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                         WARN(1,
 237                              "%s failed for %s with -EEXIST, don't try to register things with the same name in the same directory.\n",
 238                              __func__, kobject_name(kobj));
 239                 else
 240                         WARN(1, "%s failed for %s (error: %d parent: %s)\n",
 241                              __func__, kobject_name(kobj), error,
 242                              parent ? kobject_name(parent) : "'none'");
 243         } else
 244                 kobj->state_in_sysfs = 1;
 245
 246         return error;
 247 }
 248
 249 /**
 250  * kobject_set_name_vargs - Set the name of an kobject
 251  * @kobj: struct kobject to set the name of
 252  * @fmt: format string used to build the name
 253  * @vargs: vargs to format the string.
 254  */
 255 int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
 256                                   va_list vargs)
 257 {
 258         const char *s;
 259
 260         if (kobj->name && !fmt)
 261                 return 0;
 262
 263         s = kvasprintf_const(GFP_KERNEL, fmt, vargs);
 264         if (!s)
 265                 return -ENOMEM;
 266
 267         /*
 268          * ewww... some of these buggers have '/' in the name ... If
 269          * that's the case, we need to make sure we have an actual
 270          * allocated copy to modify, since kvasprintf_const may have
 271          * returned something from .rodata.
 272          */
 273         if (strchr(s, '/')) {
 274                 char *t;
 275
 276                 t = kstrdup(s, GFP_KERNEL);
 277                 kfree_const(s);
 278                 if (!t)
 279                         return -ENOMEM;
 280                 strreplace(t, '/', '!');
 281                 s = t;
 282         }
 283         kfree_const(kobj->name);
 284         kobj->name = s;
 285
 286         return 0;
 287 }
 288
 289 /**
 290  * kobject_set_name - Set the name of a kobject
 291  * @kobj: struct kobject to set the name of
 292  * @fmt: format string used to build the name
 293  *
 294  * This sets the name of the kobject.  If you have already added the
 295  * kobject to the system, you must call kobject_rename() in order to
 296  * change the name of the kobject.
 297  */
 298 int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
 299 {
 300         va_list vargs;
 301         int retval;
 302
 303         va_start(vargs, fmt);
 304         retval = kobject_set_name_vargs(kobj, fmt, vargs);
 305         va_end(vargs);
 306
 307         return retval;
 308 }
 309 EXPORT_SYMBOL(kobject_set_name);
 310
 311 /**
 312  * kobject_init - initialize a kobject structure
 313  * @kobj: pointer to the kobject to initialize
 314  * @ktype: pointer to the ktype for this kobject.
 315  *
 316  * This function will properly initialize a kobject such that it can then
 317  * be passed to the kobject_add() call.
 318  *
 319  * After this function is called, the kobject MUST be cleaned up by a call
 320  * to kobject_put(), not by a call to kfree directly to ensure that all of
 321  * the memory is cleaned up properly.
 322  */
 323 void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
 324 {
 325         char *err_str;
 326
 327         if (!kobj) {
 328                 err_str = "invalid kobject pointer!";
 329                 goto error;
 330         }
 331         if (!ktype) {
 332                 err_str = "must have a ktype to be initialized properly!\n";
 333                 goto error;
 334         }
 335         if (kobj->state_initialized) {
 336                 /* do not error out as sometimes we can recover */
 337                 pr_err("kobject (%p): tried to init an initialized object, something is seriously wrong.\n",
 338                        kobj);
 339                 dump_stack();
 340         }
 341
 342         kobject_init_internal(kobj);
 343         kobj->ktype = ktype;
 344         return;
 345
 346 error:
 347         pr_err("kobject (%p): %s\n", kobj, err_str);
 348         dump_stack();
 349 }
 350 EXPORT_SYMBOL(kobject_init);
 351
 352 static __printf(3, 0) int kobject_add_varg(struct kobject *kobj,
 353                                            struct kobject *parent,
 354                                            const char *fmt, va_list vargs)
 355 {
 356         int retval;
 357
 358         retval = kobject_set_name_vargs(kobj, fmt, vargs);
 359         if (retval) {
 360                 pr_err("kobject: can not set name properly!\n");
 361                 return retval;
 362         }
 363         kobj->parent = parent;
 364         return kobject_add_internal(kobj);
 365 }
 366
 367 /**
 368  * kobject_add - the main kobject add function
 369  * @kobj: the kobject to add
 370  * @parent: pointer to the parent of the kobject.
 371  * @fmt: format to name the kobject with.
 372  *
 373  * The kobject name is set and added to the kobject hierarchy in this
 374  * function.
 375  *
 376  * If @parent is set, then the parent of the @kobj will be set to it.
 377  * If @parent is NULL, then the parent of the @kobj will be set to the
 378  * kobject associated with the kset assigned to this kobject.  If no kset
 379  * is assigned to the kobject, then the kobject will be located in the
 380  * root of the sysfs tree.
 381  *
 382  * If this function returns an error, kobject_put() must be called to
 383  * properly clean up the memory associated with the object.
 384  * Under no instance should the kobject that is passed to this function
 385  * be directly freed with a call to kfree(), that can leak memory.
 386  *
 387  * Note, no "add" uevent will be created with this call, the caller should set
 388  * up all of the necessary sysfs files for the object and then call
 389  * kobject_uevent() with the UEVENT_ADD parameter to ensure that
 390  * userspace is properly notified of this kobject's creation.
 391  */
 392 int kobject_add(struct kobject *kobj, struct kobject *parent,
 393                 const char *fmt, ...)
 394 {
 395         va_list args;
 396         int retval;
 397
 398         if (!kobj)
 399                 return -EINVAL;
 400
 401         if (!kobj->state_initialized) {
 402                 pr_err("kobject '%s' (%p): tried to add an uninitialized object, something is seriously wrong.\n",
 403                        kobject_name(kobj), kobj);
 404                 dump_stack();
 405                 return -EINVAL;
 406         }
 407         va_start(args, fmt);
 408         retval = kobject_add_varg(kobj, parent, fmt, args);
 409         va_end(args);
 410
 411         return retval;
 412 }
 413 EXPORT_SYMBOL(kobject_add);
 414
 415 /**
 416  * kobject_init_and_add - initialize a kobject structure and add it to the kobject hierarchy
 417  * @kobj: pointer to the kobject to initialize
 418  * @ktype: pointer to the ktype for this kobject.
 419  * @parent: pointer to the parent of this kobject.
 420  * @fmt: the name of the kobject.
 421  *
 422  * This function combines the call to kobject_init() and
 423  * kobject_add().  The same type of error handling after a call to
 424  * kobject_add() and kobject lifetime rules are the same here.
 425  */
 426 int kobject_init_and_add(struct kobject *kobj, struct kobj_type *ktype,
 427                          struct kobject *parent, const char *fmt, ...)
 428 {
 429         va_list args;
 430         int retval;
 431
 432         kobject_init(kobj, ktype);
 433
 434         va_start(args, fmt);
 435         retval = kobject_add_varg(kobj, parent, fmt, args);
 436         va_end(args);
 437
 438         return retval;
 439 }
 440 EXPORT_SYMBOL_GPL(kobject_init_and_add);
 441
 442 /**
 443  * kobject_rename - change the name of an object
 444  * @kobj: object in question.
 445  * @new_name: object's new name
 446  *
 447  * It is the responsibility of the caller to provide mutual
 448  * exclusion between two different calls of kobject_rename
 449  * on the same kobject and to ensure that new_name is valid and
 450  * won't conflict with other kobjects.
 451  */
 452 int kobject_rename(struct kobject *kobj, const char *new_name)
 453 {
 454         int error = 0;
 455         const char *devpath = NULL;
 456         const char *dup_name = NULL, *name;
 457         char *devpath_string = NULL;
 458         char *envp[2];
 459
 460         kobj = kobject_get(kobj);
 461         if (!kobj)
 462                 return -EINVAL;
 463         if (!kobj->parent)
 464                 return -EINVAL;
 465
 466         devpath = kobject_get_path(kobj, GFP_KERNEL);
 467         if (!devpath) {
 468                 error = -ENOMEM;
 469                 goto out;
 470         }
 471         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 472         if (!devpath_string) {
 473                 error = -ENOMEM;
 474                 goto out;
 475         }
 476         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 477         envp[0] = devpath_string;
 478         envp[1] = NULL;
 479
 480         name = dup_name = kstrdup_const(new_name, GFP_KERNEL);
 481         if (!name) {
 482                 error = -ENOMEM;
 483                 goto out;
 484         }
 485
 486         error = sysfs_rename_dir_ns(kobj, new_name, kobject_namespace(kobj));
 487         if (error)
 488                 goto out;
 489
 490         /* Install the new kobject name */
 491         dup_name = kobj->name;
 492         kobj->name = name;
 493
 494         /* This function is mostly/only used for network interface.
 495          * Some hotplug package track interfaces by their name and
 496          * therefore want to know when the name is changed by the user. */
 497         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 498
 499 out:
 500         kfree_const(dup_name);
 501         kfree(devpath_string);
 502         kfree(devpath);
 503         kobject_put(kobj);
 504
 505         return error;
 506 }
 507 EXPORT_SYMBOL_GPL(kobject_rename);
 508
 509 /**
 510  * kobject_move - move object to another parent
 511  * @kobj: object in question.
 512  * @new_parent: object's new parent (can be NULL)
 513  */
 514 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 515 {
 516         int error;
 517         struct kobject *old_parent;
 518         const char *devpath = NULL;
 519         char *devpath_string = NULL;
 520         char *envp[2];
 521
 522         kobj = kobject_get(kobj);
 523         if (!kobj)
 524                 return -EINVAL;
 525         new_parent = kobject_get(new_parent);
 526         if (!new_parent) {
 527                 if (kobj->kset)
 528                         new_parent = kobject_get(&kobj->kset->kobj);
 529         }
 530
 531         /* old object path */
 532         devpath = kobject_get_path(kobj, GFP_KERNEL);
 533         if (!devpath) {
 534                 error = -ENOMEM;
 535                 goto out;
 536         }
 537         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 538         if (!devpath_string) {
 539                 error = -ENOMEM;
 540                 goto out;
 541         }
 542         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 543         envp[0] = devpath_string;
 544         envp[1] = NULL;
 545         error = sysfs_move_dir_ns(kobj, new_parent, kobject_namespace(kobj));
 546         if (error)
 547                 goto out;
 548         old_parent = kobj->parent;
 549         kobj->parent = new_parent;
 550         new_parent = NULL;
 551         kobject_put(old_parent);
 552         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 553 out:
 554         kobject_put(new_parent);
 555         kobject_put(kobj);
 556         kfree(devpath_string);
 557         kfree(devpath);
 558         return error;
 559 }
 560 EXPORT_SYMBOL_GPL(kobject_move);
 561
 562 /**
 563  * kobject_del - unlink kobject from hierarchy.
 564  * @kobj: object.
 565  */
 566 void kobject_del(struct kobject *kobj)
 567 {
 568         struct kernfs_node *sd;
 569
 570         if (!kobj)
 571                 return;
 572
 573         sd = kobj->sd;
 574         sysfs_remove_dir(kobj);
 575         sysfs_put(sd);
 576
 577         kobj->state_in_sysfs = 0;
 578         kobj_kset_leave(kobj);
 579         kobject_put(kobj->parent);
 580         kobj->parent = NULL;
 581 }
 582 EXPORT_SYMBOL(kobject_del);
 583
 584 /**
 585  * kobject_get - increment refcount for object.
 586  * @kobj: object.
 587  */
 588 struct kobject *kobject_get(struct kobject *kobj)
 589 {
 590         if (kobj) {
 591                 if (!kobj->state_initialized)
 592                         WARN(1, KERN_WARNING
 593                                 "kobject: '%s' (%p): is not initialized, yet kobject_get() is being called.\n",
 594                              kobject_name(kobj), kobj);
 595                 kref_get(&kobj->kref);
 596         }
 597         return kobj;
 598 }
 599 EXPORT_SYMBOL(kobject_get);
 600
 601 struct kobject * __must_check kobject_get_unless_zero(struct kobject *kobj)
 602 {
 603         if (!kobj)
 604                 return NULL;
 605         if (!kref_get_unless_zero(&kobj->kref))
 606                 kobj = NULL;
 607         return kobj;
 608 }
 609 EXPORT_SYMBOL(kobject_get_unless_zero);
 610
 611 /*
 612  * kobject_cleanup - free kobject resources.
 613  * @kobj: object to cleanup
 614  */
 615 static void kobject_cleanup(struct kobject *kobj)
 616 {
 617         struct kobj_type *t = get_ktype(kobj);
 618         const char *name = kobj->name;
 619
 620         pr_debug("kobject: '%s' (%p): %s, parent %p\n",
 621                  kobject_name(kobj), kobj, __func__, kobj->parent);
 622
 623         if (t && !t->release)
 624                 pr_debug("kobject: '%s' (%p): does not have a release() function, it is broken and must be fixed.\n",
 625                          kobject_name(kobj), kobj);
 626
 627         /* send "remove" if the caller did not do it but sent "add" */
 628         if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
 629                 pr_debug("kobject: '%s' (%p): auto cleanup 'remove' event\n",
 630                          kobject_name(kobj), kobj);
 631                 kobject_uevent(kobj, KOBJ_REMOVE);
 632         }
 633
 634         /* remove from sysfs if the caller did not do it */
 635         if (kobj->state_in_sysfs) {
 636                 pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n",
 637                          kobject_name(kobj), kobj);
 638                 kobject_del(kobj);
 639         }
 640
 641         if (t && t->release) {
 642                 pr_debug("kobject: '%s' (%p): calling ktype release\n",
 643                          kobject_name(kobj), kobj);
 644                 t->release(kobj);
 645         }
 646
 647         /* free name if we allocated it */
 648         if (name) {
 649                 pr_debug("kobject: '%s': free name\n", name);
 650                 kfree_const(name);
 651         }
 652 }
 653
 654 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
 655 static void kobject_delayed_cleanup(struct work_struct *work)
 656 {
 657         kobject_cleanup(container_of(to_delayed_work(work),
 658                                      struct kobject, release));
 659 }
 660 #endif
 661
 662 static void kobject_release(struct kref *kref)
 663 {
 664         struct kobject *kobj = container_of(kref, struct kobject, kref);
 665 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
 666         unsigned long delay = HZ + HZ * (get_random_int() & 0x3);
 667         pr_info("kobject: '%s' (%p): %s, parent %p (delayed %ld)\n",
 668                  kobject_name(kobj), kobj, __func__, kobj->parent, delay);
 669         INIT_DELAYED_WORK(&kobj->release, kobject_delayed_cleanup);
 670
 671         schedule_delayed_work(&kobj->release, delay);
 672 #else
 673         kobject_cleanup(kobj);
 674 #endif
 675 }
 676
 677 /**
 678  * kobject_put - decrement refcount for object.
 679  * @kobj: object.
 680  *
 681  * Decrement the refcount, and if 0, call kobject_cleanup().
 682  */
 683 void kobject_put(struct kobject *kobj)
 684 {
 685         if (kobj) {
 686                 if (!kobj->state_initialized)
 687                         WARN(1, KERN_WARNING
 688                                 "kobject: '%s' (%p): is not initialized, yet kobject_put() is being called.\n",
 689                              kobject_name(kobj), kobj);
 690                 kref_put(&kobj->kref, kobject_release);
 691         }
 692 }
 693 EXPORT_SYMBOL(kobject_put);
 694
 695 static void dynamic_kobj_release(struct kobject *kobj)
 696 {
 697         pr_debug("kobject: (%p): %s\n", kobj, __func__);
 698         kfree(kobj);
 699 }
 700
 701 static struct kobj_type dynamic_kobj_ktype = {
 702         .release        = dynamic_kobj_release,
 703         .sysfs_ops      = &kobj_sysfs_ops,
 704 };
 705
 706 /**
 707  * kobject_create - create a struct kobject dynamically
 708  *
 709  * This function creates a kobject structure dynamically and sets it up
 710  * to be a "dynamic" kobject with a default release function set up.
 711  *
 712  * If the kobject was not able to be created, NULL will be returned.
 713  * The kobject structure returned from here must be cleaned up with a
 714  * call to kobject_put() and not kfree(), as kobject_init() has
 715  * already been called on this structure.
 716  */
 717 struct kobject *kobject_create(void)
 718 {
 719         struct kobject *kobj;
 720
 721         kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
 722         if (!kobj)
 723                 return NULL;
 724
 725         kobject_init(kobj, &dynamic_kobj_ktype);
 726         return kobj;
 727 }
 728
 729 /**
 730  * kobject_create_and_add - create a struct kobject dynamically and register it with sysfs
 731  *
 732  * @name: the name for the kobject
 733  * @parent: the parent kobject of this kobject, if any.
 734  *
 735  * This function creates a kobject structure dynamically and registers it
 736  * with sysfs.  When you are finished with this structure, call
 737  * kobject_put() and the structure will be dynamically freed when
 738  * it is no longer being used.
 739  *
 740  * If the kobject was not able to be created, NULL will be returned.
 741  */
 742 struct kobject *kobject_create_and_add(const char *name, struct kobject *parent)
 743 {
 744         struct kobject *kobj;
 745         int retval;
 746
 747         kobj = kobject_create();
 748         if (!kobj)
 749                 return NULL;
 750
 751         retval = kobject_add(kobj, parent, "%s", name);
 752         if (retval) {
 753                 pr_warn("%s: kobject_add error: %d\n", __func__, retval);
 754                 kobject_put(kobj);
 755                 kobj = NULL;
 756         }
 757         return kobj;
 758 }
 759 EXPORT_SYMBOL_GPL(kobject_create_and_add);
 760
 761 /**
 762  * kset_init - initialize a kset for use
 763  * @k: kset
 764  */
 765 void kset_init(struct kset *k)
 766 {
 767         kobject_init_internal(&k->kobj);
 768         INIT_LIST_HEAD(&k->list);
 769         spin_lock_init(&k->list_lock);
 770 }
 771
 772 /* default kobject attribute operations */
 773 static ssize_t kobj_attr_show(struct kobject *kobj, struct attribute *attr,
 774                               char *buf)
 775 {
 776         struct kobj_attribute *kattr;
 777         ssize_t ret = -EIO;
 778
 779         kattr = container_of(attr, struct kobj_attribute, attr);
 780         if (kattr->show)
 781                 ret = kattr->show(kobj, kattr, buf);
 782         return ret;
 783 }
 784
 785 static ssize_t kobj_attr_store(struct kobject *kobj, struct attribute *attr,
 786                                const char *buf, size_t count)
 787 {
 788         struct kobj_attribute *kattr;
 789         ssize_t ret = -EIO;
 790
 791         kattr = container_of(attr, struct kobj_attribute, attr);
 792         if (kattr->store)
 793                 ret = kattr->store(kobj, kattr, buf, count);
 794         return ret;
 795 }
 796
 797 const struct sysfs_ops kobj_sysfs_ops = {
 798         .show   = kobj_attr_show,
 799         .store  = kobj_attr_store,
 800 };
 801 EXPORT_SYMBOL_GPL(kobj_sysfs_ops);
 802
 803 /**
 804  * kset_register - initialize and add a kset.
 805  * @k: kset.
 806  */
 807 int kset_register(struct kset *k)
 808 {
 809         int err;
 810
 811         if (!k)
 812                 return -EINVAL;
 813
 814         kset_init(k);
 815         err = kobject_add_internal(&k->kobj);
 816         if (err)
 817                 return err;
 818         kobject_uevent(&k->kobj, KOBJ_ADD);
 819         return 0;
 820 }
 821 EXPORT_SYMBOL(kset_register);
 822
 823 /**
 824  * kset_unregister - remove a kset.
 825  * @k: kset.
 826  */
 827 void kset_unregister(struct kset *k)
 828 {
 829         if (!k)
 830                 return;
 831         kobject_del(&k->kobj);
 832         kobject_put(&k->kobj);
 833 }
 834 EXPORT_SYMBOL(kset_unregister);
 835
 836 /**
 837  * kset_find_obj - search for object in kset.
 838  * @kset: kset we're looking in.
 839  * @name: object's name.
 840  *
 841  * Lock kset via @kset->subsys, and iterate over @kset->list,
 842  * looking for a matching kobject. If matching object is found
 843  * take a reference and return the object.
 844  */
 845 struct kobject *kset_find_obj(struct kset *kset, const char *name)
 846 {
 847         struct kobject *k;
 848         struct kobject *ret = NULL;
 849
 850         spin_lock(&kset->list_lock);
 851
 852         list_for_each_entry(k, &kset->list, entry) {
 853                 if (kobject_name(k) && !strcmp(kobject_name(k), name)) {
 854                         ret = kobject_get_unless_zero(k);
 855                         break;
 856                 }
 857         }
 858
 859         spin_unlock(&kset->list_lock);
 860         return ret;
 861 }
 862 EXPORT_SYMBOL_GPL(kset_find_obj);
 863
 864 static void kset_release(struct kobject *kobj)
 865 {
 866         struct kset *kset = container_of(kobj, struct kset, kobj);
 867         pr_debug("kobject: '%s' (%p): %s\n",
 868                  kobject_name(kobj), kobj, __func__);
 869         kfree(kset);
 870 }
 871
 872 static struct kobj_type kset_ktype = {
 873         .sysfs_ops      = &kobj_sysfs_ops,
 874         .release = kset_release,
 875 };
 876
 877 /**
 878  * kset_create - create a struct kset dynamically
 879  *
 880  * @name: the name for the kset
 881  * @uevent_ops: a struct kset_uevent_ops for the kset
 882  * @parent_kobj: the parent kobject of this kset, if any.
 883  *
 884  * This function creates a kset structure dynamically.  This structure can
 885  * then be registered with the system and show up in sysfs with a call to
 886  * kset_register().  When you are finished with this structure, if
 887  * kset_register() has been called, call kset_unregister() and the
 888  * structure will be dynamically freed when it is no longer being used.
 889  *
 890  * If the kset was not able to be created, NULL will be returned.
 891  */
 892 static struct kset *kset_create(const char *name,
 893                                 const struct kset_uevent_ops *uevent_ops,
 894                                 struct kobject *parent_kobj)
 895 {
 896         struct kset *kset;
 897         int retval;
 898
 899         kset = kzalloc(sizeof(*kset), GFP_KERNEL);
 900         if (!kset)
 901                 return NULL;
 902         retval = kobject_set_name(&kset->kobj, "%s", name);
 903         if (retval) {
 904                 kfree(kset);
 905                 return NULL;
 906         }
 907         kset->uevent_ops = uevent_ops;
 908         kset->kobj.parent = parent_kobj;
 909
 910         /*
 911          * The kobject of this kset will have a type of kset_ktype and belong to
 912          * no kset itself.  That way we can properly free it when it is
 913          * finished being used.
 914          */
 915         kset->kobj.ktype = &kset_ktype;
 916         kset->kobj.kset = NULL;
 917
 918         return kset;
 919 }
 920
 921 /**
 922  * kset_create_and_add - create a struct kset dynamically and add it to sysfs
 923  *
 924  * @name: the name for the kset
 925  * @uevent_ops: a struct kset_uevent_ops for the kset
 926  * @parent_kobj: the parent kobject of this kset, if any.
 927  *
 928  * This function creates a kset structure dynamically and registers it
 929  * with sysfs.  When you are finished with this structure, call
 930  * kset_unregister() and the structure will be dynamically freed when it
 931  * is no longer being used.
 932  *
 933  * If the kset was not able to be created, NULL will be returned.
 934  */
 935 struct kset *kset_create_and_add(const char *name,
 936                                  const struct kset_uevent_ops *uevent_ops,
 937                                  struct kobject *parent_kobj)
 938 {
 939         struct kset *kset;
 940         int error;
 941
 942         kset = kset_create(name, uevent_ops, parent_kobj);
 943         if (!kset)
 944                 return NULL;
 945         error = kset_register(kset);
 946         if (error) {
 947                 kfree(kset);
 948                 return NULL;
 949         }
 950         return kset;
 951 }
 952 EXPORT_SYMBOL_GPL(kset_create_and_add);
 953
 954
 955 static DEFINE_SPINLOCK(kobj_ns_type_lock);
 956 static const struct kobj_ns_type_operations *kobj_ns_ops_tbl[KOBJ_NS_TYPES];
 957
 958 int kobj_ns_type_register(const struct kobj_ns_type_operations *ops)
 959 {
 960         enum kobj_ns_type type = ops->type;
 961         int error;
 962
 963         spin_lock(&kobj_ns_type_lock);
 964
 965         error = -EINVAL;
 966         if (type >= KOBJ_NS_TYPES)
 967                 goto out;
 968
 969         error = -EINVAL;
 970         if (type <= KOBJ_NS_TYPE_NONE)
 971                 goto out;
 972
 973         error = -EBUSY;
 974         if (kobj_ns_ops_tbl[type])
 975                 goto out;
 976
 977         error = 0;
 978         kobj_ns_ops_tbl[type] = ops;
 979
 980 out:
 981         spin_unlock(&kobj_ns_type_lock);
 982         return error;
 983 }
 984
 985 int kobj_ns_type_registered(enum kobj_ns_type type)
 986 {
 987         int registered = 0;
 988
 989         spin_lock(&kobj_ns_type_lock);
 990         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES))
 991                 registered = kobj_ns_ops_tbl[type] != NULL;
 992         spin_unlock(&kobj_ns_type_lock);
 993
 994         return registered;
 995 }
 996
 997 const struct kobj_ns_type_operations *kobj_child_ns_ops(struct kobject *parent)
 998 {
 999         const struct kobj_ns_type_operations *ops = NULL;
1000
1001         if (parent && parent->ktype && parent->ktype->child_ns_type)
1002                 ops = parent->ktype->child_ns_type(parent);
1003
1004         return ops;
1005 }
1006
1007 const struct kobj_ns_type_operations *kobj_ns_ops(struct kobject *kobj)
1008 {
1009         return kobj_child_ns_ops(kobj->parent);
1010 }
1011
1012 bool kobj_ns_current_may_mount(enum kobj_ns_type type)
1013 {
1014         bool may_mount = true;
1015
1016         spin_lock(&kobj_ns_type_lock);
1017         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1018             kobj_ns_ops_tbl[type])
1019                 may_mount = kobj_ns_ops_tbl[type]->current_may_mount();
1020         spin_unlock(&kobj_ns_type_lock);
1021
1022         return may_mount;
1023 }
1024
1025 void *kobj_ns_grab_current(enum kobj_ns_type type)
1026 {
1027         void *ns = NULL;
1028
1029         spin_lock(&kobj_ns_type_lock);
1030         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1031             kobj_ns_ops_tbl[type])
1032                 ns = kobj_ns_ops_tbl[type]->grab_current_ns();
1033         spin_unlock(&kobj_ns_type_lock);
1034
1035         return ns;
1036 }
1037 EXPORT_SYMBOL_GPL(kobj_ns_grab_current);
1038
1039 const void *kobj_ns_netlink(enum kobj_ns_type type, struct sock *sk)
1040 {
1041         const void *ns = NULL;
1042
1043         spin_lock(&kobj_ns_type_lock);
1044         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1045             kobj_ns_ops_tbl[type])
1046                 ns = kobj_ns_ops_tbl[type]->netlink_ns(sk);
1047         spin_unlock(&kobj_ns_type_lock);
1048
1049         return ns;
1050 }
1051
1052 const void *kobj_ns_initial(enum kobj_ns_type type)
1053 {
1054         const void *ns = NULL;
1055
1056         spin_lock(&kobj_ns_type_lock);
1057         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1058             kobj_ns_ops_tbl[type])
1059                 ns = kobj_ns_ops_tbl[type]->initial_ns();
1060         spin_unlock(&kobj_ns_type_lock);
1061
1062         return ns;
1063 }
1064
1065 void kobj_ns_drop(enum kobj_ns_type type, void *ns)
1066 {
1067         spin_lock(&kobj_ns_type_lock);
1068         if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
1069             kobj_ns_ops_tbl[type] && kobj_ns_ops_tbl[type]->drop_ns)
1070                 kobj_ns_ops_tbl[type]->drop_ns(ns);
1071         spin_unlock(&kobj_ns_type_lock);
1072 }
1073 EXPORT_SYMBOL_GPL(kobj_ns_drop);