Re: xl dev-detach hangs with missing frontends

[Wei Liu <wei.liu2@citrix.com>]

On Fri, Feb 12, 2016 at 03:53:06PM +0100, Olaf Hering wrote:
> On Fri, Feb 12, Wei Liu wrote:
> 
> > CC'ing other tools maintainer.
> > 
> > On Thu, Feb 11, 2016 at 11:37:49AM +0100, Olaf Hering wrote:
> > > How should libxl__initiate_device_generic_remove deal with devices which
> > 
> > I think you meant libxl__initiate_device_remove. There is no function
> > called libxl__initiate_device_generic _remove.
> 
> Not yet.
> 

I see. That function is renamed in PVUSB series.

> > > have no frontend driver? Right now it moves "state" from either
> > > XenbusStateInitialising or XenbusStateInitWait to XenbusStateClosing.
> > > Then it expects the backend to move "state" to XenbusStateClosed. This
> > > will never happen, at least for netback and scsiback. The result is a 10
> > > second delay.
> > > 
> > 
> > I don't think there is a way to tell whether there is no frontend driver
> > or the frontend driver is just too slow.
> 
> To handle this the code should check the current value of "state". If
> its XenbusStateInitialising or XenbusStateInitWait nothing should be
> done.

Right. The state is reliable for telling whether frontend is connected
or not.

Wei.

> 
> Olaf