linux-kernel - [PATCH v3 6/7] PCI: endpoint: pci-epf-vntb: Switch vpci_scan_bus() to use pci_scan_root

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Message-ID: <20251130151100.2591822-7-den@valinux.co.jp>
Date: Mon,  1 Dec 2025 00:10:59 +0900
From: Koichiro Den <den@...inux.co.jp>
To: ntb@...ts.linux.dev,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Frank.Li@....com
Cc: jdmason@...zu.us,
	dave.jiang@...el.com,
	allenbh@...il.com,
	mani@...nel.org,
	kwilczynski@...nel.org,
	kishon@...nel.org,
	bhelgaas@...gle.com,
	jbrunet@...libre.com,
	lpieralisi@...nel.org,
	yebin10@...wei.com,
	geert+renesas@...der.be,
	arnd@...db.de,
	stable@...r.kernel.org
Subject: [PATCH v3 6/7] 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.

Signed-off-by: Koichiro Den <den@...inux.co.jp>
---
 drivers/pci/endpoint/functions/pci-epf-vntb.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
index 750a246f79c9..af0651c03b20 100644
--- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
@@ -1098,7 +1098,19 @@ 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;
-- 
2.48.1