From: Jason Gunthorpe <jgg@nvidia.com>
Date: Mon, 13 Feb 2023 14:02:42 -0400
Subject: [PATCH] iommufd: Do not add the same hwpt to the ioas->hwpt_list
 twice
References: bsc#1012628
Patch-mainline: 6.2.3
Git-commit: b4ff830eca097df51af10a9be29e8cc817327919

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>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/iommu/iommufd/device.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index d81f93a3..f6f42d8b 100644
--- 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: {
-- 
2.35.3