Re: [PATCH 5/6] scsi: remove stale BusLogic driver

Arnd Bergmann
2022-06-06T15:00:44Z

On Mon, Jun 6, 2022 at 12:40 PM Maciej W. Rozycki <macro@orcam.me.uk> wrote:
>
> On Mon, 6 Jun 2022, Arnd Bergmann wrote:
>
> > This was in turn fixed in commit 56f396146af2 ("scsi: BusLogic: Fix
> > 64-bit system enumeration error for Buslogic"), 8 years later.
> >
> > The fact that this was found at all is an indication that there are
> > users, and it seems that Maciej, Matt and Khalid all have access to
> > this hardware, but if it took eight years to find the problem,
> > it's likely that nobody actually relies on it.
>
> Umm, I use it with a 32-bit system, so it would be quite an issue for me
> to discover a problem with 64-bit configurations. And I quite rely on
> this system for various stuff too!

Ok, good to know.

> > Remove it as part of the global virt_to_bus()/bus_to_virt() removal.
> > If anyone is still interested in keeping this driver, the alternative
> > is to stop it from using bus_to_virt(), possibly along the lines of
> > how dpt_i2o gets around the same issue.
>
> Thanks for the pointer and for cc-ing me. Please refrain from removing
> the driver at least for this release cycle and let me fix it.

Sure, no problem. It looks like I forgot to actually Cc you on the series
as I had meant to, glad it reached you anyway.

> It should be easy to mimic what I did for the defza driver: all bus addresses in
> the DMA API come associated with virtual addresses, so it is just a matter of
> recording those somewhere for later use rather than trying to mess up with
> bus addresses to figure out a reverse mapping.

I looked at the defza driver and that one appears simpler to me, as you
can look up the virtual address from an index, but it's possible I missed
what you do here. I meant specifically the calculation added by commit
67af2b060e02 ("[SCSI] dpt_i2o: move from virt_to_bus/bus_to_virt
to dma_alloc_coherent") in the dpt_i2o driver that can be used to
compute the virtual address. If something simpler works as well, that
is of course better.

Arnd