drivers/acpi/acpica/dsmethod.c

   1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
   2 /******************************************************************************
   3  *
   4  * Module Name: dsmethod - Parser/Interpreter interface - control method parsing
   5  *
   6  * Copyright (C) 2000 - 2023, Intel Corp.
   7  *
   8  *****************************************************************************/
   9
  10 #include <acpi/acpi.h>
  11 #include "accommon.h"
  12 #include "acdispat.h"
  13 #include "acinterp.h"
  14 #include "acnamesp.h"
  15 #include "acparser.h"
  16 #include "amlcode.h"
  17 #include "acdebug.h"
  18
  19 #define _COMPONENT          ACPI_DISPATCHER
  20 ACPI_MODULE_NAME("dsmethod")
  21
  22 /* Local prototypes */
  23 static acpi_status
  24 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
  25                              union acpi_parse_object **out_op);
  26
  27 static acpi_status
  28 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc);
  29
  30 /*******************************************************************************
  31  *
  32  * FUNCTION:    acpi_ds_auto_serialize_method
  33  *
  34  * PARAMETERS:  node                        - Namespace Node of the method
  35  *              obj_desc                    - Method object attached to node
  36  *
  37  * RETURN:      Status
  38  *
  39  * DESCRIPTION: Parse a control method AML to scan for control methods that
  40  *              need serialization due to the creation of named objects.
  41  *
  42  * NOTE: It is a bit of overkill to mark all such methods serialized, since
  43  * there is only a problem if the method actually blocks during execution.
  44  * A blocking operation is, for example, a Sleep() operation, or any access
  45  * to an operation region. However, it is probably not possible to easily
  46  * detect whether a method will block or not, so we simply mark all suspicious
  47  * methods as serialized.
  48  *
  49  * NOTE2: This code is essentially a generic routine for parsing a single
  50  * control method.
  51  *
  52  ******************************************************************************/
  53
  54 acpi_status
  55 acpi_ds_auto_serialize_method(struct acpi_namespace_node *node,
  56                               union acpi_operand_object *obj_desc)
  57 {
  58         acpi_status status;
  59         union acpi_parse_object *op = NULL;
  60         struct acpi_walk_state *walk_state;
  61
  62         ACPI_FUNCTION_TRACE_PTR(ds_auto_serialize_method, node);
  63
  64         ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
  65                           "Method auto-serialization parse [%4.4s] %p\n",
  66                           acpi_ut_get_node_name(node), node));
  67
  68         /* Create/Init a root op for the method parse tree */
  69
  70         op = acpi_ps_alloc_op(AML_METHOD_OP, obj_desc->method.aml_start);
  71         if (!op) {
  72                 return_ACPI_STATUS(AE_NO_MEMORY);
  73         }
  74
  75         acpi_ps_set_name(op, node->name.integer);
  76         op->common.node = node;
  77
  78         /* Create and initialize a new walk state */
  79
  80         walk_state =
  81             acpi_ds_create_walk_state(node->owner_id, NULL, NULL, NULL);
  82         if (!walk_state) {
  83                 acpi_ps_free_op(op);
  84                 return_ACPI_STATUS(AE_NO_MEMORY);
  85         }
  86
  87         status = acpi_ds_init_aml_walk(walk_state, op, node,
  88                                        obj_desc->method.aml_start,
  89                                        obj_desc->method.aml_length, NULL, 0);
  90         if (ACPI_FAILURE(status)) {
  91                 acpi_ds_delete_walk_state(walk_state);
  92                 acpi_ps_free_op(op);
  93                 return_ACPI_STATUS(status);
  94         }
  95
  96         walk_state->descending_callback = acpi_ds_detect_named_opcodes;
  97
  98         /* Parse the method, scan for creation of named objects */
  99
 100         status = acpi_ps_parse_aml(walk_state);
 101
 102         acpi_ps_delete_parse_tree(op);
 103         return_ACPI_STATUS(status);
 104 }
 105
 106 /*******************************************************************************
 107  *
 108  * FUNCTION:    acpi_ds_detect_named_opcodes
 109  *
 110  * PARAMETERS:  walk_state      - Current state of the parse tree walk
 111  *              out_op          - Unused, required for parser interface
 112  *
 113  * RETURN:      Status
 114  *
 115  * DESCRIPTION: Descending callback used during the loading of ACPI tables.
 116  *              Currently used to detect methods that must be marked serialized
 117  *              in order to avoid problems with the creation of named objects.
 118  *
 119  ******************************************************************************/
 120
 121 static acpi_status
 122 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
 123                              union acpi_parse_object **out_op)
 124 {
 125
 126         ACPI_FUNCTION_NAME(acpi_ds_detect_named_opcodes);
 127
 128         /* We are only interested in opcodes that create a new name */
 129
 130         if (!
 131             (walk_state->op_info->
 132              flags & (AML_NAMED | AML_CREATE | AML_FIELD))) {
 133                 return (AE_OK);
 134         }
 135
 136         /*
 137          * At this point, we know we have a Named object opcode.
 138          * Mark the method as serialized. Later code will create a mutex for
 139          * this method to enforce serialization.
 140          *
 141          * Note, ACPI_METHOD_IGNORE_SYNC_LEVEL flag means that we will ignore the
 142          * Sync Level mechanism for this method, even though it is now serialized.
 143          * Otherwise, there can be conflicts with existing ASL code that actually
 144          * uses sync levels.
 145          */
 146         walk_state->method_desc->method.sync_level = 0;
 147         walk_state->method_desc->method.info_flags |=
 148             (ACPI_METHOD_SERIALIZED | ACPI_METHOD_IGNORE_SYNC_LEVEL);
 149
 150         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 151                           "Method serialized [%4.4s] %p - [%s] (%4.4X)\n",
 152                           walk_state->method_node->name.ascii,
 153                           walk_state->method_node, walk_state->op_info->name,
 154                           walk_state->opcode));
 155
 156         /* Abort the parse, no need to examine this method any further */
 157
 158         return (AE_CTRL_TERMINATE);
 159 }
 160
 161 /*******************************************************************************
 162  *
 163  * FUNCTION:    acpi_ds_method_error
 164  *
 165  * PARAMETERS:  status          - Execution status
 166  *              walk_state      - Current state
 167  *
 168  * RETURN:      Status
 169  *
 170  * DESCRIPTION: Called on method error. Invoke the global exception handler if
 171  *              present, dump the method data if the debugger is configured
 172  *
 173  *              Note: Allows the exception handler to change the status code
 174  *
 175  ******************************************************************************/
 176
 177 acpi_status
 178 acpi_ds_method_error(acpi_status status, struct acpi_walk_state *walk_state)
 179 {
 180         u32 aml_offset;
 181         acpi_name name = 0;
 182
 183         ACPI_FUNCTION_ENTRY();
 184
 185         /* Ignore AE_OK and control exception codes */
 186
 187         if (ACPI_SUCCESS(status) || (status & AE_CODE_CONTROL)) {
 188                 return (status);
 189         }
 190
 191         /* Invoke the global exception handler */
 192
 193         if (acpi_gbl_exception_handler) {
 194
 195                 /* Exit the interpreter, allow handler to execute methods */
 196
 197                 acpi_ex_exit_interpreter();
 198
 199                 /*
 200                  * Handler can map the exception code to anything it wants, including
 201                  * AE_OK, in which case the executing method will not be aborted.
 202                  */
 203                 aml_offset = (u32)ACPI_PTR_DIFF(walk_state->aml,
 204                                                 walk_state->parser_state.
 205                                                 aml_start);
 206
 207                 if (walk_state->method_node) {
 208                         name = walk_state->method_node->name.integer;
 209                 } else if (walk_state->deferred_node) {
 210                         name = walk_state->deferred_node->name.integer;
 211                 }
 212
 213                 status = acpi_gbl_exception_handler(status, name,
 214                                                     walk_state->opcode,
 215                                                     aml_offset, NULL);
 216                 acpi_ex_enter_interpreter();
 217         }
 218
 219         acpi_ds_clear_implicit_return(walk_state);
 220
 221         if (ACPI_FAILURE(status)) {
 222                 acpi_ds_dump_method_stack(status, walk_state, walk_state->op);
 223
 224                 /* Display method locals/args if debugger is present */
 225
 226 #ifdef ACPI_DEBUGGER
 227                 acpi_db_dump_method_info(status, walk_state);
 228 #endif
 229         }
 230
 231         return (status);
 232 }
 233
 234 /*******************************************************************************
 235  *
 236  * FUNCTION:    acpi_ds_create_method_mutex
 237  *
 238  * PARAMETERS:  obj_desc            - The method object
 239  *
 240  * RETURN:      Status
 241  *
 242  * DESCRIPTION: Create a mutex object for a serialized control method
 243  *
 244  ******************************************************************************/
 245
 246 static acpi_status
 247 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc)
 248 {
 249         union acpi_operand_object *mutex_desc;
 250         acpi_status status;
 251
 252         ACPI_FUNCTION_TRACE(ds_create_method_mutex);
 253
 254         /* Create the new mutex object */
 255
 256         mutex_desc = acpi_ut_create_internal_object(ACPI_TYPE_MUTEX);
 257         if (!mutex_desc) {
 258                 return_ACPI_STATUS(AE_NO_MEMORY);
 259         }
 260
 261         /* Create the actual OS Mutex */
 262
 263         status = acpi_os_create_mutex(&mutex_desc->mutex.os_mutex);
 264         if (ACPI_FAILURE(status)) {
 265                 acpi_ut_delete_object_desc(mutex_desc);
 266                 return_ACPI_STATUS(status);
 267         }
 268
 269         mutex_desc->mutex.sync_level = method_desc->method.sync_level;
 270         method_desc->method.mutex = mutex_desc;
 271         return_ACPI_STATUS(AE_OK);
 272 }
 273
 274 /*******************************************************************************
 275  *
 276  * FUNCTION:    acpi_ds_begin_method_execution
 277  *
 278  * PARAMETERS:  method_node         - Node of the method
 279  *              obj_desc            - The method object
 280  *              walk_state          - current state, NULL if not yet executing
 281  *                                    a method.
 282  *
 283  * RETURN:      Status
 284  *
 285  * DESCRIPTION: Prepare a method for execution. Parses the method if necessary,
 286  *              increments the thread count, and waits at the method semaphore
 287  *              for clearance to execute.
 288  *
 289  ******************************************************************************/
 290
 291 acpi_status
 292 acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
 293                                union acpi_operand_object *obj_desc,
 294                                struct acpi_walk_state *walk_state)
 295 {
 296         acpi_status status = AE_OK;
 297
 298         ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);
 299
 300         if (!method_node) {
 301                 return_ACPI_STATUS(AE_NULL_ENTRY);
 302         }
 303
 304         acpi_ex_start_trace_method(method_node, obj_desc, walk_state);
 305
 306         /* Prevent wraparound of thread count */
 307
 308         if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {
 309                 ACPI_ERROR((AE_INFO,
 310                             "Method reached maximum reentrancy limit (255)"));
 311                 return_ACPI_STATUS(AE_AML_METHOD_LIMIT);
 312         }
 313
 314         /*
 315          * If this method is serialized, we need to acquire the method mutex.
 316          */
 317         if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {
 318                 /*
 319                  * Create a mutex for the method if it is defined to be Serialized
 320                  * and a mutex has not already been created. We defer the mutex creation
 321                  * until a method is actually executed, to minimize the object count
 322                  */
 323                 if (!obj_desc->method.mutex) {
 324                         status = acpi_ds_create_method_mutex(obj_desc);
 325                         if (ACPI_FAILURE(status)) {
 326                                 return_ACPI_STATUS(status);
 327                         }
 328                 }
 329
 330                 /*
 331                  * The current_sync_level (per-thread) must be less than or equal to
 332                  * the sync level of the method. This mechanism provides some
 333                  * deadlock prevention.
 334                  *
 335                  * If the method was auto-serialized, we just ignore the sync level
 336                  * mechanism, because auto-serialization of methods can interfere
 337                  * with ASL code that actually uses sync levels.
 338                  *
 339                  * Top-level method invocation has no walk state at this point
 340                  */
 341                 if (walk_state &&
 342                     (!(obj_desc->method.
 343                        info_flags & ACPI_METHOD_IGNORE_SYNC_LEVEL))
 344                     && (walk_state->thread->current_sync_level >
 345                         obj_desc->method.mutex->mutex.sync_level)) {
 346                         ACPI_ERROR((AE_INFO,
 347                                     "Cannot acquire Mutex for method [%4.4s]"
 348                                     ", current SyncLevel is too large (%u)",
 349                                     acpi_ut_get_node_name(method_node),
 350                                     walk_state->thread->current_sync_level));
 351
 352                         return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
 353                 }
 354
 355                 /*
 356                  * Obtain the method mutex if necessary. Do not acquire mutex for a
 357                  * recursive call.
 358                  */
 359                 if (!walk_state ||
 360                     !obj_desc->method.mutex->mutex.thread_id ||
 361                     (walk_state->thread->thread_id !=
 362                      obj_desc->method.mutex->mutex.thread_id)) {
 363                         /*
 364                          * Acquire the method mutex. This releases the interpreter if we
 365                          * block (and reacquires it before it returns)
 366                          */
 367                         status =
 368                             acpi_ex_system_wait_mutex(obj_desc->method.mutex->
 369                                                       mutex.os_mutex,
 370                                                       ACPI_WAIT_FOREVER);
 371                         if (ACPI_FAILURE(status)) {
 372                                 return_ACPI_STATUS(status);
 373                         }
 374
 375                         /* Update the mutex and walk info and save the original sync_level */
 376
 377                         if (walk_state) {
 378                                 obj_desc->method.mutex->mutex.
 379                                     original_sync_level =
 380                                     walk_state->thread->current_sync_level;
 381
 382                                 obj_desc->method.mutex->mutex.thread_id =
 383                                     walk_state->thread->thread_id;
 384
 385                                 /*
 386                                  * Update the current sync_level only if this is not an auto-
 387                                  * serialized method. In the auto case, we have to ignore
 388                                  * the sync level for the method mutex (created for the
 389                                  * auto-serialization) because we have no idea of what the
 390                                  * sync level should be. Therefore, just ignore it.
 391                                  */
 392                                 if (!(obj_desc->method.info_flags &
 393                                       ACPI_METHOD_IGNORE_SYNC_LEVEL)) {
 394                                         walk_state->thread->current_sync_level =
 395                                             obj_desc->method.sync_level;
 396                                 }
 397                         } else {
 398                                 obj_desc->method.mutex->mutex.
 399                                     original_sync_level =
 400                                     obj_desc->method.mutex->mutex.sync_level;
 401
 402                                 obj_desc->method.mutex->mutex.thread_id =
 403                                     acpi_os_get_thread_id();
 404                         }
 405                 }
 406
 407                 /* Always increase acquisition depth */
 408
 409                 obj_desc->method.mutex->mutex.acquisition_depth++;
 410         }
 411
 412         /*
 413          * Allocate an Owner ID for this method, only if this is the first thread
 414          * to begin concurrent execution. We only need one owner_id, even if the
 415          * method is invoked recursively.
 416          */
 417         if (!obj_desc->method.owner_id) {
 418                 status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);
 419                 if (ACPI_FAILURE(status)) {
 420                         goto cleanup;
 421                 }
 422         }
 423
 424         /*
 425          * Increment the method parse tree thread count since it has been
 426          * reentered one more time (even if it is the same thread)
 427          */
 428         obj_desc->method.thread_count++;
 429         acpi_method_count++;
 430         return_ACPI_STATUS(status);
 431
 432 cleanup:
 433         /* On error, must release the method mutex (if present) */
 434
 435         if (obj_desc->method.mutex) {
 436                 acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);
 437         }
 438         return_ACPI_STATUS(status);
 439 }
 440
 441 /*******************************************************************************
 442  *
 443  * FUNCTION:    acpi_ds_call_control_method
 444  *
 445  * PARAMETERS:  thread              - Info for this thread
 446  *              this_walk_state     - Current walk state
 447  *              op                  - Current Op to be walked
 448  *
 449  * RETURN:      Status
 450  *
 451  * DESCRIPTION: Transfer execution to a called control method
 452  *
 453  ******************************************************************************/
 454
 455 acpi_status
 456 acpi_ds_call_control_method(struct acpi_thread_state *thread,
 457                             struct acpi_walk_state *this_walk_state,
 458                             union acpi_parse_object *op)
 459 {
 460         acpi_status status;
 461         struct acpi_namespace_node *method_node;
 462         struct acpi_walk_state *next_walk_state = NULL;
 463         union acpi_operand_object *obj_desc;
 464         struct acpi_evaluate_info *info;
 465         u32 i;
 466
 467         ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);
 468
 469         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 470                           "Calling method %p, currentstate=%p\n",
 471                           this_walk_state->prev_op, this_walk_state));
 472
 473         /*
 474          * Get the namespace entry for the control method we are about to call
 475          */
 476         method_node = this_walk_state->method_call_node;
 477         if (!method_node) {
 478                 return_ACPI_STATUS(AE_NULL_ENTRY);
 479         }
 480
 481         obj_desc = acpi_ns_get_attached_object(method_node);
 482         if (!obj_desc) {
 483                 return_ACPI_STATUS(AE_NULL_OBJECT);
 484         }
 485
 486         /* Init for new method, possibly wait on method mutex */
 487
 488         status =
 489             acpi_ds_begin_method_execution(method_node, obj_desc,
 490                                            this_walk_state);
 491         if (ACPI_FAILURE(status)) {
 492                 return_ACPI_STATUS(status);
 493         }
 494
 495         /* Begin method parse/execution. Create a new walk state */
 496
 497         next_walk_state =
 498             acpi_ds_create_walk_state(obj_desc->method.owner_id, NULL, obj_desc,
 499                                       thread);
 500         if (!next_walk_state) {
 501                 status = AE_NO_MEMORY;
 502                 goto cleanup;
 503         }
 504
 505         /*
 506          * The resolved arguments were put on the previous walk state's operand
 507          * stack. Operands on the previous walk state stack always
 508          * start at index 0. Also, null terminate the list of arguments
 509          */
 510         this_walk_state->operands[this_walk_state->num_operands] = NULL;
 511
 512         /*
 513          * Allocate and initialize the evaluation information block
 514          * TBD: this is somewhat inefficient, should change interface to
 515          * ds_init_aml_walk. For now, keeps this struct off the CPU stack
 516          */
 517         info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
 518         if (!info) {
 519                 status = AE_NO_MEMORY;
 520                 goto pop_walk_state;
 521         }
 522
 523         info->parameters = &this_walk_state->operands[0];
 524
 525         status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,
 526                                        obj_desc->method.aml_start,
 527                                        obj_desc->method.aml_length, info,
 528                                        ACPI_IMODE_EXECUTE);
 529
 530         ACPI_FREE(info);
 531         if (ACPI_FAILURE(status)) {
 532                 goto pop_walk_state;
 533         }
 534
 535         next_walk_state->method_nesting_depth =
 536             this_walk_state->method_nesting_depth + 1;
 537
 538         /*
 539          * Delete the operands on the previous walkstate operand stack
 540          * (they were copied to new objects)
 541          */
 542         for (i = 0; i < obj_desc->method.param_count; i++) {
 543                 acpi_ut_remove_reference(this_walk_state->operands[i]);
 544                 this_walk_state->operands[i] = NULL;
 545         }
 546
 547         /* Clear the operand stack */
 548
 549         this_walk_state->num_operands = 0;
 550
 551         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 552                           "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",
 553                           method_node->name.ascii, next_walk_state));
 554
 555         this_walk_state->method_pathname =
 556             acpi_ns_get_normalized_pathname(method_node, TRUE);
 557         this_walk_state->method_is_nested = TRUE;
 558
 559         /* Optional object evaluation log */
 560
 561         ACPI_DEBUG_PRINT_RAW((ACPI_DB_EVALUATION,
 562                               "%-26s:  %*s%s\n", "   Nested method call",
 563                               next_walk_state->method_nesting_depth * 3, " ",
 564                               &this_walk_state->method_pathname[1]));
 565
 566         /* Invoke an internal method if necessary */
 567
 568         if (obj_desc->method.info_flags & ACPI_METHOD_INTERNAL_ONLY) {
 569                 status =
 570                     obj_desc->method.dispatch.implementation(next_walk_state);
 571                 if (status == AE_OK) {
 572                         status = AE_CTRL_TERMINATE;
 573                 }
 574         }
 575
 576         return_ACPI_STATUS(status);
 577
 578 pop_walk_state:
 579
 580         /* On error, pop the walk state to be deleted from thread */
 581
 582         acpi_ds_pop_walk_state(thread);
 583
 584 cleanup:
 585
 586         /* On error, we must terminate the method properly */
 587
 588         acpi_ds_terminate_control_method(obj_desc, next_walk_state);
 589         acpi_ds_delete_walk_state(next_walk_state);
 590
 591         return_ACPI_STATUS(status);
 592 }
 593
 594 /*******************************************************************************
 595  *
 596  * FUNCTION:    acpi_ds_restart_control_method
 597  *
 598  * PARAMETERS:  walk_state          - State for preempted method (caller)
 599  *              return_desc         - Return value from the called method
 600  *
 601  * RETURN:      Status
 602  *
 603  * DESCRIPTION: Restart a method that was preempted by another (nested) method
 604  *              invocation. Handle the return value (if any) from the callee.
 605  *
 606  ******************************************************************************/
 607
 608 acpi_status
 609 acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,
 610                                union acpi_operand_object *return_desc)
 611 {
 612         acpi_status status;
 613         int same_as_implicit_return;
 614
 615         ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);
 616
 617         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 618                           "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",
 619                           acpi_ut_get_node_name(walk_state->method_node),
 620                           walk_state->method_call_op, return_desc));
 621
 622         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 623                           "    ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",
 624                           walk_state->return_used,
 625                           walk_state->results, walk_state));
 626
 627         /* Did the called method return a value? */
 628
 629         if (return_desc) {
 630
 631                 /* Is the implicit return object the same as the return desc? */
 632
 633                 same_as_implicit_return =
 634                     (walk_state->implicit_return_obj == return_desc);
 635
 636                 /* Are we actually going to use the return value? */
 637
 638                 if (walk_state->return_used) {
 639
 640                         /* Save the return value from the previous method */
 641
 642                         status = acpi_ds_result_push(return_desc, walk_state);
 643                         if (ACPI_FAILURE(status)) {
 644                                 acpi_ut_remove_reference(return_desc);
 645                                 return_ACPI_STATUS(status);
 646                         }
 647
 648                         /*
 649                          * Save as THIS method's return value in case it is returned
 650                          * immediately to yet another method
 651                          */
 652                         walk_state->return_desc = return_desc;
 653                 }
 654
 655                 /*
 656                  * The following code is the optional support for the so-called
 657                  * "implicit return". Some AML code assumes that the last value of the
 658                  * method is "implicitly" returned to the caller, in the absence of an
 659                  * explicit return value.
 660                  *
 661                  * Just save the last result of the method as the return value.
 662                  *
 663                  * NOTE: this is optional because the ASL language does not actually
 664                  * support this behavior.
 665                  */
 666                 else if (!acpi_ds_do_implicit_return
 667                          (return_desc, walk_state, FALSE)
 668                          || same_as_implicit_return) {
 669                         /*
 670                          * Delete the return value if it will not be used by the
 671                          * calling method or remove one reference if the explicit return
 672                          * is the same as the implicit return value.
 673                          */
 674                         acpi_ut_remove_reference(return_desc);
 675                 }
 676         }
 677
 678         return_ACPI_STATUS(AE_OK);
 679 }
 680
 681 /*******************************************************************************
 682  *
 683  * FUNCTION:    acpi_ds_terminate_control_method
 684  *
 685  * PARAMETERS:  method_desc         - Method object
 686  *              walk_state          - State associated with the method
 687  *
 688  * RETURN:      None
 689  *
 690  * DESCRIPTION: Terminate a control method. Delete everything that the method
 691  *              created, delete all locals and arguments, and delete the parse
 692  *              tree if requested.
 693  *
 694  * MUTEX:       Interpreter is locked
 695  *
 696  ******************************************************************************/
 697
 698 void
 699 acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
 700                                  struct acpi_walk_state *walk_state)
 701 {
 702
 703         ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);
 704
 705         /* method_desc is required, walk_state is optional */
 706
 707         if (!method_desc) {
 708                 return_VOID;
 709         }
 710
 711         if (walk_state) {
 712
 713                 /* Delete all arguments and locals */
 714
 715                 acpi_ds_method_data_delete_all(walk_state);
 716
 717                 /*
 718                  * Delete any namespace objects created anywhere within the
 719                  * namespace by the execution of this method. Unless:
 720                  * 1) This method is a module-level executable code method, in which
 721                  *    case we want make the objects permanent.
 722                  * 2) There are other threads executing the method, in which case we
 723                  *    will wait until the last thread has completed.
 724                  */
 725                 if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)
 726                     && (method_desc->method.thread_count == 1)) {
 727
 728                         /* Delete any direct children of (created by) this method */
 729
 730                         (void)acpi_ex_exit_interpreter();
 731                         acpi_ns_delete_namespace_subtree(walk_state->
 732                                                          method_node);
 733                         (void)acpi_ex_enter_interpreter();
 734
 735                         /*
 736                          * Delete any objects that were created by this method
 737                          * elsewhere in the namespace (if any were created).
 738                          * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the
 739                          * deletion such that we don't have to perform an entire
 740                          * namespace walk for every control method execution.
 741                          */
 742                         if (method_desc->method.
 743                             info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {
 744                                 (void)acpi_ex_exit_interpreter();
 745                                 acpi_ns_delete_namespace_by_owner(method_desc->
 746                                                                   method.
 747                                                                   owner_id);
 748                                 (void)acpi_ex_enter_interpreter();
 749                                 method_desc->method.info_flags &=
 750                                     ~ACPI_METHOD_MODIFIED_NAMESPACE;
 751                         }
 752                 }
 753
 754                 /*
 755                  * If method is serialized, release the mutex and restore the
 756                  * current sync level for this thread
 757                  */
 758                 if (method_desc->method.mutex) {
 759
 760                         /* Acquisition Depth handles recursive calls */
 761
 762                         method_desc->method.mutex->mutex.acquisition_depth--;
 763                         if (!method_desc->method.mutex->mutex.acquisition_depth) {
 764                                 walk_state->thread->current_sync_level =
 765                                     method_desc->method.mutex->mutex.
 766                                     original_sync_level;
 767
 768                                 acpi_os_release_mutex(method_desc->method.
 769                                                       mutex->mutex.os_mutex);
 770                                 method_desc->method.mutex->mutex.thread_id = 0;
 771                         }
 772                 }
 773         }
 774
 775         /* Decrement the thread count on the method */
 776
 777         if (method_desc->method.thread_count) {
 778                 method_desc->method.thread_count--;
 779         } else {
 780                 ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));
 781         }
 782
 783         /* Are there any other threads currently executing this method? */
 784
 785         if (method_desc->method.thread_count) {
 786                 /*
 787                  * Additional threads. Do not release the owner_id in this case,
 788                  * we immediately reuse it for the next thread executing this method
 789                  */
 790                 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 791                                   "*** Completed execution of one thread, %u threads remaining\n",
 792                                   method_desc->method.thread_count));
 793         } else {
 794                 /* This is the only executing thread for this method */
 795
 796                 /*
 797                  * Support to dynamically change a method from not_serialized to
 798                  * Serialized if it appears that the method is incorrectly written and
 799                  * does not support multiple thread execution. The best example of this
 800                  * is if such a method creates namespace objects and blocks. A second
 801                  * thread will fail with an AE_ALREADY_EXISTS exception.
 802                  *
 803                  * This code is here because we must wait until the last thread exits
 804                  * before marking the method as serialized.
 805                  */
 806                 if (method_desc->method.
 807                     info_flags & ACPI_METHOD_SERIALIZED_PENDING) {
 808                         if (walk_state) {
 809                                 ACPI_INFO(("Marking method %4.4s as Serialized "
 810                                            "because of AE_ALREADY_EXISTS error",
 811                                            walk_state->method_node->name.
 812                                            ascii));
 813                         }
 814
 815                         /*
 816                          * Method tried to create an object twice and was marked as
 817                          * "pending serialized". The probable cause is that the method
 818                          * cannot handle reentrancy.
 819                          *
 820                          * The method was created as not_serialized, but it tried to create
 821                          * a named object and then blocked, causing the second thread
 822                          * entrance to begin and then fail. Workaround this problem by
 823                          * marking the method permanently as Serialized when the last
 824                          * thread exits here.
 825                          */
 826                         method_desc->method.info_flags &=
 827                             ~ACPI_METHOD_SERIALIZED_PENDING;
 828
 829                         method_desc->method.info_flags |=
 830                             (ACPI_METHOD_SERIALIZED |
 831                              ACPI_METHOD_IGNORE_SYNC_LEVEL);
 832                         method_desc->method.sync_level = 0;
 833                 }
 834
 835                 /* No more threads, we can free the owner_id */
 836
 837                 if (!
 838                     (method_desc->method.
 839                      info_flags & ACPI_METHOD_MODULE_LEVEL)) {
 840                         acpi_ut_release_owner_id(&method_desc->method.owner_id);
 841                 }
 842         }
 843
 844         acpi_ex_stop_trace_method((struct acpi_namespace_node *)method_desc->
 845                                   method.node, method_desc, walk_state);
 846
 847         return_VOID;
 848 }