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!wudfext.wudfrefhist

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The !wudfext.wudfrefhist extension displays the reference count stack history for a UMDF object.

!wudfext.wudfrefhist ObjectAddress

Parameters

ObjectAddress
Specifies the address of the UMDF object whose reference count stack history is to be displayed. Note that this is the address of the object itself, not of the interface.

DLL

Wudfext.dll

Additional Information

For more information, see User-Mode Driver Framework Debugging.

Remarks

The !wudfext.wudfrefhist command is not supported by UMDF 1.11.

The ObjectAddress parameter must be the address of the UMDF object, not the address of the interface (which is used by many other UMDF extension commands). To determine the address of the UMDF object, use the !wudfext.wudfdumpobjects command, which displays both the UMDF object address and the interface address. Alternatively, if you know the address of the interface, you can use it as the argument of the !wudfext.wudfobject command, which displays the object address (displayed after the symbol "Fx:").

If the reference count tracking option (TrackRefCounts) has been enabled in WDF Verifier, you can use !wudfext.wudfrefhist to display each call stack that increments or decrements an object's reference count. You can determine whether a call stack is causing a memory leak by examining its AddRef and Release calls for references that are being added and not released.

This command can be used at any time, even if UMDF has not broken in to the debugger.

If this command does not display the desired information, make sure that the relevant data is paged in and then try again.

Here is an example of using the !wudfext.wudfrefhist command:

0:007> !wudfext.umdevstacks
...
      UMDriver Image Path: C:\Windows\System32\drivers\UMDF\WUDFOsrUsbFilter.dll
      Object Tracker Address: 0x0000003792ee9fc0
        Object   Tracking ON
        Refcount Tracking ON

0:007> !wudfext.wudfdumpobjects 0x0000003792ee9fc0
...
WdfTypeIoQueue   Object: 0x0000003792f05ce0, Interface: 0x0000003792f05d58

## 0:007> !wudfext.wudfrefhist 0x0000003792f05ce0
-----------------------------------------------------------------------
## 2  (++)
-----------------------------------------------------------------------
WUDFx!UfxObject::TrackRefCounts+0xb2
WUDFx!CWdfIoQueue::AddRef+0x17adc
WUDFx!CWdfIoQueue::CreateAndInitialize+0xeb
WUDFx!CWdfDevice::CreateIoQueue+0x1e7
WUDFOsrUsbFilter!CMyQueue::Initialize+0x48
WUDFOsrUsbFilter!CMyDevice::Configure+0x7d
WUDFOsrUsbFilter!CMyDriver::OnDeviceAdd+0xca
WUDFx!CWdfDriver::OnAddDevice+0x486
WUDFx!CWUDF::AddDevice+0x43
WUDFHost!CWudfDeviceStack::LoadDrivers+0x320
WUDFHost!CLpcNotification::Message+0x1340
WUDFPlatform!WdfLpcPort::ProcessMessage+0x140
WUDFPlatform!WdfLpcCommPort::ProcessMessage+0x92
WUDFPlatform!WdfLpc::RetrieveMessage+0x20c