1 | #ifndef _LINUX_GENERIC_RADIX_TREE_H |
2 | #define _LINUX_GENERIC_RADIX_TREE_H |
3 | |
4 | /** |
5 | * DOC: Generic radix trees/sparse arrays |
6 | * |
7 | * Very simple and minimalistic, supporting arbitrary size entries up to |
8 | * PAGE_SIZE. |
9 | * |
10 | * A genradix is defined with the type it will store, like so: |
11 | * |
12 | * static GENRADIX(struct foo) foo_genradix; |
13 | * |
14 | * The main operations are: |
15 | * |
16 | * - genradix_init(radix) - initialize an empty genradix |
17 | * |
18 | * - genradix_free(radix) - free all memory owned by the genradix and |
19 | * reinitialize it |
20 | * |
21 | * - genradix_ptr(radix, idx) - gets a pointer to the entry at idx, returning |
22 | * NULL if that entry does not exist |
23 | * |
24 | * - genradix_ptr_alloc(radix, idx, gfp) - gets a pointer to an entry, |
25 | * allocating it if necessary |
26 | * |
27 | * - genradix_for_each(radix, iter, p) - iterate over each entry in a genradix |
28 | * |
29 | * The radix tree allocates one page of entries at a time, so entries may exist |
30 | * that were never explicitly allocated - they will be initialized to all |
31 | * zeroes. |
32 | * |
33 | * Internally, a genradix is just a radix tree of pages, and indexing works in |
34 | * terms of byte offsets. The wrappers in this header file use sizeof on the |
35 | * type the radix contains to calculate a byte offset from the index - see |
36 | * __idx_to_offset. |
37 | */ |
38 | |
39 | #include <asm/page.h> |
40 | #include <linux/bug.h> |
41 | #include <linux/limits.h> |
42 | #include <linux/log2.h> |
43 | #include <linux/math.h> |
44 | #include <linux/types.h> |
45 | |
46 | struct genradix_root; |
47 | |
48 | struct __genradix { |
49 | struct genradix_root *root; |
50 | }; |
51 | |
52 | /* |
53 | * NOTE: currently, sizeof(_type) must not be larger than PAGE_SIZE: |
54 | */ |
55 | |
56 | #define __GENRADIX_INITIALIZER \ |
57 | { \ |
58 | .tree = { \ |
59 | .root = NULL, \ |
60 | } \ |
61 | } |
62 | |
63 | /* |
64 | * We use a 0 size array to stash the type we're storing without taking any |
65 | * space at runtime - then the various accessor macros can use typeof() to get |
66 | * to it for casts/sizeof - we also force the alignment so that storing a type |
67 | * with a ridiculous alignment doesn't blow up the alignment or size of the |
68 | * genradix. |
69 | */ |
70 | |
71 | #define GENRADIX(_type) \ |
72 | struct { \ |
73 | struct __genradix tree; \ |
74 | _type type[0] __aligned(1); \ |
75 | } |
76 | |
77 | #define DEFINE_GENRADIX(_name, _type) \ |
78 | GENRADIX(_type) _name = __GENRADIX_INITIALIZER |
79 | |
80 | /** |
81 | * genradix_init - initialize a genradix |
82 | * @_radix: genradix to initialize |
83 | * |
84 | * Does not fail |
85 | */ |
86 | #define genradix_init(_radix) \ |
87 | do { \ |
88 | *(_radix) = (typeof(*_radix)) __GENRADIX_INITIALIZER; \ |
89 | } while (0) |
90 | |
91 | void __genradix_free(struct __genradix *); |
92 | |
93 | /** |
94 | * genradix_free: free all memory owned by a genradix |
95 | * @_radix: the genradix to free |
96 | * |
97 | * After freeing, @_radix will be reinitialized and empty |
98 | */ |
99 | #define genradix_free(_radix) __genradix_free(&(_radix)->tree) |
100 | |
101 | static inline size_t __idx_to_offset(size_t idx, size_t obj_size) |
102 | { |
103 | if (__builtin_constant_p(obj_size)) |
104 | BUILD_BUG_ON(obj_size > PAGE_SIZE); |
105 | else |
106 | BUG_ON(obj_size > PAGE_SIZE); |
107 | |
108 | if (!is_power_of_2(n: obj_size)) { |
109 | size_t objs_per_page = PAGE_SIZE / obj_size; |
110 | |
111 | return (idx / objs_per_page) * PAGE_SIZE + |
112 | (idx % objs_per_page) * obj_size; |
113 | } else { |
114 | return idx * obj_size; |
115 | } |
116 | } |
117 | |
118 | #define __genradix_cast(_radix) (typeof((_radix)->type[0]) *) |
119 | #define __genradix_obj_size(_radix) sizeof((_radix)->type[0]) |
120 | #define __genradix_objs_per_page(_radix) \ |
121 | (PAGE_SIZE / sizeof((_radix)->type[0])) |
122 | #define __genradix_page_remainder(_radix) \ |
123 | (PAGE_SIZE % sizeof((_radix)->type[0])) |
124 | |
125 | #define __genradix_idx_to_offset(_radix, _idx) \ |
126 | __idx_to_offset(_idx, __genradix_obj_size(_radix)) |
127 | |
128 | void *__genradix_ptr(struct __genradix *, size_t); |
129 | |
130 | /** |
131 | * genradix_ptr - get a pointer to a genradix entry |
132 | * @_radix: genradix to access |
133 | * @_idx: index to fetch |
134 | * |
135 | * Returns a pointer to entry at @_idx, or NULL if that entry does not exist. |
136 | */ |
137 | #define genradix_ptr(_radix, _idx) \ |
138 | (__genradix_cast(_radix) \ |
139 | __genradix_ptr(&(_radix)->tree, \ |
140 | __genradix_idx_to_offset(_radix, _idx))) |
141 | |
142 | void *__genradix_ptr_alloc(struct __genradix *, size_t, gfp_t); |
143 | |
144 | /** |
145 | * genradix_ptr_alloc - get a pointer to a genradix entry, allocating it |
146 | * if necessary |
147 | * @_radix: genradix to access |
148 | * @_idx: index to fetch |
149 | * @_gfp: gfp mask |
150 | * |
151 | * Returns a pointer to entry at @_idx, or NULL on allocation failure |
152 | */ |
153 | #define genradix_ptr_alloc(_radix, _idx, _gfp) \ |
154 | (__genradix_cast(_radix) \ |
155 | __genradix_ptr_alloc(&(_radix)->tree, \ |
156 | __genradix_idx_to_offset(_radix, _idx), \ |
157 | _gfp)) |
158 | |
159 | struct genradix_iter { |
160 | size_t offset; |
161 | size_t pos; |
162 | }; |
163 | |
164 | /** |
165 | * genradix_iter_init - initialize a genradix_iter |
166 | * @_radix: genradix that will be iterated over |
167 | * @_idx: index to start iterating from |
168 | */ |
169 | #define genradix_iter_init(_radix, _idx) \ |
170 | ((struct genradix_iter) { \ |
171 | .pos = (_idx), \ |
172 | .offset = __genradix_idx_to_offset((_radix), (_idx)),\ |
173 | }) |
174 | |
175 | void *__genradix_iter_peek(struct genradix_iter *, struct __genradix *, size_t); |
176 | |
177 | /** |
178 | * genradix_iter_peek - get first entry at or above iterator's current |
179 | * position |
180 | * @_iter: a genradix_iter |
181 | * @_radix: genradix being iterated over |
182 | * |
183 | * If no more entries exist at or above @_iter's current position, returns NULL |
184 | */ |
185 | #define genradix_iter_peek(_iter, _radix) \ |
186 | (__genradix_cast(_radix) \ |
187 | __genradix_iter_peek(_iter, &(_radix)->tree, \ |
188 | __genradix_objs_per_page(_radix))) |
189 | |
190 | void *__genradix_iter_peek_prev(struct genradix_iter *, struct __genradix *, |
191 | size_t, size_t); |
192 | |
193 | /** |
194 | * genradix_iter_peek_prev - get first entry at or below iterator's current |
195 | * position |
196 | * @_iter: a genradix_iter |
197 | * @_radix: genradix being iterated over |
198 | * |
199 | * If no more entries exist at or below @_iter's current position, returns NULL |
200 | */ |
201 | #define genradix_iter_peek_prev(_iter, _radix) \ |
202 | (__genradix_cast(_radix) \ |
203 | __genradix_iter_peek_prev(_iter, &(_radix)->tree, \ |
204 | __genradix_objs_per_page(_radix), \ |
205 | __genradix_obj_size(_radix) + \ |
206 | __genradix_page_remainder(_radix))) |
207 | |
208 | static inline void __genradix_iter_advance(struct genradix_iter *iter, |
209 | size_t obj_size) |
210 | { |
211 | if (iter->offset + obj_size < iter->offset) { |
212 | iter->offset = SIZE_MAX; |
213 | iter->pos = SIZE_MAX; |
214 | return; |
215 | } |
216 | |
217 | iter->offset += obj_size; |
218 | |
219 | if (!is_power_of_2(n: obj_size) && |
220 | (iter->offset & (PAGE_SIZE - 1)) + obj_size > PAGE_SIZE) |
221 | iter->offset = round_up(iter->offset, PAGE_SIZE); |
222 | |
223 | iter->pos++; |
224 | } |
225 | |
226 | #define genradix_iter_advance(_iter, _radix) \ |
227 | __genradix_iter_advance(_iter, __genradix_obj_size(_radix)) |
228 | |
229 | static inline void __genradix_iter_rewind(struct genradix_iter *iter, |
230 | size_t obj_size) |
231 | { |
232 | if (iter->offset == 0 || |
233 | iter->offset == SIZE_MAX) { |
234 | iter->offset = SIZE_MAX; |
235 | return; |
236 | } |
237 | |
238 | if ((iter->offset & (PAGE_SIZE - 1)) == 0) |
239 | iter->offset -= PAGE_SIZE % obj_size; |
240 | |
241 | iter->offset -= obj_size; |
242 | iter->pos--; |
243 | } |
244 | |
245 | #define genradix_iter_rewind(_iter, _radix) \ |
246 | __genradix_iter_rewind(_iter, __genradix_obj_size(_radix)) |
247 | |
248 | #define genradix_for_each_from(_radix, _iter, _p, _start) \ |
249 | for (_iter = genradix_iter_init(_radix, _start); \ |
250 | (_p = genradix_iter_peek(&_iter, _radix)) != NULL; \ |
251 | genradix_iter_advance(&_iter, _radix)) |
252 | |
253 | /** |
254 | * genradix_for_each - iterate over entry in a genradix |
255 | * @_radix: genradix to iterate over |
256 | * @_iter: a genradix_iter to track current position |
257 | * @_p: pointer to genradix entry type |
258 | * |
259 | * On every iteration, @_p will point to the current entry, and @_iter.pos |
260 | * will be the current entry's index. |
261 | */ |
262 | #define genradix_for_each(_radix, _iter, _p) \ |
263 | genradix_for_each_from(_radix, _iter, _p, 0) |
264 | |
265 | #define genradix_last_pos(_radix) \ |
266 | (SIZE_MAX / PAGE_SIZE * __genradix_objs_per_page(_radix) - 1) |
267 | |
268 | /** |
269 | * genradix_for_each_reverse - iterate over entry in a genradix, reverse order |
270 | * @_radix: genradix to iterate over |
271 | * @_iter: a genradix_iter to track current position |
272 | * @_p: pointer to genradix entry type |
273 | * |
274 | * On every iteration, @_p will point to the current entry, and @_iter.pos |
275 | * will be the current entry's index. |
276 | */ |
277 | #define genradix_for_each_reverse(_radix, _iter, _p) \ |
278 | for (_iter = genradix_iter_init(_radix, genradix_last_pos(_radix));\ |
279 | (_p = genradix_iter_peek_prev(&_iter, _radix)) != NULL;\ |
280 | genradix_iter_rewind(&_iter, _radix)) |
281 | |
282 | int __genradix_prealloc(struct __genradix *, size_t, gfp_t); |
283 | |
284 | /** |
285 | * genradix_prealloc - preallocate entries in a generic radix tree |
286 | * @_radix: genradix to preallocate |
287 | * @_nr: number of entries to preallocate |
288 | * @_gfp: gfp mask |
289 | * |
290 | * Returns 0 on success, -ENOMEM on failure |
291 | */ |
292 | #define genradix_prealloc(_radix, _nr, _gfp) \ |
293 | __genradix_prealloc(&(_radix)->tree, \ |
294 | __genradix_idx_to_offset(_radix, _nr + 1),\ |
295 | _gfp) |
296 | |
297 | |
298 | #endif /* _LINUX_GENERIC_RADIX_TREE_H */ |
299 | |