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From: Jason Wang <jasowang@redhat.com>
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Date: Tue, 15 Mar 2016 11:15:01 +0800
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Subject: Re: [Qemu-devel] [PULL 00/14] Net patches
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To: Li Zhijian <lizhijian@cn.fujitsu.com>, Wen Congyang <wency@cn.fujitsu.com>, Peter Maydell <peter.maydell@linaro.org>, Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Cc: QEMU Developers <qemu-devel@nongnu.org>



On 03/09/2016 12:26 PM, Li Zhijian wrote:
>
>
> On 03/09/2016 09:36 AM, Wen Congyang wrote:
>> On 03/08/2016 05:54 PM, Peter Maydell wrote:
>>> On 8 March 2016 at 16:06, Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
>>> wrote:
>>>> I found the reason for this problem is that
>>>> unix_connect() have not connect to sock_path before iov_send().
>>>> It need time to establish connection. so can we fix it with usleep()
>>>> like this:
>>>>
>>>>      recv_sock = unix_connect(sock_path, NULL);
>>>>      g_assert_cmpint(recv_sock, !=, -1);
>>>> +    usleep(1000);
>>>>
>>>>      ret = iov_send(send_sock[0], iov, 2, 0, sizeof(size) +
>>>> sizeof(send_buf));
>>>>      g_assert_cmpint(ret, ==, sizeof(send_buf) + sizeof(size));
>>>>      close(send_sock[0]);
>>>>
>>>>      ret = qemu_recv(recv_sock, &len, sizeof(len), 0);
>>>
>>> I would prefer it if we could find a way to fix this race
>>> reliably rather than just inserting a delay and hoping it
>>> is sufficient. Otherwise the test is likely to be unreliable
>>> if run on a heavily loaded or slow machine.
>>
>> Yes, but there is no way to know when tcp_chr_accept() is called. Add
>> a event
>> to notify it?
>>
>> Thanks
>> Wen Congyang
>>
>
> Hi, Jason, PMM
> As Congyang said that this is a bug of testcase instead of filter-mirror.
> Maybe we should re-wrok the testcase, for example
> - using -chardev pipe instead of -chardev socket, because we are
>   intend to test the packet mirror fuction instead of -chardev socket
>
> How about that ?

I still prefer to use socket since it will be more similar to its real
usage (e.g COLO).

Btw, I haven't investigated deeply, but at least qmp command trick
should work. But what's better is to passing the pre-connected fd (e.g
the socket created by socketpair()) to chardev, not sure we can do this.