Re: [PATCH v3 3/4] net: mana: Allow irq_setup() to skip cpus for affinity

[Yury Norov]

On Fri, May 09, 2025 at 03:13:45AM -0700, Shradha Gupta wrote:
> In order to prepare the MANA driver to allocate the MSI-X IRQs
> dynamically, we need to prepare the irq_setup() to allow skipping
> affinitizing IRQs to first CPU sibling group.
> 
> This would be for cases when number of IRQs is less than or equal
> to number of online CPUs. In such cases for dynamically added IRQs
> the first CPU sibling group would already be affinitized with HWC IRQ
> 
> Signed-off-by: Shradha Gupta <shradhagupta@xxxxxxxxxxxxxxxxxxx>
> Reviewed-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> ---
>  drivers/net/ethernet/microsoft/mana/gdma_main.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> index 4ffaf7588885..2de42ce43373 100644
> --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> @@ -1288,7 +1288,8 @@ void mana_gd_free_res_map(struct gdma_resource *r)
>  	r->size = 0;
>  }
>  
> -static int irq_setup(unsigned int *irqs, unsigned int len, int node)
> +static int irq_setup(unsigned int *irqs, unsigned int len, int node,
> +		     bool skip_first_cpu)
>  {
>  	const struct cpumask *next, *prev = cpu_none_mask;
>  	cpumask_var_t cpus __free(free_cpumask_var);
> @@ -1303,9 +1304,20 @@ static int irq_setup(unsigned int *irqs, unsigned int len, int node)
>  		while (weight > 0) {
>  			cpumask_andnot(cpus, next, prev);
>  			for_each_cpu(cpu, cpus) {
> +				/*
> +				 * if the CPU sibling set is to be skipped we
> +				 * just move on to the next CPUs without len--
> +				 */
> +				if (unlikely(skip_first_cpu)) {
> +					skip_first_cpu = false;
> +					goto next_cpumask;
> +				}
> +
>  				if (len-- == 0)
>  					goto done;
> +
>  				irq_set_affinity_and_hint(*irqs++, topology_sibling_cpumask(cpu));
> +next_cpumask:
>  				cpumask_andnot(cpus, cpus, topology_sibling_cpumask(cpu));
>  				--weight;
>  			}
> @@ -1403,7 +1415,7 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
>  		}
>  	}
>  
> -	err = irq_setup(irqs, (nvec - start_irq_index), gc->numa_node);
> +	err = irq_setup(irqs, (nvec - start_irq_index), gc->numa_node, false);

What for the 2nd parameter is parenthesized?

>  	if (err)
>  		goto free_irq;
>  
> -- 
> 2.34.1


Reviewed-by: Yury Norov [NVIDIA] <yury.norov@xxxxxxxxx>