RE: [PATCH 03/14] iommufd: Replace the hwpt->devices list with iommufd_group

Tian, Kevin
2023-03-02T08:02:32Z

> From: Jason Gunthorpe <jgg@nvidia.com>
> 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?