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 - 2015, 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 #include "acparser.h"
  53 #include "amlcode.h"
  54
  55 #define _COMPONENT          ACPI_DISPATCHER
  56 ACPI_MODULE_NAME("dsmethod")
  57
  58 /* Local prototypes */
  59 static acpi_status
  60 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
  61                              union acpi_parse_object **out_op);
  62
  63 static acpi_status
  64 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc);
  65
  66 /*******************************************************************************
  67  *
  68  * FUNCTION:    acpi_ds_auto_serialize_method
  69  *
  70  * PARAMETERS:  node                        - Namespace Node of the method
  71  *              obj_desc                    - Method object attached to node
  72  *
  73  * RETURN:      Status
  74  *
  75  * DESCRIPTION: Parse a control method AML to scan for control methods that
  76  *              need serialization due to the creation of named objects.
  77  *
  78  * NOTE: It is a bit of overkill to mark all such methods serialized, since
  79  * there is only a problem if the method actually blocks during execution.
  80  * A blocking operation is, for example, a Sleep() operation, or any access
  81  * to an operation region. However, it is probably not possible to easily
  82  * detect whether a method will block or not, so we simply mark all suspicious
  83  * methods as serialized.
  84  *
  85  * NOTE2: This code is essentially a generic routine for parsing a single
  86  * control method.
  87  *
  88  ******************************************************************************/
  89
  90 acpi_status
  91 acpi_ds_auto_serialize_method(struct acpi_namespace_node *node,
  92                               union acpi_operand_object *obj_desc)
  93 {
  94         acpi_status status;
  95         union acpi_parse_object *op = NULL;
  96         struct acpi_walk_state *walk_state;
  97
  98         ACPI_FUNCTION_TRACE_PTR(ds_auto_serialize_method, node);
  99
 100         ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
 101                           "Method auto-serialization parse [%4.4s] %p\n",
 102                           acpi_ut_get_node_name(node), node));
 103
 104         /* Create/Init a root op for the method parse tree */
 105
 106         op = acpi_ps_alloc_op(AML_METHOD_OP, obj_desc->method.aml_start);
 107         if (!op) {
 108                 return_ACPI_STATUS(AE_NO_MEMORY);
 109         }
 110
 111         acpi_ps_set_name(op, node->name.integer);
 112         op->common.node = node;
 113
 114         /* Create and initialize a new walk state */
 115
 116         walk_state =
 117             acpi_ds_create_walk_state(node->owner_id, NULL, NULL, NULL);
 118         if (!walk_state) {
 119                 acpi_ps_free_op(op);
 120                 return_ACPI_STATUS(AE_NO_MEMORY);
 121         }
 122
 123         status =
 124             acpi_ds_init_aml_walk(walk_state, op, node,
 125                                   obj_desc->method.aml_start,
 126                                   obj_desc->method.aml_length, NULL, 0);
 127         if (ACPI_FAILURE(status)) {
 128                 acpi_ds_delete_walk_state(walk_state);
 129                 acpi_ps_free_op(op);
 130                 return_ACPI_STATUS(status);
 131         }
 132
 133         walk_state->descending_callback = acpi_ds_detect_named_opcodes;
 134
 135         /* Parse the method, scan for creation of named objects */
 136
 137         status = acpi_ps_parse_aml(walk_state);
 138
 139         acpi_ps_delete_parse_tree(op);
 140         return_ACPI_STATUS(status);
 141 }
 142
 143 /*******************************************************************************
 144  *
 145  * FUNCTION:    acpi_ds_detect_named_opcodes
 146  *
 147  * PARAMETERS:  walk_state      - Current state of the parse tree walk
 148  *              out_op          - Unused, required for parser interface
 149  *
 150  * RETURN:      Status
 151  *
 152  * DESCRIPTION: Descending callback used during the loading of ACPI tables.
 153  *              Currently used to detect methods that must be marked serialized
 154  *              in order to avoid problems with the creation of named objects.
 155  *
 156  ******************************************************************************/
 157
 158 static acpi_status
 159 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
 160                              union acpi_parse_object **out_op)
 161 {
 162
 163         ACPI_FUNCTION_NAME(acpi_ds_detect_named_opcodes);
 164
 165         /* We are only interested in opcodes that create a new name */
 166
 167         if (!
 168             (walk_state->op_info->
 169              flags & (AML_NAMED | AML_CREATE | AML_FIELD))) {
 170                 return (AE_OK);
 171         }
 172
 173         /*
 174          * At this point, we know we have a Named object opcode.
 175          * Mark the method as serialized. Later code will create a mutex for
 176          * this method to enforce serialization.
 177          *
 178          * Note, ACPI_METHOD_IGNORE_SYNC_LEVEL flag means that we will ignore the
 179          * Sync Level mechanism for this method, even though it is now serialized.
 180          * Otherwise, there can be conflicts with existing ASL code that actually
 181          * uses sync levels.
 182          */
 183         walk_state->method_desc->method.sync_level = 0;
 184         walk_state->method_desc->method.info_flags |=
 185             (ACPI_METHOD_SERIALIZED | ACPI_METHOD_IGNORE_SYNC_LEVEL);
 186
 187         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 188                           "Method serialized [%4.4s] %p - [%s] (%4.4X)\n",
 189                           walk_state->method_node->name.ascii,
 190                           walk_state->method_node, walk_state->op_info->name,
 191                           walk_state->opcode));
 192
 193         /* Abort the parse, no need to examine this method any further */
 194
 195         return (AE_CTRL_TERMINATE);
 196 }
 197
 198 /*******************************************************************************
 199  *
 200  * FUNCTION:    acpi_ds_method_error
 201  *
 202  * PARAMETERS:  status          - Execution status
 203  *              walk_state      - Current state
 204  *
 205  * RETURN:      Status
 206  *
 207  * DESCRIPTION: Called on method error. Invoke the global exception handler if
 208  *              present, dump the method data if the disassembler is configured
 209  *
 210  *              Note: Allows the exception handler to change the status code
 211  *
 212  ******************************************************************************/
 213
 214 acpi_status
 215 acpi_ds_method_error(acpi_status status, struct acpi_walk_state * walk_state)
 216 {
 217         u32 aml_offset;
 218
 219         ACPI_FUNCTION_ENTRY();
 220
 221         /* Ignore AE_OK and control exception codes */
 222
 223         if (ACPI_SUCCESS(status) || (status & AE_CODE_CONTROL)) {
 224                 return (status);
 225         }
 226
 227         /* Invoke the global exception handler */
 228
 229         if (acpi_gbl_exception_handler) {
 230
 231                 /* Exit the interpreter, allow handler to execute methods */
 232
 233                 acpi_ex_exit_interpreter();
 234
 235                 /*
 236                  * Handler can map the exception code to anything it wants, including
 237                  * AE_OK, in which case the executing method will not be aborted.
 238                  */
 239                 aml_offset = (u32)ACPI_PTR_DIFF(walk_state->aml,
 240                                                 walk_state->parser_state.
 241                                                 aml_start);
 242
 243                 status = acpi_gbl_exception_handler(status,
 244                                                     walk_state->method_node ?
 245                                                     walk_state->method_node->
 246                                                     name.integer : 0,
 247                                                     walk_state->opcode,
 248                                                     aml_offset, NULL);
 249                 acpi_ex_enter_interpreter();
 250         }
 251
 252         acpi_ds_clear_implicit_return(walk_state);
 253
 254         if (ACPI_FAILURE(status)) {
 255                 acpi_ds_dump_method_stack(status, walk_state, walk_state->op);
 256
 257                 /* Display method locals/args if disassembler is present */
 258
 259 #ifdef ACPI_DISASSEMBLER
 260                 acpi_dm_dump_method_info(status, walk_state);
 261 #endif
 262         }
 263
 264         return (status);
 265 }
 266
 267 /*******************************************************************************
 268  *
 269  * FUNCTION:    acpi_ds_create_method_mutex
 270  *
 271  * PARAMETERS:  obj_desc            - The method object
 272  *
 273  * RETURN:      Status
 274  *
 275  * DESCRIPTION: Create a mutex object for a serialized control method
 276  *
 277  ******************************************************************************/
 278
 279 static acpi_status
 280 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc)
 281 {
 282         union acpi_operand_object *mutex_desc;
 283         acpi_status status;
 284
 285         ACPI_FUNCTION_TRACE(ds_create_method_mutex);
 286
 287         /* Create the new mutex object */
 288
 289         mutex_desc = acpi_ut_create_internal_object(ACPI_TYPE_MUTEX);
 290         if (!mutex_desc) {
 291                 return_ACPI_STATUS(AE_NO_MEMORY);
 292         }
 293
 294         /* Create the actual OS Mutex */
 295
 296         status = acpi_os_create_mutex(&mutex_desc->mutex.os_mutex);
 297         if (ACPI_FAILURE(status)) {
 298                 acpi_ut_delete_object_desc(mutex_desc);
 299                 return_ACPI_STATUS(status);
 300         }
 301
 302         mutex_desc->mutex.sync_level = method_desc->method.sync_level;
 303         method_desc->method.mutex = mutex_desc;
 304         return_ACPI_STATUS(AE_OK);
 305 }
 306
 307 /*******************************************************************************
 308  *
 309  * FUNCTION:    acpi_ds_begin_method_execution
 310  *
 311  * PARAMETERS:  method_node         - Node of the method
 312  *              obj_desc            - The method object
 313  *              walk_state          - current state, NULL if not yet executing
 314  *                                    a method.
 315  *
 316  * RETURN:      Status
 317  *
 318  * DESCRIPTION: Prepare a method for execution. Parses the method if necessary,
 319  *              increments the thread count, and waits at the method semaphore
 320  *              for clearance to execute.
 321  *
 322  ******************************************************************************/
 323
 324 acpi_status
 325 acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
 326                                union acpi_operand_object *obj_desc,
 327                                struct acpi_walk_state *walk_state)
 328 {
 329         acpi_status status = AE_OK;
 330
 331         ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);
 332
 333         if (!method_node) {
 334                 return_ACPI_STATUS(AE_NULL_ENTRY);
 335         }
 336
 337         acpi_ex_start_trace_method(method_node, obj_desc, walk_state);
 338
 339         /* Prevent wraparound of thread count */
 340
 341         if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {
 342                 ACPI_ERROR((AE_INFO,
 343                             "Method reached maximum reentrancy limit (255)"));
 344                 return_ACPI_STATUS(AE_AML_METHOD_LIMIT);
 345         }
 346
 347         /*
 348          * If this method is serialized, we need to acquire the method mutex.
 349          */
 350         if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {
 351                 /*
 352                  * Create a mutex for the method if it is defined to be Serialized
 353                  * and a mutex has not already been created. We defer the mutex creation
 354                  * until a method is actually executed, to minimize the object count
 355                  */
 356                 if (!obj_desc->method.mutex) {
 357                         status = acpi_ds_create_method_mutex(obj_desc);
 358                         if (ACPI_FAILURE(status)) {
 359                                 return_ACPI_STATUS(status);
 360                         }
 361                 }
 362
 363                 /*
 364                  * The current_sync_level (per-thread) must be less than or equal to
 365                  * the sync level of the method. This mechanism provides some
 366                  * deadlock prevention.
 367                  *
 368                  * If the method was auto-serialized, we just ignore the sync level
 369                  * mechanism, because auto-serialization of methods can interfere
 370                  * with ASL code that actually uses sync levels.
 371                  *
 372                  * Top-level method invocation has no walk state at this point
 373                  */
 374                 if (walk_state &&
 375                     (!(obj_desc->method.
 376                        info_flags & ACPI_METHOD_IGNORE_SYNC_LEVEL))
 377                     && (walk_state->thread->current_sync_level >
 378                         obj_desc->method.mutex->mutex.sync_level)) {
 379                         ACPI_ERROR((AE_INFO,
 380                                     "Cannot acquire Mutex for method [%4.4s], current SyncLevel is too large (%u)",
 381                                     acpi_ut_get_node_name(method_node),
 382                                     walk_state->thread->current_sync_level));
 383
 384                         return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
 385                 }
 386
 387                 /*
 388                  * Obtain the method mutex if necessary. Do not acquire mutex for a
 389                  * recursive call.
 390                  */
 391                 if (!walk_state ||
 392                     !obj_desc->method.mutex->mutex.thread_id ||
 393                     (walk_state->thread->thread_id !=
 394                      obj_desc->method.mutex->mutex.thread_id)) {
 395                         /*
 396                          * Acquire the method mutex. This releases the interpreter if we
 397                          * block (and reacquires it before it returns)
 398                          */
 399                         status =
 400                             acpi_ex_system_wait_mutex(obj_desc->method.mutex->
 401                                                       mutex.os_mutex,
 402                                                       ACPI_WAIT_FOREVER);
 403                         if (ACPI_FAILURE(status)) {
 404                                 return_ACPI_STATUS(status);
 405                         }
 406
 407                         /* Update the mutex and walk info and save the original sync_level */
 408
 409                         if (walk_state) {
 410                                 obj_desc->method.mutex->mutex.
 411                                     original_sync_level =
 412                                     walk_state->thread->current_sync_level;
 413
 414                                 obj_desc->method.mutex->mutex.thread_id =
 415                                     walk_state->thread->thread_id;
 416                                 walk_state->thread->current_sync_level =
 417                                     obj_desc->method.sync_level;
 418                         } else {
 419                                 obj_desc->method.mutex->mutex.
 420                                     original_sync_level =
 421                                     obj_desc->method.mutex->mutex.sync_level;
 422                         }
 423                 }
 424
 425                 /* Always increase acquisition depth */
 426
 427                 obj_desc->method.mutex->mutex.acquisition_depth++;
 428         }
 429
 430         /*
 431          * Allocate an Owner ID for this method, only if this is the first thread
 432          * to begin concurrent execution. We only need one owner_id, even if the
 433          * method is invoked recursively.
 434          */
 435         if (!obj_desc->method.owner_id) {
 436                 status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);
 437                 if (ACPI_FAILURE(status)) {
 438                         goto cleanup;
 439                 }
 440         }
 441
 442         /*
 443          * Increment the method parse tree thread count since it has been
 444          * reentered one more time (even if it is the same thread)
 445          */
 446         obj_desc->method.thread_count++;
 447         acpi_method_count++;
 448         return_ACPI_STATUS(status);
 449
 450 cleanup:
 451         /* On error, must release the method mutex (if present) */
 452
 453         if (obj_desc->method.mutex) {
 454                 acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);
 455         }
 456         return_ACPI_STATUS(status);
 457 }
 458
 459 /*******************************************************************************
 460  *
 461  * FUNCTION:    acpi_ds_call_control_method
 462  *
 463  * PARAMETERS:  thread              - Info for this thread
 464  *              this_walk_state     - Current walk state
 465  *              op                  - Current Op to be walked
 466  *
 467  * RETURN:      Status
 468  *
 469  * DESCRIPTION: Transfer execution to a called control method
 470  *
 471  ******************************************************************************/
 472
 473 acpi_status
 474 acpi_ds_call_control_method(struct acpi_thread_state *thread,
 475                             struct acpi_walk_state *this_walk_state,
 476                             union acpi_parse_object *op)
 477 {
 478         acpi_status status;
 479         struct acpi_namespace_node *method_node;
 480         struct acpi_walk_state *next_walk_state = NULL;
 481         union acpi_operand_object *obj_desc;
 482         struct acpi_evaluate_info *info;
 483         u32 i;
 484
 485         ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);
 486
 487         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 488                           "Calling method %p, currentstate=%p\n",
 489                           this_walk_state->prev_op, this_walk_state));
 490
 491         /*
 492          * Get the namespace entry for the control method we are about to call
 493          */
 494         method_node = this_walk_state->method_call_node;
 495         if (!method_node) {
 496                 return_ACPI_STATUS(AE_NULL_ENTRY);
 497         }
 498
 499         obj_desc = acpi_ns_get_attached_object(method_node);
 500         if (!obj_desc) {
 501                 return_ACPI_STATUS(AE_NULL_OBJECT);
 502         }
 503
 504         /* Init for new method, possibly wait on method mutex */
 505
 506         status = acpi_ds_begin_method_execution(method_node, obj_desc,
 507                                                 this_walk_state);
 508         if (ACPI_FAILURE(status)) {
 509                 return_ACPI_STATUS(status);
 510         }
 511
 512         /* Begin method parse/execution. Create a new walk state */
 513
 514         next_walk_state = acpi_ds_create_walk_state(obj_desc->method.owner_id,
 515                                                     NULL, obj_desc, thread);
 516         if (!next_walk_state) {
 517                 status = AE_NO_MEMORY;
 518                 goto cleanup;
 519         }
 520
 521         /*
 522          * The resolved arguments were put on the previous walk state's operand
 523          * stack. Operands on the previous walk state stack always
 524          * start at index 0. Also, null terminate the list of arguments
 525          */
 526         this_walk_state->operands[this_walk_state->num_operands] = NULL;
 527
 528         /*
 529          * Allocate and initialize the evaluation information block
 530          * TBD: this is somewhat inefficient, should change interface to
 531          * ds_init_aml_walk. For now, keeps this struct off the CPU stack
 532          */
 533         info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
 534         if (!info) {
 535                 status = AE_NO_MEMORY;
 536                 goto cleanup;
 537         }
 538
 539         info->parameters = &this_walk_state->operands[0];
 540
 541         status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,
 542                                        obj_desc->method.aml_start,
 543                                        obj_desc->method.aml_length, info,
 544                                        ACPI_IMODE_EXECUTE);
 545
 546         ACPI_FREE(info);
 547         if (ACPI_FAILURE(status)) {
 548                 goto cleanup;
 549         }
 550
 551         /*
 552          * Delete the operands on the previous walkstate operand stack
 553          * (they were copied to new objects)
 554          */
 555         for (i = 0; i < obj_desc->method.param_count; i++) {
 556                 acpi_ut_remove_reference(this_walk_state->operands[i]);
 557                 this_walk_state->operands[i] = NULL;
 558         }
 559
 560         /* Clear the operand stack */
 561
 562         this_walk_state->num_operands = 0;
 563
 564         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 565                           "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",
 566                           method_node->name.ascii, next_walk_state));
 567
 568         /* Invoke an internal method if necessary */
 569
 570         if (obj_desc->method.info_flags & ACPI_METHOD_INTERNAL_ONLY) {
 571                 status =
 572                     obj_desc->method.dispatch.implementation(next_walk_state);
 573                 if (status == AE_OK) {
 574                         status = AE_CTRL_TERMINATE;
 575                 }
 576         }
 577
 578         return_ACPI_STATUS(status);
 579
 580 cleanup:
 581
 582         /* On error, we must terminate the method properly */
 583
 584         acpi_ds_terminate_control_method(obj_desc, next_walk_state);
 585         acpi_ds_delete_walk_state(next_walk_state);
 586
 587         return_ACPI_STATUS(status);
 588 }
 589
 590 /*******************************************************************************
 591  *
 592  * FUNCTION:    acpi_ds_restart_control_method
 593  *
 594  * PARAMETERS:  walk_state          - State for preempted method (caller)
 595  *              return_desc         - Return value from the called method
 596  *
 597  * RETURN:      Status
 598  *
 599  * DESCRIPTION: Restart a method that was preempted by another (nested) method
 600  *              invocation. Handle the return value (if any) from the callee.
 601  *
 602  ******************************************************************************/
 603
 604 acpi_status
 605 acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,
 606                                union acpi_operand_object *return_desc)
 607 {
 608         acpi_status status;
 609         int same_as_implicit_return;
 610
 611         ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);
 612
 613         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 614                           "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",
 615                           acpi_ut_get_node_name(walk_state->method_node),
 616                           walk_state->method_call_op, return_desc));
 617
 618         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 619                           "    ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",
 620                           walk_state->return_used,
 621                           walk_state->results, walk_state));
 622
 623         /* Did the called method return a value? */
 624
 625         if (return_desc) {
 626
 627                 /* Is the implicit return object the same as the return desc? */
 628
 629                 same_as_implicit_return =
 630                     (walk_state->implicit_return_obj == return_desc);
 631
 632                 /* Are we actually going to use the return value? */
 633
 634                 if (walk_state->return_used) {
 635
 636                         /* Save the return value from the previous method */
 637
 638                         status = acpi_ds_result_push(return_desc, walk_state);
 639                         if (ACPI_FAILURE(status)) {
 640                                 acpi_ut_remove_reference(return_desc);
 641                                 return_ACPI_STATUS(status);
 642                         }
 643
 644                         /*
 645                          * Save as THIS method's return value in case it is returned
 646                          * immediately to yet another method
 647                          */
 648                         walk_state->return_desc = return_desc;
 649                 }
 650
 651                 /*
 652                  * The following code is the optional support for the so-called
 653                  * "implicit return". Some AML code assumes that the last value of the
 654                  * method is "implicitly" returned to the caller, in the absence of an
 655                  * explicit return value.
 656                  *
 657                  * Just save the last result of the method as the return value.
 658                  *
 659                  * NOTE: this is optional because the ASL language does not actually
 660                  * support this behavior.
 661                  */
 662                 else if (!acpi_ds_do_implicit_return
 663                          (return_desc, walk_state, FALSE)
 664                          || same_as_implicit_return) {
 665                         /*
 666                          * Delete the return value if it will not be used by the
 667                          * calling method or remove one reference if the explicit return
 668                          * is the same as the implicit return value.
 669                          */
 670                         acpi_ut_remove_reference(return_desc);
 671                 }
 672         }
 673
 674         return_ACPI_STATUS(AE_OK);
 675 }
 676
 677 /*******************************************************************************
 678  *
 679  * FUNCTION:    acpi_ds_terminate_control_method
 680  *
 681  * PARAMETERS:  method_desc         - Method object
 682  *              walk_state          - State associated with the method
 683  *
 684  * RETURN:      None
 685  *
 686  * DESCRIPTION: Terminate a control method. Delete everything that the method
 687  *              created, delete all locals and arguments, and delete the parse
 688  *              tree if requested.
 689  *
 690  * MUTEX:       Interpreter is locked
 691  *
 692  ******************************************************************************/
 693
 694 void
 695 acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
 696                                  struct acpi_walk_state *walk_state)
 697 {
 698
 699         ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);
 700
 701         /* method_desc is required, walk_state is optional */
 702
 703         if (!method_desc) {
 704                 return_VOID;
 705         }
 706
 707         if (walk_state) {
 708
 709                 /* Delete all arguments and locals */
 710
 711                 acpi_ds_method_data_delete_all(walk_state);
 712
 713                 /*
 714                  * If method is serialized, release the mutex and restore the
 715                  * current sync level for this thread
 716                  */
 717                 if (method_desc->method.mutex) {
 718
 719                         /* Acquisition Depth handles recursive calls */
 720
 721                         method_desc->method.mutex->mutex.acquisition_depth--;
 722                         if (!method_desc->method.mutex->mutex.acquisition_depth) {
 723                                 walk_state->thread->current_sync_level =
 724                                     method_desc->method.mutex->mutex.
 725                                     original_sync_level;
 726
 727                                 acpi_os_release_mutex(method_desc->method.
 728                                                       mutex->mutex.os_mutex);
 729                                 method_desc->method.mutex->mutex.thread_id = 0;
 730                         }
 731                 }
 732
 733                 /*
 734                  * Delete any namespace objects created anywhere within the
 735                  * namespace by the execution of this method. Unless:
 736                  * 1) This method is a module-level executable code method, in which
 737                  *    case we want make the objects permanent.
 738                  * 2) There are other threads executing the method, in which case we
 739                  *    will wait until the last thread has completed.
 740                  */
 741                 if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)
 742                     && (method_desc->method.thread_count == 1)) {
 743
 744                         /* Delete any direct children of (created by) this method */
 745
 746                         acpi_ns_delete_namespace_subtree(walk_state->
 747                                                          method_node);
 748
 749                         /*
 750                          * Delete any objects that were created by this method
 751                          * elsewhere in the namespace (if any were created).
 752                          * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the
 753                          * deletion such that we don't have to perform an entire
 754                          * namespace walk for every control method execution.
 755                          */
 756                         if (method_desc->method.
 757                             info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {
 758                                 acpi_ns_delete_namespace_by_owner(method_desc->
 759                                                                   method.
 760                                                                   owner_id);
 761                                 method_desc->method.info_flags &=
 762                                     ~ACPI_METHOD_MODIFIED_NAMESPACE;
 763                         }
 764                 }
 765         }
 766
 767         /* Decrement the thread count on the method */
 768
 769         if (method_desc->method.thread_count) {
 770                 method_desc->method.thread_count--;
 771         } else {
 772                 ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));
 773         }
 774
 775         /* Are there any other threads currently executing this method? */
 776
 777         if (method_desc->method.thread_count) {
 778                 /*
 779                  * Additional threads. Do not release the owner_id in this case,
 780                  * we immediately reuse it for the next thread executing this method
 781                  */
 782                 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 783                                   "*** Completed execution of one thread, %u threads remaining\n",
 784                                   method_desc->method.thread_count));
 785         } else {
 786                 /* This is the only executing thread for this method */
 787
 788                 /*
 789                  * Support to dynamically change a method from not_serialized to
 790                  * Serialized if it appears that the method is incorrectly written and
 791                  * does not support multiple thread execution. The best example of this
 792                  * is if such a method creates namespace objects and blocks. A second
 793                  * thread will fail with an AE_ALREADY_EXISTS exception.
 794                  *
 795                  * This code is here because we must wait until the last thread exits
 796                  * before marking the method as serialized.
 797                  */
 798                 if (method_desc->method.
 799                     info_flags & ACPI_METHOD_SERIALIZED_PENDING) {
 800                         if (walk_state) {
 801                                 ACPI_INFO((AE_INFO,
 802                                            "Marking method %4.4s as Serialized because of AE_ALREADY_EXISTS error",
 803                                            walk_state->method_node->name.
 804                                            ascii));
 805                         }
 806
 807                         /*
 808                          * Method tried to create an object twice and was marked as
 809                          * "pending serialized". The probable cause is that the method
 810                          * cannot handle reentrancy.
 811                          *
 812                          * The method was created as not_serialized, but it tried to create
 813                          * a named object and then blocked, causing the second thread
 814                          * entrance to begin and then fail. Workaround this problem by
 815                          * marking the method permanently as Serialized when the last
 816                          * thread exits here.
 817                          */
 818                         method_desc->method.info_flags &=
 819                             ~ACPI_METHOD_SERIALIZED_PENDING;
 820                         method_desc->method.info_flags |=
 821                             (ACPI_METHOD_SERIALIZED |
 822                              ACPI_METHOD_IGNORE_SYNC_LEVEL);
 823                         method_desc->method.sync_level = 0;
 824                 }
 825
 826                 /* No more threads, we can free the owner_id */
 827
 828                 if (!
 829                     (method_desc->method.
 830                      info_flags & ACPI_METHOD_MODULE_LEVEL)) {
 831                         acpi_ut_release_owner_id(&method_desc->method.owner_id);
 832                 }
 833         }
 834
 835         acpi_ex_stop_trace_method((struct acpi_namespace_node *)method_desc->
 836                                   method.node, method_desc, walk_state);
 837
 838         return_VOID;
 839 }