Re: [PATCH v5 4/5] PCI: endpoint: pci-epf-vntb: Switch vpci_scan_bus() to use pci_scan_root_bus()

[Manivannan Sadhasivam]

On Thu, Feb 26, 2026 at 05:41:41PM +0900, Koichiro Den wrote:
> vpci_scan_bus() currently uses pci_scan_bus(), which creates a root bus
> without a parent struct device. In a subsequent change we want to tear
> down the virtual PCI root bus using pci_remove_root_bus(). For that to
> work correctly, the root bus must be associated with a parent device,
> similar to what the removed pci_scan_bus_parented() helper used to do.
> 
> Switch vpci_scan_bus() to use pci_scan_root_bus() and pass
> &ndev->epf->epc->dev as the parent. Build the resource list in the same
> way as pci_scan_bus(), so the behavior is unchanged except that the
> virtual root bus now has a proper parent device. This avoids crashes in
> the pci_epf_unbind() -> epf_ntb_unbind() -> pci_remove_root_bus() ->
> pci_bus_release_domain_nr() path once we start removing the root bus in
> a follow-up patch.
> 
> Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
> Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
> ---
> Changes since v4:
>   - Correct the subject prefix
>     s/NTB: epf: vntb:/PCI: endpoint: pci-epf-vntb:/
> 
>  drivers/pci/endpoint/functions/pci-epf-vntb.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> index 805353528967..f353e9a57194 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> @@ -1220,8 +1220,19 @@ static int vpci_scan_bus(void *sysdata)
>  {
>  	struct pci_bus *vpci_bus;
>  	struct epf_ntb *ndev = sysdata;
> -
> -	vpci_bus = pci_scan_bus(ndev->vbus_number, &vpci_ops, sysdata);
> +	LIST_HEAD(resources);
> +	static struct resource busn_res = {
> +		.start = 0,
> +		.end = 255,
> +		.flags = IORESOURCE_BUS,
> +	};
> +
> +	pci_add_resource(&resources, &ioport_resource);
> +	pci_add_resource(&resources, &iomem_resource);
> +	pci_add_resource(&resources, &busn_res);
> +
> +	vpci_bus = pci_scan_root_bus(&ndev->epf->epc->dev, ndev->vbus_number,
> +				     &vpci_ops, sysdata, &resources);

Don't you need pci_lock_rescan_remove()/pci_unlock_rescan_remove()?

- Mani

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