linux-kernel - RE: [PATCH v2 09/14] vfio-iommufd: Add detach

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Message-ID: <DS0PR11MB75299F77D98FAF3FF197A304C3DB9@DS0PR11MB7529.namprd11.prod.outlook.com>
Date:   Tue, 7 Feb 2023 08:56:48 +0000
From:   "Liu, Yi L" <yi.l.liu@...el.com>
To:     "Tian, Kevin" <kevin.tian@...el.com>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "jgg@...dia.com" <jgg@...dia.com>
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        "eric.auger@...hat.com" <eric.auger@...hat.com>,
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        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
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Subject: RE: [PATCH v2 09/14] vfio-iommufd: Add detach_ioas support for
 physical VFIO devices

> From: Tian, Kevin <kevin.tian@...el.com>
> Sent: Tuesday, February 7, 2023 2:07 PM
> 
> > From: Liu, Yi L <yi.l.liu@...el.com>
> > Sent: Monday, February 6, 2023 5:05 PM
> >
> > +static void __vfio_iommufd_detach(struct vfio_device *vdev)
> > +{
> > +	iommufd_device_detach(vdev->iommufd_device);
> > +	vdev->iommufd_attached = false;
> > +}
> > +
> >  void vfio_iommufd_physical_unbind(struct vfio_device *vdev)
> >  {
> >  	lockdep_assert_held(&vdev->dev_set->lock);
> >
> > -	if (vdev->iommufd_attached) {
> > -		iommufd_device_detach(vdev->iommufd_device);
> > -		vdev->iommufd_attached = false;
> > -	}
> > +	if (vdev->iommufd_attached)
> > +		__vfio_iommufd_detach(vdev);
> 
> I'm not sure whether this abstraction really improves things.
> 
> Just two callers. and the old code reads clearer to me which
> checks a flag, does something and then clear the flag.

Ok. Will revert it.

> 
> > @@ -74,6 +74,7 @@ struct vfio_device {
> >   * @unbind_iommufd: Opposite of bind_iommufd
> >   * @attach_ioas: Called when attaching device to an IOAS/HWPT
> managed
> > by the
> >   *		 bound iommufd. Undo in unbind_iommufd.
> 
> "Undo in unbind_iommufd if @detach_ioas is not called".
>
> > + * @detach_ioas: Opposite of attach_ioas, this is for runtime undo.
> 
> remove "this is for runtime undo" which is confusing.

Ok, clear with your above suggestion.

Regards,
Yi Liu