Re: [PATCH] net: use peer when purging queue in qemu_flush_or_purge_queue_packets()

[Jason Wang <jasowang@redhat.com>]

On 2020/5/18 下午4:00, Philippe Mathieu-Daudé wrote:
> Hi Jason,
>
> On 5/18/20 5:34 AM, Jason Wang wrote:
>> On 2020/5/11 下午12:21, Alexander Bulekov wrote:
>>> On 200511 1204, Jason Wang wrote:
>>>> The sender of packet will be checked in the qemu_net_queue_purge() but
>>>> we use NetClientState not its peer when trying to purge the incoming
>>>> queue in qemu_flush_or_purge_packets(). This will trigger the assert
>>>> in virtio_net_reset since we can't pass the sender check.
>>>>
>>>> Fix by using the peer.
>
> Can you please include the backtrace:
>
> hw/net/virtio-net.c:533: void virtio_net_reset(VirtIODevice *): Assertion
> `!virtio_net_get_subqueue(nc)->async_tx.elem' failed.
> #9 0x55a33fa31b78 in virtio_net_reset hw/net/virtio-net.c:533:13
> #10 0x55a33fc88412 in virtio_reset hw/virtio/virtio.c:1919:9
> #11 0x55a341d82764 in virtio_bus_reset hw/virtio/virtio-bus.c:95:9
> #12 0x55a341dba2de in virtio_pci_reset hw/virtio/virtio-pci.c:1824:5
> #13 0x55a341db3e02 in virtio_pci_common_write 
> hw/virtio/virtio-pci.c:1252:13
> #14 0x55a33f62117b in memory_region_write_accessor memory.c:496:5
> #15 0x55a33f6205e4 in access_with_adjusted_size memory.c:557:18
> #16 0x55a33f61e177 in memory_region_dispatch_write memory.c:1488:16
>
> And link to reproducer:
> https://www.mail-archive.com/qemu-devel@nongnu.org/msg701914.html
>
> Thanks,


Done.

Thanks


>
> Phil.
>
> (Alexander, this is an example of why launchpad bug reports are easier 
> to refer in commit history).
>
>>>>
>>>> Reported-by: "Alexander Bulekov" <alxndr@bu.edu>
>>>> Fixes: ca77d85e1dbf9 ("net: complete all queued packets on VM stop")
>>>> Cc: qemu-stable@nongnu.org
>>>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>>> Hi Jason,
>>> With this patch, I can no longer reproduce the crash
>>>
>>> Acked-by: Alexander Bulekov <alxndr@bu.edu>
>>>
>>> Thanks!
>>
>>
>> Applied.
>>
>> Thanks
>>
>>
>>
>>>
>>>> ---
>>>>   net/net.c | 2 +-
>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/net/net.c b/net/net.c
>>>> index 38778e831d..9e47cf727d 100644
>>>> --- a/net/net.c
>>>> +++ b/net/net.c
>>>> @@ -610,7 +610,7 @@ void 
>>>> qemu_flush_or_purge_queued_packets(NetClientState *nc, bool purge)
>>>>           qemu_notify_event();
>>>>       } else if (purge) {
>>>>           /* Unable to empty the queue, purge remaining packets */
>>>> -        qemu_net_queue_purge(nc->incoming_queue, nc);
>>>> +        qemu_net_queue_purge(nc->incoming_queue, nc->peer);
>>>>       }
>>>>   }
>>>> -- 
>>>> 2.20.1
>>>>
>>
>>
>