um: add netpoll support

To make netconsole usable on UML, its ethernet driver needs netpoll
support.
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/drivers/net_kern.c

@@ -262,6 +262,15 @@ static int uml_net_change_mtu(struct net_device *dev, int new_mtu)
 	return 0;
 }
 
+#ifdef CONFIG_NET_POLL_CONTROLLER
+static void uml_net_poll_controller(struct net_device *dev)
+{
+	disable_irq(dev->irq);
+	uml_net_interrupt(dev->irq, dev);
+	enable_irq(dev->irq);
+}
+#endif
+
 static void uml_net_get_drvinfo(struct net_device *dev,
 				struct ethtool_drvinfo *info)
 {
@@ -364,6 +373,9 @@ static const struct net_device_ops uml_netdev_ops = {
 	.ndo_set_mac_address	= eth_mac_addr,
 	.ndo_change_mtu 	= uml_net_change_mtu,
 	.ndo_validate_addr	= eth_validate_addr,
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	.ndo_poll_controller = uml_net_poll_controller,
+#endif
 };
 
 /*