lib/kobject.c

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