virtio_net: enable napi for all possible queues during open

Commit 55257d72bd1c51f25106350f4983ec19f62ed1fa (virtio-net: fill only rx
queues which are being used) only does the napi enabling during open for
curr_queue_pairs. This will break multiqueue receiving since napi of new queues
were still disabled after changing the number of queues.

This patch fixes this by enabling napi for all possible queues during open.

Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/virtio_net.c

@@ -636,10 +636,11 @@ static int virtnet_open(struct net_device *dev)
 	struct virtnet_info *vi = netdev_priv(dev);
 	int i;
 
-	for (i = 0; i < vi->curr_queue_pairs; i++) {
-		/* Make sure we have some buffers: if oom use wq. */
-		if (!try_fill_recv(&vi->rq[i], GFP_KERNEL))
-			schedule_delayed_work(&vi->refill, 0);
+	for (i = 0; i < vi->max_queue_pairs; i++) {
+		if (i < vi->curr_queue_pairs)
+			/* Make sure we have some buffers: if oom use wq. */
+			if (!try_fill_recv(&vi->rq[i], GFP_KERNEL))
+				schedule_delayed_work(&vi->refill, 0);
 		virtnet_napi_enable(&vi->rq[i]);
 	}