Re: [PATCH v1 2/2] virtio-net: virtio_net_flush_tx() check for per-queue reset

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Jan 29, 2023 at 10:51:50AM +0800, Xuan Zhuo wrote:
> Check whether it is per-queue reset state in virtio_net_flush_tx().
> 
> Before per-queue reset, we need to recover async tx resources. At this
> time, virtio_net_flush_tx() is called, but we should not try to send
> new packets, so virtio_net_flush_tx() should check the current
> per-queue reset state.


What does "at this time" mean here?
Do you in fact mean it's called from flush_or_purge_queued_packets?
What does the call stack look like?

If yes introducing a vq state just so virtio_net_flush_tx
knows we are in the process of reset would be a bad idea.
We want something much more local, ideally on stack even ...


> 
> Fixes: 7dc6be52 ("virtio-net: support queue reset")
> Fixes: https://gitlab.com/qemu-project/qemu/-/issues/1451
> Reported-by: Alexander Bulekov <alxndr@bu.edu>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
>  hw/net/virtio-net.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 3ae909041a..fba6451a50 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -2627,7 +2627,8 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
>      VirtQueueElement *elem;
>      int32_t num_packets = 0;
>      int queue_index = vq2q(virtio_get_queue_index(q->tx_vq));
> -    if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> +    if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) ||
> +        virtio_queue_reset_state(q->tx_vq)) {
>          return num_packets;
>      }
>  
> -- 
> 2.32.0.3.g01195cf9f