eventqueueum.cpp

Go to the documentation of this file.

/*++
 
Copyright (c) Microsoft. All rights reserved.
 
Module Name:
 
    EventQueueUm.cpp
 
Abstract:
 
    This module implements user mode specific functionality of event queue
 
    This functionality needed to be separated out since the KM portion takes
    a reference on driver object because KM MxWorkItem::_Free does not wait for
    callback to return (i.e. rundown synchronously).
 
    MxWorkItem::_Free in UM currently waits for callback to return (i.e. runs
    down synchronously) hence does not need a reference on driver/devstack
    object (see comments on top of MxWorkItemUm.h file).
 
    In future if UM work-item is made similar to km workitem, UMDF may need to
    ensure that modules stay loaded, though the mechanism to ensure that would
    likely be different from a reference on the driver. It would likely be a
    reference on the devicestack object.
 
Environment:
 
    User mode only
 
Revision History:
 
 
 
 
--*/
 
#include "pnppriv.hpp"
 
VOID
FxWorkItemEventQueue::QueueWorkItem(
    VOID
    )
{
    //
    // In user mode WorkItem::_Free waits for workitem callbacks to return
    // So we don't need outstanding reference on driver object or the devstack
    //
 
    m_WorkItem.Enqueue(
        (PMX_WORKITEM_ROUTINE) _WorkItemCallback,
        (FxEventQueue*) this);
}
 
VOID
FxWorkItemEventQueue::_WorkItemCallback(
    __in MdDeviceObject DeviceObject,
    __in PVOID Context
    )
/*++
 
Routine Description:
    This is the work item that attempts to run the machine on a thread
    separate from the one the caller was using.  It implements step 9 above.
 
--*/
{
    FxWorkItemEventQueue* This = (FxWorkItemEventQueue*) Context;
 
    UNREFERENCED_PARAMETER(DeviceObject);
 
    //
    // In user mode WorkItem::_Free waits for workitem callbacks to return
    // So we don't need outstanding reference on driver object
    //
 
    This->EventQueueWorker();
}