On Wed, Feb 17, 2016 at 11:16:10AM -0500, Waiman Long wrote: > >So why not use RCU for the list iteration and avoid potentially large > >lock hold times? > > > > I know we can use RCU for singly linked list, but I don't think we can use > that for doubly linked list as there is no easy way to make atomic changes > to both prev and next pointers simultaneously unless you are taking about > 16b cmpxchg which is only supported in some architecture.
See include/linux/rculist.h, the only constraint is that reverse iteration is not allowed, because of what you say.
