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, struct dentry *shadow_parent)
  48 {
  49         int error = 0;
  50         if (kobject_name(kobj)) {
  51                 error = sysfs_create_dir(kobj, shadow_parent);
  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 and kset pair.
 101  *
 102  * @kobj:       kobject in question, with which to build the path
 103  * @gfp_mask:   the allocation type used to allocate the path
 104  *
 105  * The result must be freed by the caller with kfree().
 106  */
 107 char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
 108 {
 109         char *path;
 110         int len;
 111
 112         len = get_kobj_path_length(kobj);
 113         if (len == 0)
 114                 return NULL;
 115         path = kzalloc(len, gfp_mask);
 116         if (!path)
 117                 return NULL;
 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         if (!kobj)
 131                 return;
 132         kref_init(&kobj->kref);
 133         INIT_LIST_HEAD(&kobj->entry);
 134         init_waitqueue_head(&kobj->poll);
 135         kobj->kset = kset_get(kobj->kset);
 136 }
 137
 138
 139 /**
 140  *      unlink - remove kobject from kset list.
 141  *      @kobj:  kobject.
 142  *
 143  *      Remove the kobject from the kset list and decrement
 144  *      its parent's refcount.
 145  *      This is separated out, so we can use it in both
 146  *      kobject_del() and kobject_add() on error.
 147  */
 148
 149 static void unlink(struct kobject * kobj)
 150 {
 151         if (kobj->kset) {
 152                 spin_lock(&kobj->kset->list_lock);
 153                 list_del_init(&kobj->entry);
 154                 spin_unlock(&kobj->kset->list_lock);
 155         }
 156         kobject_put(kobj);
 157 }
 158
 159 /**
 160  *      kobject_add - add an object to the hierarchy.
 161  *      @kobj:  object.
 162  *      @shadow_parent: sysfs directory to add to.
 163  */
 164
 165 int kobject_shadow_add(struct kobject * kobj, struct dentry *shadow_parent)
 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                 kobj->k_name = kobj->name;
 174         if (!*kobj->k_name) {
 175                 pr_debug("kobject attempted to be registered with no name!\n");
 176                 WARN_ON(1);
 177                 return -EINVAL;
 178         }
 179         parent = kobject_get(kobj->parent);
 180
 181         pr_debug("kobject %s: registering. parent: %s, set: %s\n",
 182                  kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>",
 183                  kobj->kset ? kobj->kset->kobj.name : "<NULL>" );
 184
 185         if (kobj->kset) {
 186                 spin_lock(&kobj->kset->list_lock);
 187
 188                 if (!parent)
 189                         parent = kobject_get(&kobj->kset->kobj);
 190
 191                 list_add_tail(&kobj->entry,&kobj->kset->list);
 192                 spin_unlock(&kobj->kset->list_lock);
 193         }
 194         kobj->parent = parent;
 195
 196         error = create_dir(kobj, shadow_parent);
 197         if (error) {
 198                 /* unlink does the kobject_put() for us */
 199                 unlink(kobj);
 200                 kobject_put(parent);
 201
 202                 /* be noisy on error issues */
 203                 if (error == -EEXIST)
 204                         printk("kobject_add failed for %s with -EEXIST, "
 205                                "don't try to register things with the "
 206                                "same name in the same directory.\n",
 207                                kobject_name(kobj));
 208                 else
 209                         printk("kobject_add failed for %s (%d)\n",
 210                                kobject_name(kobj), error);
 211                  dump_stack();
 212         }
 213
 214         return error;
 215 }
 216
 217 /**
 218  *      kobject_add - add an object to the hierarchy.
 219  *      @kobj:  object.
 220  */
 221 int kobject_add(struct kobject * kobj)
 222 {
 223         return kobject_shadow_add(kobj, NULL);
 224 }
 225
 226
 227 /**
 228  *      kobject_register - initialize and add an object.
 229  *      @kobj:  object in question.
 230  */
 231
 232 int kobject_register(struct kobject * kobj)
 233 {
 234         int error = -EINVAL;
 235         if (kobj) {
 236                 kobject_init(kobj);
 237                 error = kobject_add(kobj);
 238                 if (!error)
 239                         kobject_uevent(kobj, KOBJ_ADD);
 240         }
 241         return error;
 242 }
 243
 244
 245 /**
 246  *      kobject_set_name - Set the name of an object
 247  *      @kobj:  object.
 248  *      @fmt:   format string used to build the name
 249  *
 250  *      If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
 251  *      string that @kobj->k_name points to. Otherwise, use the static
 252  *      @kobj->name array.
 253  */
 254 int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
 255 {
 256         int error = 0;
 257         int limit = KOBJ_NAME_LEN;
 258         int need;
 259         va_list args;
 260         char * name;
 261
 262         /*
 263          * First, try the static array
 264          */
 265         va_start(args,fmt);
 266         need = vsnprintf(kobj->name,limit,fmt,args);
 267         va_end(args);
 268         if (need < limit)
 269                 name = kobj->name;
 270         else {
 271                 /*
 272                  * Need more space? Allocate it and try again
 273                  */
 274                 limit = need + 1;
 275                 name = kmalloc(limit,GFP_KERNEL);
 276                 if (!name) {
 277                         error = -ENOMEM;
 278                         goto Done;
 279                 }
 280                 va_start(args,fmt);
 281                 need = vsnprintf(name,limit,fmt,args);
 282                 va_end(args);
 283
 284                 /* Still? Give up. */
 285                 if (need >= limit) {
 286                         kfree(name);
 287                         error = -EFAULT;
 288                         goto Done;
 289                 }
 290         }
 291
 292         /* Free the old name, if necessary. */
 293         if (kobj->k_name && kobj->k_name != kobj->name)
 294                 kfree(kobj->k_name);
 295
 296         /* Now, set the new name */
 297         kobj->k_name = name;
 298  Done:
 299         return error;
 300 }
 301
 302 EXPORT_SYMBOL(kobject_set_name);
 303
 304
 305 /**
 306  *      kobject_rename - change the name of an object
 307  *      @kobj:  object in question.
 308  *      @new_name: object's new name
 309  */
 310
 311 int kobject_rename(struct kobject * kobj, const char *new_name)
 312 {
 313         int error = 0;
 314
 315         kobj = kobject_get(kobj);
 316         if (!kobj)
 317                 return -EINVAL;
 318         if (!kobj->parent)
 319                 return -EINVAL;
 320         error = sysfs_rename_dir(kobj, kobj->parent->dentry, new_name);
 321         kobject_put(kobj);
 322
 323         return error;
 324 }
 325
 326 /**
 327  *      kobject_rename - change the name of an object
 328  *      @kobj:  object in question.
 329  *      @new_parent: object's new parent
 330  *      @new_name: object's new name
 331  */
 332
 333 int kobject_shadow_rename(struct kobject * kobj, struct dentry *new_parent,
 334                           const char *new_name)
 335 {
 336         int error = 0;
 337
 338         kobj = kobject_get(kobj);
 339         if (!kobj)
 340                 return -EINVAL;
 341         error = sysfs_rename_dir(kobj, new_parent, new_name);
 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         kobject_put(old_parent);
 389         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 390 out:
 391         kobject_put(kobj);
 392         kfree(devpath_string);
 393         kfree(devpath);
 394         return error;
 395 }
 396
 397 /**
 398  *      kobject_del - unlink kobject from hierarchy.
 399  *      @kobj:  object.
 400  */
 401
 402 void kobject_del(struct kobject * kobj)
 403 {
 404         if (!kobj)
 405                 return;
 406         sysfs_remove_dir(kobj);
 407         unlink(kobj);
 408 }
 409
 410 /**
 411  *      kobject_unregister - remove object from hierarchy and decrement refcount.
 412  *      @kobj:  object going away.
 413  */
 414
 415 void kobject_unregister(struct kobject * kobj)
 416 {
 417         if (!kobj)
 418                 return;
 419         pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
 420         kobject_uevent(kobj, KOBJ_REMOVE);
 421         kobject_del(kobj);
 422         kobject_put(kobj);
 423 }
 424
 425 /**
 426  *      kobject_get - increment refcount for object.
 427  *      @kobj:  object.
 428  */
 429
 430 struct kobject * kobject_get(struct kobject * kobj)
 431 {
 432         if (kobj)
 433                 kref_get(&kobj->kref);
 434         return kobj;
 435 }
 436
 437 /**
 438  *      kobject_cleanup - free kobject resources.
 439  *      @kobj:  object.
 440  */
 441
 442 void kobject_cleanup(struct kobject * kobj)
 443 {
 444         struct kobj_type * t = get_ktype(kobj);
 445         struct kset * s = kobj->kset;
 446         struct kobject * parent = kobj->parent;
 447
 448         pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
 449         if (kobj->k_name != kobj->name)
 450                 kfree(kobj->k_name);
 451         kobj->k_name = NULL;
 452         if (t && t->release)
 453                 t->release(kobj);
 454         if (s)
 455                 kset_put(s);
 456         kobject_put(parent);
 457 }
 458
 459 static void kobject_release(struct kref *kref)
 460 {
 461         kobject_cleanup(container_of(kref, struct kobject, kref));
 462 }
 463
 464 /**
 465  *      kobject_put - decrement refcount for object.
 466  *      @kobj:  object.
 467  *
 468  *      Decrement the refcount, and if 0, call kobject_cleanup().
 469  */
 470 void kobject_put(struct kobject * kobj)
 471 {
 472         if (kobj)
 473                 kref_put(&kobj->kref, kobject_release);
 474 }
 475
 476
 477 static void dir_release(struct kobject *kobj)
 478 {
 479         kfree(kobj);
 480 }
 481
 482 static struct kobj_type dir_ktype = {
 483         .release        = dir_release,
 484         .sysfs_ops      = NULL,
 485         .default_attrs  = NULL,
 486 };
 487
 488 /**
 489  *      kobject_add_dir - add sub directory of object.
 490  *      @parent:        object in which a directory is created.
 491  *      @name:  directory name.
 492  *
 493  *      Add a plain directory object as child of given object.
 494  */
 495 struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
 496 {
 497         struct kobject *k;
 498         int ret;
 499
 500         if (!parent)
 501                 return NULL;
 502
 503         k = kzalloc(sizeof(*k), GFP_KERNEL);
 504         if (!k)
 505                 return NULL;
 506
 507         k->parent = parent;
 508         k->ktype = &dir_ktype;
 509         kobject_set_name(k, name);
 510         ret = kobject_register(k);
 511         if (ret < 0) {
 512                 printk(KERN_WARNING "kobject_add_dir: "
 513                         "kobject_register error: %d\n", ret);
 514                 kobject_del(k);
 515                 return NULL;
 516         }
 517
 518         return k;
 519 }
 520
 521 /**
 522  *      kset_init - initialize a kset for use
 523  *      @k:     kset
 524  */
 525
 526 void kset_init(struct kset * k)
 527 {
 528         kobject_init(&k->kobj);
 529         INIT_LIST_HEAD(&k->list);
 530         spin_lock_init(&k->list_lock);
 531 }
 532
 533
 534 /**
 535  *      kset_add - add a kset object to the hierarchy.
 536  *      @k:     kset.
 537  *
 538  *      Simply, this adds the kset's embedded kobject to the
 539  *      hierarchy.
 540  *      We also try to make sure that the kset's embedded kobject
 541  *      has a parent before it is added. We only care if the embedded
 542  *      kobject is not part of a kset itself, since kobject_add()
 543  *      assigns a parent in that case.
 544  *      If that is the case, and the kset has a controlling subsystem,
 545  *      then we set the kset's parent to be said subsystem.
 546  */
 547
 548 int kset_add(struct kset * k)
 549 {
 550         if (!k->kobj.parent && !k->kobj.kset && k->subsys)
 551                 k->kobj.parent = &k->subsys->kset.kobj;
 552
 553         return kobject_add(&k->kobj);
 554 }
 555
 556
 557 /**
 558  *      kset_register - initialize and add a kset.
 559  *      @k:     kset.
 560  */
 561
 562 int kset_register(struct kset * k)
 563 {
 564         if (!k)
 565                 return -EINVAL;
 566         kset_init(k);
 567         return kset_add(k);
 568 }
 569
 570
 571 /**
 572  *      kset_unregister - remove a kset.
 573  *      @k:     kset.
 574  */
 575
 576 void kset_unregister(struct kset * k)
 577 {
 578         if (!k)
 579                 return;
 580         kobject_unregister(&k->kobj);
 581 }
 582
 583
 584 /**
 585  *      kset_find_obj - search for object in kset.
 586  *      @kset:  kset we're looking in.
 587  *      @name:  object's name.
 588  *
 589  *      Lock kset via @kset->subsys, and iterate over @kset->list,
 590  *      looking for a matching kobject. If matching object is found
 591  *      take a reference and return the object.
 592  */
 593
 594 struct kobject * kset_find_obj(struct kset * kset, const char * name)
 595 {
 596         struct list_head * entry;
 597         struct kobject * ret = NULL;
 598
 599         spin_lock(&kset->list_lock);
 600         list_for_each(entry,&kset->list) {
 601                 struct kobject * k = to_kobj(entry);
 602                 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
 603                         ret = kobject_get(k);
 604                         break;
 605                 }
 606         }
 607         spin_unlock(&kset->list_lock);
 608         return ret;
 609 }
 610
 611
 612 void subsystem_init(struct subsystem * s)
 613 {
 614         init_rwsem(&s->rwsem);
 615         kset_init(&s->kset);
 616 }
 617
 618 /**
 619  *      subsystem_register - register a subsystem.
 620  *      @s:     the subsystem we're registering.
 621  *
 622  *      Once we register the subsystem, we want to make sure that
 623  *      the kset points back to this subsystem for correct usage of
 624  *      the rwsem.
 625  */
 626
 627 int subsystem_register(struct subsystem * s)
 628 {
 629         int error;
 630
 631         if (!s)
 632                 return -EINVAL;
 633
 634         subsystem_init(s);
 635         pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
 636
 637         if (!(error = kset_add(&s->kset))) {
 638                 if (!s->kset.subsys)
 639                         s->kset.subsys = s;
 640         }
 641         return error;
 642 }
 643
 644 void subsystem_unregister(struct subsystem * s)
 645 {
 646         if (!s)
 647                 return;
 648         pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
 649         kset_unregister(&s->kset);
 650 }
 651
 652
 653 /**
 654  *      subsystem_create_file - export sysfs attribute file.
 655  *      @s:     subsystem.
 656  *      @a:     subsystem attribute descriptor.
 657  */
 658
 659 int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
 660 {
 661         int error = 0;
 662
 663         if (!s || !a)
 664                 return -EINVAL;
 665
 666         if (subsys_get(s)) {
 667                 error = sysfs_create_file(&s->kset.kobj,&a->attr);
 668                 subsys_put(s);
 669         }
 670         return error;
 671 }
 672
 673
 674 /**
 675  *      subsystem_remove_file - remove sysfs attribute file.
 676  *      @s:     subsystem.
 677  *      @a:     attribute desciptor.
 678  */
 679 #if 0
 680 void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
 681 {
 682         if (subsys_get(s)) {
 683                 sysfs_remove_file(&s->kset.kobj,&a->attr);
 684                 subsys_put(s);
 685         }
 686 }
 687 #endif  /*  0  */
 688
 689 EXPORT_SYMBOL(kobject_init);
 690 EXPORT_SYMBOL(kobject_register);
 691 EXPORT_SYMBOL(kobject_unregister);
 692 EXPORT_SYMBOL(kobject_get);
 693 EXPORT_SYMBOL(kobject_put);
 694 EXPORT_SYMBOL(kobject_add);
 695 EXPORT_SYMBOL(kobject_del);
 696
 697 EXPORT_SYMBOL(kset_register);
 698 EXPORT_SYMBOL(kset_unregister);
 699
 700 EXPORT_SYMBOL(subsystem_register);
 701 EXPORT_SYMBOL(subsystem_unregister);
 702 EXPORT_SYMBOL(subsys_create_file);