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

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Message-ID: <e21c527b-9f58-25ba-ce00-1bfccf048d1e@redhat.com>
Date:   Fri, 15 Jul 2022 13:24:41 -0700
From:   Tom Rix <trix@...hat.com>
To:     Lyude Paul <lyude@...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 7/15/22 12:09 PM, Lyude Paul wrote:
> 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!

Thanks!

T

>
>> 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;
>>>   }