On Thu, Jan 2, 2020 at 1:50 AM Michael S. Tsirkin <m...@redhat.com> wrote:

> On Thu, Dec 26, 2019 at 11:29:50AM +0200, Yuri Benditovich wrote:
> > On Thu, Dec 26, 2019 at 10:58 AM Jason Wang <jasow...@redhat.com> wrote:
> > >
> > >
> > > On 2019/12/26 下午12:36, Yuri Benditovich wrote:
> > > > https://bugzilla.redhat.com/show_bug.cgi?id=1708480
> > > > Fix leak of region reference that prevents complete
> > > > device deletion on hot unplug.
> > >
> > >
> > > More information is needed here, the bug said only q35 can meet this
> > > issue. What makes q35 different here?
> > >
> >
> > I do not have any ready answer, I did not dig into it too much.
> > Probably Michael Tsirkin or Paolo Bonzini can answer without digging.
>
>
>
> > >
> > > >
> > > > Signed-off-by: Yuri Benditovich <yuri.benditov...@daynix.com>
> > > > ---
> > > >   hw/virtio/virtio.c | 5 +++++
> > > >   1 file changed, 5 insertions(+)
> > > >
> > > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> > > > index 04716b5f6c..baadec8abc 100644
> > > > --- a/hw/virtio/virtio.c
> > > > +++ b/hw/virtio/virtio.c
> > > > @@ -2340,6 +2340,11 @@ void virtio_del_queue(VirtIODevice *vdev, int
> n)
> > > >       vdev->vq[n].vring.num_default = 0;
> > > >       vdev->vq[n].handle_output = NULL;
> > > >       vdev->vq[n].handle_aio_output = NULL;
> > > > +    /*
> > > > +     * with vring.num = 0 the queue will be ignored
> > > > +     * in later loops of region cache reset
> > > > +     */
> > >
> > >
> > > I can't get the meaning of this comment.
> > >
> > > Thanks
> > >
> > >
> > > > +    virtio_virtqueue_reset_region_cache(&vdev->vq[n]);
>
>
> Do we need to drop this from virtio_device_free_virtqueues then?
>
>
Not mandatory. Repetitive  virtio_virtqueue_reset_region_cache does not do
anything bad.
Some of virtio devices do not do 'virtio_del_queue' at all. Currently
virtio_device_free_virtqueues resets region cache for them.
IMO, not calling 'virtio_del_queue' is a bug, but not in the scope of
current series, I'll take care of that later.


> > > >       g_free(vdev->vq[n].used_elems);
> > > >   }
> > > >
> > >
>
>

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