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