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         devpath = kobject_get_path(kobj, GFP_KERNEL);
 312         if (!devpath) {
 313                 error = -ENOMEM;
 314                 goto out;
 315         }
 316         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 317         if (!devpath_string) {
 318                 error = -ENOMEM;
 319                 goto out;
 320         }
 321         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 322         envp[0] = devpath_string;
 323         envp[1] = NULL;
 324         /* Note : if we want to send the new name alone, not the full path,
 325          * we could probably use kobject_name(kobj); */
 326
 327         error = sysfs_rename_dir(kobj, new_name);
 328
 329         /* This function is mostly/only used for network interface.
 330          * Some hotplug package track interfaces by their name and
 331          * therefore want to know when the name is changed by the user. */
 332         if (!error)
 333                 kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 334
 335 out:
 336         kfree(devpath_string);
 337         kfree(devpath);
 338         kobject_put(kobj);
 339
 340         return error;
 341 }
 342
 343 /**
 344  *      kobject_move - move object to another parent
 345  *      @kobj:  object in question.
 346  *      @new_parent: object's new parent (can be NULL)
 347  */
 348
 349 int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 350 {
 351         int error;
 352         struct kobject *old_parent;
 353         const char *devpath = NULL;
 354         char *devpath_string = NULL;
 355         char *envp[2];
 356
 357         kobj = kobject_get(kobj);
 358         if (!kobj)
 359                 return -EINVAL;
 360         new_parent = kobject_get(new_parent);
 361         if (!new_parent) {
 362                 if (kobj->kset)
 363                         new_parent = kobject_get(&kobj->kset->kobj);
 364         }
 365         /* old object path */
 366         devpath = kobject_get_path(kobj, GFP_KERNEL);
 367         if (!devpath) {
 368                 error = -ENOMEM;
 369                 goto out;
 370         }
 371         devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
 372         if (!devpath_string) {
 373                 error = -ENOMEM;
 374                 goto out;
 375         }
 376         sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
 377         envp[0] = devpath_string;
 378         envp[1] = NULL;
 379         error = sysfs_move_dir(kobj, new_parent);
 380         if (error)
 381                 goto out;
 382         old_parent = kobj->parent;
 383         kobj->parent = new_parent;
 384         new_parent = NULL;
 385         kobject_put(old_parent);
 386         kobject_uevent_env(kobj, KOBJ_MOVE, envp);
 387 out:
 388         kobject_put(new_parent);
 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         const char *name = kobj->k_name;
 446
 447         pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
 448         if (t && t->release) {
 449                 t->release(kobj);
 450                 /* If we have a release function, we can guess that this was
 451                  * not a statically allocated kobject, so we should be safe to
 452                  * free the name */
 453                 kfree(name);
 454         }
 455         if (s)
 456                 kset_put(s);
 457         kobject_put(parent);
 458 }
 459
 460 static void kobject_release(struct kref *kref)
 461 {
 462         kobject_cleanup(container_of(kref, struct kobject, kref));
 463 }
 464
 465 /**
 466  *      kobject_put - decrement refcount for object.
 467  *      @kobj:  object.
 468  *
 469  *      Decrement the refcount, and if 0, call kobject_cleanup().
 470  */
 471 void kobject_put(struct kobject * kobj)
 472 {
 473         if (kobj)
 474                 kref_put(&kobj->kref, kobject_release);
 475 }
 476
 477
 478 static void dir_release(struct kobject *kobj)
 479 {
 480         kfree(kobj);
 481 }
 482
 483 static struct kobj_type dir_ktype = {
 484         .release        = dir_release,
 485         .sysfs_ops      = NULL,
 486         .default_attrs  = NULL,
 487 };
 488
 489 /**
 490  *      kobject_kset_add_dir - add sub directory of object.
 491  *      @kset:          kset the directory is belongs to.
 492  *      @parent:        object in which a directory is created.
 493  *      @name:  directory name.
 494  *
 495  *      Add a plain directory object as child of given object.
 496  */
 497 struct kobject *kobject_kset_add_dir(struct kset *kset,
 498                                      struct kobject *parent, const char *name)
 499 {
 500         struct kobject *k;
 501         int ret;
 502
 503         if (!parent)
 504                 return NULL;
 505
 506         k = kzalloc(sizeof(*k), GFP_KERNEL);
 507         if (!k)
 508                 return NULL;
 509
 510         k->kset = kset;
 511         k->parent = parent;
 512         k->ktype = &dir_ktype;
 513         kobject_set_name(k, name);
 514         ret = kobject_register(k);
 515         if (ret < 0) {
 516                 printk(KERN_WARNING "%s: kobject_register error: %d\n",
 517                         __func__, ret);
 518                 kobject_del(k);
 519                 return NULL;
 520         }
 521
 522         return k;
 523 }
 524
 525 /**
 526  *      kobject_add_dir - add sub directory of object.
 527  *      @parent:        object in which a directory is created.
 528  *      @name:  directory name.
 529  *
 530  *      Add a plain directory object as child of given object.
 531  */
 532 struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
 533 {
 534         return kobject_kset_add_dir(NULL, parent, name);
 535 }
 536
 537 /**
 538  *      kset_init - initialize a kset for use
 539  *      @k:     kset
 540  */
 541
 542 void kset_init(struct kset * k)
 543 {
 544         kobject_init(&k->kobj);
 545         INIT_LIST_HEAD(&k->list);
 546         spin_lock_init(&k->list_lock);
 547 }
 548
 549
 550 /**
 551  *      kset_add - add a kset object to the hierarchy.
 552  *      @k:     kset.
 553  */
 554
 555 int kset_add(struct kset * k)
 556 {
 557         return kobject_add(&k->kobj);
 558 }
 559
 560
 561 /**
 562  *      kset_register - initialize and add a kset.
 563  *      @k:     kset.
 564  */
 565
 566 int kset_register(struct kset * k)
 567 {
 568         int err;
 569
 570         if (!k)
 571                 return -EINVAL;
 572
 573         kset_init(k);
 574         err = kset_add(k);
 575         if (err)
 576                 return err;
 577         kobject_uevent(&k->kobj, KOBJ_ADD);
 578         return 0;
 579 }
 580
 581
 582 /**
 583  *      kset_unregister - remove a kset.
 584  *      @k:     kset.
 585  */
 586
 587 void kset_unregister(struct kset * k)
 588 {
 589         if (!k)
 590                 return;
 591         kobject_unregister(&k->kobj);
 592 }
 593
 594
 595 /**
 596  *      kset_find_obj - search for object in kset.
 597  *      @kset:  kset we're looking in.
 598  *      @name:  object's name.
 599  *
 600  *      Lock kset via @kset->subsys, and iterate over @kset->list,
 601  *      looking for a matching kobject. If matching object is found
 602  *      take a reference and return the object.
 603  */
 604
 605 struct kobject * kset_find_obj(struct kset * kset, const char * name)
 606 {
 607         struct list_head * entry;
 608         struct kobject * ret = NULL;
 609
 610         spin_lock(&kset->list_lock);
 611         list_for_each(entry,&kset->list) {
 612                 struct kobject * k = to_kobj(entry);
 613                 if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
 614                         ret = kobject_get(k);
 615                         break;
 616                 }
 617         }
 618         spin_unlock(&kset->list_lock);
 619         return ret;
 620 }
 621
 622 int subsystem_register(struct kset *s)
 623 {
 624         return kset_register(s);
 625 }
 626
 627 void subsystem_unregister(struct kset *s)
 628 {
 629         kset_unregister(s);
 630 }
 631
 632 /**
 633  *      subsystem_create_file - export sysfs attribute file.
 634  *      @s:     subsystem.
 635  *      @a:     subsystem attribute descriptor.
 636  */
 637
 638 int subsys_create_file(struct kset *s, struct subsys_attribute *a)
 639 {
 640         int error = 0;
 641
 642         if (!s || !a)
 643                 return -EINVAL;
 644
 645         if (kset_get(s)) {
 646                 error = sysfs_create_file(&s->kobj, &a->attr);
 647                 kset_put(s);
 648         }
 649         return error;
 650 }
 651
 652 EXPORT_SYMBOL(kobject_init);
 653 EXPORT_SYMBOL(kobject_register);
 654 EXPORT_SYMBOL(kobject_unregister);
 655 EXPORT_SYMBOL(kobject_get);
 656 EXPORT_SYMBOL(kobject_put);
 657 EXPORT_SYMBOL(kobject_add);
 658 EXPORT_SYMBOL(kobject_del);
 659
 660 EXPORT_SYMBOL(kset_register);
 661 EXPORT_SYMBOL(kset_unregister);
 662
 663 EXPORT_SYMBOL(subsystem_register);
 664 EXPORT_SYMBOL(subsystem_unregister);
 665 EXPORT_SYMBOL(subsys_create_file);