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 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         if (kobj->name && !fmt)
 222                 return 0;
 223
 224         kobj->name = kvasprintf(GFP_KERNEL, fmt, vargs);
 225         if (!kobj->name)
 226                 return -ENOMEM;
 227
 228         /* ewww... some of these buggers have '/' in the name ... */
 229         while ((s = strchr(kobj->name, '/')))
 230                 s[0] = '!';
 231
 232         kfree(old_name);
 233         return 0;
 234 }
 235
 236 /**
 237  * kobject_set_name - Set the name of a kobject
 238  * @kobj: struct kobject to set the name of
 239  * @fmt: format string used to build the name
 240  *
 241  * This sets the name of the kobject.  If you have already added the
 242  * kobject to the system, you must call kobject_rename() in order to
 243  * change the name of the kobject.
 244  */
 245 int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
 246 {
 247         va_list vargs;
 248         int retval;
 249
 250         va_start(vargs, fmt);
 251         retval = kobject_set_name_vargs(kobj, fmt, vargs);
 252         va_end(vargs);
 253
 254         return retval;
 255 }
 256 EXPORT_SYMBOL(kobject_set_name);
 257
 258 /**
 259  * kobject_init - initialize a kobject structure
 260  * @kobj: pointer to the kobject to initialize
 261  * @ktype: pointer to the ktype for this kobject.
 262  *
 263  * This function will properly initialize a kobject such that it can then
 264  * be passed to the kobject_add() call.
 265  *
 266  * After this function is called, the kobject MUST be cleaned up by a call
 267  * to kobject_put(), not by a call to kfree directly to ensure that all of
 268  * the memory is cleaned up properly.
 269  */
 270 void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
 271 {
 272         char *err_str;
 273
 274         if (!kobj) {
 275                 err_str = "invalid kobject pointer!";
 276                 goto error;
 277         }
 278         if (!ktype) {
 279                 err_str = "must have a ktype to be initialized properly!\n";
 280                 goto error;
 281         }
 282         if (kobj->state_initialized) {
 283                 /* do not error out as sometimes we can recover */
 284                 printk(KERN_ERR "kobject (%p): tried to init an initialized "
 285                        "object, something is seriously wrong.\n", kobj);
 286                 dump_stack();
 287         }
 288
 289         kobject_init_internal(kobj);
 290         kobj->ktype = ktype;
 291         return;
 292
 293 error:
 294         printk(KERN_ERR "kobject (%p): %s\n", kobj, err_str);
 295         dump_stack();
 296 }
 297 EXPORT_SYMBOL(kobject_init);
 298
 299 static int kobject_add_varg(struct kobject *kobj, struct kobject *parent,
 300                             const char *fmt, va_list vargs)
 301 {
 302         int retval;
 303
 304         retval = kobject_set_name_vargs(kobj, fmt, vargs);
 305         if (retval) {
 306                 printk(KERN_ERR "kobject: can not set name properly!\n");
 307                 return retval;
 308         }
 309         kobj->parent = parent;
 310         return kobject_add_internal(kobj);
 311 }
 312
 313 /**
 314  * kobject_add - the main kobject add function
 315  * @kobj: the kobject to add
 316  * @parent: pointer to the parent of the kobject.
 317  * @fmt: format to name the kobject with.
 318  *
 319  * The kobject name is set and added to the kobject hierarchy in this
 320  * function.
 321  *
 322  * If @parent is set, then the parent of the @kobj will be set to it.
 323  * If @parent is NULL, then the parent of the @kobj will be set to the
 324  * kobject associted with the kset assigned to this kobject.  If no kset
 325  * is assigned to the kobject, then the kobject will be located in the
 326  * root of the sysfs tree.
 327  *
 328  * If this function returns an error, kobject_put() must be called to
 329  * properly clean up the memory associated with the object.
 330  * Under no instance should the kobject that is passed to this function
 331  * be directly freed with a call to kfree(), that can leak memory.
 332  *
 333  * Note, no "add" uevent will be created with this call, the caller should set
 334  * up all of the necessary sysfs files for the object and then call
 335  * kobject_uevent() with the UEVENT_ADD parameter to ensure that
 336  * userspace is properly notified of this kobject's creation.
 337  */
 338 int kobject_add(struct kobject *kobj, struct kobject *parent,
 339                 const char *fmt, ...)
 340 {
 341         va_list args;
 342         int retval;
 343
 344         if (!kobj)
 345                 return -EINVAL;
 346
 347         if (!kobj->state_initialized) {
 348                 printk(KERN_ERR "kobject '%s' (%p): tried to add an "
 349                        "uninitialized object, something is seriously wrong.\n",
 350                        kobject_name(kobj), kobj);
 351                 dump_stack();
 352                 return -EINVAL;
 353         }
 354         va_start(args, fmt);
 355         retval = kobject_add_varg(kobj, parent, fmt, args);
 356         va_end(args);
 357
 358         return retval;
 359 }
 360 EXPORT_SYMBOL(kobject_add);
 361
 362 /**
 363  * kobject_init_and_add - initialize a kobject structure and add it to the kobject hierarchy
 364  * @kobj: pointer to the kobject to initialize
 365  * @ktype: pointer to the ktype for this kobject.
 366  * @parent: pointer to the parent of this kobject.
 367  * @fmt: the name of the kobject.
 368  *
 369  * This function combines the call to kobject_init() and
 370  * kobject_add().  The same type of error handling after a call to
 371  * kobject_add() and kobject lifetime rules are the same here.
 372  */
 373 int kobject_init_and_add(struct kobject *kobj, struct kobj_type *ktype,
 374                          struct kobject *parent, const char *fmt, ...)
 375 {
 376         va_list args;
 377         int retval;
 378
 379         kobject_init(kobj, ktype);
 380
 381         va_start(args, fmt);
 382         retval = kobject_add_varg(kobj, parent, fmt, args);
 383         va_end(args);
 384
 385         return retval;
 386 }
 387 EXPORT_SYMBOL_GPL(kobject_init_and_add);
 388
 389 /**
 390  * kobject_rename - change the name of an object
 391  * @kobj: object in question.
 392  * @new_name: object's new name
 393  *
 394  * It is the responsibility of the caller to provide mutual
 395  * exclusion between two different calls of kobject_rename
 396  * on the same kobject and to ensure that new_name is valid and
 397  * won't conflict with other kobjects.
 398  */
 399 int kobject_rename(struct kobject *kobj, const char *new_name)
 400 {
 401         int error = 0;
 402         const char *devpath = NULL;
 403         const char *dup_name = NULL, *name;
 404         char *devpath_string = NULL;
 405         char *envp[2];
 406
 407         kobj = kobject_get(kobj);
 408         if (!kobj)
 409                 return -EINVAL;
 410         if (!kobj->parent)
 411                 return -EINVAL;
 412
 413         devpath = kobject_get_path(kobj, GFP_KERNEL);
 414         if (!devpath) {
 415                 error = -ENOMEM;
 416                 goto out;
 417         }
 418         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 419         if (!devpath_string) {
 420                 error = -ENOMEM;
 421                 goto out;
 422         }
 423         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 424         envp[0] = devpath_string;
 425         envp[1] = NULL;
 426
 427         name = dup_name = kstrdup(new_name, GFP_KERNEL);
 428         if (!name) {
 429                 error = -ENOMEM;
 430                 goto out;
 431         }
 432
 433         error = sysfs_rename_dir(kobj, new_name);
 434         if (error)
 435                 goto out;
 436
 437         /* Install the new kobject name */
 438         dup_name = kobj->name;
 439         kobj->name = name;
 440
 441         /* This function is mostly/only used for network interface.
 442          * Some hotplug package track interfaces by their name and
 443          * therefore want to know when the name is changed by the user. */
 444         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 445
 446 out:
 447         kfree(dup_name);
 448         kfree(devpath_string);
 449         kfree(devpath);
 450         kobject_put(kobj);
 451
 452         return error;
 453 }
 454 EXPORT_SYMBOL_GPL(kobject_rename);
 455
 456 /**
 457  * kobject_move - move object to another parent
 458  * @kobj: object in question.
 459  * @new_parent: object's new parent (can be NULL)
 460  */
 461 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 462 {
 463         int error;
 464         struct kobject *old_parent;
 465         const char *devpath = NULL;
 466         char *devpath_string = NULL;
 467         char *envp[2];
 468
 469         kobj = kobject_get(kobj);
 470         if (!kobj)
 471                 return -EINVAL;
 472         new_parent = kobject_get(new_parent);
 473         if (!new_parent) {
 474                 if (kobj->kset)
 475                         new_parent = kobject_get(&kobj->kset->kobj);
 476         }
 477         /* old object path */
 478         devpath = kobject_get_path(kobj, GFP_KERNEL);
 479         if (!devpath) {
 480                 error = -ENOMEM;
 481                 goto out;
 482         }
 483         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 484         if (!devpath_string) {
 485                 error = -ENOMEM;
 486                 goto out;
 487         }
 488         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 489         envp[0] = devpath_string;
 490         envp[1] = NULL;
 491         error = sysfs_move_dir(kobj, new_parent);
 492         if (error)
 493                 goto out;
 494         old_parent = kobj->parent;
 495         kobj->parent = new_parent;
 496         new_parent = NULL;
 497         kobject_put(old_parent);
 498         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 499 out:
 500         kobject_put(new_parent);
 501         kobject_put(kobj);
 502         kfree(devpath_string);
 503         kfree(devpath);
 504         return error;
 505 }
 506
 507 /**
 508  * kobject_del - unlink kobject from hierarchy.
 509  * @kobj: object.
 510  */
 511 void kobject_del(struct kobject *kobj)
 512 {
 513         if (!kobj)
 514                 return;
 515
 516         sysfs_remove_dir(kobj);
 517         kobj->state_in_sysfs = 0;
 518         kobj_kset_leave(kobj);
 519         kobject_put(kobj->parent);
 520         kobj->parent = NULL;
 521 }
 522
 523 /**
 524  * kobject_get - increment refcount for object.
 525  * @kobj: object.
 526  */
 527 struct kobject *kobject_get(struct kobject *kobj)
 528 {
 529         if (kobj)
 530                 kref_get(&kobj->kref);
 531         return kobj;
 532 }
 533
 534 /*
 535  * kobject_cleanup - free kobject resources.
 536  * @kobj: object to cleanup
 537  */
 538 static void kobject_cleanup(struct kobject *kobj)
 539 {
 540         struct kobj_type *t = get_ktype(kobj);
 541         const char *name = kobj->name;
 542
 543         pr_debug("kobject: '%s' (%p): %s\n",
 544                  kobject_name(kobj), kobj, __func__);
 545
 546         if (t && !t->release)
 547                 pr_debug("kobject: '%s' (%p): does not have a release() "
 548                          "function, it is broken and must be fixed.\n",
 549                          kobject_name(kobj), kobj);
 550
 551         /* send "remove" if the caller did not do it but sent "add" */
 552         if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
 553                 pr_debug("kobject: '%s' (%p): auto cleanup 'remove' event\n",
 554                          kobject_name(kobj), kobj);
 555                 kobject_uevent(kobj, KOBJ_REMOVE);
 556         }
 557
 558         /* remove from sysfs if the caller did not do it */
 559         if (kobj->state_in_sysfs) {
 560                 pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n",
 561                          kobject_name(kobj), kobj);
 562                 kobject_del(kobj);
 563         }
 564
 565         if (t && t->release) {
 566                 pr_debug("kobject: '%s' (%p): calling ktype release\n",
 567                          kobject_name(kobj), kobj);
 568                 t->release(kobj);
 569         }
 570
 571         /* free name if we allocated it */
 572         if (name) {
 573                 pr_debug("kobject: '%s': free name\n", name);
 574                 kfree(name);
 575         }
 576 }
 577
 578 static void kobject_release(struct kref *kref)
 579 {
 580         kobject_cleanup(container_of(kref, struct kobject, kref));
 581 }
 582
 583 /**
 584  * kobject_put - decrement refcount for object.
 585  * @kobj: object.
 586  *
 587  * Decrement the refcount, and if 0, call kobject_cleanup().
 588  */
 589 void kobject_put(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_put() is being "
 595                                "called.\n", kobject_name(kobj), kobj);
 596                 kref_put(&kobj->kref, kobject_release);
 597         }
 598 }
 599
 600 static void dynamic_kobj_release(struct kobject *kobj)
 601 {
 602         pr_debug("kobject: (%p): %s\n", kobj, __func__);
 603         kfree(kobj);
 604 }
 605
 606 static struct kobj_type dynamic_kobj_ktype = {
 607         .release        = dynamic_kobj_release,
 608         .sysfs_ops      = &kobj_sysfs_ops,
 609 };
 610
 611 /**
 612  * kobject_create - create a struct kobject dynamically
 613  *
 614  * This function creates a kobject structure dynamically and sets it up
 615  * to be a "dynamic" kobject with a default release function set up.
 616  *
 617  * If the kobject was not able to be created, NULL will be returned.
 618  * The kobject structure returned from here must be cleaned up with a
 619  * call to kobject_put() and not kfree(), as kobject_init() has
 620  * already been called on this structure.
 621  */
 622 struct kobject *kobject_create(void)
 623 {
 624         struct kobject *kobj;
 625
 626         kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
 627         if (!kobj)
 628                 return NULL;
 629
 630         kobject_init(kobj, &dynamic_kobj_ktype);
 631         return kobj;
 632 }
 633
 634 /**
 635  * kobject_create_and_add - create a struct kobject dynamically and register it with sysfs
 636  *
 637  * @name: the name for the kset
 638  * @parent: the parent kobject of this kobject, if any.
 639  *
 640  * This function creates a kobject structure dynamically and registers it
 641  * with sysfs.  When you are finished with this structure, call
 642  * kobject_put() and the structure will be dynamically freed when
 643  * it is no longer being used.
 644  *
 645  * If the kobject was not able to be created, NULL will be returned.
 646  */
 647 struct kobject *kobject_create_and_add(const char *name, struct kobject *parent)
 648 {
 649         struct kobject *kobj;
 650         int retval;
 651
 652         kobj = kobject_create();
 653         if (!kobj)
 654                 return NULL;
 655
 656         retval = kobject_add(kobj, parent, "%s", name);
 657         if (retval) {
 658                 printk(KERN_WARNING "%s: kobject_add error: %d\n",
 659                        __func__, retval);
 660                 kobject_put(kobj);
 661                 kobj = NULL;
 662         }
 663         return kobj;
 664 }
 665 EXPORT_SYMBOL_GPL(kobject_create_and_add);
 666
 667 /**
 668  * kset_init - initialize a kset for use
 669  * @k: kset
 670  */
 671 void kset_init(struct kset *k)
 672 {
 673         kobject_init_internal(&k->kobj);
 674         INIT_LIST_HEAD(&k->list);
 675         spin_lock_init(&k->list_lock);
 676 }
 677
 678 /* default kobject attribute operations */
 679 static ssize_t kobj_attr_show(struct kobject *kobj, struct attribute *attr,
 680                               char *buf)
 681 {
 682         struct kobj_attribute *kattr;
 683         ssize_t ret = -EIO;
 684
 685         kattr = container_of(attr, struct kobj_attribute, attr);
 686         if (kattr->show)
 687                 ret = kattr->show(kobj, kattr, buf);
 688         return ret;
 689 }
 690
 691 static ssize_t kobj_attr_store(struct kobject *kobj, struct attribute *attr,
 692                                const char *buf, size_t count)
 693 {
 694         struct kobj_attribute *kattr;
 695         ssize_t ret = -EIO;
 696
 697         kattr = container_of(attr, struct kobj_attribute, attr);
 698         if (kattr->store)
 699                 ret = kattr->store(kobj, kattr, buf, count);
 700         return ret;
 701 }
 702
 703 struct sysfs_ops kobj_sysfs_ops = {
 704         .show   = kobj_attr_show,
 705         .store  = kobj_attr_store,
 706 };
 707
 708 /**
 709  * kset_register - initialize and add a kset.
 710  * @k: kset.
 711  */
 712 int kset_register(struct kset *k)
 713 {
 714         int err;
 715
 716         if (!k)
 717                 return -EINVAL;
 718
 719         kset_init(k);
 720         err = kobject_add_internal(&k->kobj);
 721         if (err)
 722                 return err;
 723         kobject_uevent(&k->kobj, KOBJ_ADD);
 724         return 0;
 725 }
 726
 727 /**
 728  * kset_unregister - remove a kset.
 729  * @k: kset.
 730  */
 731 void kset_unregister(struct kset *k)
 732 {
 733         if (!k)
 734                 return;
 735         kobject_put(&k->kobj);
 736 }
 737
 738 /**
 739  * kset_find_obj - search for object in kset.
 740  * @kset: kset we're looking in.
 741  * @name: object's name.
 742  *
 743  * Lock kset via @kset->subsys, and iterate over @kset->list,
 744  * looking for a matching kobject. If matching object is found
 745  * take a reference and return the object.
 746  */
 747 struct kobject *kset_find_obj(struct kset *kset, const char *name)
 748 {
 749         struct kobject *k;
 750         struct kobject *ret = NULL;
 751
 752         spin_lock(&kset->list_lock);
 753         list_for_each_entry(k, &kset->list, entry) {
 754                 if (kobject_name(k) && !strcmp(kobject_name(k), name)) {
 755                         ret = kobject_get(k);
 756                         break;
 757                 }
 758         }
 759         spin_unlock(&kset->list_lock);
 760         return ret;
 761 }
 762
 763 static void kset_release(struct kobject *kobj)
 764 {
 765         struct kset *kset = container_of(kobj, struct kset, kobj);
 766         pr_debug("kobject: '%s' (%p): %s\n",
 767                  kobject_name(kobj), kobj, __func__);
 768         kfree(kset);
 769 }
 770
 771 static struct kobj_type kset_ktype = {
 772         .sysfs_ops      = &kobj_sysfs_ops,
 773         .release = kset_release,
 774 };
 775
 776 /**
 777  * kset_create - create a struct kset dynamically
 778  *
 779  * @name: the name for the kset
 780  * @uevent_ops: a struct kset_uevent_ops for the kset
 781  * @parent_kobj: the parent kobject of this kset, if any.
 782  *
 783  * This function creates a kset structure dynamically.  This structure can
 784  * then be registered with the system and show up in sysfs with a call to
 785  * kset_register().  When you are finished with this structure, if
 786  * kset_register() has been called, call kset_unregister() and the
 787  * structure will be dynamically freed when it is no longer being used.
 788  *
 789  * If the kset was not able to be created, NULL will be returned.
 790  */
 791 static struct kset *kset_create(const char *name,
 792                                 struct kset_uevent_ops *uevent_ops,
 793                                 struct kobject *parent_kobj)
 794 {
 795         struct kset *kset;
 796         int retval;
 797
 798         kset = kzalloc(sizeof(*kset), GFP_KERNEL);
 799         if (!kset)
 800                 return NULL;
 801         retval = kobject_set_name(&kset->kobj, name);
 802         if (retval) {
 803                 kfree(kset);
 804                 return NULL;
 805         }
 806         kset->uevent_ops = uevent_ops;
 807         kset->kobj.parent = parent_kobj;
 808
 809         /*
 810          * The kobject of this kset will have a type of kset_ktype and belong to
 811          * no kset itself.  That way we can properly free it when it is
 812          * finished being used.
 813          */
 814         kset->kobj.ktype = &kset_ktype;
 815         kset->kobj.kset = NULL;
 816
 817         return kset;
 818 }
 819
 820 /**
 821  * kset_create_and_add - create a struct kset dynamically and add it to sysfs
 822  *
 823  * @name: the name for the kset
 824  * @uevent_ops: a struct kset_uevent_ops for the kset
 825  * @parent_kobj: the parent kobject of this kset, if any.
 826  *
 827  * This function creates a kset structure dynamically and registers it
 828  * with sysfs.  When you are finished with this structure, call
 829  * kset_unregister() and the structure will be dynamically freed when it
 830  * is no longer being used.
 831  *
 832  * If the kset was not able to be created, NULL will be returned.
 833  */
 834 struct kset *kset_create_and_add(const char *name,
 835                                  struct kset_uevent_ops *uevent_ops,
 836                                  struct kobject *parent_kobj)
 837 {
 838         struct kset *kset;
 839         int error;
 840
 841         kset = kset_create(name, uevent_ops, parent_kobj);
 842         if (!kset)
 843                 return NULL;
 844         error = kset_register(kset);
 845         if (error) {
 846                 kfree(kset);
 847                 return NULL;
 848         }
 849         return kset;
 850 }
 851 EXPORT_SYMBOL_GPL(kset_create_and_add);
 852
 853 EXPORT_SYMBOL(kobject_get);
 854 EXPORT_SYMBOL(kobject_put);
 855 EXPORT_SYMBOL(kobject_del);
 856
 857 EXPORT_SYMBOL(kset_register);
 858 EXPORT_SYMBOL(kset_unregister);