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         if (!kobj)
 130                 return;
 131         kref_init(&kobj->kref);
 132         INIT_LIST_HEAD(&kobj->entry);
 133         init_waitqueue_head(&kobj->poll);
 134         kobj->kset = kset_get(kobj->kset);
 135 }
 136
 137
 138 /**
 139  *      unlink - remove kobject from kset list.
 140  *      @kobj:  kobject.
 141  *
 142  *      Remove the kobject from the kset list and decrement
 143  *      its parent's refcount.
 144  *      This is separated out, so we can use it in both
 145  *      kobject_del() and kobject_add() on error.
 146  */
 147
 148 static void unlink(struct kobject * kobj)
 149 {
 150         if (kobj->kset) {
 151                 spin_lock(&kobj->kset->list_lock);
 152                 list_del_init(&kobj->entry);
 153                 spin_unlock(&kobj->kset->list_lock);
 154         }
 155         kobject_put(kobj);
 156 }
 157
 158 /**
 159  *      kobject_add - add an object to the hierarchy.
 160  *      @kobj:  object.
 161  */
 162
 163 int kobject_add(struct kobject * kobj)
 164 {
 165         int error = 0;
 166         struct kobject * parent;
 167
 168         if (!(kobj = kobject_get(kobj)))
 169                 return -ENOENT;
 170         if (!kobj->k_name)
 171                 kobj->k_name = kobj->name;
 172         if (!kobj->k_name) {
 173                 pr_debug("kobject attempted to be registered with no name!\n");
 174                 WARN_ON(1);
 175                 return -EINVAL;
 176         }
 177         parent = kobject_get(kobj->parent);
 178
 179         pr_debug("kobject %s: registering. parent: %s, set: %s\n",
 180                  kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>",
 181                  kobj->kset ? kobj->kset->kobj.name : "<NULL>" );
 182
 183         if (kobj->kset) {
 184                 spin_lock(&kobj->kset->list_lock);
 185
 186                 if (!parent)
 187                         parent = kobject_get(&kobj->kset->kobj);
 188
 189                 list_add_tail(&kobj->entry,&kobj->kset->list);
 190                 spin_unlock(&kobj->kset->list_lock);
 191         }
 192         kobj->parent = parent;
 193
 194         error = create_dir(kobj);
 195         if (error) {
 196                 /* unlink does the kobject_put() for us */
 197                 unlink(kobj);
 198                 if (parent)
 199                         kobject_put(parent);
 200
 201                 /* be noisy on error issues */
 202                 if (error == -EEXIST)
 203                         printk("kobject_add failed for %s with -EEXIST, "
 204                                "don't try to register things with the "
 205                                "same name in the same directory.\n",
 206                                kobject_name(kobj));
 207                 else
 208                         printk("kobject_add failed for %s (%d)\n",
 209                                kobject_name(kobj), error);
 210                  dump_stack();
 211         }
 212
 213         return error;
 214 }
 215
 216
 217 /**
 218  *      kobject_register - initialize and add an object.
 219  *      @kobj:  object in question.
 220  */
 221
 222 int kobject_register(struct kobject * kobj)
 223 {
 224         int error = -EINVAL;
 225         if (kobj) {
 226                 kobject_init(kobj);
 227                 error = kobject_add(kobj);
 228                 if (!error)
 229                         kobject_uevent(kobj, KOBJ_ADD);
 230         }
 231         return error;
 232 }
 233
 234
 235 /**
 236  *      kobject_set_name - Set the name of an object
 237  *      @kobj:  object.
 238  *      @fmt:   format string used to build the name
 239  *
 240  *      If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
 241  *      string that @kobj->k_name points to. Otherwise, use the static
 242  *      @kobj->name array.
 243  */
 244 int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
 245 {
 246         int error = 0;
 247         int limit = KOBJ_NAME_LEN;
 248         int need;
 249         va_list args;
 250         char * name;
 251
 252         /*
 253          * First, try the static array
 254          */
 255         va_start(args,fmt);
 256         need = vsnprintf(kobj->name,limit,fmt,args);
 257         va_end(args);
 258         if (need < limit)
 259                 name = kobj->name;
 260         else {
 261                 /*
 262                  * Need more space? Allocate it and try again
 263                  */
 264                 limit = need + 1;
 265                 name = kmalloc(limit,GFP_KERNEL);
 266                 if (!name) {
 267                         error = -ENOMEM;
 268                         goto Done;
 269                 }
 270                 va_start(args,fmt);
 271                 need = vsnprintf(name,limit,fmt,args);
 272                 va_end(args);
 273
 274                 /* Still? Give up. */
 275                 if (need >= limit) {
 276                         kfree(name);
 277                         error = -EFAULT;
 278                         goto Done;
 279                 }
 280         }
 281
 282         /* Free the old name, if necessary. */
 283         if (kobj->k_name && kobj->k_name != kobj->name)
 284                 kfree(kobj->k_name);
 285
 286         /* Now, set the new name */
 287         kobj->k_name = name;
 288  Done:
 289         return error;
 290 }
 291
 292 EXPORT_SYMBOL(kobject_set_name);
 293
 294
 295 /**
 296  *      kobject_rename - change the name of an object
 297  *      @kobj:  object in question.
 298  *      @new_name: object's new name
 299  */
 300
 301 int kobject_rename(struct kobject * kobj, const char *new_name)
 302 {
 303         int error = 0;
 304
 305         kobj = kobject_get(kobj);
 306         if (!kobj)
 307                 return -EINVAL;
 308         error = sysfs_rename_dir(kobj, new_name);
 309         kobject_put(kobj);
 310
 311         return error;
 312 }
 313
 314 /**
 315  *      kobject_move - move object to another parent
 316  *      @kobj:  object in question.
 317  *      @new_parent: object's new parent
 318  */
 319
 320 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 321 {
 322         int error;
 323         struct kobject *old_parent;
 324         const char *devpath = NULL;
 325         char *devpath_string = NULL;
 326         char *envp[2];
 327
 328         kobj = kobject_get(kobj);
 329         if (!kobj)
 330                 return -EINVAL;
 331         new_parent = kobject_get(new_parent);
 332         if (!new_parent) {
 333                 error = -EINVAL;
 334                 goto out;
 335         }
 336         /* old object path */
 337         devpath = kobject_get_path(kobj, GFP_KERNEL);
 338         if (!devpath) {
 339                 error = -ENOMEM;
 340                 goto out;
 341         }
 342         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 343         if (!devpath_string) {
 344                 error = -ENOMEM;
 345                 goto out;
 346         }
 347         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 348         envp[0] = devpath_string;
 349         envp[1] = NULL;
 350         error = sysfs_move_dir(kobj, new_parent);
 351         if (error)
 352                 goto out;
 353         old_parent = kobj->parent;
 354         kobj->parent = new_parent;
 355         kobject_put(old_parent);
 356         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 357 out:
 358         kobject_put(kobj);
 359         kfree(devpath_string);
 360         kfree(devpath);
 361         return error;
 362 }
 363
 364 /**
 365  *      kobject_del - unlink kobject from hierarchy.
 366  *      @kobj:  object.
 367  */
 368
 369 void kobject_del(struct kobject * kobj)
 370 {
 371         if (!kobj)
 372                 return;
 373         sysfs_remove_dir(kobj);
 374         unlink(kobj);
 375 }
 376
 377 /**
 378  *      kobject_unregister - remove object from hierarchy and decrement refcount.
 379  *      @kobj:  object going away.
 380  */
 381
 382 void kobject_unregister(struct kobject * kobj)
 383 {
 384         if (!kobj)
 385                 return;
 386         pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
 387         kobject_uevent(kobj, KOBJ_REMOVE);
 388         kobject_del(kobj);
 389         kobject_put(kobj);
 390 }
 391
 392 /**
 393  *      kobject_get - increment refcount for object.
 394  *      @kobj:  object.
 395  */
 396
 397 struct kobject * kobject_get(struct kobject * kobj)
 398 {
 399         if (kobj)
 400                 kref_get(&kobj->kref);
 401         return kobj;
 402 }
 403
 404 /**
 405  *      kobject_cleanup - free kobject resources.
 406  *      @kobj:  object.
 407  */
 408
 409 void kobject_cleanup(struct kobject * kobj)
 410 {
 411         struct kobj_type * t = get_ktype(kobj);
 412         struct kset * s = kobj->kset;
 413         struct kobject * parent = kobj->parent;
 414
 415         pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
 416         if (kobj->k_name != kobj->name)
 417                 kfree(kobj->k_name);
 418         kobj->k_name = NULL;
 419         if (t && t->release)
 420                 t->release(kobj);
 421         if (s)
 422                 kset_put(s);
 423         if (parent)
 424                 kobject_put(parent);
 425 }
 426
 427 static void kobject_release(struct kref *kref)
 428 {
 429         kobject_cleanup(container_of(kref, struct kobject, kref));
 430 }
 431
 432 /**
 433  *      kobject_put - decrement refcount for object.
 434  *      @kobj:  object.
 435  *
 436  *      Decrement the refcount, and if 0, call kobject_cleanup().
 437  */
 438 void kobject_put(struct kobject * kobj)
 439 {
 440         if (kobj)
 441                 kref_put(&kobj->kref, kobject_release);
 442 }
 443
 444
 445 static void dir_release(struct kobject *kobj)
 446 {
 447         kfree(kobj);
 448 }
 449
 450 static struct kobj_type dir_ktype = {
 451         .release        = dir_release,
 452         .sysfs_ops      = NULL,
 453         .default_attrs  = NULL,
 454 };
 455
 456 /**
 457  *      kobject_add_dir - add sub directory of object.
 458  *      @parent:        object in which a directory is created.
 459  *      @name:  directory name.
 460  *
 461  *      Add a plain directory object as child of given object.
 462  */
 463 struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
 464 {
 465         struct kobject *k;
 466         int ret;
 467
 468         if (!parent)
 469                 return NULL;
 470
 471         k = kzalloc(sizeof(*k), GFP_KERNEL);
 472         if (!k)
 473                 return NULL;
 474
 475         k->parent = parent;
 476         k->ktype = &dir_ktype;
 477         kobject_set_name(k, name);
 478         ret = kobject_register(k);
 479         if (ret < 0) {
 480                 printk(KERN_WARNING "kobject_add_dir: "
 481                         "kobject_register error: %d\n", ret);
 482                 kobject_del(k);
 483                 return NULL;
 484         }
 485
 486         return k;
 487 }
 488
 489 /**
 490  *      kset_init - initialize a kset for use
 491  *      @k:     kset
 492  */
 493
 494 void kset_init(struct kset * k)
 495 {
 496         kobject_init(&k->kobj);
 497         INIT_LIST_HEAD(&k->list);
 498         spin_lock_init(&k->list_lock);
 499 }
 500
 501
 502 /**
 503  *      kset_add - add a kset object to the hierarchy.
 504  *      @k:     kset.
 505  *
 506  *      Simply, this adds the kset's embedded kobject to the
 507  *      hierarchy.
 508  *      We also try to make sure that the kset's embedded kobject
 509  *      has a parent before it is added. We only care if the embedded
 510  *      kobject is not part of a kset itself, since kobject_add()
 511  *      assigns a parent in that case.
 512  *      If that is the case, and the kset has a controlling subsystem,
 513  *      then we set the kset's parent to be said subsystem.
 514  */
 515
 516 int kset_add(struct kset * k)
 517 {
 518         if (!k->kobj.parent && !k->kobj.kset && k->subsys)
 519                 k->kobj.parent = &k->subsys->kset.kobj;
 520
 521         return kobject_add(&k->kobj);
 522 }
 523
 524
 525 /**
 526  *      kset_register - initialize and add a kset.
 527  *      @k:     kset.
 528  */
 529
 530 int kset_register(struct kset * k)
 531 {
 532         if (!k)
 533                 return -EINVAL;
 534         kset_init(k);
 535         return kset_add(k);
 536 }
 537
 538
 539 /**
 540  *      kset_unregister - remove a kset.
 541  *      @k:     kset.
 542  */
 543
 544 void kset_unregister(struct kset * k)
 545 {
 546         if (!k)
 547                 return;
 548         kobject_unregister(&k->kobj);
 549 }
 550
 551
 552 /**
 553  *      kset_find_obj - search for object in kset.
 554  *      @kset:  kset we're looking in.
 555  *      @name:  object's name.
 556  *
 557  *      Lock kset via @kset->subsys, and iterate over @kset->list,
 558  *      looking for a matching kobject. If matching object is found
 559  *      take a reference and return the object.
 560  */
 561
 562 struct kobject * kset_find_obj(struct kset * kset, const char * name)
 563 {
 564         struct list_head * entry;
 565         struct kobject * ret = NULL;
 566
 567         spin_lock(&kset->list_lock);
 568         list_for_each(entry,&kset->list) {
 569                 struct kobject * k = to_kobj(entry);
 570                 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
 571                         ret = kobject_get(k);
 572                         break;
 573                 }
 574         }
 575         spin_unlock(&kset->list_lock);
 576         return ret;
 577 }
 578
 579
 580 void subsystem_init(struct subsystem * s)
 581 {
 582         init_rwsem(&s->rwsem);
 583         kset_init(&s->kset);
 584 }
 585
 586 /**
 587  *      subsystem_register - register a subsystem.
 588  *      @s:     the subsystem we're registering.
 589  *
 590  *      Once we register the subsystem, we want to make sure that
 591  *      the kset points back to this subsystem for correct usage of
 592  *      the rwsem.
 593  */
 594
 595 int subsystem_register(struct subsystem * s)
 596 {
 597         int error;
 598
 599         if (!s)
 600                 return -EINVAL;
 601
 602         subsystem_init(s);
 603         pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
 604
 605         if (!(error = kset_add(&s->kset))) {
 606                 if (!s->kset.subsys)
 607                         s->kset.subsys = s;
 608         }
 609         return error;
 610 }
 611
 612 void subsystem_unregister(struct subsystem * s)
 613 {
 614         if (!s)
 615                 return;
 616         pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
 617         kset_unregister(&s->kset);
 618 }
 619
 620
 621 /**
 622  *      subsystem_create_file - export sysfs attribute file.
 623  *      @s:     subsystem.
 624  *      @a:     subsystem attribute descriptor.
 625  */
 626
 627 int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
 628 {
 629         int error = 0;
 630
 631         if (!s || !a)
 632                 return -EINVAL;
 633
 634         if (subsys_get(s)) {
 635                 error = sysfs_create_file(&s->kset.kobj,&a->attr);
 636                 subsys_put(s);
 637         }
 638         return error;
 639 }
 640
 641
 642 /**
 643  *      subsystem_remove_file - remove sysfs attribute file.
 644  *      @s:     subsystem.
 645  *      @a:     attribute desciptor.
 646  */
 647 #if 0
 648 void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
 649 {
 650         if (subsys_get(s)) {
 651                 sysfs_remove_file(&s->kset.kobj,&a->attr);
 652                 subsys_put(s);
 653         }
 654 }
 655 #endif  /*  0  */
 656
 657 EXPORT_SYMBOL(kobject_init);
 658 EXPORT_SYMBOL(kobject_register);
 659 EXPORT_SYMBOL(kobject_unregister);
 660 EXPORT_SYMBOL(kobject_get);
 661 EXPORT_SYMBOL(kobject_put);
 662 EXPORT_SYMBOL(kobject_add);
 663 EXPORT_SYMBOL(kobject_del);
 664
 665 EXPORT_SYMBOL(kset_register);
 666 EXPORT_SYMBOL(kset_unregister);
 667
 668 EXPORT_SYMBOL(subsystem_register);
 669 EXPORT_SYMBOL(subsystem_unregister);
 670 EXPORT_SYMBOL(subsys_create_file);