IRP_MJ_CLOSE not called

NTDEV
1

I wrote a virtual serial port driver which connects 2 virtual COM-Ports together. 2 User-Application can than write/read to each other.
My Problem is, if I quit the 2 User-Applications that SOMETIMES the last closed Comport receives the IRP_MJ_CLEANUP but after it’s NOT receiving
the IRP_MJ_CLOSE anymore. So I cannot start the last Application again, because the Comport is not free.
This only happens after the 2 Applications transferring greater files (more than 60K).
I have no idea why. On the Cleanup Routine I only cancel all outstanding irp-queues

Thanks for help

U.Koch

2

(1) What is the OS - Virtual Com ports I thought was VXD technology?
(2) If you are working within NT technology - enable verifier.exe to run
and this should help you solve your problem.