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
  26  *      are associated with an object that registers with them.
  27  *      This is a helper called during object registration that
  28  *      loops through the default attributes of the subsystem
  29  *      and creates attributes files for them in sysfs.
  30  *
  31  */
  32
  33 static int populate_dir(struct kobject * kobj)
  34 {
  35         struct kobj_type * t = get_ktype(kobj);
  36         struct attribute * attr;
  37         int error = 0;
  38         int i;
  39
  40         if (t && t->default_attrs) {
  41                 for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
  42                         if ((error = sysfs_create_file(kobj,attr)))
  43                                 break;
  44                 }
  45         }
  46         return error;
  47 }
  48
  49 static int create_dir(struct kobject * kobj)
  50 {
  51         int error = 0;
  52         if (kobject_name(kobj)) {
  53                 error = sysfs_create_dir(kobj);
  54                 if (!error) {
  55                         if ((error = populate_dir(kobj)))
  56                                 sysfs_remove_dir(kobj);
  57                 }
  58         }
  59         return error;
  60 }
  61
  62 static inline struct kobject * to_kobj(struct list_head * entry)
  63 {
  64         return container_of(entry,struct kobject,entry);
  65 }
  66
  67 static int get_kobj_path_length(struct kobject *kobj)
  68 {
  69         int length = 1;
  70         struct kobject * parent = kobj;
  71
  72         /* walk up the ancestors until we hit the one pointing to the
  73          * root.
  74          * Add 1 to strlen for leading '/' of each level.
  75          */
  76         do {
  77                 if (kobject_name(parent) == NULL)
  78                         return 0;
  79                 length += strlen(kobject_name(parent)) + 1;
  80                 parent = parent->parent;
  81         } while (parent);
  82         return length;
  83 }
  84
  85 static void fill_kobj_path(struct kobject *kobj, char *path, int length)
  86 {
  87         struct kobject * parent;
  88
  89         --length;
  90         for (parent = kobj; parent; parent = parent->parent) {
  91                 int cur = strlen(kobject_name(parent));
  92                 /* back up enough to print this name with '/' */
  93                 length -= cur;
  94                 strncpy (path + length, kobject_name(parent), cur);
  95                 *(path + --length) = '/';
  96         }
  97
  98         pr_debug("%s: path = '%s'\n",__FUNCTION__,path);
  99 }
 100
 101 /**
 102  * kobject_get_path - generate and return the path associated with a given kobj and kset pair.
 103  *
 104  * @kobj:       kobject in question, with which to build the path
 105  * @gfp_mask:   the allocation type used to allocate the path
 106  *
 107  * The result must be freed by the caller with kfree().
 108  */
 109 char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
 110 {
 111         char *path;
 112         int len;
 113
 114         len = get_kobj_path_length(kobj);
 115         if (len == 0)
 116                 return NULL;
 117         path = kzalloc(len, gfp_mask);
 118         if (!path)
 119                 return NULL;
 120         fill_kobj_path(kobj, path, len);
 121
 122         return path;
 123 }
 124 EXPORT_SYMBOL_GPL(kobject_get_path);
 125
 126 /**
 127  *      kobject_init - initialize object.
 128  *      @kobj:  object in question.
 129  */
 130 void kobject_init(struct kobject * kobj)
 131 {
 132         if (!kobj)
 133                 return;
 134         kref_init(&kobj->kref);
 135         INIT_LIST_HEAD(&kobj->entry);
 136         kobj->kset = kset_get(kobj->kset);
 137 }
 138
 139
 140 /**
 141  *      unlink - remove kobject from kset list.
 142  *      @kobj:  kobject.
 143  *
 144  *      Remove the kobject from the kset list and decrement
 145  *      its parent's refcount.
 146  *      This is separated out, so we can use it in both
 147  *      kobject_del() and kobject_add() on error.
 148  */
 149
 150 static void unlink(struct kobject * kobj)
 151 {
 152         if (kobj->kset) {
 153                 spin_lock(&kobj->kset->list_lock);
 154                 list_del_init(&kobj->entry);
 155                 spin_unlock(&kobj->kset->list_lock);
 156         }
 157         kobject_put(kobj);
 158 }
 159
 160 /**
 161  *      kobject_add - add an object to the hierarchy.
 162  *      @kobj:  object.
 163  */
 164
 165 int kobject_add(struct kobject * kobj)
 166 {
 167         int error = 0;
 168         struct kobject * parent;
 169
 170         if (!(kobj = kobject_get(kobj)))
 171                 return -ENOENT;
 172         if (!kobj->k_name)
 173                 kobject_set_name(kobj, "NO_NAME");
 174         if (!*kobj->k_name) {
 175                 pr_debug("kobject attempted to be registered with no name!\n");
 176                 WARN_ON(1);
 177                 kobject_put(kobj);
 178                 return -EINVAL;
 179         }
 180         parent = kobject_get(kobj->parent);
 181
 182         pr_debug("kobject %s: registering. parent: %s, set: %s\n",
 183                  kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>",
 184                  kobj->kset ? kobject_name(&kobj->kset->kobj) : "<NULL>" );
 185
 186         if (kobj->kset) {
 187                 spin_lock(&kobj->kset->list_lock);
 188
 189                 if (!parent)
 190                         parent = kobject_get(&kobj->kset->kobj);
 191
 192                 list_add_tail(&kobj->entry,&kobj->kset->list);
 193                 spin_unlock(&kobj->kset->list_lock);
 194                 kobj->parent = parent;
 195         }
 196
 197         error = create_dir(kobj);
 198         if (error) {
 199                 /* unlink does the kobject_put() for us */
 200                 unlink(kobj);
 201                 kobject_put(parent);
 202
 203                 /* be noisy on error issues */
 204                 if (error == -EEXIST)
 205                         printk(KERN_ERR "kobject_add failed for %s with "
 206                                "-EEXIST, don't try to register things with "
 207                                "the same name in the same directory.\n",
 208                                kobject_name(kobj));
 209                 else
 210                         printk(KERN_ERR "kobject_add failed for %s (%d)\n",
 211                                kobject_name(kobj), error);
 212                 dump_stack();
 213         }
 214
 215         return error;
 216 }
 217
 218 /**
 219  *      kobject_register - initialize and add an object.
 220  *      @kobj:  object in question.
 221  */
 222
 223 int kobject_register(struct kobject * kobj)
 224 {
 225         int error = -EINVAL;
 226         if (kobj) {
 227                 kobject_init(kobj);
 228                 error = kobject_add(kobj);
 229                 if (!error)
 230                         kobject_uevent(kobj, KOBJ_ADD);
 231         }
 232         return error;
 233 }
 234
 235 /**
 236  * kobject_set_name_vargs - Set the name of an kobject
 237  * @kobj: struct kobject to set the name of
 238  * @fmt: format string used to build the name
 239  * @vargs: vargs to format the string.
 240  */
 241 static int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
 242                                   va_list vargs)
 243 {
 244         va_list aq;
 245         char *name;
 246
 247         va_copy(aq, vargs);
 248         name = kvasprintf(GFP_KERNEL, fmt, vargs);
 249         va_end(aq);
 250
 251         if (!name)
 252                 return -ENOMEM;
 253
 254         /* Free the old name, if necessary. */
 255         kfree(kobj->k_name);
 256
 257         /* Now, set the new name */
 258         kobj->k_name = name;
 259
 260         return 0;
 261 }
 262
 263 /**
 264  * kobject_set_name - Set the name of a kobject
 265  * @kobj: struct kobject to set the name of
 266  * @fmt: format string used to build the name
 267  *
 268  * This sets the name of the kobject.  If you have already added the
 269  * kobject to the system, you must call kobject_rename() in order to
 270  * change the name of the kobject.
 271  */
 272 int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
 273 {
 274         va_list args;
 275         int retval;
 276
 277         va_start(args, fmt);
 278         retval = kobject_set_name_vargs(kobj, fmt, args);
 279         va_end(args);
 280
 281         return retval;
 282 }
 283 EXPORT_SYMBOL(kobject_set_name);
 284
 285 /**
 286  *      kobject_rename - change the name of an object
 287  *      @kobj:  object in question.
 288  *      @new_name: object's new name
 289  */
 290
 291 int kobject_rename(struct kobject * kobj, const char *new_name)
 292 {
 293         int error = 0;
 294         const char *devpath = NULL;
 295         char *devpath_string = NULL;
 296         char *envp[2];
 297
 298         kobj = kobject_get(kobj);
 299         if (!kobj)
 300                 return -EINVAL;
 301         if (!kobj->parent)
 302                 return -EINVAL;
 303
 304         /* see if this name is already in use */
 305         if (kobj->kset) {
 306                 struct kobject *temp_kobj;
 307                 temp_kobj = kset_find_obj(kobj->kset, new_name);
 308                 if (temp_kobj) {
 309                         printk(KERN_WARNING "kobject '%s' cannot be renamed "
 310                                "to '%s' as '%s' is already in existence.\n",
 311                                kobject_name(kobj), new_name, new_name);
 312                         kobject_put(temp_kobj);
 313                         return -EINVAL;
 314                 }
 315         }
 316
 317         devpath = kobject_get_path(kobj, GFP_KERNEL);
 318         if (!devpath) {
 319                 error = -ENOMEM;
 320                 goto out;
 321         }
 322         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 323         if (!devpath_string) {
 324                 error = -ENOMEM;
 325                 goto out;
 326         }
 327         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 328         envp[0] = devpath_string;
 329         envp[1] = NULL;
 330
 331         error = sysfs_rename_dir(kobj, new_name);
 332
 333         /* This function is mostly/only used for network interface.
 334          * Some hotplug package track interfaces by their name and
 335          * therefore want to know when the name is changed by the user. */
 336         if (!error)
 337                 kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 338
 339 out:
 340         kfree(devpath_string);
 341         kfree(devpath);
 342         kobject_put(kobj);
 343
 344         return error;
 345 }
 346
 347 /**
 348  *      kobject_move - move object to another parent
 349  *      @kobj:  object in question.
 350  *      @new_parent: object's new parent (can be NULL)
 351  */
 352
 353 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 354 {
 355         int error;
 356         struct kobject *old_parent;
 357         const char *devpath = NULL;
 358         char *devpath_string = NULL;
 359         char *envp[2];
 360
 361         kobj = kobject_get(kobj);
 362         if (!kobj)
 363                 return -EINVAL;
 364         new_parent = kobject_get(new_parent);
 365         if (!new_parent) {
 366                 if (kobj->kset)
 367                         new_parent = kobject_get(&kobj->kset->kobj);
 368         }
 369         /* old object path */
 370         devpath = kobject_get_path(kobj, GFP_KERNEL);
 371         if (!devpath) {
 372                 error = -ENOMEM;
 373                 goto out;
 374         }
 375         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 376         if (!devpath_string) {
 377                 error = -ENOMEM;
 378                 goto out;
 379         }
 380         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 381         envp[0] = devpath_string;
 382         envp[1] = NULL;
 383         error = sysfs_move_dir(kobj, new_parent);
 384         if (error)
 385                 goto out;
 386         old_parent = kobj->parent;
 387         kobj->parent = new_parent;
 388         new_parent = NULL;
 389         kobject_put(old_parent);
 390         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 391 out:
 392         kobject_put(new_parent);
 393         kobject_put(kobj);
 394         kfree(devpath_string);
 395         kfree(devpath);
 396         return error;
 397 }
 398
 399 /**
 400  *      kobject_del - unlink kobject from hierarchy.
 401  *      @kobj:  object.
 402  */
 403
 404 void kobject_del(struct kobject * kobj)
 405 {
 406         if (!kobj)
 407                 return;
 408         sysfs_remove_dir(kobj);
 409         unlink(kobj);
 410 }
 411
 412 /**
 413  *      kobject_unregister - remove object from hierarchy and decrement refcount.
 414  *      @kobj:  object going away.
 415  */
 416
 417 void kobject_unregister(struct kobject * kobj)
 418 {
 419         if (!kobj)
 420                 return;
 421         pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
 422         kobject_uevent(kobj, KOBJ_REMOVE);
 423         kobject_del(kobj);
 424         kobject_put(kobj);
 425 }
 426
 427 /**
 428  *      kobject_get - increment refcount for object.
 429  *      @kobj:  object.
 430  */
 431
 432 struct kobject * kobject_get(struct kobject * kobj)
 433 {
 434         if (kobj)
 435                 kref_get(&kobj->kref);
 436         return kobj;
 437 }
 438
 439 /**
 440  *      kobject_cleanup - free kobject resources.
 441  *      @kobj:  object.
 442  */
 443
 444 void kobject_cleanup(struct kobject * kobj)
 445 {
 446         struct kobj_type * t = get_ktype(kobj);
 447         struct kset * s = kobj->kset;
 448         struct kobject * parent = kobj->parent;
 449         const char *name = kobj->k_name;
 450
 451         pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
 452         if (t && t->release) {
 453                 t->release(kobj);
 454                 /* If we have a release function, we can guess that this was
 455                  * not a statically allocated kobject, so we should be safe to
 456                  * free the name */
 457                 kfree(name);
 458         }
 459         if (s)
 460                 kset_put(s);
 461         kobject_put(parent);
 462 }
 463
 464 static void kobject_release(struct kref *kref)
 465 {
 466         kobject_cleanup(container_of(kref, struct kobject, kref));
 467 }
 468
 469 /**
 470  *      kobject_put - decrement refcount for object.
 471  *      @kobj:  object.
 472  *
 473  *      Decrement the refcount, and if 0, call kobject_cleanup().
 474  */
 475 void kobject_put(struct kobject * kobj)
 476 {
 477         if (kobj)
 478                 kref_put(&kobj->kref, kobject_release);
 479 }
 480
 481
 482 static void dir_release(struct kobject *kobj)
 483 {
 484         kfree(kobj);
 485 }
 486
 487 static struct kobj_type dir_ktype = {
 488         .release        = dir_release,
 489         .sysfs_ops      = NULL,
 490         .default_attrs  = NULL,
 491 };
 492
 493 /**
 494  *      kobject_kset_add_dir - add sub directory of object.
 495  *      @kset:          kset the directory is belongs to.
 496  *      @parent:        object in which a directory is created.
 497  *      @name:  directory name.
 498  *
 499  *      Add a plain directory object as child of given object.
 500  */
 501 struct kobject *kobject_kset_add_dir(struct kset *kset,
 502                                      struct kobject *parent, const char *name)
 503 {
 504         struct kobject *k;
 505         int ret;
 506
 507         if (!parent)
 508                 return NULL;
 509
 510         k = kzalloc(sizeof(*k), GFP_KERNEL);
 511         if (!k)
 512                 return NULL;
 513
 514         k->kset = kset;
 515         k->parent = parent;
 516         k->ktype = &dir_ktype;
 517         kobject_set_name(k, name);
 518         ret = kobject_register(k);
 519         if (ret < 0) {
 520                 printk(KERN_WARNING "%s: kobject_register error: %d\n",
 521                         __func__, ret);
 522                 kobject_del(k);
 523                 return NULL;
 524         }
 525
 526         return k;
 527 }
 528
 529 /**
 530  *      kobject_add_dir - add sub directory of object.
 531  *      @parent:        object in which a directory is created.
 532  *      @name:  directory name.
 533  *
 534  *      Add a plain directory object as child of given object.
 535  */
 536 struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
 537 {
 538         return kobject_kset_add_dir(NULL, parent, name);
 539 }
 540
 541 /**
 542  *      kset_init - initialize a kset for use
 543  *      @k:     kset
 544  */
 545
 546 void kset_init(struct kset * k)
 547 {
 548         kobject_init(&k->kobj);
 549         INIT_LIST_HEAD(&k->list);
 550         spin_lock_init(&k->list_lock);
 551 }
 552
 553
 554 /**
 555  *      kset_add - add a kset object to the hierarchy.
 556  *      @k:     kset.
 557  */
 558
 559 int kset_add(struct kset * k)
 560 {
 561         return kobject_add(&k->kobj);
 562 }
 563
 564
 565 /**
 566  *      kset_register - initialize and add a kset.
 567  *      @k:     kset.
 568  */
 569
 570 int kset_register(struct kset * k)
 571 {
 572         int err;
 573
 574         if (!k)
 575                 return -EINVAL;
 576
 577         kset_init(k);
 578         err = kset_add(k);
 579         if (err)
 580                 return err;
 581         kobject_uevent(&k->kobj, KOBJ_ADD);
 582         return 0;
 583 }
 584
 585
 586 /**
 587  *      kset_unregister - remove a kset.
 588  *      @k:     kset.
 589  */
 590
 591 void kset_unregister(struct kset * k)
 592 {
 593         if (!k)
 594                 return;
 595         kobject_unregister(&k->kobj);
 596 }
 597
 598
 599 /**
 600  *      kset_find_obj - search for object in kset.
 601  *      @kset:  kset we're looking in.
 602  *      @name:  object's name.
 603  *
 604  *      Lock kset via @kset->subsys, and iterate over @kset->list,
 605  *      looking for a matching kobject. If matching object is found
 606  *      take a reference and return the object.
 607  */
 608
 609 struct kobject * kset_find_obj(struct kset * kset, const char * name)
 610 {
 611         struct list_head * entry;
 612         struct kobject * ret = NULL;
 613
 614         spin_lock(&kset->list_lock);
 615         list_for_each(entry,&kset->list) {
 616                 struct kobject * k = to_kobj(entry);
 617                 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
 618                         ret = kobject_get(k);
 619                         break;
 620                 }
 621         }
 622         spin_unlock(&kset->list_lock);
 623         return ret;
 624 }
 625
 626 int subsystem_register(struct kset *s)
 627 {
 628         return kset_register(s);
 629 }
 630
 631 void subsystem_unregister(struct kset *s)
 632 {
 633         kset_unregister(s);
 634 }
 635
 636 /**
 637  *      subsystem_create_file - export sysfs attribute file.
 638  *      @s:     subsystem.
 639  *      @a:     subsystem attribute descriptor.
 640  */
 641
 642 int subsys_create_file(struct kset *s, struct subsys_attribute *a)
 643 {
 644         int error = 0;
 645
 646         if (!s || !a)
 647                 return -EINVAL;
 648
 649         if (kset_get(s)) {
 650                 error = sysfs_create_file(&s->kobj, &a->attr);
 651                 kset_put(s);
 652         }
 653         return error;
 654 }
 655
 656 EXPORT_SYMBOL(kobject_init);
 657 EXPORT_SYMBOL(kobject_register);
 658 EXPORT_SYMBOL(kobject_unregister);
 659 EXPORT_SYMBOL(kobject_get);
 660 EXPORT_SYMBOL(kobject_put);
 661 EXPORT_SYMBOL(kobject_add);
 662 EXPORT_SYMBOL(kobject_del);
 663
 664 EXPORT_SYMBOL(kset_register);
 665 EXPORT_SYMBOL(kset_unregister);
 666
 667 EXPORT_SYMBOL(subsystem_register);
 668 EXPORT_SYMBOL(subsystem_unregister);
 669 EXPORT_SYMBOL(subsys_create_file);