Windows System Software -- Consulting, Training, Development -- Unique Expertise, Guaranteed Results

Home NTFSD

Before Posting...

Please check out the Community Guidelines in the Announcements and Administration Category.

More Info on Driver Writing and Debugging


The free OSR Learning Library has more than 50 articles on a wide variety of topics about writing and debugging device drivers and Minifilters. From introductory level to advanced. All the articles have been recently reviewed and updated, and are written using the clear and definitive style you've come to expect from OSR over the years.


Check out The OSR Learning Library at: https://www.osr.com/osr-learning-library/


Frozen minifilter threads unload

Dejan_MaksimovicDejan_Maksimovic Member - All Emails Posts: 636
Hi. Can anyone confirm whether frozen threads (e.g. UWP apps) can hang a minifilter unload for very long times?

We have a situation that looks like it, but no dump or WinDbg access to confirm.

Regards, Dejan.

Comments

  • Dejan_MaksimovicDejan_Maksimovic Member - All Emails Posts: 636
    Anyone from MS, hopefully.
  • Scott_Noone_(OSR)Scott_Noone_(OSR) Administrator Posts: 3,678

    Minifilter unload hangs are usually reference count leaks. Have you tried with Filter Manager Verifier enabled? Should crash at some point and show you what FltMgr is waiting on.

    -scott
    OSR

  • Dejan_MaksimovicDejan_Maksimovic Member - All Emails Posts: 636
    via Email
    Scott,

    This is one in 20 million user machines (and even more unloads), so any
    debugging is a no go :(
    It's not a total hang, it proceeds after some 2-4 hours. I have no other
    clue what might cause something like it (some oplock in a PreOp due to file
    name query being in progress?). But we have seen in our testing frozen
    threads timing us out, only nothing this high.

    We have some logging that shows us objects we use before the unload
    starts (PortDisconnect), and they are all clear. But due to timing/races
    (when "stop filtering" signal is set, some Pre/PostOp could already be in
    progress), some new ones can always pop in that aren't listed.

    Dejan.
Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. Sign in or register to get started.

Upcoming OSR Seminars
OSR has suspended in-person seminars due to the Covid-19 outbreak. But, don't miss your training! Attend via the internet instead!
Kernel Debugging 13-17 May 2024 Live, Online
Developing Minifilters 1-5 Apr 2024 Live, Online
Internals & Software Drivers 11-15 Mar 2024 Live, Online
Writing WDF Drivers 20-24 May 2024 Live, Online