RE: [Xen-devel] [PATCH 2/4] xenbus: limit when state is forced to closed

[Durrant, Paul]

> -----Original Message-----
> From: JÃrgen Groà <jgross@xxxxxxxx>
> Sent: 09 December 2019 11:55
> To: Roger Pau Monnà <roger.pau@xxxxxxxxxx>; Durrant, Paul
> <pdurrant@xxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxxx; Stefano
> Stabellini <sstabellini@xxxxxxxxxx>; Boris Ostrovsky
> <boris.ostrovsky@xxxxxxxxxx>
> Subject: Re: [Xen-devel] [PATCH 2/4] xenbus: limit when state is forced to
> closed
> 
> On 09.12.19 12:39, Roger Pau Monnà wrote:
> > On Thu, Dec 05, 2019 at 02:01:21PM +0000, Paul Durrant wrote:
> >> Only force state to closed in the case when the toolstack may need to
> >> clean up. This can be detected by checking whether the state in
> xenstore
> >> has been set to closing prior to device removal.
> >
> > I'm not sure I see the point of this, I would expect that a failure to
> > probe or the removal of the device would leave the xenbus state as
> > closed, which is consistent with the actual driver state.
> >
> > Can you explain what's the benefit of leaving a device without a
> > driver in such unknown state?
> 
> And more concerning: did you check that no frontend/backend is
> relying on the closed state to be visible without closing having been
> set before?

Blkfront doesn't seem to mind and I believe the Windows PV drivers cope, but I don't really understand the comment since this patch is actually removing a case where the backend transitions directly to closed.

  Paul

> 
> 
> Juergen