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  * Copyright (c) 2006-2007 Greg Kroah-Hartman <greg@kroah.com>
   6  * Copyright (c) 2006-2007 Novell Inc.
   7  *
   8  * This file is released under the GPLv2.
   9  *
  10  *
  11  * Please see the file Documentation/kobject.txt for critical information
  12  * about using the kobject interface.
  13  */
  14
  15 #include <linux/kobject.h>
  16 #include <linux/string.h>
  17 #include <linux/module.h>
  18 #include <linux/stat.h>
  19 #include <linux/slab.h>
  20
  21 /**
  22  *      populate_dir - populate directory with attributes.
  23  *      @kobj:  object we're working on.
  24  *
  25  *      Most subsystems have a set of default attributes that
  26  *      are associated with an object that registers with them.
  27  *      This is a helper called during object registration that
  28  *      loops through the default attributes of the subsystem
  29  *      and creates attributes files for them in sysfs.
  30  *
  31  */
  32
  33 static int populate_dir(struct kobject * kobj)
  34 {
  35         struct kobj_type * t = get_ktype(kobj);
  36         struct attribute * attr;
  37         int error = 0;
  38         int i;
  39
  40         if (t && t->default_attrs) {
  41                 for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
  42                         if ((error = sysfs_create_file(kobj,attr)))
  43                                 break;
  44                 }
  45         }
  46         return error;
  47 }
  48
  49 static int create_dir(struct kobject * kobj)
  50 {
  51         int error = 0;
  52         if (kobject_name(kobj)) {
  53                 error = sysfs_create_dir(kobj);
  54                 if (!error) {
  55                         if ((error = populate_dir(kobj)))
  56                                 sysfs_remove_dir(kobj);
  57                 }
  58         }
  59         return error;
  60 }
  61
  62 static inline struct kobject * to_kobj(struct list_head * entry)
  63 {
  64         return container_of(entry,struct kobject,entry);
  65 }
  66
  67 static int get_kobj_path_length(struct kobject *kobj)
  68 {
  69         int length = 1;
  70         struct kobject * parent = kobj;
  71
  72         /* walk up the ancestors until we hit the one pointing to the
  73          * root.
  74          * Add 1 to strlen for leading '/' of each level.
  75          */
  76         do {
  77                 if (kobject_name(parent) == NULL)
  78                         return 0;
  79                 length += strlen(kobject_name(parent)) + 1;
  80                 parent = parent->parent;
  81         } while (parent);
  82         return length;
  83 }
  84
  85 static void fill_kobj_path(struct kobject *kobj, char *path, int length)
  86 {
  87         struct kobject * parent;
  88
  89         --length;
  90         for (parent = kobj; parent; parent = parent->parent) {
  91                 int cur = strlen(kobject_name(parent));
  92                 /* back up enough to print this name with '/' */
  93                 length -= cur;
  94                 strncpy (path + length, kobject_name(parent), cur);
  95                 *(path + --length) = '/';
  96         }
  97
  98         pr_debug("%s: path = '%s'\n",__FUNCTION__,path);
  99 }
 100
 101 /**
 102  * kobject_get_path - generate and return the path associated with a given kobj and kset pair.
 103  *
 104  * @kobj:       kobject in question, with which to build the path
 105  * @gfp_mask:   the allocation type used to allocate the path
 106  *
 107  * The result must be freed by the caller with kfree().
 108  */
 109 char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
 110 {
 111         char *path;
 112         int len;
 113
 114         len = get_kobj_path_length(kobj);
 115         if (len == 0)
 116                 return NULL;
 117         path = kzalloc(len, gfp_mask);
 118         if (!path)
 119                 return NULL;
 120         fill_kobj_path(kobj, path, len);
 121
 122         return path;
 123 }
 124 EXPORT_SYMBOL_GPL(kobject_get_path);
 125
 126 /**
 127  *      kobject_init - initialize object.
 128  *      @kobj:  object in question.
 129  */
 130 void kobject_init(struct kobject * kobj)
 131 {
 132         if (!kobj)
 133                 return;
 134         kref_init(&kobj->kref);
 135         INIT_LIST_HEAD(&kobj->entry);
 136         kobj->kset = kset_get(kobj->kset);
 137 }
 138
 139
 140 /**
 141  *      unlink - remove kobject from kset list.
 142  *      @kobj:  kobject.
 143  *
 144  *      Remove the kobject from the kset list and decrement
 145  *      its parent's refcount.
 146  *      This is separated out, so we can use it in both
 147  *      kobject_del() and kobject_add() on error.
 148  */
 149
 150 static void unlink(struct kobject * kobj)
 151 {
 152         if (kobj->kset) {
 153                 spin_lock(&kobj->kset->list_lock);
 154                 list_del_init(&kobj->entry);
 155                 spin_unlock(&kobj->kset->list_lock);
 156         }
 157         kobject_put(kobj);
 158 }
 159
 160 /**
 161  *      kobject_add - add an object to the hierarchy.
 162  *      @kobj:  object.
 163  */
 164
 165 int kobject_add(struct kobject * kobj)
 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                 kobject_set_name(kobj, "NO_NAME");
 174         if (!*kobj->k_name) {
 175                 pr_debug("kobject attempted to be registered with no name!\n");
 176                 WARN_ON(1);
 177                 kobject_put(kobj);
 178                 return -EINVAL;
 179         }
 180         parent = kobject_get(kobj->parent);
 181
 182         pr_debug("kobject %s: registering. parent: %s, set: %s\n",
 183                  kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>",
 184                  kobj->kset ? kobject_name(&kobj->kset->kobj) : "<NULL>" );
 185
 186         if (kobj->kset) {
 187                 spin_lock(&kobj->kset->list_lock);
 188
 189                 if (!parent)
 190                         parent = kobject_get(&kobj->kset->kobj);
 191
 192                 list_add_tail(&kobj->entry,&kobj->kset->list);
 193                 spin_unlock(&kobj->kset->list_lock);
 194                 kobj->parent = parent;
 195         }
 196
 197         error = create_dir(kobj);
 198         if (error) {
 199                 /* unlink does the kobject_put() for us */
 200                 unlink(kobj);
 201                 kobject_put(parent);
 202
 203                 /* be noisy on error issues */
 204                 if (error == -EEXIST)
 205                         printk(KERN_ERR "kobject_add failed for %s with "
 206                                "-EEXIST, don't try to register things with "
 207                                "the same name in the same directory.\n",
 208                                kobject_name(kobj));
 209                 else
 210                         printk(KERN_ERR "kobject_add failed for %s (%d)\n",
 211                                kobject_name(kobj), error);
 212                 dump_stack();
 213         }
 214
 215         return error;
 216 }
 217
 218 /**
 219  *      kobject_register - initialize and add an object.
 220  *      @kobj:  object in question.
 221  */
 222
 223 int kobject_register(struct kobject * kobj)
 224 {
 225         int error = -EINVAL;
 226         if (kobj) {
 227                 kobject_init(kobj);
 228                 error = kobject_add(kobj);
 229                 if (!error)
 230                         kobject_uevent(kobj, KOBJ_ADD);
 231         }
 232         return error;
 233 }
 234
 235
 236 /**
 237  *      kobject_set_name - Set the name of an object
 238  *      @kobj:  object.
 239  *      @fmt:   format string used to build the name
 240  *
 241  *      If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
 242  *      string that @kobj->k_name points to. Otherwise, use the static
 243  *      @kobj->name array.
 244  */
 245 int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
 246 {
 247         int error = 0;
 248         int limit;
 249         int need;
 250         va_list args;
 251         char *name;
 252
 253         /* find out how big a buffer we need */
 254         name = kmalloc(1024, GFP_KERNEL);
 255         if (!name) {
 256                 error = -ENOMEM;
 257                 goto done;
 258         }
 259         va_start(args, fmt);
 260         need = vsnprintf(name, 1024, fmt, args);
 261         va_end(args);
 262         kfree(name);
 263
 264         /* Allocate the new space and copy the string in */
 265         limit = need + 1;
 266         name = kmalloc(limit, GFP_KERNEL);
 267         if (!name) {
 268                 error = -ENOMEM;
 269                 goto done;
 270         }
 271         va_start(args, fmt);
 272         need = vsnprintf(name, limit, fmt, args);
 273         va_end(args);
 274
 275         /* something wrong with the string we copied? */
 276         if (need >= limit) {
 277                 kfree(name);
 278                 error = -EFAULT;
 279                 goto done;
 280         }
 281
 282         /* Free the old name, if necessary. */
 283         kfree(kobj->k_name);
 284
 285         /* Now, set the new name */
 286         kobj->k_name = name;
 287 done:
 288         return error;
 289 }
 290 EXPORT_SYMBOL(kobject_set_name);
 291
 292 /**
 293  *      kobject_rename - change the name of an object
 294  *      @kobj:  object in question.
 295  *      @new_name: object's new name
 296  */
 297
 298 int kobject_rename(struct kobject * kobj, const char *new_name)
 299 {
 300         int error = 0;
 301         const char *devpath = NULL;
 302         char *devpath_string = NULL;
 303         char *envp[2];
 304
 305         kobj = kobject_get(kobj);
 306         if (!kobj)
 307                 return -EINVAL;
 308         if (!kobj->parent)
 309                 return -EINVAL;
 310
 311         /* see if this name is already in use */
 312         if (kobj->kset) {
 313                 struct kobject *temp_kobj;
 314                 temp_kobj = kset_find_obj(kobj->kset, new_name);
 315                 if (temp_kobj) {
 316                         printk(KERN_WARNING "kobject '%s' cannot be renamed "
 317                                "to '%s' as '%s' is already in existence.\n",
 318                                kobject_name(kobj), new_name, new_name);
 319                         kobject_put(temp_kobj);
 320                         return -EINVAL;
 321                 }
 322         }
 323
 324         devpath = kobject_get_path(kobj, GFP_KERNEL);
 325         if (!devpath) {
 326                 error = -ENOMEM;
 327                 goto out;
 328         }
 329         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 330         if (!devpath_string) {
 331                 error = -ENOMEM;
 332                 goto out;
 333         }
 334         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 335         envp[0] = devpath_string;
 336         envp[1] = NULL;
 337         /* Note : if we want to send the new name alone, not the full path,
 338          * we could probably use kobject_name(kobj); */
 339
 340         error = sysfs_rename_dir(kobj, new_name);
 341
 342         /* This function is mostly/only used for network interface.
 343          * Some hotplug package track interfaces by their name and
 344          * therefore want to know when the name is changed by the user. */
 345         if (!error)
 346                 kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 347
 348 out:
 349         kfree(devpath_string);
 350         kfree(devpath);
 351         kobject_put(kobj);
 352
 353         return error;
 354 }
 355
 356 /**
 357  *      kobject_move - move object to another parent
 358  *      @kobj:  object in question.
 359  *      @new_parent: object's new parent (can be NULL)
 360  */
 361
 362 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 363 {
 364         int error;
 365         struct kobject *old_parent;
 366         const char *devpath = NULL;
 367         char *devpath_string = NULL;
 368         char *envp[2];
 369
 370         kobj = kobject_get(kobj);
 371         if (!kobj)
 372                 return -EINVAL;
 373         new_parent = kobject_get(new_parent);
 374         if (!new_parent) {
 375                 if (kobj->kset)
 376                         new_parent = kobject_get(&kobj->kset->kobj);
 377         }
 378         /* old object path */
 379         devpath = kobject_get_path(kobj, GFP_KERNEL);
 380         if (!devpath) {
 381                 error = -ENOMEM;
 382                 goto out;
 383         }
 384         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 385         if (!devpath_string) {
 386                 error = -ENOMEM;
 387                 goto out;
 388         }
 389         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 390         envp[0] = devpath_string;
 391         envp[1] = NULL;
 392         error = sysfs_move_dir(kobj, new_parent);
 393         if (error)
 394                 goto out;
 395         old_parent = kobj->parent;
 396         kobj->parent = new_parent;
 397         new_parent = NULL;
 398         kobject_put(old_parent);
 399         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 400 out:
 401         kobject_put(new_parent);
 402         kobject_put(kobj);
 403         kfree(devpath_string);
 404         kfree(devpath);
 405         return error;
 406 }
 407
 408 /**
 409  *      kobject_del - unlink kobject from hierarchy.
 410  *      @kobj:  object.
 411  */
 412
 413 void kobject_del(struct kobject * kobj)
 414 {
 415         if (!kobj)
 416                 return;
 417         sysfs_remove_dir(kobj);
 418         unlink(kobj);
 419 }
 420
 421 /**
 422  *      kobject_unregister - remove object from hierarchy and decrement refcount.
 423  *      @kobj:  object going away.
 424  */
 425
 426 void kobject_unregister(struct kobject * kobj)
 427 {
 428         if (!kobj)
 429                 return;
 430         pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
 431         kobject_uevent(kobj, KOBJ_REMOVE);
 432         kobject_del(kobj);
 433         kobject_put(kobj);
 434 }
 435
 436 /**
 437  *      kobject_get - increment refcount for object.
 438  *      @kobj:  object.
 439  */
 440
 441 struct kobject * kobject_get(struct kobject * kobj)
 442 {
 443         if (kobj)
 444                 kref_get(&kobj->kref);
 445         return kobj;
 446 }
 447
 448 /**
 449  *      kobject_cleanup - free kobject resources.
 450  *      @kobj:  object.
 451  */
 452
 453 void kobject_cleanup(struct kobject * kobj)
 454 {
 455         struct kobj_type * t = get_ktype(kobj);
 456         struct kset * s = kobj->kset;
 457         struct kobject * parent = kobj->parent;
 458         const char *name = kobj->k_name;
 459
 460         pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
 461         if (t && t->release) {
 462                 t->release(kobj);
 463                 /* If we have a release function, we can guess that this was
 464                  * not a statically allocated kobject, so we should be safe to
 465                  * free the name */
 466                 kfree(name);
 467         }
 468         if (s)
 469                 kset_put(s);
 470         kobject_put(parent);
 471 }
 472
 473 static void kobject_release(struct kref *kref)
 474 {
 475         kobject_cleanup(container_of(kref, struct kobject, kref));
 476 }
 477
 478 /**
 479  *      kobject_put - decrement refcount for object.
 480  *      @kobj:  object.
 481  *
 482  *      Decrement the refcount, and if 0, call kobject_cleanup().
 483  */
 484 void kobject_put(struct kobject * kobj)
 485 {
 486         if (kobj)
 487                 kref_put(&kobj->kref, kobject_release);
 488 }
 489
 490
 491 static void dir_release(struct kobject *kobj)
 492 {
 493         kfree(kobj);
 494 }
 495
 496 static struct kobj_type dir_ktype = {
 497         .release        = dir_release,
 498         .sysfs_ops      = NULL,
 499         .default_attrs  = NULL,
 500 };
 501
 502 /**
 503  *      kobject_kset_add_dir - add sub directory of object.
 504  *      @kset:          kset the directory is belongs to.
 505  *      @parent:        object in which a directory is created.
 506  *      @name:  directory name.
 507  *
 508  *      Add a plain directory object as child of given object.
 509  */
 510 struct kobject *kobject_kset_add_dir(struct kset *kset,
 511                                      struct kobject *parent, const char *name)
 512 {
 513         struct kobject *k;
 514         int ret;
 515
 516         if (!parent)
 517                 return NULL;
 518
 519         k = kzalloc(sizeof(*k), GFP_KERNEL);
 520         if (!k)
 521                 return NULL;
 522
 523         k->kset = kset;
 524         k->parent = parent;
 525         k->ktype = &dir_ktype;
 526         kobject_set_name(k, name);
 527         ret = kobject_register(k);
 528         if (ret < 0) {
 529                 printk(KERN_WARNING "%s: kobject_register error: %d\n",
 530                         __func__, ret);
 531                 kobject_del(k);
 532                 return NULL;
 533         }
 534
 535         return k;
 536 }
 537
 538 /**
 539  *      kobject_add_dir - add sub directory of object.
 540  *      @parent:        object in which a directory is created.
 541  *      @name:  directory name.
 542  *
 543  *      Add a plain directory object as child of given object.
 544  */
 545 struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
 546 {
 547         return kobject_kset_add_dir(NULL, parent, name);
 548 }
 549
 550 /**
 551  *      kset_init - initialize a kset for use
 552  *      @k:     kset
 553  */
 554
 555 void kset_init(struct kset * k)
 556 {
 557         kobject_init(&k->kobj);
 558         INIT_LIST_HEAD(&k->list);
 559         spin_lock_init(&k->list_lock);
 560 }
 561
 562
 563 /**
 564  *      kset_add - add a kset object to the hierarchy.
 565  *      @k:     kset.
 566  */
 567
 568 int kset_add(struct kset * k)
 569 {
 570         return kobject_add(&k->kobj);
 571 }
 572
 573
 574 /**
 575  *      kset_register - initialize and add a kset.
 576  *      @k:     kset.
 577  */
 578
 579 int kset_register(struct kset * k)
 580 {
 581         int err;
 582
 583         if (!k)
 584                 return -EINVAL;
 585
 586         kset_init(k);
 587         err = kset_add(k);
 588         if (err)
 589                 return err;
 590         kobject_uevent(&k->kobj, KOBJ_ADD);
 591         return 0;
 592 }
 593
 594
 595 /**
 596  *      kset_unregister - remove a kset.
 597  *      @k:     kset.
 598  */
 599
 600 void kset_unregister(struct kset * k)
 601 {
 602         if (!k)
 603                 return;
 604         kobject_unregister(&k->kobj);
 605 }
 606
 607
 608 /**
 609  *      kset_find_obj - search for object in kset.
 610  *      @kset:  kset we're looking in.
 611  *      @name:  object's name.
 612  *
 613  *      Lock kset via @kset->subsys, and iterate over @kset->list,
 614  *      looking for a matching kobject. If matching object is found
 615  *      take a reference and return the object.
 616  */
 617
 618 struct kobject * kset_find_obj(struct kset * kset, const char * name)
 619 {
 620         struct list_head * entry;
 621         struct kobject * ret = NULL;
 622
 623         spin_lock(&kset->list_lock);
 624         list_for_each(entry,&kset->list) {
 625                 struct kobject * k = to_kobj(entry);
 626                 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
 627                         ret = kobject_get(k);
 628                         break;
 629                 }
 630         }
 631         spin_unlock(&kset->list_lock);
 632         return ret;
 633 }
 634
 635 int subsystem_register(struct kset *s)
 636 {
 637         return kset_register(s);
 638 }
 639
 640 void subsystem_unregister(struct kset *s)
 641 {
 642         kset_unregister(s);
 643 }
 644
 645 /**
 646  *      subsystem_create_file - export sysfs attribute file.
 647  *      @s:     subsystem.
 648  *      @a:     subsystem attribute descriptor.
 649  */
 650
 651 int subsys_create_file(struct kset *s, struct subsys_attribute *a)
 652 {
 653         int error = 0;
 654
 655         if (!s || !a)
 656                 return -EINVAL;
 657
 658         if (kset_get(s)) {
 659                 error = sysfs_create_file(&s->kobj, &a->attr);
 660                 kset_put(s);
 661         }
 662         return error;
 663 }
 664
 665 EXPORT_SYMBOL(kobject_init);
 666 EXPORT_SYMBOL(kobject_register);
 667 EXPORT_SYMBOL(kobject_unregister);
 668 EXPORT_SYMBOL(kobject_get);
 669 EXPORT_SYMBOL(kobject_put);
 670 EXPORT_SYMBOL(kobject_add);
 671 EXPORT_SYMBOL(kobject_del);
 672
 673 EXPORT_SYMBOL(kset_register);
 674 EXPORT_SYMBOL(kset_unregister);
 675
 676 EXPORT_SYMBOL(subsystem_register);
 677 EXPORT_SYMBOL(subsystem_unregister);
 678 EXPORT_SYMBOL(subsys_create_file);