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@nvidia.com Reviewed-by: Kevin Tian kevin.tian@intel.com Reviewed-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Nicolin Chen nicolinc@nvidia.com --- 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);