Re: ACPICA regression for empty ResourceTemplates

["Life is hard, and then you die" <ronald@innovation.ch>]

On Tue, Jun 27, 2017 at 11:24:25AM +0200, Lukas Wunner wrote:
> On Tue, Jun 27, 2017 at 01:19:31AM +0000, Zheng, Lv wrote:
> > > On Mon, Jun 26, 2017 at 01:49:03PM +0200, Rafael J. Wysocki wrote:
> > > > On Mon, Jun 26, 2017 at 10:38 AM, Lukas Wunner <lukas@wunner.de> wrote:
> > > > > Hi Robert,
> > > > >
> > > > > ACPICA commit c8eac101 (= Linux commit a83019eb9f1f, "ACPICA: Update
> > > > > resource descriptor handling") is causing a regression when parsing
> > > > > an empty ResourceTemplate:
> > 
> > Can it be fixed by using this logic:
> > if (AmlLength < sizeof (AML_RESOURCE_END_TAG) && AmlLength)
> > Instead of the logic introduced in commit a83019eb9f1f?
> > if (AmlLength < sizeof (AML_RESOURCE_END_TAG))
> 
> Unfortunately not, AmlLength is not 0 but 2 in this case
> (= sizeof(struct aml_resource_end_tag)).

Actually, that will work here (the use of '<' ensures that). But it's
unclear whether this is semantically the correct thing, in particular
because a83019eb9f1f widened the cases where NO_RESOURCE_END_TAG is
returned, but the above suggestion narrows them. Unfortunately commit
a83019eb9f1f is quite vague about why it reverted back to '<='.


  Cheers,

  Ronald