On 07/15/2015 11:02 AM, Fam Zheng wrote:
> This patch fixes network hang after "stop" then "cont", while network
> packets keep arriving.
>
> Tested both manually (tap, host pinging guest) and with Jason's qtest
> series (plus his "[PATCH 2.4] socket: pass correct size in
> net_socket_send()" fix).
>
> As virtio_net_set_status is called when guest driver is setting status
> byte and when vm state is changing, it is a good opportunity to flush
> queued packets.
>
> This is necessary because during vm stop the backend (e.g. tap) would
> stop rx processing after .can_receive returns false, until the queue is
> explicitly flushed or purged.
>
> The other interesting condition in .can_receive, virtio_queue_ready(),
> is handled by virtio_net_handle_rx() when guest kicks; the 3rd condition
> is invalid queue index which doesn't need flushing.
>
> Signed-off-by: Fam Zheng <f...@redhat.com>
>
> ---
Reviewed-by: Jason Wang <jasow...@redhat.com>
btw, there's another condition in can_receive() which is suspicious:
...
if (nc->queue_index >= n->curr_queues) {
return 0;
}
...
This requires queue to be flushed when the number of queues was
increased. But it looks unnecessary since both guest and vhost does not
care about this. So I think we could safely just remove this condition.
Maybe a patch on top.
Thanks
>
> v2: Limit to "virtio_net_started(n, queue_status) &&
> !n->vhost_started".[MST]
> ---
> hw/net/virtio-net.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index d728233..24c7be1 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -162,6 +162,8 @@ static void virtio_net_set_status(struct VirtIODevice
> *vdev, uint8_t status)
> virtio_net_vhost_status(n, status);
>
> for (i = 0; i < n->max_queues; i++) {
> + NetClientState *ncs = qemu_get_subqueue(n->nic, i);
> + bool queue_started;
> q = &n->vqs[i];
>
> if ((!n->multiqueue && i != 0) || i >= n->curr_queues) {
> @@ -169,12 +171,18 @@ static void virtio_net_set_status(struct VirtIODevice
> *vdev, uint8_t status)
> } else {
> queue_status = status;
> }
> + queue_started =
> + virtio_net_started(n, queue_status) && !n->vhost_started;
> +
> + if (queue_started) {
> + qemu_flush_queued_packets(ncs);
> + }
>
> if (!q->tx_waiting) {
> continue;
> }
>
> - if (virtio_net_started(n, queue_status) && !n->vhost_started) {
> + if (queue_started) {
> if (q->tx_timer) {
> timer_mod(q->tx_timer,
> qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
> n->tx_timeout);
