ovpn: keep carrier always on for MP interfaces

An ovpn interface configured in MP mode will keep carrier always
on and let the user decide when to bring it administratively up and
down.

This way a MP node (i.e. a server) will keep its interface always
up and running, even when no peer is connected.

Signed-off-by: Antonio Quartulli <[email protected]>
Link: https://patch.msgid.link/[email protected]
Reviewed-by: Sabrina Dubroca <[email protected]>
Tested-by: Oleksandr Natalenko <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

Author: ordex

drivers/net/ovpn/main.c

@@ -93,10 +93,18 @@ static int ovpn_newlink(struct net_device *dev,
 	ovpn->dev = dev;
 	ovpn->mode = mode;
 
-	/* turn carrier explicitly off after registration, this way state is
-	 * clearly defined
+	/* Set carrier explicitly after registration, this way state is
+	 * clearly defined.
+	 *
+	 * In case of MP interfaces we keep the carrier always on.
+	 *
+	 * Carrier for P2P interfaces is initially off and it is then
+	 * switched on and off when the remote peer is added or deleted.
 	 */
-	netif_carrier_off(dev);
+	if (ovpn->mode == OVPN_MODE_MP)
+		netif_carrier_on(dev);
+	else
+		netif_carrier_off(dev);
 
 	return register_netdevice(dev);
 }