Subject: Re: [PATCH net-next v4 2/6] net: napi: add internal ARFS rmap management

From: Simon Horman <[email-masked]>
Date: Fri, 10 Jan 2025 11:55:48 +0000

On Thu, Jan 09, 2025 at 04:31:03PM -0700, Ahmed Zaki wrote:
> For drivers using the netif_enable_cpu_rmap(), move the IRQ rmap notifier
> inside the napi_struct.
> 
> Signed-off-by: Ahmed Zaki <[email-masked]>

...

> diff --git a/net/core/dev.c b/net/core/dev.c

...

> +static int napi_irq_cpu_rmap_add(struct napi_struct *napi, int irq)
> +{
> +	struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
> +	int rc;
> +
> +	if (!napi || !rmap)
> +		return -EINVAL;

Hi Ahmed,

Here it is assumed that napi may be NULL.  But it is dereferenced
unconditionally on the first like of this function.

Flagged by Smatch.

> +	napi->notify.notify = netif_irq_cpu_rmap_notify;
> +	napi->notify.release = netif_napi_affinity_release;
> +	cpu_rmap_get(rmap);
> +	rc = cpu_rmap_add(rmap, napi);
> +	if (rc < 0)
> +		goto err_add;
> +
> +	napi->napi_rmap_idx = rc;
> +	rc = irq_set_affinity_notifier(irq, &napi->notify);
> +	if (rc)
> +		goto err_set;
> +
> +	return 0;
> +
> +err_set:
> +	rmap->obj[napi->napi_rmap_idx] = NULL;
> +err_add:
> +	cpu_rmap_put(rmap);
> +	return rc;
> +}
>  #endif
>  
>  void netif_napi_set_irq(struct napi_struct *napi, int irq)

...

-- 
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