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[v7,11/19] iommufd: Fix locking around hwpt allocation

Message ID 11-v7-6c0fd698eda2+5e3-iommufd_alloc_jgg@nvidia.com
State Superseded
Headers show
Series Add iommufd physical device operations for replace and alloc hwpt | expand

Commit Message

Jason Gunthorpe May 15, 2023, 2 p.m. UTC 
Due to the auto_domains mechanism the ioas->mutex must be held until
the hwpt is completely setup by iommufd_object_abort_and_destroy() or
iommufd_object_finalize().

This prevents a concurrent iommufd_device_auto_get_domain() from seeing
an incompletely initialized object through the ioas->hwpt_list.

To make this more consistent move the unlock until after finalize.

Fixes: e8d57210035b ("iommufd: Add kAPI toward external drivers for physical devices")
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/iommu/iommufd/device.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 2eec53c5d00e74..dc437409e70ffe 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -398,8 +398,8 @@  static int iommufd_device_auto_get_domain(struct iommufd_device *idev,
 	hwpt->auto_domain = true;
 	*pt_id = hwpt->obj.id;
 
-	mutex_unlock(&ioas->mutex);
 	iommufd_object_finalize(idev->ictx, &hwpt->obj);
+	mutex_unlock(&ioas->mutex);
 	return 0;
 out_unlock:
 	mutex_unlock(&ioas->mutex);