Re: [Qemu-devel] [PATCH] do not send packet to nic if the packet will be dropped by nic

[Kevin Wolf]

Am 17.06.2011 03:33, schrieb Wen Congyang:
> If !s->clock_enabled or !rtl8139_receiver_enabled(s), it means that
> the nic will drop all packets from host. So qemu will keep getting
> packets from host and wasting CPU on dropping packets. This seems
> worse than packets that should be dropped but aren't.
> 
> Signed-off-by: Wen Congyang <address@hidden>

Which bug does this change fix? I'm still not convinced that we should
do it.

> ---
>  hw/rtl8139.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/rtl8139.c b/hw/rtl8139.c
> index 2f8db58..9084678 100644
> --- a/hw/rtl8139.c
> +++ b/hw/rtl8139.c
> @@ -810,9 +810,9 @@ static int rtl8139_can_receive(VLANClientState *nc)
>  
>      /* Receive (drop) packets if card is disabled.  */

This comment isn't accurate any more after applying the patch.

>      if (!s->clock_enabled)
> -      return 1;
> +      return 0;
>      if (!rtl8139_receiver_enabled(s))
> -      return 1;
> +      return 0;
>  
>      if (rtl8139_cp_receiver_enabled(s)) {
>          /* ??? Flow control not implemented in c+ mode.
> -- 1.7.1 

Kevin