From: Eric Dumazet <edumazet@google.com>
Date: Thu, 27 Sep 2018 09:32:00 -0700
Subject: sfc-falcon: remove ndo_poll_controller
Patch-mainline: v4.19-rc7
Git-commit: a4f570be654de779eaf626a79c4e0aa5a790505f
References: bsc#1105555 FATE#326117

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.

sfc-falcon 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: Solarflare linux maintainers <linux-net-drivers@solarflare.com>
Cc: Edward Cree <ecree@solarflare.com>
Cc: Bert Kenward <bkenward@solarflare.com>
Acked-By: Bert Kenward <bkenward@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/sfc/falcon/efx.c |   26 --------------------------
 1 file changed, 26 deletions(-)

--- a/drivers/net/ethernet/sfc/falcon/efx.c
+++ b/drivers/net/ethernet/sfc/falcon/efx.c
@@ -2055,29 +2055,6 @@ static void ef4_fini_napi(struct ef4_nic
 
 /**************************************************************************
  *
- * Kernel netpoll interface
- *
- *************************************************************************/
-
-#ifdef CONFIG_NET_POLL_CONTROLLER
-
-/* Although in the common case interrupts will be disabled, this is not
- * guaranteed. However, all our work happens inside the NAPI callback,
- * so no locking is required.
- */
-static void ef4_netpoll(struct net_device *net_dev)
-{
-	struct ef4_nic *efx = netdev_priv(net_dev);
-	struct ef4_channel *channel;
-
-	ef4_for_each_channel(channel, efx)
-		ef4_schedule_channel(channel);
-}
-
-#endif
-
-/**************************************************************************
- *
  * Kernel net device interface
  *
  *************************************************************************/
@@ -2251,9 +2228,6 @@ static const struct net_device_ops ef4_n
 	.ndo_set_mac_address	= ef4_set_mac_address,
 	.ndo_set_rx_mode	= ef4_set_rx_mode,
 	.ndo_set_features	= ef4_set_features,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller = ef4_netpoll,
-#endif
 	.ndo_setup_tc		= ef4_setup_tc,
 #ifdef CONFIG_RFS_ACCEL
 	.ndo_rx_flow_steer	= ef4_filter_rfs,