Re: [PATCH 09/10] vfio: ccw: Suppressing the BOXED state

[Cornelia Huck]

On Wed, 25 Apr 2018 15:55:51 +0200
Pierre Morel <pmorel@xxxxxxxxxxxxxxxxxx> wrote:

> On 25/04/2018 10:44, Cornelia Huck wrote:
> > On Thu, 19 Apr 2018 16:48:12 +0200
> > Pierre Morel <pmorel@xxxxxxxxxxxxxxxxxx> wrote:
> >  
> >> VFIO_CCW_STATE_BOXED and VFIO_CCW_STATE_BUSY are the same
> >> states.
> >> Let's only keep one: VFIO_CCW_STATE_BUSY
> >>
> >> Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxxxxxxx>
> >> ---
> >>   drivers/s390/cio/vfio_ccw_fsm.c     | 9 ---------
> >>   drivers/s390/cio/vfio_ccw_private.h | 1 -
> >>   2 files changed, 10 deletions(-)  
> > I think they were initially supposed to cover two different things:
> > - BUSY: we're currently dealing with an I/O request
> > - BOXED: the device currently won't talk to us or we won't talk to it
> >
> > It seems we never really did anything useful with BOXED; but should we?
> >  
> I do not know what.

The BUSY state is something we know that we'll get out of soon-ish
(when the I/O request has finished). We could conceivably use a timeout
and drop to the BOXED state if we don't get an answer.

I think this plays also into the reserve/release and path handling
questions. One of the more common reasons for devices to become boxed
I've seen is another system doing a reserve on a dasd.