On Wed, Oct 17, 2018 at 07:44:12PM +0900, Ake Koomsin wrote:
> 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@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Thanks a lot for debugging!
Seems like stable material to me, right?
> ---
> 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;
> }
>
> --
> 2.19.1
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