Re: [PATCH 1/5] [RFC] Add volatile range management code

Michel Lespinasse
2012-08-09T09:46:39Z

On Fri, Jul 27, 2012 at 8:57 PM, John Stultz <john.stultz@linaro.org> wrote:
> v5:
> * Drop intervaltree for prio_tree usage per Michel &
> Dmitry's suggestions.

Actually, I believe the ranges you need to track are non-overlapping, correct ?

If that is the case, a simple rbtree, sorted by start-of-range
address, would work best.
(I am trying to remove prio_tree users... :)

> + /* First, find any existing intervals that overlap */
> + prio_tree_iter_init(&iter, root, start, end);

Note that prio tree iterations take intervals as [start; last] not [start; end[
So if you want to stick with prio trees, you would have to use end-1 here.

> + /* Coalesce left-adjacent ranges */
> + prio_tree_iter_init(&iter, root, start-1, start);

Same here; you probably want to use start-1 on both ends

> + node = prio_tree_next(&iter);
> + while (node) {

I'm confused, I don't think you ever expect more than one range to
match, do you ???

> + /* Coalesce right-adjacent ranges */
> + prio_tree_iter_init(&iter, root, end, end+1);

Same again, here you probably want end on both ends

This is far from a complete code review, but I just wanted to point
out a couple details that jumped to me first. I am afraid I am missing
some of the background about how the feature is to be used to really
dig into the rest of the changes at this point :/

--
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.