Re: [PATCH] firmware: arm_scmi: avoid returning uninialized data

[Arnd Bergmann]

On Fri, Feb 16, 2024, at 18:21, Cristian Marussi wrote:
> On Fri, Feb 16, 2024 at 05:32:53PM +0100, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@xxxxxxxx>
>> 
>> Clang notices that there is a code path through
>> scmi_powercap_notify_supported() that returns an
>> undefined value:
>> 
>
> thanks for looking at this, this series that I've just posted is still
> to be reviewd at all, so I would expect issues :D...BUT in this case I
> dont think that the clang report is valid since, inside the culprit
> function scmi_powercap_notify_supported(), a few lines before the
> reported usage of unitialized data there is a check (@line 816) on the
> 'bounds' of evt_id itself
>
> 	if (evt_id >= ARRAY_SIZE(evt_2_cmd) || src_id >= pi->num_domains)
> 		return false;
>
> so basically the mentioned if/else WILL be evaluated in some of its
> branches for sure and supported wont be uninitialized.
>
> Indeed, I removed from here (and from all the series) the explicit
> initialization at definition time right before posting the series.
>
> Having saidm that...maybe it is just brain-dead this approach of mine
> since it is able to fool clang & friends...I would add bACK an explicit
> initialization of supported all across this series in V2, if this
> sounds good to you.

I'm fine with any solution that avoids the warning. I usually
prefer the explicit assignment where it's needed over having
it as part of the declaration, and in this case I would
probably pick a switch/case of a set of if/else fi/else
blocks

     Arnd