kernel/drivers/acpi/acpica/dsmethod.c

   1 /******************************************************************************
   2  *
   3  * Module Name: dsmethod - Parser/Interpreter interface - control method parsing
   4  *
   5  *****************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2015, Intel Corp.
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions, and the following disclaimer,
  16  *    without modification.
  17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  18  *    substantially similar to the "NO WARRANTY" disclaimer below
  19  *    ("Disclaimer") and any redistribution must be conditioned upon
  20  *    including a substantially similar Disclaimer requirement for further
  21  *    binary redistribution.
  22  * 3. Neither the names of the above-listed copyright holders nor the names
  23  *    of any contributors may be used to endorse or promote products derived
  24  *    from this software without specific prior written permission.
  25  *
  26  * Alternatively, this software may be distributed under the terms of the
  27  * GNU General Public License ("GPL") version 2 as published by the Free
  28  * Software Foundation.
  29  *
  30  * NO WARRANTY
  31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  41  * POSSIBILITY OF SUCH DAMAGES.
  42  */
  43
  44 #include <acpi/acpi.h>
  45 #include "accommon.h"
  46 #include "acdispat.h"
  47 #include "acinterp.h"
  48 #include "acnamesp.h"
  49 #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 =
 122             acpi_ds_init_aml_walk(walk_state, op, node,
 123                                   obj_desc->method.aml_start,
 124                                   obj_desc->method.aml_length, NULL, 0);
 125         if (ACPI_FAILURE(status)) {
 126                 acpi_ds_delete_walk_state(walk_state);
 127                 acpi_ps_free_op(op);
 128                 return_ACPI_STATUS(status);
 129         }
 130
 131         walk_state->descending_callback = acpi_ds_detect_named_opcodes;
 132
 133         /* Parse the method, scan for creation of named objects */
 134
 135         status = acpi_ps_parse_aml(walk_state);
 136
 137         acpi_ps_delete_parse_tree(op);
 138         return_ACPI_STATUS(status);
 139 }
 140
 141 /*******************************************************************************
 142  *
 143  * FUNCTION:    acpi_ds_detect_named_opcodes
 144  *
 145  * PARAMETERS:  walk_state      - Current state of the parse tree walk
 146  *              out_op          - Unused, required for parser interface
 147  *
 148  * RETURN:      Status
 149  *
 150  * DESCRIPTION: Descending callback used during the loading of ACPI tables.
 151  *              Currently used to detect methods that must be marked serialized
 152  *              in order to avoid problems with the creation of named objects.
 153  *
 154  ******************************************************************************/
 155
 156 static acpi_status
 157 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
 158                              union acpi_parse_object **out_op)
 159 {
 160
 161         ACPI_FUNCTION_NAME(acpi_ds_detect_named_opcodes);
 162
 163         /* We are only interested in opcodes that create a new name */
 164
 165         if (!
 166             (walk_state->op_info->
 167              flags & (AML_NAMED | AML_CREATE | AML_FIELD))) {
 168                 return (AE_OK);
 169         }
 170
 171         /*
 172          * At this point, we know we have a Named object opcode.
 173          * Mark the method as serialized. Later code will create a mutex for
 174          * this method to enforce serialization.
 175          *
 176          * Note, ACPI_METHOD_IGNORE_SYNC_LEVEL flag means that we will ignore the
 177          * Sync Level mechanism for this method, even though it is now serialized.
 178          * Otherwise, there can be conflicts with existing ASL code that actually
 179          * uses sync levels.
 180          */
 181         walk_state->method_desc->method.sync_level = 0;
 182         walk_state->method_desc->method.info_flags |=
 183             (ACPI_METHOD_SERIALIZED | ACPI_METHOD_IGNORE_SYNC_LEVEL);
 184
 185         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 186                           "Method serialized [%4.4s] %p - [%s] (%4.4X)\n",
 187                           walk_state->method_node->name.ascii,
 188                           walk_state->method_node, walk_state->op_info->name,
 189                           walk_state->opcode));
 190
 191         /* Abort the parse, no need to examine this method any further */
 192
 193         return (AE_CTRL_TERMINATE);
 194 }
 195
 196 /*******************************************************************************
 197  *
 198  * FUNCTION:    acpi_ds_method_error
 199  *
 200  * PARAMETERS:  status          - Execution status
 201  *              walk_state      - Current state
 202  *
 203  * RETURN:      Status
 204  *
 205  * DESCRIPTION: Called on method error. Invoke the global exception handler if
 206  *              present, dump the method data if the debugger is configured
 207  *
 208  *              Note: Allows the exception handler to change the status code
 209  *
 210  ******************************************************************************/
 211
 212 acpi_status
 213 acpi_ds_method_error(acpi_status status, struct acpi_walk_state * walk_state)
 214 {
 215         u32 aml_offset;
 216
 217         ACPI_FUNCTION_ENTRY();
 218
 219         /* Ignore AE_OK and control exception codes */
 220
 221         if (ACPI_SUCCESS(status) || (status & AE_CODE_CONTROL)) {
 222                 return (status);
 223         }
 224
 225         /* Invoke the global exception handler */
 226
 227         if (acpi_gbl_exception_handler) {
 228
 229                 /* Exit the interpreter, allow handler to execute methods */
 230
 231                 acpi_ex_exit_interpreter();
 232
 233                 /*
 234                  * Handler can map the exception code to anything it wants, including
 235                  * AE_OK, in which case the executing method will not be aborted.
 236                  */
 237                 aml_offset = (u32)ACPI_PTR_DIFF(walk_state->aml,
 238                                                 walk_state->parser_state.
 239                                                 aml_start);
 240
 241                 status = acpi_gbl_exception_handler(status,
 242                                                     walk_state->method_node ?
 243                                                     walk_state->method_node->
 244                                                     name.integer : 0,
 245                                                     walk_state->opcode,
 246                                                     aml_offset, NULL);
 247                 acpi_ex_enter_interpreter();
 248         }
 249
 250         acpi_ds_clear_implicit_return(walk_state);
 251
 252         if (ACPI_FAILURE(status)) {
 253                 acpi_ds_dump_method_stack(status, walk_state, walk_state->op);
 254
 255                 /* Display method locals/args if debugger is present */
 256
 257 #ifdef ACPI_DEBUGGER
 258                 acpi_db_dump_method_info(status, walk_state);
 259 #endif
 260         }
 261
 262         return (status);
 263 }
 264
 265 /*******************************************************************************
 266  *
 267  * FUNCTION:    acpi_ds_create_method_mutex
 268  *
 269  * PARAMETERS:  obj_desc            - The method object
 270  *
 271  * RETURN:      Status
 272  *
 273  * DESCRIPTION: Create a mutex object for a serialized control method
 274  *
 275  ******************************************************************************/
 276
 277 static acpi_status
 278 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc)
 279 {
 280         union acpi_operand_object *mutex_desc;
 281         acpi_status status;
 282
 283         ACPI_FUNCTION_TRACE(ds_create_method_mutex);
 284
 285         /* Create the new mutex object */
 286
 287         mutex_desc = acpi_ut_create_internal_object(ACPI_TYPE_MUTEX);
 288         if (!mutex_desc) {
 289                 return_ACPI_STATUS(AE_NO_MEMORY);
 290         }
 291
 292         /* Create the actual OS Mutex */
 293
 294         status = acpi_os_create_mutex(&mutex_desc->mutex.os_mutex);
 295         if (ACPI_FAILURE(status)) {
 296                 acpi_ut_delete_object_desc(mutex_desc);
 297                 return_ACPI_STATUS(status);
 298         }
 299
 300         mutex_desc->mutex.sync_level = method_desc->method.sync_level;
 301         method_desc->method.mutex = mutex_desc;
 302         return_ACPI_STATUS(AE_OK);
 303 }
 304
 305 /*******************************************************************************
 306  *
 307  * FUNCTION:    acpi_ds_begin_method_execution
 308  *
 309  * PARAMETERS:  method_node         - Node of the method
 310  *              obj_desc            - The method object
 311  *              walk_state          - current state, NULL if not yet executing
 312  *                                    a method.
 313  *
 314  * RETURN:      Status
 315  *
 316  * DESCRIPTION: Prepare a method for execution. Parses the method if necessary,
 317  *              increments the thread count, and waits at the method semaphore
 318  *              for clearance to execute.
 319  *
 320  ******************************************************************************/
 321
 322 acpi_status
 323 acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
 324                                union acpi_operand_object *obj_desc,
 325                                struct acpi_walk_state *walk_state)
 326 {
 327         acpi_status status = AE_OK;
 328
 329         ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);
 330
 331         if (!method_node) {
 332                 return_ACPI_STATUS(AE_NULL_ENTRY);
 333         }
 334
 335         acpi_ex_start_trace_method(method_node, obj_desc, walk_state);
 336
 337         /* Prevent wraparound of thread count */
 338
 339         if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {
 340                 ACPI_ERROR((AE_INFO,
 341                             "Method reached maximum reentrancy limit (255)"));
 342                 return_ACPI_STATUS(AE_AML_METHOD_LIMIT);
 343         }
 344
 345         /*
 346          * If this method is serialized, we need to acquire the method mutex.
 347          */
 348         if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {
 349                 /*
 350                  * Create a mutex for the method if it is defined to be Serialized
 351                  * and a mutex has not already been created. We defer the mutex creation
 352                  * until a method is actually executed, to minimize the object count
 353                  */
 354                 if (!obj_desc->method.mutex) {
 355                         status = acpi_ds_create_method_mutex(obj_desc);
 356                         if (ACPI_FAILURE(status)) {
 357                                 return_ACPI_STATUS(status);
 358                         }
 359                 }
 360
 361                 /*
 362                  * The current_sync_level (per-thread) must be less than or equal to
 363                  * the sync level of the method. This mechanism provides some
 364                  * deadlock prevention.
 365                  *
 366                  * If the method was auto-serialized, we just ignore the sync level
 367                  * mechanism, because auto-serialization of methods can interfere
 368                  * with ASL code that actually uses sync levels.
 369                  *
 370                  * Top-level method invocation has no walk state at this point
 371                  */
 372                 if (walk_state &&
 373                     (!(obj_desc->method.
 374                        info_flags & ACPI_METHOD_IGNORE_SYNC_LEVEL))
 375                     && (walk_state->thread->current_sync_level >
 376                         obj_desc->method.mutex->mutex.sync_level)) {
 377                         ACPI_ERROR((AE_INFO,
 378                                     "Cannot acquire Mutex for method [%4.4s], 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                                 walk_state->thread->current_sync_level =
 415                                     obj_desc->method.sync_level;
 416                         } else {
 417                                 obj_desc->method.mutex->mutex.
 418                                     original_sync_level =
 419                                     obj_desc->method.mutex->mutex.sync_level;
 420                         }
 421                 }
 422
 423                 /* Always increase acquisition depth */
 424
 425                 obj_desc->method.mutex->mutex.acquisition_depth++;
 426         }
 427
 428         /*
 429          * Allocate an Owner ID for this method, only if this is the first thread
 430          * to begin concurrent execution. We only need one owner_id, even if the
 431          * method is invoked recursively.
 432          */
 433         if (!obj_desc->method.owner_id) {
 434                 status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);
 435                 if (ACPI_FAILURE(status)) {
 436                         goto cleanup;
 437                 }
 438         }
 439
 440         /*
 441          * Increment the method parse tree thread count since it has been
 442          * reentered one more time (even if it is the same thread)
 443          */
 444         obj_desc->method.thread_count++;
 445         acpi_method_count++;
 446         return_ACPI_STATUS(status);
 447
 448 cleanup:
 449         /* On error, must release the method mutex (if present) */
 450
 451         if (obj_desc->method.mutex) {
 452                 acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);
 453         }
 454         return_ACPI_STATUS(status);
 455 }
 456
 457 /*******************************************************************************
 458  *
 459  * FUNCTION:    acpi_ds_call_control_method
 460  *
 461  * PARAMETERS:  thread              - Info for this thread
 462  *              this_walk_state     - Current walk state
 463  *              op                  - Current Op to be walked
 464  *
 465  * RETURN:      Status
 466  *
 467  * DESCRIPTION: Transfer execution to a called control method
 468  *
 469  ******************************************************************************/
 470
 471 acpi_status
 472 acpi_ds_call_control_method(struct acpi_thread_state *thread,
 473                             struct acpi_walk_state *this_walk_state,
 474                             union acpi_parse_object *op)
 475 {
 476         acpi_status status;
 477         struct acpi_namespace_node *method_node;
 478         struct acpi_walk_state *next_walk_state = NULL;
 479         union acpi_operand_object *obj_desc;
 480         struct acpi_evaluate_info *info;
 481         u32 i;
 482
 483         ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);
 484
 485         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 486                           "Calling method %p, currentstate=%p\n",
 487                           this_walk_state->prev_op, this_walk_state));
 488
 489         /*
 490          * Get the namespace entry for the control method we are about to call
 491          */
 492         method_node = this_walk_state->method_call_node;
 493         if (!method_node) {
 494                 return_ACPI_STATUS(AE_NULL_ENTRY);
 495         }
 496
 497         obj_desc = acpi_ns_get_attached_object(method_node);
 498         if (!obj_desc) {
 499                 return_ACPI_STATUS(AE_NULL_OBJECT);
 500         }
 501
 502         /* Init for new method, possibly wait on method mutex */
 503
 504         status = acpi_ds_begin_method_execution(method_node, obj_desc,
 505                                                 this_walk_state);
 506         if (ACPI_FAILURE(status)) {
 507                 return_ACPI_STATUS(status);
 508         }
 509
 510         /* Begin method parse/execution. Create a new walk state */
 511
 512         next_walk_state = acpi_ds_create_walk_state(obj_desc->method.owner_id,
 513                                                     NULL, obj_desc, thread);
 514         if (!next_walk_state) {
 515                 status = AE_NO_MEMORY;
 516                 goto cleanup;
 517         }
 518
 519         /*
 520          * The resolved arguments were put on the previous walk state's operand
 521          * stack. Operands on the previous walk state stack always
 522          * start at index 0. Also, null terminate the list of arguments
 523          */
 524         this_walk_state->operands[this_walk_state->num_operands] = NULL;
 525
 526         /*
 527          * Allocate and initialize the evaluation information block
 528          * TBD: this is somewhat inefficient, should change interface to
 529          * ds_init_aml_walk. For now, keeps this struct off the CPU stack
 530          */
 531         info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
 532         if (!info) {
 533                 status = AE_NO_MEMORY;
 534                 goto cleanup;
 535         }
 536
 537         info->parameters = &this_walk_state->operands[0];
 538
 539         status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,
 540                                        obj_desc->method.aml_start,
 541                                        obj_desc->method.aml_length, info,
 542                                        ACPI_IMODE_EXECUTE);
 543
 544         ACPI_FREE(info);
 545         if (ACPI_FAILURE(status)) {
 546                 goto cleanup;
 547         }
 548
 549         /*
 550          * Delete the operands on the previous walkstate operand stack
 551          * (they were copied to new objects)
 552          */
 553         for (i = 0; i < obj_desc->method.param_count; i++) {
 554                 acpi_ut_remove_reference(this_walk_state->operands[i]);
 555                 this_walk_state->operands[i] = NULL;
 556         }
 557
 558         /* Clear the operand stack */
 559
 560         this_walk_state->num_operands = 0;
 561
 562         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 563                           "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",
 564                           method_node->name.ascii, next_walk_state));
 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 cleanup:
 579
 580         /* On error, we must terminate the method properly */
 581
 582         acpi_ds_terminate_control_method(obj_desc, next_walk_state);
 583         acpi_ds_delete_walk_state(next_walk_state);
 584
 585         return_ACPI_STATUS(status);
 586 }
 587
 588 /*******************************************************************************
 589  *
 590  * FUNCTION:    acpi_ds_restart_control_method
 591  *
 592  * PARAMETERS:  walk_state          - State for preempted method (caller)
 593  *              return_desc         - Return value from the called method
 594  *
 595  * RETURN:      Status
 596  *
 597  * DESCRIPTION: Restart a method that was preempted by another (nested) method
 598  *              invocation. Handle the return value (if any) from the callee.
 599  *
 600  ******************************************************************************/
 601
 602 acpi_status
 603 acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,
 604                                union acpi_operand_object *return_desc)
 605 {
 606         acpi_status status;
 607         int same_as_implicit_return;
 608
 609         ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);
 610
 611         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 612                           "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",
 613                           acpi_ut_get_node_name(walk_state->method_node),
 614                           walk_state->method_call_op, return_desc));
 615
 616         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 617                           "    ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",
 618                           walk_state->return_used,
 619                           walk_state->results, walk_state));
 620
 621         /* Did the called method return a value? */
 622
 623         if (return_desc) {
 624
 625                 /* Is the implicit return object the same as the return desc? */
 626
 627                 same_as_implicit_return =
 628                     (walk_state->implicit_return_obj == return_desc);
 629
 630                 /* Are we actually going to use the return value? */
 631
 632                 if (walk_state->return_used) {
 633
 634                         /* Save the return value from the previous method */
 635
 636                         status = acpi_ds_result_push(return_desc, walk_state);
 637                         if (ACPI_FAILURE(status)) {
 638                                 acpi_ut_remove_reference(return_desc);
 639                                 return_ACPI_STATUS(status);
 640                         }
 641
 642                         /*
 643                          * Save as THIS method's return value in case it is returned
 644                          * immediately to yet another method
 645                          */
 646                         walk_state->return_desc = return_desc;
 647                 }
 648
 649                 /*
 650                  * The following code is the optional support for the so-called
 651                  * "implicit return". Some AML code assumes that the last value of the
 652                  * method is "implicitly" returned to the caller, in the absence of an
 653                  * explicit return value.
 654                  *
 655                  * Just save the last result of the method as the return value.
 656                  *
 657                  * NOTE: this is optional because the ASL language does not actually
 658                  * support this behavior.
 659                  */
 660                 else if (!acpi_ds_do_implicit_return
 661                          (return_desc, walk_state, FALSE)
 662                          || same_as_implicit_return) {
 663                         /*
 664                          * Delete the return value if it will not be used by the
 665                          * calling method or remove one reference if the explicit return
 666                          * is the same as the implicit return value.
 667                          */
 668                         acpi_ut_remove_reference(return_desc);
 669                 }
 670         }
 671
 672         return_ACPI_STATUS(AE_OK);
 673 }
 674
 675 /*******************************************************************************
 676  *
 677  * FUNCTION:    acpi_ds_terminate_control_method
 678  *
 679  * PARAMETERS:  method_desc         - Method object
 680  *              walk_state          - State associated with the method
 681  *
 682  * RETURN:      None
 683  *
 684  * DESCRIPTION: Terminate a control method. Delete everything that the method
 685  *              created, delete all locals and arguments, and delete the parse
 686  *              tree if requested.
 687  *
 688  * MUTEX:       Interpreter is locked
 689  *
 690  ******************************************************************************/
 691
 692 void
 693 acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
 694                                  struct acpi_walk_state *walk_state)
 695 {
 696
 697         ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);
 698
 699         /* method_desc is required, walk_state is optional */
 700
 701         if (!method_desc) {
 702                 return_VOID;
 703         }
 704
 705         if (walk_state) {
 706
 707                 /* Delete all arguments and locals */
 708
 709                 acpi_ds_method_data_delete_all(walk_state);
 710
 711                 /*
 712                  * If method is serialized, release the mutex and restore the
 713                  * current sync level for this thread
 714                  */
 715                 if (method_desc->method.mutex) {
 716
 717                         /* Acquisition Depth handles recursive calls */
 718
 719                         method_desc->method.mutex->mutex.acquisition_depth--;
 720                         if (!method_desc->method.mutex->mutex.acquisition_depth) {
 721                                 walk_state->thread->current_sync_level =
 722                                     method_desc->method.mutex->mutex.
 723                                     original_sync_level;
 724
 725                                 acpi_os_release_mutex(method_desc->method.
 726                                                       mutex->mutex.os_mutex);
 727                                 method_desc->method.mutex->mutex.thread_id = 0;
 728                         }
 729                 }
 730
 731                 /*
 732                  * Delete any namespace objects created anywhere within the
 733                  * namespace by the execution of this method. Unless:
 734                  * 1) This method is a module-level executable code method, in which
 735                  *    case we want make the objects permanent.
 736                  * 2) There are other threads executing the method, in which case we
 737                  *    will wait until the last thread has completed.
 738                  */
 739                 if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)
 740                     && (method_desc->method.thread_count == 1)) {
 741
 742                         /* Delete any direct children of (created by) this method */
 743
 744                         acpi_ns_delete_namespace_subtree(walk_state->
 745                                                          method_node);
 746
 747                         /*
 748                          * Delete any objects that were created by this method
 749                          * elsewhere in the namespace (if any were created).
 750                          * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the
 751                          * deletion such that we don't have to perform an entire
 752                          * namespace walk for every control method execution.
 753                          */
 754                         if (method_desc->method.
 755                             info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {
 756                                 acpi_ns_delete_namespace_by_owner(method_desc->
 757                                                                   method.
 758                                                                   owner_id);
 759                                 method_desc->method.info_flags &=
 760                                     ~ACPI_METHOD_MODIFIED_NAMESPACE;
 761                         }
 762                 }
 763         }
 764
 765         /* Decrement the thread count on the method */
 766
 767         if (method_desc->method.thread_count) {
 768                 method_desc->method.thread_count--;
 769         } else {
 770                 ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));
 771         }
 772
 773         /* Are there any other threads currently executing this method? */
 774
 775         if (method_desc->method.thread_count) {
 776                 /*
 777                  * Additional threads. Do not release the owner_id in this case,
 778                  * we immediately reuse it for the next thread executing this method
 779                  */
 780                 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 781                                   "*** Completed execution of one thread, %u threads remaining\n",
 782                                   method_desc->method.thread_count));
 783         } else {
 784                 /* This is the only executing thread for this method */
 785
 786                 /*
 787                  * Support to dynamically change a method from not_serialized to
 788                  * Serialized if it appears that the method is incorrectly written and
 789                  * does not support multiple thread execution. The best example of this
 790                  * is if such a method creates namespace objects and blocks. A second
 791                  * thread will fail with an AE_ALREADY_EXISTS exception.
 792                  *
 793                  * This code is here because we must wait until the last thread exits
 794                  * before marking the method as serialized.
 795                  */
 796                 if (method_desc->method.
 797                     info_flags & ACPI_METHOD_SERIALIZED_PENDING) {
 798                         if (walk_state) {
 799                                 ACPI_INFO((AE_INFO,
 800                                            "Marking method %4.4s as Serialized because of AE_ALREADY_EXISTS error",
 801                                            walk_state->method_node->name.
 802                                            ascii));
 803                         }
 804
 805                         /*
 806                          * Method tried to create an object twice and was marked as
 807                          * "pending serialized". The probable cause is that the method
 808                          * cannot handle reentrancy.
 809                          *
 810                          * The method was created as not_serialized, but it tried to create
 811                          * a named object and then blocked, causing the second thread
 812                          * entrance to begin and then fail. Workaround this problem by
 813                          * marking the method permanently as Serialized when the last
 814                          * thread exits here.
 815                          */
 816                         method_desc->method.info_flags &=
 817                             ~ACPI_METHOD_SERIALIZED_PENDING;
 818                         method_desc->method.info_flags |=
 819                             (ACPI_METHOD_SERIALIZED |
 820                              ACPI_METHOD_IGNORE_SYNC_LEVEL);
 821                         method_desc->method.sync_level = 0;
 822                 }
 823
 824                 /* No more threads, we can free the owner_id */
 825
 826                 if (!
 827                     (method_desc->method.
 828                      info_flags & ACPI_METHOD_MODULE_LEVEL)) {
 829                         acpi_ut_release_owner_id(&method_desc->method.owner_id);
 830                 }
 831         }
 832
 833         acpi_ex_stop_trace_method((struct acpi_namespace_node *)method_desc->
 834                                   method.node, method_desc, walk_state);
 835
 836         return_VOID;
 837 }