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 inline struct kobject *to_kobj(struct list_head *entry)
  62 {
  63         return container_of(entry, struct kobject, entry);
  64 }
  65
  66 static int get_kobj_path_length(struct kobject *kobj)
  67 {
  68         int length = 1;
  69         struct kobject *parent = kobj;
  70
  71         /* walk up the ancestors until we hit the one pointing to the
  72          * root.
  73          * Add 1 to strlen for leading '/' of each level.
  74          */
  75         do {
  76                 if (kobject_name(parent) == NULL)
  77                         return 0;
  78                 length += strlen(kobject_name(parent)) + 1;
  79                 parent = parent->parent;
  80         } while (parent);
  81         return length;
  82 }
  83
  84 static void fill_kobj_path(struct kobject *kobj, char *path, int length)
  85 {
  86         struct kobject *parent;
  87
  88         --length;
  89         for (parent = kobj; parent; parent = parent->parent) {
  90                 int cur = strlen(kobject_name(parent));
  91                 /* back up enough to print this name with '/' */
  92                 length -= cur;
  93                 strncpy(path + length, kobject_name(parent), cur);
  94                 *(path + --length) = '/';
  95         }
  96
  97         pr_debug("kobject: '%s' (%p): %s: path = '%s'\n", kobject_name(kobj),
  98                  kobj, __FUNCTION__, path);
  99 }
 100
 101 /**
 102  * kobject_get_path - generate and return the path associated with a given kobj and kset pair.
 103  *
 104  * @kobj:       kobject in question, with which to build the path
 105  * @gfp_mask:   the allocation type used to allocate the path
 106  *
 107  * The result must be freed by the caller with kfree().
 108  */
 109 char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
 110 {
 111         char *path;
 112         int len;
 113
 114         len = get_kobj_path_length(kobj);
 115         if (len == 0)
 116                 return NULL;
 117         path = kzalloc(len, gfp_mask);
 118         if (!path)
 119                 return NULL;
 120         fill_kobj_path(kobj, path, len);
 121
 122         return path;
 123 }
 124 EXPORT_SYMBOL_GPL(kobject_get_path);
 125
 126 /* add the kobject to its kset's list */
 127 static void kobj_kset_join(struct kobject *kobj)
 128 {
 129         if (!kobj->kset)
 130                 return;
 131
 132         kset_get(kobj->kset);
 133         spin_lock(&kobj->kset->list_lock);
 134         list_add_tail(&kobj->entry, &kobj->kset->list);
 135         spin_unlock(&kobj->kset->list_lock);
 136 }
 137
 138 /* remove the kobject from its kset's list */
 139 static void kobj_kset_leave(struct kobject *kobj)
 140 {
 141         if (!kobj->kset)
 142                 return;
 143
 144         spin_lock(&kobj->kset->list_lock);
 145         list_del_init(&kobj->entry);
 146         spin_unlock(&kobj->kset->list_lock);
 147         kset_put(kobj->kset);
 148 }
 149
 150 static void kobject_init_internal(struct kobject *kobj)
 151 {
 152         if (!kobj)
 153                 return;
 154         kref_init(&kobj->kref);
 155         INIT_LIST_HEAD(&kobj->entry);
 156 }
 157
 158
 159 static int kobject_add_internal(struct kobject *kobj)
 160 {
 161         int error = 0;
 162         struct kobject *parent;
 163
 164         if (!kobj)
 165                 return -ENOENT;
 166
 167         if (!kobj->name || !kobj->name[0]) {
 168                 pr_debug("kobject: (%p): attempted to be registered with empty "
 169                          "name!\n", kobj);
 170                 WARN_ON(1);
 171                 return -EINVAL;
 172         }
 173
 174         parent = kobject_get(kobj->parent);
 175
 176         /* join kset if set, use it as parent if we do not already have one */
 177         if (kobj->kset) {
 178                 if (!parent)
 179                         parent = kobject_get(&kobj->kset->kobj);
 180                 kobj_kset_join(kobj);
 181                 kobj->parent = parent;
 182         }
 183
 184         pr_debug("kobject: '%s' (%p): %s: parent: '%s', set: '%s'\n",
 185                  kobject_name(kobj), kobj, __FUNCTION__,
 186                  parent ? kobject_name(parent) : "<NULL>",
 187                  kobj->kset ? kobject_name(&kobj->kset->kobj) : "<NULL>");
 188
 189         error = create_dir(kobj);
 190         if (error) {
 191                 kobj_kset_leave(kobj);
 192                 kobject_put(parent);
 193                 kobj->parent = NULL;
 194
 195                 /* be noisy on error issues */
 196                 if (error == -EEXIST)
 197                         printk(KERN_ERR "%s failed for %s with "
 198                                "-EEXIST, don't try to register things with "
 199                                "the same name in the same directory.\n",
 200                                __FUNCTION__, kobject_name(kobj));
 201                 else
 202                         printk(KERN_ERR "%s failed for %s (%d)\n",
 203                                __FUNCTION__, kobject_name(kobj), error);
 204                 dump_stack();
 205         } else
 206                 kobj->state_in_sysfs = 1;
 207
 208         return error;
 209 }
 210
 211 /**
 212  * kobject_set_name_vargs - Set the name of an kobject
 213  * @kobj: struct kobject to set the name of
 214  * @fmt: format string used to build the name
 215  * @vargs: vargs to format the string.
 216  */
 217 static int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
 218                                   va_list vargs)
 219 {
 220         va_list aq;
 221         char *name;
 222
 223         va_copy(aq, vargs);
 224         name = kvasprintf(GFP_KERNEL, fmt, vargs);
 225         va_end(aq);
 226
 227         if (!name)
 228                 return -ENOMEM;
 229
 230         /* Free the old name, if necessary. */
 231         kfree(kobj->name);
 232
 233         /* Now, set the new name */
 234         kobj->name = name;
 235
 236         return 0;
 237 }
 238
 239 /**
 240  * kobject_set_name - Set the name of a kobject
 241  * @kobj: struct kobject to set the name of
 242  * @fmt: format string used to build the name
 243  *
 244  * This sets the name of the kobject.  If you have already added the
 245  * kobject to the system, you must call kobject_rename() in order to
 246  * change the name of the kobject.
 247  */
 248 int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
 249 {
 250         va_list args;
 251         int retval;
 252
 253         va_start(args, fmt);
 254         retval = kobject_set_name_vargs(kobj, fmt, args);
 255         va_end(args);
 256
 257         return retval;
 258 }
 259 EXPORT_SYMBOL(kobject_set_name);
 260
 261 /**
 262  * kobject_init - initialize a kobject structure
 263  * @kobj: pointer to the kobject to initialize
 264  * @ktype: pointer to the ktype for this kobject.
 265  *
 266  * This function will properly initialize a kobject such that it can then
 267  * be passed to the kobject_add() call.
 268  *
 269  * After this function is called, the kobject MUST be cleaned up by a call
 270  * to kobject_put(), not by a call to kfree directly to ensure that all of
 271  * the memory is cleaned up properly.
 272  */
 273 void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
 274 {
 275         char *err_str;
 276
 277         if (!kobj) {
 278                 err_str = "invalid kobject pointer!";
 279                 goto error;
 280         }
 281         if (!ktype) {
 282                 err_str = "must have a ktype to be initialized properly!\n";
 283                 goto error;
 284         }
 285         if (kobj->state_initialized) {
 286                 /* do not error out as sometimes we can recover */
 287                 printk(KERN_ERR "kobject (%p): tried to init an initialized "
 288                        "object, something is seriously wrong.\n", kobj);
 289                 dump_stack();
 290         }
 291
 292         kref_init(&kobj->kref);
 293         INIT_LIST_HEAD(&kobj->entry);
 294         kobj->ktype = ktype;
 295         kobj->state_in_sysfs = 0;
 296         kobj->state_add_uevent_sent = 0;
 297         kobj->state_remove_uevent_sent = 0;
 298         kobj->state_initialized = 1;
 299         return;
 300
 301 error:
 302         printk(KERN_ERR "kobject (%p): %s\n", kobj, err_str);
 303         dump_stack();
 304 }
 305 EXPORT_SYMBOL(kobject_init);
 306
 307 static int kobject_add_varg(struct kobject *kobj, struct kobject *parent,
 308                             const char *fmt, va_list vargs)
 309 {
 310         va_list aq;
 311         int retval;
 312
 313         va_copy(aq, vargs);
 314         retval = kobject_set_name_vargs(kobj, fmt, aq);
 315         va_end(aq);
 316         if (retval) {
 317                 printk(KERN_ERR "kobject: can not set name properly!\n");
 318                 return retval;
 319         }
 320         kobj->parent = parent;
 321         return kobject_add_internal(kobj);
 322 }
 323
 324 /**
 325  * kobject_add - the main kobject add function
 326  * @kobj: the kobject to add
 327  * @parent: pointer to the parent of the kobject.
 328  * @fmt: format to name the kobject with.
 329  *
 330  * The kobject name is set and added to the kobject hierarchy in this
 331  * function.
 332  *
 333  * If @parent is set, then the parent of the @kobj will be set to it.
 334  * If @parent is NULL, then the parent of the @kobj will be set to the
 335  * kobject associted with the kset assigned to this kobject.  If no kset
 336  * is assigned to the kobject, then the kobject will be located in the
 337  * root of the sysfs tree.
 338  *
 339  * If this function returns an error, kobject_put() must be called to
 340  * properly clean up the memory associated with the object.
 341  * Under no instance should the kobject that is passed to this function
 342  * be directly freed with a call to kfree(), that can leak memory.
 343  *
 344  * Note, no "add" uevent will be created with this call, the caller should set
 345  * up all of the necessary sysfs files for the object and then call
 346  * kobject_uevent() with the UEVENT_ADD parameter to ensure that
 347  * userspace is properly notified of this kobject's creation.
 348  */
 349 int kobject_add(struct kobject *kobj, struct kobject *parent,
 350                 const char *fmt, ...)
 351 {
 352         va_list args;
 353         int retval;
 354
 355         if (!kobj)
 356                 return -EINVAL;
 357
 358         if (!kobj->state_initialized) {
 359                 printk(KERN_ERR "kobject '%s' (%p): tried to add an "
 360                        "uninitialized object, something is seriously wrong.\n",
 361                        kobject_name(kobj), kobj);
 362                 dump_stack();
 363                 return -EINVAL;
 364         }
 365         va_start(args, fmt);
 366         retval = kobject_add_varg(kobj, parent, fmt, args);
 367         va_end(args);
 368
 369         return retval;
 370 }
 371 EXPORT_SYMBOL(kobject_add);
 372
 373 /**
 374  * kobject_init_and_add - initialize a kobject structure and add it to the kobject hierarchy
 375  * @kobj: pointer to the kobject to initialize
 376  * @ktype: pointer to the ktype for this kobject.
 377  * @parent: pointer to the parent of this kobject.
 378  * @fmt: the name of the kobject.
 379  *
 380  * This function combines the call to kobject_init() and
 381  * kobject_add().  The same type of error handling after a call to
 382  * kobject_add() and kobject lifetime rules are the same here.
 383  */
 384 int kobject_init_and_add(struct kobject *kobj, struct kobj_type *ktype,
 385                          struct kobject *parent, const char *fmt, ...)
 386 {
 387         va_list args;
 388         int retval;
 389
 390         kobject_init(kobj, ktype);
 391
 392         va_start(args, fmt);
 393         retval = kobject_add_varg(kobj, parent, fmt, args);
 394         va_end(args);
 395
 396         return retval;
 397 }
 398 EXPORT_SYMBOL_GPL(kobject_init_and_add);
 399
 400 /**
 401  * kobject_rename - change the name of an object
 402  * @kobj: object in question.
 403  * @new_name: object's new name
 404  */
 405 int kobject_rename(struct kobject *kobj, const char *new_name)
 406 {
 407         int error = 0;
 408         const char *devpath = NULL;
 409         char *devpath_string = NULL;
 410         char *envp[2];
 411
 412         kobj = kobject_get(kobj);
 413         if (!kobj)
 414                 return -EINVAL;
 415         if (!kobj->parent)
 416                 return -EINVAL;
 417
 418         /* see if this name is already in use */
 419         if (kobj->kset) {
 420                 struct kobject *temp_kobj;
 421                 temp_kobj = kset_find_obj(kobj->kset, new_name);
 422                 if (temp_kobj) {
 423                         printk(KERN_WARNING "kobject '%s' cannot be renamed "
 424                                "to '%s' as '%s' is already in existence.\n",
 425                                kobject_name(kobj), new_name, new_name);
 426                         kobject_put(temp_kobj);
 427                         return -EINVAL;
 428                 }
 429         }
 430
 431         devpath = kobject_get_path(kobj, GFP_KERNEL);
 432         if (!devpath) {
 433                 error = -ENOMEM;
 434                 goto out;
 435         }
 436         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 437         if (!devpath_string) {
 438                 error = -ENOMEM;
 439                 goto out;
 440         }
 441         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 442         envp[0] = devpath_string;
 443         envp[1] = NULL;
 444
 445         error = sysfs_rename_dir(kobj, new_name);
 446
 447         /* This function is mostly/only used for network interface.
 448          * Some hotplug package track interfaces by their name and
 449          * therefore want to know when the name is changed by the user. */
 450         if (!error)
 451                 kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 452
 453 out:
 454         kfree(devpath_string);
 455         kfree(devpath);
 456         kobject_put(kobj);
 457
 458         return error;
 459 }
 460
 461 /**
 462  * kobject_move - move object to another parent
 463  * @kobj: object in question.
 464  * @new_parent: object's new parent (can be NULL)
 465  */
 466 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 467 {
 468         int error;
 469         struct kobject *old_parent;
 470         const char *devpath = NULL;
 471         char *devpath_string = NULL;
 472         char *envp[2];
 473
 474         kobj = kobject_get(kobj);
 475         if (!kobj)
 476                 return -EINVAL;
 477         new_parent = kobject_get(new_parent);
 478         if (!new_parent) {
 479                 if (kobj->kset)
 480                         new_parent = kobject_get(&kobj->kset->kobj);
 481         }
 482         /* old object path */
 483         devpath = kobject_get_path(kobj, GFP_KERNEL);
 484         if (!devpath) {
 485                 error = -ENOMEM;
 486                 goto out;
 487         }
 488         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 489         if (!devpath_string) {
 490                 error = -ENOMEM;
 491                 goto out;
 492         }
 493         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 494         envp[0] = devpath_string;
 495         envp[1] = NULL;
 496         error = sysfs_move_dir(kobj, new_parent);
 497         if (error)
 498                 goto out;
 499         old_parent = kobj->parent;
 500         kobj->parent = new_parent;
 501         new_parent = NULL;
 502         kobject_put(old_parent);
 503         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 504 out:
 505         kobject_put(new_parent);
 506         kobject_put(kobj);
 507         kfree(devpath_string);
 508         kfree(devpath);
 509         return error;
 510 }
 511
 512 /**
 513  * kobject_del - unlink kobject from hierarchy.
 514  * @kobj: object.
 515  */
 516 void kobject_del(struct kobject *kobj)
 517 {
 518         if (!kobj)
 519                 return;
 520
 521         sysfs_remove_dir(kobj);
 522         kobj->state_in_sysfs = 0;
 523         kobj_kset_leave(kobj);
 524         kobject_put(kobj->parent);
 525         kobj->parent = NULL;
 526 }
 527
 528 /**
 529  * kobject_get - increment refcount for object.
 530  * @kobj: object.
 531  */
 532 struct kobject *kobject_get(struct kobject *kobj)
 533 {
 534         if (kobj)
 535                 kref_get(&kobj->kref);
 536         return kobj;
 537 }
 538
 539 /*
 540  * kobject_cleanup - free kobject resources.
 541  * @kobj: object to cleanup
 542  */
 543 static void kobject_cleanup(struct kobject *kobj)
 544 {
 545         struct kobj_type *t = get_ktype(kobj);
 546         const char *name = kobj->name;
 547
 548         pr_debug("kobject: '%s' (%p): %s\n",
 549                  kobject_name(kobj), kobj, __FUNCTION__);
 550
 551         if (t && !t->release)
 552                 pr_debug("kobject: '%s' (%p): does not have a release() "
 553                          "function, it is broken and must be fixed.\n",
 554                          kobject_name(kobj), kobj);
 555
 556         /* send "remove" if the caller did not do it but sent "add" */
 557         if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
 558                 pr_debug("kobject: '%s' (%p): auto cleanup 'remove' event\n",
 559                          kobject_name(kobj), kobj);
 560                 kobject_uevent(kobj, KOBJ_REMOVE);
 561         }
 562
 563         /* remove from sysfs if the caller did not do it */
 564         if (kobj->state_in_sysfs) {
 565                 pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n",
 566                          kobject_name(kobj), kobj);
 567                 kobject_del(kobj);
 568         }
 569
 570         if (t && t->release) {
 571                 pr_debug("kobject: '%s' (%p): calling ktype release\n",
 572                          kobject_name(kobj), kobj);
 573                 t->release(kobj);
 574         }
 575
 576         /* free name if we allocated it */
 577         if (name) {
 578                 pr_debug("kobject: '%s': free name\n", name);
 579                 kfree(name);
 580         }
 581 }
 582
 583 static void kobject_release(struct kref *kref)
 584 {
 585         kobject_cleanup(container_of(kref, struct kobject, kref));
 586 }
 587
 588 /**
 589  * kobject_put - decrement refcount for object.
 590  * @kobj: object.
 591  *
 592  * Decrement the refcount, and if 0, call kobject_cleanup().
 593  */
 594 void kobject_put(struct kobject *kobj)
 595 {
 596         if (kobj)
 597                 kref_put(&kobj->kref, kobject_release);
 598 }
 599
 600 static void dynamic_kobj_release(struct kobject *kobj)
 601 {
 602         pr_debug("kobject: (%p): %s\n", kobj, __FUNCTION__);
 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 kset 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                        __FUNCTION__, 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 list_head *entry;
 750         struct kobject *ret = NULL;
 751
 752         spin_lock(&kset->list_lock);
 753         list_for_each(entry, &kset->list) {
 754                 struct kobject *k = to_kobj(entry);
 755                 if (kobject_name(k) && !strcmp(kobject_name(k), name)) {
 756                         ret = kobject_get(k);
 757                         break;
 758                 }
 759         }
 760         spin_unlock(&kset->list_lock);
 761         return ret;
 762 }
 763
 764 static void kset_release(struct kobject *kobj)
 765 {
 766         struct kset *kset = container_of(kobj, struct kset, kobj);
 767         pr_debug("kobject: '%s' (%p): %s\n",
 768                  kobject_name(kobj), kobj, __FUNCTION__);
 769         kfree(kset);
 770 }
 771
 772 static struct kobj_type kset_ktype = {
 773         .sysfs_ops      = &kobj_sysfs_ops,
 774         .release = kset_release,
 775 };
 776
 777 /**
 778  * kset_create - create a struct kset dynamically
 779  *
 780  * @name: the name for the kset
 781  * @uevent_ops: a struct kset_uevent_ops for the kset
 782  * @parent_kobj: the parent kobject of this kset, if any.
 783  *
 784  * This function creates a kset structure dynamically.  This structure can
 785  * then be registered with the system and show up in sysfs with a call to
 786  * kset_register().  When you are finished with this structure, if
 787  * kset_register() has been called, call kset_unregister() and the
 788  * structure will be dynamically freed when it is no longer being used.
 789  *
 790  * If the kset was not able to be created, NULL will be returned.
 791  */
 792 static struct kset *kset_create(const char *name,
 793                                 struct kset_uevent_ops *uevent_ops,
 794                                 struct kobject *parent_kobj)
 795 {
 796         struct kset *kset;
 797
 798         kset = kzalloc(sizeof(*kset), GFP_KERNEL);
 799         if (!kset)
 800                 return NULL;
 801         kobject_set_name(&kset->kobj, name);
 802         kset->uevent_ops = uevent_ops;
 803         kset->kobj.parent = parent_kobj;
 804
 805         /*
 806          * The kobject of this kset will have a type of kset_ktype and belong to
 807          * no kset itself.  That way we can properly free it when it is
 808          * finished being used.
 809          */
 810         kset->kobj.ktype = &kset_ktype;
 811         kset->kobj.kset = NULL;
 812
 813         return kset;
 814 }
 815
 816 /**
 817  * kset_create_and_add - create a struct kset dynamically and add it to sysfs
 818  *
 819  * @name: the name for the kset
 820  * @uevent_ops: a struct kset_uevent_ops for the kset
 821  * @parent_kobj: the parent kobject of this kset, if any.
 822  *
 823  * This function creates a kset structure dynamically and registers it
 824  * with sysfs.  When you are finished with this structure, call
 825  * kset_unregister() and the structure will be dynamically freed when it
 826  * is no longer being used.
 827  *
 828  * If the kset was not able to be created, NULL will be returned.
 829  */
 830 struct kset *kset_create_and_add(const char *name,
 831                                  struct kset_uevent_ops *uevent_ops,
 832                                  struct kobject *parent_kobj)
 833 {
 834         struct kset *kset;
 835         int error;
 836
 837         kset = kset_create(name, uevent_ops, parent_kobj);
 838         if (!kset)
 839                 return NULL;
 840         error = kset_register(kset);
 841         if (error) {
 842                 kfree(kset);
 843                 return NULL;
 844         }
 845         return kset;
 846 }
 847 EXPORT_SYMBOL_GPL(kset_create_and_add);
 848
 849 EXPORT_SYMBOL(kobject_get);
 850 EXPORT_SYMBOL(kobject_put);
 851 EXPORT_SYMBOL(kobject_del);
 852
 853 EXPORT_SYMBOL(kset_register);
 854 EXPORT_SYMBOL(kset_unregister);