netdev - [PATCH net 08/15] ice: remove ndo_poll

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Date:   Fri, 21 Sep 2018 15:27:45 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Michael Chan <michael.chan@...adcom.com>,
        Ariel Elior <ariel.elior@...ium.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Song Liu <songliubraving@...com>,
        Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>
Subject: [PATCH net 08/15] ice: 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.

ice 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@...gle.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---
 drivers/net/ethernet/intel/ice/ice_main.c | 27 -----------------------
 1 file changed, 27 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index f1e80eed2fd6d9f94eab163acb4d178d83ba4af2..3f047bb43348881c592adf3b236518ee21bc2fdd 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -4806,30 +4806,6 @@ void ice_get_stats64(struct net_device *netdev, struct rtnl_link_stats64 *stats)
 	stats->rx_length_errors = vsi_stats->rx_length_errors;
 }
 
-#ifdef CONFIG_NET_POLL_CONTROLLER
-/**
- * ice_netpoll - polling "interrupt" handler
- * @netdev: network interface device structure
- *
- * Used by netconsole to send skbs without having to re-enable interrupts.
- * This is not called in the normal interrupt path.
- */
-static void ice_netpoll(struct net_device *netdev)
-{
-	struct ice_netdev_priv *np = netdev_priv(netdev);
-	struct ice_vsi *vsi = np->vsi;
-	struct ice_pf *pf = vsi->back;
-	int i;
-
-	if (test_bit(__ICE_DOWN, vsi->state) ||
-	    !test_bit(ICE_FLAG_MSIX_ENA, pf->flags))
-		return;
-
-	for (i = 0; i < vsi->num_q_vectors; i++)
-		ice_msix_clean_rings(0, vsi->q_vectors[i]);
-}
-#endif /* CONFIG_NET_POLL_CONTROLLER */
-
 /**
  * ice_napi_disable_all - Disable NAPI for all q_vectors in the VSI
  * @vsi: VSI having NAPI disabled
@@ -5497,9 +5473,6 @@ static const struct net_device_ops ice_netdev_ops = {
 	.ndo_validate_addr = eth_validate_addr,
 	.ndo_change_mtu = ice_change_mtu,
 	.ndo_get_stats64 = ice_get_stats64,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller = ice_netpoll,
-#endif /* CONFIG_NET_POLL_CONTROLLER */
 	.ndo_vlan_rx_add_vid = ice_vlan_rx_add_vid,
 	.ndo_vlan_rx_kill_vid = ice_vlan_rx_kill_vid,
 	.ndo_set_features = ice_set_features,
-- 
2.19.0.444.g18242da7ef-goog