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