PCI: Fix reference leak in pci_register_host_bridge()

If device_register() fails, call put_device() to give up the reference to
avoid a memory leak, per the comment at device_register().

Found by code review.

Link: https://lore.kernel.org/r/20250225021440.3130264-1-make24@iscas.ac.cn
Fixes: 37d6a0a ("PCI: Add pci_register_host_bridge() interface")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
[bhelgaas: squash Dan Carpenter's double free fix from
https://lore.kernel.org/r/db806a6c-a91b-4e5a-a84b-6b7e01bdac85@stanley.mountain]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org

drivers/pci/probe.c

@@ -953,6 +953,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 	resource_size_t offset, next_offset;
 	LIST_HEAD(resources);
 	struct resource *res, *next_res;
+	bool bus_registered = false;
 	char addr[64], *fmt;
 	const char *name;
 	int err;
@@ -1017,6 +1018,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 	name = dev_name(&bus->dev);
 
 	err = device_register(&bus->dev);
+	bus_registered = true;
 	if (err)
 		goto unregister;
 
@@ -1103,12 +1105,15 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 unregister:
 	put_device(&bridge->dev);
 	device_del(&bridge->dev);
-
 free:
 #ifdef CONFIG_PCI_DOMAINS_GENERIC
 	pci_bus_release_domain_nr(parent, bus->domain_nr);
 #endif
-	kfree(bus);
+	if (bus_registered)
+		put_device(&bus->dev);
+	else
+		kfree(bus);
+
 	return err;
 }