lib/kobject.c

   1 /*
   2  * kobject.c - library routines for handling generic kernel objects
   3  *
   4  * Copyright (c) 2002-2003 Patrick Mochel <mochel@osdl.org>
   5  * Copyright (c) 2006-2007 Greg Kroah-Hartman <greg@kroah.com>
   6  * Copyright (c) 2006-2007 Novell Inc.
   7  *
   8  * This file is released under the GPLv2.
   9  *
  10  *
  11  * Please see the file Documentation/kobject.txt for critical information
  12  * about using the kobject interface.
  13  */
  14
  15 #include <linux/kobject.h>
  16 #include <linux/string.h>
  17 #include <linux/module.h>
  18 #include <linux/stat.h>
  19 #include <linux/slab.h>
  20
  21 /*
  22  * populate_dir - populate directory with attributes.
  23  * @kobj: object we're working on.
  24  *
  25  * Most subsystems have a set of default attributes that are associated
  26  * with an object that registers with them.  This is a helper called during
  27  * object registration that loops through the default attributes of the
  28  * subsystem and creates attributes files for them in sysfs.
  29  */
  30 static int populate_dir(struct kobject *kobj)
  31 {
  32         struct kobj_type *t = get_ktype(kobj);
  33         struct attribute *attr;
  34         int error = 0;
  35         int i;
  36
  37         if (t && t->default_attrs) {
  38                 for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
  39                         error = sysfs_create_file(kobj, attr);
  40                         if (error)
  41                                 break;
  42                 }
  43         }
  44         return error;
  45 }
  46
  47 static int create_dir(struct kobject *kobj)
  48 {
  49         int error = 0;
  50         if (kobject_name(kobj)) {
  51                 error = sysfs_create_dir(kobj);
  52                 if (!error) {
  53                         error = populate_dir(kobj);
  54                         if (error)
  55                                 sysfs_remove_dir(kobj);
  56                 }
  57         }
  58         return error;
  59 }
  60
  61 static int get_kobj_path_length(struct kobject *kobj)
  62 {
  63         int length = 1;
  64         struct kobject *parent = kobj;
  65
  66         /* walk up the ancestors until we hit the one pointing to the
  67          * root.
  68          * Add 1 to strlen for leading '/' of each level.
  69          */
  70         do {
  71                 if (kobject_name(parent) == NULL)
  72                         return 0;
  73                 length += strlen(kobject_name(parent)) + 1;
  74                 parent = parent->parent;
  75         } while (parent);
  76         return length;
  77 }
  78
  79 static void fill_kobj_path(struct kobject *kobj, char *path, int length)
  80 {
  81         struct kobject *parent;
  82
  83         --length;
  84         for (parent = kobj; parent; parent = parent->parent) {
  85                 int cur = strlen(kobject_name(parent));
  86                 /* back up enough to print this name with '/' */
  87                 length -= cur;
  88                 strncpy(path + length, kobject_name(parent), cur);
  89                 *(path + --length) = '/';
  90         }
  91
  92         pr_debug("kobject: '%s' (%p): %s: path = '%s'\n", kobject_name(kobj),
  93                  kobj, __func__, path);
  94 }
  95
  96 /**
  97  * kobject_get_path - generate and return the path associated with a given kobj and kset pair.
  98  *
  99  * @kobj:       kobject in question, with which to build the path
 100  * @gfp_mask:   the allocation type used to allocate the path
 101  *
 102  * The result must be freed by the caller with kfree().
 103  */
 104 char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
 105 {
 106         char *path;
 107         int len;
 108
 109         len = get_kobj_path_length(kobj);
 110         if (len == 0)
 111                 return NULL;
 112         path = kzalloc(len, gfp_mask);
 113         if (!path)
 114                 return NULL;
 115         fill_kobj_path(kobj, path, len);
 116
 117         return path;
 118 }
 119 EXPORT_SYMBOL_GPL(kobject_get_path);
 120
 121 /* add the kobject to its kset's list */
 122 static void kobj_kset_join(struct kobject *kobj)
 123 {
 124         if (!kobj->kset)
 125                 return;
 126
 127         kset_get(kobj->kset);
 128         spin_lock(&kobj->kset->list_lock);
 129         list_add_tail(&kobj->entry, &kobj->kset->list);
 130         spin_unlock(&kobj->kset->list_lock);
 131 }
 132
 133 /* remove the kobject from its kset's list */
 134 static void kobj_kset_leave(struct kobject *kobj)
 135 {
 136         if (!kobj->kset)
 137                 return;
 138
 139         spin_lock(&kobj->kset->list_lock);
 140         list_del_init(&kobj->entry);
 141         spin_unlock(&kobj->kset->list_lock);
 142         kset_put(kobj->kset);
 143 }
 144
 145 static void kobject_init_internal(struct kobject *kobj)
 146 {
 147         if (!kobj)
 148                 return;
 149         kref_init(&kobj->kref);
 150         INIT_LIST_HEAD(&kobj->entry);
 151         kobj->state_in_sysfs = 0;
 152         kobj->state_add_uevent_sent = 0;
 153         kobj->state_remove_uevent_sent = 0;
 154         kobj->state_initialized = 1;
 155 }
 156
 157
 158 static int kobject_add_internal(struct kobject *kobj)
 159 {
 160         int error = 0;
 161         struct kobject *parent;
 162
 163         if (!kobj)
 164                 return -ENOENT;
 165
 166         if (!kobj->name || !kobj->name[0]) {
 167                 WARN(1, "kobject: (%p): attempted to be registered with empty "
 168                          "name!\n", kobj);
 169                 return -EINVAL;
 170         }
 171
 172         parent = kobject_get(kobj->parent);
 173
 174         /* join kset if set, use it as parent if we do not already have one */
 175         if (kobj->kset) {
 176                 if (!parent)
 177                         parent = kobject_get(&kobj->kset->kobj);
 178                 kobj_kset_join(kobj);
 179                 kobj->parent = parent;
 180         }
 181
 182         pr_debug("kobject: '%s' (%p): %s: parent: '%s', set: '%s'\n",
 183                  kobject_name(kobj), kobj, __func__,
 184                  parent ? kobject_name(parent) : "<NULL>",
 185                  kobj->kset ? kobject_name(&kobj->kset->kobj) : "<NULL>");
 186
 187         error = create_dir(kobj);
 188         if (error) {
 189                 kobj_kset_leave(kobj);
 190                 kobject_put(parent);
 191                 kobj->parent = NULL;
 192
 193                 /* be noisy on error issues */
 194                 if (error == -EEXIST)
 195                         printk(KERN_ERR "%s failed for %s with "
 196                                "-EEXIST, don't try to register things with "
 197                                "the same name in the same directory.\n",
 198                                __func__, kobject_name(kobj));
 199                 else
 200                         printk(KERN_ERR "%s failed for %s (%d)\n",
 201                                __func__, kobject_name(kobj), error);
 202                 dump_stack();
 203         } else
 204                 kobj->state_in_sysfs = 1;
 205
 206         return error;
 207 }
 208
 209 /**
 210  * kobject_set_name_vargs - Set the name of an kobject
 211  * @kobj: struct kobject to set the name of
 212  * @fmt: format string used to build the name
 213  * @vargs: vargs to format the string.
 214  */
 215 static 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  */
 242 int 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 }
 253 EXPORT_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  */
 267 void 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
 290 error:
 291         printk(KERN_ERR "kobject (%p): %s\n", kobj, err_str);
 292         dump_stack();
 293 }
 294 EXPORT_SYMBOL(kobject_init);
 295
 296 static 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  */
 335 int 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 }
 357 EXPORT_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  */
 370 int 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 }
 384 EXPORT_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  */
 391 int 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
 439 out:
 440         kfree(devpath_string);
 441         kfree(devpath);
 442         kobject_put(kobj);
 443
 444         return error;
 445 }
 446 EXPORT_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  */
 453 int 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);
 491 out:
 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  */
 503 void 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  */
 519 struct 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  */
 530 static 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
 570 static 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  */
 581 void 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
 592 static void dynamic_kobj_release(struct kobject *kobj)
 593 {
 594         pr_debug("kobject: (%p): %s\n", kobj, __func__);
 595         kfree(kobj);
 596 }
 597
 598 static 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  */
 614 struct 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  */
 639 struct 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 }
 657 EXPORT_SYMBOL_GPL(kobject_create_and_add);
 658
 659 /**
 660  * kset_init - initialize a kset for use
 661  * @k: kset
 662  */
 663 void 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 */
 671 static 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
 683 static 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
 695 struct 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  */
 704 int 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  */
 723 void 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  */
 739 struct 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
 755 static 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
 763 static 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  */
 783 static 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  */
 821 struct 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 }
 838 EXPORT_SYMBOL_GPL(kset_create_and_add);
 839
 840 EXPORT_SYMBOL(kobject_get);
 841 EXPORT_SYMBOL(kobject_put);
 842 EXPORT_SYMBOL(kobject_del);
 843
 844 EXPORT_SYMBOL(kset_register);
 845 EXPORT_SYMBOL(kset_unregister);