From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:34868)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <zhang.zhanghailiang@huawei.com>) id 1c1OCB-0007Wn-6N
	for qemu-devel@nongnu.org; Mon, 31 Oct 2016 21:49:00 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <zhang.zhanghailiang@huawei.com>) id 1c1OC8-0001DZ-4M
	for qemu-devel@nongnu.org; Mon, 31 Oct 2016 21:48:59 -0400
Received: from szxga01-in.huawei.com ([58.251.152.64]:43733)
	by eggs.gnu.org with esmtps (TLS1.0:RSA_ARCFOUR_SHA1:16) (Exim 4.71)
	(envelope-from <zhang.zhanghailiang@huawei.com>) id 1c1OC7-00019L-Gl
	for qemu-devel@nongnu.org; Mon, 31 Oct 2016 21:48:56 -0400
References: <1477824430-1460-1-git-send-email-amit.shah@redhat.com>
	<1477824430-1460-7-git-send-email-amit.shah@redhat.com>
	<20161031182507.GB25480@thinpad.lan.raisama.net>
From: Hailiang Zhang <zhang.zhanghailiang@huawei.com>
Message-ID: <5817F459.2060702@huawei.com>
Date: Tue, 1 Nov 2016 09:48:09 +0800
MIME-Version: 1.0
In-Reply-To: <20161031182507.GB25480@thinpad.lan.raisama.net>
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Transfer-Encoding: 8bit
Subject: Re: [Qemu-devel] [PULL 06/18] COLO: Introduce checkpointing protocol
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Eduardo Habkost <ehabkost@redhat.com>, Amit Shah <amit.shah@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, qemu list <qemu-devel@nongnu.org>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, Juan Quintela <quintela@redhat.com>

On 2016/11/1 2:25, Eduardo Habkost wrote:
> On Sun, Oct 30, 2016 at 04:16:58PM +0530, Amit Shah wrote:
> [...]
>> +static void colo_wait_handle_message(QEMUFile *f, int *checkpoint_request,
>> +                                     Error **errp)
>> +{
>> +    COLOMessage msg;
>> +    Error *local_err = NULL;
>> +
>> +    msg = colo_receive_message(f, &local_err);
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>> +        return;
>> +    }
>> +
>> +    switch (msg) {
>> +    case COLO_MESSAGE_CHECKPOINT_REQUEST:
>> +        *checkpoint_request = 1;
>> +        break;
>> +    default:
>> +        *checkpoint_request = 0;
>> +        error_setg(errp, "Got unknown COLO message: %d", msg);
>> +        break;
>> +    }
>> +}
> [...]
>> +        colo_wait_handle_message(mis->from_src_file, &request, &local_err);
>> +        if (local_err) {
>> +            goto out;
>> +        }
>> +        assert(request);
>
> GCC 4.8.5 doesn't seem to be smart enough to notice that request
> will be always initialized:
>
>    /root/qemu/migration/colo.c: In function ‘colo_process_incoming_thread’:
>    /root/qemu/migration/colo.c:448:33: error: ‘request’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>             assert(request);
>                                     ^
>    cc1: all warnings being treated as errors
>
>    $ gcc --version
>    gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-4)
>

Yes, you are right, Jeff has sent a patch to fix this
'[PATCH 1/1] migration: fix compiler warning on uninitialized variable'

Thanks,
Hailiang