projects/linux·blob master · refs

230 lines · 4.9 KiB

1
2#include <linux/atomic.h>
3#include <linux/export.h>
4#include <linux/generic-radix-tree.h>
5#include <linux/gfp.h>
6#include <linux/kmemleak.h>
7
8/*
9 * Returns pointer to the specified byte @offset within @radix, or NULL if not
10 * allocated
11 */
12void *__genradix_ptr(struct __genradix *radix, size_t offset)
13{
14 return __genradix_ptr_inlined(radix, offset);
15}
16EXPORT_SYMBOL(__genradix_ptr);
17
18/*
19 * Returns pointer to the specified byte @offset within @radix, allocating it if
20 * necessary - newly allocated slots are always zeroed out:
21 */
22void *__genradix_ptr_alloc(struct __genradix *radix, size_t offset,
23 struct genradix_node **preallocated,
24 gfp_t gfp_mask)
25{
26 struct genradix_root *v = READ_ONCE(radix->root);
27 struct genradix_node *n, *new_node = NULL;
28 unsigned level;
29
30 if (preallocated)
31 swap(new_node, *preallocated);
32
33 /* Increase tree depth if necessary: */
34 while (1) {
35 struct genradix_root *r = v, *new_root;
36
37 n = genradix_root_to_node(r);
38 level = genradix_root_to_depth(r);
39
40 if (n && ilog2(offset) < genradix_depth_shift(level))
41 break;
42
43 if (!new_node) {
44 new_node = genradix_alloc_node(gfp_mask);
45 if (!new_node)
46 return NULL;
47 }
48
49 new_node->children[0] = n;
50 new_root = ((struct genradix_root *)
51 ((unsigned long) new_node | (n ? level + 1 : 0)));
52
53 if ((v = cmpxchg_release(&radix->root, r, new_root)) == r) {
54 v = new_root;
55 new_node = NULL;
56 } else {
57 new_node->children[0] = NULL;
58 }
59 }
60
61 while (level--) {
62 struct genradix_node **p =
63 &n->children[offset >> genradix_depth_shift(level)];
64 offset &= genradix_depth_size(level) - 1;
65
66 n = READ_ONCE(*p);
67 if (!n) {
68 if (!new_node) {
69 new_node = genradix_alloc_node(gfp_mask);
70 if (!new_node)
71 return NULL;
72 }
73
74 if (!(n = cmpxchg_release(p, NULL, new_node)))
75 swap(n, new_node);
76 }
77 }
78
79 if (new_node)
80 genradix_free_node(new_node);
81
82 return &n->data[offset];
83}
84EXPORT_SYMBOL(__genradix_ptr_alloc);
85
86void *__genradix_iter_peek(struct genradix_iter *iter,
87 struct __genradix *radix,
88 size_t objs_per_page)
89{
90 struct genradix_root *r;
91 struct genradix_node *n;
92 unsigned level, i;
93
94 if (iter->offset == SIZE_MAX)
95 return NULL;
96
97restart:
98 r = READ_ONCE(radix->root);
99 if (!r)
100 return NULL;
101
102 n = genradix_root_to_node(r);
103 level = genradix_root_to_depth(r);
104
105 if (ilog2(iter->offset) >= genradix_depth_shift(level))
106 return NULL;
107
108 while (level) {
109 level--;
110
111 i = (iter->offset >> genradix_depth_shift(level)) &
112 (GENRADIX_ARY - 1);
113
114 while (!n->children[i]) {
115 size_t objs_per_ptr = genradix_depth_size(level);
116
117 if (iter->offset + objs_per_ptr < iter->offset) {
118 iter->offset = SIZE_MAX;
119 iter->pos = SIZE_MAX;
120 return NULL;
121 }
122
123 i++;
124 iter->offset = round_down(iter->offset + objs_per_ptr,
125 objs_per_ptr);
126 iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) *
127 objs_per_page;
128 if (i == GENRADIX_ARY)
129 goto restart;
130 }
131
132 n = n->children[i];
133 }
134
135 return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
136}
137EXPORT_SYMBOL(__genradix_iter_peek);
138
139void *__genradix_iter_peek_prev(struct genradix_iter *iter,
140 struct __genradix *radix,
141 size_t objs_per_page,
142 size_t obj_size_plus_page_remainder)
143{
144 struct genradix_root *r;
145 struct genradix_node *n;
146 unsigned level, i;
147
148 if (iter->offset == SIZE_MAX)
149 return NULL;
150
151restart:
152 r = READ_ONCE(radix->root);
153 if (!r)
154 return NULL;
155
156 n = genradix_root_to_node(r);
157 level = genradix_root_to_depth(r);
158
159 if (ilog2(iter->offset) >= genradix_depth_shift(level)) {
160 iter->offset = genradix_depth_size(level);
161 iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
162
163 iter->offset -= obj_size_plus_page_remainder;
164 iter->pos--;
165 }
166
167 while (level) {
168 level--;
169
170 i = (iter->offset >> genradix_depth_shift(level)) &
171 (GENRADIX_ARY - 1);
172
173 while (!n->children[i]) {
174 size_t objs_per_ptr = genradix_depth_size(level);
175
176 iter->offset = round_down(iter->offset, objs_per_ptr);
177 iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
178
179 if (!iter->offset)
180 return NULL;
181
182 iter->offset -= obj_size_plus_page_remainder;
183 iter->pos--;
184
185 if (!i)
186 goto restart;
187 --i;
188 }
189
190 n = n->children[i];
191 }
192
193 return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
194}
195EXPORT_SYMBOL(__genradix_iter_peek_prev);
196
197static void genradix_free_recurse(struct genradix_node *n, unsigned level)
198{
199 if (level) {
200 unsigned i;
201
202 for (i = 0; i < GENRADIX_ARY; i++)
203 if (n->children[i])
204 genradix_free_recurse(n->children[i], level - 1);
205 }
206
207 genradix_free_node(n);
208}
209
210int __genradix_prealloc(struct __genradix *radix, size_t size,
211 gfp_t gfp_mask)
212{
213 size_t offset;
214
215 for (offset = 0; offset < size; offset += GENRADIX_NODE_SIZE)
216 if (!__genradix_ptr_alloc(radix, offset, NULL, gfp_mask))
217 return -ENOMEM;
218
219 return 0;
220}
221EXPORT_SYMBOL(__genradix_prealloc);
222
223void __genradix_free(struct __genradix *radix)
224{
225 struct genradix_root *r = xchg(&radix->root, NULL);
226
227 genradix_free_recurse(genradix_root_to_node(r),
228 genradix_root_to_depth(r));
229}
230EXPORT_SYMBOL(__genradix_free);