Re: [Qemu-devel] [PATCH V3] net: Fix dealing with packets when runstate changes

[zhanghailiang <zhang.zhanghailiang@huawei.com>]

On 2014/8/26 12:39, Jason Wang wrote:
> On 08/25/2014 06:47 PM, zhanghailiang wrote:
>> For all NICs(except virtio-net) emulated by qemu,
>> Such as e1000, rtl8139, pcnet and ne2k_pci,
>> Qemu can still receive packets when VM is not running.
>> If this happened in *migration's* last PAUSE VM stage,
>> The new dirty RAM related to the packets will be missed,
>> And this will lead serious network fault in VM.
>>
>> To avoid this, we forbid receiving packets in generic net code when
>> VM is not running. Also, when the runstate changes back to running,
>> we definitely need to flush queues to get packets flowing again.
>>
>> Here we implement this in the net layer:
>> (1) Judge the vm runstate in qemu_can_send_packet
>> (2) Add a member 'VMChangeStateEntry *vmstate' to struct NICState,
>> Which will listen for VM runstate changes.
>> (3) Register a handler function for VMstate change.
>> When vm changes back to running, we flush all queues in the callback function.
>> (4) Remove checking vm state in virtio_net_can_receive
>>
>> Signed-off-by: zhanghailiang<zhang.zhanghailiang@huawei.com>
>> ---
>>   v3:
>> - change the 'vmstate' to 'vm_running'
>>
>>   v2:
>> - remove the superfluous check of nc->received_disabled
>> ---
>> hw/net/virtio-net.c |  4 ----
>>   include/net/net.h   |  2 ++
>>   net/net.c           | 31 +++++++++++++++++++++++++++++++
>>   3 files changed, 33 insertions(+), 4 deletions(-)
> Hi:
>
> Have you seen Stefan's replied? We think there's no need to flush the
> queued packets or is there anything new issue you found?
>

Hi Jason,

Sorry, maybe i have missed it but i have searched that in internet,
And got what happened.;)

Hmm, you are right! i will send another patch which removing the unnecessary
flush action and also a more clear commit log.


Thanks,
zhanghailiang