mctp: Fix an error handling path in mctp_init()

If mctp_neigh_init() return error, the routes resources should
be released in the error handling path. Otherwise some resources
leak.

Fixes: 4d8b931928 ("mctp: Add neighbour implementation")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Matt Johnston <matt@codeconstruct.com.au>
Link: https://lore.kernel.org/r/20221108095517.620115-1-weiyongjun@huaweicloud.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/mctp/af_mctp.c

@@ -665,12 +665,14 @@ static __init int mctp_init(void)
 
 	rc = mctp_neigh_init();
 	if (rc)
-		goto err_unreg_proto;
+		goto err_unreg_routes;
 
 	mctp_device_init();
 
 	return 0;
 
+err_unreg_routes:
+	mctp_routes_exit();
 err_unreg_proto:
 	proto_unregister(&mctp_proto);
 err_unreg_sock:

net/mctp/route.c

@@ -1400,7 +1400,7 @@ int __init mctp_routes_init(void)
 	return register_pernet_subsys(&mctp_net_ops);
 }
 
-void __exit mctp_routes_exit(void)
+void mctp_routes_exit(void)
 {
 	unregister_pernet_subsys(&mctp_net_ops);
 	rtnl_unregister(PF_MCTP, RTM_DELROUTE);