Re: [PATCH net 10/11] sfc-falcon: remove ndo_poll_controller
From: Bert Kenward <hidden>
Date: 2018-09-28 13:52:54
On 27/09/18 17:32, Eric Dumazet wrote:
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 <redacted> Cc: Edward Cree <redacted> Cc: Bert Kenward <redacted>
Acked-By: Bert Kenward <redacted>
quoted hunk ↗ jump to hunk
--- 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,