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

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 <[email protected]>
Signed-off-by: Koichiro Den <[email protected]>
---
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);
 	if (!vpci_bus) {
 		pr_err("create pci bus failed\n");
 		return -EINVAL;
-- 
2.51.0