Commit 86070569 authored by Nicolin Chen's avatar Nicolin Chen Committed by Jason Gunthorpe
Browse files

iommufd/selftest: Add refcount to mock_iommu_device 

For an iommu_dev that can unplug (so far only this selftest does so), the
viommu->iommu_dev pointer has no guarantee of its life cycle after it is
copied from the idev->dev->iommu->iommu_dev.

Track the user count of the iommu_dev. Postpone the exit routine using a
completion, if refcount is unbalanced. The refcount inc/dec will be added
in the following patch.

Link: https://patch.msgid.link/r/33f28d64841b497eebef11b49a571e03103c5d24.1730836219.git.nicolinc@nvidia.com


Suggested-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: default avatarNicolin Chen <nicolinc@nvidia.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent 18f81990

drivers/iommu/iommufd/selftest.c

+31 −8
Original line number Diff line number Diff line
@@ -533,14 +533,17 @@ static bool mock_domain_capable(struct device *dev, enum iommu_cap cap) 


static struct iopf_queue *mock_iommu_iopf_queue;



static struct iommu_device mock_iommu_device = {

};

static struct mock_iommu_device {

	struct iommu_device iommu_dev;

	struct completion complete;

	refcount_t users;

} mock_iommu;



static struct iommu_device *mock_probe_device(struct device *dev)

{

	if (dev->bus != &iommufd_mock_bus_type.bus)

		return ERR_PTR(-ENODEV);

	return &mock_iommu_device;

	return &mock_iommu.iommu_dev;

}



static void mock_domain_page_response(struct device *dev, struct iopf_fault *evt,
@@ -1556,24 +1559,27 @@ int __init iommufd_test_init(void) 
	if (rc)

		goto err_platform;



	rc = iommu_device_sysfs_add(&mock_iommu_device,

	rc = iommu_device_sysfs_add(&mock_iommu.iommu_dev,

				    &selftest_iommu_dev->dev, NULL, "%s",

				    dev_name(&selftest_iommu_dev->dev));

	if (rc)

		goto err_bus;



	rc = iommu_device_register_bus(&mock_iommu_device, &mock_ops,

	rc = iommu_device_register_bus(&mock_iommu.iommu_dev, &mock_ops,

				  &iommufd_mock_bus_type.bus,

				  &iommufd_mock_bus_type.nb);

	if (rc)

		goto err_sysfs;



	refcount_set(&mock_iommu.users, 1);

	init_completion(&mock_iommu.complete);



	mock_iommu_iopf_queue = iopf_queue_alloc("mock-iopfq");



	return 0;



err_sysfs:

	iommu_device_sysfs_remove(&mock_iommu_device);

	iommu_device_sysfs_remove(&mock_iommu.iommu_dev);

err_bus:

	bus_unregister(&iommufd_mock_bus_type.bus);

err_platform:
@@ -1583,6 +1589,22 @@ int __init iommufd_test_init(void) 
	return rc;

}



static void iommufd_test_wait_for_users(void)

{

	if (refcount_dec_and_test(&mock_iommu.users))

		return;

	/*

	 * Time out waiting for iommu device user count to become 0.

	 *

	 * Note that this is just making an example here, since the selftest is

	 * built into the iommufd module, i.e. it only unplugs the iommu device

	 * when unloading the module. So, it is expected that this WARN_ON will

	 * not trigger, as long as any iommufd FDs are open.

	 */

	WARN_ON(!wait_for_completion_timeout(&mock_iommu.complete,

					     msecs_to_jiffies(10000)));

}



void iommufd_test_exit(void)

{

	if (mock_iommu_iopf_queue) {
@@ -1590,8 +1612,9 @@ void iommufd_test_exit(void) 
		mock_iommu_iopf_queue = NULL;

	}



	iommu_device_sysfs_remove(&mock_iommu_device);

	iommu_device_unregister_bus(&mock_iommu_device,

	iommufd_test_wait_for_users();

	iommu_device_sysfs_remove(&mock_iommu.iommu_dev);

	iommu_device_unregister_bus(&mock_iommu.iommu_dev,

				    &iommufd_mock_bus_type.bus,

				    &iommufd_mock_bus_type.nb);

	bus_unregister(&iommufd_mock_bus_type.bus);