Re: [PATCH v3] ACPI: scan: Avoid registering platform devices with resource overlaps

On Sat, Aug 8, 2026 at 10:04 PM Andy Shevchenko
<[email protected]> wrote:
>
> On Fri, Aug 07, 2026 at 12:22:37PM +0200, Rafael J. Wysocki wrote:
>
> > If acpi_dev_get_resources() returns overlapping I/O or memory resources,
> > the subsequent registration of a platform device will fail with -EBUSY
> > due to a resource conflict.  This is reported to happen on Acer Aspire
> > ES1-572 [1].
> >
> > Avoid that by adjusting resources returned by acpi_dev_get_resources()
> > to eliminate partial overlaps between them.
> >
> > This has not been regarded as necessary before because putting
> > overlapping resources into the _CRS of one device is really pointless,
> > but now that the issue has been reported to actually happen in the
> > field, it needs to be done.
>
> ...
>
> >    * Use resource_union() and adjust code and comment (Andy)
>
> Thanks, LGTM now,
> Reviewed-by: Andy Shevchenko <[email protected]>

Thanks!

> > +static unsigned int acpi_platform_adjust_resources(struct acpi_device *adev,
> > +                                                struct resource *new_res,
> > +                                                struct resource *resources,
> > +                                                unsigned int count)
> > +{
> > +     unsigned int i;
> > +
> > +     if (!(new_res->flags & (IORESOURCE_IO | IORESOURCE_MEM)))
>
> Can also be
>
>         if (!(resource_type(new_res) & (IORESOURCE_IO | IORESOURCE_MEM)))

It could, but it would add a redundant "bitwise and" with the type mask.

I guess the compiler can be expected to optimize it away, but if it
doesn't get optimized away, it's just pure useless overhead.

> > +             return count;
> > +
> > +     for (i = 0; i < count; ) {
> > +             struct resource *res = &resources[i];
>
> > +             if (resource_type(new_res) != resource_type(res) ||
> > +                 !resource_union(new_res, res, new_res)) {
>
> Wondering why we don't have the resource type checks in resource_overlaps(),

Yeah, it looks like a missing piece.

> but we have in resource_contains(). Ilpo, do you know?