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