1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/interval_tree.h>
3#include <linux/interval_tree_generic.h>
4#include <linux/compiler.h>
5#include <linux/export.h>
6
7#define START(node) ((node)->start)
8#define LAST(node)  ((node)->last)
9
10INTERVAL_TREE_DEFINE(struct interval_tree_node, rb,
11		     unsigned long, __subtree_last,
12		     START, LAST,, interval_tree)
13
14EXPORT_SYMBOL_GPL(interval_tree_insert);
15EXPORT_SYMBOL_GPL(interval_tree_remove);
16EXPORT_SYMBOL_GPL(interval_tree_iter_first);
17EXPORT_SYMBOL_GPL(interval_tree_iter_next);
18
19#ifdef CONFIG_INTERVAL_TREE_SPAN_ITER
20/*
21 * Roll nodes[1] into nodes[0] by advancing nodes[1] to the end of a contiguous
22 * span of nodes. This makes nodes[0]->last the end of that contiguous used span
23 * indexes that started at the original nodes[1]->start. nodes[1] is now the
24 * first node starting the next used span. A hole span is between nodes[0]->last
25 * and nodes[1]->start. nodes[1] must be !NULL.
26 */
27static void
28interval_tree_span_iter_next_gap(struct interval_tree_span_iter *state)
29{
30	struct interval_tree_node *cur = state->nodes[1];
31
32	state->nodes[0] = cur;
33	do {
34		if (cur->last > state->nodes[0]->last)
35			state->nodes[0] = cur;
36		cur = interval_tree_iter_next(cur, state->first_index,
37					      state->last_index);
38	} while (cur && (state->nodes[0]->last >= cur->start ||
39			 state->nodes[0]->last + 1 == cur->start));
40	state->nodes[1] = cur;
41}
42
43void interval_tree_span_iter_first(struct interval_tree_span_iter *iter,
44				   struct rb_root_cached *itree,
45				   unsigned long first_index,
46				   unsigned long last_index)
47{
48	iter->first_index = first_index;
49	iter->last_index = last_index;
50	iter->nodes[0] = NULL;
51	iter->nodes[1] =
52		interval_tree_iter_first(itree, first_index, last_index);
53	if (!iter->nodes[1]) {
54		/* No nodes intersect the span, whole span is hole */
55		iter->start_hole = first_index;
56		iter->last_hole = last_index;
57		iter->is_hole = 1;
58		return;
59	}
60	if (iter->nodes[1]->start > first_index) {
61		/* Leading hole on first iteration */
62		iter->start_hole = first_index;
63		iter->last_hole = iter->nodes[1]->start - 1;
64		iter->is_hole = 1;
65		interval_tree_span_iter_next_gap(iter);
66		return;
67	}
68
69	/* Starting inside a used */
70	iter->start_used = first_index;
71	iter->is_hole = 0;
72	interval_tree_span_iter_next_gap(iter);
73	iter->last_used = iter->nodes[0]->last;
74	if (iter->last_used >= last_index) {
75		iter->last_used = last_index;
76		iter->nodes[0] = NULL;
77		iter->nodes[1] = NULL;
78	}
79}
80EXPORT_SYMBOL_GPL(interval_tree_span_iter_first);
81
82void interval_tree_span_iter_next(struct interval_tree_span_iter *iter)
83{
84	if (!iter->nodes[0] && !iter->nodes[1]) {
85		iter->is_hole = -1;
86		return;
87	}
88
89	if (iter->is_hole) {
90		iter->start_used = iter->last_hole + 1;
91		iter->last_used = iter->nodes[0]->last;
92		if (iter->last_used >= iter->last_index) {
93			iter->last_used = iter->last_index;
94			iter->nodes[0] = NULL;
95			iter->nodes[1] = NULL;
96		}
97		iter->is_hole = 0;
98		return;
99	}
100
101	if (!iter->nodes[1]) {
102		/* Trailing hole */
103		iter->start_hole = iter->nodes[0]->last + 1;
104		iter->last_hole = iter->last_index;
105		iter->nodes[0] = NULL;
106		iter->is_hole = 1;
107		return;
108	}
109
110	/* must have both nodes[0] and [1], interior hole */
111	iter->start_hole = iter->nodes[0]->last + 1;
112	iter->last_hole = iter->nodes[1]->start - 1;
113	iter->is_hole = 1;
114	interval_tree_span_iter_next_gap(iter);
115}
116EXPORT_SYMBOL_GPL(interval_tree_span_iter_next);
117
118/*
119 * Advance the iterator index to a specific position. The returned used/hole is
120 * updated to start at new_index. This is faster than calling
121 * interval_tree_span_iter_first() as it can avoid full searches in several
122 * cases where the iterator is already set.
123 */
124void interval_tree_span_iter_advance(struct interval_tree_span_iter *iter,
125				     struct rb_root_cached *itree,
126				     unsigned long new_index)
127{
128	if (iter->is_hole == -1)
129		return;
130
131	iter->first_index = new_index;
132	if (new_index > iter->last_index) {
133		iter->is_hole = -1;
134		return;
135	}
136
137	/* Rely on the union aliasing hole/used */
138	if (iter->start_hole <= new_index && new_index <= iter->last_hole) {
139		iter->start_hole = new_index;
140		return;
141	}
142	if (new_index == iter->last_hole + 1)
143		interval_tree_span_iter_next(iter);
144	else
145		interval_tree_span_iter_first(iter, itree, new_index,
146					      iter->last_index);
147}
148EXPORT_SYMBOL_GPL(interval_tree_span_iter_advance);
149#endif
150