PCI: Fix reference leak in pci_alloc_child_bus()

If device_register(&child->dev) fails, call put_device() to explicitly
release child->dev, per the comment at device_register().

Found by code review.

Link: https://lore.kernel.org/r/[email protected]
Fixes: 4f53509 ("PCI: Put pci_dev in device tree as early as possible")
Signed-off-by: Ma Ke <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Ilpo Järvinen <[email protected]>
Cc: [email protected]

Author: Ma Ke

drivers/pci/probe.c

@@ -1222,7 +1222,10 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
 add_dev:
 	pci_set_bus_msi_domain(child);
 	ret = device_register(&child->dev);
-	WARN_ON(ret < 0);
+	if (WARN_ON(ret < 0)) {
+		put_device(&child->dev);
+		return NULL;
+	}
 
 	pcibios_add_bus(child);