Re: [PATCH] powerpc/xive: Use cpumask_intersects()

[Michael Ellerman <mpe@ellerman.id.au>]

Costa Shulyupin <costa.shul@redhat.com> writes:
> Replace `cpumask_any_and(a, b) >= nr_cpu_ids`
> with the more readable `!cpumask_intersects(a, b)`.

I agree it's more readable.

It would be nice if the change log told me that both functions have
similar performance behaviour. I'm not saying this is a super hot path,
but CPU masks can get pretty big, and some cpumask routines compute the
full mask while others short-circuit.

cheers

> diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
> index fa01818c1972c..a6c388bdf5d08 100644
> --- a/arch/powerpc/sysdev/xive/common.c
> +++ b/arch/powerpc/sysdev/xive/common.c
> @@ -726,7 +726,7 @@ static int xive_irq_set_affinity(struct irq_data *d,
>  	pr_debug("%s: irq %d/0x%x\n", __func__, d->irq, hw_irq);
>  
>  	/* Is this valid ? */
> -	if (cpumask_any_and(cpumask, cpu_online_mask) >= nr_cpu_ids)
> +	if (!cpumask_intersects(cpumask, cpu_online_mask))
>  		return -EINVAL;
>  
>  	/*
> -- 
> 2.45.0