Re: [PATCH] cpumask: fix integer type in cpumask_first

[Julien Grall <julien@xxxxxxx>]

Hi Stefano,

On 29/09/2023 00:32, Stefano Stabellini wrote:
> nr_cpu_ids is unsigned int, but find_first_bit returns unsigned long (at
> least on arm).
find_* are meant to be used by common code. So I think the first step is 
to correct the return type so it is consistent across all architectures.
I don't have a strong opinion on whether they should all return 
'unsigned long'.
Then we can discuss if the MISRA rule is still violated.

> Use the larger type for min_t to avoid larger-to-smaller
> type assignments. This address 141 MISRA C 10.3 violations.
I find interesting you are saying this given that...
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> ---
>
> diff --git a/xen/include/xen/cpumask.h b/xen/include/xen/cpumask.h
> index 9826707909..a6ed6a28e8 100644
> --- a/xen/include/xen/cpumask.h
> +++ b/xen/include/xen/cpumask.h
> @@ -208,7 +208,7 @@ static inline void cpumask_copy(cpumask_t *dstp, const 
> cpumask_t *srcp)
>   
>   static inline int cpumask_first(const cpumask_t *srcp)
>   {
> -       return min_t(int, nr_cpu_ids, find_first_bit(srcp->bits, nr_cpu_ids));
> +       return min_t(unsigned long, nr_cpu_ids, find_first_bit(srcp->bits, 
> nr_cpu_ids));
... cpumask_first() is return 'int'. So rather than fixing it, you seem 
to have just moved the violation.
>   }
>   
>   static inline int cpumask_next(int n, const cpumask_t *srcp)
Cheers,

--
Julien Grall