How to replace set_fs(KERNEL_DS) for a kernel 5.10.x module driver version

[Greg KH]

On Tue, Jan 12, 2021 at 09:55:01AM +0000, Jorge Fernandez Monteagudo wrote:
> >Patents have almost nothing to do with licenses, we have many things in
> >the Linux kernel that are under a GPLv2 license that have patents issued
> >for (and are actively enforced.)  The GPL can, and does, work with the
> >patent system, so if that's a reason that any company tries to give for
> >not releasing kernel code, it's very misinformed.
> 
> Well, I think the only the reason not to publish the code was because
> it's a driver for a custom hardware with no interest outside our
> department...

Doesn't matter, we take drivers for anything, as long as someone is
using the hardware.

> > Anyway, off-topic but I figured I would try to clear that up.
> 
> I was wondering that with the current limitation, there is no way to
> call functions in a driver as the cdc-acm from other drivers as the
> dummy I sent. Maybe our driver was designed the way is to avoid
> latencies from context switching if the code were in userspace... It's
> only a guess...

You are dealing with USB speeds and latencies, kernel syscall issues are
the least of your worries here.

thanks,

greg k-h