lib/kobject.c

   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                 memcpy(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                         pr_err("%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                         pr_err("%s failed for %s (error: %d parent: %s)\n",
 241                                __func__, kobject_name(kobj), error,
 242                                parent ? kobject_name(parent) : "'none'");
 243         } else
 244                 kobj->state_in_sysfs = 1;
 245
 246         return error;
 247 }
 248
 249 /**
 250  * kobject_set_name_vargs - Set the name of an kobject
 251  * @kobj: struct kobject to set the name of
 252  * @fmt: format string used to build the name
 253  * @vargs: vargs to format the string.
 254  */
 255 int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
 256                                   va_list vargs)
 257 {
 258         const char *s;
 259
 260         if (kobj->name && !fmt)
 261                 return 0;
 262
 263         s = kvasprintf_const(GFP_KERNEL, fmt, vargs);
 264         if (!s)
 265                 return -ENOMEM;
 266
 267         /*
 268          * ewww... some of these buggers have '/' in the name ... If
 269          * that's the case, we need to make sure we have an actual
 270          * allocated copy to modify, since kvasprintf_const may have
 271          * returned something from .rodata.
 272          */
 273         if (strchr(s, '/')) {
 274                 char *t;
 275
 276                 t = kstrdup(s, GFP_KERNEL);
 277                 kfree_const(s);
 278                 if (!t)
 279                         return -ENOMEM;
 280                 strreplace(t, '/', '!');
 281                 s = t;
 282         }
 283         kfree_const(kobj->name);
 284         kobj->name = s;
 285
 286         return 0;
 287 }
 288
 289 /**
 290  * kobject_set_name - Set the name of a kobject
 291  * @kobj: struct kobject to set the name of
 292  * @fmt: format string used to build the name
 293  *
 294  * This sets the name of the kobject.  If you have already added the
 295  * kobject to the system, you must call kobject_rename() in order to
 296  * change the name of the kobject.
 297  */
 298 int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
 299 {
 300         va_list vargs;
 301         int retval;
 302
 303         va_start(vargs, fmt);
 304         retval = kobject_set_name_vargs(kobj, fmt, vargs);
 305         va_end(vargs);
 306
 307         return retval;
 308 }
 309 EXPORT_SYMBOL(kobject_set_name);
 310
 311 /**
 312  * kobject_init - initialize a kobject structure
 313  * @kobj: pointer to the kobject to initialize
 314  * @ktype: pointer to the ktype for this kobject.
 315  *
 316  * This function will properly initialize a kobject such that it can then
 317  * be passed to the kobject_add() call.
 318  *
 319  * After this function is called, the kobject MUST be cleaned up by a call
 320  * to kobject_put(), not by a call to kfree directly to ensure that all of
 321  * the memory is cleaned up properly.
 322  */
 323 void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
 324 {
 325         char *err_str;
 326
 327         if (!kobj) {
 328                 err_str = "invalid kobject pointer!";
 329                 goto error;
 330         }
 331         if (!ktype) {
 332                 err_str = "must have a ktype to be initialized properly!\n";
 333                 goto error;
 334         }
 335         if (kobj->state_initialized) {
 336                 /* do not error out as sometimes we can recover */
 337                 printk(KERN_ERR "kobject (%p): tried to init an initialized "
 338                        "object, something is seriously wrong.\n", kobj);
 339                 dump_stack();
 340         }
 341
 342         kobject_init_internal(kobj);
 343         kobj->ktype = ktype;
 344         return;
 345
 346 error:
 347         printk(KERN_ERR "kobject (%p): %s\n", kobj, err_str);
 348         dump_stack();
 349 }
 350 EXPORT_SYMBOL(kobject_init);
 351
 352 static __printf(3, 0) int kobject_add_varg(struct kobject *kobj,
 353                                            struct kobject *parent,
 354                                            const char *fmt, va_list vargs)
 355 {
 356         int retval;
 357
 358         retval = kobject_set_name_vargs(kobj, fmt, vargs);
 359         if (retval) {
 360                 printk(KERN_ERR "kobject: can not set name properly!\n");
 361                 return retval;
 362         }
 363         kobj->parent = parent;
 364         return kobject_add_internal(kobj);
 365 }
 366
 367 /**
 368  * kobject_add - the main kobject add function
 369  * @kobj: the kobject to add
 370  * @parent: pointer to the parent of the kobject.
 371  * @fmt: format to name the kobject with.
 372  *
 373  * The kobject name is set and added to the kobject hierarchy in this
 374  * function.
 375  *
 376  * If @parent is set, then the parent of the @kobj will be set to it.
 377  * If @parent is NULL, then the parent of the @kobj will be set to the
 378  * kobject associated with the kset assigned to this kobject.  If no kset
 379  * is assigned to the kobject, then the kobject will be located in the
 380  * root of the sysfs tree.
 381  *
 382  * If this function returns an error, kobject_put() must be called to
 383  * properly clean up the memory associated with the object.
 384  * Under no instance should the kobject that is passed to this function
 385  * be directly freed with a call to kfree(), that can leak memory.
 386  *
 387  * Note, no "add" uevent will be created with this call, the caller should set
 388  * up all of the necessary sysfs files for the object and then call
 389  * kobject_uevent() with the UEVENT_ADD parameter to ensure that
 390  * userspace is properly notified of this kobject's creation.
 391  */
 392 int kobject_add(struct kobject *kobj, struct kobject *parent,
 393                 const char *fmt, ...)
 394 {
 395         va_list args;
 396         int retval;
 397
 398         if (!kobj)
 399                 return -EINVAL;
 400
 401         if (!kobj->state_initialized) {
 402                 printk(KERN_ERR "kobject '%s' (%p): tried to add an "
 403                        "uninitialized object, something is seriously wrong.\n",
 404                        kobject_name(kobj), kobj);
 405                 dump_stack();
 406                 return -EINVAL;
 407         }
 408         va_start(args, fmt);
 409         retval = kobject_add_varg(kobj, parent, fmt, args);
 410         va_end(args);
 411
 412         return retval;
 413 }
 414 EXPORT_SYMBOL(kobject_add);
 415
 416 /**
 417  * kobject_init_and_add - initialize a kobject structure and add it to the kobject hierarchy
 418  * @kobj: pointer to the kobject to initialize
 419  * @ktype: pointer to the ktype for this kobject.
 420  * @parent: pointer to the parent of this kobject.
 421  * @fmt: the name of the kobject.
 422  *
 423  * This function combines the call to kobject_init() and
 424  * kobject_add().  The same type of error handling after a call to
 425  * kobject_add() and kobject lifetime rules are the same here.
 426  */
 427 int kobject_init_and_add(struct kobject *kobj, struct kobj_type *ktype,
 428                          struct kobject *parent, const char *fmt, ...)
 429 {
 430         va_list args;
 431         int retval;
 432
 433         kobject_init(kobj, ktype);
 434
 435         va_start(args, fmt);
 436         retval = kobject_add_varg(kobj, parent, fmt, args);
 437         va_end(args);
 438
 439         return retval;
 440 }
 441 EXPORT_SYMBOL_GPL(kobject_init_and_add);
 442
 443 /**
 444  * kobject_rename - change the name of an object
 445  * @kobj: object in question.
 446  * @new_name: object's new name
 447  *
 448  * It is the responsibility of the caller to provide mutual
 449  * exclusion between two different calls of kobject_rename
 450  * on the same kobject and to ensure that new_name is valid and
 451  * won't conflict with other kobjects.
 452  */
 453 int kobject_rename(struct kobject *kobj, const char *new_name)
 454 {
 455         int error = 0;
 456         const char *devpath = NULL;
 457         const char *dup_name = NULL, *name;
 458         char *devpath_string = NULL;
 459         char *envp[2];
 460
 461         kobj = kobject_get(kobj);
 462         if (!kobj)
 463                 return -EINVAL;
 464         if (!kobj->parent)
 465                 return -EINVAL;
 466
 467         devpath = kobject_get_path(kobj, GFP_KERNEL);
 468         if (!devpath) {
 469                 error = -ENOMEM;
 470                 goto out;
 471         }
 472         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 473         if (!devpath_string) {
 474                 error = -ENOMEM;
 475                 goto out;
 476         }
 477         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 478         envp[0] = devpath_string;
 479         envp[1] = NULL;
 480
 481         name = dup_name = kstrdup_const(new_name, GFP_KERNEL);
 482         if (!name) {
 483                 error = -ENOMEM;
 484                 goto out;
 485         }
 486
 487         error = sysfs_rename_dir_ns(kobj, new_name, kobject_namespace(kobj));
 488         if (error)
 489                 goto out;
 490
 491         /* Install the new kobject name */
 492         dup_name = kobj->name;
 493         kobj->name = name;
 494
 495         /* This function is mostly/only used for network interface.
 496          * Some hotplug package track interfaces by their name and
 497          * therefore want to know when the name is changed by the user. */
 498         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 499
 500 out:
 501         kfree_const(dup_name);
 502         kfree(devpath_string);
 503         kfree(devpath);
 504         kobject_put(kobj);
 505
 506         return error;
 507 }
 508 EXPORT_SYMBOL_GPL(kobject_rename);
 509
 510 /**
 511  * kobject_move - move object to another parent
 512  * @kobj: object in question.
 513  * @new_parent: object's new parent (can be NULL)
 514  */
 515 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 516 {
 517         int error;
 518         struct kobject *old_parent;
 519         const char *devpath = NULL;
 520         char *devpath_string = NULL;
 521         char *envp[2];
 522
 523         kobj = kobject_get(kobj);
 524         if (!kobj)
 525                 return -EINVAL;
 526         new_parent = kobject_get(new_parent);
 527         if (!new_parent) {
 528                 if (kobj->kset)
 529                         new_parent = kobject_get(&kobj->kset->kobj);
 530         }
 531
 532         /* old object path */
 533         devpath = kobject_get_path(kobj, GFP_KERNEL);
 534         if (!devpath) {
 535                 error = -ENOMEM;
 536                 goto out;
 537         }
 538         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 539         if (!devpath_string) {
 540                 error = -ENOMEM;
 541                 goto out;
 542         }
 543         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 544         envp[0] = devpath_string;
 545         envp[1] = NULL;
 546         error = sysfs_move_dir_ns(kobj, new_parent, kobject_namespace(kobj));
 547         if (error)
 548                 goto out;
 549         old_parent = kobj->parent;
 550         kobj->parent = new_parent;
 551         new_parent = NULL;
 552         kobject_put(old_parent);
 553         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 554 out:
 555         kobject_put(new_parent);
 556         kobject_put(kobj);
 557         kfree(devpath_string);
 558         kfree(devpath);
 559         return error;
 560 }
 561 EXPORT_SYMBOL_GPL(kobject_move);
 562
 563 /**
 564  * kobject_del - unlink kobject from hierarchy.
 565  * @kobj: object.
 566  */
 567 void kobject_del(struct kobject *kobj)
 568 {
 569         struct kernfs_node *sd;
 570
 571         if (!kobj)
 572                 return;
 573
 574         sd = kobj->sd;
 575         sysfs_remove_dir(kobj);
 576         sysfs_put(sd);
 577
 578         kobj->state_in_sysfs = 0;
 579         kobj_kset_leave(kobj);
 580         kobject_put(kobj->parent);
 581         kobj->parent = NULL;
 582 }
 583 EXPORT_SYMBOL(kobject_del);
 584
 585 /**
 586  * kobject_get - increment refcount for object.
 587  * @kobj: object.
 588  */
 589 struct kobject *kobject_get(struct kobject *kobj)
 590 {
 591         if (kobj) {
 592                 if (!kobj->state_initialized)
 593                         WARN(1, KERN_WARNING "kobject: '%s' (%p): is not "
 594                                "initialized, yet kobject_get() is being "
 595                                "called.\n", kobject_name(kobj), kobj);
 596                 kref_get(&kobj->kref);
 597         }
 598         return kobj;
 599 }
 600 EXPORT_SYMBOL(kobject_get);
 601
 602 static struct kobject * __must_check kobject_get_unless_zero(struct kobject *kobj)
 603 {
 604         if (!kref_get_unless_zero(&kobj->kref))
 605                 kobj = NULL;
 606         return kobj;
 607 }
 608
 609 /*
 610  * kobject_cleanup - free kobject resources.
 611  * @kobj: object to cleanup
 612  */
 613 static void kobject_cleanup(struct kobject *kobj)
 614 {
 615         struct kobj_type *t = get_ktype(kobj);
 616         const char *name = kobj->name;
 617
 618         pr_debug("kobject: '%s' (%p): %s, parent %p\n",
 619                  kobject_name(kobj), kobj, __func__, kobj->parent);
 620
 621         if (t && !t->release)
 622                 pr_debug("kobject: '%s' (%p): does not have a release() "
 623                          "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 "kobject: '%s' (%p): is not "
 687                                "initialized, yet kobject_put() is being "
 688                                "called.\n", 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                 printk(KERN_WARNING "%s: kobject_add error: %d\n",
 753                        __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
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 }