projects/linux·blob v6.3-rc2 · refs

149 lines · 4.2 KiB

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