linux/lib/kobject.c
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   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 */
  30static 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
  47static 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
  61static 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
  79static 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 */
 104char *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}
 119EXPORT_SYMBOL_GPL(kobject_get_path);
 120
 121/* add the kobject to its kset's list */
 122static 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 */
 134static 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
 145static 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
 158static 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 */
 215static int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
 216                                  va_list vargs)
 217{
 218        const char *old_name = kobj->name;
 219        char *s;
 220
 221        kobj->name = kvasprintf(GFP_KERNEL, fmt, vargs);
 222        if (!kobj->name)
 223                return -ENOMEM;
 224
 225        /* ewww... some of these buggers have '/' in the name ... */
 226        while ((s = strchr(kobj->name, '/')))
 227                s[0] = '!';
 228
 229        kfree(old_name);
 230        return 0;
 231}
 232
 233/**
 234 * kobject_set_name - Set the name of a kobject
 235 * @kobj: struct kobject to set the name of
 236 * @fmt: format string used to build the name
 237 *
 238 * This sets the name of the kobject.  If you have already added the
 239 * kobject to the system, you must call kobject_rename() in order to
 240 * change the name of the kobject.
 241 */
 242int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
 243{
 244        va_list vargs;
 245        int retval;
 246
 247        va_start(vargs, fmt);
 248        retval = kobject_set_name_vargs(kobj, fmt, vargs);
 249        va_end(vargs);
 250
 251        return retval;
 252}
 253EXPORT_SYMBOL(kobject_set_name);
 254
 255/**
 256 * kobject_init - initialize a kobject structure
 257 * @kobj: pointer to the kobject to initialize
 258 * @ktype: pointer to the ktype for this kobject.
 259 *
 260 * This function will properly initialize a kobject such that it can then
 261 * be passed to the kobject_add() call.
 262 *
 263 * After this function is called, the kobject MUST be cleaned up by a call
 264 * to kobject_put(), not by a call to kfree directly to ensure that all of
 265 * the memory is cleaned up properly.
 266 */
 267void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
 268{
 269        char *err_str;
 270
 271        if (!kobj) {
 272                err_str = "invalid kobject pointer!";
 273                goto error;
 274        }
 275        if (!ktype) {
 276                err_str = "must have a ktype to be initialized properly!\n";
 277                goto error;
 278        }
 279        if (kobj->state_initialized) {
 280                /* do not error out as sometimes we can recover */
 281                printk(KERN_ERR "kobject (%p): tried to init an initialized "
 282                       "object, something is seriously wrong.\n", kobj);
 283                dump_stack();
 284        }
 285
 286        kobject_init_internal(kobj);
 287        kobj->ktype = ktype;
 288        return;
 289
 290error:
 291        printk(KERN_ERR "kobject (%p): %s\n", kobj, err_str);
 292        dump_stack();
 293}
 294EXPORT_SYMBOL(kobject_init);
 295
 296static int kobject_add_varg(struct kobject *kobj, struct kobject *parent,
 297                            const char *fmt, va_list vargs)
 298{
 299        int retval;
 300
 301        retval = kobject_set_name_vargs(kobj, fmt, vargs);
 302        if (retval) {
 303                printk(KERN_ERR "kobject: can not set name properly!\n");
 304                return retval;
 305        }
 306        kobj->parent = parent;
 307        return kobject_add_internal(kobj);
 308}
 309
 310/**
 311 * kobject_add - the main kobject add function
 312 * @kobj: the kobject to add
 313 * @parent: pointer to the parent of the kobject.
 314 * @fmt: format to name the kobject with.
 315 *
 316 * The kobject name is set and added to the kobject hierarchy in this
 317 * function.
 318 *
 319 * If @parent is set, then the parent of the @kobj will be set to it.
 320 * If @parent is NULL, then the parent of the @kobj will be set to the
 321 * kobject associted with the kset assigned to this kobject.  If no kset
 322 * is assigned to the kobject, then the kobject will be located in the
 323 * root of the sysfs tree.
 324 *
 325 * If this function returns an error, kobject_put() must be called to
 326 * properly clean up the memory associated with the object.
 327 * Under no instance should the kobject that is passed to this function
 328 * be directly freed with a call to kfree(), that can leak memory.
 329 *
 330 * Note, no "add" uevent will be created with this call, the caller should set
 331 * up all of the necessary sysfs files for the object and then call
 332 * kobject_uevent() with the UEVENT_ADD parameter to ensure that
 333 * userspace is properly notified of this kobject's creation.
 334 */
 335int kobject_add(struct kobject *kobj, struct kobject *parent,
 336                const char *fmt, ...)
 337{
 338        va_list args;
 339        int retval;
 340
 341        if (!kobj)
 342                return -EINVAL;
 343
 344        if (!kobj->state_initialized) {
 345                printk(KERN_ERR "kobject '%s' (%p): tried to add an "
 346                       "uninitialized object, something is seriously wrong.\n",
 347                       kobject_name(kobj), kobj);
 348                dump_stack();
 349                return -EINVAL;
 350        }
 351        va_start(args, fmt);
 352        retval = kobject_add_varg(kobj, parent, fmt, args);
 353        va_end(args);
 354
 355        return retval;
 356}
 357EXPORT_SYMBOL(kobject_add);
 358
 359/**
 360 * kobject_init_and_add - initialize a kobject structure and add it to the kobject hierarchy
 361 * @kobj: pointer to the kobject to initialize
 362 * @ktype: pointer to the ktype for this kobject.
 363 * @parent: pointer to the parent of this kobject.
 364 * @fmt: the name of the kobject.
 365 *
 366 * This function combines the call to kobject_init() and
 367 * kobject_add().  The same type of error handling after a call to
 368 * kobject_add() and kobject lifetime rules are the same here.
 369 */
 370int kobject_init_and_add(struct kobject *kobj, struct kobj_type *ktype,
 371                         struct kobject *parent, const char *fmt, ...)
 372{
 373        va_list args;
 374        int retval;
 375
 376        kobject_init(kobj, ktype);
 377
 378        va_start(args, fmt);
 379        retval = kobject_add_varg(kobj, parent, fmt, args);
 380        va_end(args);
 381
 382        return retval;
 383}
 384EXPORT_SYMBOL_GPL(kobject_init_and_add);
 385
 386/**
 387 * kobject_rename - change the name of an object
 388 * @kobj: object in question.
 389 * @new_name: object's new name
 390 */
 391int kobject_rename(struct kobject *kobj, const char *new_name)
 392{
 393        int error = 0;
 394        const char *devpath = NULL;
 395        char *devpath_string = NULL;
 396        char *envp[2];
 397
 398        kobj = kobject_get(kobj);
 399        if (!kobj)
 400                return -EINVAL;
 401        if (!kobj->parent)
 402                return -EINVAL;
 403
 404        /* see if this name is already in use */
 405        if (kobj->kset) {
 406                struct kobject *temp_kobj;
 407                temp_kobj = kset_find_obj(kobj->kset, new_name);
 408                if (temp_kobj) {
 409                        printk(KERN_WARNING "kobject '%s' cannot be renamed "
 410                               "to '%s' as '%s' is already in existence.\n",
 411                               kobject_name(kobj), new_name, new_name);
 412                        kobject_put(temp_kobj);
 413                        return -EINVAL;
 414                }
 415        }
 416
 417        devpath = kobject_get_path(kobj, GFP_KERNEL);
 418        if (!devpath) {
 419                error = -ENOMEM;
 420                goto out;
 421        }
 422        devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 423        if (!devpath_string) {
 424                error = -ENOMEM;
 425                goto out;
 426        }
 427        sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 428        envp[0] = devpath_string;
 429        envp[1] = NULL;
 430
 431        error = sysfs_rename_dir(kobj, new_name);
 432
 433        /* This function is mostly/only used for network interface.
 434         * Some hotplug package track interfaces by their name and
 435         * therefore want to know when the name is changed by the user. */
 436        if (!error)
 437                kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 438
 439out:
 440        kfree(devpath_string);
 441        kfree(devpath);
 442        kobject_put(kobj);
 443
 444        return error;
 445}
 446EXPORT_SYMBOL_GPL(kobject_rename);
 447
 448/**
 449 * kobject_move - move object to another parent
 450 * @kobj: object in question.
 451 * @new_parent: object's new parent (can be NULL)
 452 */
 453int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 454{
 455        int error;
 456        struct kobject *old_parent;
 457        const char *devpath = NULL;
 458        char *devpath_string = NULL;
 459        char *envp[2];
 460
 461        kobj = kobject_get(kobj);
 462        if (!kobj)
 463                return -EINVAL;
 464        new_parent = kobject_get(new_parent);
 465        if (!new_parent) {
 466                if (kobj->kset)
 467                        new_parent = kobject_get(&kobj->kset->kobj);
 468        }
 469        /* old object path */
 470        devpath = kobject_get_path(kobj, GFP_KERNEL);
 471        if (!devpath) {
 472                error = -ENOMEM;
 473                goto out;
 474        }
 475        devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 476        if (!devpath_string) {
 477                error = -ENOMEM;
 478                goto out;
 479        }
 480        sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 481        envp[0] = devpath_string;
 482        envp[1] = NULL;
 483        error = sysfs_move_dir(kobj, new_parent);
 484        if (error)
 485                goto out;
 486        old_parent = kobj->parent;
 487        kobj->parent = new_parent;
 488        new_parent = NULL;
 489        kobject_put(old_parent);
 490        kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 491out:
 492        kobject_put(new_parent);
 493        kobject_put(kobj);
 494        kfree(devpath_string);
 495        kfree(devpath);
 496        return error;
 497}
 498
 499/**
 500 * kobject_del - unlink kobject from hierarchy.
 501 * @kobj: object.
 502 */
 503void kobject_del(struct kobject *kobj)
 504{
 505        if (!kobj)
 506                return;
 507
 508        sysfs_remove_dir(kobj);
 509        kobj->state_in_sysfs = 0;
 510        kobj_kset_leave(kobj);
 511        kobject_put(kobj->parent);
 512        kobj->parent = NULL;
 513}
 514
 515/**
 516 * kobject_get - increment refcount for object.
 517 * @kobj: object.
 518 */
 519struct kobject *kobject_get(struct kobject *kobj)
 520{
 521        if (kobj)
 522                kref_get(&kobj->kref);
 523        return kobj;
 524}
 525
 526/*
 527 * kobject_cleanup - free kobject resources.
 528 * @kobj: object to cleanup
 529 */
 530static void kobject_cleanup(struct kobject *kobj)
 531{
 532        struct kobj_type *t = get_ktype(kobj);
 533        const char *name = kobj->name;
 534
 535        pr_debug("kobject: '%s' (%p): %s\n",
 536                 kobject_name(kobj), kobj, __func__);
 537
 538        if (t && !t->release)
 539                pr_debug("kobject: '%s' (%p): does not have a release() "
 540                         "function, it is broken and must be fixed.\n",
 541                         kobject_name(kobj), kobj);
 542
 543        /* send "remove" if the caller did not do it but sent "add" */
 544        if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
 545                pr_debug("kobject: '%s' (%p): auto cleanup 'remove' event\n",
 546                         kobject_name(kobj), kobj);
 547                kobject_uevent(kobj, KOBJ_REMOVE);
 548        }
 549
 550        /* remove from sysfs if the caller did not do it */
 551        if (kobj->state_in_sysfs) {
 552                pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n",
 553                         kobject_name(kobj), kobj);
 554                kobject_del(kobj);
 555        }
 556
 557        if (t && t->release) {
 558                pr_debug("kobject: '%s' (%p): calling ktype release\n",
 559                         kobject_name(kobj), kobj);
 560                t->release(kobj);
 561        }
 562
 563        /* free name if we allocated it */
 564        if (name) {
 565                pr_debug("kobject: '%s': free name\n", name);
 566                kfree(name);
 567        }
 568}
 569
 570static void kobject_release(struct kref *kref)
 571{
 572        kobject_cleanup(container_of(kref, struct kobject, kref));
 573}
 574
 575/**
 576 * kobject_put - decrement refcount for object.
 577 * @kobj: object.
 578 *
 579 * Decrement the refcount, and if 0, call kobject_cleanup().
 580 */
 581void kobject_put(struct kobject *kobj)
 582{
 583        if (kobj) {
 584                if (!kobj->state_initialized)
 585                        WARN(1, KERN_WARNING "kobject: '%s' (%p): is not "
 586                               "initialized, yet kobject_put() is being "
 587                               "called.\n", kobject_name(kobj), kobj);
 588                kref_put(&kobj->kref, kobject_release);
 589        }
 590}
 591
 592static void dynamic_kobj_release(struct kobject *kobj)
 593{
 594        pr_debug("kobject: (%p): %s\n", kobj, __func__);
 595        kfree(kobj);
 596}
 597
 598static struct kobj_type dynamic_kobj_ktype = {
 599        .release        = dynamic_kobj_release,
 600        .sysfs_ops      = &kobj_sysfs_ops,
 601};
 602
 603/**
 604 * kobject_create - create a struct kobject dynamically
 605 *
 606 * This function creates a kobject structure dynamically and sets it up
 607 * to be a "dynamic" kobject with a default release function set up.
 608 *
 609 * If the kobject was not able to be created, NULL will be returned.
 610 * The kobject structure returned from here must be cleaned up with a
 611 * call to kobject_put() and not kfree(), as kobject_init() has
 612 * already been called on this structure.
 613 */
 614struct kobject *kobject_create(void)
 615{
 616        struct kobject *kobj;
 617
 618        kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
 619        if (!kobj)
 620                return NULL;
 621
 622        kobject_init(kobj, &dynamic_kobj_ktype);
 623        return kobj;
 624}
 625
 626/**
 627 * kobject_create_and_add - create a struct kobject dynamically and register it with sysfs
 628 *
 629 * @name: the name for the kset
 630 * @parent: the parent kobject of this kobject, if any.
 631 *
 632 * This function creates a kobject structure dynamically and registers it
 633 * with sysfs.  When you are finished with this structure, call
 634 * kobject_put() and the structure will be dynamically freed when
 635 * it is no longer being used.
 636 *
 637 * If the kobject was not able to be created, NULL will be returned.
 638 */
 639struct kobject *kobject_create_and_add(const char *name, struct kobject *parent)
 640{
 641        struct kobject *kobj;
 642        int retval;
 643
 644        kobj = kobject_create();
 645        if (!kobj)
 646                return NULL;
 647
 648        retval = kobject_add(kobj, parent, "%s", name);
 649        if (retval) {
 650                printk(KERN_WARNING "%s: kobject_add error: %d\n",
 651                       __func__, retval);
 652                kobject_put(kobj);
 653                kobj = NULL;
 654        }
 655        return kobj;
 656}
 657EXPORT_SYMBOL_GPL(kobject_create_and_add);
 658
 659/**
 660 * kset_init - initialize a kset for use
 661 * @k: kset
 662 */
 663void kset_init(struct kset *k)
 664{
 665        kobject_init_internal(&k->kobj);
 666        INIT_LIST_HEAD(&k->list);
 667        spin_lock_init(&k->list_lock);
 668}
 669
 670/* default kobject attribute operations */
 671static ssize_t kobj_attr_show(struct kobject *kobj, struct attribute *attr,
 672                              char *buf)
 673{
 674        struct kobj_attribute *kattr;
 675        ssize_t ret = -EIO;
 676
 677        kattr = container_of(attr, struct kobj_attribute, attr);
 678        if (kattr->show)
 679                ret = kattr->show(kobj, kattr, buf);
 680        return ret;
 681}
 682
 683static ssize_t kobj_attr_store(struct kobject *kobj, struct attribute *attr,
 684                               const char *buf, size_t count)
 685{
 686        struct kobj_attribute *kattr;
 687        ssize_t ret = -EIO;
 688
 689        kattr = container_of(attr, struct kobj_attribute, attr);
 690        if (kattr->store)
 691                ret = kattr->store(kobj, kattr, buf, count);
 692        return ret;
 693}
 694
 695struct sysfs_ops kobj_sysfs_ops = {
 696        .show   = kobj_attr_show,
 697        .store  = kobj_attr_store,
 698};
 699
 700/**
 701 * kset_register - initialize and add a kset.
 702 * @k: kset.
 703 */
 704int kset_register(struct kset *k)
 705{
 706        int err;
 707
 708        if (!k)
 709                return -EINVAL;
 710
 711        kset_init(k);
 712        err = kobject_add_internal(&k->kobj);
 713        if (err)
 714                return err;
 715        kobject_uevent(&k->kobj, KOBJ_ADD);
 716        return 0;
 717}
 718
 719/**
 720 * kset_unregister - remove a kset.
 721 * @k: kset.
 722 */
 723void kset_unregister(struct kset *k)
 724{
 725        if (!k)
 726                return;
 727        kobject_put(&k->kobj);
 728}
 729
 730/**
 731 * kset_find_obj - search for object in kset.
 732 * @kset: kset we're looking in.
 733 * @name: object's name.
 734 *
 735 * Lock kset via @kset->subsys, and iterate over @kset->list,
 736 * looking for a matching kobject. If matching object is found
 737 * take a reference and return the object.
 738 */
 739struct kobject *kset_find_obj(struct kset *kset, const char *name)
 740{
 741        struct kobject *k;
 742        struct kobject *ret = NULL;
 743
 744        spin_lock(&kset->list_lock);
 745        list_for_each_entry(k, &kset->list, entry) {
 746                if (kobject_name(k) && !strcmp(kobject_name(k), name)) {
 747                        ret = kobject_get(k);
 748                        break;
 749                }
 750        }
 751        spin_unlock(&kset->list_lock);
 752        return ret;
 753}
 754
 755static void kset_release(struct kobject *kobj)
 756{
 757        struct kset *kset = container_of(kobj, struct kset, kobj);
 758        pr_debug("kobject: '%s' (%p): %s\n",
 759                 kobject_name(kobj), kobj, __func__);
 760        kfree(kset);
 761}
 762
 763static struct kobj_type kset_ktype = {
 764        .sysfs_ops      = &kobj_sysfs_ops,
 765        .release = kset_release,
 766};
 767
 768/**
 769 * kset_create - create a struct kset dynamically
 770 *
 771 * @name: the name for the kset
 772 * @uevent_ops: a struct kset_uevent_ops for the kset
 773 * @parent_kobj: the parent kobject of this kset, if any.
 774 *
 775 * This function creates a kset structure dynamically.  This structure can
 776 * then be registered with the system and show up in sysfs with a call to
 777 * kset_register().  When you are finished with this structure, if
 778 * kset_register() has been called, call kset_unregister() and the
 779 * structure will be dynamically freed when it is no longer being used.
 780 *
 781 * If the kset was not able to be created, NULL will be returned.
 782 */
 783static struct kset *kset_create(const char *name,
 784                                struct kset_uevent_ops *uevent_ops,
 785                                struct kobject *parent_kobj)
 786{
 787        struct kset *kset;
 788
 789        kset = kzalloc(sizeof(*kset), GFP_KERNEL);
 790        if (!kset)
 791                return NULL;
 792        kobject_set_name(&kset->kobj, name);
 793        kset->uevent_ops = uevent_ops;
 794        kset->kobj.parent = parent_kobj;
 795
 796        /*
 797         * The kobject of this kset will have a type of kset_ktype and belong to
 798         * no kset itself.  That way we can properly free it when it is
 799         * finished being used.
 800         */
 801        kset->kobj.ktype = &kset_ktype;
 802        kset->kobj.kset = NULL;
 803
 804        return kset;
 805}
 806
 807/**
 808 * kset_create_and_add - create a struct kset dynamically and add it to sysfs
 809 *
 810 * @name: the name for the kset
 811 * @uevent_ops: a struct kset_uevent_ops for the kset
 812 * @parent_kobj: the parent kobject of this kset, if any.
 813 *
 814 * This function creates a kset structure dynamically and registers it
 815 * with sysfs.  When you are finished with this structure, call
 816 * kset_unregister() and the structure will be dynamically freed when it
 817 * is no longer being used.
 818 *
 819 * If the kset was not able to be created, NULL will be returned.
 820 */
 821struct kset *kset_create_and_add(const char *name,
 822                                 struct kset_uevent_ops *uevent_ops,
 823                                 struct kobject *parent_kobj)
 824{
 825        struct kset *kset;
 826        int error;
 827
 828        kset = kset_create(name, uevent_ops, parent_kobj);
 829        if (!kset)
 830                return NULL;
 831        error = kset_register(kset);
 832        if (error) {
 833                kfree(kset);
 834                return NULL;
 835        }
 836        return kset;
 837}
 838EXPORT_SYMBOL_GPL(kset_create_and_add);
 839
 840EXPORT_SYMBOL(kobject_get);
 841EXPORT_SYMBOL(kobject_put);
 842EXPORT_SYMBOL(kobject_del);
 843
 844EXPORT_SYMBOL(kset_register);
 845EXPORT_SYMBOL(kset_unregister);
 846
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