err.no 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
  45 #include <acpi/acpi.h>
  46 #include <acpi/amlcode.h>
  47 #include <acpi/acnamesp.h>
  48 #include <acpi/acdispat.h>
  49
  50
  51 #define _COMPONENT          ACPI_NAMESPACE
  52          ACPI_MODULE_NAME    ("nsaccess")
  53
  54
  55 /*******************************************************************************
  56  *
  57  * FUNCTION:    acpi_ns_root_initialize
  58  *
  59  * PARAMETERS:  None
  60  *
  61  * RETURN:      Status
  62  *
  63  * DESCRIPTION: Allocate and initialize the default root named objects
  64  *
  65  * MUTEX:       Locks namespace for entire execution
  66  *
  67  ******************************************************************************/
  68
  69 acpi_status
  70 acpi_ns_root_initialize (
  71         void)
  72 {
  73         acpi_status                         status;
  74         const struct acpi_predefined_names *init_val = NULL;
  75         struct acpi_namespace_node          *new_node;
  76         union acpi_operand_object           *obj_desc;
  77         acpi_string                         val = NULL;
  78
  79
  80         ACPI_FUNCTION_TRACE ("ns_root_initialize");
  81
  82
  83         status = acpi_ut_acquire_mutex (ACPI_MTX_NAMESPACE);
  84         if (ACPI_FAILURE (status)) {
  85                 return_ACPI_STATUS (status);
  86         }
  87
  88         /*
  89          * The global root ptr is initially NULL, so a non-NULL value indicates
  90          * that acpi_ns_root_initialize() has already been called; just return.
  91          */
  92         if (acpi_gbl_root_node) {
  93                 status = AE_OK;
  94                 goto unlock_and_exit;
  95         }
  96
  97         /*
  98          * Tell the rest of the subsystem that the root is initialized
  99          * (This is OK because the namespace is locked)
 100          */
 101         acpi_gbl_root_node = &acpi_gbl_root_node_struct;
 102
 103         /* Enter the pre-defined names in the name table */
 104
 105         ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
 106                 "Entering predefined entries into namespace\n"));
 107
 108         for (init_val = acpi_gbl_pre_defined_names; init_val->name; init_val++) {
 109                 /* _OSI is optional for now, will be permanent later */
 110
 111                 if (!ACPI_STRCMP (init_val->name, "_OSI") && !acpi_gbl_create_osi_method) {
 112                         continue;
 113                 }
 114
 115                 status = acpi_ns_lookup (NULL, init_val->name, init_val->type,
 116                                   ACPI_IMODE_LOAD_PASS2, ACPI_NS_NO_UPSEARCH,
 117                                   NULL, &new_node);
 118
 119                 if (ACPI_FAILURE (status) || (!new_node)) /* Must be on same line for code converter */ {
 120                         ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
 121                                 "Could not create predefined name %s, %s\n",
 122                                 init_val->name, acpi_format_exception (status)));
 123                 }
 124
 125                 /*
 126                  * Name entered successfully.
 127                  * If entry in pre_defined_names[] specifies an
 128                  * initial value, create the initial value.
 129                  */
 130                 if (init_val->val) {
 131                         status = acpi_os_predefined_override (init_val, &val);
 132                         if (ACPI_FAILURE (status)) {
 133                                 ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
 134                                         "Could not override predefined %s\n",
 135                                         init_val->name));
 136                         }
 137
 138                         if (!val) {
 139                                 val = init_val->val;
 140                         }
 141
 142                         /*
 143                          * Entry requests an initial value, allocate a
 144                          * descriptor for it.
 145                          */
 146                         obj_desc = acpi_ut_create_internal_object (init_val->type);
 147                         if (!obj_desc) {
 148                                 status = AE_NO_MEMORY;
 149                                 goto unlock_and_exit;
 150                         }
 151
 152                         /*
 153                          * Convert value string from table entry to
 154                          * internal representation. Only types actually
 155                          * used for initial values are implemented here.
 156                          */
 157                         switch (init_val->type) {
 158                         case ACPI_TYPE_METHOD:
 159                                 obj_desc->method.param_count = (u8) ACPI_TO_INTEGER (val);
 160                                 obj_desc->common.flags |= AOPOBJ_DATA_VALID;
 161
 162 #if defined (ACPI_ASL_COMPILER) || defined (ACPI_DUMP_App)
 163
 164                                 /*
 165                                  * i_aSL Compiler cheats by putting parameter count
 166                                  * in the owner_iD
 167                                  */
 168                                 new_node->owner_id = obj_desc->method.param_count;
 169 #else
 170                                 /* Mark this as a very SPECIAL method */
 171
 172                                 obj_desc->method.method_flags = AML_METHOD_INTERNAL_ONLY;
 173                                 obj_desc->method.implementation = acpi_ut_osi_implementation;
 174 #endif
 175                                 break;
 176
 177                         case ACPI_TYPE_INTEGER:
 178
 179                                 obj_desc->integer.value = ACPI_TO_INTEGER (val);
 180                                 break;
 181
 182
 183                         case ACPI_TYPE_STRING:
 184
 185                                 /*
 186                                  * Build an object around the static string
 187                                  */
 188                                 obj_desc->string.length = (u32) ACPI_STRLEN (val);
 189                                 obj_desc->string.pointer = val;
 190                                 obj_desc->common.flags |= AOPOBJ_STATIC_POINTER;
 191                                 break;
 192
 193
 194                         case ACPI_TYPE_MUTEX:
 195
 196                                 obj_desc->mutex.node = new_node;
 197                                 obj_desc->mutex.sync_level = (u8) (ACPI_TO_INTEGER (val) - 1);
 198
 199                                 if (ACPI_STRCMP (init_val->name, "_GL_") == 0) {
 200                                         /*
 201                                          * Create a counting semaphore for the
 202                                          * global lock
 203                                          */
 204                                         status = acpi_os_create_semaphore (ACPI_NO_UNIT_LIMIT,
 205                                                          1, &obj_desc->mutex.semaphore);
 206                                         if (ACPI_FAILURE (status)) {
 207                                                 acpi_ut_remove_reference (obj_desc);
 208                                                 goto unlock_and_exit;
 209                                         }
 210
 211                                         /*
 212                                          * We just created the mutex for the
 213                                          * global lock, save it
 214                                          */
 215                                         acpi_gbl_global_lock_semaphore = obj_desc->mutex.semaphore;
 216                                 }
 217                                 else {
 218                                         /* Create a mutex */
 219
 220                                         status = acpi_os_create_semaphore (1, 1,
 221                                                            &obj_desc->mutex.semaphore);
 222                                         if (ACPI_FAILURE (status)) {
 223                                                 acpi_ut_remove_reference (obj_desc);
 224                                                 goto unlock_and_exit;
 225                                         }
 226                                 }
 227                                 break;
 228
 229
 230                         default:
 231
 232                                 ACPI_REPORT_ERROR (("Unsupported initial type value %X\n",
 233                                         init_val->type));
 234                                 acpi_ut_remove_reference (obj_desc);
 235                                 obj_desc = NULL;
 236                                 continue;
 237                         }
 238
 239                         /* Store pointer to value descriptor in the Node */
 240
 241                         status = acpi_ns_attach_object (new_node, obj_desc,
 242                                          ACPI_GET_OBJECT_TYPE (obj_desc));
 243
 244                         /* Remove local reference to the object */
 245
 246                         acpi_ut_remove_reference (obj_desc);
 247                 }
 248         }
 249
 250
 251 unlock_and_exit:
 252         (void) acpi_ut_release_mutex (ACPI_MTX_NAMESPACE);
 253
 254         /* Save a handle to "_GPE", it is always present */
 255
 256         if (ACPI_SUCCESS (status)) {
 257                 status = acpi_ns_get_node_by_path ("\\_GPE", NULL, ACPI_NS_NO_UPSEARCH,
 258                                   &acpi_gbl_fadt_gpe_device);
 259         }
 260
 261         return_ACPI_STATUS (status);
 262 }
 263
 264
 265 /*******************************************************************************
 266  *
 267  * FUNCTION:    acpi_ns_lookup
 268  *
 269  * PARAMETERS:  scope_info      - Current scope info block
 270  *              Pathname        - Search pathname, in internal format
 271  *                                (as represented in the AML stream)
 272  *              Type            - Type associated with name
 273  *              interpreter_mode - IMODE_LOAD_PASS2 => add name if not found
 274  *              Flags           - Flags describing the search restrictions
 275  *              walk_state      - Current state of the walk
 276  *              return_node     - Where the Node is placed (if found
 277  *                                or created successfully)
 278  *
 279  * RETURN:      Status
 280  *
 281  * DESCRIPTION: Find or enter the passed name in the name space.
 282  *              Log an error if name not found in Exec mode.
 283  *
 284  * MUTEX:       Assumes namespace is locked.
 285  *
 286  ******************************************************************************/
 287
 288 acpi_status
 289 acpi_ns_lookup (
 290         union acpi_generic_state        *scope_info,
 291         char                            *pathname,
 292         acpi_object_type                type,
 293         acpi_interpreter_mode           interpreter_mode,
 294         u32                             flags,
 295         struct acpi_walk_state          *walk_state,
 296         struct acpi_namespace_node      **return_node)
 297 {
 298         acpi_status                     status;
 299         char                            *path = pathname;
 300         struct acpi_namespace_node      *prefix_node;
 301         struct acpi_namespace_node      *current_node = NULL;
 302         struct acpi_namespace_node      *this_node = NULL;
 303         u32                             num_segments;
 304         u32                             num_carats;
 305         acpi_name                       simple_name;
 306         acpi_object_type                type_to_check_for;
 307         acpi_object_type                this_search_type;
 308         u32                             search_parent_flag = ACPI_NS_SEARCH_PARENT;
 309         u32                             local_flags = flags & ~(ACPI_NS_ERROR_IF_FOUND |
 310                            ACPI_NS_SEARCH_PARENT);
 311
 312
 313         ACPI_FUNCTION_TRACE ("ns_lookup");
 314
 315
 316         if (!return_node) {
 317                 return_ACPI_STATUS (AE_BAD_PARAMETER);
 318         }
 319
 320         acpi_gbl_ns_lookup_count++;
 321         *return_node = ACPI_ENTRY_NOT_FOUND;
 322
 323         if (!acpi_gbl_root_node) {
 324                 return_ACPI_STATUS (AE_NO_NAMESPACE);
 325         }
 326
 327         /*
 328          * Get the prefix scope.
 329          * A null scope means use the root scope
 330          */
 331         if ((!scope_info) ||
 332                 (!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         }
 339         else {
 340                 prefix_node = scope_info->scope.node;
 341                 if (ACPI_GET_DESCRIPTOR_TYPE (prefix_node) != ACPI_DESC_TYPE_NAMED) {
 342                         ACPI_REPORT_ERROR (("ns_lookup: %p is not a namespace node [%s]\n",
 343                                         prefix_node, acpi_ut_get_descriptor_name (prefix_node)));
 344                         return_ACPI_STATUS (AE_AML_INTERNAL);
 345                 }
 346
 347                 /*
 348                  * This node might not be a actual "scope" node (such as a
 349                  * Device/Method, etc.)  It could be a Package or other object node.
 350                  * Backup up the tree to find the containing scope node.
 351                  */
 352                 while (!acpi_ns_opens_scope (prefix_node->type) &&
 353                                 prefix_node->type != ACPI_TYPE_ANY) {
 354                         prefix_node = acpi_ns_get_parent_node (prefix_node);
 355                 }
 356         }
 357
 358         /* Save type   TBD: may be no longer necessary */
 359
 360         type_to_check_for = type;
 361
 362         /*
 363          * Begin examination of the actual pathname
 364          */
 365         if (!pathname) {
 366                 /* A Null name_path is allowed and refers to the root */
 367
 368                 num_segments = 0;
 369                 this_node    = acpi_gbl_root_node;
 370                 path     = "";
 371
 372                 ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
 373                         "Null Pathname (Zero segments), Flags=%X\n", flags));
 374         }
 375         else {
 376                 /*
 377                  * Name pointer is valid (and must be in internal name format)
 378                  *
 379                  * Check for scope prefixes:
 380                  *
 381                  * As represented in the AML stream, a namepath consists of an
 382                  * optional scope prefix followed by a name segment part.
 383                  *
 384                  * If present, the scope prefix is either a Root Prefix (in
 385                  * which case the name is fully qualified), or one or more
 386                  * Parent Prefixes (in which case the name's scope is relative
 387                  * to the current scope).
 388                  */
 389                 if (*path == (u8) AML_ROOT_PREFIX) {
 390                         /* Pathname is fully qualified, start from the root */
 391
 392                         this_node = acpi_gbl_root_node;
 393                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 394
 395                         /* Point to name segment part */
 396
 397                         path++;
 398
 399                         ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
 400                                 "Path is absolute from root [%p]\n", this_node));
 401                 }
 402                 else {
 403                         /* Pathname is relative to current scope, start there */
 404
 405                         ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
 406                                 "Searching relative to prefix scope [%4.4s] (%p)\n",
 407                                 acpi_ut_get_node_name (prefix_node), 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 (
 433                                                 ("ACPI path has too many parent prefixes (^) - reached beyond root node\n"));
 434                                         return_ACPI_STATUS (AE_NOT_FOUND);
 435                                 }
 436                         }
 437
 438                         if (search_parent_flag == ACPI_NS_NO_UPSEARCH) {
 439                                 ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
 440                                         "Search scope is [%4.4s], path has %d carat(s)\n",
 441                                         acpi_ut_get_node_name (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", flags));
 485                         break;
 486
 487                 case AML_MULTI_NAME_PREFIX_OP:
 488
 489                         /* More than one name_seg, search rules do not apply */
 490
 491                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 492
 493                         /* Extract segment count, point to first name segment */
 494
 495                         path++;
 496                         num_segments = (u32) (u8) *path;
 497                         path++;
 498
 499                         ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
 500                                 "Multi Pathname (%d Segments, Flags=%X) \n",
 501                                 num_segments, flags));
 502                         break;
 503
 504                 default:
 505                         /*
 506                          * Not a Null name, no Dual or Multi prefix, hence there is
 507                          * only one name segment and Pathname is already pointing to it.
 508                          */
 509                         num_segments = 1;
 510
 511                         ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
 512                                 "Simple Pathname (1 segment, Flags=%X)\n", flags));
 513                         break;
 514                 }
 515
 516                 ACPI_DEBUG_EXEC (acpi_ns_print_pathname (num_segments, path));
 517         }
 518
 519
 520         /*
 521          * Search namespace for each segment of the name.  Loop through and
 522          * verify (or add to the namespace) each name segment.
 523          *
 524          * The object type is significant only at the last name
 525          * segment.  (We don't care about the types along the path, only
 526          * the type of the final target object.)
 527          */
 528         this_search_type = ACPI_TYPE_ANY;
 529         current_node = this_node;
 530         while (num_segments && current_node) {
 531                 num_segments--;
 532                 if (!num_segments) {
 533                         /*
 534                          * This is the last segment, enable typechecking
 535                          */
 536                         this_search_type = type;
 537
 538                         /*
 539                          * Only allow automatic parent search (search rules) if the caller
 540                          * requested it AND we have a single, non-fully-qualified name_seg
 541                          */
 542                         if ((search_parent_flag != ACPI_NS_NO_UPSEARCH) &&
 543                                 (flags & ACPI_NS_SEARCH_PARENT)) {
 544                                 local_flags |= ACPI_NS_SEARCH_PARENT;
 545                         }
 546
 547                         /* Set error flag according to caller */
 548
 549                         if (flags & ACPI_NS_ERROR_IF_FOUND) {
 550                                 local_flags |= ACPI_NS_ERROR_IF_FOUND;
 551                         }
 552                 }
 553
 554                 /* Extract one ACPI name from the front of the pathname */
 555
 556                 ACPI_MOVE_32_TO_32 (&simple_name, path);
 557
 558                 /* Try to find the single (4 character) ACPI name */
 559
 560                 status = acpi_ns_search_and_enter (simple_name, walk_state, current_node,
 561                                  interpreter_mode, this_search_type, local_flags, &this_node);
 562                 if (ACPI_FAILURE (status)) {
 563                         if (status == AE_NOT_FOUND) {
 564                                 /* Name not found in ACPI namespace */
 565
 566                                 ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
 567                                         "Name [%4.4s] not found in scope [%4.4s] %p\n",
 568                                         (char *) &simple_name, (char *) &current_node->name,
 569                                         current_node));
 570                         }
 571
 572                         *return_node = this_node;
 573                         return_ACPI_STATUS (status);
 574                 }
 575
 576                 /*
 577                  * Sanity typecheck of the target object:
 578                  *
 579                  * If 1) This is the last segment (num_segments == 0)
 580                  *    2) And we are looking for a specific type
 581                  *       (Not checking for TYPE_ANY)
 582                  *    3) Which is not an alias
 583                  *    4) Which is not a local type (TYPE_SCOPE)
 584                  *    5) And the type of target object is known (not TYPE_ANY)
 585                  *    6) And target object does not match what we are looking for
 586                  *
 587                  * Then we have a type mismatch.  Just warn and ignore it.
 588                  */
 589                 if ((num_segments       == 0)                               &&
 590                         (type_to_check_for  != ACPI_TYPE_ANY)                   &&
 591                         (type_to_check_for  != ACPI_TYPE_LOCAL_ALIAS)           &&
 592                         (type_to_check_for  != ACPI_TYPE_LOCAL_METHOD_ALIAS)    &&
 593                         (type_to_check_for  != ACPI_TYPE_LOCAL_SCOPE)           &&
 594                         (this_node->type    != ACPI_TYPE_ANY)                   &&
 595                         (this_node->type    != type_to_check_for)) {
 596                         /* Complain about a type mismatch */
 597
 598                         ACPI_REPORT_WARNING (
 599                                 ("ns_lookup: Type mismatch on %4.4s (%s), searching for (%s)\n",
 600                                 (char *) &simple_name, acpi_ut_get_type_name (this_node->type),
 601                                 acpi_ut_get_type_name (type_to_check_for)));
 602                 }
 603
 604                 /*
 605                  * If this is the last name segment and we are not looking for a
 606                  * specific type, but the type of found object is known, use that type
 607                  * to see if it opens a scope.
 608                  */
 609                 if ((num_segments == 0) && (type == ACPI_TYPE_ANY)) {
 610                         type = this_node->type;
 611                 }
 612
 613                 /* Point to next name segment and make this node current */
 614
 615                 path += ACPI_NAME_SIZE;
 616                 current_node = this_node;
 617         }
 618
 619         /*
 620          * Always check if we need to open a new scope
 621          */
 622         if (!(flags & ACPI_NS_DONT_OPEN_SCOPE) && (walk_state)) {
 623                 /*
 624                  * If entry is a type which opens a scope, push the new scope on the
 625                  * scope stack.
 626                  */
 627                 if (acpi_ns_opens_scope (type)) {
 628                         status = acpi_ds_scope_stack_push (this_node, type, walk_state);
 629                         if (ACPI_FAILURE (status)) {
 630                                 return_ACPI_STATUS (status);
 631                         }
 632                 }
 633         }
 634
 635         *return_node = this_node;
 636         return_ACPI_STATUS (AE_OK);
 637 }
 638