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

From: Pierre Morel
Date: Thu May 03 2018 - 05:02:50 EST


On 30/04/2018 17:47, Cornelia Huck wrote:
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.

Absolutely, timeout on requests is something I wanted to do in a second series.


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.


--
Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany