Moving from 1.1.2 to 1.2.* causes constant disconnect/connect events

[kmgallahan]

I just spent 6 hours debugging why my serial device was no longer working. There were constant IO exceptions getting thrown, which were triggered by this line:

https://github.com/dotnet/runtime/blob/be6100ed084ced3b5803a6b998c112b85c1a6f64/src/libraries/System.IO.Ports/src/System/IO/Ports/SerialStream.Windows.cs#L899

Which is stated as "(almost impossible to run into)", and even though stepping through in the debugger shows the ReadTimout as 5000 and not equaling SerialPort.InfiniteTimeout, the if condition is still passing, thus resulting in the exception, thus causing this lib to disconnect.

Moving to 1.1.2 makes the problem go away as it doesn't use BaseStream.ReadAsync.

[genemars]

What OS and .net version?

[kmgallahan]

Windows 10 19045.5608 w/ .NET 9

Part of what took so long was thinking it might be a hardware issue. Strangely, it worked fine on my desktop (seemingly, it wasn't immediately failing anyways), but fails on a Surface Pro 7.