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 = kmalloc(len, gfp_mask);
 115         if (!path)
 116                 return NULL;
 117         memset(path, 0x00, len);
 118         fill_kobj_path(kobj, path, len);
 119
 120         return path;
 121 }
 122 EXPORT_SYMBOL_GPL(kobject_get_path);
 123
 124 /**
 125  *      kobject_init - initialize object.
 126  *      @kobj:  object in question.
 127  */
 128 void kobject_init(struct kobject * kobj)
 129 {
 130         kref_init(&kobj->kref);
 131         INIT_LIST_HEAD(&kobj->entry);
 132         init_waitqueue_head(&kobj->poll);
 133         kobj->kset = kset_get(kobj->kset);
 134 }
 135
 136
 137 /**
 138  *      unlink - remove kobject from kset list.
 139  *      @kobj:  kobject.
 140  *
 141  *      Remove the kobject from the kset list and decrement
 142  *      its parent's refcount.
 143  *      This is separated out, so we can use it in both
 144  *      kobject_del() and kobject_add() on error.
 145  */
 146
 147 static void unlink(struct kobject * kobj)
 148 {
 149         if (kobj->kset) {
 150                 spin_lock(&kobj->kset->list_lock);
 151                 list_del_init(&kobj->entry);
 152                 spin_unlock(&kobj->kset->list_lock);
 153         }
 154         kobject_put(kobj);
 155 }
 156
 157 /**
 158  *      kobject_add - add an object to the hierarchy.
 159  *      @kobj:  object.
 160  */
 161
 162 int kobject_add(struct kobject * kobj)
 163 {
 164         int error = 0;
 165         struct kobject * parent;
 166
 167         if (!(kobj = kobject_get(kobj)))
 168                 return -ENOENT;
 169         if (!kobj->k_name)
 170                 kobj->k_name = kobj->name;
 171         if (!kobj->k_name) {
 172                 pr_debug("kobject attempted to be registered with no name!\n");
 173                 WARN_ON(1);
 174                 return -EINVAL;
 175         }
 176         parent = kobject_get(kobj->parent);
 177
 178         pr_debug("kobject %s: registering. parent: %s, set: %s\n",
 179                  kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>",
 180                  kobj->kset ? kobj->kset->kobj.name : "<NULL>" );
 181
 182         if (kobj->kset) {
 183                 spin_lock(&kobj->kset->list_lock);
 184
 185                 if (!parent)
 186                         parent = kobject_get(&kobj->kset->kobj);
 187
 188                 list_add_tail(&kobj->entry,&kobj->kset->list);
 189                 spin_unlock(&kobj->kset->list_lock);
 190         }
 191         kobj->parent = parent;
 192
 193         error = create_dir(kobj);
 194         if (error) {
 195                 /* unlink does the kobject_put() for us */
 196                 unlink(kobj);
 197                 if (parent)
 198                         kobject_put(parent);
 199
 200                 /* be noisy on error issues */
 201                 if (error == -EEXIST)
 202                         printk("kobject_add failed for %s with -EEXIST, "
 203                                "don't try to register things with the "
 204                                "same name in the same directory.\n",
 205                                kobject_name(kobj));
 206                 else
 207                         printk("kobject_add failed for %s (%d)\n",
 208                                kobject_name(kobj), error);
 209                  dump_stack();
 210         }
 211
 212         return error;
 213 }
 214
 215
 216 /**
 217  *      kobject_register - initialize and add an object.
 218  *      @kobj:  object in question.
 219  */
 220
 221 int kobject_register(struct kobject * kobj)
 222 {
 223         int error = -EINVAL;
 224         if (kobj) {
 225                 kobject_init(kobj);
 226                 error = kobject_add(kobj);
 227                 if (!error)
 228                         kobject_uevent(kobj, KOBJ_ADD);
 229         }
 230         return error;
 231 }
 232
 233
 234 /**
 235  *      kobject_set_name - Set the name of an object
 236  *      @kobj:  object.
 237  *      @fmt:   format string used to build the name
 238  *
 239  *      If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
 240  *      string that @kobj->k_name points to. Otherwise, use the static
 241  *      @kobj->name array.
 242  */
 243 int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
 244 {
 245         int error = 0;
 246         int limit = KOBJ_NAME_LEN;
 247         int need;
 248         va_list args;
 249         char * name;
 250
 251         /*
 252          * First, try the static array
 253          */
 254         va_start(args,fmt);
 255         need = vsnprintf(kobj->name,limit,fmt,args);
 256         va_end(args);
 257         if (need < limit)
 258                 name = kobj->name;
 259         else {
 260                 /*
 261                  * Need more space? Allocate it and try again
 262                  */
 263                 limit = need + 1;
 264                 name = kmalloc(limit,GFP_KERNEL);
 265                 if (!name) {
 266                         error = -ENOMEM;
 267                         goto Done;
 268                 }
 269                 va_start(args,fmt);
 270                 need = vsnprintf(name,limit,fmt,args);
 271                 va_end(args);
 272
 273                 /* Still? Give up. */
 274                 if (need >= limit) {
 275                         kfree(name);
 276                         error = -EFAULT;
 277                         goto Done;
 278                 }
 279         }
 280
 281         /* Free the old name, if necessary. */
 282         if (kobj->k_name && kobj->k_name != kobj->name)
 283                 kfree(kobj->k_name);
 284
 285         /* Now, set the new name */
 286         kobj->k_name = name;
 287  Done:
 288         return error;
 289 }
 290
 291 EXPORT_SYMBOL(kobject_set_name);
 292
 293
 294 /**
 295  *      kobject_rename - change the name of an object
 296  *      @kobj:  object in question.
 297  *      @new_name: object's new name
 298  */
 299
 300 int kobject_rename(struct kobject * kobj, const char *new_name)
 301 {
 302         int error = 0;
 303
 304         kobj = kobject_get(kobj);
 305         if (!kobj)
 306                 return -EINVAL;
 307         error = sysfs_rename_dir(kobj, new_name);
 308         kobject_put(kobj);
 309
 310         return error;
 311 }
 312
 313 /**
 314  *      kobject_del - unlink kobject from hierarchy.
 315  *      @kobj:  object.
 316  */
 317
 318 void kobject_del(struct kobject * kobj)
 319 {
 320         sysfs_remove_dir(kobj);
 321         unlink(kobj);
 322 }
 323
 324 /**
 325  *      kobject_unregister - remove object from hierarchy and decrement refcount.
 326  *      @kobj:  object going away.
 327  */
 328
 329 void kobject_unregister(struct kobject * kobj)
 330 {
 331         pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
 332         kobject_uevent(kobj, KOBJ_REMOVE);
 333         kobject_del(kobj);
 334         kobject_put(kobj);
 335 }
 336
 337 /**
 338  *      kobject_get - increment refcount for object.
 339  *      @kobj:  object.
 340  */
 341
 342 struct kobject * kobject_get(struct kobject * kobj)
 343 {
 344         if (kobj)
 345                 kref_get(&kobj->kref);
 346         return kobj;
 347 }
 348
 349 /**
 350  *      kobject_cleanup - free kobject resources.
 351  *      @kobj:  object.
 352  */
 353
 354 void kobject_cleanup(struct kobject * kobj)
 355 {
 356         struct kobj_type * t = get_ktype(kobj);
 357         struct kset * s = kobj->kset;
 358         struct kobject * parent = kobj->parent;
 359
 360         pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
 361         if (kobj->k_name != kobj->name)
 362                 kfree(kobj->k_name);
 363         kobj->k_name = NULL;
 364         if (t && t->release)
 365                 t->release(kobj);
 366         if (s)
 367                 kset_put(s);
 368         if (parent)
 369                 kobject_put(parent);
 370 }
 371
 372 static void kobject_release(struct kref *kref)
 373 {
 374         kobject_cleanup(container_of(kref, struct kobject, kref));
 375 }
 376
 377 /**
 378  *      kobject_put - decrement refcount for object.
 379  *      @kobj:  object.
 380  *
 381  *      Decrement the refcount, and if 0, call kobject_cleanup().
 382  */
 383 void kobject_put(struct kobject * kobj)
 384 {
 385         if (kobj)
 386                 kref_put(&kobj->kref, kobject_release);
 387 }
 388
 389
 390 static void dir_release(struct kobject *kobj)
 391 {
 392         kfree(kobj);
 393 }
 394
 395 static struct kobj_type dir_ktype = {
 396         .release        = dir_release,
 397         .sysfs_ops      = NULL,
 398         .default_attrs  = NULL,
 399 };
 400
 401 /**
 402  *      kobject_add_dir - add sub directory of object.
 403  *      @parent:        object in which a directory is created.
 404  *      @name:  directory name.
 405  *
 406  *      Add a plain directory object as child of given object.
 407  */
 408 struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
 409 {
 410         struct kobject *k;
 411         int ret;
 412
 413         if (!parent)
 414                 return NULL;
 415
 416         k = kzalloc(sizeof(*k), GFP_KERNEL);
 417         if (!k)
 418                 return NULL;
 419
 420         k->parent = parent;
 421         k->ktype = &dir_ktype;
 422         kobject_set_name(k, name);
 423         ret = kobject_register(k);
 424         if (ret < 0) {
 425                 printk(KERN_WARNING "kobject_add_dir: "
 426                         "kobject_register error: %d\n", ret);
 427                 kobject_del(k);
 428                 return NULL;
 429         }
 430
 431         return k;
 432 }
 433
 434 /**
 435  *      kset_init - initialize a kset for use
 436  *      @k:     kset
 437  */
 438
 439 void kset_init(struct kset * k)
 440 {
 441         kobject_init(&k->kobj);
 442         INIT_LIST_HEAD(&k->list);
 443         spin_lock_init(&k->list_lock);
 444 }
 445
 446
 447 /**
 448  *      kset_add - add a kset object to the hierarchy.
 449  *      @k:     kset.
 450  *
 451  *      Simply, this adds the kset's embedded kobject to the
 452  *      hierarchy.
 453  *      We also try to make sure that the kset's embedded kobject
 454  *      has a parent before it is added. We only care if the embedded
 455  *      kobject is not part of a kset itself, since kobject_add()
 456  *      assigns a parent in that case.
 457  *      If that is the case, and the kset has a controlling subsystem,
 458  *      then we set the kset's parent to be said subsystem.
 459  */
 460
 461 int kset_add(struct kset * k)
 462 {
 463         if (!k->kobj.parent && !k->kobj.kset && k->subsys)
 464                 k->kobj.parent = &k->subsys->kset.kobj;
 465
 466         return kobject_add(&k->kobj);
 467 }
 468
 469
 470 /**
 471  *      kset_register - initialize and add a kset.
 472  *      @k:     kset.
 473  */
 474
 475 int kset_register(struct kset * k)
 476 {
 477         kset_init(k);
 478         return kset_add(k);
 479 }
 480
 481
 482 /**
 483  *      kset_unregister - remove a kset.
 484  *      @k:     kset.
 485  */
 486
 487 void kset_unregister(struct kset * k)
 488 {
 489         kobject_unregister(&k->kobj);
 490 }
 491
 492
 493 /**
 494  *      kset_find_obj - search for object in kset.
 495  *      @kset:  kset we're looking in.
 496  *      @name:  object's name.
 497  *
 498  *      Lock kset via @kset->subsys, and iterate over @kset->list,
 499  *      looking for a matching kobject. If matching object is found
 500  *      take a reference and return the object.
 501  */
 502
 503 struct kobject * kset_find_obj(struct kset * kset, const char * name)
 504 {
 505         struct list_head * entry;
 506         struct kobject * ret = NULL;
 507
 508         spin_lock(&kset->list_lock);
 509         list_for_each(entry,&kset->list) {
 510                 struct kobject * k = to_kobj(entry);
 511                 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
 512                         ret = kobject_get(k);
 513                         break;
 514                 }
 515         }
 516         spin_unlock(&kset->list_lock);
 517         return ret;
 518 }
 519
 520
 521 void subsystem_init(struct subsystem * s)
 522 {
 523         init_rwsem(&s->rwsem);
 524         kset_init(&s->kset);
 525 }
 526
 527 /**
 528  *      subsystem_register - register a subsystem.
 529  *      @s:     the subsystem we're registering.
 530  *
 531  *      Once we register the subsystem, we want to make sure that
 532  *      the kset points back to this subsystem for correct usage of
 533  *      the rwsem.
 534  */
 535
 536 int subsystem_register(struct subsystem * s)
 537 {
 538         int error;
 539
 540         subsystem_init(s);
 541         pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
 542
 543         if (!(error = kset_add(&s->kset))) {
 544                 if (!s->kset.subsys)
 545                         s->kset.subsys = s;
 546         }
 547         return error;
 548 }
 549
 550 void subsystem_unregister(struct subsystem * s)
 551 {
 552         pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
 553         kset_unregister(&s->kset);
 554 }
 555
 556
 557 /**
 558  *      subsystem_create_file - export sysfs attribute file.
 559  *      @s:     subsystem.
 560  *      @a:     subsystem attribute descriptor.
 561  */
 562
 563 int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
 564 {
 565         int error = 0;
 566         if (subsys_get(s)) {
 567                 error = sysfs_create_file(&s->kset.kobj,&a->attr);
 568                 subsys_put(s);
 569         }
 570         return error;
 571 }
 572
 573
 574 /**
 575  *      subsystem_remove_file - remove sysfs attribute file.
 576  *      @s:     subsystem.
 577  *      @a:     attribute desciptor.
 578  */
 579 #if 0
 580 void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
 581 {
 582         if (subsys_get(s)) {
 583                 sysfs_remove_file(&s->kset.kobj,&a->attr);
 584                 subsys_put(s);
 585         }
 586 }
 587 #endif  /*  0  */
 588
 589 EXPORT_SYMBOL(kobject_init);
 590 EXPORT_SYMBOL(kobject_register);
 591 EXPORT_SYMBOL(kobject_unregister);
 592 EXPORT_SYMBOL(kobject_get);
 593 EXPORT_SYMBOL(kobject_put);
 594 EXPORT_SYMBOL(kobject_add);
 595 EXPORT_SYMBOL(kobject_del);
 596
 597 EXPORT_SYMBOL(kset_register);
 598 EXPORT_SYMBOL(kset_unregister);
 599
 600 EXPORT_SYMBOL(subsystem_register);
 601 EXPORT_SYMBOL(subsystem_unregister);
 602 EXPORT_SYMBOL(subsys_create_file);