Re: [PATCH] vfio-ccw: Attempt to clean up all IRQs on error

[Eric Farman]

On Wed, 2021-04-28 at 12:37 +0200, Cornelia Huck wrote:
> On Tue, 27 Apr 2021 16:25:11 +0200
> Eric Farman <farman@linux.ibm.com> wrote:
> 
> > The vfio_ccw_unrealize() routine makes an unconditional attempt to
> > unregister every IRQ notifier, though they may not have been
> > registered
> > in the first place (when running on an older kernel, for example).
> > 
> > Let's mirror this behavior in the error cleanups in
> > vfio_ccw_realize()
> > so that if/when new IRQs are added, it is less confusing to
> > recognize
> > the necessary procedures. The worst case scenario would be some
> > extra
> > messages about an undefined IRQ, but since this is an error exit
> > that
> > won't be the only thing to worry about.
> 
> I'm wondering whether we should downgrade the moan during unregister
> from error to warn; the code deals with it gracefully, and we're not
> losing any functionality.

Ha, I thought it already was a warning. I think that's a good idea, let
me spin a quick v2.

> 
> Patch looks good.

Thanks,
Eric

> 
> > Signed-off-by: Eric Farman <farman@linux.ibm.com>
> > ---
> >  hw/vfio/ccw.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> > index 400bc07fe2..169438c3b8 100644
> > --- a/hw/vfio/ccw.c
> > +++ b/hw/vfio/ccw.c
> > @@ -690,7 +690,7 @@ static void vfio_ccw_realize(DeviceState *dev,
> > Error **errp)
> >      if (vcdev->crw_region) {
> >          vfio_ccw_register_irq_notifier(vcdev,
> > VFIO_CCW_CRW_IRQ_INDEX, &err);
> >          if (err) {
> > -            goto out_crw_notifier_err;
> > +            goto out_irq_notifier_err;
> >          }
> >      }
> >  
> > @@ -705,7 +705,9 @@ static void vfio_ccw_realize(DeviceState *dev,
> > Error **errp)
> >  
> >      return;
> >  
> > -out_crw_notifier_err:
> > +out_irq_notifier_err:
> > +    vfio_ccw_unregister_irq_notifier(vcdev,
> > VFIO_CCW_REQ_IRQ_INDEX);
> > +    vfio_ccw_unregister_irq_notifier(vcdev,
> > VFIO_CCW_CRW_IRQ_INDEX);
> >      vfio_ccw_unregister_irq_notifier(vcdev,
> > VFIO_CCW_IO_IRQ_INDEX);
> >  out_io_notifier_err:
> >      vfio_ccw_put_region(vcdev);