Re: [XEN PATCH] xen/bitmap: remove comment-based deviations

[Jan Beulich <jbeulich@xxxxxxxx>]

On 28.08.2024 15:12, Federico Serafini wrote:
> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> @@ -565,6 +565,10 @@ of this macro do not lead to developer confusion, and 
> can thus be deviated."
>  -config=MC3R1.R20.7,reports+={safe, 
> "any_area(any_loc(any_exp(macro(^count_args_$))))"}
>  -doc_end
>  
> +-doc_begin="The expansion of an argument surrounded by tokens '{', '}' and 
> ';' is safe."
> +-config=MC3R1.R20.7,expansion_context+={safe, 
> "left_right(^[\\{;]$,^[;\\}]$)"}
> +-doc_end

Not the least because this is quite a bit wider than ...

> --- a/xen/include/xen/bitmap.h
> +++ b/xen/include/xen/bitmap.h
> @@ -103,13 +103,10 @@ extern int bitmap_allocate_region(unsigned long 
> *bitmap, int pos, int order);
>  #define bitmap_switch(nbits, zero, small, large)                       \
>       unsigned int n__ = (nbits);                                       \
>       if (__builtin_constant_p(nbits) && !n__) {                        \
> -             /* SAF-7-safe Rule 20.7 non-parenthesized macro argument */ \
>               zero;                                                     \
>       } else if (__builtin_constant_p(nbits) && n__ <= BITS_PER_LONG) { \
> -             /* SAF-7-safe Rule 20.7 non-parenthesized macro argument */ \
>               small;                                                    \
>       } else {                                                          \
> -             /* SAF-7-safe Rule 20.7 non-parenthesized macro argument */ \
>               large;                                                    \
>       }

... what's needed here, I wonder if we're not opening up avenues to
problems by generally permitting that pattern. Plus in the description
I'm missing a statement to the effect of why this is (always) safe.

Jan