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From: Jason Wang <jasowang@redhat.com>
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Date: Thu, 10 Mar 2016 10:28:15 +0800
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Subject: Re: [Qemu-devel] [PULL 00/14] Net patches
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To: Peter Maydell <peter.maydell@linaro.org>, Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Cc: QEMU Developers <qemu-devel@nongnu.org>



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.
>
> thanks
> -- PMM
>

+1

To make sure the connected socket to be proceeded before iov_send(), you
could use some like  qmp("{ 'execute' : 'query-status'}") before
iov_send(). With this we are guaranteed that connected is setting to
true before iov_send().