macvlan: disable LRO on lower device instead of macvlan

A macvlan device has always LRO disabled so that calling
dev_disable_lro() on it does nothing. If we need to disable LRO
e.g. because

  - the macvlan device is inserted into a bridge
  - IPv6 forwarding is enabled for it
  - it is in a different namespace than lowerdev and IPv4
    forwarding is enabled in it

we need to disable LRO on its underlying device instead (as we
do for 802.1q VLAN devices).

v2: use newly introduced netif_is_macvlan()
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -131,6 +131,7 @@
 #include <linux/static_key.h>
 #include <linux/hashtable.h>
 #include <linux/vmalloc.h>
+#include <linux/if_macvlan.h>
 
 #include "net-sysfs.h"
 
@@ -1424,6 +1425,10 @@ void dev_disable_lro(struct net_device *dev)
 	if (is_vlan_dev(dev))
 		dev = vlan_dev_real_dev(dev);
 
+	/* the same for macvlan devices */
+	if (netif_is_macvlan(dev))
+		dev = macvlan_dev_real_dev(dev);
+
 	dev->wanted_features &= ~NETIF_F_LRO;
 	netdev_update_features(dev);