BSOD when doing multiple isochronous receives

[BruteForce]

We recently uncovered a well hidden bug that is related to isochronous
operations. The way we discovered the bug is by testing ubCore doing
concurrently 8 isochronous receives on some new adapter that supports
8 isochronous DMA channels for receive.

Things would run smoothly at the beginning but after 20-40 minutes of
operation we would get a blue screen of death.

Looking closely at the problem we found out that the bug was not due
to the 8 channels; it was always there (a synchronization issue) but
it was much more unlikely to occur when running less channels. This
means that it can bite you at any moment even with 4 isochronous
receive channels, even if your application has been running flawlessly
for months.

The bug is fixed in ubCore 5.20.

Dimitris Staikos
Unibrain