From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:57164)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1Zr9BT-00040C-N3
	for qemu-devel@nongnu.org; Tue, 27 Oct 2015 14:41:24 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1Zr9BS-0005fq-RQ
	for qemu-devel@nongnu.org; Tue, 27 Oct 2015 14:41:23 -0400
Sender: Paolo Bonzini <paolo.bonzini@gmail.com>
References: <1445954986-13005-1-git-send-email-den@openvz.org>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <562FC546.9040709@redhat.com>
Date: Tue, 27 Oct 2015 19:41:10 +0100
MIME-Version: 1.0
In-Reply-To: <1445954986-13005-1-git-send-email-den@openvz.org>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH v2 0/5] dataplane snapshot fixes
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: "Denis V. Lunev" <den@openvz.org>
Cc: qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, qemu-stable@nongnu.org

On 27/10/2015 15:09, Denis V. Lunev wrote:
> The following test
>     while /bin/true ; do
>         virsh snapshot-create rhel7
>         sleep 10
>         virsh snapshot-delete rhel7 --current
>     done
> with enabled iothreads on a running VM leads to a lot of troubles: hangs,
> asserts, errors.
> 
> Though (in general) HMP snapshot code is terrible. I think it should be
> dropped at once and replaced with blkdev transactions code. Though is
> could not fit to QEMU 2.5/stable at all.
> 
> Anyway, I think that the construction like
>     assert(aio_context_is_locked(aio_context));
> should be widely used to ensure proper locking.
> 
> Changes from v1:
> - aio-context locking added
> - comment is rewritten
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Paolo Bonzini <pbonzini@redhat.com>

For patches 4-5:

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

For patches 1-3 I'm not sure, because we will remove RFifoLock
relatively soon and regular pthread recursive mutexes do not have an
equivalent of rfifolock_is_locked.

Paolo