virtio_net: remove custom busy_poll

Generic NAPI busy polling allows us to remove custom implementations
found in drivers.

It is possible further optimization could be done by testing
napi_complete_done() return value.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/virtio_net.c

@@ -29,7 +29,6 @@
 #include <linux/slab.h>
 #include <linux/cpu.h>
 #include <linux/average.h>
-#include <net/busy_poll.h>
 
 static int napi_weight = NAPI_POLL_WEIGHT;
 module_param(napi_weight, int, 0444);
@@ -1024,43 +1023,6 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
 	return received;
 }
 
-#ifdef CONFIG_NET_RX_BUSY_POLL
-/* must be called with local_bh_disable()d */
-static int virtnet_busy_poll(struct napi_struct *napi)
-{
-	struct receive_queue *rq =
-		container_of(napi, struct receive_queue, napi);
-	struct virtnet_info *vi = rq->vq->vdev->priv;
-	int r, received = 0, budget = 4;
-
-	if (!(vi->status & VIRTIO_NET_S_LINK_UP))
-		return LL_FLUSH_FAILED;
-
-	if (!napi_schedule_prep(napi))
-		return LL_FLUSH_BUSY;
-
-	virtqueue_disable_cb(rq->vq);
-
-again:
-	received += virtnet_receive(rq, budget);
-
-	r = virtqueue_enable_cb_prepare(rq->vq);
-	clear_bit(NAPI_STATE_SCHED, &napi->state);
-	if (unlikely(virtqueue_poll(rq->vq, r)) &&
-	    napi_schedule_prep(napi)) {
-		virtqueue_disable_cb(rq->vq);
-		if (received < budget) {
-			budget -= received;
-			goto again;
-		} else {
-			__napi_schedule(napi);
-		}
-	}
-
-	return received;
-}
-#endif	/* CONFIG_NET_RX_BUSY_POLL */
-
 static int virtnet_open(struct net_device *dev)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
@@ -1816,9 +1778,6 @@ static const struct net_device_ops virtnet_netdev = {
 	.ndo_vlan_rx_kill_vid = virtnet_vlan_rx_kill_vid,
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	.ndo_poll_controller = virtnet_netpoll,
-#endif
-#ifdef CONFIG_NET_RX_BUSY_POLL
-	.ndo_busy_poll		= virtnet_busy_poll,
 #endif
 	.ndo_xdp		= virtnet_xdp,
 };