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/module.h>
  18 #include <linux/stat.h>
  19 #include <linux/slab.h>
  20
  21 /*
  22  * populate_dir - populate directory with attributes.
  23  * @kobj: object we're working on.
  24  *
  25  * Most subsystems have a set of default attributes that are associated
  26  * with an object that registers with them.  This is a helper called during
  27  * object registration that loops through the default attributes of the
  28  * subsystem and creates attributes files for them in sysfs.
  29  */
  30 static int populate_dir(struct kobject *kobj)
  31 {
  32         struct kobj_type *t = get_ktype(kobj);
  33         struct attribute *attr;
  34         int error = 0;
  35         int i;
  36
  37         if (t && t->default_attrs) {
  38                 for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
  39                         error = sysfs_create_file(kobj, attr);
  40                         if (error)
  41                                 break;
  42                 }
  43         }
  44         return error;
  45 }
  46
  47 static int create_dir(struct kobject *kobj)
  48 {
  49         int error = 0;
  50         if (kobject_name(kobj)) {
  51                 error = sysfs_create_dir(kobj);
  52                 if (!error) {
  53                         error = populate_dir(kobj);
  54                         if (error)
  55                                 sysfs_remove_dir(kobj);
  56                 }
  57         }
  58         return error;
  59 }
  60
  61 static int get_kobj_path_length(struct kobject *kobj)
  62 {
  63         int length = 1;
  64         struct kobject *parent = kobj;
  65
  66         /* walk up the ancestors until we hit the one pointing to the
  67          * root.
  68          * Add 1 to strlen for leading '/' of each level.
  69          */
  70         do {
  71                 if (kobject_name(parent) == NULL)
  72                         return 0;
  73                 length += strlen(kobject_name(parent)) + 1;
  74                 parent = parent->parent;
  75         } while (parent);
  76         return length;
  77 }
  78
  79 static void fill_kobj_path(struct kobject *kobj, char *path, int length)
  80 {
  81         struct kobject *parent;
  82
  83         --length;
  84         for (parent = kobj; parent; parent = parent->parent) {
  85                 int cur = strlen(kobject_name(parent));
  86                 /* back up enough to print this name with '/' */
  87                 length -= cur;
  88                 strncpy(path + length, kobject_name(parent), cur);
  89                 *(path + --length) = '/';
  90         }
  91
  92         pr_debug("kobject: '%s' (%p): %s: path = '%s'\n", kobject_name(kobj),
  93                  kobj, __func__, path);
  94 }
  95
  96 /**
  97  * kobject_get_path - generate and return the path associated with a given kobj and kset pair.
  98  *
  99  * @kobj:       kobject in question, with which to build the path
 100  * @gfp_mask:   the allocation type used to allocate the path
 101  *
 102  * The result must be freed by the caller with kfree().
 103  */
 104 char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
 105 {
 106         char *path;
 107         int len;
 108
 109         len = get_kobj_path_length(kobj);
 110         if (len == 0)
 111                 return NULL;
 112         path = kzalloc(len, gfp_mask);
 113         if (!path)
 114                 return NULL;
 115         fill_kobj_path(kobj, path, len);
 116
 117         return path;
 118 }
 119 EXPORT_SYMBOL_GPL(kobject_get_path);
 120
 121 /* add the kobject to its kset's list */
 122 static void kobj_kset_join(struct kobject *kobj)
 123 {
 124         if (!kobj->kset)
 125                 return;
 126
 127         kset_get(kobj->kset);
 128         spin_lock(&kobj->kset->list_lock);
 129         list_add_tail(&kobj->entry, &kobj->kset->list);
 130         spin_unlock(&kobj->kset->list_lock);
 131 }
 132
 133 /* remove the kobject from its kset's list */
 134 static void kobj_kset_leave(struct kobject *kobj)
 135 {
 136         if (!kobj->kset)
 137                 return;
 138
 139         spin_lock(&kobj->kset->list_lock);
 140         list_del_init(&kobj->entry);
 141         spin_unlock(&kobj->kset->list_lock);
 142         kset_put(kobj->kset);
 143 }
 144
 145 static void kobject_init_internal(struct kobject *kobj)
 146 {
 147         if (!kobj)
 148                 return;
 149         kref_init(&kobj->kref);
 150         INIT_LIST_HEAD(&kobj->entry);
 151         kobj->state_in_sysfs = 0;
 152         kobj->state_add_uevent_sent = 0;
 153         kobj->state_remove_uevent_sent = 0;
 154         kobj->state_initialized = 1;
 155 }
 156
 157
 158 static int kobject_add_internal(struct kobject *kobj)
 159 {
 160         int error = 0;
 161         struct kobject *parent;
 162
 163         if (!kobj)
 164                 return -ENOENT;
 165
 166         if (!kobj->name || !kobj->name[0]) {
 167                 WARN(1, "kobject: (%p): attempted to be registered with empty "
 168                          "name!\n", kobj);
 169                 return -EINVAL;
 170         }
 171
 172         parent = kobject_get(kobj->parent);
 173
 174         /* join kset if set, use it as parent if we do not already have one */
 175         if (kobj->kset) {
 176                 if (!parent)
 177                         parent = kobject_get(&kobj->kset->kobj);
 178                 kobj_kset_join(kobj);
 179                 kobj->parent = parent;
 180         }
 181
 182         pr_debug("kobject: '%s' (%p): %s: parent: '%s', set: '%s'\n",
 183                  kobject_name(kobj), kobj, __func__,
 184                  parent ? kobject_name(parent) : "<NULL>",
 185                  kobj->kset ? kobject_name(&kobj->kset->kobj) : "<NULL>");
 186
 187         error = create_dir(kobj);
 188         if (error) {
 189                 kobj_kset_leave(kobj);
 190                 kobject_put(parent);
 191                 kobj->parent = NULL;
 192
 193                 /* be noisy on error issues */
 194                 if (error == -EEXIST)
 195                         printk(KERN_ERR "%s failed for %s with "
 196                                "-EEXIST, don't try to register things with "
 197                                "the same name in the same directory.\n",
 198                                __func__, kobject_name(kobj));
 199                 else
 200                         printk(KERN_ERR "%s failed for %s (%d)\n",
 201                                __func__, kobject_name(kobj), error);
 202                 dump_stack();
 203         } else
 204                 kobj->state_in_sysfs = 1;
 205
 206         return error;
 207 }
 208
 209 /**
 210  * kobject_set_name_vargs - Set the name of an kobject
 211  * @kobj: struct kobject to set the name of
 212  * @fmt: format string used to build the name
 213  * @vargs: vargs to format the string.
 214  */
 215 static int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
 216                                   va_list vargs)
 217 {
 218         const char *old_name = kobj->name;
 219         char *s;
 220
 221         kobj->name = kvasprintf(GFP_KERNEL, fmt, vargs);
 222         if (!kobj->name)
 223                 return -ENOMEM;
 224
 225         /* ewww... some of these buggers have '/' in the name ... */
 226         while ((s = strchr(kobj->name, '/')))
 227                 s[0] = '!';
 228
 229         kfree(old_name);
 230         return 0;
 231 }
 232
 233 /**
 234  * kobject_set_name - Set the name of a kobject
 235  * @kobj: struct kobject to set the name of
 236  * @fmt: format string used to build the name
 237  *
 238  * This sets the name of the kobject.  If you have already added the
 239  * kobject to the system, you must call kobject_rename() in order to
 240  * change the name of the kobject.
 241  */
 242 int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
 243 {
 244         va_list vargs;
 245         int retval;
 246
 247         va_start(vargs, fmt);
 248         retval = kobject_set_name_vargs(kobj, fmt, vargs);
 249         va_end(vargs);
 250
 251         return retval;
 252 }
 253 EXPORT_SYMBOL(kobject_set_name);
 254
 255 /**
 256  * kobject_init - initialize a kobject structure
 257  * @kobj: pointer to the kobject to initialize
 258  * @ktype: pointer to the ktype for this kobject.
 259  *
 260  * This function will properly initialize a kobject such that it can then
 261  * be passed to the kobject_add() call.
 262  *
 263  * After this function is called, the kobject MUST be cleaned up by a call
 264  * to kobject_put(), not by a call to kfree directly to ensure that all of
 265  * the memory is cleaned up properly.
 266  */
 267 void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
 268 {
 269         char *err_str;
 270
 271         if (!kobj) {
 272                 err_str = "invalid kobject pointer!";
 273                 goto error;
 274         }
 275         if (!ktype) {
 276                 err_str = "must have a ktype to be initialized properly!\n";
 277                 goto error;
 278         }
 279         if (kobj->state_initialized) {
 280                 /* do not error out as sometimes we can recover */
 281                 printk(KERN_ERR "kobject (%p): tried to init an initialized "
 282                        "object, something is seriously wrong.\n", kobj);
 283                 dump_stack();
 284         }
 285
 286         kobject_init_internal(kobj);
 287         kobj->ktype = ktype;
 288         return;
 289
 290 error:
 291         printk(KERN_ERR "kobject (%p): %s\n", kobj, err_str);
 292         dump_stack();
 293 }
 294 EXPORT_SYMBOL(kobject_init);
 295
 296 static int kobject_add_varg(struct kobject *kobj, struct kobject *parent,
 297                             const char *fmt, va_list vargs)
 298 {
 299         int retval;
 300
 301         retval = kobject_set_name_vargs(kobj, fmt, vargs);
 302         if (retval) {
 303                 printk(KERN_ERR "kobject: can not set name properly!\n");
 304                 return retval;
 305         }
 306         kobj->parent = parent;
 307         return kobject_add_internal(kobj);
 308 }
 309
 310 /**
 311  * kobject_add - the main kobject add function
 312  * @kobj: the kobject to add
 313  * @parent: pointer to the parent of the kobject.
 314  * @fmt: format to name the kobject with.
 315  *
 316  * The kobject name is set and added to the kobject hierarchy in this
 317  * function.
 318  *
 319  * If @parent is set, then the parent of the @kobj will be set to it.
 320  * If @parent is NULL, then the parent of the @kobj will be set to the
 321  * kobject associted with the kset assigned to this kobject.  If no kset
 322  * is assigned to the kobject, then the kobject will be located in the
 323  * root of the sysfs tree.
 324  *
 325  * If this function returns an error, kobject_put() must be called to
 326  * properly clean up the memory associated with the object.
 327  * Under no instance should the kobject that is passed to this function
 328  * be directly freed with a call to kfree(), that can leak memory.
 329  *
 330  * Note, no "add" uevent will be created with this call, the caller should set
 331  * up all of the necessary sysfs files for the object and then call
 332  * kobject_uevent() with the UEVENT_ADD parameter to ensure that
 333  * userspace is properly notified of this kobject's creation.
 334  */
 335 int kobject_add(struct kobject *kobj, struct kobject *parent,
 336                 const char *fmt, ...)
 337 {
 338         va_list args;
 339         int retval;
 340
 341         if (!kobj)
 342                 return -EINVAL;
 343
 344         if (!kobj->state_initialized) {
 345                 printk(KERN_ERR "kobject '%s' (%p): tried to add an "
 346                        "uninitialized object, something is seriously wrong.\n",
 347                        kobject_name(kobj), kobj);
 348                 dump_stack();
 349                 return -EINVAL;
 350         }
 351         va_start(args, fmt);
 352         retval = kobject_add_varg(kobj, parent, fmt, args);
 353         va_end(args);
 354
 355         return retval;
 356 }
 357 EXPORT_SYMBOL(kobject_add);
 358
 359 /**
 360  * kobject_init_and_add - initialize a kobject structure and add it to the kobject hierarchy
 361  * @kobj: pointer to the kobject to initialize
 362  * @ktype: pointer to the ktype for this kobject.
 363  * @parent: pointer to the parent of this kobject.
 364  * @fmt: the name of the kobject.
 365  *
 366  * This function combines the call to kobject_init() and
 367  * kobject_add().  The same type of error handling after a call to
 368  * kobject_add() and kobject lifetime rules are the same here.
 369  */
 370 int kobject_init_and_add(struct kobject *kobj, struct kobj_type *ktype,
 371                          struct kobject *parent, const char *fmt, ...)
 372 {
 373         va_list args;
 374         int retval;
 375
 376         kobject_init(kobj, ktype);
 377
 378         va_start(args, fmt);
 379         retval = kobject_add_varg(kobj, parent, fmt, args);
 380         va_end(args);
 381
 382         return retval;
 383 }
 384 EXPORT_SYMBOL_GPL(kobject_init_and_add);
 385
 386 /**
 387  * kobject_rename - change the name of an object
 388  * @kobj: object in question.
 389  * @new_name: object's new name
 390  *
 391  * It is the responsibility of the caller to provide mutual
 392  * exclusion between two different calls of kobject_rename
 393  * on the same kobject and to ensure that new_name is valid and
 394  * won't conflict with other kobjects.
 395  */
 396 int kobject_rename(struct kobject *kobj, const char *new_name)
 397 {
 398         int error = 0;
 399         const char *devpath = NULL;
 400         const char *dup_name = NULL, *name;
 401         char *devpath_string = NULL;
 402         char *envp[2];
 403
 404         kobj = kobject_get(kobj);
 405         if (!kobj)
 406                 return -EINVAL;
 407         if (!kobj->parent)
 408                 return -EINVAL;
 409
 410         devpath = kobject_get_path(kobj, GFP_KERNEL);
 411         if (!devpath) {
 412                 error = -ENOMEM;
 413                 goto out;
 414         }
 415         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 416         if (!devpath_string) {
 417                 error = -ENOMEM;
 418                 goto out;
 419         }
 420         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 421         envp[0] = devpath_string;
 422         envp[1] = NULL;
 423
 424         name = dup_name = kstrdup(new_name, GFP_KERNEL);
 425         if (!name) {
 426                 error = -ENOMEM;
 427                 goto out;
 428         }
 429
 430         error = sysfs_rename_dir(kobj, new_name);
 431         if (error)
 432                 goto out;
 433
 434         /* Install the new kobject name */
 435         dup_name = kobj->name;
 436         kobj->name = name;
 437
 438         /* This function is mostly/only used for network interface.
 439          * Some hotplug package track interfaces by their name and
 440          * therefore want to know when the name is changed by the user. */
 441         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 442
 443 out:
 444         kfree(dup_name);
 445         kfree(devpath_string);
 446         kfree(devpath);
 447         kobject_put(kobj);
 448
 449         return error;
 450 }
 451 EXPORT_SYMBOL_GPL(kobject_rename);
 452
 453 /**
 454  * kobject_move - move object to another parent
 455  * @kobj: object in question.
 456  * @new_parent: object's new parent (can be NULL)
 457  */
 458 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 459 {
 460         int error;
 461         struct kobject *old_parent;
 462         const char *devpath = NULL;
 463         char *devpath_string = NULL;
 464         char *envp[2];
 465
 466         kobj = kobject_get(kobj);
 467         if (!kobj)
 468                 return -EINVAL;
 469         new_parent = kobject_get(new_parent);
 470         if (!new_parent) {
 471                 if (kobj->kset)
 472                         new_parent = kobject_get(&kobj->kset->kobj);
 473         }
 474         /* old object path */
 475         devpath = kobject_get_path(kobj, GFP_KERNEL);
 476         if (!devpath) {
 477                 error = -ENOMEM;
 478                 goto out;
 479         }
 480         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 481         if (!devpath_string) {
 482                 error = -ENOMEM;
 483                 goto out;
 484         }
 485         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 486         envp[0] = devpath_string;
 487         envp[1] = NULL;
 488         error = sysfs_move_dir(kobj, new_parent);
 489         if (error)
 490                 goto out;
 491         old_parent = kobj->parent;
 492         kobj->parent = new_parent;
 493         new_parent = NULL;
 494         kobject_put(old_parent);
 495         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 496 out:
 497         kobject_put(new_parent);
 498         kobject_put(kobj);
 499         kfree(devpath_string);
 500         kfree(devpath);
 501         return error;
 502 }
 503
 504 /**
 505  * kobject_del - unlink kobject from hierarchy.
 506  * @kobj: object.
 507  */
 508 void kobject_del(struct kobject *kobj)
 509 {
 510         if (!kobj)
 511                 return;
 512
 513         sysfs_remove_dir(kobj);
 514         kobj->state_in_sysfs = 0;
 515         kobj_kset_leave(kobj);
 516         kobject_put(kobj->parent);
 517         kobj->parent = NULL;
 518 }
 519
 520 /**
 521  * kobject_get - increment refcount for object.
 522  * @kobj: object.
 523  */
 524 struct kobject *kobject_get(struct kobject *kobj)
 525 {
 526         if (kobj)
 527                 kref_get(&kobj->kref);
 528         return kobj;
 529 }
 530
 531 /*
 532  * kobject_cleanup - free kobject resources.
 533  * @kobj: object to cleanup
 534  */
 535 static void kobject_cleanup(struct kobject *kobj)
 536 {
 537         struct kobj_type *t = get_ktype(kobj);
 538         const char *name = kobj->name;
 539
 540         pr_debug("kobject: '%s' (%p): %s\n",
 541                  kobject_name(kobj), kobj, __func__);
 542
 543         if (t && !t->release)
 544                 pr_debug("kobject: '%s' (%p): does not have a release() "
 545                          "function, it is broken and must be fixed.\n",
 546                          kobject_name(kobj), kobj);
 547
 548         /* send "remove" if the caller did not do it but sent "add" */
 549         if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
 550                 pr_debug("kobject: '%s' (%p): auto cleanup 'remove' event\n",
 551                          kobject_name(kobj), kobj);
 552                 kobject_uevent(kobj, KOBJ_REMOVE);
 553         }
 554
 555         /* remove from sysfs if the caller did not do it */
 556         if (kobj->state_in_sysfs) {
 557                 pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n",
 558                          kobject_name(kobj), kobj);
 559                 kobject_del(kobj);
 560         }
 561
 562         if (t && t->release) {
 563                 pr_debug("kobject: '%s' (%p): calling ktype release\n",
 564                          kobject_name(kobj), kobj);
 565                 t->release(kobj);
 566         }
 567
 568         /* free name if we allocated it */
 569         if (name) {
 570                 pr_debug("kobject: '%s': free name\n", name);
 571                 kfree(name);
 572         }
 573 }
 574
 575 static void kobject_release(struct kref *kref)
 576 {
 577         kobject_cleanup(container_of(kref, struct kobject, kref));
 578 }
 579
 580 /**
 581  * kobject_put - decrement refcount for object.
 582  * @kobj: object.
 583  *
 584  * Decrement the refcount, and if 0, call kobject_cleanup().
 585  */
 586 void kobject_put(struct kobject *kobj)
 587 {
 588         if (kobj) {
 589                 if (!kobj->state_initialized)
 590                         WARN(1, KERN_WARNING "kobject: '%s' (%p): is not "
 591                                "initialized, yet kobject_put() is being "
 592                                "called.\n", kobject_name(kobj), kobj);
 593                 kref_put(&kobj->kref, kobject_release);
 594         }
 595 }
 596
 597 static void dynamic_kobj_release(struct kobject *kobj)
 598 {
 599         pr_debug("kobject: (%p): %s\n", kobj, __func__);
 600         kfree(kobj);
 601 }
 602
 603 static struct kobj_type dynamic_kobj_ktype = {
 604         .release        = dynamic_kobj_release,
 605         .sysfs_ops      = &kobj_sysfs_ops,
 606 };
 607
 608 /**
 609  * kobject_create - create a struct kobject dynamically
 610  *
 611  * This function creates a kobject structure dynamically and sets it up
 612  * to be a "dynamic" kobject with a default release function set up.
 613  *
 614  * If the kobject was not able to be created, NULL will be returned.
 615  * The kobject structure returned from here must be cleaned up with a
 616  * call to kobject_put() and not kfree(), as kobject_init() has
 617  * already been called on this structure.
 618  */
 619 struct kobject *kobject_create(void)
 620 {
 621         struct kobject *kobj;
 622
 623         kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
 624         if (!kobj)
 625                 return NULL;
 626
 627         kobject_init(kobj, &dynamic_kobj_ktype);
 628         return kobj;
 629 }
 630
 631 /**
 632  * kobject_create_and_add - create a struct kobject dynamically and register it with sysfs
 633  *
 634  * @name: the name for the kset
 635  * @parent: the parent kobject of this kobject, if any.
 636  *
 637  * This function creates a kobject structure dynamically and registers it
 638  * with sysfs.  When you are finished with this structure, call
 639  * kobject_put() and the structure will be dynamically freed when
 640  * it is no longer being used.
 641  *
 642  * If the kobject was not able to be created, NULL will be returned.
 643  */
 644 struct kobject *kobject_create_and_add(const char *name, struct kobject *parent)
 645 {
 646         struct kobject *kobj;
 647         int retval;
 648
 649         kobj = kobject_create();
 650         if (!kobj)
 651                 return NULL;
 652
 653         retval = kobject_add(kobj, parent, "%s", name);
 654         if (retval) {
 655                 printk(KERN_WARNING "%s: kobject_add error: %d\n",
 656                        __func__, retval);
 657                 kobject_put(kobj);
 658                 kobj = NULL;
 659         }
 660         return kobj;
 661 }
 662 EXPORT_SYMBOL_GPL(kobject_create_and_add);
 663
 664 /**
 665  * kset_init - initialize a kset for use
 666  * @k: kset
 667  */
 668 void kset_init(struct kset *k)
 669 {
 670         kobject_init_internal(&k->kobj);
 671         INIT_LIST_HEAD(&k->list);
 672         spin_lock_init(&k->list_lock);
 673 }
 674
 675 /* default kobject attribute operations */
 676 static ssize_t kobj_attr_show(struct kobject *kobj, struct attribute *attr,
 677                               char *buf)
 678 {
 679         struct kobj_attribute *kattr;
 680         ssize_t ret = -EIO;
 681
 682         kattr = container_of(attr, struct kobj_attribute, attr);
 683         if (kattr->show)
 684                 ret = kattr->show(kobj, kattr, buf);
 685         return ret;
 686 }
 687
 688 static ssize_t kobj_attr_store(struct kobject *kobj, struct attribute *attr,
 689                                const char *buf, size_t count)
 690 {
 691         struct kobj_attribute *kattr;
 692         ssize_t ret = -EIO;
 693
 694         kattr = container_of(attr, struct kobj_attribute, attr);
 695         if (kattr->store)
 696                 ret = kattr->store(kobj, kattr, buf, count);
 697         return ret;
 698 }
 699
 700 struct sysfs_ops kobj_sysfs_ops = {
 701         .show   = kobj_attr_show,
 702         .store  = kobj_attr_store,
 703 };
 704
 705 /**
 706  * kset_register - initialize and add a kset.
 707  * @k: kset.
 708  */
 709 int kset_register(struct kset *k)
 710 {
 711         int err;
 712
 713         if (!k)
 714                 return -EINVAL;
 715
 716         kset_init(k);
 717         err = kobject_add_internal(&k->kobj);
 718         if (err)
 719                 return err;
 720         kobject_uevent(&k->kobj, KOBJ_ADD);
 721         return 0;
 722 }
 723
 724 /**
 725  * kset_unregister - remove a kset.
 726  * @k: kset.
 727  */
 728 void kset_unregister(struct kset *k)
 729 {
 730         if (!k)
 731                 return;
 732         kobject_put(&k->kobj);
 733 }
 734
 735 /**
 736  * kset_find_obj - search for object in kset.
 737  * @kset: kset we're looking in.
 738  * @name: object's name.
 739  *
 740  * Lock kset via @kset->subsys, and iterate over @kset->list,
 741  * looking for a matching kobject. If matching object is found
 742  * take a reference and return the object.
 743  */
 744 struct kobject *kset_find_obj(struct kset *kset, const char *name)
 745 {
 746         struct kobject *k;
 747         struct kobject *ret = NULL;
 748
 749         spin_lock(&kset->list_lock);
 750         list_for_each_entry(k, &kset->list, entry) {
 751                 if (kobject_name(k) && !strcmp(kobject_name(k), name)) {
 752                         ret = kobject_get(k);
 753                         break;
 754                 }
 755         }
 756         spin_unlock(&kset->list_lock);
 757         return ret;
 758 }
 759
 760 static void kset_release(struct kobject *kobj)
 761 {
 762         struct kset *kset = container_of(kobj, struct kset, kobj);
 763         pr_debug("kobject: '%s' (%p): %s\n",
 764                  kobject_name(kobj), kobj, __func__);
 765         kfree(kset);
 766 }
 767
 768 static struct kobj_type kset_ktype = {
 769         .sysfs_ops      = &kobj_sysfs_ops,
 770         .release = kset_release,
 771 };
 772
 773 /**
 774  * kset_create - create a struct kset dynamically
 775  *
 776  * @name: the name for the kset
 777  * @uevent_ops: a struct kset_uevent_ops for the kset
 778  * @parent_kobj: the parent kobject of this kset, if any.
 779  *
 780  * This function creates a kset structure dynamically.  This structure can
 781  * then be registered with the system and show up in sysfs with a call to
 782  * kset_register().  When you are finished with this structure, if
 783  * kset_register() has been called, call kset_unregister() and the
 784  * structure will be dynamically freed when it is no longer being used.
 785  *
 786  * If the kset was not able to be created, NULL will be returned.
 787  */
 788 static struct kset *kset_create(const char *name,
 789                                 struct kset_uevent_ops *uevent_ops,
 790                                 struct kobject *parent_kobj)
 791 {
 792         struct kset *kset;
 793
 794         kset = kzalloc(sizeof(*kset), GFP_KERNEL);
 795         if (!kset)
 796                 return NULL;
 797         kobject_set_name(&kset->kobj, name);
 798         kset->uevent_ops = uevent_ops;
 799         kset->kobj.parent = parent_kobj;
 800
 801         /*
 802          * The kobject of this kset will have a type of kset_ktype and belong to
 803          * no kset itself.  That way we can properly free it when it is
 804          * finished being used.
 805          */
 806         kset->kobj.ktype = &kset_ktype;
 807         kset->kobj.kset = NULL;
 808
 809         return kset;
 810 }
 811
 812 /**
 813  * kset_create_and_add - create a struct kset dynamically and add it to sysfs
 814  *
 815  * @name: the name for the kset
 816  * @uevent_ops: a struct kset_uevent_ops for the kset
 817  * @parent_kobj: the parent kobject of this kset, if any.
 818  *
 819  * This function creates a kset structure dynamically and registers it
 820  * with sysfs.  When you are finished with this structure, call
 821  * kset_unregister() and the structure will be dynamically freed when it
 822  * is no longer being used.
 823  *
 824  * If the kset was not able to be created, NULL will be returned.
 825  */
 826 struct kset *kset_create_and_add(const char *name,
 827                                  struct kset_uevent_ops *uevent_ops,
 828                                  struct kobject *parent_kobj)
 829 {
 830         struct kset *kset;
 831         int error;
 832
 833         kset = kset_create(name, uevent_ops, parent_kobj);
 834         if (!kset)
 835                 return NULL;
 836         error = kset_register(kset);
 837         if (error) {
 838                 kfree(kset);
 839                 return NULL;
 840         }
 841         return kset;
 842 }
 843 EXPORT_SYMBOL_GPL(kset_create_and_add);
 844
 845 EXPORT_SYMBOL(kobject_get);
 846 EXPORT_SYMBOL(kobject_put);
 847 EXPORT_SYMBOL(kobject_del);
 848
 849 EXPORT_SYMBOL(kset_register);
 850 EXPORT_SYMBOL(kset_unregister);