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1 | #ifndef _LINUX_GENERIC_RADIX_TREE_H |
2 | #define _LINUX_GENERIC_RADIX_TREE_H | |
3 | ||
4 | /** | |
590ba22b | 5 | * DOC: Generic radix trees/sparse arrays |
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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> | |
9492261f | 41 | #include <linux/limits.h> |
ba20ba2e | 42 | #include <linux/log2.h> |
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43 | #include <linux/math.h> |
44 | #include <linux/types.h> | |
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45 | |
46 | struct genradix_root; | |
47 | ||
48 | struct __genradix { | |
0a650e47 | 49 | struct genradix_root *root; |
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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(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_idx_to_offset(_radix, _idx) \ | |
121 | __idx_to_offset(_idx, __genradix_obj_size(_radix)) | |
122 | ||
123 | void *__genradix_ptr(struct __genradix *, size_t); | |
124 | ||
125 | /** | |
126 | * genradix_ptr - get a pointer to a genradix entry | |
127 | * @_radix: genradix to access | |
128 | * @_idx: index to fetch | |
129 | * | |
130 | * Returns a pointer to entry at @_idx, or NULL if that entry does not exist. | |
131 | */ | |
132 | #define genradix_ptr(_radix, _idx) \ | |
133 | (__genradix_cast(_radix) \ | |
134 | __genradix_ptr(&(_radix)->tree, \ | |
135 | __genradix_idx_to_offset(_radix, _idx))) | |
136 | ||
137 | void *__genradix_ptr_alloc(struct __genradix *, size_t, gfp_t); | |
138 | ||
139 | /** | |
140 | * genradix_ptr_alloc - get a pointer to a genradix entry, allocating it | |
141 | * if necessary | |
142 | * @_radix: genradix to access | |
143 | * @_idx: index to fetch | |
144 | * @_gfp: gfp mask | |
145 | * | |
146 | * Returns a pointer to entry at @_idx, or NULL on allocation failure | |
147 | */ | |
148 | #define genradix_ptr_alloc(_radix, _idx, _gfp) \ | |
149 | (__genradix_cast(_radix) \ | |
150 | __genradix_ptr_alloc(&(_radix)->tree, \ | |
151 | __genradix_idx_to_offset(_radix, _idx), \ | |
152 | _gfp)) | |
153 | ||
154 | struct genradix_iter { | |
155 | size_t offset; | |
156 | size_t pos; | |
157 | }; | |
158 | ||
159 | /** | |
160 | * genradix_iter_init - initialize a genradix_iter | |
161 | * @_radix: genradix that will be iterated over | |
162 | * @_idx: index to start iterating from | |
163 | */ | |
164 | #define genradix_iter_init(_radix, _idx) \ | |
165 | ((struct genradix_iter) { \ | |
166 | .pos = (_idx), \ | |
167 | .offset = __genradix_idx_to_offset((_radix), (_idx)),\ | |
168 | }) | |
169 | ||
170 | void *__genradix_iter_peek(struct genradix_iter *, struct __genradix *, size_t); | |
171 | ||
172 | /** | |
173 | * genradix_iter_peek - get first entry at or above iterator's current | |
174 | * position | |
175 | * @_iter: a genradix_iter | |
176 | * @_radix: genradix being iterated over | |
177 | * | |
178 | * If no more entries exist at or above @_iter's current position, returns NULL | |
179 | */ | |
180 | #define genradix_iter_peek(_iter, _radix) \ | |
181 | (__genradix_cast(_radix) \ | |
182 | __genradix_iter_peek(_iter, &(_radix)->tree, \ | |
183 | PAGE_SIZE / __genradix_obj_size(_radix))) | |
184 | ||
185 | static inline void __genradix_iter_advance(struct genradix_iter *iter, | |
186 | size_t obj_size) | |
187 | { | |
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188 | if (iter->offset + obj_size < iter->offset) { |
189 | iter->offset = SIZE_MAX; | |
190 | iter->pos = SIZE_MAX; | |
191 | return; | |
192 | } | |
193 | ||
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194 | iter->offset += obj_size; |
195 | ||
196 | if (!is_power_of_2(obj_size) && | |
197 | (iter->offset & (PAGE_SIZE - 1)) + obj_size > PAGE_SIZE) | |
198 | iter->offset = round_up(iter->offset, PAGE_SIZE); | |
199 | ||
200 | iter->pos++; | |
201 | } | |
202 | ||
203 | #define genradix_iter_advance(_iter, _radix) \ | |
204 | __genradix_iter_advance(_iter, __genradix_obj_size(_radix)) | |
205 | ||
206 | #define genradix_for_each_from(_radix, _iter, _p, _start) \ | |
207 | for (_iter = genradix_iter_init(_radix, _start); \ | |
208 | (_p = genradix_iter_peek(&_iter, _radix)) != NULL; \ | |
209 | genradix_iter_advance(&_iter, _radix)) | |
210 | ||
211 | /** | |
212 | * genradix_for_each - iterate over entry in a genradix | |
213 | * @_radix: genradix to iterate over | |
214 | * @_iter: a genradix_iter to track current position | |
215 | * @_p: pointer to genradix entry type | |
216 | * | |
217 | * On every iteration, @_p will point to the current entry, and @_iter.pos | |
218 | * will be the current entry's index. | |
219 | */ | |
220 | #define genradix_for_each(_radix, _iter, _p) \ | |
221 | genradix_for_each_from(_radix, _iter, _p, 0) | |
222 | ||
223 | int __genradix_prealloc(struct __genradix *, size_t, gfp_t); | |
224 | ||
225 | /** | |
226 | * genradix_prealloc - preallocate entries in a generic radix tree | |
227 | * @_radix: genradix to preallocate | |
228 | * @_nr: number of entries to preallocate | |
229 | * @_gfp: gfp mask | |
230 | * | |
231 | * Returns 0 on success, -ENOMEM on failure | |
232 | */ | |
233 | #define genradix_prealloc(_radix, _nr, _gfp) \ | |
234 | __genradix_prealloc(&(_radix)->tree, \ | |
235 | __genradix_idx_to_offset(_radix, _nr + 1),\ | |
236 | _gfp) | |
237 | ||
238 | ||
239 | #endif /* _LINUX_GENERIC_RADIX_TREE_H */ |