iommufd: Do not add the same hwpt to the ioas->hwpt_list twice

commit b4ff830eca097df51af10a9be29e8cc817327919 upstream.

The hwpt is added to the hwpt_list only during its creation, it is never
added again. This hunk is some missed leftover from rework. Adding it
twice will corrupt the linked list in some cases.

It effects HWPT specific attachment, which is something the test suite
cannot cover until we can create a legitimate struct device with a
non-system iommu "driver" (ie we need the bus removed from the iommu code)

Cc: stable@vger.kernel.org
Fixes: e8d57210035b ("iommufd: Add kAPI toward external drivers for physical devices")
Link: https://lore.kernel.org/r/1-v1-4336b5cb2fe4+1d7-iommufd_hwpt_jgg@nvidia.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reported-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index d81f93a321afcb7a79e5e69cb755ff008ab96f6b..f6f42d8bc8ad88a1e996231f8c410c510076bb4c 100644 (file)
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -346,10 +346,6 @@ int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id)
                rc = iommufd_device_do_attach(idev, hwpt);
                if (rc)
                        goto out_put_pt_obj;
-
-               mutex_lock(&hwpt->ioas->mutex);
-               list_add_tail(&hwpt->hwpt_item, &hwpt->ioas->hwpt_list);
-               mutex_unlock(&hwpt->ioas->mutex);
                break;
        }
        case IOMMUFD_OBJ_IOAS: {