Re: [PATCH] workqueue: validate cpumask_first() result in llc_populate_cpu_shard_id()

[Tejun Heo]

Hello,

On Fri, Apr 10, 2026 at 03:42:00AM -0700, Breno Leitao wrote:
> @@ -8318,7 +8319,17 @@ static void __init llc_populate_cpu_shard_id(const struct cpumask *pod_cpus,
>                          * The siblings' shard MUST be the same as the leader.
>                          * never split threads in the same core.
>                          */
> -                       cpu_shard_id[c] = cpu_shard_id[cpumask_first(sibling_cpus)];
> +                       leader = cpumask_first(sibling_cpus);
> +
> +                       /*
> +                        * sibling_cpus cannot be empty here since 'c'
> +                        * is always set in it. This check silences a
> +                        * compiler warning about using the unchecked
> +                        * cpumask_first() result as an array index.
> +                        */

Can you add more details on the warning and update the patch desc
accordingly? This only triggers on UP configs, right?

Thanks.

-- 
tejun