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 - 2011, 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 <acpi/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                 return_ACPI_STATUS(status);
 155         }
 156
 157         mutex_desc->mutex.sync_level = method_desc->method.sync_level;
 158         method_desc->method.mutex = mutex_desc;
 159         return_ACPI_STATUS(AE_OK);
 160 }
 161
 162 /*******************************************************************************
 163  *
 164  * FUNCTION:    acpi_ds_begin_method_execution
 165  *
 166  * PARAMETERS:  method_node         - Node of the method
 167  *              obj_desc            - The method object
 168  *              walk_state          - current state, NULL if not yet executing
 169  *                                    a method.
 170  *
 171  * RETURN:      Status
 172  *
 173  * DESCRIPTION: Prepare a method for execution.  Parses the method if necessary,
 174  *              increments the thread count, and waits at the method semaphore
 175  *              for clearance to execute.
 176  *
 177  ******************************************************************************/
 178
 179 acpi_status
 180 acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
 181                                union acpi_operand_object *obj_desc,
 182                                struct acpi_walk_state *walk_state)
 183 {
 184         acpi_status status = AE_OK;
 185
 186         ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);
 187
 188         if (!method_node) {
 189                 return_ACPI_STATUS(AE_NULL_ENTRY);
 190         }
 191
 192         /* Prevent wraparound of thread count */
 193
 194         if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {
 195                 ACPI_ERROR((AE_INFO,
 196                             "Method reached maximum reentrancy limit (255)"));
 197                 return_ACPI_STATUS(AE_AML_METHOD_LIMIT);
 198         }
 199
 200         /*
 201          * If this method is serialized, we need to acquire the method mutex.
 202          */
 203         if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {
 204                 /*
 205                  * Create a mutex for the method if it is defined to be Serialized
 206                  * and a mutex has not already been created. We defer the mutex creation
 207                  * until a method is actually executed, to minimize the object count
 208                  */
 209                 if (!obj_desc->method.mutex) {
 210                         status = acpi_ds_create_method_mutex(obj_desc);
 211                         if (ACPI_FAILURE(status)) {
 212                                 return_ACPI_STATUS(status);
 213                         }
 214                 }
 215
 216                 /*
 217                  * The current_sync_level (per-thread) must be less than or equal to
 218                  * the sync level of the method. This mechanism provides some
 219                  * deadlock prevention
 220                  *
 221                  * Top-level method invocation has no walk state at this point
 222                  */
 223                 if (walk_state &&
 224                     (walk_state->thread->current_sync_level >
 225                      obj_desc->method.mutex->mutex.sync_level)) {
 226                         ACPI_ERROR((AE_INFO,
 227                                     "Cannot acquire Mutex for method [%4.4s], current SyncLevel is too large (%u)",
 228                                     acpi_ut_get_node_name(method_node),
 229                                     walk_state->thread->current_sync_level));
 230
 231                         return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
 232                 }
 233
 234                 /*
 235                  * Obtain the method mutex if necessary. Do not acquire mutex for a
 236                  * recursive call.
 237                  */
 238                 if (!walk_state ||
 239                     !obj_desc->method.mutex->mutex.thread_id ||
 240                     (walk_state->thread->thread_id !=
 241                      obj_desc->method.mutex->mutex.thread_id)) {
 242                         /*
 243                          * Acquire the method mutex. This releases the interpreter if we
 244                          * block (and reacquires it before it returns)
 245                          */
 246                         status =
 247                             acpi_ex_system_wait_mutex(obj_desc->method.mutex->
 248                                                       mutex.os_mutex,
 249                                                       ACPI_WAIT_FOREVER);
 250                         if (ACPI_FAILURE(status)) {
 251                                 return_ACPI_STATUS(status);
 252                         }
 253
 254                         /* Update the mutex and walk info and save the original sync_level */
 255
 256                         if (walk_state) {
 257                                 obj_desc->method.mutex->mutex.
 258                                     original_sync_level =
 259                                     walk_state->thread->current_sync_level;
 260
 261                                 obj_desc->method.mutex->mutex.thread_id =
 262                                     walk_state->thread->thread_id;
 263                                 walk_state->thread->current_sync_level =
 264                                     obj_desc->method.sync_level;
 265                         } else {
 266                                 obj_desc->method.mutex->mutex.
 267                                     original_sync_level =
 268                                     obj_desc->method.mutex->mutex.sync_level;
 269
 270                                 obj_desc->method.mutex->mutex.thread_id =
 271                                     acpi_os_get_thread_id();
 272                         }
 273                 }
 274
 275                 /* Always increase acquisition depth */
 276
 277                 obj_desc->method.mutex->mutex.acquisition_depth++;
 278         }
 279
 280         /*
 281          * Allocate an Owner ID for this method, only if this is the first thread
 282          * to begin concurrent execution. We only need one owner_id, even if the
 283          * method is invoked recursively.
 284          */
 285         if (!obj_desc->method.owner_id) {
 286                 status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);
 287                 if (ACPI_FAILURE(status)) {
 288                         goto cleanup;
 289                 }
 290         }
 291
 292         /*
 293          * Increment the method parse tree thread count since it has been
 294          * reentered one more time (even if it is the same thread)
 295          */
 296         obj_desc->method.thread_count++;
 297         return_ACPI_STATUS(status);
 298
 299       cleanup:
 300         /* On error, must release the method mutex (if present) */
 301
 302         if (obj_desc->method.mutex) {
 303                 acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);
 304         }
 305         return_ACPI_STATUS(status);
 306 }
 307
 308 /*******************************************************************************
 309  *
 310  * FUNCTION:    acpi_ds_call_control_method
 311  *
 312  * PARAMETERS:  Thread              - Info for this thread
 313  *              this_walk_state     - Current walk state
 314  *              Op                  - Current Op to be walked
 315  *
 316  * RETURN:      Status
 317  *
 318  * DESCRIPTION: Transfer execution to a called control method
 319  *
 320  ******************************************************************************/
 321
 322 acpi_status
 323 acpi_ds_call_control_method(struct acpi_thread_state *thread,
 324                             struct acpi_walk_state *this_walk_state,
 325                             union acpi_parse_object *op)
 326 {
 327         acpi_status status;
 328         struct acpi_namespace_node *method_node;
 329         struct acpi_walk_state *next_walk_state = NULL;
 330         union acpi_operand_object *obj_desc;
 331         struct acpi_evaluate_info *info;
 332         u32 i;
 333
 334         ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);
 335
 336         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 337                           "Calling method %p, currentstate=%p\n",
 338                           this_walk_state->prev_op, this_walk_state));
 339
 340         /*
 341          * Get the namespace entry for the control method we are about to call
 342          */
 343         method_node = this_walk_state->method_call_node;
 344         if (!method_node) {
 345                 return_ACPI_STATUS(AE_NULL_ENTRY);
 346         }
 347
 348         obj_desc = acpi_ns_get_attached_object(method_node);
 349         if (!obj_desc) {
 350                 return_ACPI_STATUS(AE_NULL_OBJECT);
 351         }
 352
 353         /* Init for new method, possibly wait on method mutex */
 354
 355         status = acpi_ds_begin_method_execution(method_node, obj_desc,
 356                                                 this_walk_state);
 357         if (ACPI_FAILURE(status)) {
 358                 return_ACPI_STATUS(status);
 359         }
 360
 361         /* Begin method parse/execution. Create a new walk state */
 362
 363         next_walk_state = acpi_ds_create_walk_state(obj_desc->method.owner_id,
 364                                                     NULL, obj_desc, thread);
 365         if (!next_walk_state) {
 366                 status = AE_NO_MEMORY;
 367                 goto cleanup;
 368         }
 369
 370         /*
 371          * The resolved arguments were put on the previous walk state's operand
 372          * stack. Operands on the previous walk state stack always
 373          * start at index 0. Also, null terminate the list of arguments
 374          */
 375         this_walk_state->operands[this_walk_state->num_operands] = NULL;
 376
 377         /*
 378          * Allocate and initialize the evaluation information block
 379          * TBD: this is somewhat inefficient, should change interface to
 380          * ds_init_aml_walk. For now, keeps this struct off the CPU stack
 381          */
 382         info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
 383         if (!info) {
 384                 return_ACPI_STATUS(AE_NO_MEMORY);
 385         }
 386
 387         info->parameters = &this_walk_state->operands[0];
 388
 389         status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,
 390                                        obj_desc->method.aml_start,
 391                                        obj_desc->method.aml_length, info,
 392                                        ACPI_IMODE_EXECUTE);
 393
 394         ACPI_FREE(info);
 395         if (ACPI_FAILURE(status)) {
 396                 goto cleanup;
 397         }
 398
 399         /*
 400          * Delete the operands on the previous walkstate operand stack
 401          * (they were copied to new objects)
 402          */
 403         for (i = 0; i < obj_desc->method.param_count; i++) {
 404                 acpi_ut_remove_reference(this_walk_state->operands[i]);
 405                 this_walk_state->operands[i] = NULL;
 406         }
 407
 408         /* Clear the operand stack */
 409
 410         this_walk_state->num_operands = 0;
 411
 412         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 413                           "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",
 414                           method_node->name.ascii, next_walk_state));
 415
 416         /* Invoke an internal method if necessary */
 417
 418         if (obj_desc->method.info_flags & ACPI_METHOD_INTERNAL_ONLY) {
 419                 status =
 420                     obj_desc->method.dispatch.implementation(next_walk_state);
 421                 if (status == AE_OK) {
 422                         status = AE_CTRL_TERMINATE;
 423                 }
 424         }
 425
 426         return_ACPI_STATUS(status);
 427
 428       cleanup:
 429
 430         /* On error, we must terminate the method properly */
 431
 432         acpi_ds_terminate_control_method(obj_desc, next_walk_state);
 433         if (next_walk_state) {
 434                 acpi_ds_delete_walk_state(next_walk_state);
 435         }
 436
 437         return_ACPI_STATUS(status);
 438 }
 439
 440 /*******************************************************************************
 441  *
 442  * FUNCTION:    acpi_ds_restart_control_method
 443  *
 444  * PARAMETERS:  walk_state          - State for preempted method (caller)
 445  *              return_desc         - Return value from the called method
 446  *
 447  * RETURN:      Status
 448  *
 449  * DESCRIPTION: Restart a method that was preempted by another (nested) method
 450  *              invocation.  Handle the return value (if any) from the callee.
 451  *
 452  ******************************************************************************/
 453
 454 acpi_status
 455 acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,
 456                                union acpi_operand_object *return_desc)
 457 {
 458         acpi_status status;
 459         int same_as_implicit_return;
 460
 461         ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);
 462
 463         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 464                           "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",
 465                           acpi_ut_get_node_name(walk_state->method_node),
 466                           walk_state->method_call_op, return_desc));
 467
 468         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 469                           "    ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",
 470                           walk_state->return_used,
 471                           walk_state->results, walk_state));
 472
 473         /* Did the called method return a value? */
 474
 475         if (return_desc) {
 476
 477                 /* Is the implicit return object the same as the return desc? */
 478
 479                 same_as_implicit_return =
 480                     (walk_state->implicit_return_obj == return_desc);
 481
 482                 /* Are we actually going to use the return value? */
 483
 484                 if (walk_state->return_used) {
 485
 486                         /* Save the return value from the previous method */
 487
 488                         status = acpi_ds_result_push(return_desc, walk_state);
 489                         if (ACPI_FAILURE(status)) {
 490                                 acpi_ut_remove_reference(return_desc);
 491                                 return_ACPI_STATUS(status);
 492                         }
 493
 494                         /*
 495                          * Save as THIS method's return value in case it is returned
 496                          * immediately to yet another method
 497                          */
 498                         walk_state->return_desc = return_desc;
 499                 }
 500
 501                 /*
 502                  * The following code is the optional support for the so-called
 503                  * "implicit return". Some AML code assumes that the last value of the
 504                  * method is "implicitly" returned to the caller, in the absence of an
 505                  * explicit return value.
 506                  *
 507                  * Just save the last result of the method as the return value.
 508                  *
 509                  * NOTE: this is optional because the ASL language does not actually
 510                  * support this behavior.
 511                  */
 512                 else if (!acpi_ds_do_implicit_return
 513                          (return_desc, walk_state, FALSE)
 514                          || same_as_implicit_return) {
 515                         /*
 516                          * Delete the return value if it will not be used by the
 517                          * calling method or remove one reference if the explicit return
 518                          * is the same as the implicit return value.
 519                          */
 520                         acpi_ut_remove_reference(return_desc);
 521                 }
 522         }
 523
 524         return_ACPI_STATUS(AE_OK);
 525 }
 526
 527 /*******************************************************************************
 528  *
 529  * FUNCTION:    acpi_ds_terminate_control_method
 530  *
 531  * PARAMETERS:  method_desc         - Method object
 532  *              walk_state          - State associated with the method
 533  *
 534  * RETURN:      None
 535  *
 536  * DESCRIPTION: Terminate a control method.  Delete everything that the method
 537  *              created, delete all locals and arguments, and delete the parse
 538  *              tree if requested.
 539  *
 540  * MUTEX:       Interpreter is locked
 541  *
 542  ******************************************************************************/
 543
 544 void
 545 acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
 546                                  struct acpi_walk_state *walk_state)
 547 {
 548
 549         ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);
 550
 551         /* method_desc is required, walk_state is optional */
 552
 553         if (!method_desc) {
 554                 return_VOID;
 555         }
 556
 557         if (walk_state) {
 558
 559                 /* Delete all arguments and locals */
 560
 561                 acpi_ds_method_data_delete_all(walk_state);
 562
 563                 /*
 564                  * If method is serialized, release the mutex and restore the
 565                  * current sync level for this thread
 566                  */
 567                 if (method_desc->method.mutex) {
 568
 569                         /* Acquisition Depth handles recursive calls */
 570
 571                         method_desc->method.mutex->mutex.acquisition_depth--;
 572                         if (!method_desc->method.mutex->mutex.acquisition_depth) {
 573                                 walk_state->thread->current_sync_level =
 574                                     method_desc->method.mutex->mutex.
 575                                     original_sync_level;
 576
 577                                 acpi_os_release_mutex(method_desc->method.
 578                                                       mutex->mutex.os_mutex);
 579                                 method_desc->method.mutex->mutex.thread_id = 0;
 580                         }
 581                 }
 582
 583                 /*
 584                  * Delete any namespace objects created anywhere within the
 585                  * namespace by the execution of this method. Unless:
 586                  * 1) This method is a module-level executable code method, in which
 587                  *    case we want make the objects permanent.
 588                  * 2) There are other threads executing the method, in which case we
 589                  *    will wait until the last thread has completed.
 590                  */
 591                 if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)
 592                     && (method_desc->method.thread_count == 1)) {
 593
 594                         /* Delete any direct children of (created by) this method */
 595
 596                         acpi_ns_delete_namespace_subtree(walk_state->
 597                                                          method_node);
 598
 599                         /*
 600                          * Delete any objects that were created by this method
 601                          * elsewhere in the namespace (if any were created).
 602                          * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the
 603                          * deletion such that we don't have to perform an entire
 604                          * namespace walk for every control method execution.
 605                          */
 606                         if (method_desc->method.
 607                             info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {
 608                                 acpi_ns_delete_namespace_by_owner(method_desc->
 609                                                                   method.
 610                                                                   owner_id);
 611                                 method_desc->method.info_flags &=
 612                                     ~ACPI_METHOD_MODIFIED_NAMESPACE;
 613                         }
 614                 }
 615         }
 616
 617         /* Decrement the thread count on the method */
 618
 619         if (method_desc->method.thread_count) {
 620                 method_desc->method.thread_count--;
 621         } else {
 622                 ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));
 623         }
 624
 625         /* Are there any other threads currently executing this method? */
 626
 627         if (method_desc->method.thread_count) {
 628                 /*
 629                  * Additional threads. Do not release the owner_id in this case,
 630                  * we immediately reuse it for the next thread executing this method
 631                  */
 632                 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 633                                   "*** Completed execution of one thread, %u threads remaining\n",
 634                                   method_desc->method.thread_count));
 635         } else {
 636                 /* This is the only executing thread for this method */
 637
 638                 /*
 639                  * Support to dynamically change a method from not_serialized to
 640                  * Serialized if it appears that the method is incorrectly written and
 641                  * does not support multiple thread execution. The best example of this
 642                  * is if such a method creates namespace objects and blocks. A second
 643                  * thread will fail with an AE_ALREADY_EXISTS exception.
 644                  *
 645                  * This code is here because we must wait until the last thread exits
 646                  * before marking the method as serialized.
 647                  */
 648                 if (method_desc->method.
 649                     info_flags & ACPI_METHOD_SERIALIZED_PENDING) {
 650                         if (walk_state) {
 651                                 ACPI_INFO((AE_INFO,
 652                                            "Marking method %4.4s as Serialized because of AE_ALREADY_EXISTS error",
 653                                            walk_state->method_node->name.
 654                                            ascii));
 655                         }
 656
 657                         /*
 658                          * Method tried to create an object twice and was marked as
 659                          * "pending serialized". The probable cause is that the method
 660                          * cannot handle reentrancy.
 661                          *
 662                          * The method was created as not_serialized, but it tried to create
 663                          * a named object and then blocked, causing the second thread
 664                          * entrance to begin and then fail. Workaround this problem by
 665                          * marking the method permanently as Serialized when the last
 666                          * thread exits here.
 667                          */
 668                         method_desc->method.info_flags &=
 669                             ~ACPI_METHOD_SERIALIZED_PENDING;
 670                         method_desc->method.info_flags |=
 671                             ACPI_METHOD_SERIALIZED;
 672                         method_desc->method.sync_level = 0;
 673                 }
 674
 675                 /* No more threads, we can free the owner_id */
 676
 677                 if (!
 678                     (method_desc->method.
 679                      info_flags & ACPI_METHOD_MODULE_LEVEL)) {
 680                         acpi_ut_release_owner_id(&method_desc->method.owner_id);
 681                 }
 682         }
 683
 684         return_VOID;
 685 }