Re: [Qemu-devel] [PATCH 1/2] rtl8139: Do not consume the packet during overflow in standard mode.

[Vlad Yasevich <vyasevic@redhat.com>]

On 08/26/2015 08:18 AM, Stefan Hajnoczi wrote:
> 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.

Isn't that already there.  A few drivers already return 0 to trigger a requeue.  What's
missing?


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

It calls it on read, once it's consumed a packet, to advance to the next packet in the
buffer.

-vlad