UMDF 1.9 Issue: Refcount on Continuous reader should be 0

Question

I'm trying to fix an old issue in a UMDF version 1.9 package and I'm hoping someone here can assist. During Pnp Remove we observe the following error message in the Windows Debugger:

**** WUDF DriverStop - Internal error 0x500000000000000
**** in Host
**** drivers\wdf\umdf\driverhost\framework\v1\wudf\wdfusbpipe.cpp:210(CWdfUsbPipeContinuousReader::~CWdfUsbPipeContinuousReader):
Refcount on Continuous reader should be  0, Context Record: .cxr 0x000000739857D810

From my undestanding of the documentation, the DLL is implementing the Continous Reader state management correctly. I have verified IWDFIoTargetStateManagement::Start is called during  IPnpCallback::OnD0Entry and that IWDFIoTargetStateManagement::Stop is called during  IPnpCallback::OnD0Exit and that references acquired for the callback completion and failure routines have been ->Release()'d. 

I have used WdfVerifier to enable Object and Refernce countr tracking and at the point where the debugger breaks, I can see that there are several objects still allocated by the DLL, but none of these appear to be the Continuous Reader itself

0:007> !wudfext.wudfdumpobjects 0x0000025515794fc0
WdfTypeDriver	Object: 0x0000025515796f60, Interface: 0x0000025515796fd8
WdfTypeDevice	Object: 0x00000255157afc70, Interface: 0x00000255157afce8
WdfTypeIoTarget	Object: 0x00000255157bbeb0, Interface: 0x00000255157bbf28
WdfTypeCmResourceList	Object: 0x00000255157c6f20, Interface: 0x00000255157c6f98
WdfTypeCmResourceList	Object: 0x00000255157cef20, Interface: 0x00000255157cef98
WdfTypeIoQueue	Object: 0x00000255157f1ce0, Interface: 0x00000255157f1d58
WdfTypeIoQueue	Object: 0x00000255157ffce0, Interface: 0x00000255157ffd58
WdfTypeIoTarget	Object: 0x0000025515838e90, Interface: 0x0000025515838f08
WdfTypeFile	Object: 0x0000025515843f40, Interface: 0x0000025515843fb8
WdfTypeUsbInterface	Object: 0x00000255158cbf40, Interface: 0x00000255158cbfb8
WdfTypeRequest	Object: 0x00000255158d6e20, Interface: 0x00000255158d6e98
WdfTypeIoTarget	Object: 0x000002551595be80, Interface: 0x000002551595bef8
WdfTypeIoTarget	Object: 0x00000255159d1e80, Interface: 0x00000255159d1ef8
WdfTypeIoTarget	Object: 0x0000025515a47e80, Interface: 0x0000025515a47ef8
WdfTypeRequest	Object: 0x0000025515c07e20, Interface: 0x0000025515c07e98
WdfTypeMemoryObject	Object: 0x0000025515e32f60, Interface: 0x0000025515e32fd8

I'm assuming an incorrect reference count on one of these objects is causing the error message displayed above to appear and preventing the ~CMyDevice() destructor from being called. But I'm at a bit of a loss to figure out which object from the list above is problematic? If anyone can suggest how to proceed I would appreciate it. 

Answer 1

UMDF v1 is in maintenance mode since few releases of Windows now. You should consider upgrading to UMDF v2. As noted in the docs:

UMDF 2 is the latest version of UMDF and supersedes UMDF 1. All new UMDF drivers should be written using UMDF 2. No new features are being added to UMDF 1 and there is limited support for UMDF 1 on newer versions of Windows 10. Universal Windows drivers must use UMDF 2. For more info, see Getting Started with UMDF.

That said, couple of suggestions:

1. You can review this sample driver below that shows how to configure the continuous reader and also review the ref counts associated with the USB target pipe
   https://github.com/microsoft/Windows-driver-samples/blob/6c1981b8504329521343ad00f32daa847fa6083a/usb/umdf_fx2/driver/Device.cpp
2. You can review the references associated with the IWDFUsbTargetPipe associated with the continuous reader (where you called ConfigureContinuousReader) using the debugger extension command  !wudfext.wudfrefhist

Answer 2

Thanks for your suggestion Shyamal, it was quite helpful to track down the issue. Turns out we were missing a call to DeleteWdfObject() on the IWDFUsbTargetDevice.