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
 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  *      @shadow_parent: sysfs directory to add to.
 162  */
 163
 164 int kobject_shadow_add(struct kobject * kobj, struct dentry *shadow_parent)
 165 {
 166         int error = 0;
 167         struct kobject * parent;
 168
 169         if (!(kobj = kobject_get(kobj)))
 170                 return -ENOENT;
 171         if (!kobj->k_name)
 172                 kobj->k_name = kobj->name;
 173         if (!kobj->k_name) {
 174                 pr_debug("kobject attempted to be registered with no name!\n");
 175                 WARN_ON(1);
 176                 return -EINVAL;
 177         }
 178         parent = kobject_get(kobj->parent);
 179
 180         pr_debug("kobject %s: registering. parent: %s, set: %s\n",
 181                  kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>",
 182                  kobj->kset ? kobj->kset->kobj.name : "<NULL>" );
 183
 184         if (kobj->kset) {
 185                 spin_lock(&kobj->kset->list_lock);
 186
 187                 if (!parent)
 188                         parent = kobject_get(&kobj->kset->kobj);
 189
 190                 list_add_tail(&kobj->entry,&kobj->kset->list);
 191                 spin_unlock(&kobj->kset->list_lock);
 192         }
 193         kobj->parent = parent;
 194
 195         error = create_dir(kobj, shadow_parent);
 196         if (error) {
 197                 /* unlink does the kobject_put() for us */
 198                 unlink(kobj);
 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  *      kobject_add - add an object to the hierarchy.
 218  *      @kobj:  object.
 219  */
 220 int kobject_add(struct kobject * kobj)
 221 {
 222         return kobject_shadow_add(kobj, NULL);
 223 }
 224
 225
 226 /**
 227  *      kobject_register - initialize and add an object.
 228  *      @kobj:  object in question.
 229  */
 230
 231 int kobject_register(struct kobject * kobj)
 232 {
 233         int error = -EINVAL;
 234         if (kobj) {
 235                 kobject_init(kobj);
 236                 error = kobject_add(kobj);
 237                 if (!error)
 238                         kobject_uevent(kobj, KOBJ_ADD);
 239         }
 240         return error;
 241 }
 242
 243
 244 /**
 245  *      kobject_set_name - Set the name of an object
 246  *      @kobj:  object.
 247  *      @fmt:   format string used to build the name
 248  *
 249  *      If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
 250  *      string that @kobj->k_name points to. Otherwise, use the static
 251  *      @kobj->name array.
 252  */
 253 int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
 254 {
 255         int error = 0;
 256         int limit = KOBJ_NAME_LEN;
 257         int need;
 258         va_list args;
 259         char * name;
 260
 261         /*
 262          * First, try the static array
 263          */
 264         va_start(args,fmt);
 265         need = vsnprintf(kobj->name,limit,fmt,args);
 266         va_end(args);
 267         if (need < limit)
 268                 name = kobj->name;
 269         else {
 270                 /*
 271                  * Need more space? Allocate it and try again
 272                  */
 273                 limit = need + 1;
 274                 name = kmalloc(limit,GFP_KERNEL);
 275                 if (!name) {
 276                         error = -ENOMEM;
 277                         goto Done;
 278                 }
 279                 va_start(args,fmt);
 280                 need = vsnprintf(name,limit,fmt,args);
 281                 va_end(args);
 282
 283                 /* Still? Give up. */
 284                 if (need >= limit) {
 285                         kfree(name);
 286                         error = -EFAULT;
 287                         goto Done;
 288                 }
 289         }
 290
 291         /* Free the old name, if necessary. */
 292         if (kobj->k_name && kobj->k_name != kobj->name)
 293                 kfree(kobj->k_name);
 294
 295         /* Now, set the new name */
 296         kobj->k_name = name;
 297  Done:
 298         return error;
 299 }
 300
 301 EXPORT_SYMBOL(kobject_set_name);
 302
 303
 304 /**
 305  *      kobject_rename - change the name of an object
 306  *      @kobj:  object in question.
 307  *      @new_name: object's new name
 308  */
 309
 310 int kobject_rename(struct kobject * kobj, const char *new_name)
 311 {
 312         int error = 0;
 313
 314         kobj = kobject_get(kobj);
 315         if (!kobj)
 316                 return -EINVAL;
 317         if (!kobj->parent)
 318                 return -EINVAL;
 319         error = sysfs_rename_dir(kobj, kobj->parent->dentry, new_name);
 320         kobject_put(kobj);
 321
 322         return error;
 323 }
 324
 325 /**
 326  *      kobject_rename - change the name of an object
 327  *      @kobj:  object in question.
 328  *      @new_name: object's new name
 329  */
 330
 331 int kobject_shadow_rename(struct kobject * kobj, struct dentry *new_parent,
 332                           const char *new_name)
 333 {
 334         int error = 0;
 335
 336         kobj = kobject_get(kobj);
 337         if (!kobj)
 338                 return -EINVAL;
 339         error = sysfs_rename_dir(kobj, new_parent, new_name);
 340         kobject_put(kobj);
 341
 342         return error;
 343 }
 344
 345 /**
 346  *      kobject_move - move object to another parent
 347  *      @kobj:  object in question.
 348  *      @new_parent: object's new parent (can be NULL)
 349  */
 350
 351 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 352 {
 353         int error;
 354         struct kobject *old_parent;
 355         const char *devpath = NULL;
 356         char *devpath_string = NULL;
 357         char *envp[2];
 358
 359         kobj = kobject_get(kobj);
 360         if (!kobj)
 361                 return -EINVAL;
 362         new_parent = kobject_get(new_parent);
 363         if (!new_parent) {
 364                 if (kobj->kset)
 365                         new_parent = kobject_get(&kobj->kset->kobj);
 366         }
 367         /* old object path */
 368         devpath = kobject_get_path(kobj, GFP_KERNEL);
 369         if (!devpath) {
 370                 error = -ENOMEM;
 371                 goto out;
 372         }
 373         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 374         if (!devpath_string) {
 375                 error = -ENOMEM;
 376                 goto out;
 377         }
 378         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 379         envp[0] = devpath_string;
 380         envp[1] = NULL;
 381         error = sysfs_move_dir(kobj, new_parent);
 382         if (error)
 383                 goto out;
 384         old_parent = kobj->parent;
 385         kobj->parent = new_parent;
 386         kobject_put(old_parent);
 387         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 388 out:
 389         kobject_put(kobj);
 390         kfree(devpath_string);
 391         kfree(devpath);
 392         return error;
 393 }
 394
 395 /**
 396  *      kobject_del - unlink kobject from hierarchy.
 397  *      @kobj:  object.
 398  */
 399
 400 void kobject_del(struct kobject * kobj)
 401 {
 402         if (!kobj)
 403                 return;
 404         sysfs_remove_dir(kobj);
 405         unlink(kobj);
 406 }
 407
 408 /**
 409  *      kobject_unregister - remove object from hierarchy and decrement refcount.
 410  *      @kobj:  object going away.
 411  */
 412
 413 void kobject_unregister(struct kobject * kobj)
 414 {
 415         if (!kobj)
 416                 return;
 417         pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
 418         kobject_uevent(kobj, KOBJ_REMOVE);
 419         kobject_del(kobj);
 420         kobject_put(kobj);
 421 }
 422
 423 /**
 424  *      kobject_get - increment refcount for object.
 425  *      @kobj:  object.
 426  */
 427
 428 struct kobject * kobject_get(struct kobject * kobj)
 429 {
 430         if (kobj)
 431                 kref_get(&kobj->kref);
 432         return kobj;
 433 }
 434
 435 /**
 436  *      kobject_cleanup - free kobject resources.
 437  *      @kobj:  object.
 438  */
 439
 440 void kobject_cleanup(struct kobject * kobj)
 441 {
 442         struct kobj_type * t = get_ktype(kobj);
 443         struct kset * s = kobj->kset;
 444         struct kobject * parent = kobj->parent;
 445
 446         pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
 447         if (kobj->k_name != kobj->name)
 448                 kfree(kobj->k_name);
 449         kobj->k_name = NULL;
 450         if (t && t->release)
 451                 t->release(kobj);
 452         if (s)
 453                 kset_put(s);
 454         kobject_put(parent);
 455 }
 456
 457 static void kobject_release(struct kref *kref)
 458 {
 459         kobject_cleanup(container_of(kref, struct kobject, kref));
 460 }
 461
 462 /**
 463  *      kobject_put - decrement refcount for object.
 464  *      @kobj:  object.
 465  *
 466  *      Decrement the refcount, and if 0, call kobject_cleanup().
 467  */
 468 void kobject_put(struct kobject * kobj)
 469 {
 470         if (kobj)
 471                 kref_put(&kobj->kref, kobject_release);
 472 }
 473
 474
 475 static void dir_release(struct kobject *kobj)
 476 {
 477         kfree(kobj);
 478 }
 479
 480 static struct kobj_type dir_ktype = {
 481         .release        = dir_release,
 482         .sysfs_ops      = NULL,
 483         .default_attrs  = NULL,
 484 };
 485
 486 /**
 487  *      kobject_add_dir - add sub directory of object.
 488  *      @parent:        object in which a directory is created.
 489  *      @name:  directory name.
 490  *
 491  *      Add a plain directory object as child of given object.
 492  */
 493 struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
 494 {
 495         struct kobject *k;
 496         int ret;
 497
 498         if (!parent)
 499                 return NULL;
 500
 501         k = kzalloc(sizeof(*k), GFP_KERNEL);
 502         if (!k)
 503                 return NULL;
 504
 505         k->parent = parent;
 506         k->ktype = &dir_ktype;
 507         kobject_set_name(k, name);
 508         ret = kobject_register(k);
 509         if (ret < 0) {
 510                 printk(KERN_WARNING "kobject_add_dir: "
 511                         "kobject_register error: %d\n", ret);
 512                 kobject_del(k);
 513                 return NULL;
 514         }
 515
 516         return k;
 517 }
 518
 519 /**
 520  *      kset_init - initialize a kset for use
 521  *      @k:     kset
 522  */
 523
 524 void kset_init(struct kset * k)
 525 {
 526         kobject_init(&k->kobj);
 527         INIT_LIST_HEAD(&k->list);
 528         spin_lock_init(&k->list_lock);
 529 }
 530
 531
 532 /**
 533  *      kset_add - add a kset object to the hierarchy.
 534  *      @k:     kset.
 535  *
 536  *      Simply, this adds the kset's embedded kobject to the
 537  *      hierarchy.
 538  *      We also try to make sure that the kset's embedded kobject
 539  *      has a parent before it is added. We only care if the embedded
 540  *      kobject is not part of a kset itself, since kobject_add()
 541  *      assigns a parent in that case.
 542  *      If that is the case, and the kset has a controlling subsystem,
 543  *      then we set the kset's parent to be said subsystem.
 544  */
 545
 546 int kset_add(struct kset * k)
 547 {
 548         if (!k->kobj.parent && !k->kobj.kset && k->subsys)
 549                 k->kobj.parent = &k->subsys->kset.kobj;
 550
 551         return kobject_add(&k->kobj);
 552 }
 553
 554
 555 /**
 556  *      kset_register - initialize and add a kset.
 557  *      @k:     kset.
 558  */
 559
 560 int kset_register(struct kset * k)
 561 {
 562         if (!k)
 563                 return -EINVAL;
 564         kset_init(k);
 565         return kset_add(k);
 566 }
 567
 568
 569 /**
 570  *      kset_unregister - remove a kset.
 571  *      @k:     kset.
 572  */
 573
 574 void kset_unregister(struct kset * k)
 575 {
 576         if (!k)
 577                 return;
 578         kobject_unregister(&k->kobj);
 579 }
 580
 581
 582 /**
 583  *      kset_find_obj - search for object in kset.
 584  *      @kset:  kset we're looking in.
 585  *      @name:  object's name.
 586  *
 587  *      Lock kset via @kset->subsys, and iterate over @kset->list,
 588  *      looking for a matching kobject. If matching object is found
 589  *      take a reference and return the object.
 590  */
 591
 592 struct kobject * kset_find_obj(struct kset * kset, const char * name)
 593 {
 594         struct list_head * entry;
 595         struct kobject * ret = NULL;
 596
 597         spin_lock(&kset->list_lock);
 598         list_for_each(entry,&kset->list) {
 599                 struct kobject * k = to_kobj(entry);
 600                 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
 601                         ret = kobject_get(k);
 602                         break;
 603                 }
 604         }
 605         spin_unlock(&kset->list_lock);
 606         return ret;
 607 }
 608
 609
 610 void subsystem_init(struct subsystem * s)
 611 {
 612         init_rwsem(&s->rwsem);
 613         kset_init(&s->kset);
 614 }
 615
 616 /**
 617  *      subsystem_register - register a subsystem.
 618  *      @s:     the subsystem we're registering.
 619  *
 620  *      Once we register the subsystem, we want to make sure that
 621  *      the kset points back to this subsystem for correct usage of
 622  *      the rwsem.
 623  */
 624
 625 int subsystem_register(struct subsystem * s)
 626 {
 627         int error;
 628
 629         if (!s)
 630                 return -EINVAL;
 631
 632         subsystem_init(s);
 633         pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
 634
 635         if (!(error = kset_add(&s->kset))) {
 636                 if (!s->kset.subsys)
 637                         s->kset.subsys = s;
 638         }
 639         return error;
 640 }
 641
 642 void subsystem_unregister(struct subsystem * s)
 643 {
 644         if (!s)
 645                 return;
 646         pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
 647         kset_unregister(&s->kset);
 648 }
 649
 650
 651 /**
 652  *      subsystem_create_file - export sysfs attribute file.
 653  *      @s:     subsystem.
 654  *      @a:     subsystem attribute descriptor.
 655  */
 656
 657 int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
 658 {
 659         int error = 0;
 660
 661         if (!s || !a)
 662                 return -EINVAL;
 663
 664         if (subsys_get(s)) {
 665                 error = sysfs_create_file(&s->kset.kobj,&a->attr);
 666                 subsys_put(s);
 667         }
 668         return error;
 669 }
 670
 671
 672 /**
 673  *      subsystem_remove_file - remove sysfs attribute file.
 674  *      @s:     subsystem.
 675  *      @a:     attribute desciptor.
 676  */
 677 #if 0
 678 void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
 679 {
 680         if (subsys_get(s)) {
 681                 sysfs_remove_file(&s->kset.kobj,&a->attr);
 682                 subsys_put(s);
 683         }
 684 }
 685 #endif  /*  0  */
 686
 687 EXPORT_SYMBOL(kobject_init);
 688 EXPORT_SYMBOL(kobject_register);
 689 EXPORT_SYMBOL(kobject_unregister);
 690 EXPORT_SYMBOL(kobject_get);
 691 EXPORT_SYMBOL(kobject_put);
 692 EXPORT_SYMBOL(kobject_add);
 693 EXPORT_SYMBOL(kobject_del);
 694
 695 EXPORT_SYMBOL(kset_register);
 696 EXPORT_SYMBOL(kset_unregister);
 697
 698 EXPORT_SYMBOL(subsystem_register);
 699 EXPORT_SYMBOL(subsystem_unregister);
 700 EXPORT_SYMBOL(subsys_create_file);