netdev - [PATCH net 04/15] ixgbevf: remove ndo_poll

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Date:   Fri, 21 Sep 2018 15:27:41 -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 04/15] ixgbevf: 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.

ixgbevf 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>
---
 .../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 21 -------------------
 1 file changed, 21 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
index d86446d202d5ed95826db225139b095d7c7a683c..5a228582423b74726de2bd040a388eb8e59df764 100644
--- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
+++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
@@ -4233,24 +4233,6 @@ static int ixgbevf_change_mtu(struct net_device *netdev, int new_mtu)
 	return 0;
 }
 
-#ifdef CONFIG_NET_POLL_CONTROLLER
-/* Polling 'interrupt' - used by things like netconsole to send skbs
- * without having to re-enable interrupts. It's not called while
- * the interrupt routine is executing.
- */
-static void ixgbevf_netpoll(struct net_device *netdev)
-{
-	struct ixgbevf_adapter *adapter = netdev_priv(netdev);
-	int i;
-
-	/* if interface is down do nothing */
-	if (test_bit(__IXGBEVF_DOWN, &adapter->state))
-		return;
-	for (i = 0; i < adapter->num_rx_queues; i++)
-		ixgbevf_msix_clean_rings(0, adapter->q_vector[i]);
-}
-#endif /* CONFIG_NET_POLL_CONTROLLER */
-
 static int ixgbevf_suspend(struct pci_dev *pdev, pm_message_t state)
 {
 	struct net_device *netdev = pci_get_drvdata(pdev);
@@ -4482,9 +4464,6 @@ static const struct net_device_ops ixgbevf_netdev_ops = {
 	.ndo_tx_timeout		= ixgbevf_tx_timeout,
 	.ndo_vlan_rx_add_vid	= ixgbevf_vlan_rx_add_vid,
 	.ndo_vlan_rx_kill_vid	= ixgbevf_vlan_rx_kill_vid,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller	= ixgbevf_netpoll,
-#endif
 	.ndo_features_check	= ixgbevf_features_check,
 	.ndo_bpf		= ixgbevf_xdp,
 };
-- 
2.19.0.444.g18242da7ef-goog