Re: [PATCH v6 01/11] iommu: Add dma ownership management interfaces

Jason Gunthorpe
2022-02-23T18:33:04Z

On Wed, Feb 23, 2022 at 06:20:36PM +0000, Robin Murphy wrote:
> On 2022-02-23 18:02, Jason Gunthorpe via iommu wrote:
> > On Wed, Feb 23, 2022 at 06:00:06PM +0000, Robin Murphy wrote:
> >
> > > ...and equivalently just set owner_cnt directly to 0 here. I don't see a
> > > realistic use-case for any driver to claim the same group more than once,
> > > and allowing it in the API just feels like opening up various potential
> > > corners for things to get out of sync.
> >
> > I am Ok if we toss it out to get this merged, as there is no in-kernel
> > user right now.
> >
> > Something will have to come back for iommufd, but we can look at what
> > is best suited then.
>
> If iommufd plans to be too dumb to keep track of whether it already owns a
> given group or not, I can't see it dealing with attaching that group to a
> single domain no more than once, either ;)

Indeed, this is why I'd like to use the device API :)

Jason