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