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  *
   6  * This file is released under the GPLv2.
   7  *
   8  *
   9  * Please see the file Documentation/kobject.txt for critical information
  10  * about using the kobject interface.
  11  */
  12
  13 #include <linux/kobject.h>
  14 #include <linux/string.h>
  15 #include <linux/module.h>
  16 #include <linux/stat.h>
  17 #include <linux/slab.h>
  18
  19 /**
  20  *      populate_dir - populate directory with attributes.
  21  *      @kobj:  object we're working on.
  22  *
  23  *      Most subsystems have a set of default attributes that
  24  *      are associated with an object that registers with them.
  25  *      This is a helper called during object registration that
  26  *      loops through the default attributes of the subsystem
  27  *      and creates attributes files for them in sysfs.
  28  *
  29  */
  30
  31 static int populate_dir(struct kobject * kobj)
  32 {
  33         struct kobj_type * t = get_ktype(kobj);
  34         struct attribute * attr;
  35         int error = 0;
  36         int i;
  37
  38         if (t && t->default_attrs) {
  39                 for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
  40                         if ((error = sysfs_create_file(kobj,attr)))
  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                         if ((error = populate_dir(kobj)))
  54                                 sysfs_remove_dir(kobj);
  55                 }
  56         }
  57         return error;
  58 }
  59
  60 static inline struct kobject * to_kobj(struct list_head * entry)
  61 {
  62         return container_of(entry,struct kobject,entry);
  63 }
  64
  65 static int get_kobj_path_length(struct kobject *kobj)
  66 {
  67         int length = 1;
  68         struct kobject * parent = kobj;
  69
  70         /* walk up the ancestors until we hit the one pointing to the
  71          * root.
  72          * Add 1 to strlen for leading '/' of each level.
  73          */
  74         do {
  75                 if (kobject_name(parent) == NULL)
  76                         return 0;
  77                 length += strlen(kobject_name(parent)) + 1;
  78                 parent = parent->parent;
  79         } while (parent);
  80         return length;
  81 }
  82
  83 static void fill_kobj_path(struct kobject *kobj, char *path, int length)
  84 {
  85         struct kobject * parent;
  86
  87         --length;
  88         for (parent = kobj; parent; parent = parent->parent) {
  89                 int cur = strlen(kobject_name(parent));
  90                 /* back up enough to print this name with '/' */
  91                 length -= cur;
  92                 strncpy (path + length, kobject_name(parent), cur);
  93                 *(path + --length) = '/';
  94         }
  95
  96         pr_debug("%s: path = '%s'\n",__FUNCTION__,path);
  97 }
  98
  99 /**
 100  * kobject_get_path - generate and return the path associated with a given kobj
 101  * and kset pair.  The result must be freed by the caller with kfree().
 102  *
 103  * @kobj:       kobject in question, with which to build the path
 104  * @gfp_mask:   the allocation type used to allocate the path
 105  */
 106 char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
 107 {
 108         char *path;
 109         int len;
 110
 111         len = get_kobj_path_length(kobj);
 112         if (len == 0)
 113                 return NULL;
 114         path = kzalloc(len, gfp_mask);
 115         if (!path)
 116                 return NULL;
 117         fill_kobj_path(kobj, path, len);
 118
 119         return path;
 120 }
 121 EXPORT_SYMBOL_GPL(kobject_get_path);
 122
 123 /**
 124  *      kobject_init - initialize object.
 125  *      @kobj:  object in question.
 126  */
 127 void kobject_init(struct kobject * kobj)
 128 {
 129         kref_init(&kobj->kref);
 130         INIT_LIST_HEAD(&kobj->entry);
 131         init_waitqueue_head(&kobj->poll);
 132         kobj->kset = kset_get(kobj->kset);
 133 }
 134
 135
 136 /**
 137  *      unlink - remove kobject from kset list.
 138  *      @kobj:  kobject.
 139  *
 140  *      Remove the kobject from the kset list and decrement
 141  *      its parent's refcount.
 142  *      This is separated out, so we can use it in both
 143  *      kobject_del() and kobject_add() on error.
 144  */
 145
 146 static void unlink(struct kobject * kobj)
 147 {
 148         if (kobj->kset) {
 149                 spin_lock(&kobj->kset->list_lock);
 150                 list_del_init(&kobj->entry);
 151                 spin_unlock(&kobj->kset->list_lock);
 152         }
 153         kobject_put(kobj);
 154 }
 155
 156 /**
 157  *      kobject_add - add an object to the hierarchy.
 158  *      @kobj:  object.
 159  */
 160
 161 int kobject_add(struct kobject * kobj)
 162 {
 163         int error = 0;
 164         struct kobject * parent;
 165
 166         if (!(kobj = kobject_get(kobj)))
 167                 return -ENOENT;
 168         if (!kobj->k_name)
 169                 kobj->k_name = kobj->name;
 170         if (!kobj->k_name) {
 171                 pr_debug("kobject attempted to be registered with no name!\n");
 172                 WARN_ON(1);
 173                 return -EINVAL;
 174         }
 175         parent = kobject_get(kobj->parent);
 176
 177         pr_debug("kobject %s: registering. parent: %s, set: %s\n",
 178                  kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>",
 179                  kobj->kset ? kobj->kset->kobj.name : "<NULL>" );
 180
 181         if (kobj->kset) {
 182                 spin_lock(&kobj->kset->list_lock);
 183
 184                 if (!parent)
 185                         parent = kobject_get(&kobj->kset->kobj);
 186
 187                 list_add_tail(&kobj->entry,&kobj->kset->list);
 188                 spin_unlock(&kobj->kset->list_lock);
 189         }
 190         kobj->parent = parent;
 191
 192         error = create_dir(kobj);
 193         if (error) {
 194                 /* unlink does the kobject_put() for us */
 195                 unlink(kobj);
 196                 if (parent)
 197                         kobject_put(parent);
 198
 199                 /* be noisy on error issues */
 200                 if (error == -EEXIST)
 201                         printk("kobject_add failed for %s with -EEXIST, "
 202                                "don't try to register things with the "
 203                                "same name in the same directory.\n",
 204                                kobject_name(kobj));
 205                 else
 206                         printk("kobject_add failed for %s (%d)\n",
 207                                kobject_name(kobj), error);
 208                  dump_stack();
 209         }
 210
 211         return error;
 212 }
 213
 214
 215 /**
 216  *      kobject_register - initialize and add an object.
 217  *      @kobj:  object in question.
 218  */
 219
 220 int kobject_register(struct kobject * kobj)
 221 {
 222         int error = -EINVAL;
 223         if (kobj) {
 224                 kobject_init(kobj);
 225                 error = kobject_add(kobj);
 226                 if (!error)
 227                         kobject_uevent(kobj, KOBJ_ADD);
 228         }
 229         return error;
 230 }
 231
 232
 233 /**
 234  *      kobject_set_name - Set the name of an object
 235  *      @kobj:  object.
 236  *      @fmt:   format string used to build the name
 237  *
 238  *      If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
 239  *      string that @kobj->k_name points to. Otherwise, use the static
 240  *      @kobj->name array.
 241  */
 242 int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
 243 {
 244         int error = 0;
 245         int limit = KOBJ_NAME_LEN;
 246         int need;
 247         va_list args;
 248         char * name;
 249
 250         /*
 251          * First, try the static array
 252          */
 253         va_start(args,fmt);
 254         need = vsnprintf(kobj->name,limit,fmt,args);
 255         va_end(args);
 256         if (need < limit)
 257                 name = kobj->name;
 258         else {
 259                 /*
 260                  * Need more space? Allocate it and try again
 261                  */
 262                 limit = need + 1;
 263                 name = kmalloc(limit,GFP_KERNEL);
 264                 if (!name) {
 265                         error = -ENOMEM;
 266                         goto Done;
 267                 }
 268                 va_start(args,fmt);
 269                 need = vsnprintf(name,limit,fmt,args);
 270                 va_end(args);
 271
 272                 /* Still? Give up. */
 273                 if (need >= limit) {
 274                         kfree(name);
 275                         error = -EFAULT;
 276                         goto Done;
 277                 }
 278         }
 279
 280         /* Free the old name, if necessary. */
 281         if (kobj->k_name && kobj->k_name != kobj->name)
 282                 kfree(kobj->k_name);
 283
 284         /* Now, set the new name */
 285         kobj->k_name = name;
 286  Done:
 287         return error;
 288 }
 289
 290 EXPORT_SYMBOL(kobject_set_name);
 291
 292
 293 /**
 294  *      kobject_rename - change the name of an object
 295  *      @kobj:  object in question.
 296  *      @new_name: object's new name
 297  */
 298
 299 int kobject_rename(struct kobject * kobj, const char *new_name)
 300 {
 301         int error = 0;
 302
 303         kobj = kobject_get(kobj);
 304         if (!kobj)
 305                 return -EINVAL;
 306         error = sysfs_rename_dir(kobj, new_name);
 307         kobject_put(kobj);
 308
 309         return error;
 310 }
 311
 312 /**
 313  *      kobject_move - move object to another parent
 314  *      @kobj:  object in question.
 315  *      @new_parent: object's new parent
 316  */
 317
 318 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 319 {
 320         int error;
 321         struct kobject *old_parent;
 322         const char *devpath = NULL;
 323         char *devpath_string = NULL;
 324         char *envp[2];
 325
 326         kobj = kobject_get(kobj);
 327         if (!kobj)
 328                 return -EINVAL;
 329         new_parent = kobject_get(new_parent);
 330         if (!new_parent) {
 331                 error = -EINVAL;
 332                 goto out;
 333         }
 334         /* old object path */
 335         devpath = kobject_get_path(kobj, GFP_KERNEL);
 336         if (!devpath) {
 337                 error = -ENOMEM;
 338                 goto out;
 339         }
 340         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 341         if (!devpath_string) {
 342                 error = -ENOMEM;
 343                 goto out;
 344         }
 345         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 346         envp[0] = devpath_string;
 347         envp[1] = NULL;
 348         error = sysfs_move_dir(kobj, new_parent);
 349         if (error)
 350                 goto out;
 351         old_parent = kobj->parent;
 352         kobj->parent = new_parent;
 353         kobject_put(old_parent);
 354         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 355 out:
 356         kobject_put(kobj);
 357         kfree(devpath_string);
 358         kfree(devpath);
 359         return error;
 360 }
 361
 362 /**
 363  *      kobject_del - unlink kobject from hierarchy.
 364  *      @kobj:  object.
 365  */
 366
 367 void kobject_del(struct kobject * kobj)
 368 {
 369         sysfs_remove_dir(kobj);
 370         unlink(kobj);
 371 }
 372
 373 /**
 374  *      kobject_unregister - remove object from hierarchy and decrement refcount.
 375  *      @kobj:  object going away.
 376  */
 377
 378 void kobject_unregister(struct kobject * kobj)
 379 {
 380         pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
 381         kobject_uevent(kobj, KOBJ_REMOVE);
 382         kobject_del(kobj);
 383         kobject_put(kobj);
 384 }
 385
 386 /**
 387  *      kobject_get - increment refcount for object.
 388  *      @kobj:  object.
 389  */
 390
 391 struct kobject * kobject_get(struct kobject * kobj)
 392 {
 393         if (kobj)
 394                 kref_get(&kobj->kref);
 395         return kobj;
 396 }
 397
 398 /**
 399  *      kobject_cleanup - free kobject resources.
 400  *      @kobj:  object.
 401  */
 402
 403 void kobject_cleanup(struct kobject * kobj)
 404 {
 405         struct kobj_type * t = get_ktype(kobj);
 406         struct kset * s = kobj->kset;
 407         struct kobject * parent = kobj->parent;
 408
 409         pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
 410         if (kobj->k_name != kobj->name)
 411                 kfree(kobj->k_name);
 412         kobj->k_name = NULL;
 413         if (t && t->release)
 414                 t->release(kobj);
 415         if (s)
 416                 kset_put(s);
 417         if (parent)
 418                 kobject_put(parent);
 419 }
 420
 421 static void kobject_release(struct kref *kref)
 422 {
 423         kobject_cleanup(container_of(kref, struct kobject, kref));
 424 }
 425
 426 /**
 427  *      kobject_put - decrement refcount for object.
 428  *      @kobj:  object.
 429  *
 430  *      Decrement the refcount, and if 0, call kobject_cleanup().
 431  */
 432 void kobject_put(struct kobject * kobj)
 433 {
 434         if (kobj)
 435                 kref_put(&kobj->kref, kobject_release);
 436 }
 437
 438
 439 static void dir_release(struct kobject *kobj)
 440 {
 441         kfree(kobj);
 442 }
 443
 444 static struct kobj_type dir_ktype = {
 445         .release        = dir_release,
 446         .sysfs_ops      = NULL,
 447         .default_attrs  = NULL,
 448 };
 449
 450 /**
 451  *      kobject_add_dir - add sub directory of object.
 452  *      @parent:        object in which a directory is created.
 453  *      @name:  directory name.
 454  *
 455  *      Add a plain directory object as child of given object.
 456  */
 457 struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
 458 {
 459         struct kobject *k;
 460         int ret;
 461
 462         if (!parent)
 463                 return NULL;
 464
 465         k = kzalloc(sizeof(*k), GFP_KERNEL);
 466         if (!k)
 467                 return NULL;
 468
 469         k->parent = parent;
 470         k->ktype = &dir_ktype;
 471         kobject_set_name(k, name);
 472         ret = kobject_register(k);
 473         if (ret < 0) {
 474                 printk(KERN_WARNING "kobject_add_dir: "
 475                         "kobject_register error: %d\n", ret);
 476                 kobject_del(k);
 477                 return NULL;
 478         }
 479
 480         return k;
 481 }
 482
 483 /**
 484  *      kset_init - initialize a kset for use
 485  *      @k:     kset
 486  */
 487
 488 void kset_init(struct kset * k)
 489 {
 490         kobject_init(&k->kobj);
 491         INIT_LIST_HEAD(&k->list);
 492         spin_lock_init(&k->list_lock);
 493 }
 494
 495
 496 /**
 497  *      kset_add - add a kset object to the hierarchy.
 498  *      @k:     kset.
 499  *
 500  *      Simply, this adds the kset's embedded kobject to the
 501  *      hierarchy.
 502  *      We also try to make sure that the kset's embedded kobject
 503  *      has a parent before it is added. We only care if the embedded
 504  *      kobject is not part of a kset itself, since kobject_add()
 505  *      assigns a parent in that case.
 506  *      If that is the case, and the kset has a controlling subsystem,
 507  *      then we set the kset's parent to be said subsystem.
 508  */
 509
 510 int kset_add(struct kset * k)
 511 {
 512         if (!k->kobj.parent && !k->kobj.kset && k->subsys)
 513                 k->kobj.parent = &k->subsys->kset.kobj;
 514
 515         return kobject_add(&k->kobj);
 516 }
 517
 518
 519 /**
 520  *      kset_register - initialize and add a kset.
 521  *      @k:     kset.
 522  */
 523
 524 int kset_register(struct kset * k)
 525 {
 526         kset_init(k);
 527         return kset_add(k);
 528 }
 529
 530
 531 /**
 532  *      kset_unregister - remove a kset.
 533  *      @k:     kset.
 534  */
 535
 536 void kset_unregister(struct kset * k)
 537 {
 538         kobject_unregister(&k->kobj);
 539 }
 540
 541
 542 /**
 543  *      kset_find_obj - search for object in kset.
 544  *      @kset:  kset we're looking in.
 545  *      @name:  object's name.
 546  *
 547  *      Lock kset via @kset->subsys, and iterate over @kset->list,
 548  *      looking for a matching kobject. If matching object is found
 549  *      take a reference and return the object.
 550  */
 551
 552 struct kobject * kset_find_obj(struct kset * kset, const char * name)
 553 {
 554         struct list_head * entry;
 555         struct kobject * ret = NULL;
 556
 557         spin_lock(&kset->list_lock);
 558         list_for_each(entry,&kset->list) {
 559                 struct kobject * k = to_kobj(entry);
 560                 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
 561                         ret = kobject_get(k);
 562                         break;
 563                 }
 564         }
 565         spin_unlock(&kset->list_lock);
 566         return ret;
 567 }
 568
 569
 570 void subsystem_init(struct subsystem * s)
 571 {
 572         init_rwsem(&s->rwsem);
 573         kset_init(&s->kset);
 574 }
 575
 576 /**
 577  *      subsystem_register - register a subsystem.
 578  *      @s:     the subsystem we're registering.
 579  *
 580  *      Once we register the subsystem, we want to make sure that
 581  *      the kset points back to this subsystem for correct usage of
 582  *      the rwsem.
 583  */
 584
 585 int subsystem_register(struct subsystem * s)
 586 {
 587         int error;
 588
 589         subsystem_init(s);
 590         pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
 591
 592         if (!(error = kset_add(&s->kset))) {
 593                 if (!s->kset.subsys)
 594                         s->kset.subsys = s;
 595         }
 596         return error;
 597 }
 598
 599 void subsystem_unregister(struct subsystem * s)
 600 {
 601         pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
 602         kset_unregister(&s->kset);
 603 }
 604
 605
 606 /**
 607  *      subsystem_create_file - export sysfs attribute file.
 608  *      @s:     subsystem.
 609  *      @a:     subsystem attribute descriptor.
 610  */
 611
 612 int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
 613 {
 614         int error = 0;
 615         if (subsys_get(s)) {
 616                 error = sysfs_create_file(&s->kset.kobj,&a->attr);
 617                 subsys_put(s);
 618         }
 619         return error;
 620 }
 621
 622
 623 /**
 624  *      subsystem_remove_file - remove sysfs attribute file.
 625  *      @s:     subsystem.
 626  *      @a:     attribute desciptor.
 627  */
 628 #if 0
 629 void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
 630 {
 631         if (subsys_get(s)) {
 632                 sysfs_remove_file(&s->kset.kobj,&a->attr);
 633                 subsys_put(s);
 634         }
 635 }
 636 #endif  /*  0  */
 637
 638 EXPORT_SYMBOL(kobject_init);
 639 EXPORT_SYMBOL(kobject_register);
 640 EXPORT_SYMBOL(kobject_unregister);
 641 EXPORT_SYMBOL(kobject_get);
 642 EXPORT_SYMBOL(kobject_put);
 643 EXPORT_SYMBOL(kobject_add);
 644 EXPORT_SYMBOL(kobject_del);
 645
 646 EXPORT_SYMBOL(kset_register);
 647 EXPORT_SYMBOL(kset_unregister);
 648
 649 EXPORT_SYMBOL(subsystem_register);
 650 EXPORT_SYMBOL(subsystem_unregister);
 651 EXPORT_SYMBOL(subsys_create_file);