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 - 2006, 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
 102                 /* _OSI is optional for now, will be permanent later */
 103
 104                 if (!ACPI_STRCMP(init_val->name, "_OSI")
 105                     && !acpi_gbl_create_osi_method) {
 106                         continue;
 107                 }
 108
 109                 status = acpi_ns_lookup(NULL, init_val->name, init_val->type,
 110                                         ACPI_IMODE_LOAD_PASS2,
 111                                         ACPI_NS_NO_UPSEARCH, NULL, &new_node);
 112
 113                 if (ACPI_FAILURE(status) || (!new_node)) {      /* Must be on same line for code converter */
 114                         ACPI_EXCEPTION((AE_INFO, status,
 115                                         "Could not create predefined name %s",
 116                                         init_val->name));
 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_ERROR((AE_INFO,
 128                                             "Could not override predefined %s",
 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_ERROR((AE_INFO,
 237                                             "Unsupported initial type value %X",
 238                                             init_val->type));
 239                                 acpi_ut_remove_reference(obj_desc);
 240                                 obj_desc = NULL;
 241                                 continue;
 242                         }
 243
 244                         /* Store pointer to value descriptor in the Node */
 245
 246                         status = acpi_ns_attach_object(new_node, obj_desc,
 247                                                        ACPI_GET_OBJECT_TYPE
 248                                                        (obj_desc));
 249
 250                         /* Remove local reference to the object */
 251
 252                         acpi_ut_remove_reference(obj_desc);
 253                 }
 254         }
 255
 256       unlock_and_exit:
 257         (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
 258
 259         /* Save a handle to "_GPE", it is always present */
 260
 261         if (ACPI_SUCCESS(status)) {
 262                 status =
 263                     acpi_ns_get_node_by_path("\\_GPE", NULL,
 264                                              ACPI_NS_NO_UPSEARCH,
 265                                              &acpi_gbl_fadt_gpe_device);
 266         }
 267
 268         return_ACPI_STATUS(status);
 269 }
 270
 271 /*******************************************************************************
 272  *
 273  * FUNCTION:    acpi_ns_lookup
 274  *
 275  * PARAMETERS:  scope_info      - Current scope info block
 276  *              Pathname        - Search pathname, in internal format
 277  *                                (as represented in the AML stream)
 278  *              Type            - Type associated with name
 279  *              interpreter_mode - IMODE_LOAD_PASS2 => add name if not found
 280  *              Flags           - Flags describing the search restrictions
 281  *              walk_state      - Current state of the walk
 282  *              return_node     - Where the Node is placed (if found
 283  *                                or created successfully)
 284  *
 285  * RETURN:      Status
 286  *
 287  * DESCRIPTION: Find or enter the passed name in the name space.
 288  *              Log an error if name not found in Exec mode.
 289  *
 290  * MUTEX:       Assumes namespace is locked.
 291  *
 292  ******************************************************************************/
 293
 294 acpi_status
 295 acpi_ns_lookup(union acpi_generic_state *scope_info,
 296                char *pathname,
 297                acpi_object_type type,
 298                acpi_interpreter_mode interpreter_mode,
 299                u32 flags,
 300                struct acpi_walk_state *walk_state,
 301                struct acpi_namespace_node **return_node)
 302 {
 303         acpi_status status;
 304         char *path = pathname;
 305         struct acpi_namespace_node *prefix_node;
 306         struct acpi_namespace_node *current_node = NULL;
 307         struct acpi_namespace_node *this_node = NULL;
 308         u32 num_segments;
 309         u32 num_carats;
 310         acpi_name simple_name;
 311         acpi_object_type type_to_check_for;
 312         acpi_object_type this_search_type;
 313         u32 search_parent_flag = ACPI_NS_SEARCH_PARENT;
 314         u32 local_flags = flags & ~(ACPI_NS_ERROR_IF_FOUND |
 315                                     ACPI_NS_SEARCH_PARENT);
 316
 317         ACPI_FUNCTION_TRACE(ns_lookup);
 318
 319         if (!return_node) {
 320                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 321         }
 322
 323         acpi_gbl_ns_lookup_count++;
 324         *return_node = ACPI_ENTRY_NOT_FOUND;
 325
 326         if (!acpi_gbl_root_node) {
 327                 return_ACPI_STATUS(AE_NO_NAMESPACE);
 328         }
 329
 330         /*
 331          * Get the prefix scope.
 332          * A null scope means use the root scope
 333          */
 334         if ((!scope_info) || (!scope_info->scope.node)) {
 335                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 336                                   "Null scope prefix, using root node (%p)\n",
 337                                   acpi_gbl_root_node));
 338
 339                 prefix_node = acpi_gbl_root_node;
 340         } else {
 341                 prefix_node = scope_info->scope.node;
 342                 if (ACPI_GET_DESCRIPTOR_TYPE(prefix_node) !=
 343                     ACPI_DESC_TYPE_NAMED) {
 344                         ACPI_ERROR((AE_INFO, "%p is not a namespace node [%s]",
 345                                     prefix_node,
 346                                     acpi_ut_get_descriptor_name(prefix_node)));
 347                         return_ACPI_STATUS(AE_AML_INTERNAL);
 348                 }
 349
 350                 if (!(flags & ACPI_NS_PREFIX_IS_SCOPE)) {
 351                         /*
 352                          * This node might not be a actual "scope" node (such as a
 353                          * Device/Method, etc.)  It could be a Package or other object node.
 354                          * Backup up the tree to find the containing scope node.
 355                          */
 356                         while (!acpi_ns_opens_scope(prefix_node->type) &&
 357                                prefix_node->type != ACPI_TYPE_ANY) {
 358                                 prefix_node =
 359                                     acpi_ns_get_parent_node(prefix_node);
 360                         }
 361                 }
 362         }
 363
 364         /* Save type   TBD: may be no longer necessary */
 365
 366         type_to_check_for = type;
 367
 368         /*
 369          * Begin examination of the actual pathname
 370          */
 371         if (!pathname) {
 372
 373                 /* A Null name_path is allowed and refers to the root */
 374
 375                 num_segments = 0;
 376                 this_node = acpi_gbl_root_node;
 377                 path = "";
 378
 379                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 380                                   "Null Pathname (Zero segments), Flags=%X\n",
 381                                   flags));
 382         } else {
 383                 /*
 384                  * Name pointer is valid (and must be in internal name format)
 385                  *
 386                  * Check for scope prefixes:
 387                  *
 388                  * As represented in the AML stream, a namepath consists of an
 389                  * optional scope prefix followed by a name segment part.
 390                  *
 391                  * If present, the scope prefix is either a Root Prefix (in
 392                  * which case the name is fully qualified), or one or more
 393                  * Parent Prefixes (in which case the name's scope is relative
 394                  * to the current scope).
 395                  */
 396                 if (*path == (u8) AML_ROOT_PREFIX) {
 397
 398                         /* Pathname is fully qualified, start from the root */
 399
 400                         this_node = acpi_gbl_root_node;
 401                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 402
 403                         /* Point to name segment part */
 404
 405                         path++;
 406
 407                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 408                                           "Path is absolute from root [%p]\n",
 409                                           this_node));
 410                 } else {
 411                         /* Pathname is relative to current scope, start there */
 412
 413                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 414                                           "Searching relative to prefix scope [%4.4s] (%p)\n",
 415                                           acpi_ut_get_node_name(prefix_node),
 416                                           prefix_node));
 417
 418                         /*
 419                          * Handle multiple Parent Prefixes (carat) by just getting
 420                          * the parent node for each prefix instance.
 421                          */
 422                         this_node = prefix_node;
 423                         num_carats = 0;
 424                         while (*path == (u8) AML_PARENT_PREFIX) {
 425
 426                                 /* Name is fully qualified, no search rules apply */
 427
 428                                 search_parent_flag = ACPI_NS_NO_UPSEARCH;
 429                                 /*
 430                                  * Point past this prefix to the name segment
 431                                  * part or the next Parent Prefix
 432                                  */
 433                                 path++;
 434
 435                                 /* Backup to the parent node */
 436
 437                                 num_carats++;
 438                                 this_node = acpi_ns_get_parent_node(this_node);
 439                                 if (!this_node) {
 440
 441                                         /* Current scope has no parent scope */
 442
 443                                         ACPI_ERROR((AE_INFO,
 444                                                     "ACPI path has too many parent prefixes (^) - reached beyond root node"));
 445                                         return_ACPI_STATUS(AE_NOT_FOUND);
 446                                 }
 447                         }
 448
 449                         if (search_parent_flag == ACPI_NS_NO_UPSEARCH) {
 450                                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 451                                                   "Search scope is [%4.4s], path has %d carat(s)\n",
 452                                                   acpi_ut_get_node_name
 453                                                   (this_node), num_carats));
 454                         }
 455                 }
 456
 457                 /*
 458                  * Determine the number of ACPI name segments in this pathname.
 459                  *
 460                  * The segment part consists of either:
 461                  *  - A Null name segment (0)
 462                  *  - A dual_name_prefix followed by two 4-byte name segments
 463                  *  - A multi_name_prefix followed by a byte indicating the
 464                  *      number of segments and the segments themselves.
 465                  *  - A single 4-byte name segment
 466                  *
 467                  * Examine the name prefix opcode, if any, to determine the number of
 468                  * segments.
 469                  */
 470                 switch (*path) {
 471                 case 0:
 472                         /*
 473                          * Null name after a root or parent prefixes. We already
 474                          * have the correct target node and there are no name segments.
 475                          */
 476                         num_segments = 0;
 477                         type = this_node->type;
 478
 479                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 480                                           "Prefix-only Pathname (Zero name segments), Flags=%X\n",
 481                                           flags));
 482                         break;
 483
 484                 case AML_DUAL_NAME_PREFIX:
 485
 486                         /* More than one name_seg, search rules do not apply */
 487
 488                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 489
 490                         /* Two segments, point to first name segment */
 491
 492                         num_segments = 2;
 493                         path++;
 494
 495                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 496                                           "Dual Pathname (2 segments, Flags=%X)\n",
 497                                           flags));
 498                         break;
 499
 500                 case AML_MULTI_NAME_PREFIX_OP:
 501
 502                         /* More than one name_seg, search rules do not apply */
 503
 504                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 505
 506                         /* Extract segment count, point to first name segment */
 507
 508                         path++;
 509                         num_segments = (u32) (u8) * path;
 510                         path++;
 511
 512                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 513                                           "Multi Pathname (%d Segments, Flags=%X)\n",
 514                                           num_segments, flags));
 515                         break;
 516
 517                 default:
 518                         /*
 519                          * Not a Null name, no Dual or Multi prefix, hence there is
 520                          * only one name segment and Pathname is already pointing to it.
 521                          */
 522                         num_segments = 1;
 523
 524                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 525                                           "Simple Pathname (1 segment, Flags=%X)\n",
 526                                           flags));
 527                         break;
 528                 }
 529
 530                 ACPI_DEBUG_EXEC(acpi_ns_print_pathname(num_segments, path));
 531         }
 532
 533         /*
 534          * Search namespace for each segment of the name.  Loop through and
 535          * verify (or add to the namespace) each name segment.
 536          *
 537          * The object type is significant only at the last name
 538          * segment.  (We don't care about the types along the path, only
 539          * the type of the final target object.)
 540          */
 541         this_search_type = ACPI_TYPE_ANY;
 542         current_node = this_node;
 543         while (num_segments && current_node) {
 544                 num_segments--;
 545                 if (!num_segments) {
 546                         /*
 547                          * This is the last segment, enable typechecking
 548                          */
 549                         this_search_type = type;
 550
 551                         /*
 552                          * Only allow automatic parent search (search rules) if the caller
 553                          * requested it AND we have a single, non-fully-qualified name_seg
 554                          */
 555                         if ((search_parent_flag != ACPI_NS_NO_UPSEARCH) &&
 556                             (flags & ACPI_NS_SEARCH_PARENT)) {
 557                                 local_flags |= ACPI_NS_SEARCH_PARENT;
 558                         }
 559
 560                         /* Set error flag according to caller */
 561
 562                         if (flags & ACPI_NS_ERROR_IF_FOUND) {
 563                                 local_flags |= ACPI_NS_ERROR_IF_FOUND;
 564                         }
 565                 }
 566
 567                 /* Extract one ACPI name from the front of the pathname */
 568
 569                 ACPI_MOVE_32_TO_32(&simple_name, path);
 570
 571                 /* Try to find the single (4 character) ACPI name */
 572
 573                 status =
 574                     acpi_ns_search_and_enter(simple_name, walk_state,
 575                                              current_node, interpreter_mode,
 576                                              this_search_type, local_flags,
 577                                              &this_node);
 578                 if (ACPI_FAILURE(status)) {
 579                         if (status == AE_NOT_FOUND) {
 580
 581                                 /* Name not found in ACPI namespace */
 582
 583                                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 584                                                   "Name [%4.4s] not found in scope [%4.4s] %p\n",
 585                                                   (char *)&simple_name,
 586                                                   (char *)&current_node->name,
 587                                                   current_node));
 588                         }
 589
 590                         *return_node = this_node;
 591                         return_ACPI_STATUS(status);
 592                 }
 593
 594                 /*
 595                  * Sanity typecheck of the target object:
 596                  *
 597                  * If 1) This is the last segment (num_segments == 0)
 598                  *    2) And we are looking for a specific type
 599                  *       (Not checking for TYPE_ANY)
 600                  *    3) Which is not an alias
 601                  *    4) Which is not a local type (TYPE_SCOPE)
 602                  *    5) And the type of target object is known (not TYPE_ANY)
 603                  *    6) And target object does not match what we are looking for
 604                  *
 605                  * Then we have a type mismatch.  Just warn and ignore it.
 606                  */
 607                 if ((num_segments == 0) &&
 608                     (type_to_check_for != ACPI_TYPE_ANY) &&
 609                     (type_to_check_for != ACPI_TYPE_LOCAL_ALIAS) &&
 610                     (type_to_check_for != ACPI_TYPE_LOCAL_METHOD_ALIAS) &&
 611                     (type_to_check_for != ACPI_TYPE_LOCAL_SCOPE) &&
 612                     (this_node->type != ACPI_TYPE_ANY) &&
 613                     (this_node->type != type_to_check_for)) {
 614
 615                         /* Complain about a type mismatch */
 616
 617                         ACPI_WARNING((AE_INFO,
 618                                       "NsLookup: Type mismatch on %4.4s (%s), searching for (%s)",
 619                                       ACPI_CAST_PTR(char, &simple_name),
 620                                       acpi_ut_get_type_name(this_node->type),
 621                                       acpi_ut_get_type_name
 622                                       (type_to_check_for)));
 623                 }
 624
 625                 /*
 626                  * If this is the last name segment and we are not looking for a
 627                  * specific type, but the type of found object is known, use that type
 628                  * to see if it opens a scope.
 629                  */
 630                 if ((num_segments == 0) && (type == ACPI_TYPE_ANY)) {
 631                         type = this_node->type;
 632                 }
 633
 634                 /* Point to next name segment and make this node current */
 635
 636                 path += ACPI_NAME_SIZE;
 637                 current_node = this_node;
 638         }
 639
 640         /*
 641          * Always check if we need to open a new scope
 642          */
 643         if (!(flags & ACPI_NS_DONT_OPEN_SCOPE) && (walk_state)) {
 644                 /*
 645                  * If entry is a type which opens a scope, push the new scope on the
 646                  * scope stack.
 647                  */
 648                 if (acpi_ns_opens_scope(type)) {
 649                         status =
 650                             acpi_ds_scope_stack_push(this_node, type,
 651                                                      walk_state);
 652                         if (ACPI_FAILURE(status)) {
 653                                 return_ACPI_STATUS(status);
 654                         }
 655                 }
 656         }
 657
 658         *return_node = this_node;
 659         return_ACPI_STATUS(AE_OK);
 660 }