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

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?