FreeBSD/Linux Kernel Cross Reference
sys/contrib/dev/acpica/components/executer/exmutex.c

     /******************************************************************************
      *
      * Module Name: exmutex - ASL Mutex Acquire/Release functions
      *
      *****************************************************************************/
     
     /******************************************************************************
      *
      * 1. Copyright Notice
     *
     * Some or all of this work - Copyright (c) 1999 - 2022, Intel Corp.
     * All rights reserved.
     *
     * 2. License
     *
     * 2.1. This is your license from Intel Corp. under its intellectual property
     * rights. You may have additional license terms from the party that provided
     * you this software, covering your right to use that party's intellectual
     * property rights.
     *
     * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
     * copy of the source code appearing in this file ("Covered Code") an
     * irrevocable, perpetual, worldwide license under Intel's copyrights in the
     * base code distributed originally by Intel ("Original Intel Code") to copy,
     * make derivatives, distribute, use and display any portion of the Covered
     * Code in any form, with the right to sublicense such rights; and
     *
     * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
     * license (with the right to sublicense), under only those claims of Intel
     * patents that are infringed by the Original Intel Code, to make, use, sell,
     * offer to sell, and import the Covered Code and derivative works thereof
     * solely to the minimum extent necessary to exercise the above copyright
     * license, and in no event shall the patent license extend to any additions
     * to or modifications of the Original Intel Code. No other license or right
     * is granted directly or by implication, estoppel or otherwise;
     *
     * The above copyright and patent license is granted only if the following
     * conditions are met:
     *
     * 3. Conditions
     *
     * 3.1. Redistribution of Source with Rights to Further Distribute Source.
     * Redistribution of source code of any substantial portion of the Covered
     * Code or modification with rights to further distribute source must include
     * the above Copyright Notice, the above License, this list of Conditions,
     * and the following Disclaimer and Export Compliance provision. In addition,
     * Licensee must cause all Covered Code to which Licensee contributes to
     * contain a file documenting the changes Licensee made to create that Covered
     * Code and the date of any change. Licensee must include in that file the
     * documentation of any changes made by any predecessor Licensee. Licensee
     * must include a prominent statement that the modification is derived,
     * directly or indirectly, from Original Intel Code.
     *
     * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
     * Redistribution of source code of any substantial portion of the Covered
     * Code or modification without rights to further distribute source must
     * include the following Disclaimer and Export Compliance provision in the
     * documentation and/or other materials provided with distribution. In
     * addition, Licensee may not authorize further sublicense of source of any
     * portion of the Covered Code, and must include terms to the effect that the
     * license from Licensee to its licensee is limited to the intellectual
     * property embodied in the software Licensee provides to its licensee, and
     * not to intellectual property embodied in modifications its licensee may
     * make.
     *
     * 3.3. Redistribution of Executable. Redistribution in executable form of any
     * substantial portion of the Covered Code or modification must reproduce the
     * above Copyright Notice, and the following Disclaimer and Export Compliance
     * provision in the documentation and/or other materials provided with the
     * distribution.
     *
     * 3.4. Intel retains all right, title, and interest in and to the Original
     * Intel Code.
     *
     * 3.5. Neither the name Intel nor any other trademark owned or controlled by
     * Intel shall be used in advertising or otherwise to promote the sale, use or
     * other dealings in products derived from or relating to the Covered Code
     * without prior written authorization from Intel.
     *
     * 4. Disclaimer and Export Compliance
     *
     * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
     * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
     * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
     * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
     * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
     * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
     * PARTICULAR PURPOSE.
     *
     * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
     * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
     * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
     * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
     * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
     * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
     * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
     * LIMITED REMEDY.
     *
     * 4.3. Licensee shall not export, either directly or indirectly, any of this
    * software or system incorporating such software without first obtaining any
    * required license or other approval from the U. S. Department of Commerce or
    * any other agency or department of the United States Government. In the
    * event Licensee exports any such software from the United States or
    * re-exports any such software from a foreign destination, Licensee shall
    * ensure that the distribution and export/re-export of the software is in
    * compliance with all laws, regulations, orders, or other restrictions of the
    * U.S. Export Administration Regulations. Licensee agrees that neither it nor
    * any of its subsidiaries will export/re-export any technical data, process,
    * software, or service, directly or indirectly, to any country for which the
    * United States government or any agency thereof requires an export license,
    * other governmental approval, or letter of assurance, without first obtaining
    * such license, approval or letter.
    *
    *****************************************************************************
    *
    * Alternatively, you may choose to be licensed under the terms of the
    * following license:
    *
    * 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.
    *
    * 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 MERCHANTABILITY AND FITNESS FOR
    * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    * 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 DAMAGE.
    *
    * Alternatively, you may choose to be licensed under the terms of the
    * GNU General Public License ("GPL") version 2 as published by the Free
    * Software Foundation.
    *
    *****************************************************************************/
   
   #include <contrib/dev/acpica/include/acpi.h>
   #include <contrib/dev/acpica/include/accommon.h>
   #include <contrib/dev/acpica/include/acinterp.h>
   #include <contrib/dev/acpica/include/acevents.h>
   
   #define _COMPONENT          ACPI_EXECUTER
           ACPI_MODULE_NAME    ("exmutex")
   
   /* Local prototypes */
   
   static void
   AcpiExLinkMutex (
       ACPI_OPERAND_OBJECT     *ObjDesc,
       ACPI_THREAD_STATE       *Thread);
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExUnlinkMutex
    *
    * PARAMETERS:  ObjDesc             - The mutex to be unlinked
    *
    * RETURN:      None
    *
    * DESCRIPTION: Remove a mutex from the "AcquiredMutex" list
    *
    ******************************************************************************/
   
   void
   AcpiExUnlinkMutex (
       ACPI_OPERAND_OBJECT     *ObjDesc)
   {
       ACPI_THREAD_STATE       *Thread = ObjDesc->Mutex.OwnerThread;
   
   
       if (!Thread)
       {
           return;
       }
   
       /* Doubly linked list */
   
       if (ObjDesc->Mutex.Next)
       {
           (ObjDesc->Mutex.Next)->Mutex.Prev = ObjDesc->Mutex.Prev;
       }
   
       if (ObjDesc->Mutex.Prev)
       {
           (ObjDesc->Mutex.Prev)->Mutex.Next = ObjDesc->Mutex.Next;
   
           /*
            * Migrate the previous sync level associated with this mutex to
            * the previous mutex on the list so that it may be preserved.
            * This handles the case where several mutexes have been acquired
            * at the same level, but are not released in opposite order.
            */
           (ObjDesc->Mutex.Prev)->Mutex.OriginalSyncLevel =
               ObjDesc->Mutex.OriginalSyncLevel;
       }
       else
       {
           Thread->AcquiredMutexList = ObjDesc->Mutex.Next;
       }
   }
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExLinkMutex
    *
    * PARAMETERS:  ObjDesc             - The mutex to be linked
    *              Thread              - Current executing thread object
    *
    * RETURN:      None
    *
    * DESCRIPTION: Add a mutex to the "AcquiredMutex" list for this walk
    *
    ******************************************************************************/
   
   static void
   AcpiExLinkMutex (
       ACPI_OPERAND_OBJECT     *ObjDesc,
       ACPI_THREAD_STATE       *Thread)
   {
       ACPI_OPERAND_OBJECT     *ListHead;
   
   
       ListHead = Thread->AcquiredMutexList;
   
       /* This object will be the first object in the list */
   
       ObjDesc->Mutex.Prev = NULL;
       ObjDesc->Mutex.Next = ListHead;
   
       /* Update old first object to point back to this object */
   
       if (ListHead)
       {
           ListHead->Mutex.Prev = ObjDesc;
       }
   
       /* Update list head */
   
       Thread->AcquiredMutexList = ObjDesc;
   }
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExAcquireMutexObject
    *
    * PARAMETERS:  Timeout             - Timeout in milliseconds
    *              ObjDesc             - Mutex object
    *              ThreadId            - Current thread state
    *
    * RETURN:      Status
    *
    * DESCRIPTION: Acquire an AML mutex, low-level interface. Provides a common
    *              path that supports multiple acquires by the same thread.
    *
    * MUTEX:       Interpreter must be locked
    *
    * NOTE: This interface is called from three places:
    * 1) From AcpiExAcquireMutex, via an AML Acquire() operator
    * 2) From AcpiExAcquireGlobalLock when an AML Field access requires the
    *    global lock
    * 3) From the external interface, AcpiAcquireGlobalLock
    *
    ******************************************************************************/
   
   ACPI_STATUS
   AcpiExAcquireMutexObject (
       UINT16                  Timeout,
       ACPI_OPERAND_OBJECT     *ObjDesc,
       ACPI_THREAD_ID          ThreadId)
   {
       ACPI_STATUS             Status;
   
   
       ACPI_FUNCTION_TRACE_PTR (ExAcquireMutexObject, ObjDesc);
   
   
       if (!ObjDesc)
       {
           return_ACPI_STATUS (AE_BAD_PARAMETER);
       }
   
       /* Support for multiple acquires by the owning thread */
   
       if (ObjDesc->Mutex.ThreadId == ThreadId)
       {
           /*
            * The mutex is already owned by this thread, just increment the
            * acquisition depth
            */
           ObjDesc->Mutex.AcquisitionDepth++;
           return_ACPI_STATUS (AE_OK);
       }
   
       /* Acquire the mutex, wait if necessary. Special case for Global Lock */
   
       if (ObjDesc == AcpiGbl_GlobalLockMutex)
       {
           Status = AcpiEvAcquireGlobalLock (Timeout);
       }
       else
       {
           Status = AcpiExSystemWaitMutex (ObjDesc->Mutex.OsMutex, Timeout);
       }
   
       if (ACPI_FAILURE (Status))
       {
           /* Includes failure from a timeout on TimeDesc */
   
           return_ACPI_STATUS (Status);
       }
   
       /* Acquired the mutex: update mutex object */
   
       ObjDesc->Mutex.ThreadId = ThreadId;
       ObjDesc->Mutex.AcquisitionDepth = 1;
       ObjDesc->Mutex.OriginalSyncLevel = 0;
       ObjDesc->Mutex.OwnerThread = NULL;      /* Used only for AML Acquire() */
   
       return_ACPI_STATUS (AE_OK);
   }
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExAcquireMutex
    *
    * PARAMETERS:  TimeDesc            - Timeout integer
    *              ObjDesc             - Mutex object
    *              WalkState           - Current method execution state
    *
    * RETURN:      Status
    *
    * DESCRIPTION: Acquire an AML mutex
    *
    ******************************************************************************/
   
   ACPI_STATUS
   AcpiExAcquireMutex (
       ACPI_OPERAND_OBJECT     *TimeDesc,
       ACPI_OPERAND_OBJECT     *ObjDesc,
       ACPI_WALK_STATE         *WalkState)
   {
       ACPI_STATUS             Status;
   
   
       ACPI_FUNCTION_TRACE_PTR (ExAcquireMutex, ObjDesc);
   
   
       if (!ObjDesc)
       {
           return_ACPI_STATUS (AE_BAD_PARAMETER);
       }
   
       /* Must have a valid thread state struct */
   
       if (!WalkState->Thread)
       {
           ACPI_ERROR ((AE_INFO,
               "Cannot acquire Mutex [%4.4s], null thread info",
               AcpiUtGetNodeName (ObjDesc->Mutex.Node)));
           return_ACPI_STATUS (AE_AML_INTERNAL);
       }
   
       /*
        * Current sync level must be less than or equal to the sync level
        * of the mutex. This mechanism provides some deadlock prevention.
        */
       if (WalkState->Thread->CurrentSyncLevel > ObjDesc->Mutex.SyncLevel)
       {
           ACPI_ERROR ((AE_INFO,
               "Cannot acquire Mutex [%4.4s], "
               "current SyncLevel is too large (%u)",
               AcpiUtGetNodeName (ObjDesc->Mutex.Node),
               WalkState->Thread->CurrentSyncLevel));
           return_ACPI_STATUS (AE_AML_MUTEX_ORDER);
       }
   
       ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,
           "Acquiring: Mutex SyncLevel %u, Thread SyncLevel %u, "
           "Depth %u TID %p\n",
           ObjDesc->Mutex.SyncLevel, WalkState->Thread->CurrentSyncLevel,
           ObjDesc->Mutex.AcquisitionDepth, WalkState->Thread));
   
       Status = AcpiExAcquireMutexObject ((UINT16) TimeDesc->Integer.Value,
           ObjDesc, WalkState->Thread->ThreadId);
   
       if (ACPI_SUCCESS (Status) && ObjDesc->Mutex.AcquisitionDepth == 1)
       {
           /* Save Thread object, original/current sync levels */
   
           ObjDesc->Mutex.OwnerThread = WalkState->Thread;
           ObjDesc->Mutex.OriginalSyncLevel =
               WalkState->Thread->CurrentSyncLevel;
           WalkState->Thread->CurrentSyncLevel =
               ObjDesc->Mutex.SyncLevel;
   
           /* Link the mutex to the current thread for force-unlock at method exit */
   
           AcpiExLinkMutex (ObjDesc, WalkState->Thread);
       }
   
       ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,
           "Acquired: Mutex SyncLevel %u, Thread SyncLevel %u, Depth %u\n",
           ObjDesc->Mutex.SyncLevel, WalkState->Thread->CurrentSyncLevel,
           ObjDesc->Mutex.AcquisitionDepth));
   
       return_ACPI_STATUS (Status);
   }
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExReleaseMutexObject
    *
    * PARAMETERS:  ObjDesc             - The object descriptor for this op
    *
    * RETURN:      Status
    *
    * DESCRIPTION: Release a previously acquired Mutex, low level interface.
    *              Provides a common path that supports multiple releases (after
    *              previous multiple acquires) by the same thread.
    *
    * MUTEX:       Interpreter must be locked
    *
    * NOTE: This interface is called from three places:
    * 1) From AcpiExReleaseMutex, via an AML Acquire() operator
    * 2) From AcpiExReleaseGlobalLock when an AML Field access requires the
    *    global lock
    * 3) From the external interface, AcpiReleaseGlobalLock
    *
    ******************************************************************************/
   
   ACPI_STATUS
   AcpiExReleaseMutexObject (
       ACPI_OPERAND_OBJECT     *ObjDesc)
   {
       ACPI_STATUS             Status = AE_OK;
   
   
       ACPI_FUNCTION_TRACE (ExReleaseMutexObject);
   
   
       if (ObjDesc->Mutex.AcquisitionDepth == 0)
       {
           return_ACPI_STATUS (AE_NOT_ACQUIRED);
       }
   
       /* Match multiple Acquires with multiple Releases */
   
       ObjDesc->Mutex.AcquisitionDepth--;
       if (ObjDesc->Mutex.AcquisitionDepth != 0)
       {
           /* Just decrement the depth and return */
   
           return_ACPI_STATUS (AE_OK);
       }
   
       if (ObjDesc->Mutex.OwnerThread)
       {
           /* Unlink the mutex from the owner's list */
   
           AcpiExUnlinkMutex (ObjDesc);
           ObjDesc->Mutex.OwnerThread = NULL;
       }
   
       /* Release the mutex, special case for Global Lock */
   
       if (ObjDesc == AcpiGbl_GlobalLockMutex)
       {
           Status = AcpiEvReleaseGlobalLock ();
       }
       else
       {
           AcpiOsReleaseMutex (ObjDesc->Mutex.OsMutex);
       }
   
       /* Clear mutex info */
   
       ObjDesc->Mutex.ThreadId = 0;
       return_ACPI_STATUS (Status);
   }
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExReleaseMutex
    *
    * PARAMETERS:  ObjDesc             - The object descriptor for this op
    *              WalkState           - Current method execution state
    *
    * RETURN:      Status
    *
    * DESCRIPTION: Release a previously acquired Mutex.
    *
    ******************************************************************************/
   
   ACPI_STATUS
   AcpiExReleaseMutex (
       ACPI_OPERAND_OBJECT     *ObjDesc,
       ACPI_WALK_STATE         *WalkState)
   {
       UINT8                   PreviousSyncLevel;
       ACPI_THREAD_STATE       *OwnerThread;
       ACPI_STATUS             Status = AE_OK;
   
   
       ACPI_FUNCTION_TRACE (ExReleaseMutex);
   
   
       if (!ObjDesc)
       {
           return_ACPI_STATUS (AE_BAD_PARAMETER);
       }
   
       OwnerThread = ObjDesc->Mutex.OwnerThread;
   
       /* The mutex must have been previously acquired in order to release it */
   
       if (!OwnerThread)
       {
           ACPI_ERROR ((AE_INFO,
               "Cannot release Mutex [%4.4s], not acquired",
               AcpiUtGetNodeName (ObjDesc->Mutex.Node)));
           return_ACPI_STATUS (AE_AML_MUTEX_NOT_ACQUIRED);
       }
   
       /* Must have a valid thread ID */
   
       if (!WalkState->Thread)
       {
           ACPI_ERROR ((AE_INFO,
               "Cannot release Mutex [%4.4s], null thread info",
               AcpiUtGetNodeName (ObjDesc->Mutex.Node)));
           return_ACPI_STATUS (AE_AML_INTERNAL);
       }
   
       /*
        * The Mutex is owned, but this thread must be the owner.
        * Special case for Global Lock, any thread can release
        */
       if ((OwnerThread->ThreadId != WalkState->Thread->ThreadId) &&
           (ObjDesc != AcpiGbl_GlobalLockMutex))
       {
           ACPI_ERROR ((AE_INFO,
               "Thread %u cannot release Mutex [%4.4s] acquired by thread %u",
               (UINT32) WalkState->Thread->ThreadId,
               AcpiUtGetNodeName (ObjDesc->Mutex.Node),
               (UINT32) OwnerThread->ThreadId));
           return_ACPI_STATUS (AE_AML_NOT_OWNER);
       }
   
       /*
        * The sync level of the mutex must be equal to the current sync level. In
        * other words, the current level means that at least one mutex at that
        * level is currently being held. Attempting to release a mutex of a
        * different level can only mean that the mutex ordering rule is being
        * violated. This behavior is clarified in ACPI 4.0 specification.
        */
       if (ObjDesc->Mutex.SyncLevel != OwnerThread->CurrentSyncLevel)
       {
           ACPI_ERROR ((AE_INFO,
               "Cannot release Mutex [%4.4s], SyncLevel mismatch: "
               "mutex %u current %u",
               AcpiUtGetNodeName (ObjDesc->Mutex.Node),
               ObjDesc->Mutex.SyncLevel, WalkState->Thread->CurrentSyncLevel));
           return_ACPI_STATUS (AE_AML_MUTEX_ORDER);
       }
   
       /*
        * Get the previous SyncLevel from the head of the acquired mutex list.
        * This handles the case where several mutexes at the same level have been
        * acquired, but are not released in reverse order.
        */
       PreviousSyncLevel =
           OwnerThread->AcquiredMutexList->Mutex.OriginalSyncLevel;
   
       ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,
           "Releasing: Object SyncLevel %u, Thread SyncLevel %u, "
           "Prev SyncLevel %u, Depth %u TID %p\n",
           ObjDesc->Mutex.SyncLevel, WalkState->Thread->CurrentSyncLevel,
           PreviousSyncLevel, ObjDesc->Mutex.AcquisitionDepth,
           WalkState->Thread));
   
       Status = AcpiExReleaseMutexObject (ObjDesc);
       if (ACPI_FAILURE (Status))
       {
           return_ACPI_STATUS (Status);
       }
   
       if (ObjDesc->Mutex.AcquisitionDepth == 0)
       {
           /* Restore the previous SyncLevel */
   
           OwnerThread->CurrentSyncLevel = PreviousSyncLevel;
       }
   
       ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,
           "Released: Object SyncLevel %u, Thread SyncLevel, %u, "
           "Prev SyncLevel %u, Depth %u\n",
           ObjDesc->Mutex.SyncLevel, WalkState->Thread->CurrentSyncLevel,
           PreviousSyncLevel, ObjDesc->Mutex.AcquisitionDepth));
   
       return_ACPI_STATUS (Status);
   }
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExReleaseAllMutexes
    *
    * PARAMETERS:  Thread              - Current executing thread object
    *
    * RETURN:      Status
    *
    * DESCRIPTION: Release all mutexes held by this thread
    *
    * NOTE: This function is called as the thread is exiting the interpreter.
    * Mutexes are not released when an individual control method is exited, but
    * only when the parent thread actually exits the interpreter. This allows one
    * method to acquire a mutex, and a different method to release it, as long as
    * this is performed underneath a single parent control method.
    *
    ******************************************************************************/
   
   void
   AcpiExReleaseAllMutexes (
       ACPI_THREAD_STATE       *Thread)
   {
       ACPI_OPERAND_OBJECT     *Next = Thread->AcquiredMutexList;
       ACPI_OPERAND_OBJECT     *ObjDesc;
   
   
       ACPI_FUNCTION_TRACE (ExReleaseAllMutexes);
   
   
       /* Traverse the list of owned mutexes, releasing each one */
   
       while (Next)
       {
           ObjDesc = Next;
           ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,
               "Mutex [%4.4s] force-release, SyncLevel %u Depth %u\n",
               ObjDesc->Mutex.Node->Name.Ascii, ObjDesc->Mutex.SyncLevel,
               ObjDesc->Mutex.AcquisitionDepth));
   
           /* Release the mutex, special case for Global Lock */
   
           if (ObjDesc == AcpiGbl_GlobalLockMutex)
           {
               /* Ignore errors */
   
               (void) AcpiEvReleaseGlobalLock ();
           }
           else
           {
               AcpiOsReleaseMutex (ObjDesc->Mutex.OsMutex);
           }
   
           /* Update Thread SyncLevel (Last mutex is the important one) */
   
           Thread->CurrentSyncLevel = ObjDesc->Mutex.OriginalSyncLevel;
   
           /* Mark mutex unowned */
   
           Next = ObjDesc->Mutex.Next;
   
           ObjDesc->Mutex.Prev = NULL;
           ObjDesc->Mutex.Next = NULL;
           ObjDesc->Mutex.AcquisitionDepth = 0;
           ObjDesc->Mutex.OwnerThread = NULL;
           ObjDesc->Mutex.ThreadId = 0;
       }
   
       return_VOID;
   }

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