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