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sfc-falcon: remove ndo_poll_controller

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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>
This commit is contained in:
Eric Dumazet 2018-09-27 09:32:00 -07:00 committed by David S. Miller
parent 9447a10ff6
commit a4f570be65
1 changed files with 0 additions and 26 deletions
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26
drivers/net/ethernet/sfc/falcon/efx.c
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@ -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,