list: add rare_write() list helpers

Some structures that are intended to be made write-rarely are designed to
be linked by lists. As a result, there need to be rare_write()-supported
linked list primitives.

As found in PaX, this adds list management helpers for doing updates to
rarely-changed lists.

Signed-off-by: Kees Cook <keescook@chromium.org>
3 files changed