linux-kernel - [PATCH 22/23] PCI: Add pbus_validate

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Message-Id: <20251219174036.16738-23-ilpo.jarvinen@linux.intel.com>
Date: Fri, 19 Dec 2025 19:40:35 +0200
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: linux-pci@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Dominik Brodowski <linux@...inikbrodowski.net>,
	linux-kernel@...r.kernel.org
Cc: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH 22/23] PCI: Add pbus_validate_busn() for Bus Number validation

pci_scan_bridge_extend() validates bus numbers but upcoming changes
that separate CardBus code into own function need to call that the
same validation.

Thus, add pbus_validate_busn for validating the Bus Numbers.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---
 drivers/pci/pci.h   |  1 +
 drivers/pci/probe.c | 33 +++++++++++++++++++++------------
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index dbea5db07959..b20ff7ef20ff 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -501,6 +501,7 @@ static inline int pci_resource_num(const struct pci_dev *dev,
 	return resno;
 }
 
+void pbus_validate_busn(struct pci_bus *bus);
 struct resource *pbus_select_window(struct pci_bus *bus,
 				    const struct resource *res);
 void pci_reassigndev_resource_alignment(struct pci_dev *dev);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 1781a0a39f4a..49468644e730 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1314,6 +1314,26 @@ static void pci_enable_rrs_sv(struct pci_dev *pdev)
 
 static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus,
 					      unsigned int available_buses);
+
+void pbus_validate_busn(struct pci_bus *bus)
+{
+	struct pci_bus *upstream = bus->parent;
+	struct pci_dev *bridge = bus->self;
+
+	/* Check that all devices are accessible */
+	while (upstream->parent) {
+		if ((bus->busn_res.end > upstream->busn_res.end) ||
+		    (bus->number > upstream->busn_res.end) ||
+		    (bus->number < upstream->number) ||
+		    (bus->busn_res.end < upstream->number)) {
+			pci_info(bridge, "devices behind bridge are unusable because %pR cannot be assigned for them\n",
+				 &bus->busn_res);
+			break;
+		}
+		upstream = upstream->parent;
+	}
+}
+
 /**
  * pci_ea_fixed_busnrs() - Read fixed Secondary and Subordinate bus
  * numbers from EA capability.
@@ -1579,18 +1599,7 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
 		  (is_cardbus ? "PCI CardBus %04x:%02x" : "PCI Bus %04x:%02x"),
 		  pci_domain_nr(bus), child->number);
 
-	/* Check that all devices are accessible */
-	while (bus->parent) {
-		if ((child->busn_res.end > bus->busn_res.end) ||
-		    (child->number > bus->busn_res.end) ||
-		    (child->number < bus->number) ||
-		    (child->busn_res.end < bus->number)) {
-			dev_info(&dev->dev, "devices behind bridge are unusable because %pR cannot be assigned for them\n",
-				 &child->busn_res);
-			break;
-		}
-		bus = bus->parent;
-	}
+	pbus_validate_busn(child);
 
 out:
 	/* Clear errors in the Secondary Status Register */
-- 
2.39.5