On Thu, Mar 23, 2023 at 07:25:55AM +0000, Tian, Kevin wrote:
> > From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> > Sent: Wednesday, March 22, 2023 3:15 AM
> > +int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id)
> > +{
> > + int rc;
> > +
> > + rc = iommufd_device_change_pt(idev, pt_id,
> > &iommufd_device_do_attach);
> > + if (rc)
> > + return rc;
> > +
> > + /*
> > + * Pairs with iommufd_device_detach() - catches caller bugs
> > attempting
> > + * to destroy a device with an attachment.
> > + */
> > + refcount_inc(&idev->obj.users);
> > + return 0;
>
> While it's the right thing to do I'm not sure what "catch caller bugs"
> mean here. There is no WARN_ON to catch.
The WARN_ON is on the destroy path of the device
was_destroyed = iommufd_object_destroy_user(idev->ictx, &idev->obj);
WARN_ON(!was_destroyed);
It is the idev we are incr'ing
Jason
