Commit 713a98d90c5e ("virtio-net: serialize tx routine during reset")
introduces netif_tx_disable() after netif_device_detach() in order to
avoid use-after-free of tx queues. However, there are two issues.

1) Its operation is redundant with netif_device_detach() in case the
    interface is running.
2) In case of the interface is not running before suspending and
    resuming, the tx does not get resumed by netif_device_attach().
    This results in losing network connectivity.

It is better to use netif_tx_lock_bh()/netif_tx_unlock_bh() instead for
serializing tx routine during reset. This also preserves the symmetry
of netif_device_detach() and netif_device_attach().

Fixes commit 713a98d90c5e ("virtio-net: serialize tx routine during reset")
Signed-off-by: Ake Koomsin <redacted>
---
  drivers/net/virtio_net.c | 5 ++++-
  1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 3f5aa59c37b7..3e2c041d76ac 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -2267,8 +2267,9 @@ static void virtnet_freeze_down(struct virtio_device *vdev)
  	/* Make sure no work handler is accessing the device */
  	flush_work(&vi->config_work);
  
+	netif_tx_lock_bh(vi->dev);
  	netif_device_detach(vi->dev);
-	netif_tx_disable(vi->dev);
+	netif_tx_unlock_bh(vi->dev);
  	cancel_delayed_work_sync(&vi->refill);
  
  	if (netif_running(vi->dev)) {

@@ -2304,7 +2305,9 @@ static int virtnet_restore_up(struct virtio_device *vdev)
  		}
  	}
  
+	netif_tx_lock_bh(vi->dev);
  	netif_device_attach(vi->dev);
+	netif_tx_unlock_bh(vi->dev);
  	return err;
  }