commit 05c998b738fdd3e5d6a257bcacc8f34b6284d795
author Ake Koomsin <ake@igel.co.jp> Wed Oct 17 19:44:12 2018 +0900
committer David S. Miller <davem@davemloft.net> Wed Oct 17 22:29:30 2018 -0700
tree 07d022a2799373d700ce72650a95b51c7af70bf8
parent 84dad55951b0d009372ec21760b650634246e144

virtio_net: avoid using netif_tx_disable() for serializing tx routine

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 <ake@igel.co.jp>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>