Re: [XEN PATCH 2/2] xen/cpu: address MISRA C Rule 17.7

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 26 Feb 2024, Jan Beulich wrote:
> On 23.02.2024 10:35, Nicola Vetrini wrote:
> > Refactor cpu_notifier_call_chain into two functions:
> > - the variant that is allowed to fail loses the nofail flag
> > - the variant that shouldn't fail is encapsulated in a call
> >   to the failing variant, with an additional check.
> > 
> > This prevents uses of the function that are not supposed to
> > fail from ignoring the return value, thus violating Rule 17.7:
> > "The value returned by a function having non-void return type shall
> > be used".
> > 
> > No functional change.
> > 
> > Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
> 
> I'm afraid I disagree with this kind of bifurcation. No matter what
> Misra thinks or says, it is normal for return values of functions to
> not always be relevant to check.

Hi Jan, I disagree.

Regardless of MISRA, I really think return values need to be checked.
Moreover, we decided as a group to honor MISRA Rule 17.7, which requires
return values to be checked. This patch is a good step forward.


> To deal with the Misra rule imo requires to first have an abstract
> plan of how to handle such globally in the code base. Imo such a plan
> can't be to introduce perhaps dozens of new wrapper functions like is
> done here.

This patch is following the right pattern, one we already follow with
the _locked suffix.