vdpa: factor out vdpa_set_features_unlocked for vdpa internal use

No functional change introduced. vdpa bus driver such as virtio_vdpa
or vhost_vdpa is not supposed to take care of the locking for core
by its own. The locked API vdpa_set_features should suffice the
bus driver's need.

Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/1642206481-30721-2-git-send-email-si-wei.liu@oracle.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

drivers/vdpa/vdpa.c

@@ -393,7 +393,7 @@ static void vdpa_get_config_unlocked(struct vdpa_device *vdev,
 	 * If it does happen we assume a legacy guest.
 	 */
 	if (!vdev->features_valid)
-		vdpa_set_features(vdev, 0, true);
+		vdpa_set_features_unlocked(vdev, 0);
 	ops->get_config(vdev, offset, buf, len);
 }
 

drivers/vhost/vdpa.c

@@ -286,7 +286,7 @@ static long vhost_vdpa_set_features(struct vhost_vdpa *v, u64 __user *featurep)
 	if (copy_from_user(&features, featurep, sizeof(features)))
 		return -EFAULT;
 
-	if (vdpa_set_features(vdpa, features, false))
+	if (vdpa_set_features(vdpa, features))
 		return -EINVAL;
 
 	return 0;

drivers/virtio/virtio_vdpa.c

@@ -317,7 +317,7 @@ static int virtio_vdpa_finalize_features(struct virtio_device *vdev)
 	/* Give virtio_ring a chance to accept features. */
 	vring_transport_features(vdev);
 
-	return vdpa_set_features(vdpa, vdev->features, false);
+	return vdpa_set_features(vdpa, vdev->features);
 }
 
 static const char *virtio_vdpa_bus_name(struct virtio_device *vdev)

include/linux/vdpa.h

@@ -401,18 +401,24 @@ static inline int vdpa_reset(struct vdpa_device *vdev)
 	return ret;
 }
 
-static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features, bool locked)
+static inline int vdpa_set_features_unlocked(struct vdpa_device *vdev, u64 features)
 {
 	const struct vdpa_config_ops *ops = vdev->config;
 	int ret;
 
-	if (!locked)
-		mutex_lock(&vdev->cf_mutex);
-
 	vdev->features_valid = true;
 	ret = ops->set_driver_features(vdev, features);
-	if (!locked)
-		mutex_unlock(&vdev->cf_mutex);
+
+	return ret;
+}
+
+static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features)
+{
+	int ret;
+
+	mutex_lock(&vdev->cf_mutex);
+	ret = vdpa_set_features_unlocked(vdev, features);
+	mutex_unlock(&vdev->cf_mutex);
 
 	return ret;
 }