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
genradix_depth_shift(unsigned depth)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 */
genradix_depth_size(unsigned depth)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
genradix_root_to_depth(struct genradix_root * r)41 static inline unsigned genradix_root_to_depth(struct genradix_root *r)
42 {
43 return (unsigned long) r & GENRADIX_DEPTH_MASK;
44 }
45
genradix_root_to_node(struct genradix_root * r)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 */
__genradix_ptr(struct __genradix * radix,size_t offset)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
genradix_alloc_node(gfp_t gfp_mask)80 static inline struct genradix_node *genradix_alloc_node(gfp_t gfp_mask)
81 {
82 return kzalloc(GENRADIX_NODE_SIZE, gfp_mask);
83 }
84
genradix_free_node(struct genradix_node * node)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 */
__genradix_ptr_alloc(struct __genradix * radix,size_t offset,gfp_t gfp_mask)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 }
125 }
126
127 while (level--) {
128 struct genradix_node **p =
129 &n->children[offset >> genradix_depth_shift(level)];
130 offset &= genradix_depth_size(level) - 1;
131
132 n = READ_ONCE(*p);
133 if (!n) {
134 if (!new_node) {
135 new_node = genradix_alloc_node(gfp_mask);
136 if (!new_node)
137 return NULL;
138 }
139
140 if (!(n = cmpxchg_release(p, NULL, new_node)))
141 swap(n, new_node);
142 }
143 }
144
145 if (new_node)
146 genradix_free_node(new_node);
147
148 return &n->data[offset];
149 }
150 EXPORT_SYMBOL(__genradix_ptr_alloc);
151
__genradix_iter_peek(struct genradix_iter * iter,struct __genradix * radix,size_t objs_per_page)152 void *__genradix_iter_peek(struct genradix_iter *iter,
153 struct __genradix *radix,
154 size_t objs_per_page)
155 {
156 struct genradix_root *r;
157 struct genradix_node *n;
158 unsigned level, i;
159
160 if (iter->offset == SIZE_MAX)
161 return NULL;
162
163 restart:
164 r = READ_ONCE(radix->root);
165 if (!r)
166 return NULL;
167
168 n = genradix_root_to_node(r);
169 level = genradix_root_to_depth(r);
170
171 if (ilog2(iter->offset) >= genradix_depth_shift(level))
172 return NULL;
173
174 while (level) {
175 level--;
176
177 i = (iter->offset >> genradix_depth_shift(level)) &
178 (GENRADIX_ARY - 1);
179
180 while (!n->children[i]) {
181 size_t objs_per_ptr = genradix_depth_size(level);
182
183 if (iter->offset + objs_per_ptr < iter->offset) {
184 iter->offset = SIZE_MAX;
185 iter->pos = SIZE_MAX;
186 return NULL;
187 }
188
189 i++;
190 iter->offset = round_down(iter->offset + objs_per_ptr,
191 objs_per_ptr);
192 iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) *
193 objs_per_page;
194 if (i == GENRADIX_ARY)
195 goto restart;
196 }
197
198 n = n->children[i];
199 }
200
201 return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
202 }
203 EXPORT_SYMBOL(__genradix_iter_peek);
204
__genradix_iter_peek_prev(struct genradix_iter * iter,struct __genradix * radix,size_t objs_per_page,size_t obj_size_plus_page_remainder)205 void *__genradix_iter_peek_prev(struct genradix_iter *iter,
206 struct __genradix *radix,
207 size_t objs_per_page,
208 size_t obj_size_plus_page_remainder)
209 {
210 struct genradix_root *r;
211 struct genradix_node *n;
212 unsigned level, i;
213
214 if (iter->offset == SIZE_MAX)
215 return NULL;
216
217 restart:
218 r = READ_ONCE(radix->root);
219 if (!r)
220 return NULL;
221
222 n = genradix_root_to_node(r);
223 level = genradix_root_to_depth(r);
224
225 if (ilog2(iter->offset) >= genradix_depth_shift(level)) {
226 iter->offset = genradix_depth_size(level);
227 iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
228
229 iter->offset -= obj_size_plus_page_remainder;
230 iter->pos--;
231 }
232
233 while (level) {
234 level--;
235
236 i = (iter->offset >> genradix_depth_shift(level)) &
237 (GENRADIX_ARY - 1);
238
239 while (!n->children[i]) {
240 size_t objs_per_ptr = genradix_depth_size(level);
241
242 iter->offset = round_down(iter->offset, objs_per_ptr);
243 iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
244
245 if (!iter->offset)
246 return NULL;
247
248 iter->offset -= obj_size_plus_page_remainder;
249 iter->pos--;
250
251 if (!i)
252 goto restart;
253 --i;
254 }
255
256 n = n->children[i];
257 }
258
259 return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
260 }
261 EXPORT_SYMBOL(__genradix_iter_peek_prev);
262
genradix_free_recurse(struct genradix_node * n,unsigned level)263 static void genradix_free_recurse(struct genradix_node *n, unsigned level)
264 {
265 if (level) {
266 unsigned i;
267
268 for (i = 0; i < GENRADIX_ARY; i++)
269 if (n->children[i])
270 genradix_free_recurse(n->children[i], level - 1);
271 }
272
273 genradix_free_node(n);
274 }
275
__genradix_prealloc(struct __genradix * radix,size_t size,gfp_t gfp_mask)276 int __genradix_prealloc(struct __genradix *radix, size_t size,
277 gfp_t gfp_mask)
278 {
279 size_t offset;
280
281 for (offset = 0; offset < size; offset += GENRADIX_NODE_SIZE)
282 if (!__genradix_ptr_alloc(radix, offset, gfp_mask))
283 return -ENOMEM;
284
285 return 0;
286 }
287 EXPORT_SYMBOL(__genradix_prealloc);
288
__genradix_free(struct __genradix * radix)289 void __genradix_free(struct __genradix *radix)
290 {
291 struct genradix_root *r = xchg(&radix->root, NULL);
292
293 genradix_free_recurse(genradix_root_to_node(r),
294 genradix_root_to_depth(r));
295 }
296 EXPORT_SYMBOL(__genradix_free);
297