media: v4l2-ctrls: v4l2_ctrl_request_complete() should always set ref->req

When the request is completed, all controls are copied to the request object.
However, when VIDIOC_G_EXT_CTRLS attempts to read control values from the
request it will read the current value instead for any control reference that
has a NULL ref->req pointer. But that's wrong: after completing the request
*all* controls should have a non-NULL ref->req pointer since they are after
all copied to the request.

So set ref->req if it wasn't set already.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reported-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/v4l2-core/v4l2-ctrls.c

@@ -4296,10 +4296,17 @@ void v4l2_ctrl_request_complete(struct media_request *req,
 			continue;
 
 		v4l2_ctrl_lock(ctrl);
-		if (ref->req)
+		if (ref->req) {
 			ptr_to_ptr(ctrl, ref->req->p_req, ref->p_req);
-		else
+		} else {
 			ptr_to_ptr(ctrl, ctrl->p_cur, ref->p_req);
+			/*
+			 * Set ref->req to ensure that when userspace wants to
+			 * obtain the controls of this request it will take
+			 * this value and not the current value of the control.
+			 */
+			ref->req = ref;
+		}
 		v4l2_ctrl_unlock(ctrl);
 	}