[PATCH] PCI: octep: handle an unsuccessful hotplug scan

[Slavin Liu]

pci_scan_single_device() can return NULL if no device is found or
allocation fails. octep_hp_enable_pdev() passes that pointer to
pci_bus_add_device() and then dereferences it for a debug message.

Return -ENODEV when the scan fails and propagate it through the hotplug
enable_slot callback. This leaves the slot disabled and allows a later
retry without reporting a successful enable to userspace. Log the
failure for callers that cannot return an error to userspace. The
scoped mutex guard releases the slot lock on each return path.

Detected by static analysis and reviewed with AI-assisted source auditing.

Fixes: e434e54d3ffc ("PCI: hotplug: Add OCTEON PCI hotplug controller driver")
Assisted-by: LLM
Signed-off-by: Slavin Liu <bolin.liu@xxxxxxxxxx>
---
 drivers/pci/hotplug/octep_hp.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/hotplug/octep_hp.c b/drivers/pci/hotplug/octep_hp.c
index a0a7f9ccb8fa..a57969185022 100644
--- a/drivers/pci/hotplug/octep_hp.c
+++ b/drivers/pci/hotplug/octep_hp.c
@@ -66,24 +66,31 @@ struct octep_hp_controller {
 	spinlock_t hp_cmd_lock; /* Protects hp_cmd_list */
 };
 
-static void octep_hp_enable_pdev(struct octep_hp_controller *hp_ctrl,
-				 struct octep_hp_slot *hp_slot)
+static int octep_hp_enable_pdev(struct octep_hp_controller *hp_ctrl,
+				struct octep_hp_slot *hp_slot)
 {
 	guard(mutex)(&hp_ctrl->slot_lock);
 	if (hp_slot->hp_pdev) {
 		pci_dbg(hp_slot->hp_pdev, "Slot %s is already enabled\n",
 			hotplug_slot_name(&hp_slot->slot));
-		return;
+		return 0;
 	}
 
 	/* Scan the device and add it to the bus */
 	hp_slot->hp_pdev = pci_scan_single_device(hp_ctrl->pdev->bus,
 						  hp_slot->hp_devfn);
+	if (!hp_slot->hp_pdev) {
+		pci_err(hp_ctrl->pdev, "Failed to scan slot %s\n",
+			hotplug_slot_name(&hp_slot->slot));
+		return -ENODEV;
+	}
 	pci_bus_assign_resources(hp_ctrl->pdev->bus);
 	pci_bus_add_device(hp_slot->hp_pdev);
 
 	dev_dbg(&hp_slot->hp_pdev->dev, "Enabled slot %s\n",
 		hotplug_slot_name(&hp_slot->slot));
+
+	return 0;
 }
 
 static void octep_hp_disable_pdev(struct octep_hp_controller *hp_ctrl,
@@ -109,8 +116,7 @@ static int octep_hp_enable_slot(struct hotplug_slot *slot)
 	struct octep_hp_slot *hp_slot =
 		container_of(slot, struct octep_hp_slot, slot);
 
-	octep_hp_enable_pdev(hp_slot->ctrl, hp_slot);
-	return 0;
+	return octep_hp_enable_pdev(hp_slot->ctrl, hp_slot);
 }
 
 static int octep_hp_disable_slot(struct hotplug_slot *slot)