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 #define GENRADIX_ARY (GENRADIX_NODE_SIZE / sizeof(struct genradix_node *))
9 #define GENRADIX_ARY_SHIFT ilog2(GENRADIX_ARY)
10
11 struct genradix_node {
12 union {
13 /* Interior node: */
14 struct genradix_node *children[GENRADIX_ARY];
15
16 /* Leaf: */
17 u8 data[GENRADIX_NODE_SIZE];
18 };
19 };
20
21 static inline int genradix_depth_shift(unsigned depth)
22 {
23 return GENRADIX_NODE_SHIFT + GENRADIX_ARY_SHIFT * depth;
24 }
25
26 /*
27 * Returns size (of data, in bytes) that a tree of a given depth holds:
28 */
29 static inline size_t genradix_depth_size(unsigned depth)
30 {
31 return 1UL << genradix_depth_shift(depth);
32 }
33
34 /* depth that's needed for a genradix that can address up to ULONG_MAX: */
35 #define GENRADIX_MAX_DEPTH \
36 DIV_ROUND_UP(BITS_PER_LONG - GENRADIX_NODE_SHIFT, GENRADIX_ARY_SHIFT)
37
38 #define GENRADIX_DEPTH_MASK \
39 ((unsigned long) (roundup_pow_of_two(GENRADIX_MAX_DEPTH + 1) - 1))
40
41 static inline unsigned genradix_root_to_depth(struct genradix_root *r)
42 {
43 return (unsigned long) r & GENRADIX_DEPTH_MASK;
44 }
45
46 static inline struct genradix_node *genradix_root_to_node(struct genradix_root *r)
47 {
48 return (void *) ((unsigned long) r & ~GENRADIX_DEPTH_MASK);
49 }
50
51 /*
52 * Returns pointer to the specified byte @offset within @radix, or NULL if not
53 * allocated
54 */
55 void *__genradix_ptr(struct __genradix *radix, size_t offset)
56 {
57 struct genradix_root *r = READ_ONCE(radix->root);
58 struct genradix_node *n = genradix_root_to_node(r);
59 unsigned level = genradix_root_to_depth(r);
60
61 if (ilog2(offset) >= genradix_depth_shift(level))
62 return NULL;
63
64 while (1) {
65 if (!n)
66 return NULL;
67 if (!level)
68 break;
69
70 level--;
71
72 n = n->children[offset >> genradix_depth_shift(level)];
73 offset &= genradix_depth_size(level) - 1;
74 }
75
76 return &n->data[offset];
77 }
78 EXPORT_SYMBOL(__genradix_ptr);
79
80 static inline struct genradix_node *genradix_alloc_node(gfp_t gfp_mask)
81 {
82 return kzalloc(GENRADIX_NODE_SIZE, gfp_mask);
83 }
84
85 static inline void genradix_free_node(struct genradix_node *node)
86 {
87 kfree(node);
88 }
89
90 /*
91 * Returns pointer to the specified byte @offset within @radix, allocating it if
92 * necessary - newly allocated slots are always zeroed out:
93 */
94 void *__genradix_ptr_alloc(struct __genradix *radix, size_t offset,
95 gfp_t gfp_mask)
96 {
97 struct genradix_root *v = READ_ONCE(radix->root);
98 struct genradix_node *n, *new_node = NULL;
99 unsigned level;
100
101 /* Increase tree depth if necessary: */
102 while (1) {
103 struct genradix_root *r = v, *new_root;
104
105 n = genradix_root_to_node(r);
106 level = genradix_root_to_depth(r);
107
108 if (n && ilog2(offset) < genradix_depth_shift(level))
109 break;
110
111 if (!new_node) {
112 new_node = genradix_alloc_node(gfp_mask);
113 if (!new_node)
114 return NULL;
115 }
116
117 new_node->children[0] = n;
118 new_root = ((struct genradix_root *)
119 ((unsigned long) new_node | (n ? level + 1 : 0)));
120
121 if ((v = cmpxchg_release(&radix->root, r, new_root)) == r) {
122 v = new_root;
123 new_node = NULL;
124 } else {
125 new_node->children[0] = NULL;
126 }
127 }
128
129 while (level--) {
130 struct genradix_node **p =
131 &n->children[offset >> genradix_depth_shift(level)];
132 offset &= genradix_depth_size(level) - 1;
133
134 n = READ_ONCE(*p);
135 if (!n) {
136 if (!new_node) {
137 new_node = genradix_alloc_node(gfp_mask);
138 if (!new_node)
139 return NULL;
140 }
141
142 if (!(n = cmpxchg_release(p, NULL, new_node)))
143 swap(n, new_node);
144 }
145 }
146
147 if (new_node)
148 genradix_free_node(new_node);
149
150 return &n->data[offset];
151 }
152 EXPORT_SYMBOL(__genradix_ptr_alloc);
153
154 void *__genradix_iter_peek(struct genradix_iter *iter,
155 struct __genradix *radix,
156 size_t objs_per_page)
157 {
158 struct genradix_root *r;
159 struct genradix_node *n;
160 unsigned level, i;
161
162 if (iter->offset == SIZE_MAX)
163 return NULL;
164
165 restart:
166 r = READ_ONCE(radix->root);
167 if (!r)
168 return NULL;
169
170 n = genradix_root_to_node(r);
171 level = genradix_root_to_depth(r);
172
173 if (ilog2(iter->offset) >= genradix_depth_shift(level))
174 return NULL;
175
176 while (level) {
177 level--;
178
179 i = (iter->offset >> genradix_depth_shift(level)) &
180 (GENRADIX_ARY - 1);
181
182 while (!n->children[i]) {
183 size_t objs_per_ptr = genradix_depth_size(level);
184
185 if (iter->offset + objs_per_ptr < iter->offset) {
186 iter->offset = SIZE_MAX;
187 iter->pos = SIZE_MAX;
188 return NULL;
189 }
190
191 i++;
192 iter->offset = round_down(iter->offset + objs_per_ptr,
193 objs_per_ptr);
194 iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) *
195 objs_per_page;
196 if (i == GENRADIX_ARY)
197 goto restart;
198 }
199
200 n = n->children[i];
201 }
202
203 return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
204 }
205 EXPORT_SYMBOL(__genradix_iter_peek);
206
207 void *__genradix_iter_peek_prev(struct genradix_iter *iter,
208 struct __genradix *radix,
209 size_t objs_per_page,
210 size_t obj_size_plus_page_remainder)
211 {
212 struct genradix_root *r;
213 struct genradix_node *n;
214 unsigned level, i;
215
216 if (iter->offset == SIZE_MAX)
217 return NULL;
218
219 restart:
220 r = READ_ONCE(radix->root);
221 if (!r)
222 return NULL;
223
224 n = genradix_root_to_node(r);
225 level = genradix_root_to_depth(r);
226
227 if (ilog2(iter->offset) >= genradix_depth_shift(level)) {
228 iter->offset = genradix_depth_size(level);
229 iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
230
231 iter->offset -= obj_size_plus_page_remainder;
232 iter->pos--;
233 }
234
235 while (level) {
236 level--;
237
238 i = (iter->offset >> genradix_depth_shift(level)) &
239 (GENRADIX_ARY - 1);
240
241 while (!n->children[i]) {
242 size_t objs_per_ptr = genradix_depth_size(level);
243
244 iter->offset = round_down(iter->offset, objs_per_ptr);
245 iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
246
247 if (!iter->offset)
248 return NULL;
249
250 iter->offset -= obj_size_plus_page_remainder;
251 iter->pos--;
252
253 if (!i)
254 goto restart;
255 --i;
256 }
257
258 n = n->children[i];
259 }
260
261 return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
262 }
263 EXPORT_SYMBOL(__genradix_iter_peek_prev);
264
265 static void genradix_free_recurse(struct genradix_node *n, unsigned level)
266 {
267 if (level) {
268 unsigned i;
269
270 for (i = 0; i < GENRADIX_ARY; i++)
271 if (n->children[i])
272 genradix_free_recurse(n->children[i], level - 1);
273 }
274
275 genradix_free_node(n);
276 }
277
278 int __genradix_prealloc(struct __genradix *radix, size_t size,
279 gfp_t gfp_mask)
280 {
281 size_t offset;
282
283 for (offset = 0; offset < size; offset += GENRADIX_NODE_SIZE)
284 if (!__genradix_ptr_alloc(radix, offset, gfp_mask))
285 return -ENOMEM;
286
287 return 0;
288 }
289 EXPORT_SYMBOL(__genradix_prealloc);
290
291 void __genradix_free(struct __genradix *radix)
292 {
293 struct genradix_root *r = xchg(&radix->root, NULL);
294
295 genradix_free_recurse(genradix_root_to_node(r),
296 genradix_root_to_depth(r));
297 }
298 EXPORT_SYMBOL(__genradix_free);
299
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