Re: [PATCH v9 5/7] PCI: endpoint: pci-epf-vntb: Reuse pre-exposed doorbells and IRQ flags

[ALOK TIWARI]

On 2/19/2026 1:43 PM, Koichiro Den wrote:
>   static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
>   					    struct pci_epf_bar *db_bar,
>   					    const struct pci_epc_features *epc_features,

The return value of pci_epc_get_features() seems to be used here
without checking for NULL.

Since this function can return NULL, and other EPF drivers
(pci-epf-test.c, pci-epf-ntb.c) handle that case,
is VNTB assuming that epc_features is always non-NULL,
or should a defensive NULL check be added for pci_epc_get_features()?

> @@ -533,9 +549,24 @@ static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
>   	if (ret)
>   		return ret;
>   
> +	/*
> +	 * The doorbell target may already be exposed by a platform-owned fixed
> +	 * BAR. In that case, we must reuse it and the requested db_bar must
> +	 * match.
> +	 */
> +	if (epf->db_msg[0].bar != NO_BAR && epf->db_msg[0].bar != barno) {
> +		ret = -EINVAL;
> +		goto err_free_doorbell;
> +	}
> +
>   	for (req = 0; req < ntb->db_count; req++) {
> +		/* Avoid requesting duplicate handlers */
> +		if (epf_ntb_db_irq_is_duplicated(epf, req))
> +			continue;
> +
>   		ret = request_irq(epf->db_msg[req].virq, epf_ntb_doorbell_handler,
> -				  0, "pci_epf_vntb_db", ntb);
> +		


Thanks,
Alok