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