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 - 2014, Intel Corp.
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions, and the following disclaimer,
  16  *    without modification.
  17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  18  *    substantially similar to the "NO WARRANTY" disclaimer below
  19  *    ("Disclaimer") and any redistribution must be conditioned upon
  20  *    including a substantially similar Disclaimer requirement for further
  21  *    binary redistribution.
  22  * 3. Neither the names of the above-listed copyright holders nor the names
  23  *    of any contributors may be used to endorse or promote products derived
  24  *    from this software without specific prior written permission.
  25  *
  26  * Alternatively, this software may be distributed under the terms of the
  27  * GNU General Public License ("GPL") version 2 as published by the Free
  28  * Software Foundation.
  29  *
  30  * NO WARRANTY
  31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  41  * POSSIBILITY OF SUCH DAMAGES.
  42  */
  43
  44 #include <acpi/acpi.h>
  45 #include "accommon.h"
  46 #include "acdispat.h"
  47 #include "acinterp.h"
  48 #include "acnamesp.h"
  49 #ifdef  ACPI_DISASSEMBLER
  50 #include "acdisasm.h"
  51 #endif
  52 #include "acparser.h"
  53 #include "amlcode.h"
  54
  55 #define _COMPONENT          ACPI_DISPATCHER
  56 ACPI_MODULE_NAME("dsmethod")
  57
  58 /* Local prototypes */
  59 static acpi_status
  60 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
  61                              union acpi_parse_object **out_op);
  62
  63 static acpi_status
  64 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc);
  65
  66 /*******************************************************************************
  67  *
  68  * FUNCTION:    acpi_ds_auto_serialize_method
  69  *
  70  * PARAMETERS:  node                        - Namespace Node of the method
  71  *              obj_desc                    - Method object attached to node
  72  *
  73  * RETURN:      Status
  74  *
  75  * DESCRIPTION: Parse a control method AML to scan for control methods that
  76  *              need serialization due to the creation of named objects.
  77  *
  78  * NOTE: It is a bit of overkill to mark all such methods serialized, since
  79  * there is only a problem if the method actually blocks during execution.
  80  * A blocking operation is, for example, a Sleep() operation, or any access
  81  * to an operation region. However, it is probably not possible to easily
  82  * detect whether a method will block or not, so we simply mark all suspicious
  83  * methods as serialized.
  84  *
  85  * NOTE2: This code is essentially a generic routine for parsing a single
  86  * control method.
  87  *
  88  ******************************************************************************/
  89
  90 acpi_status
  91 acpi_ds_auto_serialize_method(struct acpi_namespace_node *node,
  92                               union acpi_operand_object *obj_desc)
  93 {
  94         acpi_status status;
  95         union acpi_parse_object *op = NULL;
  96         struct acpi_walk_state *walk_state;
  97
  98         ACPI_FUNCTION_TRACE_PTR(ds_auto_serialize_method, node);
  99
 100         ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
 101                           "Method auto-serialization parse [%4.4s] %p\n",
 102                           acpi_ut_get_node_name(node), node));
 103
 104         /* Create/Init a root op for the method parse tree */
 105
 106         op = acpi_ps_alloc_op(AML_METHOD_OP);
 107         if (!op) {
 108                 return_ACPI_STATUS(AE_NO_MEMORY);
 109         }
 110
 111         acpi_ps_set_name(op, node->name.integer);
 112         op->common.node = node;
 113
 114         /* Create and initialize a new walk state */
 115
 116         walk_state =
 117             acpi_ds_create_walk_state(node->owner_id, NULL, NULL, NULL);
 118         if (!walk_state) {
 119                 return_ACPI_STATUS(AE_NO_MEMORY);
 120         }
 121
 122         status =
 123             acpi_ds_init_aml_walk(walk_state, op, node,
 124                                   obj_desc->method.aml_start,
 125                                   obj_desc->method.aml_length, NULL, 0);
 126         if (ACPI_FAILURE(status)) {
 127                 acpi_ds_delete_walk_state(walk_state);
 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         if (ACPI_FAILURE(status)) {
 137                 return_ACPI_STATUS(status);
 138         }
 139
 140         acpi_ps_delete_parse_tree(op);
 141         return_ACPI_STATUS(status);
 142 }
 143
 144 /*******************************************************************************
 145  *
 146  * FUNCTION:    acpi_ds_detect_named_opcodes
 147  *
 148  * PARAMETERS:  walk_state      - Current state of the parse tree walk
 149  *              out_op          - Unused, required for parser interface
 150  *
 151  * RETURN:      Status
 152  *
 153  * DESCRIPTION: Descending callback used during the loading of ACPI tables.
 154  *              Currently used to detect methods that must be marked serialized
 155  *              in order to avoid problems with the creation of named objects.
 156  *
 157  ******************************************************************************/
 158
 159 static acpi_status
 160 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
 161                              union acpi_parse_object **out_op)
 162 {
 163
 164         ACPI_FUNCTION_NAME(acpi_ds_detect_named_opcodes);
 165
 166         /* We are only interested in opcodes that create a new name */
 167
 168         if (!
 169             (walk_state->op_info->
 170              flags & (AML_NAMED | AML_CREATE | AML_FIELD))) {
 171                 return (AE_OK);
 172         }
 173
 174         /*
 175          * At this point, we know we have a Named object opcode.
 176          * Mark the method as serialized. Later code will create a mutex for
 177          * this method to enforce serialization.
 178          */
 179         walk_state->method_desc->method.info_flags |= ACPI_METHOD_SERIALIZED;
 180
 181         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 182                           "Method serialized [%4.4s] %p - [%s] (%4.4X)\n",
 183                           walk_state->method_node->name.ascii,
 184                           walk_state->method_node, walk_state->op_info->name,
 185                           walk_state->opcode));
 186
 187         /* Abort the parse, no need to examine this method any further */
 188
 189         return (AE_CTRL_TERMINATE);
 190 }
 191
 192 /*******************************************************************************
 193  *
 194  * FUNCTION:    acpi_ds_method_error
 195  *
 196  * PARAMETERS:  status          - Execution status
 197  *              walk_state      - Current state
 198  *
 199  * RETURN:      Status
 200  *
 201  * DESCRIPTION: Called on method error. Invoke the global exception handler if
 202  *              present, dump the method data if the disassembler is configured
 203  *
 204  *              Note: Allows the exception handler to change the status code
 205  *
 206  ******************************************************************************/
 207
 208 acpi_status
 209 acpi_ds_method_error(acpi_status status, struct acpi_walk_state * walk_state)
 210 {
 211         ACPI_FUNCTION_ENTRY();
 212
 213         /* Ignore AE_OK and control exception codes */
 214
 215         if (ACPI_SUCCESS(status) || (status & AE_CODE_CONTROL)) {
 216                 return (status);
 217         }
 218
 219         /* Invoke the global exception handler */
 220
 221         if (acpi_gbl_exception_handler) {
 222
 223                 /* Exit the interpreter, allow handler to execute methods */
 224
 225                 acpi_ex_exit_interpreter();
 226
 227                 /*
 228                  * Handler can map the exception code to anything it wants, including
 229                  * AE_OK, in which case the executing method will not be aborted.
 230                  */
 231                 status = acpi_gbl_exception_handler(status,
 232                                                     walk_state->method_node ?
 233                                                     walk_state->method_node->
 234                                                     name.integer : 0,
 235                                                     walk_state->opcode,
 236                                                     walk_state->aml_offset,
 237                                                     NULL);
 238                 acpi_ex_enter_interpreter();
 239         }
 240
 241         acpi_ds_clear_implicit_return(walk_state);
 242
 243 #ifdef ACPI_DISASSEMBLER
 244         if (ACPI_FAILURE(status)) {
 245
 246                 /* Display method locals/args if disassembler is present */
 247
 248                 acpi_dm_dump_method_info(status, walk_state, walk_state->op);
 249         }
 250 #endif
 251
 252         return (status);
 253 }
 254
 255 /*******************************************************************************
 256  *
 257  * FUNCTION:    acpi_ds_create_method_mutex
 258  *
 259  * PARAMETERS:  obj_desc            - The method object
 260  *
 261  * RETURN:      Status
 262  *
 263  * DESCRIPTION: Create a mutex object for a serialized control method
 264  *
 265  ******************************************************************************/
 266
 267 static acpi_status
 268 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc)
 269 {
 270         union acpi_operand_object *mutex_desc;
 271         acpi_status status;
 272
 273         ACPI_FUNCTION_TRACE(ds_create_method_mutex);
 274
 275         /* Create the new mutex object */
 276
 277         mutex_desc = acpi_ut_create_internal_object(ACPI_TYPE_MUTEX);
 278         if (!mutex_desc) {
 279                 return_ACPI_STATUS(AE_NO_MEMORY);
 280         }
 281
 282         /* Create the actual OS Mutex */
 283
 284         status = acpi_os_create_mutex(&mutex_desc->mutex.os_mutex);
 285         if (ACPI_FAILURE(status)) {
 286                 acpi_ut_delete_object_desc(mutex_desc);
 287                 return_ACPI_STATUS(status);
 288         }
 289
 290         mutex_desc->mutex.sync_level = method_desc->method.sync_level;
 291         method_desc->method.mutex = mutex_desc;
 292         return_ACPI_STATUS(AE_OK);
 293 }
 294
 295 /*******************************************************************************
 296  *
 297  * FUNCTION:    acpi_ds_begin_method_execution
 298  *
 299  * PARAMETERS:  method_node         - Node of the method
 300  *              obj_desc            - The method object
 301  *              walk_state          - current state, NULL if not yet executing
 302  *                                    a method.
 303  *
 304  * RETURN:      Status
 305  *
 306  * DESCRIPTION: Prepare a method for execution. Parses the method if necessary,
 307  *              increments the thread count, and waits at the method semaphore
 308  *              for clearance to execute.
 309  *
 310  ******************************************************************************/
 311
 312 acpi_status
 313 acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
 314                                union acpi_operand_object *obj_desc,
 315                                struct acpi_walk_state *walk_state)
 316 {
 317         acpi_status status = AE_OK;
 318
 319         ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);
 320
 321         if (!method_node) {
 322                 return_ACPI_STATUS(AE_NULL_ENTRY);
 323         }
 324
 325         /* Prevent wraparound of thread count */
 326
 327         if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {
 328                 ACPI_ERROR((AE_INFO,
 329                             "Method reached maximum reentrancy limit (255)"));
 330                 return_ACPI_STATUS(AE_AML_METHOD_LIMIT);
 331         }
 332
 333         /*
 334          * If this method is serialized, we need to acquire the method mutex.
 335          */
 336         if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {
 337                 /*
 338                  * Create a mutex for the method if it is defined to be Serialized
 339                  * and a mutex has not already been created. We defer the mutex creation
 340                  * until a method is actually executed, to minimize the object count
 341                  */
 342                 if (!obj_desc->method.mutex) {
 343                         status = acpi_ds_create_method_mutex(obj_desc);
 344                         if (ACPI_FAILURE(status)) {
 345                                 return_ACPI_STATUS(status);
 346                         }
 347                 }
 348
 349                 /*
 350                  * The current_sync_level (per-thread) must be less than or equal to
 351                  * the sync level of the method. This mechanism provides some
 352                  * deadlock prevention
 353                  *
 354                  * Top-level method invocation has no walk state at this point
 355                  */
 356                 if (walk_state &&
 357                     (walk_state->thread->current_sync_level >
 358                      obj_desc->method.mutex->mutex.sync_level)) {
 359                         ACPI_ERROR((AE_INFO,
 360                                     "Cannot acquire Mutex for method [%4.4s], current SyncLevel is too large (%u)",
 361                                     acpi_ut_get_node_name(method_node),
 362                                     walk_state->thread->current_sync_level));
 363
 364                         return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
 365                 }
 366
 367                 /*
 368                  * Obtain the method mutex if necessary. Do not acquire mutex for a
 369                  * recursive call.
 370                  */
 371                 if (!walk_state ||
 372                     !obj_desc->method.mutex->mutex.thread_id ||
 373                     (walk_state->thread->thread_id !=
 374                      obj_desc->method.mutex->mutex.thread_id)) {
 375                         /*
 376                          * Acquire the method mutex. This releases the interpreter if we
 377                          * block (and reacquires it before it returns)
 378                          */
 379                         status =
 380                             acpi_ex_system_wait_mutex(obj_desc->method.mutex->
 381                                                       mutex.os_mutex,
 382                                                       ACPI_WAIT_FOREVER);
 383                         if (ACPI_FAILURE(status)) {
 384                                 return_ACPI_STATUS(status);
 385                         }
 386
 387                         /* Update the mutex and walk info and save the original sync_level */
 388
 389                         if (walk_state) {
 390                                 obj_desc->method.mutex->mutex.
 391                                     original_sync_level =
 392                                     walk_state->thread->current_sync_level;
 393
 394                                 obj_desc->method.mutex->mutex.thread_id =
 395                                     walk_state->thread->thread_id;
 396                                 walk_state->thread->current_sync_level =
 397                                     obj_desc->method.sync_level;
 398                         } else {
 399                                 obj_desc->method.mutex->mutex.
 400                                     original_sync_level =
 401                                     obj_desc->method.mutex->mutex.sync_level;
 402                         }
 403                 }
 404
 405                 /* Always increase acquisition depth */
 406
 407                 obj_desc->method.mutex->mutex.acquisition_depth++;
 408         }
 409
 410         /*
 411          * Allocate an Owner ID for this method, only if this is the first thread
 412          * to begin concurrent execution. We only need one owner_id, even if the
 413          * method is invoked recursively.
 414          */
 415         if (!obj_desc->method.owner_id) {
 416                 status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);
 417                 if (ACPI_FAILURE(status)) {
 418                         goto cleanup;
 419                 }
 420         }
 421
 422         /*
 423          * Increment the method parse tree thread count since it has been
 424          * reentered one more time (even if it is the same thread)
 425          */
 426         obj_desc->method.thread_count++;
 427         acpi_method_count++;
 428         return_ACPI_STATUS(status);
 429
 430 cleanup:
 431         /* On error, must release the method mutex (if present) */
 432
 433         if (obj_desc->method.mutex) {
 434                 acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);
 435         }
 436         return_ACPI_STATUS(status);
 437 }
 438
 439 /*******************************************************************************
 440  *
 441  * FUNCTION:    acpi_ds_call_control_method
 442  *
 443  * PARAMETERS:  thread              - Info for this thread
 444  *              this_walk_state     - Current walk state
 445  *              op                  - Current Op to be walked
 446  *
 447  * RETURN:      Status
 448  *
 449  * DESCRIPTION: Transfer execution to a called control method
 450  *
 451  ******************************************************************************/
 452
 453 acpi_status
 454 acpi_ds_call_control_method(struct acpi_thread_state *thread,
 455                             struct acpi_walk_state *this_walk_state,
 456                             union acpi_parse_object *op)
 457 {
 458         acpi_status status;
 459         struct acpi_namespace_node *method_node;
 460         struct acpi_walk_state *next_walk_state = NULL;
 461         union acpi_operand_object *obj_desc;
 462         struct acpi_evaluate_info *info;
 463         u32 i;
 464
 465         ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);
 466
 467         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 468                           "Calling method %p, currentstate=%p\n",
 469                           this_walk_state->prev_op, this_walk_state));
 470
 471         /*
 472          * Get the namespace entry for the control method we are about to call
 473          */
 474         method_node = this_walk_state->method_call_node;
 475         if (!method_node) {
 476                 return_ACPI_STATUS(AE_NULL_ENTRY);
 477         }
 478
 479         obj_desc = acpi_ns_get_attached_object(method_node);
 480         if (!obj_desc) {
 481                 return_ACPI_STATUS(AE_NULL_OBJECT);
 482         }
 483
 484         /* Init for new method, possibly wait on method mutex */
 485
 486         status = acpi_ds_begin_method_execution(method_node, obj_desc,
 487                                                 this_walk_state);
 488         if (ACPI_FAILURE(status)) {
 489                 return_ACPI_STATUS(status);
 490         }
 491
 492         /* Begin method parse/execution. Create a new walk state */
 493
 494         next_walk_state = acpi_ds_create_walk_state(obj_desc->method.owner_id,
 495                                                     NULL, obj_desc, thread);
 496         if (!next_walk_state) {
 497                 status = AE_NO_MEMORY;
 498                 goto cleanup;
 499         }
 500
 501         /*
 502          * The resolved arguments were put on the previous walk state's operand
 503          * stack. Operands on the previous walk state stack always
 504          * start at index 0. Also, null terminate the list of arguments
 505          */
 506         this_walk_state->operands[this_walk_state->num_operands] = NULL;
 507
 508         /*
 509          * Allocate and initialize the evaluation information block
 510          * TBD: this is somewhat inefficient, should change interface to
 511          * ds_init_aml_walk. For now, keeps this struct off the CPU stack
 512          */
 513         info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
 514         if (!info) {
 515                 status = AE_NO_MEMORY;
 516                 goto cleanup;
 517         }
 518
 519         info->parameters = &this_walk_state->operands[0];
 520
 521         status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,
 522                                        obj_desc->method.aml_start,
 523                                        obj_desc->method.aml_length, info,
 524                                        ACPI_IMODE_EXECUTE);
 525
 526         ACPI_FREE(info);
 527         if (ACPI_FAILURE(status)) {
 528                 goto cleanup;
 529         }
 530
 531         /*
 532          * Delete the operands on the previous walkstate operand stack
 533          * (they were copied to new objects)
 534          */
 535         for (i = 0; i < obj_desc->method.param_count; i++) {
 536                 acpi_ut_remove_reference(this_walk_state->operands[i]);
 537                 this_walk_state->operands[i] = NULL;
 538         }
 539
 540         /* Clear the operand stack */
 541
 542         this_walk_state->num_operands = 0;
 543
 544         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 545                           "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",
 546                           method_node->name.ascii, next_walk_state));
 547
 548         /* Invoke an internal method if necessary */
 549
 550         if (obj_desc->method.info_flags & ACPI_METHOD_INTERNAL_ONLY) {
 551                 status =
 552                     obj_desc->method.dispatch.implementation(next_walk_state);
 553                 if (status == AE_OK) {
 554                         status = AE_CTRL_TERMINATE;
 555                 }
 556         }
 557
 558         return_ACPI_STATUS(status);
 559
 560 cleanup:
 561
 562         /* On error, we must terminate the method properly */
 563
 564         acpi_ds_terminate_control_method(obj_desc, next_walk_state);
 565         if (next_walk_state) {
 566                 acpi_ds_delete_walk_state(next_walk_state);
 567         }
 568
 569         return_ACPI_STATUS(status);
 570 }
 571
 572 /*******************************************************************************
 573  *
 574  * FUNCTION:    acpi_ds_restart_control_method
 575  *
 576  * PARAMETERS:  walk_state          - State for preempted method (caller)
 577  *              return_desc         - Return value from the called method
 578  *
 579  * RETURN:      Status
 580  *
 581  * DESCRIPTION: Restart a method that was preempted by another (nested) method
 582  *              invocation. Handle the return value (if any) from the callee.
 583  *
 584  ******************************************************************************/
 585
 586 acpi_status
 587 acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,
 588                                union acpi_operand_object *return_desc)
 589 {
 590         acpi_status status;
 591         int same_as_implicit_return;
 592
 593         ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);
 594
 595         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 596                           "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",
 597                           acpi_ut_get_node_name(walk_state->method_node),
 598                           walk_state->method_call_op, return_desc));
 599
 600         ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 601                           "    ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",
 602                           walk_state->return_used,
 603                           walk_state->results, walk_state));
 604
 605         /* Did the called method return a value? */
 606
 607         if (return_desc) {
 608
 609                 /* Is the implicit return object the same as the return desc? */
 610
 611                 same_as_implicit_return =
 612                     (walk_state->implicit_return_obj == return_desc);
 613
 614                 /* Are we actually going to use the return value? */
 615
 616                 if (walk_state->return_used) {
 617
 618                         /* Save the return value from the previous method */
 619
 620                         status = acpi_ds_result_push(return_desc, walk_state);
 621                         if (ACPI_FAILURE(status)) {
 622                                 acpi_ut_remove_reference(return_desc);
 623                                 return_ACPI_STATUS(status);
 624                         }
 625
 626                         /*
 627                          * Save as THIS method's return value in case it is returned
 628                          * immediately to yet another method
 629                          */
 630                         walk_state->return_desc = return_desc;
 631                 }
 632
 633                 /*
 634                  * The following code is the optional support for the so-called
 635                  * "implicit return". Some AML code assumes that the last value of the
 636                  * method is "implicitly" returned to the caller, in the absence of an
 637                  * explicit return value.
 638                  *
 639                  * Just save the last result of the method as the return value.
 640                  *
 641                  * NOTE: this is optional because the ASL language does not actually
 642                  * support this behavior.
 643                  */
 644                 else if (!acpi_ds_do_implicit_return
 645                          (return_desc, walk_state, FALSE)
 646                          || same_as_implicit_return) {
 647                         /*
 648                          * Delete the return value if it will not be used by the
 649                          * calling method or remove one reference if the explicit return
 650                          * is the same as the implicit return value.
 651                          */
 652                         acpi_ut_remove_reference(return_desc);
 653                 }
 654         }
 655
 656         return_ACPI_STATUS(AE_OK);
 657 }
 658
 659 /*******************************************************************************
 660  *
 661  * FUNCTION:    acpi_ds_terminate_control_method
 662  *
 663  * PARAMETERS:  method_desc         - Method object
 664  *              walk_state          - State associated with the method
 665  *
 666  * RETURN:      None
 667  *
 668  * DESCRIPTION: Terminate a control method. Delete everything that the method
 669  *              created, delete all locals and arguments, and delete the parse
 670  *              tree if requested.
 671  *
 672  * MUTEX:       Interpreter is locked
 673  *
 674  ******************************************************************************/
 675
 676 void
 677 acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
 678                                  struct acpi_walk_state *walk_state)
 679 {
 680
 681         ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);
 682
 683         /* method_desc is required, walk_state is optional */
 684
 685         if (!method_desc) {
 686                 return_VOID;
 687         }
 688
 689         if (walk_state) {
 690
 691                 /* Delete all arguments and locals */
 692
 693                 acpi_ds_method_data_delete_all(walk_state);
 694
 695                 /*
 696                  * If method is serialized, release the mutex and restore the
 697                  * current sync level for this thread
 698                  */
 699                 if (method_desc->method.mutex) {
 700
 701                         /* Acquisition Depth handles recursive calls */
 702
 703                         method_desc->method.mutex->mutex.acquisition_depth--;
 704                         if (!method_desc->method.mutex->mutex.acquisition_depth) {
 705                                 walk_state->thread->current_sync_level =
 706                                     method_desc->method.mutex->mutex.
 707                                     original_sync_level;
 708
 709                                 acpi_os_release_mutex(method_desc->method.
 710                                                       mutex->mutex.os_mutex);
 711                                 method_desc->method.mutex->mutex.thread_id = 0;
 712                         }
 713                 }
 714
 715                 /*
 716                  * Delete any namespace objects created anywhere within the
 717                  * namespace by the execution of this method. Unless:
 718                  * 1) This method is a module-level executable code method, in which
 719                  *    case we want make the objects permanent.
 720                  * 2) There are other threads executing the method, in which case we
 721                  *    will wait until the last thread has completed.
 722                  */
 723                 if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)
 724                     && (method_desc->method.thread_count == 1)) {
 725
 726                         /* Delete any direct children of (created by) this method */
 727
 728                         acpi_ns_delete_namespace_subtree(walk_state->
 729                                                          method_node);
 730
 731                         /*
 732                          * Delete any objects that were created by this method
 733                          * elsewhere in the namespace (if any were created).
 734                          * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the
 735                          * deletion such that we don't have to perform an entire
 736                          * namespace walk for every control method execution.
 737                          */
 738                         if (method_desc->method.
 739                             info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {
 740                                 acpi_ns_delete_namespace_by_owner(method_desc->
 741                                                                   method.
 742                                                                   owner_id);
 743                                 method_desc->method.info_flags &=
 744                                     ~ACPI_METHOD_MODIFIED_NAMESPACE;
 745                         }
 746                 }
 747         }
 748
 749         /* Decrement the thread count on the method */
 750
 751         if (method_desc->method.thread_count) {
 752                 method_desc->method.thread_count--;
 753         } else {
 754                 ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));
 755         }
 756
 757         /* Are there any other threads currently executing this method? */
 758
 759         if (method_desc->method.thread_count) {
 760                 /*
 761                  * Additional threads. Do not release the owner_id in this case,
 762                  * we immediately reuse it for the next thread executing this method
 763                  */
 764                 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 765                                   "*** Completed execution of one thread, %u threads remaining\n",
 766                                   method_desc->method.thread_count));
 767         } else {
 768                 /* This is the only executing thread for this method */
 769
 770                 /*
 771                  * Support to dynamically change a method from not_serialized to
 772                  * Serialized if it appears that the method is incorrectly written and
 773                  * does not support multiple thread execution. The best example of this
 774                  * is if such a method creates namespace objects and blocks. A second
 775                  * thread will fail with an AE_ALREADY_EXISTS exception.
 776                  *
 777                  * This code is here because we must wait until the last thread exits
 778                  * before marking the method as serialized.
 779                  */
 780                 if (method_desc->method.
 781                     info_flags & ACPI_METHOD_SERIALIZED_PENDING) {
 782                         if (walk_state) {
 783                                 ACPI_INFO((AE_INFO,
 784                                            "Marking method %4.4s as Serialized because of AE_ALREADY_EXISTS error",
 785                                            walk_state->method_node->name.
 786                                            ascii));
 787                         }
 788
 789                         /*
 790                          * Method tried to create an object twice and was marked as
 791                          * "pending serialized". The probable cause is that the method
 792                          * cannot handle reentrancy.
 793                          *
 794                          * The method was created as not_serialized, but it tried to create
 795                          * a named object and then blocked, causing the second thread
 796                          * entrance to begin and then fail. Workaround this problem by
 797                          * marking the method permanently as Serialized when the last
 798                          * thread exits here.
 799                          */
 800                         method_desc->method.info_flags &=
 801                             ~ACPI_METHOD_SERIALIZED_PENDING;
 802                         method_desc->method.info_flags |=
 803                             ACPI_METHOD_SERIALIZED;
 804                         method_desc->method.sync_level = 0;
 805                 }
 806
 807                 /* No more threads, we can free the owner_id */
 808
 809                 if (!
 810                     (method_desc->method.
 811                      info_flags & ACPI_METHOD_MODULE_LEVEL)) {
 812                         acpi_ut_release_owner_id(&method_desc->method.owner_id);
 813                 }
 814         }
 815
 816         return_VOID;
 817 }