rtnetlink: allow to register ops without ops->setup set

So far, it is assumed that ops->setup is filled up. But there might be
case that ops might make sense even without ->setup. In that case,
forbid to newlink and dellink.

This allows to register simple rtnl link ops containing only ->kind.
That allows consistent way of passing device kind (either device-kind or
slave-kind) to userspace.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/dev.c b/net/core/dev.c
index de9774119541213e7c77729eb9a438a5e23ace0d..6e2a2cd8232199b2ff15502cdcb4f761f3c52136 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7091,7 +7091,7 @@ static void __net_exit default_device_exit_batch(struct list_head *net_list)
        rtnl_lock_unregistering(net_list);
        list_for_each_entry(net, net_list, exit_list) {
                for_each_netdev_reverse(net, dev) {
-                       if (dev->rtnl_link_ops)
+                       if (dev->rtnl_link_ops && dev->rtnl_link_ops->dellink)
                                dev->rtnl_link_ops->dellink(dev, &dev_kill_list);
                        else
                                unregister_netdevice_queue(dev, &dev_kill_list);

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 1063996f8317fb95fea964e095ae2e372ceb74be..27acaf7ff6d7e6914ad3ef62d4e5be7e22ddfc64 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -299,7 +299,12 @@ int __rtnl_link_register(struct rtnl_link_ops *ops)
        if (rtnl_link_ops_get(ops->kind))
                return -EEXIST;
 
-       if (!ops->dellink)
+       /* The check for setup is here because if ops
+        * does not have that filled up, it is not possible
+        * to use the ops for creating device. So do not
+        * fill up dellink as well. That disables rtnl_dellink.
+        */
+       if (ops->setup && !ops->dellink)
                ops->dellink = unregister_netdevice_queue;
 
        list_add_tail(&ops->list, &link_ops);
@@ -1777,7 +1782,7 @@ static int rtnl_dellink(struct sk_buff *skb, struct nlmsghdr *nlh)
                return -ENODEV;
 
        ops = dev->rtnl_link_ops;
-       if (!ops)
+       if (!ops || !ops->dellink)
                return -EOPNOTSUPP;
 
        ops->dellink(dev, &list_kill);
@@ -2038,6 +2043,9 @@ replay:
                        return -EOPNOTSUPP;
                }
 
+               if (!ops->setup)
+                       return -EOPNOTSUPP;
+
                if (!ifname[0])
                        snprintf(ifname, IFNAMSIZ, "%s%%d", ops->kind);