P J P <ppandit@redhat.com> 于2020年3月23日周一 下午8:25写道：

> From: Prasad J Pandit <pjp@fedoraproject.org>
>
> Define .can_receive routine to do sanity checks before receiving
> packet data. And call qemu_flush_queued_packets to flush queued
> packets once they are read in tulip_receive().
>
> Suggested-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> ---
>  hw/net/tulip.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
>
> Update v6: merge earlier patch 2 & 3 into one
>   -> https://lists.gnu.org/archive/html/qemu-devel/2020-03/msg06868.html
>
> diff --git a/hw/net/tulip.c b/hw/net/tulip.c
> index fbe40095da..8d8c9519e7 100644
> --- a/hw/net/tulip.c
> +++ b/hw/net/tulip.c
> @@ -229,6 +229,18 @@ static bool tulip_filter_address(TULIPState *s, const
> uint8_t *addr)
>      return ret;
>  }
>
> +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;
> +}
> +
>  static ssize_t tulip_receive(TULIPState *s, const uint8_t *buf, size_t
> size)
>  {
>      struct tulip_descriptor desc;
> @@ -236,7 +248,7 @@ static ssize_t tulip_receive(TULIPState *s, const
> uint8_t *buf, size_t size)
>      trace_tulip_receive(buf, size);
>
>      if (size < 14 || size > sizeof(s->rx_frame) - 4
> -        || s->rx_frame_len || tulip_rx_stopped(s)) {
> +        || !tulip_can_receive(s->nic->ncs)) {
>          return 0;
>      }
>
> @@ -275,6 +287,8 @@ static ssize_t tulip_receive(TULIPState *s, const
> uint8_t *buf, size_t size)
>          tulip_desc_write(s, s->current_rx_desc, &desc);
>          tulip_next_rx_descriptor(s, &desc);
>      } while (s->rx_frame_len);
> +
> +    qemu_flush_queued_packets(qemu_get_queue(s->nic));
>


Hi Prasad ans Jason,
I want to know why here we need call 'qemu_flush_queued_packets'.
AFAICS, the other networking card emulation need no this.

Thanks,
Li Qiang



>      return size;
>  }
>
> @@ -288,6 +302,7 @@ static NetClientInfo net_tulip_info = {
>      .type = NET_CLIENT_DRIVER_NIC,
>      .size = sizeof(NICState),
>      .receive = tulip_receive_nc,
> +    .can_receive = tulip_can_receive,
>  };
>
>  static const char *tulip_reg_name(const hwaddr addr)
> --
> 2.25.1
>
>
>