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 <eduma...@google.com>
Cc: Solarflare linux maintainers <linux-net-driv...@solarflare.com>
Cc: Edward Cree <ec...@solarflare.com>
Cc: Bert Kenward <bkenw...@solarflare.com>
---
drivers/net/ethernet/sfc/falcon/efx.c | 26 --------------------------
1 file changed, 26 deletions(-)
diff --git a/drivers/net/ethernet/sfc/falcon/efx.c
b/drivers/net/ethernet/sfc/falcon/efx.c
index
dd5530a4f8c8936868aed7171bd9481f93730d76..03e2455c502eacd9a4fd5c7fd320a9edcf265f77
100644
--- a/drivers/net/ethernet/sfc/falcon/efx.c
+++ b/drivers/net/ethernet/sfc/falcon/efx.c
@@ -2052,29 +2052,6 @@ static void ef4_fini_napi(struct ef4_nic *efx)
ef4_fini_napi_channel(channel);
}
-/**************************************************************************
- *
- * 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
@@ -2250,9 +2227,6 @@ static const struct net_device_ops ef4_netdev_ops = {
.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,
--
2.19.0.605.g01d371f741-goog
