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 #undef DEBUG
  14
  15 #include <linux/kobject.h>
  16 #include <linux/string.h>
  17 #include <linux/module.h>
  18 #include <linux/stat.h>
  19
  20 /**
  21  *      populate_dir - populate directory with attributes.
  22  *      @kobj:  object we're working on.
  23  *
  24  *      Most subsystems have a set of default attributes that
  25  *      are associated with an object that registers with them.
  26  *      This is a helper called during object registration that
  27  *      loops through the default attributes of the subsystem
  28  *      and creates attributes files for them in sysfs.
  29  *
  30  */
  31
  32 static int populate_dir(struct kobject * kobj)
  33 {
  34         struct kobj_type * t = get_ktype(kobj);
  35         struct attribute * attr;
  36         int error = 0;
  37         int i;
  38
  39         if (t && t->default_attrs) {
  40                 for (i = 0; (attr = t->default_attrs[i]); i++) {
  41                         if ((error = sysfs_create_file(kobj,attr)))
  42                                 break;
  43                 }
  44         }
  45         return error;
  46 }
  47
  48 static int create_dir(struct kobject * kobj)
  49 {
  50         int error = 0;
  51         if (kobject_name(kobj)) {
  52                 error = sysfs_create_dir(kobj);
  53                 if (!error) {
  54                         if ((error = populate_dir(kobj)))
  55                                 sysfs_remove_dir(kobj);
  56                 }
  57         }
  58         return error;
  59 }
  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
  68 #ifdef CONFIG_HOTPLUG
  69 static int get_kobj_path_length(struct kset *kset, struct kobject *kobj)
  70 {
  71         int length = 1;
  72         struct kobject * parent = kobj;
  73
  74         /* walk up the ancestors until we hit the one pointing to the
  75          * root.
  76          * Add 1 to strlen for leading '/' of each level.
  77          */
  78         do {
  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 kset *kset, 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 #define BUFFER_SIZE     1024    /* should be enough memory for the env */
 102 #define NUM_ENVP        32      /* number of env pointers */
 103 static unsigned long sequence_num;
 104 static spinlock_t sequence_lock = SPIN_LOCK_UNLOCKED;
 105
 106 static void kset_hotplug(const char *action, struct kset *kset,
 107                          struct kobject *kobj)
 108 {
 109         char *argv [3];
 110         char **envp = NULL;
 111         char *buffer = NULL;
 112         char *scratch;
 113         int i = 0;
 114         int retval;
 115         int kobj_path_length;
 116         char *kobj_path = NULL;
 117         char *name = NULL;
 118         unsigned long seq;
 119
 120         /* If the kset has a filter operation, call it. If it returns
 121            failure, no hotplug event is required. */
 122         if (kset->hotplug_ops->filter) {
 123                 if (!kset->hotplug_ops->filter(kset, kobj))
 124                         return;
 125         }
 126
 127         pr_debug ("%s\n", __FUNCTION__);
 128
 129         if (!hotplug_path[0])
 130                 return;
 131
 132         envp = kmalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
 133         if (!envp)
 134                 return;
 135         memset (envp, 0x00, NUM_ENVP * sizeof (char *));
 136
 137         buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
 138         if (!buffer)
 139                 goto exit;
 140
 141         if (kset->hotplug_ops->name)
 142                 name = kset->hotplug_ops->name(kset, kobj);
 143         if (name == NULL)
 144                 name = kset->kobj.name;
 145
 146         argv [0] = hotplug_path;
 147         argv [1] = name;
 148         argv [2] = 0;
 149
 150         /* minimal command environment */
 151         envp [i++] = "HOME=/";
 152         envp [i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 153
 154         scratch = buffer;
 155
 156         envp [i++] = scratch;
 157         scratch += sprintf(scratch, "ACTION=%s", action) + 1;
 158
 159         spin_lock(&sequence_lock);
 160         seq = sequence_num++;
 161         spin_unlock(&sequence_lock);
 162
 163         envp [i++] = scratch;
 164         scratch += sprintf(scratch, "SEQNUM=%ld", seq) + 1;
 165
 166         kobj_path_length = get_kobj_path_length (kset, kobj);
 167         kobj_path = kmalloc (kobj_path_length, GFP_KERNEL);
 168         if (!kobj_path)
 169                 goto exit;
 170         memset (kobj_path, 0x00, kobj_path_length);
 171         fill_kobj_path (kset, kobj, kobj_path, kobj_path_length);
 172
 173         envp [i++] = scratch;
 174         scratch += sprintf (scratch, "DEVPATH=%s", kobj_path) + 1;
 175
 176         if (kset->hotplug_ops->hotplug) {
 177                 /* have the kset specific function add its stuff */
 178                 retval = kset->hotplug_ops->hotplug (kset, kobj,
 179                                   &envp[i], NUM_ENVP - i, scratch,
 180                                   BUFFER_SIZE - (scratch - buffer));
 181                 if (retval) {
 182                         pr_debug ("%s - hotplug() returned %d\n",
 183                                   __FUNCTION__, retval);
 184                         goto exit;
 185                 }
 186         }
 187
 188         pr_debug ("%s: %s %s %s %s %s %s %s\n", __FUNCTION__, argv[0], argv[1],
 189                   envp[0], envp[1], envp[2], envp[3], envp[4]);
 190         retval = call_usermodehelper (argv[0], argv, envp, 0);
 191         if (retval)
 192                 pr_debug ("%s - call_usermodehelper returned %d\n",
 193                           __FUNCTION__, retval);
 194
 195 exit:
 196         kfree(kobj_path);
 197         kfree(buffer);
 198         kfree(envp);
 199         return;
 200 }
 201
 202 void kobject_hotplug(const char *action, struct kobject *kobj)
 203 {
 204         struct kobject * top_kobj = kobj;
 205
 206         /* If this kobj does not belong to a kset,
 207            try to find a parent that does. */
 208         if (!top_kobj->kset && top_kobj->parent) {
 209                 do {
 210                         top_kobj = top_kobj->parent;
 211                 } while (!top_kobj->kset && top_kobj->parent);
 212         }
 213
 214         if (top_kobj->kset && top_kobj->kset->hotplug_ops)
 215                 kset_hotplug(action, top_kobj->kset, kobj);
 216 }
 217 #else
 218 void kobject_hotplug(const char *action, struct kobject *kobj)
 219 {
 220         return;
 221 }
 222 #endif  /* CONFIG_HOTPLUG */
 223
 224 /**
 225  *      kobject_init - initialize object.
 226  *      @kobj:  object in question.
 227  */
 228
 229 void kobject_init(struct kobject * kobj)
 230 {
 231         atomic_set(&kobj->refcount,1);
 232         INIT_LIST_HEAD(&kobj->entry);
 233         kobj->kset = kset_get(kobj->kset);
 234 }
 235
 236
 237 /**
 238  *      unlink - remove kobject from kset list.
 239  *      @kobj:  kobject.
 240  *
 241  *      Remove the kobject from the kset list and decrement
 242  *      its parent's refcount.
 243  *      This is separated out, so we can use it in both
 244  *      kobject_del() and kobject_add() on error.
 245  */
 246
 247 static void unlink(struct kobject * kobj)
 248 {
 249         if (kobj->kset) {
 250                 down_write(&kobj->kset->subsys->rwsem);
 251                 list_del_init(&kobj->entry);
 252                 up_write(&kobj->kset->subsys->rwsem);
 253         }
 254         kobject_put(kobj);
 255 }
 256
 257 /**
 258  *      kobject_add - add an object to the hierarchy.
 259  *      @kobj:  object.
 260  */
 261
 262 int kobject_add(struct kobject * kobj)
 263 {
 264         int error = 0;
 265         struct kobject * parent;
 266
 267         if (!(kobj = kobject_get(kobj)))
 268                 return -ENOENT;
 269         if (!kobj->k_name)
 270                 kobj->k_name = kobj->name;
 271         parent = kobject_get(kobj->parent);
 272
 273         pr_debug("kobject %s: registering. parent: %s, set: %s\n",
 274                  kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>",
 275                  kobj->kset ? kobj->kset->kobj.name : "<NULL>" );
 276
 277         if (kobj->kset) {
 278                 down_write(&kobj->kset->subsys->rwsem);
 279
 280                 if (!parent)
 281                         parent = kobject_get(&kobj->kset->kobj);
 282
 283                 list_add_tail(&kobj->entry,&kobj->kset->list);
 284                 up_write(&kobj->kset->subsys->rwsem);
 285         }
 286         kobj->parent = parent;
 287
 288         error = create_dir(kobj);
 289         if (error) {
 290                 unlink(kobj);
 291                 if (parent)
 292                         kobject_put(parent);
 293         } else {
 294                 kobject_hotplug("add", kobj);
 295         }
 296
 297         return error;
 298 }
 299
 300
 301 /**
 302  *      kobject_register - initialize and add an object.
 303  *      @kobj:  object in question.
 304  */
 305
 306 int kobject_register(struct kobject * kobj)
 307 {
 308         int error = 0;
 309         if (kobj) {
 310                 kobject_init(kobj);
 311                 error = kobject_add(kobj);
 312                 if (error) {
 313                         printk("kobject_register failed for %s (%d)\n",
 314                                kobject_name(kobj),error);
 315                         dump_stack();
 316                 }
 317         } else
 318                 error = -EINVAL;
 319         return error;
 320 }
 321
 322
 323 /**
 324  *      kobject_set_name - Set the name of an object
 325  *      @kobj:  object.
 326  *      @name:  name.
 327  *
 328  *      If strlen(name) < KOBJ_NAME_LEN, then use a dynamically allocated
 329  *      string that @kobj->k_name points to. Otherwise, use the static
 330  *      @kobj->name array.
 331  */
 332
 333 int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
 334 {
 335         int error = 0;
 336         int limit = KOBJ_NAME_LEN;
 337         int need;
 338         va_list args;
 339         char * name;
 340
 341         va_start(args,fmt);
 342         /*
 343          * First, try the static array
 344          */
 345         need = vsnprintf(kobj->name,limit,fmt,args);
 346         if (need < limit)
 347                 name = kobj->name;
 348         else {
 349                 /*
 350                  * Need more space? Allocate it and try again
 351                  */
 352                 name = kmalloc(need,GFP_KERNEL);
 353                 if (!name) {
 354                         error = -ENOMEM;
 355                         goto Done;
 356                 }
 357                 limit = need;
 358                 need = vsnprintf(name,limit,fmt,args);
 359
 360                 /* Still? Give up. */
 361                 if (need > limit) {
 362                         kfree(name);
 363                         error = -EFAULT;
 364                         goto Done;
 365                 }
 366         }
 367
 368         /* Free the old name, if necessary. */
 369         if (kobj->k_name && kobj->k_name != kobj->name)
 370                 kfree(kobj->k_name);
 371
 372         /* Now, set the new name */
 373         kobj->k_name = name;
 374  Done:
 375         va_end(args);
 376         return error;
 377 }
 378
 379 EXPORT_SYMBOL(kobject_set_name);
 380
 381
 382 /**
 383  *      kobject_rename - change the name of an object
 384  *      @kobj:  object in question.
 385  *      @new_name: object's new name
 386  */
 387
 388 void kobject_rename(struct kobject * kobj, char *new_name)
 389 {
 390         kobj = kobject_get(kobj);
 391         if (!kobj)
 392                 return;
 393         sysfs_rename_dir(kobj, new_name);
 394         kobject_put(kobj);
 395 }
 396
 397 /**
 398  *      kobject_del - unlink kobject from hierarchy.
 399  *      @kobj:  object.
 400  */
 401
 402 void kobject_del(struct kobject * kobj)
 403 {
 404         kobject_hotplug("remove", kobj);
 405         sysfs_remove_dir(kobj);
 406         unlink(kobj);
 407 }
 408
 409 /**
 410  *      kobject_unregister - remove object from hierarchy and decrement refcount.
 411  *      @kobj:  object going away.
 412  */
 413
 414 void kobject_unregister(struct kobject * kobj)
 415 {
 416         pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
 417         kobject_del(kobj);
 418         kobject_put(kobj);
 419 }
 420
 421 /**
 422  *      kobject_get - increment refcount for object.
 423  *      @kobj:  object.
 424  */
 425
 426 struct kobject * kobject_get(struct kobject * kobj)
 427 {
 428         if (kobj) {
 429                 WARN_ON(!atomic_read(&kobj->refcount));
 430                 atomic_inc(&kobj->refcount);
 431         }
 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         if (parent)
 455                 kobject_put(parent);
 456 }
 457
 458 /**
 459  *      kobject_put - decrement refcount for object.
 460  *      @kobj:  object.
 461  *
 462  *      Decrement the refcount, and if 0, call kobject_cleanup().
 463  */
 464
 465 void kobject_put(struct kobject * kobj)
 466 {
 467         if (atomic_dec_and_test(&kobj->refcount))
 468                 kobject_cleanup(kobj);
 469 }
 470
 471
 472 /**
 473  *      kset_init - initialize a kset for use
 474  *      @k:     kset
 475  */
 476
 477 void kset_init(struct kset * k)
 478 {
 479         kobject_init(&k->kobj);
 480         INIT_LIST_HEAD(&k->list);
 481 }
 482
 483
 484 /**
 485  *      kset_add - add a kset object to the hierarchy.
 486  *      @k:     kset.
 487  *
 488  *      Simply, this adds the kset's embedded kobject to the
 489  *      hierarchy.
 490  *      We also try to make sure that the kset's embedded kobject
 491  *      has a parent before it is added. We only care if the embedded
 492  *      kobject is not part of a kset itself, since kobject_add()
 493  *      assigns a parent in that case.
 494  *      If that is the case, and the kset has a controlling subsystem,
 495  *      then we set the kset's parent to be said subsystem.
 496  */
 497
 498 int kset_add(struct kset * k)
 499 {
 500         if (!k->kobj.parent && !k->kobj.kset && k->subsys)
 501                 k->kobj.parent = &k->subsys->kset.kobj;
 502
 503         return kobject_add(&k->kobj);
 504 }
 505
 506
 507 /**
 508  *      kset_register - initialize and add a kset.
 509  *      @k:     kset.
 510  */
 511
 512 int kset_register(struct kset * k)
 513 {
 514         kset_init(k);
 515         return kset_add(k);
 516 }
 517
 518
 519 /**
 520  *      kset_unregister - remove a kset.
 521  *      @k:     kset.
 522  */
 523
 524 void kset_unregister(struct kset * k)
 525 {
 526         kobject_unregister(&k->kobj);
 527 }
 528
 529
 530 /**
 531  *      kset_find_obj - search for object in kset.
 532  *      @kset:  kset we're looking in.
 533  *      @name:  object's name.
 534  *
 535  *      Lock kset via @kset->subsys, and iterate over @kset->list,
 536  *      looking for a matching kobject. Return object if found.
 537  */
 538
 539 struct kobject * kset_find_obj(struct kset * kset, const char * name)
 540 {
 541         struct list_head * entry;
 542         struct kobject * ret = NULL;
 543
 544         down_read(&kset->subsys->rwsem);
 545         list_for_each(entry,&kset->list) {
 546                 struct kobject * k = to_kobj(entry);
 547                 if (kobject_name(k) && (!strcmp(kobject_name(k),name))) {
 548                         ret = k;
 549                         break;
 550                 }
 551         }
 552         up_read(&kset->subsys->rwsem);
 553         return ret;
 554 }
 555
 556
 557 void subsystem_init(struct subsystem * s)
 558 {
 559         init_rwsem(&s->rwsem);
 560         kset_init(&s->kset);
 561 }
 562
 563 /**
 564  *      subsystem_register - register a subsystem.
 565  *      @s:     the subsystem we're registering.
 566  *
 567  *      Once we register the subsystem, we want to make sure that
 568  *      the kset points back to this subsystem for correct usage of
 569  *      the rwsem.
 570  */
 571
 572 int subsystem_register(struct subsystem * s)
 573 {
 574         int error;
 575
 576         subsystem_init(s);
 577         pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
 578
 579         if (!(error = kset_add(&s->kset))) {
 580                 if (!s->kset.subsys)
 581                         s->kset.subsys = s;
 582         }
 583         return error;
 584 }
 585
 586 void subsystem_unregister(struct subsystem * s)
 587 {
 588         pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
 589         kset_unregister(&s->kset);
 590 }
 591
 592
 593 /**
 594  *      subsystem_create_file - export sysfs attribute file.
 595  *      @s:     subsystem.
 596  *      @a:     subsystem attribute descriptor.
 597  */
 598
 599 int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
 600 {
 601         int error = 0;
 602         if (subsys_get(s)) {
 603                 error = sysfs_create_file(&s->kset.kobj,&a->attr);
 604                 subsys_put(s);
 605         }
 606         return error;
 607 }
 608
 609
 610 /**
 611  *      subsystem_remove_file - remove sysfs attribute file.
 612  *      @s:     subsystem.
 613  *      @a:     attribute desciptor.
 614  */
 615
 616 void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
 617 {
 618         if (subsys_get(s)) {
 619                 sysfs_remove_file(&s->kset.kobj,&a->attr);
 620                 subsys_put(s);
 621         }
 622 }
 623
 624
 625 EXPORT_SYMBOL(kobject_init);
 626 EXPORT_SYMBOL(kobject_register);
 627 EXPORT_SYMBOL(kobject_unregister);
 628 EXPORT_SYMBOL(kobject_get);
 629 EXPORT_SYMBOL(kobject_put);
 630 EXPORT_SYMBOL(kobject_add);
 631 EXPORT_SYMBOL(kobject_del);
 632 EXPORT_SYMBOL(kobject_rename);
 633 EXPORT_SYMBOL(kobject_hotplug);
 634
 635 EXPORT_SYMBOL(kset_register);
 636 EXPORT_SYMBOL(kset_unregister);
 637 EXPORT_SYMBOL(kset_find_obj);
 638
 639 EXPORT_SYMBOL(subsystem_init);
 640 EXPORT_SYMBOL(subsystem_register);
 641 EXPORT_SYMBOL(subsystem_unregister);
 642 EXPORT_SYMBOL(subsys_create_file);
 643 EXPORT_SYMBOL(subsys_remove_file);