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.
Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
---
drivers/iommu/iommufd/selftest.c | 39 +++++++++++++++++++++++++-------
1 file changed, 31 insertions(+), 8 deletions(-)
diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c
index 92d753985640..4f67a83f667a 100644
--- a/drivers/iommu/iommufd/selftest.c
+++ b/drivers/iommu/iommufd/selftest.c
@@ -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);
--
2.43.0
