macsec: fix negative refcnt on parent link

When creation of a macsec device fails because an identical device
already exists on this link, the current code decrements the refcnt on
the parent link (in ->destructor for the macsec device), but it had not
been incremented yet.

Move the dev_hold(parent_link) call earlier during macsec device
creation.

Fixes: c09440f7dcb3 ("macsec: introduce IEEE 802.1AE driver")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/macsec.c

@@ -3179,6 +3179,8 @@ static int macsec_newlink(struct net *net, struct net_device *dev,
 	if (err < 0)
 		return err;
 
+	dev_hold(real_dev);
+
 	/* need to be already registered so that ->init has run and
 	 * the MAC addr is set
 	 */
@@ -3207,8 +3209,6 @@ static int macsec_newlink(struct net *net, struct net_device *dev,
 
 	macsec_generation++;
 
-	dev_hold(real_dev);
-
 	return 0;
 
 del_dev: