exmutex.c

acpi tools for linux include acpiexec and acpixtract

/*******************************************************************************
 *
 * 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 ID */

    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 (%d)",
            AcpiUtGetNodeName (ObjDesc->Mutex.Node),
            WalkState->Thread->CurrentSyncLevel));
        return_ACPI_STATUS (AE_AML_MUTEX_ORDER);
    }

    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);
    }

    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 (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)
{
    ACPI_STATUS             Status = AE_OK;


    ACPI_FUNCTION_TRACE (ExReleaseMutex);


    if (!ObjDesc)
    {
        return_ACPI_STATUS (AE_BAD_PARAMETER);
    }

    /* The mutex must have been previously acquired in order to release it */

    if (!ObjDesc->Mutex.OwnerThread)
    {
        ACPI_ERROR ((AE_INFO, "Cannot release Mutex [%4.4s], not acquired",
            AcpiUtGetNodeName (ObjDesc->Mutex.Node)));
        return_ACPI_STATUS (AE_AML_MUTEX_NOT_ACQUIRED);
    }

    /*
     * The Mutex is owned, but this thread must be the owner.
     * Special case for Global Lock, any thread can release
     */
    if ((ObjDesc->Mutex.OwnerThread->ThreadId != WalkState->Thread->ThreadId) &&
        (ObjDesc != AcpiGbl_GlobalLockMutex))
    {
        ACPI_ERROR ((AE_INFO,
            "Thread %X cannot release Mutex [%4.4s] acquired by thread %X",
            WalkState->Thread->ThreadId,
            AcpiUtGetNodeName (ObjDesc->Mutex.Node),
            ObjDesc->Mutex.OwnerThread->ThreadId));
        return_ACPI_STATUS (AE_AML_NOT_OWNER);
    }

    /* 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 sync level of the mutex must be less than or equal to the current
     * sync level
     */
    if (ObjDesc->Mutex.SyncLevel > WalkState->Thread->CurrentSyncLevel)
    {
        ACPI_ERROR ((AE_INFO,
            "Cannot release Mutex [%4.4s], SyncLevel mismatch: mutex %d current %d",
            AcpiUtGetNodeName (ObjDesc->Mutex.Node),
            ObjDesc->Mutex.SyncLevel, WalkState->Thread->CurrentSyncLevel));
        return_ACPI_STATUS (AE_AML_MUTEX_ORDER);
    }

    Status = AcpiExReleaseMutexObject (ObjDesc);

    if (ObjDesc->Mutex.AcquisitionDepth == 0)
    {
        /* Restore the original SyncLevel */

        WalkState->Thread->CurrentSyncLevel = ObjDesc->Mutex.OriginalSyncLevel;
    }
    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_ENTRY ();


    /* Traverse the list of owned mutexes, releasing each one */

    while (Next)
    {
        ObjDesc = Next;
        Next = ObjDesc->Mutex.Next;

        ObjDesc->Mutex.Prev = NULL;
        ObjDesc->Mutex.Next = NULL;
        ObjDesc->Mutex.AcquisitionDepth = 0;

        /* Release the mutex, special case for Global Lock */

        if (ObjDesc == AcpiGbl_GlobalLockMutex)
        {
            /* Ignore errors */

            (void) AcpiEvReleaseGlobalLock ();
        }
        else
        {
            AcpiOsReleaseMutex (ObjDesc->Mutex.OsMutex);
        }

        /* Mark mutex unowned */

        ObjDesc->Mutex.OwnerThread = NULL;
        ObjDesc->Mutex.ThreadId = 0;

        /* Update Thread SyncLevel (Last mutex is the important one) */

        Thread->CurrentSyncLevel = ObjDesc->Mutex.OriginalSyncLevel;
    }
}