drm: Push dirtyfb ioctl kms locking down to drivers

Not all drivers will need take all the modeset locks for dirtyfb, so
push the locking down to the drivers.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c
index 97e9d61..dbadd49 100644
--- a/drivers/gpu/drm/udl/udl_fb.c
+++ b/drivers/gpu/drm/udl/udl_fb.c
@@ -403,15 +403,17 @@
 	int i;
 	int ret = 0;
 
+	drm_modeset_lock_all(fb->dev);
+
 	if (!ufb->active_16)
-		return 0;
+		goto unlock;
 
 	if (ufb->obj->base.import_attach) {
 		ret = dma_buf_begin_cpu_access(ufb->obj->base.import_attach->dmabuf,
 					       0, ufb->obj->base.size,
 					       DMA_FROM_DEVICE);
 		if (ret)
-			return ret;
+			goto unlock;
 	}
 
 	for (i = 0; i < num_clips; i++) {
@@ -419,7 +421,7 @@
 				  clips[i].x2 - clips[i].x1,
 				  clips[i].y2 - clips[i].y1);
 		if (ret)
-			break;
+			goto unlock;
 	}
 
 	if (ufb->obj->base.import_attach) {
@@ -427,6 +429,10 @@
 				       0, ufb->obj->base.size,
 				       DMA_FROM_DEVICE);
 	}
+
+ unlock:
+	drm_modeset_unlock_all(fb->dev);
+
 	return ret;
 }