net: introduce IFF_NO_RX_HANDLER

Some network devices - notably ipvlan slave - are not compatible with
any kind of rx_handler. Currently the hook can be installed but any
configuration (bridge, bond, macsec, ...) is nonfunctional.

This change allocates a priv_flag bit to mark such devices and explicitly
forbid installing a rx_handler if such bit is set. The new bit is used
by ipvlan slave device.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ipvlan/ipvlan_main.c

@@ -604,6 +604,8 @@ int ipvlan_link_new(struct net *src_net, struct net_device *dev,
 	 */
 	memcpy(dev->dev_addr, phy_dev->dev_addr, ETH_ALEN);
 
+	dev->priv_flags |= IFF_NO_RX_HANDLER;
+
 	err = register_netdevice(dev);
 	if (err < 0)
 		return err;

include/linux/netdevice.h

@@ -1397,6 +1397,7 @@ struct net_device_ops {
  * @IFF_PHONY_HEADROOM: the headroom value is controlled by an external
  *	entity (i.e. the master device for bridged veth)
  * @IFF_MACSEC: device is a MACsec device
+ * @IFF_NO_RX_HANDLER: device doesn't support the rx_handler hook
  */
 enum netdev_priv_flags {
 	IFF_802_1Q_VLAN			= 1<<0,
@@ -1425,6 +1426,7 @@ enum netdev_priv_flags {
 	IFF_RXFH_CONFIGURED		= 1<<23,
 	IFF_PHONY_HEADROOM		= 1<<24,
 	IFF_MACSEC			= 1<<25,
+	IFF_NO_RX_HANDLER		= 1<<26,
 };
 
 #define IFF_802_1Q_VLAN			IFF_802_1Q_VLAN
@@ -1452,6 +1454,7 @@ enum netdev_priv_flags {
 #define IFF_TEAM			IFF_TEAM
 #define IFF_RXFH_CONFIGURED		IFF_RXFH_CONFIGURED
 #define IFF_MACSEC			IFF_MACSEC
+#define IFF_NO_RX_HANDLER		IFF_NO_RX_HANDLER
 
 /**
  *	struct net_device - The DEVICE structure.

net/core/dev.c

@@ -4351,6 +4351,9 @@ int netdev_rx_handler_register(struct net_device *dev,
 	if (netdev_is_rx_handler_busy(dev))
 		return -EBUSY;
 
+	if (dev->priv_flags & IFF_NO_RX_HANDLER)
+		return -EINVAL;
+
 	/* Note: rx_handler_data must be set before rx_handler */
 	rcu_assign_pointer(dev->rx_handler_data, rx_handler_data);
 	rcu_assign_pointer(dev->rx_handler, rx_handler);