igb: 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.

igb 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: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/igb/igb_main.c

@@ -205,10 +205,6 @@ static struct notifier_block dca_notifier = {
 	.priority	= 0
 };
 #endif
-#ifdef CONFIG_NET_POLL_CONTROLLER
-/* for netdump / net console */
-static void igb_netpoll(struct net_device *);
-#endif
 #ifdef CONFIG_PCI_IOV
 static unsigned int max_vfs;
 module_param(max_vfs, uint, 0);
@@ -2881,9 +2877,6 @@ static const struct net_device_ops igb_netdev_ops = {
 	.ndo_set_vf_spoofchk	= igb_ndo_set_vf_spoofchk,
 	.ndo_set_vf_trust	= igb_ndo_set_vf_trust,
 	.ndo_get_vf_config	= igb_ndo_get_vf_config,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller	= igb_netpoll,
-#endif
 	.ndo_fix_features	= igb_fix_features,
 	.ndo_set_features	= igb_set_features,
 	.ndo_fdb_add		= igb_ndo_fdb_add,
@@ -9053,29 +9046,6 @@ static int igb_pci_sriov_configure(struct pci_dev *dev, int num_vfs)
 	return 0;
 }
 
-#ifdef CONFIG_NET_POLL_CONTROLLER
-/* Polling 'interrupt' - used by things like netconsole to send skbs
- * without having to re-enable interrupts. It's not called while
- * the interrupt routine is executing.
- */
-static void igb_netpoll(struct net_device *netdev)
-{
-	struct igb_adapter *adapter = netdev_priv(netdev);
-	struct e1000_hw *hw = &adapter->hw;
-	struct igb_q_vector *q_vector;
-	int i;
-
-	for (i = 0; i < adapter->num_q_vectors; i++) {
-		q_vector = adapter->q_vector[i];
-		if (adapter->flags & IGB_FLAG_HAS_MSIX)
-			wr32(E1000_EIMC, q_vector->eims_value);
-		else
-			igb_irq_disable(adapter);
-		napi_schedule(&q_vector->napi);
-	}
-}
-#endif /* CONFIG_NET_POLL_CONTROLLER */
-
 /**
  *  igb_io_error_detected - called when PCI error is detected
  *  @pdev: Pointer to PCI device