linux-kernel - Re: [PATCH] drm/nouveau/bios: set info only when the return is not 0

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Message-ID: <44d6fc01654b16f9cdd6b517999ddec76038d547.camel@redhat.com>
Date:   Fri, 15 Jul 2022 15:09:48 -0400
From:   Lyude Paul <lyude@...hat.com>
To:     Tom Rix <trix@...hat.com>, bskeggs@...hat.com, kherbst@...hat.com,
        airlied@...ux.ie, daniel@...ll.ch, nathan@...nel.org,
        ndesaulniers@...gle.com
Cc:     dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH] drm/nouveau/bios: set info only when the return is not 0

On Mon, 2022-07-04 at 17:32 -0400, Lyude Paul wrote:
> Reviewed-by: Lyude Paul <lyude@...hat.com>
> 
> Currently on flakey internet in the back of a car, so I probably won't be
> able
> to push this until I get back tonight or early tomorrow

Whoops! Slipped my mind when I got back, but I just remembered it now so I
will go ahead and push :). apologies for the delay!

> 
> On Sat, 2022-07-02 at 11:39 -0400, Tom Rix wrote:
> > clang static analysis reports
> > drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c:68:17: warning: The right
> > operand of '*' is a garbage value [core.UndefinedBinaryOperatorResult]
> >         switch (!!data * *ver) {
> >                        ^ ~~~~
> > A switch statement with only a default should be reduced to an if.
> > 
> > If nvbios_pmuEp() returns 0, via the data variable, the output info
> > parameter
> > is not used.  So set info only when data is not 0.
> > 
> > The struct nvbios_pmuE only has the type and data elements.  Since both of
> > these
> > are explicitly set, memset is not needed.  So remove it.
> > 
> > Signed-off-by: Tom Rix <trix@...hat.com>
> > ---
> >  drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c | 5 +----
> >  1 file changed, 1 insertion(+), 4 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
> > b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
> > index b4a308f3cf7b..49e2664a734c 100644
> > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
> > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
> > @@ -64,12 +64,9 @@ nvbios_pmuEp(struct nvkm_bios *bios, int idx, u8 *ver,
> > u8
> > *hdr,
> >              struct nvbios_pmuE *info)
> >  {
> >         u32 data = nvbios_pmuEe(bios, idx, ver, hdr);
> > -       memset(info, 0x00, sizeof(*info));
> > -       switch (!!data * *ver) {
> > -       default:
> > +       if (data) {
> >                 info->type = nvbios_rd08(bios, data + 0x00);
> >                 info->data = nvbios_rd32(bios, data + 0x02);
> > -               break;
> >         }
> >         return data;
> >  }
> 

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat