On Fri, 17 Jan 2025 17:33:31 -0700 Ahmed Zaki wrote:
> +#ifdef CONFIG_RFS_ACCEL
> +static void
> +netif_irq_cpu_rmap_notify(struct irq_affinity_notify *notify,
> + const cpumask_t *mask)
> +{
> + struct napi_struct *napi =
> + container_of(notify, struct napi_struct, notify);
> + struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
> + int err;
> +
> + if (napi->dev->rx_cpu_rmap_auto) {
Can this ever not be true?
> + err = cpu_rmap_update(rmap, napi->napi_rmap_idx, mask);
> + if (err)
> + pr_warn("%s: RMAP update failed (%d)\n",
> + __func__, err);
netdev_warn(napi->dev, "...) ?
> + }
> +}
> +
> +static void netif_napi_affinity_release(struct kref *ref)
> +{
> + struct napi_struct *napi =
> + container_of(ref, struct napi_struct, notify.kref);
> + struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
> +
> + if (!napi->dev->rx_cpu_rmap_auto)
Similar question, can it possibly be false without driver bugs?
I think you disable rmap completely if we can't add a single IRQ,
that may be too drastic. Better miss one IRQ than the whole rmap, no?
> + return;
> + rmap->obj[napi->napi_rmap_idx] = NULL;
> + napi->napi_rmap_idx = -1;
Why do we modify NAPI here? Shouldn't caller be responsible for this?
> + cpu_rmap_put(rmap);
> +}
> +
> +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 (!rmap)
Should never happen, I'd ignore this and let the kernel crash below.
> + return -EINVAL;
> +
> + 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;
> + napi->napi_rmap_idx = -1;
> +err_add:
> + cpu_rmap_put(rmap);
> + return rc;
> +}
