ehea: remove ndo_poll_controller

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

ehea uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Douglas Miller <dougmill@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ibm/ehea/ehea_main.c

@@ -921,17 +921,6 @@ static int ehea_poll(struct napi_struct *napi, int budget)
 	return rx;
 }
 
-#ifdef CONFIG_NET_POLL_CONTROLLER
-static void ehea_netpoll(struct net_device *dev)
-{
-	struct ehea_port *port = netdev_priv(dev);
-	int i;
-
-	for (i = 0; i < port->num_def_qps; i++)
-		napi_schedule(&port->port_res[i].napi);
-}
-#endif
-
 static irqreturn_t ehea_recv_irq_handler(int irq, void *param)
 {
 	struct ehea_port_res *pr = param;
@@ -2953,9 +2942,6 @@ static const struct net_device_ops ehea_netdev_ops = {
 	.ndo_open		= ehea_open,
 	.ndo_stop		= ehea_stop,
 	.ndo_start_xmit		= ehea_start_xmit,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller	= ehea_netpoll,
-#endif
 	.ndo_get_stats64	= ehea_get_stats64,
 	.ndo_set_mac_address	= ehea_set_mac_addr,
 	.ndo_validate_addr	= eth_validate_addr,