vfio/mdev: Expose mdev_get/put_parent to mdev_private.h

The next patch will use these in mdev_sysfs.c

While here remove the now dead code checks for NULL, a mdev_type can never
have a NULL parent.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <6-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/mdev/mdev_core.c

@@ -45,7 +45,7 @@ static struct mdev_parent *__find_parent_device(struct device *dev)
 	return NULL;
 }
 
-static void mdev_release_parent(struct kref *kref)
+void mdev_release_parent(struct kref *kref)
 {
 	struct mdev_parent *parent = container_of(kref, struct mdev_parent,
 						  ref);
@@ -55,20 +55,6 @@ static void mdev_release_parent(struct kref *kref)
 	put_device(dev);
 }
 
-static struct mdev_parent *mdev_get_parent(struct mdev_parent *parent)
-{
-	if (parent)
-		kref_get(&parent->ref);
-
-	return parent;
-}
-
-static void mdev_put_parent(struct mdev_parent *parent)
-{
-	if (parent)
-		kref_put(&parent->ref, mdev_release_parent);
-}
-
 /* Caller must hold parent unreg_sem read or write lock */
 static void mdev_device_remove_common(struct mdev_device *mdev)
 {
@@ -243,12 +229,9 @@ int mdev_device_create(struct mdev_type *type, const guid_t *uuid)
 {
 	int ret;
 	struct mdev_device *mdev, *tmp;
-	struct mdev_parent *parent;
-
-	parent = mdev_get_parent(type->parent);
-	if (!parent)
-		return -EINVAL;
+	struct mdev_parent *parent = type->parent;
 
+	mdev_get_parent(parent);
 	mutex_lock(&mdev_list_lock);
 
 	/* Check for duplicate */

drivers/vfio/mdev/mdev_private.h

@@ -46,4 +46,16 @@ void mdev_remove_sysfs_files(struct mdev_device *mdev);
 int mdev_device_create(struct mdev_type *kobj, const guid_t *uuid);
 int  mdev_device_remove(struct mdev_device *dev);
 
+void mdev_release_parent(struct kref *kref);
+
+static inline void mdev_get_parent(struct mdev_parent *parent)
+{
+	kref_get(&parent->ref);
+}
+
+static inline void mdev_put_parent(struct mdev_parent *parent)
+{
+	kref_put(&parent->ref, mdev_release_parent);
+}
+
 #endif /* MDEV_PRIVATE_H */