[PATCH net-next 4/6] net: rtnetlink: take instance lock inside rtnl_configure_link

[Stanislav Fomichev <sdf.kernel@gmail.com>]

rtnl_configure_link calls __dev_change_flags() and __dev_notify_flags,
both need the instance lock. rtnl_newlink_create grabs it but stacked
devices do not. Move the lock inside rtnl_configure_link.

Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
---
 net/core/rtnetlink.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 12aa3aa1688b..1b7d6f6b8b68 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3660,14 +3660,16 @@ int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm,
 			u32 portid, const struct nlmsghdr *nlh)
 {
 	unsigned int old_flags, changed;
-	int err;
+	int err = 0;
+
+	netdev_lock_ops(dev);
 
 	old_flags = dev->flags;
 	if (ifm && (ifm->ifi_flags || ifm->ifi_change)) {
 		err = __dev_change_flags(dev, rtnl_dev_combine_flags(dev, ifm),
 					 NULL);
 		if (err < 0)
-			return err;
+			goto out;
 	}
 
 	changed = old_flags ^ dev->flags;
@@ -3677,7 +3679,10 @@ int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm,
 	}
 
 	__dev_notify_flags(dev, old_flags, changed, portid, nlh);
-	return 0;
+
+out:
+	netdev_unlock_ops(dev);
+	return err;
 }
 EXPORT_SYMBOL(rtnl_configure_link);
 
@@ -3918,22 +3923,20 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
 		goto out;
 	}
 
-	netdev_lock_ops(dev);
-
 	err = rtnl_configure_link(dev, ifm, portid, nlh);
 	if (err < 0)
 		goto out_unregister;
 	if (tb[IFLA_MASTER]) {
+		netdev_lock_ops(dev);
 		err = do_set_master(dev, nla_get_u32(tb[IFLA_MASTER]), extack);
+		netdev_unlock_ops(dev);
 		if (err)
 			goto out_unregister;
 	}
 
-	netdev_unlock_ops(dev);
 out:
 	return err;
 out_unregister:
-	netdev_unlock_ops(dev);
 	if (ops->newlink) {
 		LIST_HEAD(list_kill);
 
-- 
2.53.0-Meta