Re: [RFC PATCH v4 13/28] efi: Update efi_mem_type() to return defined EFI mem types

[Tom Lendacky]

On 2/21/2017 6:05 AM, Matt Fleming wrote:
> On Thu, 16 Feb, at 09:44:57AM, Tom Lendacky wrote:
> > Update the efi_mem_type() to return EFI_RESERVED_TYPE instead of a
> > hardcoded 0.
> >
> > Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> > ---
> >  arch/x86/platform/efi/efi.c |    4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> > index a15cf81..6407103 100644
> > --- a/arch/x86/platform/efi/efi.c
> > +++ b/arch/x86/platform/efi/efi.c
> > @@ -1037,7 +1037,7 @@ u32 efi_mem_type(unsigned long phys_addr)
> >  	efi_memory_desc_t *md;
> >
> >  	if (!efi_enabled(EFI_MEMMAP))
> > -		return 0;
> > +		return EFI_RESERVED_TYPE;
> >
> >  	for_each_efi_memory_desc(md) {
> >  		if ((md->phys_addr <= phys_addr) &&
> > @@ -1045,7 +1045,7 @@ u32 efi_mem_type(unsigned long phys_addr)
> >  				  (md->num_pages << EFI_PAGE_SHIFT))))
> >  			return md->type;
> >  	}
> > -	return 0;
> > +	return EFI_RESERVED_TYPE;
> >  }
>
> I see what you're getting at here, but arguably the return value in
> these cases never should have been zero to begin with (your change
> just makes that more obvious).
>
> Returning EFI_RESERVED_TYPE implies an EFI memmap entry exists for
> this address, which is misleading because it doesn't in the hunks
> you've modified above.
>
> Instead, could you look at returning a negative error value in the
> usual way we do in the Linux kernel, and update the function prototype
> to match? I don't think any callers actually require the return type
> to be u32.

I can do that, I'll change the return type to an int. For the
!efi_enabled I can return -ENOTSUPP and for when an entry isn't
found I can return -EINVAL.  Sound good?

The ia64 arch is the only other arch that defines the function. It
has just a single return 0 that I'll change to -EINVAL.

Thanks,
Tom

>