Re: [PATCH 06/14] iommufd: Move putting a hwpt to a helper function

Jason Gunthorpe
2023-03-06T20:29:52Z

On Thu, Mar 02, 2023 at 08:12:28AM +0000, Tian, Kevin wrote:
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Saturday, February 25, 2023 8:28 AM
> >
> > @@ -481,11 +481,7 @@ void iommufd_device_detach(struct
> > iommufd_device *idev)
> > hwpt = iommufd_hw_pagetable_detach(idev);
> > mutex_unlock(&idev->igroup->lock);
> >
> > - if (hwpt->auto_domain)
> > - iommufd_object_destroy_user(idev->ictx, &hwpt->obj);
> > - else
> > - refcount_dec(&hwpt->obj.users);
> > -
> > + iommufd_hw_pagetable_put(idev->ictx, hwpt);
> > refcount_dec(&idev->obj.users);
> > }
>
> As commented in patch3 this should be called in
> iommufd_hw_pagetable_detach() when idev->igroup->hwpt is cleared.

Same answer, has to be called after we unlock everything. The issue is
not device_detach which has simple locking but
iommufd_device_change_pt() in a later patch.

Jason