Re: [Qemu-devel] [PATCH v2 2/5] vfio-ccw: concurrent I/O handling

[Cornelia Huck]

On Tue, 22 Jan 2019 19:33:46 +0100
Halil Pasic <address@hidden> wrote:

> On Mon, 21 Jan 2019 12:03:51 +0100
> Cornelia Huck <address@hidden> 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?

> 
> >   * @cp: channel program for the current I/O operation
> >   * @irb: irb info received from interrupt
> >   * @scsw: scsw info
> > @@ -42,6 +43,7 @@ struct vfio_ccw_private {
> >     struct mdev_device      *mdev;
> >     struct notifier_block   nb;
> >     struct ccw_io_region    *io_region;
> > +   struct mutex            io_mutex;
> >  
> >     struct channel_program  cp;
> >     struct irb              irb;
> > --   
>