I still think your requirement is odd and that there is probably saome other
way to accomplish your goal. However, walking the attached device link is
not safe as the OS provides no synchronization mechanism for you to use to
access this link. You might be able to safely make an assumption regarding
the safety of traversing this link based on the current PnP IRP you are
processing, but without source code review of the relevant NT OS modules it
will be difficult to validate your assumptions. You could of course enforce
safety through extreme measures, but once again I really think you should
consider other options.
=====================
Mark Roddy
Hollis Technology Solutions
www.hollistech.com
xxxxx@hollistech.com
-----Original Message-----
From: Vijay Agrawal [mailto:xxxxx@veritas.com]
Sent: Tuesday, July 22, 2003 6:40 AM
To: Windows System Software Developers Interest List
Subject: [ntdev] Re: Finding out the Attached Upper device object fromPDO
Hi Thanks for the comments,
Re:"
Okay, so you want to find out if a given driver is already in the stack at
the time your AddDevice is running. If that other driver belongs to you, and
if you believe that every other driver between you and it will pass down
unrecognized IRP_MJ_INTERNAL_DEVICE_CONTROL requests, you could define one
of those to “ping” that other driver. Alternatively, you could issue an
IRP_MN_QUERY_INTERFACE that your other driver would recognize."
Problem is the other driver is third party driver. In that case we do not
have anything as you mentioned above. Re:“This is still a fairly unusual
requirement. Why can’t you do this at setup time by having a program, like a
co-installer DLL, query the UpperFilters or LowerFilters values for the
device and the class to see if a particular service name is in the list?”
Because the other driver is not a Upper or Lower Filter. It replaces some
class driver in such a way that few devices configured under driver X and
rest are configured under Y. Requirement is in my filter I do not want to
attach to the objects which are configured under X.
Regards,
Vijay
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