Re: [PATCH v2] xen/hvc: replace BUG_ON() with negative return value

[Juergen Gross]

On 07.07.21 11:57, Jan Beulich wrote:
> On 07.07.2021 11:10, Juergen Gross wrote:
> > Xen frontends shouldn't BUG() in case of illegal data received from
> > their backends. So replace the BUG_ON()s when reading illegal data from
> > the ring page with negative return values.
> >
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> > --- a/drivers/tty/hvc/hvc_xen.c
> > +++ b/drivers/tty/hvc/hvc_xen.c
> > @@ -86,7 +86,11 @@ static int __write_console(struct xencons_info *xencons,
> >   	cons = intf->out_cons;
> >   	prod = intf->out_prod;
> >   	mb();			/* update queue values before going on */
>
> Largely unrelated note: While in general the barriers here may want
> switching to virt_*mb(), this particular one looks to be too heavy
> anyway: a read barrier is all that's needed here afaict, just like
> there's only a write barrier between ring contents and producer
> writing in __write_console().

I agree.

> And btw, since I've got puzzled by the linuxppc-dev@ in the recipients
> list, I did look up relevant entries in ./MAINTAINERS. Shouldn't the
> file be part of "XEN HYPERVISOR INTERFACE"?

I wouldn't mind. Greg, Jiri, what do you think?


Juergen

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