v4l2 framework in a multiple thread environment

Hi, I am writing a driver using v4l2 framework. I want to know does v4l2 framework make my driver thread-safe? What if multiple threads try to * open the driver * enqueue/dequeue buffer * run device_run at the same time. Do I need to add mutex myself? Of all the hooks I provide to v4l2 framework is already thread-safe? Thank you.