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/******************************************************************************

 *

 * Module Name: dsmethod - Parser/Interpreter interface - control method parsing

 *

 *****************************************************************************/

/*

 * Copyright (C) 2000 - 2015, Intel Corp.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions, and the following disclaimer,

 *    without modification.

 * 2. Redistributions in binary form must reproduce at minimum a disclaimer

 *    substantially similar to the "NO WARRANTY" disclaimer below

 *    ("Disclaimer") and any redistribution must be conditioned upon

 *    including a substantially similar Disclaimer requirement for further

 *    binary redistribution.

 * 3. Neither the names of the above-listed copyright holders nor the names

 *    of any contributors may be used to endorse or promote products derived

 *    from this software without specific prior written permission.

 *

 * Alternatively, this software may be distributed under the terms of the

 * GNU General Public License ("GPL") version 2 as published by the Free

 * Software Foundation.

 *

 * NO WARRANTY

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING

 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

 * POSSIBILITY OF SUCH DAMAGES.

 */

#include 

#include "accommon.h"

#include "acdispat.h"

#include "acinterp.h"

#include "acnamesp.h"

#include "acparser.h"

#include "amlcode.h"

#include "acdebug.h"

#define _COMPONENT          ACPI_DISPATCHER

ACPI_MODULE_NAME("dsmethod")

/* Local prototypes */

static acpi_status

acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,

			     union acpi_parse_object **out_op);

static acpi_status

acpi_ds_create_method_mutex(union acpi_operand_object *method_desc);

/*******************************************************************************

 *

 * FUNCTION:    acpi_ds_auto_serialize_method

 *

 * PARAMETERS:  node                        - Namespace Node of the method

 *              obj_desc                    - Method object attached to node

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Parse a control method AML to scan for control methods that

 *              need serialization due to the creation of named objects.

 *

 * NOTE: It is a bit of overkill to mark all such methods serialized, since

 * there is only a problem if the method actually blocks during execution.

 * A blocking operation is, for example, a Sleep() operation, or any access

 * to an operation region. However, it is probably not possible to easily

 * detect whether a method will block or not, so we simply mark all suspicious

 * methods as serialized.

 *

 * NOTE2: This code is essentially a generic routine for parsing a single

 * control method.

 *

 ******************************************************************************/

acpi_status

acpi_ds_auto_serialize_method(struct acpi_namespace_node *node,

			      union acpi_operand_object *obj_desc)

{

	acpi_status status;

	union acpi_parse_object *op = NULL;

	struct acpi_walk_state *walk_state;

	ACPI_FUNCTION_TRACE_PTR(ds_auto_serialize_method, node);

	ACPI_DEBUG_PRINT((ACPI_DB_PARSE,

			  "Method auto-serialization parse [%4.4s] %p\n",

			  acpi_ut_get_node_name(node), node));

	/* Create/Init a root op for the method parse tree */

	op = acpi_ps_alloc_op(AML_METHOD_OP, obj_desc->method.aml_start);

	if (!op) {

		return_ACPI_STATUS(AE_NO_MEMORY);

	}

	acpi_ps_set_name(op, node->name.integer);

	op->common.node = node;

	/* Create and initialize a new walk state */

	walk_state =

	    acpi_ds_create_walk_state(node->owner_id, NULL, NULL, NULL);

	if (!walk_state) {

		acpi_ps_free_op(op);

		return_ACPI_STATUS(AE_NO_MEMORY);

	}

	status =

	    acpi_ds_init_aml_walk(walk_state, op, node,

				  obj_desc->method.aml_start,

				  obj_desc->method.aml_length, NULL, 0);

	if (ACPI_FAILURE(status)) {

		acpi_ds_delete_walk_state(walk_state);

		acpi_ps_free_op(op);

		return_ACPI_STATUS(status);

	}

	walk_state->descending_callback = acpi_ds_detect_named_opcodes;

	/* Parse the method, scan for creation of named objects */

	status = acpi_ps_parse_aml(walk_state);

	acpi_ps_delete_parse_tree(op);

	return_ACPI_STATUS(status);

}

/*******************************************************************************

 *

 * FUNCTION:    acpi_ds_detect_named_opcodes

 *

 * PARAMETERS:  walk_state      - Current state of the parse tree walk

 *              out_op          - Unused, required for parser interface

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Descending callback used during the loading of ACPI tables.

 *              Currently used to detect methods that must be marked serialized

 *              in order to avoid problems with the creation of named objects.

 *

 ******************************************************************************/

static acpi_status

acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,

			     union acpi_parse_object **out_op)

{

	ACPI_FUNCTION_NAME(acpi_ds_detect_named_opcodes);

	/* We are only interested in opcodes that create a new name */

	if (!

	    (walk_state->op_info->

	     flags & (AML_NAMED | AML_CREATE | AML_FIELD))) {

		return (AE_OK);

	}

	/*

	 * At this point, we know we have a Named object opcode.

	 * Mark the method as serialized. Later code will create a mutex for

	 * this method to enforce serialization.

	 *

	 * Note, ACPI_METHOD_IGNORE_SYNC_LEVEL flag means that we will ignore the

	 * Sync Level mechanism for this method, even though it is now serialized.

	 * Otherwise, there can be conflicts with existing ASL code that actually

	 * uses sync levels.

	 */

	walk_state->method_desc->method.sync_level = 0;

	walk_state->method_desc->method.info_flags |=

	    (ACPI_METHOD_SERIALIZED | ACPI_METHOD_IGNORE_SYNC_LEVEL);

	ACPI_DEBUG_PRINT((ACPI_DB_INFO,

			  "Method serialized [%4.4s] %p - [%s] (%4.4X)\n",

			  walk_state->method_node->name.ascii,

			  walk_state->method_node, walk_state->op_info->name,

			  walk_state->opcode));

	/* Abort the parse, no need to examine this method any further */

	return (AE_CTRL_TERMINATE);

}

/*******************************************************************************

 *

 * FUNCTION:    acpi_ds_method_error

 *

 * PARAMETERS:  status          - Execution status

 *              walk_state      - Current state

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Called on method error. Invoke the global exception handler if

 *              present, dump the method data if the debugger is configured

 *

 *              Note: Allows the exception handler to change the status code

 *

 ******************************************************************************/

acpi_status

acpi_ds_method_error(acpi_status status, struct acpi_walk_state * walk_state)

{

	u32 aml_offset;

	ACPI_FUNCTION_ENTRY();

	/* Ignore AE_OK and control exception codes */

	if (ACPI_SUCCESS(status) || (status & AE_CODE_CONTROL)) {

		return (status);

	}

	/* Invoke the global exception handler */

	if (acpi_gbl_exception_handler) {

		/* Exit the interpreter, allow handler to execute methods */

		acpi_ex_exit_interpreter();

		/*

		 * Handler can map the exception code to anything it wants, including

		 * AE_OK, in which case the executing method will not be aborted.

		 */

		aml_offset = (u32)ACPI_PTR_DIFF(walk_state->aml,

						walk_state->parser_state.

						aml_start);

		status = acpi_gbl_exception_handler(status,

						    walk_state->method_node ?

						    walk_state->method_node->

						    name.integer : 0,

						    walk_state->opcode,

						    aml_offset, NULL);

		acpi_ex_enter_interpreter();

	}

	acpi_ds_clear_implicit_return(walk_state);

	if (ACPI_FAILURE(status)) {

		acpi_ds_dump_method_stack(status, walk_state, walk_state->op);

		/* Display method locals/args if debugger is present */

#ifdef ACPI_DEBUGGER

		acpi_db_dump_method_info(status, walk_state);

#endif

	}

	return (status);

}

/*******************************************************************************

 *

 * FUNCTION:    acpi_ds_create_method_mutex

 *

 * PARAMETERS:  obj_desc            - The method object

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Create a mutex object for a serialized control method

 *

 ******************************************************************************/

static acpi_status

acpi_ds_create_method_mutex(union acpi_operand_object *method_desc)

{

	union acpi_operand_object *mutex_desc;

	acpi_status status;

	ACPI_FUNCTION_TRACE(ds_create_method_mutex);

	/* Create the new mutex object */

	mutex_desc = acpi_ut_create_internal_object(ACPI_TYPE_MUTEX);

	if (!mutex_desc) {

		return_ACPI_STATUS(AE_NO_MEMORY);

	}

	/* Create the actual OS Mutex */

	status = acpi_os_create_mutex(&mutex_desc->mutex.os_mutex);

	if (ACPI_FAILURE(status)) {

		acpi_ut_delete_object_desc(mutex_desc);

		return_ACPI_STATUS(status);

	}

	mutex_desc->mutex.sync_level = method_desc->method.sync_level;

	method_desc->method.mutex = mutex_desc;

	return_ACPI_STATUS(AE_OK);

}

/*******************************************************************************

 *

 * FUNCTION:    acpi_ds_begin_method_execution

 *

 * PARAMETERS:  method_node         - Node of the method

 *              obj_desc            - The method object

 *              walk_state          - current state, NULL if not yet executing

 *                                    a method.

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Prepare a method for execution. Parses the method if necessary,

 *              increments the thread count, and waits at the method semaphore

 *              for clearance to execute.

 *

 ******************************************************************************/

acpi_status

acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,

			       union acpi_operand_object *obj_desc,

			       struct acpi_walk_state *walk_state)

{

	acpi_status status = AE_OK;

	ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);

	if (!method_node) {

		return_ACPI_STATUS(AE_NULL_ENTRY);

	}

	acpi_ex_start_trace_method(method_node, obj_desc, walk_state);

	/* Prevent wraparound of thread count */

	if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {

		ACPI_ERROR((AE_INFO,

			    "Method reached maximum reentrancy limit (255)"));

		return_ACPI_STATUS(AE_AML_METHOD_LIMIT);

	}

	/*

	 * If this method is serialized, we need to acquire the method mutex.

	 */

	if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {

		/*

		 * Create a mutex for the method if it is defined to be Serialized

		 * and a mutex has not already been created. We defer the mutex creation

		 * until a method is actually executed, to minimize the object count

		 */

		if (!obj_desc->method.mutex) {

			status = acpi_ds_create_method_mutex(obj_desc);

			if (ACPI_FAILURE(status)) {

				return_ACPI_STATUS(status);

			}

		}

		/*

		 * The current_sync_level (per-thread) must be less than or equal to

		 * the sync level of the method. This mechanism provides some

		 * deadlock prevention.

		 *

		 * If the method was auto-serialized, we just ignore the sync level

		 * mechanism, because auto-serialization of methods can interfere

		 * with ASL code that actually uses sync levels.

		 *

		 * Top-level method invocation has no walk state at this point

		 */

		if (walk_state &&

		    (!(obj_desc->method.

		       info_flags & ACPI_METHOD_IGNORE_SYNC_LEVEL))

		    && (walk_state->thread->current_sync_level >

			obj_desc->method.mutex->mutex.sync_level)) {

			ACPI_ERROR((AE_INFO,

				    "Cannot acquire Mutex for method [%4.4s], current SyncLevel is too large (%u)",

				    acpi_ut_get_node_name(method_node),

				    walk_state->thread->current_sync_level));

			return_ACPI_STATUS(AE_AML_MUTEX_ORDER);

		}

		/*

		 * Obtain the method mutex if necessary. Do not acquire mutex for a

		 * recursive call.

		 */

		if (!walk_state ||

		    !obj_desc->method.mutex->mutex.thread_id ||

		    (walk_state->thread->thread_id !=

		     obj_desc->method.mutex->mutex.thread_id)) {

			/*

			 * Acquire the method mutex. This releases the interpreter if we

			 * block (and reacquires it before it returns)

			 */

			status =

			    acpi_ex_system_wait_mutex(obj_desc->method.mutex->

						      mutex.os_mutex,

						      ACPI_WAIT_FOREVER);

			if (ACPI_FAILURE(status)) {

				return_ACPI_STATUS(status);

			}

			/* Update the mutex and walk info and save the original sync_level */

			if (walk_state) {

				obj_desc->method.mutex->mutex.

				    original_sync_level =

				    walk_state->thread->current_sync_level;

				obj_desc->method.mutex->mutex.thread_id =

				    walk_state->thread->thread_id;

				walk_state->thread->current_sync_level =

				    obj_desc->method.sync_level;

			} else {

				obj_desc->method.mutex->mutex.

				    original_sync_level =

				    obj_desc->method.mutex->mutex.sync_level;

				obj_desc->method.mutex->mutex.thread_id =

				    acpi_os_get_thread_id();

			}

		}

		/* Always increase acquisition depth */

		obj_desc->method.mutex->mutex.acquisition_depth++;

	}

	/*

	 * Allocate an Owner ID for this method, only if this is the first thread

	 * to begin concurrent execution. We only need one owner_id, even if the

	 * method is invoked recursively.

	 */

	if (!obj_desc->method.owner_id) {

		status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);

		if (ACPI_FAILURE(status)) {

			goto cleanup;

		}

	}

	/*

	 * Increment the method parse tree thread count since it has been

	 * reentered one more time (even if it is the same thread)

	 */

	obj_desc->method.thread_count++;

	acpi_method_count++;

	return_ACPI_STATUS(status);

cleanup:

	/* On error, must release the method mutex (if present) */

	if (obj_desc->method.mutex) {

		acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);

	}

	return_ACPI_STATUS(status);

}

/*******************************************************************************

 *

 * FUNCTION:    acpi_ds_call_control_method

 *

 * PARAMETERS:  thread              - Info for this thread

 *              this_walk_state     - Current walk state

 *              op                  - Current Op to be walked

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Transfer execution to a called control method

 *

 ******************************************************************************/

acpi_status

acpi_ds_call_control_method(struct acpi_thread_state *thread,

			    struct acpi_walk_state *this_walk_state,

			    union acpi_parse_object *op)

{

	acpi_status status;

	struct acpi_namespace_node *method_node;

	struct acpi_walk_state *next_walk_state = NULL;

	union acpi_operand_object *obj_desc;

	struct acpi_evaluate_info *info;

	u32 i;

	ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);

	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,

			  "Calling method %p, currentstate=%p\n",

			  this_walk_state->prev_op, this_walk_state));

	/*

	 * Get the namespace entry for the control method we are about to call

	 */

	method_node = this_walk_state->method_call_node;

	if (!method_node) {

		return_ACPI_STATUS(AE_NULL_ENTRY);

	}

	obj_desc = acpi_ns_get_attached_object(method_node);

	if (!obj_desc) {

		return_ACPI_STATUS(AE_NULL_OBJECT);

	}

	/* Init for new method, possibly wait on method mutex */

	status = acpi_ds_begin_method_execution(method_node, obj_desc,

						this_walk_state);

	if (ACPI_FAILURE(status)) {

		return_ACPI_STATUS(status);

	}

	/* Begin method parse/execution. Create a new walk state */

	next_walk_state = acpi_ds_create_walk_state(obj_desc->method.owner_id,

						    NULL, obj_desc, thread);

	if (!next_walk_state) {

		status = AE_NO_MEMORY;

		goto cleanup;

	}

	/*

	 * The resolved arguments were put on the previous walk state's operand

	 * stack. Operands on the previous walk state stack always

	 * start at index 0. Also, null terminate the list of arguments

	 */

	this_walk_state->operands[this_walk_state->num_operands] = NULL;

	/*

	 * Allocate and initialize the evaluation information block

	 * TBD: this is somewhat inefficient, should change interface to

	 * ds_init_aml_walk. For now, keeps this struct off the CPU stack

	 */

	info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));

	if (!info) {

		status = AE_NO_MEMORY;

		goto cleanup;

	}

	info->parameters = &this_walk_state->operands[0];

	status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,

				       obj_desc->method.aml_start,

				       obj_desc->method.aml_length, info,

				       ACPI_IMODE_EXECUTE);

	ACPI_FREE(info);

	if (ACPI_FAILURE(status)) {

		goto cleanup;

	}

	/*

	 * Delete the operands on the previous walkstate operand stack

	 * (they were copied to new objects)

	 */

	for (i = 0; i < obj_desc->method.param_count; i++) {

		acpi_ut_remove_reference(this_walk_state->operands[i]);

		this_walk_state->operands[i] = NULL;

	}

	/* Clear the operand stack */

	this_walk_state->num_operands = 0;

	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,

			  "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",

			  method_node->name.ascii, next_walk_state));

	/* Invoke an internal method if necessary */

	if (obj_desc->method.info_flags & ACPI_METHOD_INTERNAL_ONLY) {

		status =

		    obj_desc->method.dispatch.implementation(next_walk_state);

		if (status == AE_OK) {

			status = AE_CTRL_TERMINATE;

		}

	}

	return_ACPI_STATUS(status);

cleanup:

	/* On error, we must terminate the method properly */

	acpi_ds_terminate_control_method(obj_desc, next_walk_state);

	acpi_ds_delete_walk_state(next_walk_state);

	return_ACPI_STATUS(status);

}

/*******************************************************************************

 *

 * FUNCTION:    acpi_ds_restart_control_method

 *

 * PARAMETERS:  walk_state          - State for preempted method (caller)

 *              return_desc         - Return value from the called method

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Restart a method that was preempted by another (nested) method

 *              invocation. Handle the return value (if any) from the callee.

 *

 ******************************************************************************/

acpi_status

acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,

			       union acpi_operand_object *return_desc)

{

	acpi_status status;

	int same_as_implicit_return;

	ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);

	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,

			  "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",

			  acpi_ut_get_node_name(walk_state->method_node),

			  walk_state->method_call_op, return_desc));

	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,

			  "    ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",

			  walk_state->return_used,

			  walk_state->results, walk_state));

	/* Did the called method return a value? */

	if (return_desc) {

		/* Is the implicit return object the same as the return desc? */

		same_as_implicit_return =

		    (walk_state->implicit_return_obj == return_desc);

		/* Are we actually going to use the return value? */

		if (walk_state->return_used) {

			/* Save the return value from the previous method */

			status = acpi_ds_result_push(return_desc, walk_state);

			if (ACPI_FAILURE(status)) {

				acpi_ut_remove_reference(return_desc);

				return_ACPI_STATUS(status);

			}

			/*

			 * Save as THIS method's return value in case it is returned

			 * immediately to yet another method

			 */

			walk_state->return_desc = return_desc;

		}

		/*

		 * The following code is the optional support for the so-called

		 * "implicit return". Some AML code assumes that the last value of the

		 * method is "implicitly" returned to the caller, in the absence of an

		 * explicit return value.

		 *

		 * Just save the last result of the method as the return value.

		 *

		 * NOTE: this is optional because the ASL language does not actually

		 * support this behavior.

		 */

		else if (!acpi_ds_do_implicit_return

			 (return_desc, walk_state, FALSE)

			 || same_as_implicit_return) {

			/*

			 * Delete the return value if it will not be used by the

			 * calling method or remove one reference if the explicit return

			 * is the same as the implicit return value.

			 */

			acpi_ut_remove_reference(return_desc);

		}

	}

	return_ACPI_STATUS(AE_OK);

}

/*******************************************************************************

 *

 * FUNCTION:    acpi_ds_terminate_control_method

 *

 * PARAMETERS:  method_desc         - Method object

 *              walk_state          - State associated with the method

 *

 * RETURN:      None

 *

 * DESCRIPTION: Terminate a control method. Delete everything that the method

 *              created, delete all locals and arguments, and delete the parse

 *              tree if requested.

 *

 * MUTEX:       Interpreter is locked

 *

 ******************************************************************************/

void

acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,

				 struct acpi_walk_state *walk_state)

{

	ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);

	/* method_desc is required, walk_state is optional */

	if (!method_desc) {

		return_VOID;

	}

	if (walk_state) {

		/* Delete all arguments and locals */

		acpi_ds_method_data_delete_all(walk_state);

		/*

		 * If method is serialized, release the mutex and restore the

		 * current sync level for this thread

		 */

		if (method_desc->method.mutex) {

			/* Acquisition Depth handles recursive calls */

			method_desc->method.mutex->mutex.acquisition_depth--;

			if (!method_desc->method.mutex->mutex.acquisition_depth) {

				walk_state->thread->current_sync_level =

				    method_desc->method.mutex->mutex.

				    original_sync_level;

				acpi_os_release_mutex(method_desc->method.

						      mutex->mutex.os_mutex);

				method_desc->method.mutex->mutex.thread_id = 0;

			}

		}

		/*

		 * Delete any namespace objects created anywhere within the

		 * namespace by the execution of this method. Unless:

		 * 1) This method is a module-level executable code method, in which

		 *    case we want make the objects permanent.

		 * 2) There are other threads executing the method, in which case we

		 *    will wait until the last thread has completed.

		 */

		if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)

		    && (method_desc->method.thread_count == 1)) {

			/* Delete any direct children of (created by) this method */

			acpi_ns_delete_namespace_subtree(walk_state->

							 method_node);

			/*

			 * Delete any objects that were created by this method

			 * elsewhere in the namespace (if any were created).

			 * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the

			 * deletion such that we don't have to perform an entire

			 * namespace walk for every control method execution.

			 */

			if (method_desc->method.

			    info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {

				acpi_ns_delete_namespace_by_owner(method_desc->

								  method.

								  owner_id);

				method_desc->method.info_flags &=

				    ~ACPI_METHOD_MODIFIED_NAMESPACE;

			}

		}

	}

	/* Decrement the thread count on the method */

	if (method_desc->method.thread_count) {

		method_desc->method.thread_count--;

	} else {

		ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));

	}

	/* Are there any other threads currently executing this method? */

	if (method_desc->method.thread_count) {

		/*

		 * Additional threads. Do not release the owner_id in this case,

		 * we immediately reuse it for the next thread executing this method

		 */

		ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,

				  "*** Completed execution of one thread, %u threads remaining\n",

				  method_desc->method.thread_count));

	} else {

		/* This is the only executing thread for this method */

		/*

		 * Support to dynamically change a method from not_serialized to

		 * Serialized if it appears that the method is incorrectly written and

		 * does not support multiple thread execution. The best example of this

		 * is if such a method creates namespace objects and blocks. A second

		 * thread will fail with an AE_ALREADY_EXISTS exception.

		 *

		 * This code is here because we must wait until the last thread exits

		 * before marking the method as serialized.

		 */

		if (method_desc->method.

		    info_flags & ACPI_METHOD_SERIALIZED_PENDING) {

			if (walk_state) {

				ACPI_INFO((AE_INFO,

					   "Marking method %4.4s as Serialized because of AE_ALREADY_EXISTS error",

					   walk_state->method_node->name.

					   ascii));

			}

			/*

			 * Method tried to create an object twice and was marked as

			 * "pending serialized". The probable cause is that the method

			 * cannot handle reentrancy.

			 *

			 * The method was created as not_serialized, but it tried to create

			 * a named object and then blocked, causing the second thread

			 * entrance to begin and then fail. Workaround this problem by

			 * marking the method permanently as Serialized when the last

			 * thread exits here.

			 */

			method_desc->method.info_flags &=

			    ~ACPI_METHOD_SERIALIZED_PENDING;

			method_desc->method.info_flags |=

			    (ACPI_METHOD_SERIALIZED |

			     ACPI_METHOD_IGNORE_SYNC_LEVEL);

			method_desc->method.sync_level = 0;

		}

		/* No more threads, we can free the owner_id */

		if (!

		    (method_desc->method.

		     info_flags & ACPI_METHOD_MODULE_LEVEL)) {

			acpi_ut_release_owner_id(&method_desc->method.owner_id);

		}

	}

	acpi_ex_stop_trace_method((struct acpi_namespace_node *)method_desc->

				  method.node, method_desc, walk_state);

	return_VOID;

}