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Re: [Qemu-devel] [PATCH 2/3] virtio-9p: add unrealize handler
From: |
Greg Kurz |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] virtio-9p: add unrealize handler |
Date: |
Fri, 9 Oct 2015 12:54:09 +0200 |
On Fri, 9 Oct 2015 10:36:56 +0300
"Michael S. Tsirkin" <address@hidden> wrote:
> On Fri, Oct 09, 2015 at 09:23:49AM +0200, Greg Kurz wrote:
> > On Wed, 07 Oct 2015 14:20:28 +0530
> > "Aneesh Kumar K.V" <address@hidden> wrote:
> >
> > > Stefan Hajnoczi <address@hidden> writes:
> > >
> > > > 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 <address@hidden>
> > > >> ---
> > > >> 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 enable migration blocker when we have an active mount. So if we get
> > > here, that should indicate no active 9p mounts.
> > >
> > > -aneesh
> >
> > Oops.. Stefan is talking about hot-unplug versus in-flight requests... not
> > about migration. And there is no such thing as a hot-unplug blocker...
>
> If unplug request fails, that should be enough.
>
Like setting @hotpluggable to false for the virtio-9p-pci class ? I see no
other way for the unplug request to fail... but I will happily accept all
suggestions :)
--
Greg