On Tue, Sep 06, 2016 at 04:45:13AM +0300, Michael S. Tsirkin wrote:
> On Mon, Sep 05, 2016 at 11:02:36AM +0300, Roman Kagan wrote:
> > On Sat, Sep 03, 2016 at 01:53:53AM +0300, Michael S. Tsirkin wrote:
> > > On Fri, Sep 02, 2016 at 10:21:58AM +0300, Roman Kagan wrote:
> > > > On Thu, Sep 01, 2016 at 10:26:54PM +0300, Michael S. Tsirkin wrote:
> > > > > I'm sorry - I don't like this patch. This means that
> > > > > virtio_balloon_receive_stats will be called and will poke
> > > > > at the ring even if the ring was never kicked.
> > > >
> > > > I'm not sure I understand what the problem is with that:
> > > > virtio_balloon_receive_stats just returns early if virtio_queue_empty(),
> > > > which is no more poking at the ring than is already done in virtio_load.
> > >
> > > Generally we should not look at ring until there was a kick.
> >
> > How else would you recover ->inuse?
> >
> > Roman.
>
> We seem to do this:
> + vdev->vq[i].inuse = vdev->vq[i].last_avail_idx -
> + vdev->vq[i].used_idx;
Right, but .used_idx is fetched from vring two lines above:
vdev->vq[i].used_idx = vring_used_idx(&vdev->vq[i]);
> Is this wrong?
And no, I don't think it is wrong :) I guess there's just no other way
to obtain it.
Roman.
