From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:43490)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <quintela@redhat.com>) id 1c1t3C-00066y-A1
	for qemu-devel@nongnu.org; Wed, 02 Nov 2016 06:45:47 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <quintela@redhat.com>) id 1c1t38-0001KE-Cm
	for qemu-devel@nongnu.org; Wed, 02 Nov 2016 06:45:46 -0400
From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <1477943636-21024-3-git-send-email-duanj@linux.vnet.ibm.com>
	(Jianjun Duan's message of "Mon, 31 Oct 2016 12:53:55 -0700")
References: <1477943636-21024-1-git-send-email-duanj@linux.vnet.ibm.com>
	<1477943636-21024-3-git-send-email-duanj@linux.vnet.ibm.com>
Reply-To: quintela@redhat.com
Date: Wed, 02 Nov 2016 11:45:39 +0100
Message-ID: <87k2cm88j0.fsf@emacs.mitica>
MIME-Version: 1.0
Content-Type: text/plain
Subject: Re: [Qemu-devel] [QEMU PATCH v10 2/3] migration: migrate QTAILQ
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: Jianjun Duan <duanj@linux.vnet.ibm.com>
Cc: qemu-devel@nongnu.org, qemu-ppc@nongnu.org, dmitry@daynix.com, peter.maydell@linaro.org, kraxel@redhat.com, mst@redhat.com, david@gibson.dropbear.id.au, pbonzini@redhat.com, veroniabahaa@gmail.com, amit.shah@redhat.com, mreitz@redhat.com, kwolf@redhat.com, rth@twiddle.net, aurelien@aurel32.net, leon.alrae@imgtec.com, blauwirbel@gmail.com, mark.cave-ayland@ilande.co.uk, mdroth@linux.vnet.ibm.com, dgilbert@redhat.com

Jianjun Duan <duanj@linux.vnet.ibm.com> wrote:
> Currently we cannot directly transfer a QTAILQ instance because of the
> limitation in the migration code. Here we introduce an approach to
> transfer such structures. We created VMStateInfo vmstate_info_qtailq
> for QTAILQ. Similar VMStateInfo can be created for other data structures
> such as list.
>
> This approach will be used to transfer pending_events and ccs_list in spapr
> state.
>
> We also create some macros in qemu/queue.h to access a QTAILQ using pointer
> arithmetic. This ensures that we do not depend on the implementation
> details about QTAILQ in the migration code.
>
> Signed-off-by: Jianjun Duan <duanj@linux.vnet.ibm.com>


> +
> +    trace_get_qtailq(vmsd->name, version_id);
> +    if (version_id > vmsd->version_id) {
> +        error_report("%s %s",  vmsd->name, "too new");
> +        trace_get_qtailq_end(vmsd->name, "too new", -EINVAL);
> +
> +        return -EINVAL;
> +    }
> +    if (version_id < vmsd->minimum_version_id) {
> +        error_report("%s %s",  vmsd->name, "too old");
> +        trace_get_qtailq_end(vmsd->name, "too old", -EINVAL);
> +        return -EINVAL;
> +    }
> +
> +    while (qemu_get_byte(f)) {
> +        elm = g_malloc(size);

I think this is not generic enough.  We really need to allocate a new
element, and then fill it with default values.

virtio list code use it in this way.


Thanks, Juan.