> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Saturday, November 5, 2022 3:38 AM
>
> On Thu, Nov 03, 2022 at 05:31:17AM +0000, Tian, Kevin wrote:
> > > From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> > > Sent: Wednesday, October 26, 2022 2:12 AM
> > > +/*
> > > + * This iterator travels over spans in an interval tree. It does not return
> > > + * nodes but classifies each span as either a hole, where no nodes
> intersect,
> > > or
> > > + * a used, which is fully covered by nodes. Each iteration step toggles
> > > between
> > > + * hole and used until the entire range is covered. The returned spans
> > > always
> > > + * fully cover the requested range.
> > > + *
> > > + * The iterator is greedy, it always returns the largest hole or used
> possible,
> > > + * consolidating all consecutive nodes.
> > > + *
> > > + * Only is_hole, start_hole/used and last_hole/used are part of the
> external
> > > + * interface.
> >
> > slightly better readability if moving this sentence into the structure as
> > the break line
>
> Do you mean like this?
>
> @@ -37,13 +37,16 @@ interval_tree_iter_next(struct interval_tree_node
> *node,
> * The iterator is greedy, it always returns the largest hole or used possible,
> * consolidating all consecutive nodes.
> - *
> - * Only is_hole, start_hole/used and last_hole/used are part of the external
> - * interface.
> */
> struct interval_tree_span_iter {
> struct interval_tree_node *nodes[2];
> unsigned long first_index;
> unsigned long last_index;
> +
> + /*
> + * Only is_hole, start_hole/used and last_hole/used are part of the
> + * external interface.
> + */
/* Members below here are part of the external interface */
> union {
> unsigned long start_hole;
> unsigned long start_used;
>
> > > +void interval_tree_span_iter_advance(struct interval_tree_span_iter
> *iter,
> > > + struct rb_root_cached *itree,
> > > + unsigned long new_index)
> > > +{
> > > + if (iter->is_hole == -1)
> > > + return;
> > > +
> > > + iter->first_index = new_index;
> > > + if (new_index == iter->last_index) {
> > > + iter->is_hole = -1;
> > > + return;
> > > + }
> > > +
> > > + /* Rely on the union aliasing hole/used */
> > > + if (iter->start_hole <= new_index && new_index <= iter->last_hole) {
> >
> > "<=" to "<"
> >
> > > + iter->start_hole = new_index;
> > > + return;
> > > + }
>
> Hrm, I don't think so.. This is testing if new_index is valid for the
> current span. new_index == start_XXX is a valid index of the span and
> new_index == last_XX is also a valid index, so either of them should
> just update start_XX and do nothing else.
>
You are right.
