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Date: Wed, 26 Aug 2015 13:18:23 +0100
From: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20150826121823.GE30715@stefanha-thinkpad.redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/2] rtl8139: Do not consume the packet
 during overflow in standard mode.
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To: Vladislav Yasevich <vyasevic@redhat.com>
Cc: jasowang@redhat.com, qemu-devel@nongnu.org

On Fri, Aug 21, 2015 at 02:59:24PM -0700, Vladislav Yasevich wrote:
> When operation in standard mode, we currently return the size
> of packet during buffer overflow.  This consumes the overflow
> packet.  Return 0 instead so we can re-process the overflow packet
> when we have room.
> 
> This fixes issues with lost/dropped fragments of large messages.
> 
> Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
> ---
>  hw/net/rtl8139.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c
> index edbb61c..359e001 100644
> --- a/hw/net/rtl8139.c
> +++ b/hw/net/rtl8139.c
> @@ -1157,7 +1157,7 @@ static ssize_t rtl8139_do_receive(NetClientState *nc, const uint8_t *buf, size_t
>              s->IntrStatus |= RxOverflow;
>              ++s->RxMissed;
>              rtl8139_update_irq(s);
> -            return size_;
> +            return 0;

Every .receive() return 0 must be paired with a
qemu_flush_queued_packets() call.

Is rtl8139_RxBufPtr_write() guaranteed to be called when the guest
refills rx buffers?