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Date: Tue, 6 Oct 2015 11:13:27 +0200
From: Greg Kurz <gkurz@linux.vnet.ibm.com>
Message-ID: <20151006111327.2bd7fedd@bahia.local>
In-Reply-To: <20151006080914.GB19089@stefanha-thinkpad>
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Subject: Re: [Qemu-devel] [PATCH 2/3] virtio-9p: add unrealize handler
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>, aneesh.kumar@linux.vnet.ibm.com, qemu-devel@nongnu.org

On Tue, 6 Oct 2015 09:09:14 +0100
Stefan Hajnoczi <stefanha@gmail.com> wrote:

> On Mon, Oct 05, 2015 at 11:07:23AM +0200, Greg Kurz wrote:
> > If the user tries to hot unplug a virtio-9p device, it seems to succeed but
> > in fact:
> > - virtio-9p coroutines thread pool and async queue are leaked
> > - QEMU crashes in virtio_vmstate_change() if the user tries to live migrate
> > 
> > This patch brings hot unplug support to virtio-9p-device. It fixes both
> > above issues.
> > 
> > Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
> > ---
> >  hw/9pfs/virtio-9p-device.c |   12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> 
> What happens to in-flight I/O requests?  We cannot assume that the guest
> driver quiesces the device.
> 

We can assume that the guest has unmounted the 9p share otherwise migration
is blocked... is it possible we still have in-flight I/O requests in this
scenario ?