> From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Saturday, February 25, 2023 8:28 AM > > +struct iommufd_hw_pagetable * > +iommufd_hw_pagetable_detach(struct iommufd_device *idev) > { > - if (!iommufd_hw_pagetable_has_group(hwpt, idev->igroup)) > + struct iommufd_hw_pagetable *hwpt = idev->igroup->hwpt; > + > + lockdep_assert_held(&idev->igroup->lock); > + > + idev->igroup->devices--; > + if (!idev->igroup->devices) { > iommu_detach_group(hwpt->domain, idev->igroup->group); > + idev->igroup->hwpt = NULL; hwpt->obj.users should be decremented here instead of leaving it in iommufd_device_detach(). > void iommufd_device_detach(struct iommufd_device *idev) > { > - struct iommufd_hw_pagetable *hwpt = idev->hwpt; > + struct iommufd_hw_pagetable *hwpt; > > - mutex_lock(&hwpt->devices_lock); > - list_del(&idev->devices_item); > - idev->hwpt = NULL; > - iommufd_hw_pagetable_detach(hwpt, idev); > - mutex_unlock(&hwpt->devices_lock); > + mutex_lock(&idev->igroup->lock); > + hwpt = iommufd_hw_pagetable_detach(idev); the only parameter is idev while the name is called hw_pagetable_xxx. is it cleaner to get hwpt here and then pass into the detach function?