Re: [PATCH v3] docs/misra: add rule 2.1 exceptions

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 11 Sep 2023, Jan Beulich wrote:
> On 09.09.2023 01:03, Stefano Stabellini wrote:
> > From: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> > 
> > During the discussions that led to the acceptance of Rule 2.1, we
> > decided on a few exceptions that were not properly recorded in
> > rules.rst. Add them now.
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> > Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
> > ---
> > Nicola, does this work with ECLAIR?
> > 
> > I am referring to the locations of the SAF-2-safe tag on top of
> > call_psci_system_off, BUG, etc.
> > 
> > Changes in v3:
> > - added SAF-2-safe to safe.json
> > - added a few SAF-2-safe examples
> > ---
> >  docs/misra/rules.rst    | 13 ++++++++++++-
> >  docs/misra/safe.json    |  8 ++++++++
> >  xen/arch/arm/psci.c     |  1 +
> >  xen/arch/x86/shutdown.c |  1 +
> >  xen/include/xen/bug.h   |  2 ++
> >  5 files changed, 24 insertions(+), 1 deletion(-)
> > 
> > diff --git a/docs/misra/rules.rst b/docs/misra/rules.rst
> > index 34916e266a..82de4c645d 100644
> > --- a/docs/misra/rules.rst
> > +++ b/docs/misra/rules.rst
> > @@ -107,7 +107,18 @@ maintainers if you want to suggest a change.
> >     * - `Rule 2.1 
> > <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_02_01_1.c>`_
> >       - Required
> >       - A project shall not contain unreachable code
> > -     -
> > +     - The following are allowed:
> > +         - Invariantly constant conditions, e.g. 
> > if(IS_ENABLED(CONFIG_HVM)) { S; }
> > +         - Switch with a controlling value statically determined not to
> > +           match one or more case statements
> 
> I (continue to) consider this as too lax. I don't think we want to permit
> something like
> 
> void test(uint8_t val)
> {
>     switch ( val )
>     {
>     case 0x100:
>         ...
> 
> Imo like in the earlier bullet point I think this wants limiting to
> compile-time constant values, at least initially.

Yes good point