virtio_net: 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.

virto_net 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: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7659209..dab504e 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1699,17 +1699,6 @@ static void virtnet_stats(struct net_device *dev,
        tot->rx_frame_errors = dev->stats.rx_frame_errors;
 }
 
-#ifdef CONFIG_NET_POLL_CONTROLLER
-static void virtnet_netpoll(struct net_device *dev)
-{
-       struct virtnet_info *vi = netdev_priv(dev);
-       int i;
-
-       for (i = 0; i < vi->curr_queue_pairs; i++)
-               napi_schedule(&vi->rq[i].napi);
-}
-#endif
-
 static void virtnet_ack_link_announce(struct virtnet_info *vi)
 {
        rtnl_lock();
@@ -2447,9 +2436,6 @@ static const struct net_device_ops virtnet_netdev = {
        .ndo_get_stats64     = virtnet_stats,
        .ndo_vlan_rx_add_vid = virtnet_vlan_rx_add_vid,
        .ndo_vlan_rx_kill_vid = virtnet_vlan_rx_kill_vid,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-       .ndo_poll_controller = virtnet_netpoll,
-#endif
        .ndo_bpf                = virtnet_xdp,
        .ndo_xdp_xmit           = virtnet_xdp_xmit,
        .ndo_features_check     = passthru_features_check,