drivers/acpi/acpica/dsmethod.c

   1 /******************************************************************************
   2  *
   3  * Module Name: dsmethod - Parser/Interpreter interface - control method parsing
   4  *
   5  *****************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2013, Intel Corp.
   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 "accommon.h"
  46 #include "acdispat.h"
  47 #include "acinterp.h"
  48 #include "acnamesp.h"
  49 #ifdef  ACPI_DISASSEMBLER
  50 #include "acdisasm.h"
  51 #endif
  52
  53 #define _COMPONENT          ACPI_DISPATCHER
  54 ACPI_MODULE_NAME("dsmethod")
  55
  56 /* Local prototypes */
  57 static acpi_status
  58 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc);
  59
  60 /*******************************************************************************
  61  *
  62  * FUNCTION:    acpi_ds_method_error
  63  *
  64  * PARAMETERS:  status          - Execution status
  65  *              walk_state      - Current state
  66  *
  67  * RETURN:      Status
  68  *
  69  * DESCRIPTION: Called on method error. Invoke the global exception handler if
  70  *              present, dump the method data if the disassembler is configured
  71  *
  72  *              Note: Allows the exception handler to change the status code
  73  *
  74  ******************************************************************************/
  75
  76 acpi_status
  77 acpi_ds_method_error(acpi_status status, struct acpi_walk_state *walk_state)
  78 {
  79         ACPI_FUNCTION_ENTRY();
  80
  81         /* Ignore AE_OK and control exception codes */
  82
  83         if (ACPI_SUCCESS(status) || (status & AE_CODE_CONTROL)) {
  84                 return (status);
  85         }
  86
  87         /* Invoke the global exception handler */
  88
  89         if (acpi_gbl_exception_handler) {
  90
  91                 /* Exit the interpreter, allow handler to execute methods */
  92
  93                 acpi_ex_exit_interpreter();
  94
  95                 /*
  96                  * Handler can map the exception code to anything it wants, including
  97                  * AE_OK, in which case the executing method will not be aborted.
  98                  */
  99                 status = acpi_gbl_exception_handler(status,
 100                                                     walk_state->method_node ?
 101                                                     walk_state->method_node->
 102                                                     name.integer : 0,
 103                                                     walk_state->opcode,
 104                                                     walk_state->aml_offset,
 105                                                     NULL);
 106                 acpi_ex_enter_interpreter();
 107         }
 108
 109         acpi_ds_clear_implicit_return(walk_state);
 110
 111 #ifdef ACPI_DISASSEMBLER
 112         if (ACPI_FAILURE(status)) {
 113
 114                 /* Display method locals/args if disassembler is present */
 115
 116                 acpi_dm_dump_method_info(status, walk_state, walk_state->op);
 117         }
 118 #endif
 119
 120         return (status);
 121 }
 122
 123 /*******************************************************************************
 124  *
 125  * FUNCTION:    acpi_ds_create_method_mutex
 126  *
 127  * PARAMETERS:  obj_desc            - The method object
 128  *
 129  * RETURN:      Status
 130  *
 131  * DESCRIPTION: Create a mutex object for a serialized control method
 132  *
 133  ******************************************************************************/
 134
 135 static acpi_status
 136 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc)
 137 {
 138         union acpi_operand_object *mutex_desc;
 139         acpi_status status;
 140
 141         ACPI_FUNCTION_TRACE(ds_create_method_mutex);
 142
 143         /* Create the new mutex object */
 144
 145         mutex_desc = acpi_ut_create_internal_object(ACPI_TYPE_MUTEX);
 146         if (!mutex_desc) {
 147                 return_ACPI_STATUS(AE_NO_MEMORY);
 148         }
 149
 150         /* Create the actual OS Mutex */
 151
 152         status = acpi_os_create_mutex(&mutex_desc->mutex.os_mutex);
 153         if (ACPI_FAILURE(status)) {
 154                 acpi_ut_delete_object_desc(mutex_desc);
 155                 return_ACPI_STATUS(status);
 156         }
 157
 158         mutex_desc->mutex.sync_level = method_desc->method.sync_level;
 159         method_desc->method.mutex = mutex_desc;
 160         return_ACPI_STATUS(AE_OK);
 161 }
 162
 163 /*******************************************************************************
 164  *
 165  * FUNCTION:    acpi_ds_begin_method_execution
 166  *
 167  * PARAMETERS:  method_node         - Node of the method
 168  *              obj_desc            - The method object
 169  *              walk_state          - current state, NULL if not yet executing
 170  *                                    a method.
 171  *
 172  * RETURN:      Status
 173  *
 174  * DESCRIPTION: Prepare a method for execution. Parses the method if necessary,
 175  *              increments the thread count, and waits at the method semaphore
 176  *              for clearance to execute.
 177  *
 178  ******************************************************************************/
 179
 180 acpi_status
 181 acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
 182                                union acpi_operand_object *obj_desc,
 183                                struct acpi_walk_state *walk_state)
 184 {
 185         acpi_status status = AE_OK;
 186
 187         ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);
 188
 189         if (!method_node) {
 190                 return_ACPI_STATUS(AE_NULL_ENTRY);
 191         }
 192
 193         /* Prevent wraparound of thread count */
 194
 195         if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {
 196                 ACPI_ERROR((AE_INFO,
 197                             "Method reached maximum reentrancy limit (255)"));
 198                 return_ACPI_STATUS(AE_AML_METHOD_LIMIT);
 199         }
 200
 201         /*
 202          * If this method is serialized, we need to acquire the method mutex.
 203          */
 204         if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {
 205                 /*
 206                  * Create a mutex for the method if it is defined to be Serialized
 207                  * and a mutex has not already been created. We defer the mutex creation
 208                  * until a method is actually executed, to minimize the object count
 209                  */
 210                 if (!obj_desc->method.mutex) {
 211                         status = acpi_ds_create_method_mutex(obj_desc);
 212                         if (ACPI_FAILURE(status)) {
 213                                 return_ACPI_STATUS(status);
 214                         }
 215                 }
 216
 217                 /*
 218                  * The current_sync_level (per-thread) must be less than or equal to
 219                  * the sync level of the method. This mechanism provides some
 220                  * deadlock prevention
 221                  *
 222                  * Top-level method invocation has no walk state at this point
 223                  */
 224                 if (walk_state &&
 225                     (walk_state->thread->current_sync_level >
 226                      obj_desc->method.mutex->mutex.sync_level)) {
 227                         ACPI_ERROR((AE_INFO,
 228                                     "Cannot acquire Mutex for method [%4.4s], current SyncLevel is too large (%u)",
 229                                     acpi_ut_get_node_name(method_node),
 230                                     walk_state->thread->current_sync_level));
 231
 232                         return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
 233                 }
 234
 235                 /*
 236                  * Obtain the method mutex if necessary. Do not acquire mutex for a
 237                  * recursive call.
 238                  */
 239                 if (!walk_state ||
 240                     !obj_desc->method.mutex->mutex.thread_id ||
 241                     (walk_state->thread->thread_id !=
 242                      obj_desc->method.mutex->mutex.thread_id)) {
 243                         /*
 244                          * Acquire the method mutex. This releases the interpreter if we
 245                          * block (and reacquires it before it returns)
 246                          */
 247                         status =
 248                             acpi_ex_system_wait_mutex(obj_desc->method.mutex->
 249                                                       mutex.os_mutex,
 250                                                       ACPI_WAIT_FOREVER);
 251                         if (ACPI_FAILURE(status)) {
 252                                 return_ACPI_STATUS(status);
 253                         }
 254
 255                         /* Update the mutex and walk info and save the original sync_level */
 256
 257                         if (walk_state) {
 258                                 obj_desc->method.mutex->mutex.
 259                                     original_sync_level =
 260                                     walk_state->thread->current_sync_level;
 261
 262                                 obj_desc->method.mutex->mutex.thread_id =
 263                                     walk_state->thread->thread_id;
 264                                 walk_state->thread->current_sync_level =
 265                                     obj_desc->method.sync_level;
 266                         } else {
 267                                 obj_desc->method.mutex->mutex.
 268                                     original_sync_level =
 269                                     obj_desc->method.mutex->mutex.sync_level;
 270
 271                                 obj_desc->method.mutex->mutex.thread_id =
 272                                     acpi_os_get_thread_id();
 273                         }
 274                 }
 275
 276                 /* Always increase acquisition depth */
 277
 278                 obj_desc->method.mutex->mutex.acquisition_depth++;
 279         }
 280
 281         /*
 282          * Allocate an Owner ID for this method, only if this is the first thread
 283          * to begin concurrent execution. We only need one owner_id, even if the
 284          * method is invoked recursively.
 285          */
 286         if (!obj_desc->method.owner_id) {
 287                 status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);
 288                 if (ACPI_FAILURE(status)) {
 289                         goto cleanup;
 290                 }
 291         }
 292
 293         /*
 294          * Increment the method parse tree thread count since it has been
 295          * reentered one more time (even if it is the same thread)
 296          */
 297         obj_desc->method.thread_count++;
 298         return_ACPI_STATUS(status);
 299
 300       cleanup:
 301         /* On error, must release the method mutex (if present) */
 302
 303         if (obj_desc->method.mutex) {
 304                 acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);
 305         }
 306         return_ACPI_STATUS(status);
 307 }
 308
 309 /*******************************************************************************
 310  *
 311  * FUNCTION:    acpi_ds_call_control_method
 312  *
 313  * PARAMETERS:  thread              - Info for this thread
 314  *              this_walk_state     - Current walk state
 315  *              op                  - Current Op to be walked
 316  *
 317  * RETURN:      Status
 318  *
 319  * DESCRIPTION: Transfer execution to a called control method
 320  *
 321  ******************************************************************************/
 322
 323 acpi_status
 324 acpi_ds_call_control_method(struct acpi_thread_state *thread,
 325                             struct acpi_walk_state *this_walk_state,
 326                             union acpi_parse_object *op)
 327 {
 328         acpi_status status;
 329         struct acpi_namespace_node *method_node;
 330         struct acpi_walk_state *next_walk_state = NULL;
 331         union acpi_operand_object *obj_desc;
 332         struct acpi_evaluate_info *info;
 333         u32 i;
 334
 335         ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);
 336
 337         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 338                           "Calling method %p, currentstate=%p\n",
 339                           this_walk_state->prev_op, this_walk_state));
 340
 341         /*
 342          * Get the namespace entry for the control method we are about to call
 343          */
 344         method_node = this_walk_state->method_call_node;
 345         if (!method_node) {
 346                 return_ACPI_STATUS(AE_NULL_ENTRY);
 347         }
 348
 349         obj_desc = acpi_ns_get_attached_object(method_node);
 350         if (!obj_desc) {
 351                 return_ACPI_STATUS(AE_NULL_OBJECT);
 352         }
 353
 354         /* Init for new method, possibly wait on method mutex */
 355
 356         status = acpi_ds_begin_method_execution(method_node, obj_desc,
 357                                                 this_walk_state);
 358         if (ACPI_FAILURE(status)) {
 359                 return_ACPI_STATUS(status);
 360         }
 361
 362         /* Begin method parse/execution. Create a new walk state */
 363
 364         next_walk_state = acpi_ds_create_walk_state(obj_desc->method.owner_id,
 365                                                     NULL, obj_desc, thread);
 366         if (!next_walk_state) {
 367                 status = AE_NO_MEMORY;
 368                 goto cleanup;
 369         }
 370
 371         /*
 372          * The resolved arguments were put on the previous walk state's operand
 373          * stack. Operands on the previous walk state stack always
 374          * start at index 0. Also, null terminate the list of arguments
 375          */
 376         this_walk_state->operands[this_walk_state->num_operands] = NULL;
 377
 378         /*
 379          * Allocate and initialize the evaluation information block
 380          * TBD: this is somewhat inefficient, should change interface to
 381          * ds_init_aml_walk. For now, keeps this struct off the CPU stack
 382          */
 383         info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
 384         if (!info) {
 385                 status = AE_NO_MEMORY;
 386                 goto cleanup;
 387         }
 388
 389         info->parameters = &this_walk_state->operands[0];
 390
 391         status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,
 392                                        obj_desc->method.aml_start,
 393                                        obj_desc->method.aml_length, info,
 394                                        ACPI_IMODE_EXECUTE);
 395
 396         ACPI_FREE(info);
 397         if (ACPI_FAILURE(status)) {
 398                 goto cleanup;
 399         }
 400
 401         /*
 402          * Delete the operands on the previous walkstate operand stack
 403          * (they were copied to new objects)
 404          */
 405         for (i = 0; i < obj_desc->method.param_count; i++) {
 406                 acpi_ut_remove_reference(this_walk_state->operands[i]);
 407                 this_walk_state->operands[i] = NULL;
 408         }
 409
 410         /* Clear the operand stack */
 411
 412         this_walk_state->num_operands = 0;
 413
 414         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 415                           "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",
 416                           method_node->name.ascii, next_walk_state));
 417
 418         /* Invoke an internal method if necessary */
 419
 420         if (obj_desc->method.info_flags & ACPI_METHOD_INTERNAL_ONLY) {
 421                 status =
 422                     obj_desc->method.dispatch.implementation(next_walk_state);
 423                 if (status == AE_OK) {
 424                         status = AE_CTRL_TERMINATE;
 425                 }
 426         }
 427
 428         return_ACPI_STATUS(status);
 429
 430       cleanup:
 431
 432         /* On error, we must terminate the method properly */
 433
 434         acpi_ds_terminate_control_method(obj_desc, next_walk_state);
 435         if (next_walk_state) {
 436                 acpi_ds_delete_walk_state(next_walk_state);
 437         }
 438
 439         return_ACPI_STATUS(status);
 440 }
 441
 442 /*******************************************************************************
 443  *
 444  * FUNCTION:    acpi_ds_restart_control_method
 445  *
 446  * PARAMETERS:  walk_state          - State for preempted method (caller)
 447  *              return_desc         - Return value from the called method
 448  *
 449  * RETURN:      Status
 450  *
 451  * DESCRIPTION: Restart a method that was preempted by another (nested) method
 452  *              invocation. Handle the return value (if any) from the callee.
 453  *
 454  ******************************************************************************/
 455
 456 acpi_status
 457 acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,
 458                                union acpi_operand_object *return_desc)
 459 {
 460         acpi_status status;
 461         int same_as_implicit_return;
 462
 463         ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);
 464
 465         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 466                           "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",
 467                           acpi_ut_get_node_name(walk_state->method_node),
 468                           walk_state->method_call_op, return_desc));
 469
 470         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 471                           "    ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",
 472                           walk_state->return_used,
 473                           walk_state->results, walk_state));
 474
 475         /* Did the called method return a value? */
 476
 477         if (return_desc) {
 478
 479                 /* Is the implicit return object the same as the return desc? */
 480
 481                 same_as_implicit_return =
 482                     (walk_state->implicit_return_obj == return_desc);
 483
 484                 /* Are we actually going to use the return value? */
 485
 486                 if (walk_state->return_used) {
 487
 488                         /* Save the return value from the previous method */
 489
 490                         status = acpi_ds_result_push(return_desc, walk_state);
 491                         if (ACPI_FAILURE(status)) {
 492                                 acpi_ut_remove_reference(return_desc);
 493                                 return_ACPI_STATUS(status);
 494                         }
 495
 496                         /*
 497                          * Save as THIS method's return value in case it is returned
 498                          * immediately to yet another method
 499                          */
 500                         walk_state->return_desc = return_desc;
 501                 }
 502
 503                 /*
 504                  * The following code is the optional support for the so-called
 505                  * "implicit return". Some AML code assumes that the last value of the
 506                  * method is "implicitly" returned to the caller, in the absence of an
 507                  * explicit return value.
 508                  *
 509                  * Just save the last result of the method as the return value.
 510                  *
 511                  * NOTE: this is optional because the ASL language does not actually
 512                  * support this behavior.
 513                  */
 514                 else if (!acpi_ds_do_implicit_return
 515                          (return_desc, walk_state, FALSE)
 516                          || same_as_implicit_return) {
 517                         /*
 518                          * Delete the return value if it will not be used by the
 519                          * calling method or remove one reference if the explicit return
 520                          * is the same as the implicit return value.
 521                          */
 522                         acpi_ut_remove_reference(return_desc);
 523                 }
 524         }
 525
 526         return_ACPI_STATUS(AE_OK);
 527 }
 528
 529 /*******************************************************************************
 530  *
 531  * FUNCTION:    acpi_ds_terminate_control_method
 532  *
 533  * PARAMETERS:  method_desc         - Method object
 534  *              walk_state          - State associated with the method
 535  *
 536  * RETURN:      None
 537  *
 538  * DESCRIPTION: Terminate a control method. Delete everything that the method
 539  *              created, delete all locals and arguments, and delete the parse
 540  *              tree if requested.
 541  *
 542  * MUTEX:       Interpreter is locked
 543  *
 544  ******************************************************************************/
 545
 546 void
 547 acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
 548                                  struct acpi_walk_state *walk_state)
 549 {
 550
 551         ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);
 552
 553         /* method_desc is required, walk_state is optional */
 554
 555         if (!method_desc) {
 556                 return_VOID;
 557         }
 558
 559         if (walk_state) {
 560
 561                 /* Delete all arguments and locals */
 562
 563                 acpi_ds_method_data_delete_all(walk_state);
 564
 565                 /*
 566                  * If method is serialized, release the mutex and restore the
 567                  * current sync level for this thread
 568                  */
 569                 if (method_desc->method.mutex) {
 570
 571                         /* Acquisition Depth handles recursive calls */
 572
 573                         method_desc->method.mutex->mutex.acquisition_depth--;
 574                         if (!method_desc->method.mutex->mutex.acquisition_depth) {
 575                                 walk_state->thread->current_sync_level =
 576                                     method_desc->method.mutex->mutex.
 577                                     original_sync_level;
 578
 579                                 acpi_os_release_mutex(method_desc->method.
 580                                                       mutex->mutex.os_mutex);
 581                                 method_desc->method.mutex->mutex.thread_id = 0;
 582                         }
 583                 }
 584
 585                 /*
 586                  * Delete any namespace objects created anywhere within the
 587                  * namespace by the execution of this method. Unless:
 588                  * 1) This method is a module-level executable code method, in which
 589                  *    case we want make the objects permanent.
 590                  * 2) There are other threads executing the method, in which case we
 591                  *    will wait until the last thread has completed.
 592                  */
 593                 if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)
 594                     && (method_desc->method.thread_count == 1)) {
 595
 596                         /* Delete any direct children of (created by) this method */
 597
 598                         acpi_ns_delete_namespace_subtree(walk_state->
 599                                                          method_node);
 600
 601                         /*
 602                          * Delete any objects that were created by this method
 603                          * elsewhere in the namespace (if any were created).
 604                          * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the
 605                          * deletion such that we don't have to perform an entire
 606                          * namespace walk for every control method execution.
 607                          */
 608                         if (method_desc->method.
 609                             info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {
 610                                 acpi_ns_delete_namespace_by_owner(method_desc->
 611                                                                   method.
 612                                                                   owner_id);
 613                                 method_desc->method.info_flags &=
 614                                     ~ACPI_METHOD_MODIFIED_NAMESPACE;
 615                         }
 616                 }
 617         }
 618
 619         /* Decrement the thread count on the method */
 620
 621         if (method_desc->method.thread_count) {
 622                 method_desc->method.thread_count--;
 623         } else {
 624                 ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));
 625         }
 626
 627         /* Are there any other threads currently executing this method? */
 628
 629         if (method_desc->method.thread_count) {
 630                 /*
 631                  * Additional threads. Do not release the owner_id in this case,
 632                  * we immediately reuse it for the next thread executing this method
 633                  */
 634                 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 635                                   "*** Completed execution of one thread, %u threads remaining\n",
 636                                   method_desc->method.thread_count));
 637         } else {
 638                 /* This is the only executing thread for this method */
 639
 640                 /*
 641                  * Support to dynamically change a method from not_serialized to
 642                  * Serialized if it appears that the method is incorrectly written and
 643                  * does not support multiple thread execution. The best example of this
 644                  * is if such a method creates namespace objects and blocks. A second
 645                  * thread will fail with an AE_ALREADY_EXISTS exception.
 646                  *
 647                  * This code is here because we must wait until the last thread exits
 648                  * before marking the method as serialized.
 649                  */
 650                 if (method_desc->method.
 651                     info_flags & ACPI_METHOD_SERIALIZED_PENDING) {
 652                         if (walk_state) {
 653                                 ACPI_INFO((AE_INFO,
 654                                            "Marking method %4.4s as Serialized because of AE_ALREADY_EXISTS error",
 655                                            walk_state->method_node->name.
 656                                            ascii));
 657                         }
 658
 659                         /*
 660                          * Method tried to create an object twice and was marked as
 661                          * "pending serialized". The probable cause is that the method
 662                          * cannot handle reentrancy.
 663                          *
 664                          * The method was created as not_serialized, but it tried to create
 665                          * a named object and then blocked, causing the second thread
 666                          * entrance to begin and then fail. Workaround this problem by
 667                          * marking the method permanently as Serialized when the last
 668                          * thread exits here.
 669                          */
 670                         method_desc->method.info_flags &=
 671                             ~ACPI_METHOD_SERIALIZED_PENDING;
 672                         method_desc->method.info_flags |=
 673                             ACPI_METHOD_SERIALIZED;
 674                         method_desc->method.sync_level = 0;
 675                 }
 676
 677                 /* No more threads, we can free the owner_id */
 678
 679                 if (!
 680                     (method_desc->method.
 681                      info_flags & ACPI_METHOD_MODULE_LEVEL)) {
 682                         acpi_ut_release_owner_id(&method_desc->method.owner_id);
 683                 }
 684         }
 685
 686         return_VOID;
 687 }