Re: [PATCH 1/3] misra: deviate MISRA C Rule 5.5 for 'hypfs_alloc_dyndata'

[Jan Beulich <jbeulich@xxxxxxxx>]

On 25.05.2026 14:05, Dmytro Prokopchuk1 wrote:
> MISRA C Rule 5.5 states: "Identifiers shall be distinct from macro
> names".
> 
> Update ECLAIR configuration to deviate intentional identifier and
> macro name clashes by specifying the macros that should be ignored.
> This includes 'hypfs_alloc_dyndata', where the real function takes
> an allocation size and the same-named macro is a typed convenience
> wrapper that expands calls using sizeof(type).
> 
> Update deviations.rst and rules.rst accordingly.
> 
> Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>

While I'm okay with this approach, were alternatives considered? E.g.
following the xmalloc() naming model, even if that has a name spacing
issue (which ideally we wouldn't further extend)?

> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> @@ -132,6 +132,12 @@ These macros address differences in argument count 
> during compile-time, effectiv
>  
> -config=MC3A2.R5.5,ignored_macros+="name(update_gnttab_par||parse_gnttab_limit)&&loc(file(^xen/common/grant_table\\.c$))"
>  -doc_end
>  
> +-doc_begin="Clash between 'hypfs_alloc_dyndata' function and macro name in 
> 'xen/include/xen/hypfs.h' is deliberate.
> +The function is the allocator taking a size in bytes, while the macro is a 
> typed convenience wrapper used by dynamic
> +hypfs nodes to allocate per-request traversal data with the correct size and 
> return type."
> +-config=MC3A2.R5.5,ignored_macros+="name(hypfs_alloc_dyndata)&&loc(file(^xen/include/xen/hypfs\\.h$))"
> +-doc_end

I think this is too verbose for the purposes here. The details can all
be had ...

> --- a/docs/misra/deviations.rst
> +++ b/docs/misra/deviations.rst
> @@ -176,6 +176,15 @@ Deviations related to MISRA C:2012 Rules:
>         unused 2nd and 3rd parameters to avoid warnings or errors related to 
> them.
>       - ECLAIR has been configured to ignore these macros.
>  
> +   * - R5.5
> +     - Clash between the 'hypfs_alloc_dyndata' function and macro name is
> +       intentional. The function is the allocator taking a size in bytes, 
> while
> +       the macro is a typed convenience wrapper used by dynamic hypfs nodes 
> to
> +       allocate per-request traversal data with the correct size and return 
> type.
> +       The implementation explicitly undefines the macro before defining the 
> real
> +       function, so the name clash is controlled.
> +     - ECLAIR has been configured to ignore this macro.

... from here.

Jan