[PATCH net v3] phonet: check register_netdevice_notifier() error in phonet_device_init()

[Minhong He]

phonet_device_init() registers a netdevice notifier before calling
phonet_netlink_register(), but does not check whether notifier
registration succeeded. On failure, netlink setup still proceeds and
init may return success without the notifier in place.

Also, the existing phonet_netlink_register() failure path called
phonet_device_exit(), which runs rtnl_unregister_all() even though
rtnl_register_many() already unwound any partial registration. Calling
the full exit helper on a partial init is not correct.

Check each registration error and unwind only the steps that have
succeeded so far.

Signed-off-by: Minhong He <heminhong@xxxxxxxxxx>
---
v3:
- Use goto-based unwind; do not call phonet_device_exit() on
  phonet_netlink_register() failure (avoids rtnl_unregister_all()
  after rtnl_register_many() already unwound).
- Drop Fixes tag (theoretical init failure path; not suitable for
  stable autosel).
v2: https://lore.kernel.org/netdev/20260716101504.158387-1-heminhong@xxxxxxxxxx/
- On notifier registration failure, unwind only proc/pernet.
v1: https://lore.kernel.org/netdev/20260713075212.431455-1-heminhong@xxxxxxxxxx/

 net/phonet/pn_dev.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c
index ad44831d6745..f41322a12fb7 100644
--- a/net/phonet/pn_dev.c
+++ b/net/phonet/pn_dev.c
@@ -350,16 +350,30 @@ static struct pernet_operations phonet_net_ops = {
 /* Initialize Phonet devices list */
 int __init phonet_device_init(void)
 {
-	int err = register_pernet_subsys(&phonet_net_ops);
+	int err;
+
+	err = register_pernet_subsys(&phonet_net_ops);
 	if (err)
 		return err;
 
 	proc_create_net("pnresource", 0, init_net.proc_net, &pn_res_seq_ops,
 			sizeof(struct seq_net_private));
-	register_netdevice_notifier(&phonet_device_notifier);
+
+	err = register_netdevice_notifier(&phonet_device_notifier);
+	if (err)
+		goto err_pernet;
+
 	err = phonet_netlink_register();
 	if (err)
-		phonet_device_exit();
+		goto err_notifier;
+
+	return 0;
+
+err_notifier:
+	unregister_netdevice_notifier(&phonet_device_notifier);
+err_pernet:
+	unregister_pernet_subsys(&phonet_net_ops);
+	remove_proc_entry("pnresource", init_net.proc_net);
 	return err;
 }
 
-- 
2.25.1