Re: [PATCH v3 2/2] net: tulip: add .can_recieve routine

[Jason Wang]

On 2020/3/17 上午2:01, P J P wrote:
>    Hello Stefan, Jason,
>
> +-- On Fri, 6 Mar 2020, Stefan Hajnoczi wrote --+
> | > +static int
> | > +tulip_can_receive(NetClientState *nc)
> | > +{
> | > +    TULIPState *s = qemu_get_nic_opaque(nc);
> | > +
> | > +    if (s->rx_frame_len || tulip_rx_stopped(s)) {
> | > +        return false;
> | > +    }
> | > +
> | > +    return true;
> | > +}
> |
> | Are the required qemu_flush_queued_packets() calls in place so that
> | packet transfer wakes up again when .can_receive() transitions from
> | false to true?
>
>    Yes, qemu_flush_queued_packets() calls are in tulip_write(). Do we need to
> call tulip_can_receive() before each call?


Probably not, just need to make sure the check in tulip_rx_stopped(s) 
matches the action that triggers qemu_flush_queued_packets() in 
tulip_write() is sufficient.

This to make sure net core can restore the receiving.

Btw, what's the point of checking rx_frame_len here?

Thanks


> Thank you.
> --
> Prasad J Pandit / Red Hat Product Security Team
> 8685 545E B54C 486B C6EB 271E E285 8B5A F050 DE8D