iommufd: Do not allow _iommufd_object_alloc_ucmd if abort op is set

An abort op was introduced to allow its caller to invoke it within a lock
in the caller's function. On the other hand, _iommufd_object_alloc_ucmd()
would invoke the abort op in iommufd_object_abort_and_destroy() that must
be outside the caller's lock. So, these two cannot work together.

Add a validation in the _iommufd_object_alloc_ucmd(). Pick -EOPNOTSUPP to
reject the function call, indicating that the object allocator is buggy.

Link: https://patch.msgid.link/r/20250710202354.1658511-1-nicolinc@nvidia.com
Suggested-by: Xu Yilun <yilun.xu@linux.intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Xu Yilun <yilun.xu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 0fb81a905cb134ff44bf15b8a87f0e4989fe3efe..69c2195e77cad7e7e3941aa03b75c9e334c7de89 100644 (file)
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -71,6 +71,15 @@ struct iommufd_object *_iommufd_object_alloc_ucmd(struct iommufd_ucmd *ucmd,
        if (WARN_ON(ucmd->new_obj))
                return ERR_PTR(-EBUSY);
 
+       /*
+        * An abort op means that its caller needs to invoke it within a lock in
+        * the caller. So it doesn't work with _iommufd_object_alloc_ucmd() that
+        * will invoke the abort op in iommufd_object_abort_and_destroy(), which
+        * must be outside the caller's lock.
+        */
+       if (WARN_ON(iommufd_object_ops[type].abort))
+               return ERR_PTR(-EOPNOTSUPP);
+
        new_obj = _iommufd_object_alloc(ucmd->ictx, size, type);
        if (IS_ERR(new_obj))
                return new_obj;