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iommufd/selftest: Add refcount to mock_iommu_device

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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: 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>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Nicolin Chen
2024-11-05 12:04:26 -08:00
committed by Jason Gunthorpe
parent 18f819901d
commit 8607056945
1 changed files with 31 additions and 8 deletions
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39
drivers/iommu/iommufd/selftest.c
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@@ -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);