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         acpi_ex_enter_interpreter();
 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                 status = AE_NO_MEMORY;
 109                 goto unlock;
 110         }
 111
 112         acpi_ps_set_name(op, node->name.integer);
 113         op->common.node = node;
 114
 115         /* Create and initialize a new walk state */
 116
 117         walk_state =
 118             acpi_ds_create_walk_state(node->owner_id, NULL, NULL, NULL);
 119         if (!walk_state) {
 120                 acpi_ps_free_op(op);
 121                 status = AE_NO_MEMORY;
 122                 goto unlock;
 123         }
 124
 125         status = acpi_ds_init_aml_walk(walk_state, op, node,
 126                                        obj_desc->method.aml_start,
 127                                        obj_desc->method.aml_length, NULL, 0);
 128         if (ACPI_FAILURE(status)) {
 129                 acpi_ds_delete_walk_state(walk_state);
 130                 acpi_ps_free_op(op);
 131                 return_ACPI_STATUS(status);
 132         }
 133
 134         walk_state->descending_callback = acpi_ds_detect_named_opcodes;
 135
 136         /* Parse the method, scan for creation of named objects */
 137
 138         status = acpi_ps_parse_aml(walk_state);
 139
 140         acpi_ps_delete_parse_tree(op);
 141 unlock:
 142         acpi_ex_exit_interpreter();
 143         return_ACPI_STATUS(status);
 144 }
 145
 146 /*******************************************************************************
 147  *
 148  * FUNCTION:    acpi_ds_detect_named_opcodes
 149  *
 150  * PARAMETERS:  walk_state      - Current state of the parse tree walk
 151  *              out_op          - Unused, required for parser interface
 152  *
 153  * RETURN:      Status
 154  *
 155  * DESCRIPTION: Descending callback used during the loading of ACPI tables.
 156  *              Currently used to detect methods that must be marked serialized
 157  *              in order to avoid problems with the creation of named objects.
 158  *
 159  ******************************************************************************/
 160
 161 static acpi_status
 162 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
 163                              union acpi_parse_object **out_op)
 164 {
 165
 166         ACPI_FUNCTION_NAME(acpi_ds_detect_named_opcodes);
 167
 168         /* We are only interested in opcodes that create a new name */
 169
 170         if (!
 171             (walk_state->op_info->
 172              flags & (AML_NAMED | AML_CREATE | AML_FIELD))) {
 173                 return (AE_OK);
 174         }
 175
 176         /*
 177          * At this point, we know we have a Named object opcode.
 178          * Mark the method as serialized. Later code will create a mutex for
 179          * this method to enforce serialization.
 180          *
 181          * Note, ACPI_METHOD_IGNORE_SYNC_LEVEL flag means that we will ignore the
 182          * Sync Level mechanism for this method, even though it is now serialized.
 183          * Otherwise, there can be conflicts with existing ASL code that actually
 184          * uses sync levels.
 185          */
 186         walk_state->method_desc->method.sync_level = 0;
 187         walk_state->method_desc->method.info_flags |=
 188             (ACPI_METHOD_SERIALIZED | ACPI_METHOD_IGNORE_SYNC_LEVEL);
 189
 190         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 191                           "Method serialized [%4.4s] %p - [%s] (%4.4X)\n",
 192                           walk_state->method_node->name.ascii,
 193                           walk_state->method_node, walk_state->op_info->name,
 194                           walk_state->opcode));
 195
 196         /* Abort the parse, no need to examine this method any further */
 197
 198         return (AE_CTRL_TERMINATE);
 199 }
 200
 201 /*******************************************************************************
 202  *
 203  * FUNCTION:    acpi_ds_method_error
 204  *
 205  * PARAMETERS:  status          - Execution status
 206  *              walk_state      - Current state
 207  *
 208  * RETURN:      Status
 209  *
 210  * DESCRIPTION: Called on method error. Invoke the global exception handler if
 211  *              present, dump the method data if the debugger is configured
 212  *
 213  *              Note: Allows the exception handler to change the status code
 214  *
 215  ******************************************************************************/
 216
 217 acpi_status
 218 acpi_ds_method_error(acpi_status status, struct acpi_walk_state *walk_state)
 219 {
 220         u32 aml_offset;
 221
 222         ACPI_FUNCTION_ENTRY();
 223
 224         /* Ignore AE_OK and control exception codes */
 225
 226         if (ACPI_SUCCESS(status) || (status & AE_CODE_CONTROL)) {
 227                 return (status);
 228         }
 229
 230         /* Invoke the global exception handler */
 231
 232         if (acpi_gbl_exception_handler) {
 233
 234                 /* Exit the interpreter, allow handler to execute methods */
 235
 236                 acpi_ex_exit_interpreter();
 237
 238                 /*
 239                  * Handler can map the exception code to anything it wants, including
 240                  * AE_OK, in which case the executing method will not be aborted.
 241                  */
 242                 aml_offset = (u32)ACPI_PTR_DIFF(walk_state->aml,
 243                                                 walk_state->parser_state.
 244                                                 aml_start);
 245
 246                 status = acpi_gbl_exception_handler(status,
 247                                                     walk_state->method_node ?
 248                                                     walk_state->method_node->
 249                                                     name.integer : 0,
 250                                                     walk_state->opcode,
 251                                                     aml_offset, NULL);
 252                 acpi_ex_enter_interpreter();
 253         }
 254
 255         acpi_ds_clear_implicit_return(walk_state);
 256
 257         if (ACPI_FAILURE(status)) {
 258                 acpi_ds_dump_method_stack(status, walk_state, walk_state->op);
 259
 260                 /* Display method locals/args if debugger is present */
 261
 262 #ifdef ACPI_DEBUGGER
 263                 acpi_db_dump_method_info(status, walk_state);
 264 #endif
 265         }
 266
 267         return (status);
 268 }
 269
 270 /*******************************************************************************
 271  *
 272  * FUNCTION:    acpi_ds_create_method_mutex
 273  *
 274  * PARAMETERS:  obj_desc            - The method object
 275  *
 276  * RETURN:      Status
 277  *
 278  * DESCRIPTION: Create a mutex object for a serialized control method
 279  *
 280  ******************************************************************************/
 281
 282 static acpi_status
 283 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc)
 284 {
 285         union acpi_operand_object *mutex_desc;
 286         acpi_status status;
 287
 288         ACPI_FUNCTION_TRACE(ds_create_method_mutex);
 289
 290         /* Create the new mutex object */
 291
 292         mutex_desc = acpi_ut_create_internal_object(ACPI_TYPE_MUTEX);
 293         if (!mutex_desc) {
 294                 return_ACPI_STATUS(AE_NO_MEMORY);
 295         }
 296
 297         /* Create the actual OS Mutex */
 298
 299         status = acpi_os_create_mutex(&mutex_desc->mutex.os_mutex);
 300         if (ACPI_FAILURE(status)) {
 301                 acpi_ut_delete_object_desc(mutex_desc);
 302                 return_ACPI_STATUS(status);
 303         }
 304
 305         mutex_desc->mutex.sync_level = method_desc->method.sync_level;
 306         method_desc->method.mutex = mutex_desc;
 307         return_ACPI_STATUS(AE_OK);
 308 }
 309
 310 /*******************************************************************************
 311  *
 312  * FUNCTION:    acpi_ds_begin_method_execution
 313  *
 314  * PARAMETERS:  method_node         - Node of the method
 315  *              obj_desc            - The method object
 316  *              walk_state          - current state, NULL if not yet executing
 317  *                                    a method.
 318  *
 319  * RETURN:      Status
 320  *
 321  * DESCRIPTION: Prepare a method for execution. Parses the method if necessary,
 322  *              increments the thread count, and waits at the method semaphore
 323  *              for clearance to execute.
 324  *
 325  ******************************************************************************/
 326
 327 acpi_status
 328 acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
 329                                union acpi_operand_object *obj_desc,
 330                                struct acpi_walk_state *walk_state)
 331 {
 332         acpi_status status = AE_OK;
 333
 334         ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);
 335
 336         if (!method_node) {
 337                 return_ACPI_STATUS(AE_NULL_ENTRY);
 338         }
 339
 340         acpi_ex_start_trace_method(method_node, obj_desc, walk_state);
 341
 342         /* Prevent wraparound of thread count */
 343
 344         if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {
 345                 ACPI_ERROR((AE_INFO,
 346                             "Method reached maximum reentrancy limit (255)"));
 347                 return_ACPI_STATUS(AE_AML_METHOD_LIMIT);
 348         }
 349
 350         /*
 351          * If this method is serialized, we need to acquire the method mutex.
 352          */
 353         if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {
 354                 /*
 355                  * Create a mutex for the method if it is defined to be Serialized
 356                  * and a mutex has not already been created. We defer the mutex creation
 357                  * until a method is actually executed, to minimize the object count
 358                  */
 359                 if (!obj_desc->method.mutex) {
 360                         status = acpi_ds_create_method_mutex(obj_desc);
 361                         if (ACPI_FAILURE(status)) {
 362                                 return_ACPI_STATUS(status);
 363                         }
 364                 }
 365
 366                 /*
 367                  * The current_sync_level (per-thread) must be less than or equal to
 368                  * the sync level of the method. This mechanism provides some
 369                  * deadlock prevention.
 370                  *
 371                  * If the method was auto-serialized, we just ignore the sync level
 372                  * mechanism, because auto-serialization of methods can interfere
 373                  * with ASL code that actually uses sync levels.
 374                  *
 375                  * Top-level method invocation has no walk state at this point
 376                  */
 377                 if (walk_state &&
 378                     (!(obj_desc->method.
 379                        info_flags & ACPI_METHOD_IGNORE_SYNC_LEVEL))
 380                     && (walk_state->thread->current_sync_level >
 381                         obj_desc->method.mutex->mutex.sync_level)) {
 382                         ACPI_ERROR((AE_INFO,
 383                                     "Cannot acquire Mutex for method [%4.4s]"
 384                                     ", current SyncLevel is too large (%u)",
 385                                     acpi_ut_get_node_name(method_node),
 386                                     walk_state->thread->current_sync_level));
 387
 388                         return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
 389                 }
 390
 391                 /*
 392                  * Obtain the method mutex if necessary. Do not acquire mutex for a
 393                  * recursive call.
 394                  */
 395                 if (!walk_state ||
 396                     !obj_desc->method.mutex->mutex.thread_id ||
 397                     (walk_state->thread->thread_id !=
 398                      obj_desc->method.mutex->mutex.thread_id)) {
 399                         /*
 400                          * Acquire the method mutex. This releases the interpreter if we
 401                          * block (and reacquires it before it returns)
 402                          */
 403                         status =
 404                             acpi_ex_system_wait_mutex(obj_desc->method.mutex->
 405                                                       mutex.os_mutex,
 406                                                       ACPI_WAIT_FOREVER);
 407                         if (ACPI_FAILURE(status)) {
 408                                 return_ACPI_STATUS(status);
 409                         }
 410
 411                         /* Update the mutex and walk info and save the original sync_level */
 412
 413                         if (walk_state) {
 414                                 obj_desc->method.mutex->mutex.
 415                                     original_sync_level =
 416                                     walk_state->thread->current_sync_level;
 417
 418                                 obj_desc->method.mutex->mutex.thread_id =
 419                                     walk_state->thread->thread_id;
 420
 421                                 /*
 422                                  * Update the current sync_level only if this is not an auto-
 423                                  * serialized method. In the auto case, we have to ignore
 424                                  * the sync level for the method mutex (created for the
 425                                  * auto-serialization) because we have no idea of what the
 426                                  * sync level should be. Therefore, just ignore it.
 427                                  */
 428                                 if (!(obj_desc->method.info_flags &
 429                                       ACPI_METHOD_IGNORE_SYNC_LEVEL)) {
 430                                         walk_state->thread->current_sync_level =
 431                                             obj_desc->method.sync_level;
 432                                 }
 433                         } else {
 434                                 obj_desc->method.mutex->mutex.
 435                                     original_sync_level =
 436                                     obj_desc->method.mutex->mutex.sync_level;
 437
 438                                 obj_desc->method.mutex->mutex.thread_id =
 439                                     acpi_os_get_thread_id();
 440                         }
 441                 }
 442
 443                 /* Always increase acquisition depth */
 444
 445                 obj_desc->method.mutex->mutex.acquisition_depth++;
 446         }
 447
 448         /*
 449          * Allocate an Owner ID for this method, only if this is the first thread
 450          * to begin concurrent execution. We only need one owner_id, even if the
 451          * method is invoked recursively.
 452          */
 453         if (!obj_desc->method.owner_id) {
 454                 status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);
 455                 if (ACPI_FAILURE(status)) {
 456                         goto cleanup;
 457                 }
 458         }
 459
 460         /*
 461          * Increment the method parse tree thread count since it has been
 462          * reentered one more time (even if it is the same thread)
 463          */
 464         obj_desc->method.thread_count++;
 465         acpi_method_count++;
 466         return_ACPI_STATUS(status);
 467
 468 cleanup:
 469         /* On error, must release the method mutex (if present) */
 470
 471         if (obj_desc->method.mutex) {
 472                 acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);
 473         }
 474         return_ACPI_STATUS(status);
 475 }
 476
 477 /*******************************************************************************
 478  *
 479  * FUNCTION:    acpi_ds_call_control_method
 480  *
 481  * PARAMETERS:  thread              - Info for this thread
 482  *              this_walk_state     - Current walk state
 483  *              op                  - Current Op to be walked
 484  *
 485  * RETURN:      Status
 486  *
 487  * DESCRIPTION: Transfer execution to a called control method
 488  *
 489  ******************************************************************************/
 490
 491 acpi_status
 492 acpi_ds_call_control_method(struct acpi_thread_state *thread,
 493                             struct acpi_walk_state *this_walk_state,
 494                             union acpi_parse_object *op)
 495 {
 496         acpi_status status;
 497         struct acpi_namespace_node *method_node;
 498         struct acpi_walk_state *next_walk_state = NULL;
 499         union acpi_operand_object *obj_desc;
 500         struct acpi_evaluate_info *info;
 501         u32 i;
 502
 503         ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);
 504
 505         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 506                           "Calling method %p, currentstate=%p\n",
 507                           this_walk_state->prev_op, this_walk_state));
 508
 509         /*
 510          * Get the namespace entry for the control method we are about to call
 511          */
 512         method_node = this_walk_state->method_call_node;
 513         if (!method_node) {
 514                 return_ACPI_STATUS(AE_NULL_ENTRY);
 515         }
 516
 517         obj_desc = acpi_ns_get_attached_object(method_node);
 518         if (!obj_desc) {
 519                 return_ACPI_STATUS(AE_NULL_OBJECT);
 520         }
 521
 522         /* Init for new method, possibly wait on method mutex */
 523
 524         status =
 525             acpi_ds_begin_method_execution(method_node, obj_desc,
 526                                            this_walk_state);
 527         if (ACPI_FAILURE(status)) {
 528                 return_ACPI_STATUS(status);
 529         }
 530
 531         /* Begin method parse/execution. Create a new walk state */
 532
 533         next_walk_state =
 534             acpi_ds_create_walk_state(obj_desc->method.owner_id, NULL, obj_desc,
 535                                       thread);
 536         if (!next_walk_state) {
 537                 status = AE_NO_MEMORY;
 538                 goto cleanup;
 539         }
 540
 541         /*
 542          * The resolved arguments were put on the previous walk state's operand
 543          * stack. Operands on the previous walk state stack always
 544          * start at index 0. Also, null terminate the list of arguments
 545          */
 546         this_walk_state->operands[this_walk_state->num_operands] = NULL;
 547
 548         /*
 549          * Allocate and initialize the evaluation information block
 550          * TBD: this is somewhat inefficient, should change interface to
 551          * ds_init_aml_walk. For now, keeps this struct off the CPU stack
 552          */
 553         info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
 554         if (!info) {
 555                 status = AE_NO_MEMORY;
 556                 goto cleanup;
 557         }
 558
 559         info->parameters = &this_walk_state->operands[0];
 560
 561         status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,
 562                                        obj_desc->method.aml_start,
 563                                        obj_desc->method.aml_length, info,
 564                                        ACPI_IMODE_EXECUTE);
 565
 566         ACPI_FREE(info);
 567         if (ACPI_FAILURE(status)) {
 568                 goto cleanup;
 569         }
 570
 571         /*
 572          * Delete the operands on the previous walkstate operand stack
 573          * (they were copied to new objects)
 574          */
 575         for (i = 0; i < obj_desc->method.param_count; i++) {
 576                 acpi_ut_remove_reference(this_walk_state->operands[i]);
 577                 this_walk_state->operands[i] = NULL;
 578         }
 579
 580         /* Clear the operand stack */
 581
 582         this_walk_state->num_operands = 0;
 583
 584         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 585                           "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",
 586                           method_node->name.ascii, next_walk_state));
 587
 588         /* Invoke an internal method if necessary */
 589
 590         if (obj_desc->method.info_flags & ACPI_METHOD_INTERNAL_ONLY) {
 591                 status =
 592                     obj_desc->method.dispatch.implementation(next_walk_state);
 593                 if (status == AE_OK) {
 594                         status = AE_CTRL_TERMINATE;
 595                 }
 596         }
 597
 598         return_ACPI_STATUS(status);
 599
 600 cleanup:
 601
 602         /* On error, we must terminate the method properly */
 603
 604         acpi_ds_terminate_control_method(obj_desc, next_walk_state);
 605         acpi_ds_delete_walk_state(next_walk_state);
 606
 607         return_ACPI_STATUS(status);
 608 }
 609
 610 /*******************************************************************************
 611  *
 612  * FUNCTION:    acpi_ds_restart_control_method
 613  *
 614  * PARAMETERS:  walk_state          - State for preempted method (caller)
 615  *              return_desc         - Return value from the called method
 616  *
 617  * RETURN:      Status
 618  *
 619  * DESCRIPTION: Restart a method that was preempted by another (nested) method
 620  *              invocation. Handle the return value (if any) from the callee.
 621  *
 622  ******************************************************************************/
 623
 624 acpi_status
 625 acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,
 626                                union acpi_operand_object *return_desc)
 627 {
 628         acpi_status status;
 629         int same_as_implicit_return;
 630
 631         ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);
 632
 633         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 634                           "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",
 635                           acpi_ut_get_node_name(walk_state->method_node),
 636                           walk_state->method_call_op, return_desc));
 637
 638         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 639                           "    ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",
 640                           walk_state->return_used,
 641                           walk_state->results, walk_state));
 642
 643         /* Did the called method return a value? */
 644
 645         if (return_desc) {
 646
 647                 /* Is the implicit return object the same as the return desc? */
 648
 649                 same_as_implicit_return =
 650                     (walk_state->implicit_return_obj == return_desc);
 651
 652                 /* Are we actually going to use the return value? */
 653
 654                 if (walk_state->return_used) {
 655
 656                         /* Save the return value from the previous method */
 657
 658                         status = acpi_ds_result_push(return_desc, walk_state);
 659                         if (ACPI_FAILURE(status)) {
 660                                 acpi_ut_remove_reference(return_desc);
 661                                 return_ACPI_STATUS(status);
 662                         }
 663
 664                         /*
 665                          * Save as THIS method's return value in case it is returned
 666                          * immediately to yet another method
 667                          */
 668                         walk_state->return_desc = return_desc;
 669                 }
 670
 671                 /*
 672                  * The following code is the optional support for the so-called
 673                  * "implicit return". Some AML code assumes that the last value of the
 674                  * method is "implicitly" returned to the caller, in the absence of an
 675                  * explicit return value.
 676                  *
 677                  * Just save the last result of the method as the return value.
 678                  *
 679                  * NOTE: this is optional because the ASL language does not actually
 680                  * support this behavior.
 681                  */
 682                 else if (!acpi_ds_do_implicit_return
 683                          (return_desc, walk_state, FALSE)
 684                          || same_as_implicit_return) {
 685                         /*
 686                          * Delete the return value if it will not be used by the
 687                          * calling method or remove one reference if the explicit return
 688                          * is the same as the implicit return value.
 689                          */
 690                         acpi_ut_remove_reference(return_desc);
 691                 }
 692         }
 693
 694         return_ACPI_STATUS(AE_OK);
 695 }
 696
 697 /*******************************************************************************
 698  *
 699  * FUNCTION:    acpi_ds_terminate_control_method
 700  *
 701  * PARAMETERS:  method_desc         - Method object
 702  *              walk_state          - State associated with the method
 703  *
 704  * RETURN:      None
 705  *
 706  * DESCRIPTION: Terminate a control method. Delete everything that the method
 707  *              created, delete all locals and arguments, and delete the parse
 708  *              tree if requested.
 709  *
 710  * MUTEX:       Interpreter is locked
 711  *
 712  ******************************************************************************/
 713
 714 void
 715 acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
 716                                  struct acpi_walk_state *walk_state)
 717 {
 718
 719         ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);
 720
 721         /* method_desc is required, walk_state is optional */
 722
 723         if (!method_desc) {
 724                 return_VOID;
 725         }
 726
 727         if (walk_state) {
 728
 729                 /* Delete all arguments and locals */
 730
 731                 acpi_ds_method_data_delete_all(walk_state);
 732
 733                 /*
 734                  * If method is serialized, release the mutex and restore the
 735                  * current sync level for this thread
 736                  */
 737                 if (method_desc->method.mutex) {
 738
 739                         /* Acquisition Depth handles recursive calls */
 740
 741                         method_desc->method.mutex->mutex.acquisition_depth--;
 742                         if (!method_desc->method.mutex->mutex.acquisition_depth) {
 743                                 walk_state->thread->current_sync_level =
 744                                     method_desc->method.mutex->mutex.
 745                                     original_sync_level;
 746
 747                                 acpi_os_release_mutex(method_desc->method.
 748                                                       mutex->mutex.os_mutex);
 749                                 method_desc->method.mutex->mutex.thread_id = 0;
 750                         }
 751                 }
 752
 753                 /*
 754                  * Delete any namespace objects created anywhere within the
 755                  * namespace by the execution of this method. Unless:
 756                  * 1) This method is a module-level executable code method, in which
 757                  *    case we want make the objects permanent.
 758                  * 2) There are other threads executing the method, in which case we
 759                  *    will wait until the last thread has completed.
 760                  */
 761                 if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)
 762                     && (method_desc->method.thread_count == 1)) {
 763
 764                         /* Delete any direct children of (created by) this method */
 765
 766                         (void)acpi_ex_exit_interpreter();
 767                         acpi_ns_delete_namespace_subtree(walk_state->
 768                                                          method_node);
 769                         (void)acpi_ex_enter_interpreter();
 770
 771                         /*
 772                          * Delete any objects that were created by this method
 773                          * elsewhere in the namespace (if any were created).
 774                          * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the
 775                          * deletion such that we don't have to perform an entire
 776                          * namespace walk for every control method execution.
 777                          */
 778                         if (method_desc->method.
 779                             info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {
 780                                 (void)acpi_ex_exit_interpreter();
 781                                 acpi_ns_delete_namespace_by_owner(method_desc->
 782                                                                   method.
 783                                                                   owner_id);
 784                                 (void)acpi_ex_enter_interpreter();
 785                                 method_desc->method.info_flags &=
 786                                     ~ACPI_METHOD_MODIFIED_NAMESPACE;
 787                         }
 788                 }
 789         }
 790
 791         /* Decrement the thread count on the method */
 792
 793         if (method_desc->method.thread_count) {
 794                 method_desc->method.thread_count--;
 795         } else {
 796                 ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));
 797         }
 798
 799         /* Are there any other threads currently executing this method? */
 800
 801         if (method_desc->method.thread_count) {
 802                 /*
 803                  * Additional threads. Do not release the owner_id in this case,
 804                  * we immediately reuse it for the next thread executing this method
 805                  */
 806                 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 807                                   "*** Completed execution of one thread, %u threads remaining\n",
 808                                   method_desc->method.thread_count));
 809         } else {
 810                 /* This is the only executing thread for this method */
 811
 812                 /*
 813                  * Support to dynamically change a method from not_serialized to
 814                  * Serialized if it appears that the method is incorrectly written and
 815                  * does not support multiple thread execution. The best example of this
 816                  * is if such a method creates namespace objects and blocks. A second
 817                  * thread will fail with an AE_ALREADY_EXISTS exception.
 818                  *
 819                  * This code is here because we must wait until the last thread exits
 820                  * before marking the method as serialized.
 821                  */
 822                 if (method_desc->method.
 823                     info_flags & ACPI_METHOD_SERIALIZED_PENDING) {
 824                         if (walk_state) {
 825                                 ACPI_INFO(("Marking method %4.4s as Serialized "
 826                                            "because of AE_ALREADY_EXISTS error",
 827                                            walk_state->method_node->name.
 828                                            ascii));
 829                         }
 830
 831                         /*
 832                          * Method tried to create an object twice and was marked as
 833                          * "pending serialized". The probable cause is that the method
 834                          * cannot handle reentrancy.
 835                          *
 836                          * The method was created as not_serialized, but it tried to create
 837                          * a named object and then blocked, causing the second thread
 838                          * entrance to begin and then fail. Workaround this problem by
 839                          * marking the method permanently as Serialized when the last
 840                          * thread exits here.
 841                          */
 842                         method_desc->method.info_flags &=
 843                             ~ACPI_METHOD_SERIALIZED_PENDING;
 844
 845                         method_desc->method.info_flags |=
 846                             (ACPI_METHOD_SERIALIZED |
 847                              ACPI_METHOD_IGNORE_SYNC_LEVEL);
 848                         method_desc->method.sync_level = 0;
 849                 }
 850
 851                 /* No more threads, we can free the owner_id */
 852
 853                 if (!
 854                     (method_desc->method.
 855                      info_flags & ACPI_METHOD_MODULE_LEVEL)) {
 856                         acpi_ut_release_owner_id(&method_desc->method.owner_id);
 857                 }
 858         }
 859
 860         acpi_ex_stop_trace_method((struct acpi_namespace_node *)method_desc->
 861                                   method.node, method_desc, walk_state);
 862
 863         return_VOID;
 864 }