linux-kernel - Re: [PATCH V4 3/6] genirq/affinity: Don't pass irq_affinity_desc array to irq_build_affinity

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Message-ID: <60539053-419a-d8e7-79c3-d23c005505b4@oracle.com>
Date:   Wed, 11 Jan 2023 10:16:02 +0000
From:   John Garry <john.g.garry@...cle.com>
To:     Ming Lei <ming.lei@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jens Axboe <axboe@...nel.dk>
Cc:     linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH V4 3/6] genirq/affinity: Don't pass irq_affinity_desc
 array to irq_build_affinity_masks

On 27/12/2022 02:29, Ming Lei wrote:
> Prepare for abstracting irq_build_affinity_masks() into one public helper
> for assigning all CPUs evenly into several groups. Don't pass
> irq_affinity_desc array to irq_build_affinity_masks, instead return
> a cpumask array by storing each assigned group into one element of
> the array.
> 
> This way helps us to provide generic interface for grouping all CPUs
> evenly from NUMA and CPU locality viewpoint, and the cost is one extra
> allocation in irq_build_affinity_masks(), which should be fine since
> it is done via GFP_KERNEL and irq_build_affinity_masks() is called very
> less.
> 
> Reviewed-by: Christoph Hellwig<hch@....de>
> Signed-off-by: Ming Lei<ming.lei@...hat.com>

Reviewed-by: John Garry <john.g.garry@...cle.com>

> ---
>   kernel/irq/affinity.c | 34 ++++++++++++++++++++++++----------
>   1 file changed, 24 insertions(+), 10 deletions(-)
> 
> diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
> index da6379cd27fd..00bba1020ecb 100644
> --- a/kernel/irq/affinity.c
> +++ b/kernel/irq/affinity.c
> @@ -249,7 +249,7 @@ static int __irq_build_affinity_masks(unsigned int startvec,


>   
>    fail_npresmsk:
> @@ -393,7 +398,11 @@ static int irq_build_affinity_masks(unsigned int numvecs,
>   
>    fail_nmsk:
>   	free_cpumask_var(nmsk);
> -	return ret < 0 ? ret : 0;
> +	if (ret < 0) {
> +		kfree(masks);
> +		return NULL;

I dislike non-failure path passing through "fail" labels, but that is 
how the current code is...

> +	}
> +	return masks;
>   }
>