Re: [PATCH 4/9] ACPI: address violations of MISRA C:2012 Rule 11.8

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 14 Dec 2023, Simone Ballarin wrote:
> From: Maria Celeste Cesario <maria.celeste.cesario@xxxxxxxxxxx>
> 
> The xen sources contain violations of MISRA C:2012 Rule 11.8 whose
> headline states:
> "A conversion shall not remove any const, volatile or _Atomic qualification
> from the type pointed to by a pointer".
> 
> Add missing const qualifiers missing in casting.
> There's no reason to drop the const qualifier in ACPI_COMPARE_NAME since
> the macro arguments are not modified in its body.
> 
> Signed-off-by: Maria Celeste Cesario  <maria.celeste.cesario@xxxxxxxxxxx>
> Signed-off-by: Simone Ballarin  <simone.ballarin@xxxxxxxxxxx>
> ---
>  xen/include/acpi/acmacros.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/xen/include/acpi/acmacros.h b/xen/include/acpi/acmacros.h
> index 86c503c20f..d7c74c5769 100644
> --- a/xen/include/acpi/acmacros.h
> +++ b/xen/include/acpi/acmacros.h
> @@ -116,7 +116,7 @@
>  #define ACPI_PTR_TO_PHYSADDR(i)         ACPI_TO_INTEGER(i)
>  
>  #ifndef ACPI_MISALIGNMENT_NOT_SUPPORTED
> -#define ACPI_COMPARE_NAME(a,b)          (*ACPI_CAST_PTR (u32,(a)) == 
> *ACPI_CAST_PTR (u32,(b)))
> +#define ACPI_COMPARE_NAME(a,b)          (*ACPI_CAST_PTR (const u32,(a)) == 
> *ACPI_CAST_PTR (const u32,(b)))

I am a bit confused but this one. The implementation of ACPI_CAST_PTR
is:

#define ACPI_CAST_PTR(t, p)             ((t *) (acpi_uintptr_t) (p))

The first cast to acpi_uintptr_t would already drop the const anyway?


>  #else
>  #define ACPI_COMPARE_NAME(a,b)          (!ACPI_STRNCMP (ACPI_CAST_PTR 
> (char,(a)), ACPI_CAST_PTR (char,(b)), ACPI_NAME_SIZE))
>  #endif

Would it make sense to also add the const here too if nothing else for
consistency?