Re: [PATCH v2 7/9] vfio/ccw: Remove private->mdev

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Sep 24, 2021 at 04:45:02PM -0400, Eric Farman wrote:
> On Thu, 2021-09-09 at 16:38 -0300, Jason Gunthorpe wrote:
> > Having a mdev pointer floating about in addition to a struct
> > vfio_device
> > is confusing. It is only used for three things:
> > 
> > - Getting the mdev 'struct device *' - this is the same as
> >      private->vdev.dev
> > 
> > - Printing the uuid of the mdev in logging. The uuid is also the
> > dev_name
> >   of the mdev so this is the same string as
> >      dev_name(private->vdev.dev)
> > 
> > - A weird attempt to fence the vfio_ccw_sch_io_todo() work. This work
> > is
> >   only queued during states IDLE/PROCESSING/PENDING and flushed when
> >   entering CLOSED. Thus the work already cannot run when the mdev is
> > NULL.
> >   Remove it.
> > 
> > Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> >  drivers/s390/cio/vfio_ccw_drv.c     |  6 ++--
> >  drivers/s390/cio/vfio_ccw_fsm.c     | 48 +++++++++++++------------
> >  drivers/s390/cio/vfio_ccw_ops.c     | 16 ++++------
> >  drivers/s390/cio/vfio_ccw_private.h |  2 --
> >  include/linux/mdev.h                |  4 ---
> >  5 files changed, 30 insertions(+), 46 deletions(-)
> 
> I like this patch. Unfortunately it depends on the removal of a hunk in
> patch 4, which sets the FSM state to different values based on whether
> private->mdev is NULL or not, so can't go on its own. Need to spend
> more time thinking about that patch.

The FSM patch is important, really what is happening is the FSM logic
takes on the roles that was being split all over the place with other
logic, like this mdev stuff. To make that work we need a FSM that
makes sense..

Jason