Mechnism for sharing data between kernel and user space

Hi All, I am exploring the mechanism for sharing data between kernel and user space. There are following mechanism I have found 1. copy_to_user/copy_from_user 2. Netlink sock 3. /proc, /debugfs etc. Other than this, Is there any efficient way of which I could read/write linked-list that I have created from my kernel module. --- Jitendra