>> I'm surprised: did you test this with upstream qemu? That codebase
>> doesn't yet throttle writes, and this code path won't execute. Does
>> it really not reproduce with this patch?
>
> I think
> static void handle_output(VirtIODevice *vdev, VirtQueue *vq)
> [....]
> if (!port->throttled) {
> do_flush_queued_data(port, vq, vdev);
> return;
>
> makes a difference here, since we will never return the buffer to the guest,
> no?
And of course this while
static void do_flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq,
VirtIODevice *vdev)
[...]
while (!port->throttled) {
unsigned int i;
will also prevent further processing, as virtio_serial_throttle_port will
set port-throttled.
