git.oblomov.eu Git - linux-2.6/blob - drivers/acpi/namespace/nsaccess.c

   1 /*******************************************************************************
   2  *
   3  * Module Name: nsaccess - Top-level functions for accessing ACPI namespace
   4  *
   5  ******************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2005, R. Byron Moore
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions, and the following disclaimer,
  16  *    without modification.
  17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  18  *    substantially similar to the "NO WARRANTY" disclaimer below
  19  *    ("Disclaimer") and any redistribution must be conditioned upon
  20  *    including a substantially similar Disclaimer requirement for further
  21  *    binary redistribution.
  22  * 3. Neither the names of the above-listed copyright holders nor the names
  23  *    of any contributors may be used to endorse or promote products derived
  24  *    from this software without specific prior written permission.
  25  *
  26  * Alternatively, this software may be distributed under the terms of the
  27  * GNU General Public License ("GPL") version 2 as published by the Free
  28  * Software Foundation.
  29  *
  30  * NO WARRANTY
  31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  41  * POSSIBILITY OF SUCH DAMAGES.
  42  */
  43
  44 #include <acpi/acpi.h>
  45 #include <acpi/amlcode.h>
  46 #include <acpi/acnamesp.h>
  47 #include <acpi/acdispat.h>
  48
  49 #define _COMPONENT          ACPI_NAMESPACE
  50 ACPI_MODULE_NAME("nsaccess")
  51
  52 /*******************************************************************************
  53  *
  54  * FUNCTION:    acpi_ns_root_initialize
  55  *
  56  * PARAMETERS:  None
  57  *
  58  * RETURN:      Status
  59  *
  60  * DESCRIPTION: Allocate and initialize the default root named objects
  61  *
  62  * MUTEX:       Locks namespace for entire execution
  63  *
  64  ******************************************************************************/
  65 acpi_status acpi_ns_root_initialize(void)
  66 {
  67         acpi_status status;
  68         const struct acpi_predefined_names *init_val = NULL;
  69         struct acpi_namespace_node *new_node;
  70         union acpi_operand_object *obj_desc;
  71         acpi_string val = NULL;
  72
  73         ACPI_FUNCTION_TRACE("ns_root_initialize");
  74
  75         status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
  76         if (ACPI_FAILURE(status)) {
  77                 return_ACPI_STATUS(status);
  78         }
  79
  80         /*
  81          * The global root ptr is initially NULL, so a non-NULL value indicates
  82          * that acpi_ns_root_initialize() has already been called; just return.
  83          */
  84         if (acpi_gbl_root_node) {
  85                 status = AE_OK;
  86                 goto unlock_and_exit;
  87         }
  88
  89         /*
  90          * Tell the rest of the subsystem that the root is initialized
  91          * (This is OK because the namespace is locked)
  92          */
  93         acpi_gbl_root_node = &acpi_gbl_root_node_struct;
  94
  95         /* Enter the pre-defined names in the name table */
  96
  97         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
  98                           "Entering predefined entries into namespace\n"));
  99
 100         for (init_val = acpi_gbl_pre_defined_names; init_val->name; init_val++) {
 101                 /* _OSI is optional for now, will be permanent later */
 102
 103                 if (!ACPI_STRCMP(init_val->name, "_OSI")
 104                     && !acpi_gbl_create_osi_method) {
 105                         continue;
 106                 }
 107
 108                 status = acpi_ns_lookup(NULL, init_val->name, init_val->type,
 109                                         ACPI_IMODE_LOAD_PASS2,
 110                                         ACPI_NS_NO_UPSEARCH, NULL, &new_node);
 111
 112                 if (ACPI_FAILURE(status) || (!new_node)) {      /* Must be on same line for code converter */
 113                         ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
 114                                           "Could not create predefined name %s, %s\n",
 115                                           init_val->name,
 116                                           acpi_format_exception(status)));
 117                 }
 118
 119                 /*
 120                  * Name entered successfully.
 121                  * If entry in pre_defined_names[] specifies an
 122                  * initial value, create the initial value.
 123                  */
 124                 if (init_val->val) {
 125                         status = acpi_os_predefined_override(init_val, &val);
 126                         if (ACPI_FAILURE(status)) {
 127                                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
 128                                                   "Could not override predefined %s\n",
 129                                                   init_val->name));
 130                         }
 131
 132                         if (!val) {
 133                                 val = init_val->val;
 134                         }
 135
 136                         /*
 137                          * Entry requests an initial value, allocate a
 138                          * descriptor for it.
 139                          */
 140                         obj_desc =
 141                             acpi_ut_create_internal_object(init_val->type);
 142                         if (!obj_desc) {
 143                                 status = AE_NO_MEMORY;
 144                                 goto unlock_and_exit;
 145                         }
 146
 147                         /*
 148                          * Convert value string from table entry to
 149                          * internal representation. Only types actually
 150                          * used for initial values are implemented here.
 151                          */
 152                         switch (init_val->type) {
 153                         case ACPI_TYPE_METHOD:
 154                                 obj_desc->method.param_count =
 155                                     (u8) ACPI_TO_INTEGER(val);
 156                                 obj_desc->common.flags |= AOPOBJ_DATA_VALID;
 157
 158 #if defined (ACPI_ASL_COMPILER)
 159
 160                                 /* save the parameter count for the i_aSL compiler */
 161
 162                                 new_node->value = obj_desc->method.param_count;
 163 #else
 164                                 /* Mark this as a very SPECIAL method */
 165
 166                                 obj_desc->method.method_flags =
 167                                     AML_METHOD_INTERNAL_ONLY;
 168
 169 #ifndef ACPI_DUMP_APP
 170                                 obj_desc->method.implementation =
 171                                     acpi_ut_osi_implementation;
 172 #endif
 173 #endif
 174                                 break;
 175
 176                         case ACPI_TYPE_INTEGER:
 177
 178                                 obj_desc->integer.value = ACPI_TO_INTEGER(val);
 179                                 break;
 180
 181                         case ACPI_TYPE_STRING:
 182
 183                                 /*
 184                                  * Build an object around the static string
 185                                  */
 186                                 obj_desc->string.length =
 187                                     (u32) ACPI_STRLEN(val);
 188                                 obj_desc->string.pointer = val;
 189                                 obj_desc->common.flags |= AOPOBJ_STATIC_POINTER;
 190                                 break;
 191
 192                         case ACPI_TYPE_MUTEX:
 193
 194                                 obj_desc->mutex.node = new_node;
 195                                 obj_desc->mutex.sync_level =
 196                                     (u8) (ACPI_TO_INTEGER(val) - 1);
 197
 198                                 if (ACPI_STRCMP(init_val->name, "_GL_") == 0) {
 199                                         /*
 200                                          * Create a counting semaphore for the
 201                                          * global lock
 202                                          */
 203                                         status =
 204                                             acpi_os_create_semaphore
 205                                             (ACPI_NO_UNIT_LIMIT, 1,
 206                                              &obj_desc->mutex.semaphore);
 207                                         if (ACPI_FAILURE(status)) {
 208                                                 acpi_ut_remove_reference
 209                                                     (obj_desc);
 210                                                 goto unlock_and_exit;
 211                                         }
 212
 213                                         /*
 214                                          * We just created the mutex for the
 215                                          * global lock, save it
 216                                          */
 217                                         acpi_gbl_global_lock_semaphore =
 218                                             obj_desc->mutex.semaphore;
 219                                 } else {
 220                                         /* Create a mutex */
 221
 222                                         status = acpi_os_create_semaphore(1, 1,
 223                                                                           &obj_desc->
 224                                                                           mutex.
 225                                                                           semaphore);
 226                                         if (ACPI_FAILURE(status)) {
 227                                                 acpi_ut_remove_reference
 228                                                     (obj_desc);
 229                                                 goto unlock_and_exit;
 230                                         }
 231                                 }
 232                                 break;
 233
 234                         default:
 235
 236                                 ACPI_REPORT_ERROR(("Unsupported initial type value %X\n", init_val->type));
 237                                 acpi_ut_remove_reference(obj_desc);
 238                                 obj_desc = NULL;
 239                                 continue;
 240                         }
 241
 242                         /* Store pointer to value descriptor in the Node */
 243
 244                         status = acpi_ns_attach_object(new_node, obj_desc,
 245                                                        ACPI_GET_OBJECT_TYPE
 246                                                        (obj_desc));
 247
 248                         /* Remove local reference to the object */
 249
 250                         acpi_ut_remove_reference(obj_desc);
 251                 }
 252         }
 253
 254       unlock_and_exit:
 255         (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
 256
 257         /* Save a handle to "_GPE", it is always present */
 258
 259         if (ACPI_SUCCESS(status)) {
 260                 status =
 261                     acpi_ns_get_node_by_path("\\_GPE", NULL,
 262                                              ACPI_NS_NO_UPSEARCH,
 263                                              &acpi_gbl_fadt_gpe_device);
 264         }
 265
 266         return_ACPI_STATUS(status);
 267 }
 268
 269 /*******************************************************************************
 270  *
 271  * FUNCTION:    acpi_ns_lookup
 272  *
 273  * PARAMETERS:  scope_info      - Current scope info block
 274  *              Pathname        - Search pathname, in internal format
 275  *                                (as represented in the AML stream)
 276  *              Type            - Type associated with name
 277  *              interpreter_mode - IMODE_LOAD_PASS2 => add name if not found
 278  *              Flags           - Flags describing the search restrictions
 279  *              walk_state      - Current state of the walk
 280  *              return_node     - Where the Node is placed (if found
 281  *                                or created successfully)
 282  *
 283  * RETURN:      Status
 284  *
 285  * DESCRIPTION: Find or enter the passed name in the name space.
 286  *              Log an error if name not found in Exec mode.
 287  *
 288  * MUTEX:       Assumes namespace is locked.
 289  *
 290  ******************************************************************************/
 291
 292 acpi_status
 293 acpi_ns_lookup(union acpi_generic_state *scope_info,
 294                char *pathname,
 295                acpi_object_type type,
 296                acpi_interpreter_mode interpreter_mode,
 297                u32 flags,
 298                struct acpi_walk_state *walk_state,
 299                struct acpi_namespace_node **return_node)
 300 {
 301         acpi_status status;
 302         char *path = pathname;
 303         struct acpi_namespace_node *prefix_node;
 304         struct acpi_namespace_node *current_node = NULL;
 305         struct acpi_namespace_node *this_node = NULL;
 306         u32 num_segments;
 307         u32 num_carats;
 308         acpi_name simple_name;
 309         acpi_object_type type_to_check_for;
 310         acpi_object_type this_search_type;
 311         u32 search_parent_flag = ACPI_NS_SEARCH_PARENT;
 312         u32 local_flags = flags & ~(ACPI_NS_ERROR_IF_FOUND |
 313                                     ACPI_NS_SEARCH_PARENT);
 314
 315         ACPI_FUNCTION_TRACE("ns_lookup");
 316
 317         if (!return_node) {
 318                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 319         }
 320
 321         acpi_gbl_ns_lookup_count++;
 322         *return_node = ACPI_ENTRY_NOT_FOUND;
 323
 324         if (!acpi_gbl_root_node) {
 325                 return_ACPI_STATUS(AE_NO_NAMESPACE);
 326         }
 327
 328         /*
 329          * Get the prefix scope.
 330          * A null scope means use the root scope
 331          */
 332         if ((!scope_info) || (!scope_info->scope.node)) {
 333                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 334                                   "Null scope prefix, using root node (%p)\n",
 335                                   acpi_gbl_root_node));
 336
 337                 prefix_node = acpi_gbl_root_node;
 338         } else {
 339                 prefix_node = scope_info->scope.node;
 340                 if (ACPI_GET_DESCRIPTOR_TYPE(prefix_node) !=
 341                     ACPI_DESC_TYPE_NAMED) {
 342                         ACPI_REPORT_ERROR(("ns_lookup: %p is not a namespace node [%s]\n", prefix_node, acpi_ut_get_descriptor_name(prefix_node)));
 343                         return_ACPI_STATUS(AE_AML_INTERNAL);
 344                 }
 345
 346                 /*
 347                  * This node might not be a actual "scope" node (such as a
 348                  * Device/Method, etc.)  It could be a Package or other object node.
 349                  * Backup up the tree to find the containing scope node.
 350                  */
 351                 while (!acpi_ns_opens_scope(prefix_node->type) &&
 352                        prefix_node->type != ACPI_TYPE_ANY) {
 353                         prefix_node = acpi_ns_get_parent_node(prefix_node);
 354                 }
 355         }
 356
 357         /* Save type   TBD: may be no longer necessary */
 358
 359         type_to_check_for = type;
 360
 361         /*
 362          * Begin examination of the actual pathname
 363          */
 364         if (!pathname) {
 365                 /* A Null name_path is allowed and refers to the root */
 366
 367                 num_segments = 0;
 368                 this_node = acpi_gbl_root_node;
 369                 path = "";
 370
 371                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 372                                   "Null Pathname (Zero segments), Flags=%X\n",
 373                                   flags));
 374         } else {
 375                 /*
 376                  * Name pointer is valid (and must be in internal name format)
 377                  *
 378                  * Check for scope prefixes:
 379                  *
 380                  * As represented in the AML stream, a namepath consists of an
 381                  * optional scope prefix followed by a name segment part.
 382                  *
 383                  * If present, the scope prefix is either a Root Prefix (in
 384                  * which case the name is fully qualified), or one or more
 385                  * Parent Prefixes (in which case the name's scope is relative
 386                  * to the current scope).
 387                  */
 388                 if (*path == (u8) AML_ROOT_PREFIX) {
 389                         /* Pathname is fully qualified, start from the root */
 390
 391                         this_node = acpi_gbl_root_node;
 392                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 393
 394                         /* Point to name segment part */
 395
 396                         path++;
 397
 398                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 399                                           "Path is absolute from root [%p]\n",
 400                                           this_node));
 401                 } else {
 402                         /* Pathname is relative to current scope, start there */
 403
 404                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 405                                           "Searching relative to prefix scope [%4.4s] (%p)\n",
 406                                           acpi_ut_get_node_name(prefix_node),
 407                                           prefix_node));
 408
 409                         /*
 410                          * Handle multiple Parent Prefixes (carat) by just getting
 411                          * the parent node for each prefix instance.
 412                          */
 413                         this_node = prefix_node;
 414                         num_carats = 0;
 415                         while (*path == (u8) AML_PARENT_PREFIX) {
 416                                 /* Name is fully qualified, no search rules apply */
 417
 418                                 search_parent_flag = ACPI_NS_NO_UPSEARCH;
 419                                 /*
 420                                  * Point past this prefix to the name segment
 421                                  * part or the next Parent Prefix
 422                                  */
 423                                 path++;
 424
 425                                 /* Backup to the parent node */
 426
 427                                 num_carats++;
 428                                 this_node = acpi_ns_get_parent_node(this_node);
 429                                 if (!this_node) {
 430                                         /* Current scope has no parent scope */
 431
 432                                         ACPI_REPORT_ERROR(("ACPI path has too many parent prefixes (^) - reached beyond root node\n"));
 433                                         return_ACPI_STATUS(AE_NOT_FOUND);
 434                                 }
 435                         }
 436
 437                         if (search_parent_flag == ACPI_NS_NO_UPSEARCH) {
 438                                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 439                                                   "Search scope is [%4.4s], path has %d carat(s)\n",
 440                                                   acpi_ut_get_node_name
 441                                                   (this_node), num_carats));
 442                         }
 443                 }
 444
 445                 /*
 446                  * Determine the number of ACPI name segments in this pathname.
 447                  *
 448                  * The segment part consists of either:
 449                  *  - A Null name segment (0)
 450                  *  - A dual_name_prefix followed by two 4-byte name segments
 451                  *  - A multi_name_prefix followed by a byte indicating the
 452                  *      number of segments and the segments themselves.
 453                  *  - A single 4-byte name segment
 454                  *
 455                  * Examine the name prefix opcode, if any, to determine the number of
 456                  * segments.
 457                  */
 458                 switch (*path) {
 459                 case 0:
 460                         /*
 461                          * Null name after a root or parent prefixes. We already
 462                          * have the correct target node and there are no name segments.
 463                          */
 464                         num_segments = 0;
 465                         type = this_node->type;
 466
 467                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 468                                           "Prefix-only Pathname (Zero name segments), Flags=%X\n",
 469                                           flags));
 470                         break;
 471
 472                 case AML_DUAL_NAME_PREFIX:
 473
 474                         /* More than one name_seg, search rules do not apply */
 475
 476                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 477
 478                         /* Two segments, point to first name segment */
 479
 480                         num_segments = 2;
 481                         path++;
 482
 483                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 484                                           "Dual Pathname (2 segments, Flags=%X)\n",
 485                                           flags));
 486                         break;
 487
 488                 case AML_MULTI_NAME_PREFIX_OP:
 489
 490                         /* More than one name_seg, search rules do not apply */
 491
 492                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 493
 494                         /* Extract segment count, point to first name segment */
 495
 496                         path++;
 497                         num_segments = (u32) (u8) * path;
 498                         path++;
 499
 500                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 501                                           "Multi Pathname (%d Segments, Flags=%X) \n",
 502                                           num_segments, flags));
 503                         break;
 504
 505                 default:
 506                         /*
 507                          * Not a Null name, no Dual or Multi prefix, hence there is
 508                          * only one name segment and Pathname is already pointing to it.
 509                          */
 510                         num_segments = 1;
 511
 512                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 513                                           "Simple Pathname (1 segment, Flags=%X)\n",
 514                                           flags));
 515                         break;
 516                 }
 517
 518                 ACPI_DEBUG_EXEC(acpi_ns_print_pathname(num_segments, path));
 519         }
 520
 521         /*
 522          * Search namespace for each segment of the name.  Loop through and
 523          * verify (or add to the namespace) each name segment.
 524          *
 525          * The object type is significant only at the last name
 526          * segment.  (We don't care about the types along the path, only
 527          * the type of the final target object.)
 528          */
 529         this_search_type = ACPI_TYPE_ANY;
 530         current_node = this_node;
 531         while (num_segments && current_node) {
 532                 num_segments--;
 533                 if (!num_segments) {
 534                         /*
 535                          * This is the last segment, enable typechecking
 536                          */
 537                         this_search_type = type;
 538
 539                         /*
 540                          * Only allow automatic parent search (search rules) if the caller
 541                          * requested it AND we have a single, non-fully-qualified name_seg
 542                          */
 543                         if ((search_parent_flag != ACPI_NS_NO_UPSEARCH) &&
 544                             (flags & ACPI_NS_SEARCH_PARENT)) {
 545                                 local_flags |= ACPI_NS_SEARCH_PARENT;
 546                         }
 547
 548                         /* Set error flag according to caller */
 549
 550                         if (flags & ACPI_NS_ERROR_IF_FOUND) {
 551                                 local_flags |= ACPI_NS_ERROR_IF_FOUND;
 552                         }
 553                 }
 554
 555                 /* Extract one ACPI name from the front of the pathname */
 556
 557                 ACPI_MOVE_32_TO_32(&simple_name, path);
 558
 559                 /* Try to find the single (4 character) ACPI name */
 560
 561                 status =
 562                     acpi_ns_search_and_enter(simple_name, walk_state,
 563                                              current_node, interpreter_mode,
 564                                              this_search_type, local_flags,
 565                                              &this_node);
 566                 if (ACPI_FAILURE(status)) {
 567                         if (status == AE_NOT_FOUND) {
 568                                 /* Name not found in ACPI namespace */
 569
 570                                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 571                                                   "Name [%4.4s] not found in scope [%4.4s] %p\n",
 572                                                   (char *)&simple_name,
 573                                                   (char *)&current_node->name,
 574                                                   current_node));
 575                         }
 576
 577                         *return_node = this_node;
 578                         return_ACPI_STATUS(status);
 579                 }
 580
 581                 /*
 582                  * Sanity typecheck of the target object:
 583                  *
 584                  * If 1) This is the last segment (num_segments == 0)
 585                  *    2) And we are looking for a specific type
 586                  *       (Not checking for TYPE_ANY)
 587                  *    3) Which is not an alias
 588                  *    4) Which is not a local type (TYPE_SCOPE)
 589                  *    5) And the type of target object is known (not TYPE_ANY)
 590                  *    6) And target object does not match what we are looking for
 591                  *
 592                  * Then we have a type mismatch.  Just warn and ignore it.
 593                  */
 594                 if ((num_segments == 0) &&
 595                     (type_to_check_for != ACPI_TYPE_ANY) &&
 596                     (type_to_check_for != ACPI_TYPE_LOCAL_ALIAS) &&
 597                     (type_to_check_for != ACPI_TYPE_LOCAL_METHOD_ALIAS) &&
 598                     (type_to_check_for != ACPI_TYPE_LOCAL_SCOPE) &&
 599                     (this_node->type != ACPI_TYPE_ANY) &&
 600                     (this_node->type != type_to_check_for)) {
 601                         /* Complain about a type mismatch */
 602
 603                         ACPI_REPORT_WARNING(("ns_lookup: Type mismatch on %4.4s (%s), searching for (%s)\n", (char *)&simple_name, acpi_ut_get_type_name(this_node->type), acpi_ut_get_type_name(type_to_check_for)));
 604                 }
 605
 606                 /*
 607                  * If this is the last name segment and we are not looking for a
 608                  * specific type, but the type of found object is known, use that type
 609                  * to see if it opens a scope.
 610                  */
 611                 if ((num_segments == 0) && (type == ACPI_TYPE_ANY)) {
 612                         type = this_node->type;
 613                 }
 614
 615                 /* Point to next name segment and make this node current */
 616
 617                 path += ACPI_NAME_SIZE;
 618                 current_node = this_node;
 619         }
 620
 621         /*
 622          * Always check if we need to open a new scope
 623          */
 624         if (!(flags & ACPI_NS_DONT_OPEN_SCOPE) && (walk_state)) {
 625                 /*
 626                  * If entry is a type which opens a scope, push the new scope on the
 627                  * scope stack.
 628                  */
 629                 if (acpi_ns_opens_scope(type)) {
 630                         status =
 631                             acpi_ds_scope_stack_push(this_node, type,
 632                                                      walk_state);
 633                         if (ACPI_FAILURE(status)) {
 634                                 return_ACPI_STATUS(status);
 635                         }
 636                 }
 637         }
 638
 639         *return_node = this_node;
 640         return_ACPI_STATUS(AE_OK);
 641 }