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                 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_move - move object to another parent
 315  *      @kobj:  object in question.
 316  *      @new_parent: object's new parent (can be NULL)
 317  */
 318
 319 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 320 {
 321         int error;
 322         struct kobject *old_parent;
 323         const char *devpath = NULL;
 324         char *devpath_string = NULL;
 325         char *envp[2];
 326
 327         kobj = kobject_get(kobj);
 328         if (!kobj)
 329                 return -EINVAL;
 330         new_parent = kobject_get(new_parent);
 331         if (!new_parent) {
 332                 if (kobj->kset)
 333                         new_parent = kobject_get(&kobj->kset->kobj);
 334         }
 335         /* old object path */
 336         devpath = kobject_get_path(kobj, GFP_KERNEL);
 337         if (!devpath) {
 338                 error = -ENOMEM;
 339                 goto out;
 340         }
 341         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 342         if (!devpath_string) {
 343                 error = -ENOMEM;
 344                 goto out;
 345         }
 346         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 347         envp[0] = devpath_string;
 348         envp[1] = NULL;
 349         error = sysfs_move_dir(kobj, new_parent);
 350         if (error)
 351                 goto out;
 352         old_parent = kobj->parent;
 353         kobj->parent = new_parent;
 354         kobject_put(old_parent);
 355         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 356 out:
 357         kobject_put(kobj);
 358         kfree(devpath_string);
 359         kfree(devpath);
 360         return error;
 361 }
 362
 363 /**
 364  *      kobject_del - unlink kobject from hierarchy.
 365  *      @kobj:  object.
 366  */
 367
 368 void kobject_del(struct kobject * kobj)
 369 {
 370         if (!kobj)
 371                 return;
 372         sysfs_remove_dir(kobj);
 373         unlink(kobj);
 374 }
 375
 376 /**
 377  *      kobject_unregister - remove object from hierarchy and decrement refcount.
 378  *      @kobj:  object going away.
 379  */
 380
 381 void kobject_unregister(struct kobject * kobj)
 382 {
 383         if (!kobj)
 384                 return;
 385         pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
 386         kobject_uevent(kobj, KOBJ_REMOVE);
 387         kobject_del(kobj);
 388         kobject_put(kobj);
 389 }
 390
 391 /**
 392  *      kobject_get - increment refcount for object.
 393  *      @kobj:  object.
 394  */
 395
 396 struct kobject * kobject_get(struct kobject * kobj)
 397 {
 398         if (kobj)
 399                 kref_get(&kobj->kref);
 400         return kobj;
 401 }
 402
 403 /**
 404  *      kobject_cleanup - free kobject resources.
 405  *      @kobj:  object.
 406  */
 407
 408 void kobject_cleanup(struct kobject * kobj)
 409 {
 410         struct kobj_type * t = get_ktype(kobj);
 411         struct kset * s = kobj->kset;
 412         struct kobject * parent = kobj->parent;
 413
 414         pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
 415         if (kobj->k_name != kobj->name)
 416                 kfree(kobj->k_name);
 417         kobj->k_name = NULL;
 418         if (t && t->release)
 419                 t->release(kobj);
 420         if (s)
 421                 kset_put(s);
 422         kobject_put(parent);
 423 }
 424
 425 static void kobject_release(struct kref *kref)
 426 {
 427         kobject_cleanup(container_of(kref, struct kobject, kref));
 428 }
 429
 430 /**
 431  *      kobject_put - decrement refcount for object.
 432  *      @kobj:  object.
 433  *
 434  *      Decrement the refcount, and if 0, call kobject_cleanup().
 435  */
 436 void kobject_put(struct kobject * kobj)
 437 {
 438         if (kobj)
 439                 kref_put(&kobj->kref, kobject_release);
 440 }
 441
 442
 443 static void dir_release(struct kobject *kobj)
 444 {
 445         kfree(kobj);
 446 }
 447
 448 static struct kobj_type dir_ktype = {
 449         .release        = dir_release,
 450         .sysfs_ops      = NULL,
 451         .default_attrs  = NULL,
 452 };
 453
 454 /**
 455  *      kobject_add_dir - add sub directory of object.
 456  *      @parent:        object in which a directory is created.
 457  *      @name:  directory name.
 458  *
 459  *      Add a plain directory object as child of given object.
 460  */
 461 struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
 462 {
 463         struct kobject *k;
 464         int ret;
 465
 466         if (!parent)
 467                 return NULL;
 468
 469         k = kzalloc(sizeof(*k), GFP_KERNEL);
 470         if (!k)
 471                 return NULL;
 472
 473         k->parent = parent;
 474         k->ktype = &dir_ktype;
 475         kobject_set_name(k, name);
 476         ret = kobject_register(k);
 477         if (ret < 0) {
 478                 printk(KERN_WARNING "kobject_add_dir: "
 479                         "kobject_register error: %d\n", ret);
 480                 kobject_del(k);
 481                 return NULL;
 482         }
 483
 484         return k;
 485 }
 486
 487 /**
 488  *      kset_init - initialize a kset for use
 489  *      @k:     kset
 490  */
 491
 492 void kset_init(struct kset * k)
 493 {
 494         kobject_init(&k->kobj);
 495         INIT_LIST_HEAD(&k->list);
 496         spin_lock_init(&k->list_lock);
 497 }
 498
 499
 500 /**
 501  *      kset_add - add a kset object to the hierarchy.
 502  *      @k:     kset.
 503  *
 504  *      Simply, this adds the kset's embedded kobject to the
 505  *      hierarchy.
 506  *      We also try to make sure that the kset's embedded kobject
 507  *      has a parent before it is added. We only care if the embedded
 508  *      kobject is not part of a kset itself, since kobject_add()
 509  *      assigns a parent in that case.
 510  *      If that is the case, and the kset has a controlling subsystem,
 511  *      then we set the kset's parent to be said subsystem.
 512  */
 513
 514 int kset_add(struct kset * k)
 515 {
 516         if (!k->kobj.parent && !k->kobj.kset && k->subsys)
 517                 k->kobj.parent = &k->subsys->kset.kobj;
 518
 519         return kobject_add(&k->kobj);
 520 }
 521
 522
 523 /**
 524  *      kset_register - initialize and add a kset.
 525  *      @k:     kset.
 526  */
 527
 528 int kset_register(struct kset * k)
 529 {
 530         if (!k)
 531                 return -EINVAL;
 532         kset_init(k);
 533         return kset_add(k);
 534 }
 535
 536
 537 /**
 538  *      kset_unregister - remove a kset.
 539  *      @k:     kset.
 540  */
 541
 542 void kset_unregister(struct kset * k)
 543 {
 544         if (!k)
 545                 return;
 546         kobject_unregister(&k->kobj);
 547 }
 548
 549
 550 /**
 551  *      kset_find_obj - search for object in kset.
 552  *      @kset:  kset we're looking in.
 553  *      @name:  object's name.
 554  *
 555  *      Lock kset via @kset->subsys, and iterate over @kset->list,
 556  *      looking for a matching kobject. If matching object is found
 557  *      take a reference and return the object.
 558  */
 559
 560 struct kobject * kset_find_obj(struct kset * kset, const char * name)
 561 {
 562         struct list_head * entry;
 563         struct kobject * ret = NULL;
 564
 565         spin_lock(&kset->list_lock);
 566         list_for_each(entry,&kset->list) {
 567                 struct kobject * k = to_kobj(entry);
 568                 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
 569                         ret = kobject_get(k);
 570                         break;
 571                 }
 572         }
 573         spin_unlock(&kset->list_lock);
 574         return ret;
 575 }
 576
 577
 578 void subsystem_init(struct subsystem * s)
 579 {
 580         init_rwsem(&s->rwsem);
 581         kset_init(&s->kset);
 582 }
 583
 584 /**
 585  *      subsystem_register - register a subsystem.
 586  *      @s:     the subsystem we're registering.
 587  *
 588  *      Once we register the subsystem, we want to make sure that
 589  *      the kset points back to this subsystem for correct usage of
 590  *      the rwsem.
 591  */
 592
 593 int subsystem_register(struct subsystem * s)
 594 {
 595         int error;
 596
 597         if (!s)
 598                 return -EINVAL;
 599
 600         subsystem_init(s);
 601         pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
 602
 603         if (!(error = kset_add(&s->kset))) {
 604                 if (!s->kset.subsys)
 605                         s->kset.subsys = s;
 606         }
 607         return error;
 608 }
 609
 610 void subsystem_unregister(struct subsystem * s)
 611 {
 612         if (!s)
 613                 return;
 614         pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
 615         kset_unregister(&s->kset);
 616 }
 617
 618
 619 /**
 620  *      subsystem_create_file - export sysfs attribute file.
 621  *      @s:     subsystem.
 622  *      @a:     subsystem attribute descriptor.
 623  */
 624
 625 int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
 626 {
 627         int error = 0;
 628
 629         if (!s || !a)
 630                 return -EINVAL;
 631
 632         if (subsys_get(s)) {
 633                 error = sysfs_create_file(&s->kset.kobj,&a->attr);
 634                 subsys_put(s);
 635         }
 636         return error;
 637 }
 638
 639
 640 /**
 641  *      subsystem_remove_file - remove sysfs attribute file.
 642  *      @s:     subsystem.
 643  *      @a:     attribute desciptor.
 644  */
 645 #if 0
 646 void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
 647 {
 648         if (subsys_get(s)) {
 649                 sysfs_remove_file(&s->kset.kobj,&a->attr);
 650                 subsys_put(s);
 651         }
 652 }
 653 #endif  /*  0  */
 654
 655 EXPORT_SYMBOL(kobject_init);
 656 EXPORT_SYMBOL(kobject_register);
 657 EXPORT_SYMBOL(kobject_unregister);
 658 EXPORT_SYMBOL(kobject_get);
 659 EXPORT_SYMBOL(kobject_put);
 660 EXPORT_SYMBOL(kobject_add);
 661 EXPORT_SYMBOL(kobject_del);
 662
 663 EXPORT_SYMBOL(kset_register);
 664 EXPORT_SYMBOL(kset_unregister);
 665
 666 EXPORT_SYMBOL(subsystem_register);
 667 EXPORT_SYMBOL(subsystem_unregister);
 668 EXPORT_SYMBOL(subsys_create_file);