64 }
 65 
 66 static int create_dir(struct kobject *kobj)
 67 {
 68         const struct kobj_ns_type_operations *ops;
 69         int error;
 70 
 71         error = sysfs_create_dir_ns(kobj, kobject_namespace(kobj));
 72         if (error)
 73                 return error;
 74 
 75         error = populate_dir(kobj);
 76         if (error) {
 77                 sysfs_remove_dir(kobj);
 78                 return error;
 79         }
 80 
 81         /*
 82          * @kobj->sd may be deleted by an ancestor going away.  Hold an
 83          * extra reference so that it stays until @kobj is gone.
 84          */
 85         sysfs_get(kobj->sd);
 86 
 87         /*
 88          * If @kobj has ns_ops, its children need to be filtered based on
 89          * their namespace tags.  Enable namespace support on @kobj->sd.
 90          */
 91         ops = kobj_child_ns_ops(kobj);
 92         if (ops) {
 93                 BUG_ON(ops->type <= KOBJ_NS_TYPE_NONE);
 94                 BUG_ON(ops->type >= KOBJ_NS_TYPES);
 95                 BUG_ON(!kobj_ns_type_registered(ops->type));
 96 
 97                 sysfs_enable_ns(kobj->sd);
 98         }
 99 
100         return 0;
101 }
102 
103 static int get_kobj_path_length(struct kobject *kobj)
104 {
105         int length = 1;
106         struct kobject *parent = kobj;
107 
108         /* walk up the ancestors until we hit the one pointing to the
109          * root.
110          * Add 1 to strlen for leading '/' of each level.
111          */
112         do {
113                 if (kobject_name(parent) == NULL)
114                         return 0;
115                 length += strlen(kobject_name(parent)) + 1;
116                 parent = parent->parent;
117         } while (parent);
118         return length;
119 }
120 
121 static void fill_kobj_path(struct kobject *kobj, char *path, int length)
122 {
123         struct kobject *parent;
124 
125         --length;
126         for (parent = kobj; parent; parent = parent->parent) {
127                 int cur = strlen(kobject_name(parent));
128                 /* back up enough to print this name with '/' */
129                 length -= cur;
130                 strncpy(path + length, kobject_name(parent), cur);
131                 *(path + --length) = '/';
132         }
133 
134         pr_debug("kobject: '%s' (%p): %s: path = '%s'\n", kobject_name(kobj),
135                  kobj, __func__, path);
136 }
137 
138 /**
139  * kobject_get_path - generate and return the path associated with a given kobj and kset pair.
140  *
141  * @kobj:       kobject in question, with which to build the path
142  * @gfp_mask:   the allocation type used to allocate the path
143  *
144  * The result must be freed by the caller with kfree().
145  */
146 char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
147 {
148         char *path;
149         int len;
150 
151         len = get_kobj_path_length(kobj);
152         if (len == 0)
153                 return NULL;
154         path = kzalloc(len, gfp_mask);
155         if (!path)
156                 return NULL;
157         fill_kobj_path(kobj, path, len);
158 
159         return path;
160 }
161 EXPORT_SYMBOL_GPL(kobject_get_path);
162 
163 /* add the kobject to its kset's list */
164 static void kobj_kset_join(struct kobject *kobj)
165 {
166         if (!kobj->kset)
167                 return;
168 
169         kset_get(kobj->kset);
170         spin_lock(&kobj->kset->list_lock);
171         list_add_tail(&kobj->entry, &kobj->kset->list);
172         spin_unlock(&kobj->kset->list_lock);
173 }
174 
175 /* remove the kobject from its kset's list */
176 static void kobj_kset_leave(struct kobject *kobj)
177 {
178         if (!kobj->kset)
179                 return;
180 
181         spin_lock(&kobj->kset->list_lock);
182         list_del_init(&kobj->entry);
183         spin_unlock(&kobj->kset->list_lock);
184         kset_put(kobj->kset);
185 }
186 
187 static void kobject_init_internal(struct kobject *kobj)
188 {
189         if (!kobj)
190                 return;
191         kref_init(&kobj->kref);
192         INIT_LIST_HEAD(&kobj->entry);
193         kobj->state_in_sysfs = 0;
194         kobj->state_add_uevent_sent = 0;
195         kobj->state_remove_uevent_sent = 0;
196         kobj->state_initialized = 1;
197 }
198 
199 
200 static int kobject_add_internal(struct kobject *kobj)
201 {
202         int error = 0;
203         struct kobject *parent;
204 
205         if (!kobj)
206                 return -ENOENT;
207 
208         if (!kobj->name || !kobj->name[0]) {
209                 WARN(1, "kobject: (%p): attempted to be registered with empty "
210                          "name!\n", kobj);
211                 return -EINVAL;
212         }
213 
214         parent = kobject_get(kobj->parent);
215 
216         /* join kset if set, use it as parent if we do not already have one */
217         if (kobj->kset) {
218                 if (!parent)
219                         parent = kobject_get(&kobj->kset->kobj);
220                 kobj_kset_join(kobj);
221                 kobj->parent = parent;
222         }
223 
224         pr_debug("kobject: '%s' (%p): %s: parent: '%s', set: '%s'\n",
225                  kobject_name(kobj), kobj, __func__,
226                  parent ? kobject_name(parent) : "<NULL>",
227                  kobj->kset ? kobject_name(&kobj->kset->kobj) : "<NULL>");
228 
229         error = create_dir(kobj);
230         if (error) {
231                 kobj_kset_leave(kobj);
232                 kobject_put(parent);
233                 kobj->parent = NULL;
234 
235                 /* be noisy on error issues */
236                 if (error == -EEXIST)
237                         WARN(1, "%s failed for %s with "
238                              "-EEXIST, don't try to register things with "
239                              "the same name in the same directory.\n",
240                              __func__, kobject_name(kobj));
241                 else
242                         WARN(1, "%s failed for %s (error: %d parent: %s)\n",
243                              __func__, kobject_name(kobj), error,
244                              parent ? kobject_name(parent) : "'none'");
245         } else
246                 kobj->state_in_sysfs = 1;
247 
248         return error;
249 }
250 
251 /**
252  * kobject_set_name_vargs - Set the name of an kobject
253  * @kobj: struct kobject to set the name of
254  * @fmt: format string used to build the name
255  * @vargs: vargs to format the string.
256  */
257 int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
258                                   va_list vargs)
259 {
260         char *s;
261 
262         if (kobj->name && !fmt)
263                 return 0;
264 
265         s = kvasprintf(GFP_KERNEL, fmt, vargs);
266         if (!s)
267                 return -ENOMEM;
268 
269         /* ewww... some of these buggers have '/' in the name ... */
270         strreplace(s, '/', '!');
271         kfree(kobj->name);
272         kobj->name = s;
273 
274         return 0;
275 }
276 
277 /**
278  * kobject_set_name - Set the name of a kobject
279  * @kobj: struct kobject to set the name of
280  * @fmt: format string used to build the name
281  *
282  * This sets the name of the kobject.  If you have already added the
283  * kobject to the system, you must call kobject_rename() in order to
284  * change the name of the kobject.
285  */
286 int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
287 {
288         va_list vargs;
289         int retval;
290 
291         va_start(vargs, fmt);
292         retval = kobject_set_name_vargs(kobj, fmt, vargs);
293         va_end(vargs);
294 
295         return retval;
296 }
297 EXPORT_SYMBOL(kobject_set_name);
298 
299 /**
300  * kobject_init - initialize a kobject structure
301  * @kobj: pointer to the kobject to initialize
302  * @ktype: pointer to the ktype for this kobject.
303  *
304  * This function will properly initialize a kobject such that it can then
305  * be passed to the kobject_add() call.
306  *
307  * After this function is called, the kobject MUST be cleaned up by a call
308  * to kobject_put(), not by a call to kfree directly to ensure that all of
309  * the memory is cleaned up properly.
310  */
311 void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
312 {
313         char *err_str;
314 
315         if (!kobj) {
316                 err_str = "invalid kobject pointer!";
317                 goto error;
318         }
319         if (!ktype) {
320                 err_str = "must have a ktype to be initialized properly!\n";
321                 goto error;
322         }
323         if (kobj->state_initialized) {
324                 /* do not error out as sometimes we can recover */
325                 printk(KERN_ERR "kobject (%p): tried to init an initialized "
326                        "object, something is seriously wrong.\n", kobj);
327                 dump_stack();
328         }
329 
330         kobject_init_internal(kobj);
331         kobj->ktype = ktype;
332         return;
333 
334 error:
335         printk(KERN_ERR "kobject (%p): %s\n", kobj, err_str);
336         dump_stack();
337 }
338 EXPORT_SYMBOL(kobject_init);
339 
340 static __printf(3, 0) int kobject_add_varg(struct kobject *kobj,
341                                            struct kobject *parent,
342                                            const char *fmt, va_list vargs)
343 {
344         int retval;
345 
346         retval = kobject_set_name_vargs(kobj, fmt, vargs);
347         if (retval) {
348                 printk(KERN_ERR "kobject: can not set name properly!\n");
349                 return retval;
350         }
351         kobj->parent = parent;
352         return kobject_add_internal(kobj);
353 }
354 
355 /**
356  * kobject_add - the main kobject add function
357  * @kobj: the kobject to add
358  * @parent: pointer to the parent of the kobject.
359  * @fmt: format to name the kobject with.
360  *
361  * The kobject name is set and added to the kobject hierarchy in this
362  * function.
363  *
364  * If @parent is set, then the parent of the @kobj will be set to it.
365  * If @parent is NULL, then the parent of the @kobj will be set to the
366  * kobject associated with the kset assigned to this kobject.  If no kset
367  * is assigned to the kobject, then the kobject will be located in the
368  * root of the sysfs tree.
369  *
370  * If this function returns an error, kobject_put() must be called to
371  * properly clean up the memory associated with the object.
372  * Under no instance should the kobject that is passed to this function
373  * be directly freed with a call to kfree(), that can leak memory.
374  *
375  * Note, no "add" uevent will be created with this call, the caller should set
376  * up all of the necessary sysfs files for the object and then call
377  * kobject_uevent() with the UEVENT_ADD parameter to ensure that
378  * userspace is properly notified of this kobject's creation.
379  */
380 int kobject_add(struct kobject *kobj, struct kobject *parent,
381                 const char *fmt, ...)
382 {
383         va_list args;
384         int retval;
385 
386         if (!kobj)
387                 return -EINVAL;
388 
389         if (!kobj->state_initialized) {
390                 printk(KERN_ERR "kobject '%s' (%p): tried to add an "
391                        "uninitialized object, something is seriously wrong.\n",
392                        kobject_name(kobj), kobj);
393                 dump_stack();
394                 return -EINVAL;
395         }
396         va_start(args, fmt);
397         retval = kobject_add_varg(kobj, parent, fmt, args);
398         va_end(args);
399 
400         return retval;
401 }
402 EXPORT_SYMBOL(kobject_add);
403 
404 /**
405  * kobject_init_and_add - initialize a kobject structure and add it to the kobject hierarchy
406  * @kobj: pointer to the kobject to initialize
407  * @ktype: pointer to the ktype for this kobject.
408  * @parent: pointer to the parent of this kobject.
409  * @fmt: the name of the kobject.
410  *
411  * This function combines the call to kobject_init() and
412  * kobject_add().  The same type of error handling after a call to
413  * kobject_add() and kobject lifetime rules are the same here.
414  */
415 int kobject_init_and_add(struct kobject *kobj, struct kobj_type *ktype,
416                          struct kobject *parent, const char *fmt, ...)
417 {
418         va_list args;
419         int retval;
420 
421         kobject_init(kobj, ktype);
422 
423         va_start(args, fmt);
424         retval = kobject_add_varg(kobj, parent, fmt, args);
425         va_end(args);
426 
427         return retval;
428 }
429 EXPORT_SYMBOL_GPL(kobject_init_and_add);
430 
431 /**
432  * kobject_rename - change the name of an object
433  * @kobj: object in question.
434  * @new_name: object's new name
435  *
436  * It is the responsibility of the caller to provide mutual
437  * exclusion between two different calls of kobject_rename
438  * on the same kobject and to ensure that new_name is valid and
439  * won't conflict with other kobjects.
440  */
441 int kobject_rename(struct kobject *kobj, const char *new_name)
442 {
443         int error = 0;
444         const char *devpath = NULL;
445         const char *dup_name = NULL, *name;
446         char *devpath_string = NULL;
447         char *envp[2];
448 
449         kobj = kobject_get(kobj);
450         if (!kobj)
451                 return -EINVAL;
452         if (!kobj->parent)
453                 return -EINVAL;
454 
455         devpath = kobject_get_path(kobj, GFP_KERNEL);
456         if (!devpath) {
457                 error = -ENOMEM;
458                 goto out;
459         }
460         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
461         if (!devpath_string) {
462                 error = -ENOMEM;
463                 goto out;
464         }
465         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
466         envp[0] = devpath_string;
467         envp[1] = NULL;
468 
469         name = dup_name = kstrdup(new_name, GFP_KERNEL);
470         if (!name) {
471                 error = -ENOMEM;
472                 goto out;
473         }
474 
475         error = sysfs_rename_dir_ns(kobj, new_name, kobject_namespace(kobj));
476         if (error)
477                 goto out;
478 
479         /* Install the new kobject name */
480         dup_name = kobj->name;
481         kobj->name = name;
482 
483         /* This function is mostly/only used for network interface.
484          * Some hotplug package track interfaces by their name and
485          * therefore want to know when the name is changed by the user. */
486         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
487 
488 out:
489         kfree(dup_name);
490         kfree(devpath_string);
491         kfree(devpath);
492         kobject_put(kobj);
493 
494         return error;
495 }
496 EXPORT_SYMBOL_GPL(kobject_rename);
497 
498 /**
499  * kobject_move - move object to another parent
500  * @kobj: object in question.
501  * @new_parent: object's new parent (can be NULL)
502  */
503 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
504 {
505         int error;
506         struct kobject *old_parent;
507         const char *devpath = NULL;
508         char *devpath_string = NULL;
509         char *envp[2];
510 
511         kobj = kobject_get(kobj);
512         if (!kobj)
513                 return -EINVAL;
514         new_parent = kobject_get(new_parent);
515         if (!new_parent) {
516                 if (kobj->kset)
517                         new_parent = kobject_get(&kobj->kset->kobj);
518         }
519 
520         /* old object path */
521         devpath = kobject_get_path(kobj, GFP_KERNEL);
522         if (!devpath) {
523                 error = -ENOMEM;
524                 goto out;
525         }
526         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
527         if (!devpath_string) {
528                 error = -ENOMEM;
529                 goto out;
530         }
531         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
532         envp[0] = devpath_string;
533         envp[1] = NULL;
534         error = sysfs_move_dir_ns(kobj, new_parent, kobject_namespace(kobj));
535         if (error)
536                 goto out;
537         old_parent = kobj->parent;
538         kobj->parent = new_parent;
539         new_parent = NULL;
540         kobject_put(old_parent);
541         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
542 out:
543         kobject_put(new_parent);
544         kobject_put(kobj);
545         kfree(devpath_string);
546         kfree(devpath);
547         return error;
548 }
549 EXPORT_SYMBOL_GPL(kobject_move);
550 
551 /**
552  * kobject_del - unlink kobject from hierarchy.
553  * @kobj: object.
554  */
555 void kobject_del(struct kobject *kobj)
556 {
557         struct kernfs_node *sd;
558 
559         if (!kobj)
560                 return;
561 
562         sd = kobj->sd;
563         sysfs_remove_dir(kobj);
564         sysfs_put(sd);
565 
566         kobj->state_in_sysfs = 0;
567         kobj_kset_leave(kobj);
568         kobject_put(kobj->parent);
569         kobj->parent = NULL;
570 }
571 
572 /**
573  * kobject_get - increment refcount for object.
574  * @kobj: object.
575  */
576 struct kobject *kobject_get(struct kobject *kobj)
577 {
578         if (kobj) {
579                 if (!kobj->state_initialized)
580                         WARN(1, KERN_WARNING "kobject: '%s' (%p): is not "
581                                "initialized, yet kobject_get() is being "
582                                "called.\n", kobject_name(kobj), kobj);
583                 kref_get(&kobj->kref);
584         }
585         return kobj;
586 }
587 
588 static struct kobject * __must_check kobject_get_unless_zero(struct kobject *kobj)
589 {
590         if (!kref_get_unless_zero(&kobj->kref))
591                 kobj = NULL;
592         return kobj;
593 }
594 
595 /*
596  * kobject_cleanup - free kobject resources.
597  * @kobj: object to cleanup
598  */
599 static void kobject_cleanup(struct kobject *kobj)
600 {
601         struct kobj_type *t = get_ktype(kobj);
602         const char *name = kobj->name;
603 
604         pr_debug("kobject: '%s' (%p): %s, parent %p\n",
605                  kobject_name(kobj), kobj, __func__, kobj->parent);
606 
607         if (t && !t->release)
608                 pr_debug("kobject: '%s' (%p): does not have a release() "
609                          "function, it is broken and must be fixed.\n",
610                          kobject_name(kobj), kobj);
611 
612         /* send "remove" if the caller did not do it but sent "add" */
613         if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
614                 pr_debug("kobject: '%s' (%p): auto cleanup 'remove' event\n",
615                          kobject_name(kobj), kobj);
616                 kobject_uevent(kobj, KOBJ_REMOVE);
617         }
618 
619         /* remove from sysfs if the caller did not do it */
620         if (kobj->state_in_sysfs) {
621                 pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n",
622                          kobject_name(kobj), kobj);
623                 kobject_del(kobj);
624         }
625 
626         if (t && t->release) {
627                 pr_debug("kobject: '%s' (%p): calling ktype release\n",
628                          kobject_name(kobj), kobj);
629                 t->release(kobj);
630         }
631 
632         /* free name if we allocated it */
633         if (name) {
634                 pr_debug("kobject: '%s': free name\n", name);
635                 kfree(name);
636         }
637 }
638 
639 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
640 static void kobject_delayed_cleanup(struct work_struct *work)
641 {
642         kobject_cleanup(container_of(to_delayed_work(work),
643                                      struct kobject, release));
644 }
645 #endif
646 
647 static void kobject_release(struct kref *kref)
648 {
649         struct kobject *kobj = container_of(kref, struct kobject, kref);
650 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
651         unsigned long delay = HZ + HZ * (get_random_int() & 0x3);
652         pr_info("kobject: '%s' (%p): %s, parent %p (delayed %ld)\n",
653                  kobject_name(kobj), kobj, __func__, kobj->parent, delay);
654         INIT_DELAYED_WORK(&kobj->release, kobject_delayed_cleanup);
655 
656         schedule_delayed_work(&kobj->release, delay);
657 #else
658         kobject_cleanup(kobj);
659 #endif
660 }
661 
662 /**
663  * kobject_put - decrement refcount for object.
664  * @kobj: object.
665  *
666  * Decrement the refcount, and if 0, call kobject_cleanup().
667  */
668 void kobject_put(struct kobject *kobj)
669 {
670         if (kobj) {
671                 if (!kobj->state_initialized)
672                         WARN(1, KERN_WARNING "kobject: '%s' (%p): is not "
673                                "initialized, yet kobject_put() is being "
674                                "called.\n", kobject_name(kobj), kobj);
675                 kref_put(&kobj->kref, kobject_release);
676         }
677 }
678 
679 static void dynamic_kobj_release(struct kobject *kobj)
680 {
681         pr_debug("kobject: (%p): %s\n", kobj, __func__);
682         kfree(kobj);
683 }
684 
685 static struct kobj_type dynamic_kobj_ktype = {
686         .release        = dynamic_kobj_release,
687         .sysfs_ops      = &kobj_sysfs_ops,
688 };
689 
690 /**
691  * kobject_create - create a struct kobject dynamically
692  *
693  * This function creates a kobject structure dynamically and sets it up
694  * to be a "dynamic" kobject with a default release function set up.
695  *
696  * If the kobject was not able to be created, NULL will be returned.
697  * The kobject structure returned from here must be cleaned up with a
698  * call to kobject_put() and not kfree(), as kobject_init() has
699  * already been called on this structure.
700  */
701 struct kobject *kobject_create(void)
702 {
703         struct kobject *kobj;
704 
705         kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
706         if (!kobj)
707                 return NULL;
708 
709         kobject_init(kobj, &dynamic_kobj_ktype);
710         return kobj;
711 }
712 
713 /**
714  * kobject_create_and_add - create a struct kobject dynamically and register it with sysfs
715  *
716  * @name: the name for the kobject
717  * @parent: the parent kobject of this kobject, if any.
718  *
719  * This function creates a kobject structure dynamically and registers it
720  * with sysfs.  When you are finished with this structure, call
721  * kobject_put() and the structure will be dynamically freed when
722  * it is no longer being used.
723  *
724  * If the kobject was not able to be created, NULL will be returned.
725  */
726 struct kobject *kobject_create_and_add(const char *name, struct kobject *parent)
727 {
728         struct kobject *kobj;
729         int retval;
730 
731         kobj = kobject_create();
732         if (!kobj)
733                 return NULL;
734 
735         retval = kobject_add(kobj, parent, "%s", name);
736         if (retval) {
737                 printk(KERN_WARNING "%s: kobject_add error: %d\n",
738                        __func__, retval);
739                 kobject_put(kobj);
740                 kobj = NULL;
741         }
742         return kobj;
743 }
744 EXPORT_SYMBOL_GPL(kobject_create_and_add);
745 
746 /**
747  * kset_init - initialize a kset for use
748  * @k: kset
749  */
750 void kset_init(struct kset *k)
751 {
752         kobject_init_internal(&k->kobj);
753         INIT_LIST_HEAD(&k->list);
754         spin_lock_init(&k->list_lock);
755 }
756 
757 /* default kobject attribute operations */
758 static ssize_t kobj_attr_show(struct kobject *kobj, struct attribute *attr,
759                               char *buf)
760 {
761         struct kobj_attribute *kattr;
762         ssize_t ret = -EIO;
763 
764         kattr = container_of(attr, struct kobj_attribute, attr);
765         if (kattr->show)
766                 ret = kattr->show(kobj, kattr, buf);
767         return ret;
768 }
769 
770 static ssize_t kobj_attr_store(struct kobject *kobj, struct attribute *attr,
771                                const char *buf, size_t count)
772 {
773         struct kobj_attribute *kattr;
774         ssize_t ret = -EIO;
775 
776         kattr = container_of(attr, struct kobj_attribute, attr);
777         if (kattr->store)
778                 ret = kattr->store(kobj, kattr, buf, count);
779         return ret;
780 }
781 
782 const struct sysfs_ops kobj_sysfs_ops = {
783         .show   = kobj_attr_show,
784         .store  = kobj_attr_store,
785 };
786 EXPORT_SYMBOL_GPL(kobj_sysfs_ops);
787 
788 /**
789  * kset_register - initialize and add a kset.
790  * @k: kset.
791  */
792 int kset_register(struct kset *k)
793 {
794         int err;
795 
796         if (!k)
797                 return -EINVAL;
798 
799         kset_init(k);
800         err = kobject_add_internal(&k->kobj);
801         if (err)
802                 return err;
803         kobject_uevent(&k->kobj, KOBJ_ADD);
804         return 0;
805 }
806 
807 /**
808  * kset_unregister - remove a kset.
809  * @k: kset.
810  */
811 void kset_unregister(struct kset *k)
812 {
813         if (!k)
814                 return;
815         kobject_del(&k->kobj);
816         kobject_put(&k->kobj);
817 }
818 
819 /**
820  * kset_find_obj - search for object in kset.
821  * @kset: kset we're looking in.
822  * @name: object's name.
823  *
824  * Lock kset via @kset->subsys, and iterate over @kset->list,
825  * looking for a matching kobject. If matching object is found
826  * take a reference and return the object.
827  */
828 struct kobject *kset_find_obj(struct kset *kset, const char *name)
829 {
830         struct kobject *k;
831         struct kobject *ret = NULL;
832 
833         spin_lock(&kset->list_lock);
834 
835         list_for_each_entry(k, &kset->list, entry) {
836                 if (kobject_name(k) && !strcmp(kobject_name(k), name)) {
837                         ret = kobject_get_unless_zero(k);
838                         break;
839                 }
840         }
841 
842         spin_unlock(&kset->list_lock);
843         return ret;
844 }
845 
846 static void kset_release(struct kobject *kobj)
847 {
848         struct kset *kset = container_of(kobj, struct kset, kobj);
849         pr_debug("kobject: '%s' (%p): %s\n",
850                  kobject_name(kobj), kobj, __func__);
851         kfree(kset);
852 }
853 
854 static struct kobj_type kset_ktype = {
855         .sysfs_ops      = &kobj_sysfs_ops,
856         .release = kset_release,
857 };
858 
859 /**
860  * kset_create - create a struct kset dynamically
861  *
862  * @name: the name for the kset
863  * @uevent_ops: a struct kset_uevent_ops for the kset
864  * @parent_kobj: the parent kobject of this kset, if any.
865  *
866  * This function creates a kset structure dynamically.  This structure can
867  * then be registered with the system and show up in sysfs with a call to
868  * kset_register().  When you are finished with this structure, if
869  * kset_register() has been called, call kset_unregister() and the
870  * structure will be dynamically freed when it is no longer being used.
871  *
872  * If the kset was not able to be created, NULL will be returned.
873  */
874 static struct kset *kset_create(const char *name,
875                                 const struct kset_uevent_ops *uevent_ops,
876                                 struct kobject *parent_kobj)
877 {
878         struct kset *kset;
879         int retval;
880 
881         kset = kzalloc(sizeof(*kset), GFP_KERNEL);
882         if (!kset)
883                 return NULL;
884         retval = kobject_set_name(&kset->kobj, "%s", name);
885         if (retval) {
886                 kfree(kset);
887                 return NULL;
888         }
889         kset->uevent_ops = uevent_ops;
890         kset->kobj.parent = parent_kobj;
891 
892         /*
893          * The kobject of this kset will have a type of kset_ktype and belong to
894          * no kset itself.  That way we can properly free it when it is
895          * finished being used.
896          */
897         kset->kobj.ktype = &kset_ktype;
898         kset->kobj.kset = NULL;
899 
900         return kset;
901 }
902 
903 /**
904  * kset_create_and_add - create a struct kset dynamically and add it to sysfs
905  *
906  * @name: the name for the kset
907  * @uevent_ops: a struct kset_uevent_ops for the kset
908  * @parent_kobj: the parent kobject of this kset, if any.
909  *
910  * This function creates a kset structure dynamically and registers it
911  * with sysfs.  When you are finished with this structure, call
912  * kset_unregister() and the structure will be dynamically freed when it
913  * is no longer being used.
914  *
915  * If the kset was not able to be created, NULL will be returned.
916  */
917 struct kset *kset_create_and_add(const char *name,
918                                  const struct kset_uevent_ops *uevent_ops,
919                                  struct kobject *parent_kobj)
920 {
921         struct kset *kset;
922         int error;
923 
924         kset = kset_create(name, uevent_ops, parent_kobj);
925         if (!kset)
926                 return NULL;
927         error = kset_register(kset);
928         if (error) {
929                 kfree(kset);
930                 return NULL;
931         }
932         return kset;
933 }
934 EXPORT_SYMBOL_GPL(kset_create_and_add);
935 
936 
937 static DEFINE_SPINLOCK(kobj_ns_type_lock);
938 static const struct kobj_ns_type_operations *kobj_ns_ops_tbl[KOBJ_NS_TYPES];
939 
940 int kobj_ns_type_register(const struct kobj_ns_type_operations *ops)
941 {
942         enum kobj_ns_type type = ops->type;
943         int error;
944 
945         spin_lock(&kobj_ns_type_lock);
946 
947         error = -EINVAL;
948         if (type >= KOBJ_NS_TYPES)
949                 goto out;
950 
951         error = -EINVAL;
952         if (type <= KOBJ_NS_TYPE_NONE)
953                 goto out;
954 
955         error = -EBUSY;
956         if (kobj_ns_ops_tbl[type])
957                 goto out;
958 
959         error = 0;
960         kobj_ns_ops_tbl[type] = ops;
961 
962 out:
963         spin_unlock(&kobj_ns_type_lock);
964         return error;
965 }
966 
967 int kobj_ns_type_registered(enum kobj_ns_type type)
968 {
969         int registered = 0;
970 
971         spin_lock(&kobj_ns_type_lock);
972         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES))
973                 registered = kobj_ns_ops_tbl[type] != NULL;
974         spin_unlock(&kobj_ns_type_lock);
975 
976         return registered;
977 }
978 
979 const struct kobj_ns_type_operations *kobj_child_ns_ops(struct kobject *parent)
980 {
981         const struct kobj_ns_type_operations *ops = NULL;
982 
983         if (parent && parent->ktype && parent->ktype->child_ns_type)
984                 ops = parent->ktype->child_ns_type(parent);
985 
986         return ops;
987 }
988 
989 const struct kobj_ns_type_operations *kobj_ns_ops(struct kobject *kobj)
990 {
991         return kobj_child_ns_ops(kobj->parent);
992 }
993 
994 bool kobj_ns_current_may_mount(enum kobj_ns_type type)
995 {
996         bool may_mount = true;
997 
998         spin_lock(&kobj_ns_type_lock);
999         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1000             kobj_ns_ops_tbl[type])
1001                 may_mount = kobj_ns_ops_tbl[type]->current_may_mount();
1002         spin_unlock(&kobj_ns_type_lock);
1003 
1004         return may_mount;
1005 }
1006 
1007 void *kobj_ns_grab_current(enum kobj_ns_type type)
1008 {
1009         void *ns = NULL;
1010 
1011         spin_lock(&kobj_ns_type_lock);
1012         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1013             kobj_ns_ops_tbl[type])
1014                 ns = kobj_ns_ops_tbl[type]->grab_current_ns();
1015         spin_unlock(&kobj_ns_type_lock);
1016 
1017         return ns;
1018 }
1019 
1020 const void *kobj_ns_netlink(enum kobj_ns_type type, struct sock *sk)
1021 {
1022         const void *ns = NULL;
1023 
1024         spin_lock(&kobj_ns_type_lock);
1025         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1026             kobj_ns_ops_tbl[type])
1027                 ns = kobj_ns_ops_tbl[type]->netlink_ns(sk);
1028         spin_unlock(&kobj_ns_type_lock);
1029 
1030         return ns;
1031 }
1032 
1033 const void *kobj_ns_initial(enum kobj_ns_type type)
1034 {
1035         const void *ns = NULL;
1036 
1037         spin_lock(&kobj_ns_type_lock);
1038         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1039             kobj_ns_ops_tbl[type])
1040                 ns = kobj_ns_ops_tbl[type]->initial_ns();
1041         spin_unlock(&kobj_ns_type_lock);
1042 
1043         return ns;
1044 }
1045 
1046 void kobj_ns_drop(enum kobj_ns_type type, void *ns)
1047 {
1048         spin_lock(&kobj_ns_type_lock);
1049         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1050             kobj_ns_ops_tbl[type] && kobj_ns_ops_tbl[type]->drop_ns)
1051                 kobj_ns_ops_tbl[type]->drop_ns(ns);
1052         spin_unlock(&kobj_ns_type_lock);
1053 }
1054 
1055 EXPORT_SYMBOL(kobject_get);
1056 EXPORT_SYMBOL(kobject_put);
1057 EXPORT_SYMBOL(kobject_del);
1058 
1059 EXPORT_SYMBOL(kset_register);
1060 EXPORT_SYMBOL(kset_unregister);
1061 

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