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1// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.02/******************************************************************************3 *4 * Module Name: dsmethod - Parser/Interpreter interface - control method parsing5 *6 * Copyright (C) 2000 - 2023, Intel Corp.7 *8 *****************************************************************************/9 10#include <acpi/acpi.h>11#include "accommon.h"12#include "acdispat.h"13#include "acinterp.h"14#include "acnamesp.h"15#include "acparser.h"16#include "amlcode.h"17#include "acdebug.h"18 19#define _COMPONENT ACPI_DISPATCHER20ACPI_MODULE_NAME("dsmethod")21 22/* Local prototypes */23static acpi_status24acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,25 union acpi_parse_object **out_op);26 27static acpi_status28acpi_ds_create_method_mutex(union acpi_operand_object *method_desc);29 30/*******************************************************************************31 *32 * FUNCTION: acpi_ds_auto_serialize_method33 *34 * PARAMETERS: node - Namespace Node of the method35 * obj_desc - Method object attached to node36 *37 * RETURN: Status38 *39 * DESCRIPTION: Parse a control method AML to scan for control methods that40 * need serialization due to the creation of named objects.41 *42 * NOTE: It is a bit of overkill to mark all such methods serialized, since43 * there is only a problem if the method actually blocks during execution.44 * A blocking operation is, for example, a Sleep() operation, or any access45 * to an operation region. However, it is probably not possible to easily46 * detect whether a method will block or not, so we simply mark all suspicious47 * methods as serialized.48 *49 * NOTE2: This code is essentially a generic routine for parsing a single50 * control method.51 *52 ******************************************************************************/53 54acpi_status55acpi_ds_auto_serialize_method(struct acpi_namespace_node *node,56 union acpi_operand_object *obj_desc)57{58 acpi_status status;59 union acpi_parse_object *op = NULL;60 struct acpi_walk_state *walk_state;61 62 ACPI_FUNCTION_TRACE_PTR(ds_auto_serialize_method, node);63 64 ACPI_DEBUG_PRINT((ACPI_DB_PARSE,65 "Method auto-serialization parse [%4.4s] %p\n",66 acpi_ut_get_node_name(node), node));67 68 /* Create/Init a root op for the method parse tree */69 70 op = acpi_ps_alloc_op(AML_METHOD_OP, obj_desc->method.aml_start);71 if (!op) {72 return_ACPI_STATUS(AE_NO_MEMORY);73 }74 75 acpi_ps_set_name(op, node->name.integer);76 op->common.node = node;77 78 /* Create and initialize a new walk state */79 80 walk_state =81 acpi_ds_create_walk_state(node->owner_id, NULL, NULL, NULL);82 if (!walk_state) {83 acpi_ps_free_op(op);84 return_ACPI_STATUS(AE_NO_MEMORY);85 }86 87 status = acpi_ds_init_aml_walk(walk_state, op, node,88 obj_desc->method.aml_start,89 obj_desc->method.aml_length, NULL, 0);90 if (ACPI_FAILURE(status)) {91 acpi_ds_delete_walk_state(walk_state);92 acpi_ps_free_op(op);93 return_ACPI_STATUS(status);94 }95 96 walk_state->descending_callback = acpi_ds_detect_named_opcodes;97 98 /* Parse the method, scan for creation of named objects */99 100 status = acpi_ps_parse_aml(walk_state);101 102 acpi_ps_delete_parse_tree(op);103 return_ACPI_STATUS(status);104}105 106/*******************************************************************************107 *108 * FUNCTION: acpi_ds_detect_named_opcodes109 *110 * PARAMETERS: walk_state - Current state of the parse tree walk111 * out_op - Unused, required for parser interface112 *113 * RETURN: Status114 *115 * DESCRIPTION: Descending callback used during the loading of ACPI tables.116 * Currently used to detect methods that must be marked serialized117 * in order to avoid problems with the creation of named objects.118 *119 ******************************************************************************/120 121static acpi_status122acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,123 union acpi_parse_object **out_op)124{125 126 ACPI_FUNCTION_NAME(acpi_ds_detect_named_opcodes);127 128 /* We are only interested in opcodes that create a new name */129 130 if (!131 (walk_state->op_info->132 flags & (AML_NAMED | AML_CREATE | AML_FIELD))) {133 return (AE_OK);134 }135 136 /*137 * At this point, we know we have a Named object opcode.138 * Mark the method as serialized. Later code will create a mutex for139 * this method to enforce serialization.140 *141 * Note, ACPI_METHOD_IGNORE_SYNC_LEVEL flag means that we will ignore the142 * Sync Level mechanism for this method, even though it is now serialized.143 * Otherwise, there can be conflicts with existing ASL code that actually144 * uses sync levels.145 */146 walk_state->method_desc->method.sync_level = 0;147 walk_state->method_desc->method.info_flags |=148 (ACPI_METHOD_SERIALIZED | ACPI_METHOD_IGNORE_SYNC_LEVEL);149 150 ACPI_DEBUG_PRINT((ACPI_DB_INFO,151 "Method serialized [%4.4s] %p - [%s] (%4.4X)\n",152 walk_state->method_node->name.ascii,153 walk_state->method_node, walk_state->op_info->name,154 walk_state->opcode));155 156 /* Abort the parse, no need to examine this method any further */157 158 return (AE_CTRL_TERMINATE);159}160 161/*******************************************************************************162 *163 * FUNCTION: acpi_ds_method_error164 *165 * PARAMETERS: status - Execution status166 * walk_state - Current state167 *168 * RETURN: Status169 *170 * DESCRIPTION: Called on method error. Invoke the global exception handler if171 * present, dump the method data if the debugger is configured172 *173 * Note: Allows the exception handler to change the status code174 *175 ******************************************************************************/176 177acpi_status178acpi_ds_method_error(acpi_status status, struct acpi_walk_state *walk_state)179{180 u32 aml_offset;181 acpi_name name = 0;182 183 ACPI_FUNCTION_ENTRY();184 185 /* Ignore AE_OK and control exception codes */186 187 if (ACPI_SUCCESS(status) || (status & AE_CODE_CONTROL)) {188 return (status);189 }190 191 /* Invoke the global exception handler */192 193 if (acpi_gbl_exception_handler) {194 195 /* Exit the interpreter, allow handler to execute methods */196 197 acpi_ex_exit_interpreter();198 199 /*200 * Handler can map the exception code to anything it wants, including201 * AE_OK, in which case the executing method will not be aborted.202 */203 aml_offset = (u32)ACPI_PTR_DIFF(walk_state->aml,204 walk_state->parser_state.205 aml_start);206 207 if (walk_state->method_node) {208 name = walk_state->method_node->name.integer;209 } else if (walk_state->deferred_node) {210 name = walk_state->deferred_node->name.integer;211 }212 213 status = acpi_gbl_exception_handler(status, name,214 walk_state->opcode,215 aml_offset, NULL);216 acpi_ex_enter_interpreter();217 }218 219 acpi_ds_clear_implicit_return(walk_state);220 221 if (ACPI_FAILURE(status)) {222 acpi_ds_dump_method_stack(status, walk_state, walk_state->op);223 224 /* Display method locals/args if debugger is present */225 226#ifdef ACPI_DEBUGGER227 acpi_db_dump_method_info(status, walk_state);228#endif229 }230 231 return (status);232}233 234/*******************************************************************************235 *236 * FUNCTION: acpi_ds_create_method_mutex237 *238 * PARAMETERS: obj_desc - The method object239 *240 * RETURN: Status241 *242 * DESCRIPTION: Create a mutex object for a serialized control method243 *244 ******************************************************************************/245 246static acpi_status247acpi_ds_create_method_mutex(union acpi_operand_object *method_desc)248{249 union acpi_operand_object *mutex_desc;250 acpi_status status;251 252 ACPI_FUNCTION_TRACE(ds_create_method_mutex);253 254 /* Create the new mutex object */255 256 mutex_desc = acpi_ut_create_internal_object(ACPI_TYPE_MUTEX);257 if (!mutex_desc) {258 return_ACPI_STATUS(AE_NO_MEMORY);259 }260 261 /* Create the actual OS Mutex */262 263 status = acpi_os_create_mutex(&mutex_desc->mutex.os_mutex);264 if (ACPI_FAILURE(status)) {265 acpi_ut_delete_object_desc(mutex_desc);266 return_ACPI_STATUS(status);267 }268 269 mutex_desc->mutex.sync_level = method_desc->method.sync_level;270 method_desc->method.mutex = mutex_desc;271 return_ACPI_STATUS(AE_OK);272}273 274/*******************************************************************************275 *276 * FUNCTION: acpi_ds_begin_method_execution277 *278 * PARAMETERS: method_node - Node of the method279 * obj_desc - The method object280 * walk_state - current state, NULL if not yet executing281 * a method.282 *283 * RETURN: Status284 *285 * DESCRIPTION: Prepare a method for execution. Parses the method if necessary,286 * increments the thread count, and waits at the method semaphore287 * for clearance to execute.288 *289 ******************************************************************************/290 291acpi_status292acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,293 union acpi_operand_object *obj_desc,294 struct acpi_walk_state *walk_state)295{296 acpi_status status = AE_OK;297 298 ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);299 300 if (!method_node) {301 return_ACPI_STATUS(AE_NULL_ENTRY);302 }303 304 acpi_ex_start_trace_method(method_node, obj_desc, walk_state);305 306 /* Prevent wraparound of thread count */307 308 if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {309 ACPI_ERROR((AE_INFO,310 "Method reached maximum reentrancy limit (255)"));311 return_ACPI_STATUS(AE_AML_METHOD_LIMIT);312 }313 314 /*315 * If this method is serialized, we need to acquire the method mutex.316 */317 if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {318 /*319 * Create a mutex for the method if it is defined to be Serialized320 * and a mutex has not already been created. We defer the mutex creation321 * until a method is actually executed, to minimize the object count322 */323 if (!obj_desc->method.mutex) {324 status = acpi_ds_create_method_mutex(obj_desc);325 if (ACPI_FAILURE(status)) {326 return_ACPI_STATUS(status);327 }328 }329 330 /*331 * The current_sync_level (per-thread) must be less than or equal to332 * the sync level of the method. This mechanism provides some333 * deadlock prevention.334 *335 * If the method was auto-serialized, we just ignore the sync level336 * mechanism, because auto-serialization of methods can interfere337 * with ASL code that actually uses sync levels.338 *339 * Top-level method invocation has no walk state at this point340 */341 if (walk_state &&342 (!(obj_desc->method.343 info_flags & ACPI_METHOD_IGNORE_SYNC_LEVEL))344 && (walk_state->thread->current_sync_level >345 obj_desc->method.mutex->mutex.sync_level)) {346 ACPI_ERROR((AE_INFO,347 "Cannot acquire Mutex for method [%4.4s]"348 ", current SyncLevel is too large (%u)",349 acpi_ut_get_node_name(method_node),350 walk_state->thread->current_sync_level));351 352 return_ACPI_STATUS(AE_AML_MUTEX_ORDER);353 }354 355 /*356 * Obtain the method mutex if necessary. Do not acquire mutex for a357 * recursive call.358 */359 if (!walk_state ||360 !obj_desc->method.mutex->mutex.thread_id ||361 (walk_state->thread->thread_id !=362 obj_desc->method.mutex->mutex.thread_id)) {363 /*364 * Acquire the method mutex. This releases the interpreter if we365 * block (and reacquires it before it returns)366 */367 status =368 acpi_ex_system_wait_mutex(obj_desc->method.mutex->369 mutex.os_mutex,370 ACPI_WAIT_FOREVER);371 if (ACPI_FAILURE(status)) {372 return_ACPI_STATUS(status);373 }374 375 /* Update the mutex and walk info and save the original sync_level */376 377 if (walk_state) {378 obj_desc->method.mutex->mutex.379 original_sync_level =380 walk_state->thread->current_sync_level;381 382 obj_desc->method.mutex->mutex.thread_id =383 walk_state->thread->thread_id;384 385 /*386 * Update the current sync_level only if this is not an auto-387 * serialized method. In the auto case, we have to ignore388 * the sync level for the method mutex (created for the389 * auto-serialization) because we have no idea of what the390 * sync level should be. Therefore, just ignore it.391 */392 if (!(obj_desc->method.info_flags &393 ACPI_METHOD_IGNORE_SYNC_LEVEL)) {394 walk_state->thread->current_sync_level =395 obj_desc->method.sync_level;396 }397 } else {398 obj_desc->method.mutex->mutex.399 original_sync_level =400 obj_desc->method.mutex->mutex.sync_level;401 402 obj_desc->method.mutex->mutex.thread_id =403 acpi_os_get_thread_id();404 }405 }406 407 /* Always increase acquisition depth */408 409 obj_desc->method.mutex->mutex.acquisition_depth++;410 }411 412 /*413 * Allocate an Owner ID for this method, only if this is the first thread414 * to begin concurrent execution. We only need one owner_id, even if the415 * method is invoked recursively.416 */417 if (!obj_desc->method.owner_id) {418 status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);419 if (ACPI_FAILURE(status)) {420 goto cleanup;421 }422 }423 424 /*425 * Increment the method parse tree thread count since it has been426 * reentered one more time (even if it is the same thread)427 */428 obj_desc->method.thread_count++;429 acpi_method_count++;430 return_ACPI_STATUS(status);431 432cleanup:433 /* On error, must release the method mutex (if present) */434 435 if (obj_desc->method.mutex) {436 acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);437 }438 return_ACPI_STATUS(status);439}440 441/*******************************************************************************442 *443 * FUNCTION: acpi_ds_call_control_method444 *445 * PARAMETERS: thread - Info for this thread446 * this_walk_state - Current walk state447 * op - Current Op to be walked448 *449 * RETURN: Status450 *451 * DESCRIPTION: Transfer execution to a called control method452 *453 ******************************************************************************/454 455acpi_status456acpi_ds_call_control_method(struct acpi_thread_state *thread,457 struct acpi_walk_state *this_walk_state,458 union acpi_parse_object *op)459{460 acpi_status status;461 struct acpi_namespace_node *method_node;462 struct acpi_walk_state *next_walk_state = NULL;463 union acpi_operand_object *obj_desc;464 struct acpi_evaluate_info *info;465 u32 i;466 467 ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);468 469 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,470 "Calling method %p, currentstate=%p\n",471 this_walk_state->prev_op, this_walk_state));472 473 /*474 * Get the namespace entry for the control method we are about to call475 */476 method_node = this_walk_state->method_call_node;477 if (!method_node) {478 return_ACPI_STATUS(AE_NULL_ENTRY);479 }480 481 obj_desc = acpi_ns_get_attached_object(method_node);482 if (!obj_desc) {483 return_ACPI_STATUS(AE_NULL_OBJECT);484 }485 486 /* Init for new method, possibly wait on method mutex */487 488 status =489 acpi_ds_begin_method_execution(method_node, obj_desc,490 this_walk_state);491 if (ACPI_FAILURE(status)) {492 return_ACPI_STATUS(status);493 }494 495 /* Begin method parse/execution. Create a new walk state */496 497 next_walk_state =498 acpi_ds_create_walk_state(obj_desc->method.owner_id, NULL, obj_desc,499 thread);500 if (!next_walk_state) {501 status = AE_NO_MEMORY;502 goto cleanup;503 }504 505 /*506 * The resolved arguments were put on the previous walk state's operand507 * stack. Operands on the previous walk state stack always508 * start at index 0. Also, null terminate the list of arguments509 */510 this_walk_state->operands[this_walk_state->num_operands] = NULL;511 512 /*513 * Allocate and initialize the evaluation information block514 * TBD: this is somewhat inefficient, should change interface to515 * ds_init_aml_walk. For now, keeps this struct off the CPU stack516 */517 info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));518 if (!info) {519 status = AE_NO_MEMORY;520 goto pop_walk_state;521 }522 523 info->parameters = &this_walk_state->operands[0];524 525 status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,526 obj_desc->method.aml_start,527 obj_desc->method.aml_length, info,528 ACPI_IMODE_EXECUTE);529 530 ACPI_FREE(info);531 if (ACPI_FAILURE(status)) {532 goto pop_walk_state;533 }534 535 next_walk_state->method_nesting_depth =536 this_walk_state->method_nesting_depth + 1;537 538 /*539 * Delete the operands on the previous walkstate operand stack540 * (they were copied to new objects)541 */542 for (i = 0; i < obj_desc->method.param_count; i++) {543 acpi_ut_remove_reference(this_walk_state->operands[i]);544 this_walk_state->operands[i] = NULL;545 }546 547 /* Clear the operand stack */548 549 this_walk_state->num_operands = 0;550 551 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,552 "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",553 method_node->name.ascii, next_walk_state));554 555 this_walk_state->method_pathname =556 acpi_ns_get_normalized_pathname(method_node, TRUE);557 this_walk_state->method_is_nested = TRUE;558 559 /* Optional object evaluation log */560 561 ACPI_DEBUG_PRINT_RAW((ACPI_DB_EVALUATION,562 "%-26s: %*s%s\n", " Nested method call",563 next_walk_state->method_nesting_depth * 3, " ",564 &this_walk_state->method_pathname[1]));565 566 /* Invoke an internal method if necessary */567 568 if (obj_desc->method.info_flags & ACPI_METHOD_INTERNAL_ONLY) {569 status =570 obj_desc->method.dispatch.implementation(next_walk_state);571 if (status == AE_OK) {572 status = AE_CTRL_TERMINATE;573 }574 }575 576 return_ACPI_STATUS(status);577 578pop_walk_state:579 580 /* On error, pop the walk state to be deleted from thread */581 582 acpi_ds_pop_walk_state(thread);583 584cleanup:585 586 /* On error, we must terminate the method properly */587 588 acpi_ds_terminate_control_method(obj_desc, next_walk_state);589 acpi_ds_delete_walk_state(next_walk_state);590 591 return_ACPI_STATUS(status);592}593 594/*******************************************************************************595 *596 * FUNCTION: acpi_ds_restart_control_method597 *598 * PARAMETERS: walk_state - State for preempted method (caller)599 * return_desc - Return value from the called method600 *601 * RETURN: Status602 *603 * DESCRIPTION: Restart a method that was preempted by another (nested) method604 * invocation. Handle the return value (if any) from the callee.605 *606 ******************************************************************************/607 608acpi_status609acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,610 union acpi_operand_object *return_desc)611{612 acpi_status status;613 int same_as_implicit_return;614 615 ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);616 617 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,618 "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",619 acpi_ut_get_node_name(walk_state->method_node),620 walk_state->method_call_op, return_desc));621 622 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,623 " ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",624 walk_state->return_used,625 walk_state->results, walk_state));626 627 /* Did the called method return a value? */628 629 if (return_desc) {630 631 /* Is the implicit return object the same as the return desc? */632 633 same_as_implicit_return =634 (walk_state->implicit_return_obj == return_desc);635 636 /* Are we actually going to use the return value? */637 638 if (walk_state->return_used) {639 640 /* Save the return value from the previous method */641 642 status = acpi_ds_result_push(return_desc, walk_state);643 if (ACPI_FAILURE(status)) {644 acpi_ut_remove_reference(return_desc);645 return_ACPI_STATUS(status);646 }647 648 /*649 * Save as THIS method's return value in case it is returned650 * immediately to yet another method651 */652 walk_state->return_desc = return_desc;653 }654 655 /*656 * The following code is the optional support for the so-called657 * "implicit return". Some AML code assumes that the last value of the658 * method is "implicitly" returned to the caller, in the absence of an659 * explicit return value.660 *661 * Just save the last result of the method as the return value.662 *663 * NOTE: this is optional because the ASL language does not actually664 * support this behavior.665 */666 else if (!acpi_ds_do_implicit_return667 (return_desc, walk_state, FALSE)668 || same_as_implicit_return) {669 /*670 * Delete the return value if it will not be used by the671 * calling method or remove one reference if the explicit return672 * is the same as the implicit return value.673 */674 acpi_ut_remove_reference(return_desc);675 }676 }677 678 return_ACPI_STATUS(AE_OK);679}680 681/*******************************************************************************682 *683 * FUNCTION: acpi_ds_terminate_control_method684 *685 * PARAMETERS: method_desc - Method object686 * walk_state - State associated with the method687 *688 * RETURN: None689 *690 * DESCRIPTION: Terminate a control method. Delete everything that the method691 * created, delete all locals and arguments, and delete the parse692 * tree if requested.693 *694 * MUTEX: Interpreter is locked695 *696 ******************************************************************************/697 698void699acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,700 struct acpi_walk_state *walk_state)701{702 703 ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);704 705 /* method_desc is required, walk_state is optional */706 707 if (!method_desc) {708 return_VOID;709 }710 711 if (walk_state) {712 713 /* Delete all arguments and locals */714 715 acpi_ds_method_data_delete_all(walk_state);716 717 /*718 * Delete any namespace objects created anywhere within the719 * namespace by the execution of this method. Unless:720 * 1) This method is a module-level executable code method, in which721 * case we want make the objects permanent.722 * 2) There are other threads executing the method, in which case we723 * will wait until the last thread has completed.724 */725 if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)726 && (method_desc->method.thread_count == 1)) {727 728 /* Delete any direct children of (created by) this method */729 730 (void)acpi_ex_exit_interpreter();731 acpi_ns_delete_namespace_subtree(walk_state->732 method_node);733 (void)acpi_ex_enter_interpreter();734 735 /*736 * Delete any objects that were created by this method737 * elsewhere in the namespace (if any were created).738 * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the739 * deletion such that we don't have to perform an entire740 * namespace walk for every control method execution.741 */742 if (method_desc->method.743 info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {744 (void)acpi_ex_exit_interpreter();745 acpi_ns_delete_namespace_by_owner(method_desc->746 method.747 owner_id);748 (void)acpi_ex_enter_interpreter();749 method_desc->method.info_flags &=750 ~ACPI_METHOD_MODIFIED_NAMESPACE;751 }752 }753 754 /*755 * If method is serialized, release the mutex and restore the756 * current sync level for this thread757 */758 if (method_desc->method.mutex) {759 760 /* Acquisition Depth handles recursive calls */761 762 method_desc->method.mutex->mutex.acquisition_depth--;763 if (!method_desc->method.mutex->mutex.acquisition_depth) {764 walk_state->thread->current_sync_level =765 method_desc->method.mutex->mutex.766 original_sync_level;767 768 acpi_os_release_mutex(method_desc->method.769 mutex->mutex.os_mutex);770 method_desc->method.mutex->mutex.thread_id = 0;771 }772 }773 }774 775 /* Decrement the thread count on the method */776 777 if (method_desc->method.thread_count) {778 method_desc->method.thread_count--;779 } else {780 ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));781 }782 783 /* Are there any other threads currently executing this method? */784 785 if (method_desc->method.thread_count) {786 /*787 * Additional threads. Do not release the owner_id in this case,788 * we immediately reuse it for the next thread executing this method789 */790 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,791 "*** Completed execution of one thread, %u threads remaining\n",792 method_desc->method.thread_count));793 } else {794 /* This is the only executing thread for this method */795 796 /*797 * Support to dynamically change a method from not_serialized to798 * Serialized if it appears that the method is incorrectly written and799 * does not support multiple thread execution. The best example of this800 * is if such a method creates namespace objects and blocks. A second801 * thread will fail with an AE_ALREADY_EXISTS exception.802 *803 * This code is here because we must wait until the last thread exits804 * before marking the method as serialized.805 */806 if (method_desc->method.807 info_flags & ACPI_METHOD_SERIALIZED_PENDING) {808 if (walk_state) {809 ACPI_INFO(("Marking method %4.4s as Serialized "810 "because of AE_ALREADY_EXISTS error",811 walk_state->method_node->name.812 ascii));813 }814 815 /*816 * Method tried to create an object twice and was marked as817 * "pending serialized". The probable cause is that the method818 * cannot handle reentrancy.819 *820 * The method was created as not_serialized, but it tried to create821 * a named object and then blocked, causing the second thread822 * entrance to begin and then fail. Workaround this problem by823 * marking the method permanently as Serialized when the last824 * thread exits here.825 */826 method_desc->method.info_flags &=827 ~ACPI_METHOD_SERIALIZED_PENDING;828 829 method_desc->method.info_flags |=830 (ACPI_METHOD_SERIALIZED |831 ACPI_METHOD_IGNORE_SYNC_LEVEL);832 method_desc->method.sync_level = 0;833 }834 835 /* No more threads, we can free the owner_id */836 837 if (!838 (method_desc->method.839 info_flags & ACPI_METHOD_MODULE_LEVEL)) {840 acpi_ut_release_owner_id(&method_desc->method.owner_id);841 }842 }843 844 acpi_ex_stop_trace_method((struct acpi_namespace_node *)method_desc->845 method.node, method_desc, walk_state);846 847 return_VOID;848}849