Re: [PATCH v8 04/12] genirq/affinity: Add cpumask to struct irq_affinity

Thomas Gleixner
2025-09-10T08:22:27Z

On Fri, Sep 05 2025 at 16:59, Daniel Wagner wrote:
> Pass a cpumask to irq_create_affinity_masks as an additional constraint
> to consider when creating the affinity masks. This allows the caller to
> exclude specific CPUs, e.g., isolated CPUs (see the 'isolcpus' kernel
> command-line parameter).
>
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> Signed-off-by: Daniel Wagner <wagi@kernel.org>
> ---
> include/linux/interrupt.h | 16 ++++++++++------
> kernel/irq/affinity.c | 12 ++++++++++--
> 2 files changed, 20 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
> index 51b6484c049345c75816c4a63b4efa813f42f27b..b1a230953514da57e30e601727cd0e94796153d3 100644
> --- a/include/linux/interrupt.h
> +++ b/include/linux/interrupt.h
> @@ -284,18 +284,22 @@ struct irq_affinity_notify {
> * @nr_sets: The number of interrupt sets for which affinity
> * spreading is required
> * @set_size: Array holding the size of each interrupt set
> + * @mask: cpumask that constrains which CPUs to consider when
> + * calculating the number and size of the interrupt sets

You surely couldn't come up with a less descriptive name for this
member, right?

> diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
> index 4013e6ad2b2f1cb91de12bb428b3281105f7d23b..c68156f7847a7920103e39124676d06191304ef6 100644
> --- a/kernel/irq/affinity.c
> +++ b/kernel/irq/affinity.c
> @@ -70,7 +70,13 @@ irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd)
> */
> for (i = 0, usedvecs = 0; i < affd->nr_sets; i++) {
> unsigned int nr_masks, this_vecs = affd->set_size[i];
> - struct cpumask *result = group_cpus_evenly(this_vecs, &nr_masks);
> + struct cpumask *result;
> +
> + if (affd->mask)
> + result = group_mask_cpus_evenly(this_vecs, affd->mask,
> + &nr_masks);

Please get rid of this line break. You have 100 characters.