From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cornelia Huck <cohuck@redhat.com>
Subject: Re: [PATCH v2 2/5] vfio-ccw: concurrent I/O handling
Date: Thu, 24 Jan 2019 11:19:34 +0100
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Cc: linux-s390@vger.kernel.org, Eric Farman <farman@linux.ibm.com>,
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	Farhan Ali <alifm@linux.ibm.com>, qemu-devel@nongnu.org,
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To: Pierre Morel <pmorel@linux.ibm.com>
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On Thu, 24 Jan 2019 11:08:02 +0100
Pierre Morel <pmorel@linux.ibm.com> wrote:

> On 23/01/2019 11:21, Cornelia Huck wrote:
> > On Tue, 22 Jan 2019 19:33:46 +0100
> > Halil Pasic <pasic@linux.ibm.com> wrote:
> >   
> >> On Mon, 21 Jan 2019 12:03:51 +0100
> >> Cornelia Huck <cohuck@redhat.com> wrote:
> >>  
> >>> --- a/drivers/s390/cio/vfio_ccw_private.h
> >>> +++ b/drivers/s390/cio/vfio_ccw_private.h
> >>> @@ -28,6 +28,7 @@
> >>>    * @mdev: pointer to the mediated device
> >>>    * @nb: notifier for vfio events
> >>>    * @io_region: MMIO region to input/output I/O arguments/results
> >>> + * @io_mutex: protect against concurrent update of I/O structures  
> >>
> >> We could be a bit more specific about what does this mutex guard.
> >> Is it only io_region, or cp, irb and the new regions a well? ->state does
> >> not seem to be covered, but should need some sort of synchronisation
> >> too, or?  
> > 
> > I'm not sure. IIRC Pierre had some ideas about locking in the fsm?
> >   
> 
> Yes I postponed this work to not collide with your patch series.
> 
> Do you think I should provide a new version of the FSM reworking series 
> based on the last comment I got?
> 
> I would take into account that the asynchronous commands will come with 
> your patch series and only provide the framework changes.

This was more an answer to Halil's concerns around state
synchronization. I would prefer to first get this series (or a
variation) into decent shape, and then address state machine handling
on top of that (when we know more about the transitions involved), just
to avoid confusion.

Does that sound reasonable?