On Thu, Mar 02, 2023 at 08:01:00AM +0000, Tian, Kevin wrote:
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().
It is like this because eventually we can't call iommufd_object_destroy_user() while holding the locks.
So the lowest function returns the hwpt up the call chain and once everything is unlocked then it calls iommufd_hw_pagetable_put()
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?
Not really, the function needs three members of the idev to work.
The pair'd attach function is:
int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt, struct iommufd_device *idev)
So I think it would be very unclear to change the name, and this is more a hw_pagetable operation than a device operation.
Jason