Re: [RFC PATCH 0/4] address MISRA C:2012 Rule 15.2

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

On 2023-11-07 11:33, Nicola Vetrini wrote:
> This series is aimed at presenting some strategies that can be used to 
> deal with
> violations of Rule 15.2:
> "The goto statement shall jump to a label declared later in the same 
> function".
> The rule's rationale is about possible developer confusion, therefore 
> it could
> be argued that there is no substantial gain in complying with it, given 
> the
> torough review process in place.
>
> Nonetheless, the proposed resolution strategies are the following:
> - use a loop instead of a goto (see patch 1 and 3)
> - make the jump due to the goto forward, rather than backward (see 
> patch 2)
> - unconditionally allow certain constructs, such as "goto retry", whose 
> presence
>   in the codebase typically signifies that all other reasonable 
> approaches (e.g,
>   loops, forward jumps) have been considered and deemed inferior in 
> terms of
>   code readability.
>
> The latter strategy may be postponed until all goto-s with a certain 
> label have
> been examined. An alternative strategy could be to allow certain files
> (most notably those under x86/x86_emulate) to have backward jumps, and 
> resolve
> the remaining violations.
>
> Any feedback on this matter is welcome.
>
> Nicola Vetrini (4):
>   xen/vsprintf: replace backwards jump with loop
>   x86/dom0: make goto jump forward
>   xen/arm: GICv3: address MISRA C:2012 Rule 15.2
>   automation/eclair: add deviation for certain backwards goto
>
>  .../eclair_analysis/ECLAIR/deviations.ecl     | 10 +++
>  docs/misra/deviations.rst                     | 10 +++
>  xen/arch/arm/gic-v3-its.c                     | 81 ++++++++++---------
>  xen/arch/x86/dom0_build.c                     | 14 ++--
>  xen/common/vsprintf.c                         | 20 +++--
>  5 files changed, 81 insertions(+), 54 deletions(-)
Cc: all involved maintainers

In concert with Stefano, and given the feedback received on this RFC 
series, it has been decided to deviate globally this rule, on the 
grounds that there are already guidelines on the usage of goto-s within 
Xen, so it was deemed not worth pursuing the resolution of these 
violations. Therefore, the patches contained here can be ignored for the 
purposes of MISRA compliance.
--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)