[PATCH v3 06/23] iommufd/driver: Add iommufd_struct_destroy to revert iommufd_viommu_alloc

[Nicolin Chen]

An IOMMU driver that allocated a vIOMMU may want to revert the allocation,
if it encounters an internal error after the allocation. So, there needs a
destroy helper for drivers to use. For instance:

static my_viommu_alloc()
{
	...
	my_viommu = iommufd_viommu_alloc(viomm, struct my_viommu, core);
	...
	ret = init_my_viommu();
	if (ret) {
		/* Need to destroy the my_viommu->core */
		return ERR_PTR(ret);
	}
	return &my_viommu->core;
}

Move iommufd_object_abort() to the driver.c file and the public header, to
introduce common iommufd_struct_destroy() helper that will abort all kinds
of driver structures, not confined to iommufd_viommu but also the new ones
being added in the future.

Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
---
 drivers/iommu/iommufd/iommufd_private.h |  1 -
 include/linux/iommufd.h                 | 16 ++++++++++++++++
 drivers/iommu/iommufd/driver.c          | 14 ++++++++++++++
 drivers/iommu/iommufd/main.c            | 13 -------------
 4 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 5c69ac05c029..8d96aa514033 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -180,7 +180,6 @@ static inline void iommufd_put_object(struct iommufd_ctx *ictx,
 		wake_up_interruptible_all(&ictx->destroy_wait);
 }
 
-void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj);
 void iommufd_object_abort_and_destroy(struct iommufd_ctx *ictx,
 				      struct iommufd_object *obj);
 void iommufd_object_finalize(struct iommufd_ctx *ictx,
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index dc6535e848df..f6f333eaaae3 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -213,6 +213,7 @@ static inline int iommufd_vfio_compat_set_no_iommu(struct iommufd_ctx *ictx)
 struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx,
 					     size_t size,
 					     enum iommufd_object_type type);
+void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj);
 struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
 				       unsigned long vdev_id);
 int iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
@@ -228,6 +229,11 @@ _iommufd_object_alloc(struct iommufd_ctx *ictx, size_t size,
 	return ERR_PTR(-EOPNOTSUPP);
 }
 
+static inline void iommufd_object_abort(struct iommufd_ctx *ictx,
+					struct iommufd_object *obj)
+{
+}
+
 static inline struct device *
 iommufd_viommu_find_dev(struct iommufd_viommu *viommu, unsigned long vdev_id)
 {
@@ -285,4 +291,14 @@ static inline int iommufd_viommu_report_event(struct iommufd_viommu *viommu,
 		}                                                              \
 		ret;                                                           \
 	})
+
+/* Helper for IOMMU driver to destroy structures created by allocators above */
+#define iommufd_struct_destroy(drv_struct, member)                             \
+	({                                                                     \
+		static_assert(__same_type(struct iommufd_object,               \
+					  drv_struct->member.obj));            \
+		static_assert(offsetof(typeof(*drv_struct), member.obj) == 0); \
+		iommufd_object_abort(drv_struct->member.ictx,                  \
+				     &drv_struct->member.obj);                 \
+	})
 #endif
diff --git a/drivers/iommu/iommufd/driver.c b/drivers/iommu/iommufd/driver.c
index 922cd1fe7ec2..7980a09761c2 100644
--- a/drivers/iommu/iommufd/driver.c
+++ b/drivers/iommu/iommufd/driver.c
@@ -36,6 +36,20 @@ struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx,
 }
 EXPORT_SYMBOL_NS_GPL(_iommufd_object_alloc, "IOMMUFD");
 
+/* Undo _iommufd_object_alloc() if iommufd_object_finalize() was not called */
+void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj)
+{
+	XA_STATE(xas, &ictx->objects, obj->id);
+	void *old;
+
+	xa_lock(&ictx->objects);
+	old = xas_store(&xas, NULL);
+	xa_unlock(&ictx->objects);
+	WARN_ON(old != XA_ZERO_ENTRY);
+	kfree(obj);
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_object_abort, "IOMMUFD");
+
 /* Caller should xa_lock(&viommu->vdevs) to protect the return value */
 struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
 				       unsigned long vdev_id)
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 3df468f64e7d..2b9ee9b4a424 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -51,19 +51,6 @@ void iommufd_object_finalize(struct iommufd_ctx *ictx,
 	WARN_ON(old != XA_ZERO_ENTRY);
 }
 
-/* Undo _iommufd_object_alloc() if iommufd_object_finalize() was not called */
-void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj)
-{
-	XA_STATE(xas, &ictx->objects, obj->id);
-	void *old;
-
-	xa_lock(&ictx->objects);
-	old = xas_store(&xas, NULL);
-	xa_unlock(&ictx->objects);
-	WARN_ON(old != XA_ZERO_ENTRY);
-	kfree(obj);
-}
-
 /*
  * Abort an object that has been fully initialized and needs destroy, but has
  * not been finalized.
-- 
2.43.0