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 - 2016, 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 #include "acparser.h"
  50 #include "amlcode.h"
  51 #include "acdebug.h"
  52
  53 #define _COMPONENT          ACPI_DISPATCHER
  54 ACPI_MODULE_NAME("dsmethod")
  55
  56 /* Local prototypes */
  57 static acpi_status
  58 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
  59                              union acpi_parse_object **out_op);
  60
  61 static acpi_status
  62 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc);
  63
  64 /*******************************************************************************
  65  *
  66  * FUNCTION:    acpi_ds_auto_serialize_method
  67  *
  68  * PARAMETERS:  node                        - Namespace Node of the method
  69  *              obj_desc                    - Method object attached to node
  70  *
  71  * RETURN:      Status
  72  *
  73  * DESCRIPTION: Parse a control method AML to scan for control methods that
  74  *              need serialization due to the creation of named objects.
  75  *
  76  * NOTE: It is a bit of overkill to mark all such methods serialized, since
  77  * there is only a problem if the method actually blocks during execution.
  78  * A blocking operation is, for example, a Sleep() operation, or any access
  79  * to an operation region. However, it is probably not possible to easily
  80  * detect whether a method will block or not, so we simply mark all suspicious
  81  * methods as serialized.
  82  *
  83  * NOTE2: This code is essentially a generic routine for parsing a single
  84  * control method.
  85  *
  86  ******************************************************************************/
  87
  88 acpi_status
  89 acpi_ds_auto_serialize_method(struct acpi_namespace_node *node,
  90                               union acpi_operand_object *obj_desc)
  91 {
  92         acpi_status status;
  93         union acpi_parse_object *op = NULL;
  94         struct acpi_walk_state *walk_state;
  95
  96         ACPI_FUNCTION_TRACE_PTR(ds_auto_serialize_method, node);
  97
  98         ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
  99                           "Method auto-serialization parse [%4.4s] %p\n",
 100                           acpi_ut_get_node_name(node), node));
 101
 102         /* Create/Init a root op for the method parse tree */
 103
 104         op = acpi_ps_alloc_op(AML_METHOD_OP, obj_desc->method.aml_start);
 105         if (!op) {
 106                 return_ACPI_STATUS(AE_NO_MEMORY);
 107         }
 108
 109         acpi_ps_set_name(op, node->name.integer);
 110         op->common.node = node;
 111
 112         /* Create and initialize a new walk state */
 113
 114         walk_state =
 115             acpi_ds_create_walk_state(node->owner_id, NULL, NULL, NULL);
 116         if (!walk_state) {
 117                 acpi_ps_free_op(op);
 118                 return_ACPI_STATUS(AE_NO_MEMORY);
 119         }
 120
 121         status = acpi_ds_init_aml_walk(walk_state, op, node,
 122                                        obj_desc->method.aml_start,
 123                                        obj_desc->method.aml_length, NULL, 0);
 124         if (ACPI_FAILURE(status)) {
 125                 acpi_ds_delete_walk_state(walk_state);
 126                 acpi_ps_free_op(op);
 127                 return_ACPI_STATUS(status);
 128         }
 129
 130         walk_state->descending_callback = acpi_ds_detect_named_opcodes;
 131
 132         /* Parse the method, scan for creation of named objects */
 133
 134         status = acpi_ps_parse_aml(walk_state);
 135
 136         acpi_ps_delete_parse_tree(op);
 137         return_ACPI_STATUS(status);
 138 }
 139
 140 /*******************************************************************************
 141  *
 142  * FUNCTION:    acpi_ds_detect_named_opcodes
 143  *
 144  * PARAMETERS:  walk_state      - Current state of the parse tree walk
 145  *              out_op          - Unused, required for parser interface
 146  *
 147  * RETURN:      Status
 148  *
 149  * DESCRIPTION: Descending callback used during the loading of ACPI tables.
 150  *              Currently used to detect methods that must be marked serialized
 151  *              in order to avoid problems with the creation of named objects.
 152  *
 153  ******************************************************************************/
 154
 155 static acpi_status
 156 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
 157                              union acpi_parse_object **out_op)
 158 {
 159
 160         ACPI_FUNCTION_NAME(acpi_ds_detect_named_opcodes);
 161
 162         /* We are only interested in opcodes that create a new name */
 163
 164         if (!
 165             (walk_state->op_info->
 166              flags & (AML_NAMED | AML_CREATE | AML_FIELD))) {
 167                 return (AE_OK);
 168         }
 169
 170         /*
 171          * At this point, we know we have a Named object opcode.
 172          * Mark the method as serialized. Later code will create a mutex for
 173          * this method to enforce serialization.
 174          *
 175          * Note, ACPI_METHOD_IGNORE_SYNC_LEVEL flag means that we will ignore the
 176          * Sync Level mechanism for this method, even though it is now serialized.
 177          * Otherwise, there can be conflicts with existing ASL code that actually
 178          * uses sync levels.
 179          */
 180         walk_state->method_desc->method.sync_level = 0;
 181         walk_state->method_desc->method.info_flags |=
 182             (ACPI_METHOD_SERIALIZED | ACPI_METHOD_IGNORE_SYNC_LEVEL);
 183
 184         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 185                           "Method serialized [%4.4s] %p - [%s] (%4.4X)\n",
 186                           walk_state->method_node->name.ascii,
 187                           walk_state->method_node, walk_state->op_info->name,
 188                           walk_state->opcode));
 189
 190         /* Abort the parse, no need to examine this method any further */
 191
 192         return (AE_CTRL_TERMINATE);
 193 }
 194
 195 /*******************************************************************************
 196  *
 197  * FUNCTION:    acpi_ds_method_error
 198  *
 199  * PARAMETERS:  status          - Execution status
 200  *              walk_state      - Current state
 201  *
 202  * RETURN:      Status
 203  *
 204  * DESCRIPTION: Called on method error. Invoke the global exception handler if
 205  *              present, dump the method data if the debugger is configured
 206  *
 207  *              Note: Allows the exception handler to change the status code
 208  *
 209  ******************************************************************************/
 210
 211 acpi_status
 212 acpi_ds_method_error(acpi_status status, struct acpi_walk_state * walk_state)
 213 {
 214         u32 aml_offset;
 215
 216         ACPI_FUNCTION_ENTRY();
 217
 218         /* Ignore AE_OK and control exception codes */
 219
 220         if (ACPI_SUCCESS(status) || (status & AE_CODE_CONTROL)) {
 221                 return (status);
 222         }
 223
 224         /* Invoke the global exception handler */
 225
 226         if (acpi_gbl_exception_handler) {
 227
 228                 /* Exit the interpreter, allow handler to execute methods */
 229
 230                 acpi_ex_exit_interpreter();
 231
 232                 /*
 233                  * Handler can map the exception code to anything it wants, including
 234                  * AE_OK, in which case the executing method will not be aborted.
 235                  */
 236                 aml_offset = (u32)ACPI_PTR_DIFF(walk_state->aml,
 237                                                 walk_state->parser_state.
 238                                                 aml_start);
 239
 240                 status = acpi_gbl_exception_handler(status,
 241                                                     walk_state->method_node ?
 242                                                     walk_state->method_node->
 243                                                     name.integer : 0,
 244                                                     walk_state->opcode,
 245                                                     aml_offset, NULL);
 246                 acpi_ex_enter_interpreter();
 247         }
 248
 249         acpi_ds_clear_implicit_return(walk_state);
 250
 251         if (ACPI_FAILURE(status)) {
 252                 acpi_ds_dump_method_stack(status, walk_state, walk_state->op);
 253
 254                 /* Display method locals/args if debugger is present */
 255
 256 #ifdef ACPI_DEBUGGER
 257                 acpi_db_dump_method_info(status, walk_state);
 258 #endif
 259         }
 260
 261         return (status);
 262 }
 263
 264 /*******************************************************************************
 265  *
 266  * FUNCTION:    acpi_ds_create_method_mutex
 267  *
 268  * PARAMETERS:  obj_desc            - The method object
 269  *
 270  * RETURN:      Status
 271  *
 272  * DESCRIPTION: Create a mutex object for a serialized control method
 273  *
 274  ******************************************************************************/
 275
 276 static acpi_status
 277 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc)
 278 {
 279         union acpi_operand_object *mutex_desc;
 280         acpi_status status;
 281
 282         ACPI_FUNCTION_TRACE(ds_create_method_mutex);
 283
 284         /* Create the new mutex object */
 285
 286         mutex_desc = acpi_ut_create_internal_object(ACPI_TYPE_MUTEX);
 287         if (!mutex_desc) {
 288                 return_ACPI_STATUS(AE_NO_MEMORY);
 289         }
 290
 291         /* Create the actual OS Mutex */
 292
 293         status = acpi_os_create_mutex(&mutex_desc->mutex.os_mutex);
 294         if (ACPI_FAILURE(status)) {
 295                 acpi_ut_delete_object_desc(mutex_desc);
 296                 return_ACPI_STATUS(status);
 297         }
 298
 299         mutex_desc->mutex.sync_level = method_desc->method.sync_level;
 300         method_desc->method.mutex = mutex_desc;
 301         return_ACPI_STATUS(AE_OK);
 302 }
 303
 304 /*******************************************************************************
 305  *
 306  * FUNCTION:    acpi_ds_begin_method_execution
 307  *
 308  * PARAMETERS:  method_node         - Node of the method
 309  *              obj_desc            - The method object
 310  *              walk_state          - current state, NULL if not yet executing
 311  *                                    a method.
 312  *
 313  * RETURN:      Status
 314  *
 315  * DESCRIPTION: Prepare a method for execution. Parses the method if necessary,
 316  *              increments the thread count, and waits at the method semaphore
 317  *              for clearance to execute.
 318  *
 319  ******************************************************************************/
 320
 321 acpi_status
 322 acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
 323                                union acpi_operand_object *obj_desc,
 324                                struct acpi_walk_state *walk_state)
 325 {
 326         acpi_status status = AE_OK;
 327
 328         ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);
 329
 330         if (!method_node) {
 331                 return_ACPI_STATUS(AE_NULL_ENTRY);
 332         }
 333
 334         acpi_ex_start_trace_method(method_node, obj_desc, walk_state);
 335
 336         /* Prevent wraparound of thread count */
 337
 338         if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {
 339                 ACPI_ERROR((AE_INFO,
 340                             "Method reached maximum reentrancy limit (255)"));
 341                 return_ACPI_STATUS(AE_AML_METHOD_LIMIT);
 342         }
 343
 344         /*
 345          * If this method is serialized, we need to acquire the method mutex.
 346          */
 347         if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {
 348                 /*
 349                  * Create a mutex for the method if it is defined to be Serialized
 350                  * and a mutex has not already been created. We defer the mutex creation
 351                  * until a method is actually executed, to minimize the object count
 352                  */
 353                 if (!obj_desc->method.mutex) {
 354                         status = acpi_ds_create_method_mutex(obj_desc);
 355                         if (ACPI_FAILURE(status)) {
 356                                 return_ACPI_STATUS(status);
 357                         }
 358                 }
 359
 360                 /*
 361                  * The current_sync_level (per-thread) must be less than or equal to
 362                  * the sync level of the method. This mechanism provides some
 363                  * deadlock prevention.
 364                  *
 365                  * If the method was auto-serialized, we just ignore the sync level
 366                  * mechanism, because auto-serialization of methods can interfere
 367                  * with ASL code that actually uses sync levels.
 368                  *
 369                  * Top-level method invocation has no walk state at this point
 370                  */
 371                 if (walk_state &&
 372                     (!(obj_desc->method.
 373                        info_flags & ACPI_METHOD_IGNORE_SYNC_LEVEL))
 374                     && (walk_state->thread->current_sync_level >
 375                         obj_desc->method.mutex->mutex.sync_level)) {
 376                         ACPI_ERROR((AE_INFO,
 377                                     "Cannot acquire Mutex for method [%4.4s]"
 378                                     ", current SyncLevel is too large (%u)",
 379                                     acpi_ut_get_node_name(method_node),
 380                                     walk_state->thread->current_sync_level));
 381
 382                         return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
 383                 }
 384
 385                 /*
 386                  * Obtain the method mutex if necessary. Do not acquire mutex for a
 387                  * recursive call.
 388                  */
 389                 if (!walk_state ||
 390                     !obj_desc->method.mutex->mutex.thread_id ||
 391                     (walk_state->thread->thread_id !=
 392                      obj_desc->method.mutex->mutex.thread_id)) {
 393                         /*
 394                          * Acquire the method mutex. This releases the interpreter if we
 395                          * block (and reacquires it before it returns)
 396                          */
 397                         status =
 398                             acpi_ex_system_wait_mutex(obj_desc->method.mutex->
 399                                                       mutex.os_mutex,
 400                                                       ACPI_WAIT_FOREVER);
 401                         if (ACPI_FAILURE(status)) {
 402                                 return_ACPI_STATUS(status);
 403                         }
 404
 405                         /* Update the mutex and walk info and save the original sync_level */
 406
 407                         if (walk_state) {
 408                                 obj_desc->method.mutex->mutex.
 409                                     original_sync_level =
 410                                     walk_state->thread->current_sync_level;
 411
 412                                 obj_desc->method.mutex->mutex.thread_id =
 413                                     walk_state->thread->thread_id;
 414
 415                                 /*
 416                                  * Update the current sync_level only if this is not an auto-
 417                                  * serialized method. In the auto case, we have to ignore
 418                                  * the sync level for the method mutex (created for the
 419                                  * auto-serialization) because we have no idea of what the
 420                                  * sync level should be. Therefore, just ignore it.
 421                                  */
 422                                 if (!(obj_desc->method.info_flags &
 423                                       ACPI_METHOD_IGNORE_SYNC_LEVEL)) {
 424                                         walk_state->thread->current_sync_level =
 425                                             obj_desc->method.sync_level;
 426                                 }
 427                         } else {
 428                                 obj_desc->method.mutex->mutex.
 429                                     original_sync_level =
 430                                     obj_desc->method.mutex->mutex.sync_level;
 431
 432                                 obj_desc->method.mutex->mutex.thread_id =
 433                                     acpi_os_get_thread_id();
 434                         }
 435                 }
 436
 437                 /* Always increase acquisition depth */
 438
 439                 obj_desc->method.mutex->mutex.acquisition_depth++;
 440         }
 441
 442         /*
 443          * Allocate an Owner ID for this method, only if this is the first thread
 444          * to begin concurrent execution. We only need one owner_id, even if the
 445          * method is invoked recursively.
 446          */
 447         if (!obj_desc->method.owner_id) {
 448                 status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);
 449                 if (ACPI_FAILURE(status)) {
 450                         goto cleanup;
 451                 }
 452         }
 453
 454         /*
 455          * Increment the method parse tree thread count since it has been
 456          * reentered one more time (even if it is the same thread)
 457          */
 458         obj_desc->method.thread_count++;
 459         acpi_method_count++;
 460         return_ACPI_STATUS(status);
 461
 462 cleanup:
 463         /* On error, must release the method mutex (if present) */
 464
 465         if (obj_desc->method.mutex) {
 466                 acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);
 467         }
 468         return_ACPI_STATUS(status);
 469 }
 470
 471 /*******************************************************************************
 472  *
 473  * FUNCTION:    acpi_ds_call_control_method
 474  *
 475  * PARAMETERS:  thread              - Info for this thread
 476  *              this_walk_state     - Current walk state
 477  *              op                  - Current Op to be walked
 478  *
 479  * RETURN:      Status
 480  *
 481  * DESCRIPTION: Transfer execution to a called control method
 482  *
 483  ******************************************************************************/
 484
 485 acpi_status
 486 acpi_ds_call_control_method(struct acpi_thread_state *thread,
 487                             struct acpi_walk_state *this_walk_state,
 488                             union acpi_parse_object *op)
 489 {
 490         acpi_status status;
 491         struct acpi_namespace_node *method_node;
 492         struct acpi_walk_state *next_walk_state = NULL;
 493         union acpi_operand_object *obj_desc;
 494         struct acpi_evaluate_info *info;
 495         u32 i;
 496
 497         ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);
 498
 499         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 500                           "Calling method %p, currentstate=%p\n",
 501                           this_walk_state->prev_op, this_walk_state));
 502
 503         /*
 504          * Get the namespace entry for the control method we are about to call
 505          */
 506         method_node = this_walk_state->method_call_node;
 507         if (!method_node) {
 508                 return_ACPI_STATUS(AE_NULL_ENTRY);
 509         }
 510
 511         obj_desc = acpi_ns_get_attached_object(method_node);
 512         if (!obj_desc) {
 513                 return_ACPI_STATUS(AE_NULL_OBJECT);
 514         }
 515
 516         /* Init for new method, possibly wait on method mutex */
 517
 518         status =
 519             acpi_ds_begin_method_execution(method_node, obj_desc,
 520                                            this_walk_state);
 521         if (ACPI_FAILURE(status)) {
 522                 return_ACPI_STATUS(status);
 523         }
 524
 525         /* Begin method parse/execution. Create a new walk state */
 526
 527         next_walk_state =
 528             acpi_ds_create_walk_state(obj_desc->method.owner_id, NULL, obj_desc,
 529                                       thread);
 530         if (!next_walk_state) {
 531                 status = AE_NO_MEMORY;
 532                 goto cleanup;
 533         }
 534
 535         /*
 536          * The resolved arguments were put on the previous walk state's operand
 537          * stack. Operands on the previous walk state stack always
 538          * start at index 0. Also, null terminate the list of arguments
 539          */
 540         this_walk_state->operands[this_walk_state->num_operands] = NULL;
 541
 542         /*
 543          * Allocate and initialize the evaluation information block
 544          * TBD: this is somewhat inefficient, should change interface to
 545          * ds_init_aml_walk. For now, keeps this struct off the CPU stack
 546          */
 547         info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
 548         if (!info) {
 549                 status = AE_NO_MEMORY;
 550                 goto cleanup;
 551         }
 552
 553         info->parameters = &this_walk_state->operands[0];
 554
 555         status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,
 556                                        obj_desc->method.aml_start,
 557                                        obj_desc->method.aml_length, info,
 558                                        ACPI_IMODE_EXECUTE);
 559
 560         ACPI_FREE(info);
 561         if (ACPI_FAILURE(status)) {
 562                 goto cleanup;
 563         }
 564
 565         /*
 566          * Delete the operands on the previous walkstate operand stack
 567          * (they were copied to new objects)
 568          */
 569         for (i = 0; i < obj_desc->method.param_count; i++) {
 570                 acpi_ut_remove_reference(this_walk_state->operands[i]);
 571                 this_walk_state->operands[i] = NULL;
 572         }
 573
 574         /* Clear the operand stack */
 575
 576         this_walk_state->num_operands = 0;
 577
 578         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 579                           "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",
 580                           method_node->name.ascii, next_walk_state));
 581
 582         /* Invoke an internal method if necessary */
 583
 584         if (obj_desc->method.info_flags & ACPI_METHOD_INTERNAL_ONLY) {
 585                 status =
 586                     obj_desc->method.dispatch.implementation(next_walk_state);
 587                 if (status == AE_OK) {
 588                         status = AE_CTRL_TERMINATE;
 589                 }
 590         }
 591
 592         return_ACPI_STATUS(status);
 593
 594 cleanup:
 595
 596         /* On error, we must terminate the method properly */
 597
 598         acpi_ds_terminate_control_method(obj_desc, next_walk_state);
 599         acpi_ds_delete_walk_state(next_walk_state);
 600
 601         return_ACPI_STATUS(status);
 602 }
 603
 604 /*******************************************************************************
 605  *
 606  * FUNCTION:    acpi_ds_restart_control_method
 607  *
 608  * PARAMETERS:  walk_state          - State for preempted method (caller)
 609  *              return_desc         - Return value from the called method
 610  *
 611  * RETURN:      Status
 612  *
 613  * DESCRIPTION: Restart a method that was preempted by another (nested) method
 614  *              invocation. Handle the return value (if any) from the callee.
 615  *
 616  ******************************************************************************/
 617
 618 acpi_status
 619 acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,
 620                                union acpi_operand_object *return_desc)
 621 {
 622         acpi_status status;
 623         int same_as_implicit_return;
 624
 625         ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);
 626
 627         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 628                           "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",
 629                           acpi_ut_get_node_name(walk_state->method_node),
 630                           walk_state->method_call_op, return_desc));
 631
 632         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 633                           "    ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",
 634                           walk_state->return_used,
 635                           walk_state->results, walk_state));
 636
 637         /* Did the called method return a value? */
 638
 639         if (return_desc) {
 640
 641                 /* Is the implicit return object the same as the return desc? */
 642
 643                 same_as_implicit_return =
 644                     (walk_state->implicit_return_obj == return_desc);
 645
 646                 /* Are we actually going to use the return value? */
 647
 648                 if (walk_state->return_used) {
 649
 650                         /* Save the return value from the previous method */
 651
 652                         status = acpi_ds_result_push(return_desc, walk_state);
 653                         if (ACPI_FAILURE(status)) {
 654                                 acpi_ut_remove_reference(return_desc);
 655                                 return_ACPI_STATUS(status);
 656                         }
 657
 658                         /*
 659                          * Save as THIS method's return value in case it is returned
 660                          * immediately to yet another method
 661                          */
 662                         walk_state->return_desc = return_desc;
 663                 }
 664
 665                 /*
 666                  * The following code is the optional support for the so-called
 667                  * "implicit return". Some AML code assumes that the last value of the
 668                  * method is "implicitly" returned to the caller, in the absence of an
 669                  * explicit return value.
 670                  *
 671                  * Just save the last result of the method as the return value.
 672                  *
 673                  * NOTE: this is optional because the ASL language does not actually
 674                  * support this behavior.
 675                  */
 676                 else if (!acpi_ds_do_implicit_return
 677                          (return_desc, walk_state, FALSE)
 678                          || same_as_implicit_return) {
 679                         /*
 680                          * Delete the return value if it will not be used by the
 681                          * calling method or remove one reference if the explicit return
 682                          * is the same as the implicit return value.
 683                          */
 684                         acpi_ut_remove_reference(return_desc);
 685                 }
 686         }
 687
 688         return_ACPI_STATUS(AE_OK);
 689 }
 690
 691 /*******************************************************************************
 692  *
 693  * FUNCTION:    acpi_ds_terminate_control_method
 694  *
 695  * PARAMETERS:  method_desc         - Method object
 696  *              walk_state          - State associated with the method
 697  *
 698  * RETURN:      None
 699  *
 700  * DESCRIPTION: Terminate a control method. Delete everything that the method
 701  *              created, delete all locals and arguments, and delete the parse
 702  *              tree if requested.
 703  *
 704  * MUTEX:       Interpreter is locked
 705  *
 706  ******************************************************************************/
 707
 708 void
 709 acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
 710                                  struct acpi_walk_state *walk_state)
 711 {
 712
 713         ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);
 714
 715         /* method_desc is required, walk_state is optional */
 716
 717         if (!method_desc) {
 718                 return_VOID;
 719         }
 720
 721         if (walk_state) {
 722
 723                 /* Delete all arguments and locals */
 724
 725                 acpi_ds_method_data_delete_all(walk_state);
 726
 727                 /*
 728                  * If method is serialized, release the mutex and restore the
 729                  * current sync level for this thread
 730                  */
 731                 if (method_desc->method.mutex) {
 732
 733                         /* Acquisition Depth handles recursive calls */
 734
 735                         method_desc->method.mutex->mutex.acquisition_depth--;
 736                         if (!method_desc->method.mutex->mutex.acquisition_depth) {
 737                                 walk_state->thread->current_sync_level =
 738                                     method_desc->method.mutex->mutex.
 739                                     original_sync_level;
 740
 741                                 acpi_os_release_mutex(method_desc->method.
 742                                                       mutex->mutex.os_mutex);
 743                                 method_desc->method.mutex->mutex.thread_id = 0;
 744                         }
 745                 }
 746
 747                 /*
 748                  * Delete any namespace objects created anywhere within the
 749                  * namespace by the execution of this method. Unless:
 750                  * 1) This method is a module-level executable code method, in which
 751                  *    case we want make the objects permanent.
 752                  * 2) There are other threads executing the method, in which case we
 753                  *    will wait until the last thread has completed.
 754                  */
 755                 if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)
 756                     && (method_desc->method.thread_count == 1)) {
 757
 758                         /* Delete any direct children of (created by) this method */
 759
 760                         acpi_ns_delete_namespace_subtree(walk_state->
 761                                                          method_node);
 762
 763                         /*
 764                          * Delete any objects that were created by this method
 765                          * elsewhere in the namespace (if any were created).
 766                          * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the
 767                          * deletion such that we don't have to perform an entire
 768                          * namespace walk for every control method execution.
 769                          */
 770                         if (method_desc->method.
 771                             info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {
 772                                 acpi_ns_delete_namespace_by_owner(method_desc->
 773                                                                   method.
 774                                                                   owner_id);
 775                                 method_desc->method.info_flags &=
 776                                     ~ACPI_METHOD_MODIFIED_NAMESPACE;
 777                         }
 778                 }
 779         }
 780
 781         /* Decrement the thread count on the method */
 782
 783         if (method_desc->method.thread_count) {
 784                 method_desc->method.thread_count--;
 785         } else {
 786                 ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));
 787         }
 788
 789         /* Are there any other threads currently executing this method? */
 790
 791         if (method_desc->method.thread_count) {
 792                 /*
 793                  * Additional threads. Do not release the owner_id in this case,
 794                  * we immediately reuse it for the next thread executing this method
 795                  */
 796                 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 797                                   "*** Completed execution of one thread, %u threads remaining\n",
 798                                   method_desc->method.thread_count));
 799         } else {
 800                 /* This is the only executing thread for this method */
 801
 802                 /*
 803                  * Support to dynamically change a method from not_serialized to
 804                  * Serialized if it appears that the method is incorrectly written and
 805                  * does not support multiple thread execution. The best example of this
 806                  * is if such a method creates namespace objects and blocks. A second
 807                  * thread will fail with an AE_ALREADY_EXISTS exception.
 808                  *
 809                  * This code is here because we must wait until the last thread exits
 810                  * before marking the method as serialized.
 811                  */
 812                 if (method_desc->method.
 813                     info_flags & ACPI_METHOD_SERIALIZED_PENDING) {
 814                         if (walk_state) {
 815                                 ACPI_INFO(("Marking method %4.4s as Serialized "
 816                                            "because of AE_ALREADY_EXISTS error",
 817                                            walk_state->method_node->name.
 818                                            ascii));
 819                         }
 820
 821                         /*
 822                          * Method tried to create an object twice and was marked as
 823                          * "pending serialized". The probable cause is that the method
 824                          * cannot handle reentrancy.
 825                          *
 826                          * The method was created as not_serialized, but it tried to create
 827                          * a named object and then blocked, causing the second thread
 828                          * entrance to begin and then fail. Workaround this problem by
 829                          * marking the method permanently as Serialized when the last
 830                          * thread exits here.
 831                          */
 832                         method_desc->method.info_flags &=
 833                             ~ACPI_METHOD_SERIALIZED_PENDING;
 834
 835                         method_desc->method.info_flags |=
 836                             (ACPI_METHOD_SERIALIZED |
 837                              ACPI_METHOD_IGNORE_SYNC_LEVEL);
 838                         method_desc->method.sync_level = 0;
 839                 }
 840
 841                 /* No more threads, we can free the owner_id */
 842
 843                 if (!
 844                     (method_desc->method.
 845                      info_flags & ACPI_METHOD_MODULE_LEVEL)) {
 846                         acpi_ut_release_owner_id(&method_desc->method.owner_id);
 847                 }
 848         }
 849
 850         acpi_ex_stop_trace_method((struct acpi_namespace_node *)method_desc->
 851                                   method.node, method_desc, walk_state);
 852
 853         return_VOID;
 854 }