Re: [Intel-gfx] [PATCH 2/3] drm/i915: split out check for noncontiguous pfn range

From: Chris Wilson
Date: Tue Mar 21 2017 - 06:23:48 EST


On Tue, Mar 21, 2017 at 09:56:52AM +0000, Chris Wilson wrote:
> On Mon, Mar 20, 2017 at 10:40:28AM +0100, Arnd Bergmann wrote:
> > We get a warning with gcc-7 about a pointless comparison when
> > using a linear memmap:
> >
> > drivers/gpu/drm/i915/selftests/scatterlist.c: In function 'alloc_table':
> > drivers/gpu/drm/i915/selftests/scatterlist.c:219:66: error: self-comparison always evaluates to false [-Werror=tautological-compare]
> >
> > Splitting out the comparison into a separate function avoids the warning
> > and makes it slightly more obvious what happens.
>
> I worried whether gcc will simply get smarter and apply its warning more
> consistently, but I agree the helper is good documentation.
>
> > Fixes: 935a2f776aa5 ("drm/i915: Add some selftests for sg_table manipulation")
> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>

And applied.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre