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From: Hailiang Zhang <zhang.zhanghailiang@huawei.com>
Message-ID: <5810B822.9030202@huawei.com>
Date: Wed, 26 Oct 2016 22:05:22 +0800
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Subject: Re: [Qemu-devel] [PATCH COLO-Frame (Base) v21 05/17] COLO:
 Establish a new communicating path for COLO
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To: Amit Shah <amit.shah@redhat.com>
Cc: quintela@redhat.com, qemu-devel@nongnu.org, dgilbert@redhat.com, wency@cn.fujitsu.com, lizhijian@cn.fujitsu.com, xiecl.fnst@cn.fujitsu.com

On 2016/10/26 13:06, Amit Shah wrote:
> On (Tue) 18 Oct 2016 [20:10:01], zhanghailiang wrote:
>> This new communication path will be used for returning messages
>> from Secondary side to Primary side.
>>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>> Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
>> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>
> Reviewed-by: Amit Shah <amit.shah@redhat.com>
>
>> @@ -63,8 +75,24 @@ void *colo_process_incoming_thread(void *opaque)
>>       migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
>>                         MIGRATION_STATUS_COLO);
>>
>> +    mis->to_src_file = qemu_file_get_return_path(mis->from_src_file);
>> +    if (!mis->to_src_file) {
>> +        error_report("COLO incoming thread: Open QEMUFile to_src_file failed");
>> +        goto out;
>> +    }
>> +    /*
>> +     * Note: We set the fd to unblocked in migration incoming coroutine,
>> +     * But here we are in the COLO incoming thread, so it is ok to set the
>> +     * fd back to blocked.
>> +     */
>> +    qemu_file_set_blocking(mis->from_src_file, true);
>
> Why does it need to be blocking?
>

Because, the communication/action between Primary side and Secondary side should be
sequential. Just as postcopy does. :)

Thanks,
hailiang

> 		Amit
>
> .
>