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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 |
ba20ba2e KO |
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/kernel.h> | |
42 | #include <linux/log2.h> | |
43 | ||
44 | struct genradix_root; | |
45 | ||
46 | struct __genradix { | |
47 | struct genradix_root __rcu *root; | |
48 | }; | |
49 | ||
50 | /* | |
51 | * NOTE: currently, sizeof(_type) must not be larger than PAGE_SIZE: | |
52 | */ | |
53 | ||
54 | #define __GENRADIX_INITIALIZER \ | |
55 | { \ | |
56 | .tree = { \ | |
57 | .root = NULL, \ | |
58 | } \ | |
59 | } | |
60 | ||
61 | /* | |
62 | * We use a 0 size array to stash the type we're storing without taking any | |
63 | * space at runtime - then the various accessor macros can use typeof() to get | |
64 | * to it for casts/sizeof - we also force the alignment so that storing a type | |
65 | * with a ridiculous alignment doesn't blow up the alignment or size of the | |
66 | * genradix. | |
67 | */ | |
68 | ||
69 | #define GENRADIX(_type) \ | |
70 | struct { \ | |
71 | struct __genradix tree; \ | |
72 | _type type[0] __aligned(1); \ | |
73 | } | |
74 | ||
75 | #define DEFINE_GENRADIX(_name, _type) \ | |
76 | GENRADIX(_type) _name = __GENRADIX_INITIALIZER | |
77 | ||
78 | /** | |
79 | * genradix_init - initialize a genradix | |
80 | * @_radix: genradix to initialize | |
81 | * | |
82 | * Does not fail | |
83 | */ | |
84 | #define genradix_init(_radix) \ | |
85 | do { \ | |
86 | *(_radix) = (typeof(*_radix)) __GENRADIX_INITIALIZER; \ | |
87 | } while (0) | |
88 | ||
89 | void __genradix_free(struct __genradix *); | |
90 | ||
91 | /** | |
92 | * genradix_free: free all memory owned by a genradix | |
93 | * @_radix: the genradix to free | |
94 | * | |
95 | * After freeing, @_radix will be reinitialized and empty | |
96 | */ | |
97 | #define genradix_free(_radix) __genradix_free(&(_radix)->tree) | |
98 | ||
99 | static inline size_t __idx_to_offset(size_t idx, size_t obj_size) | |
100 | { | |
101 | if (__builtin_constant_p(obj_size)) | |
102 | BUILD_BUG_ON(obj_size > PAGE_SIZE); | |
103 | else | |
104 | BUG_ON(obj_size > PAGE_SIZE); | |
105 | ||
106 | if (!is_power_of_2(obj_size)) { | |
107 | size_t objs_per_page = PAGE_SIZE / obj_size; | |
108 | ||
109 | return (idx / objs_per_page) * PAGE_SIZE + | |
110 | (idx % objs_per_page) * obj_size; | |
111 | } else { | |
112 | return idx * obj_size; | |
113 | } | |
114 | } | |
115 | ||
116 | #define __genradix_cast(_radix) (typeof((_radix)->type[0]) *) | |
117 | #define __genradix_obj_size(_radix) sizeof((_radix)->type[0]) | |
118 | #define __genradix_idx_to_offset(_radix, _idx) \ | |
119 | __idx_to_offset(_idx, __genradix_obj_size(_radix)) | |
120 | ||
121 | void *__genradix_ptr(struct __genradix *, size_t); | |
122 | ||
123 | /** | |
124 | * genradix_ptr - get a pointer to a genradix entry | |
125 | * @_radix: genradix to access | |
126 | * @_idx: index to fetch | |
127 | * | |
128 | * Returns a pointer to entry at @_idx, or NULL if that entry does not exist. | |
129 | */ | |
130 | #define genradix_ptr(_radix, _idx) \ | |
131 | (__genradix_cast(_radix) \ | |
132 | __genradix_ptr(&(_radix)->tree, \ | |
133 | __genradix_idx_to_offset(_radix, _idx))) | |
134 | ||
135 | void *__genradix_ptr_alloc(struct __genradix *, size_t, gfp_t); | |
136 | ||
137 | /** | |
138 | * genradix_ptr_alloc - get a pointer to a genradix entry, allocating it | |
139 | * if necessary | |
140 | * @_radix: genradix to access | |
141 | * @_idx: index to fetch | |
142 | * @_gfp: gfp mask | |
143 | * | |
144 | * Returns a pointer to entry at @_idx, or NULL on allocation failure | |
145 | */ | |
146 | #define genradix_ptr_alloc(_radix, _idx, _gfp) \ | |
147 | (__genradix_cast(_radix) \ | |
148 | __genradix_ptr_alloc(&(_radix)->tree, \ | |
149 | __genradix_idx_to_offset(_radix, _idx), \ | |
150 | _gfp)) | |
151 | ||
152 | struct genradix_iter { | |
153 | size_t offset; | |
154 | size_t pos; | |
155 | }; | |
156 | ||
157 | /** | |
158 | * genradix_iter_init - initialize a genradix_iter | |
159 | * @_radix: genradix that will be iterated over | |
160 | * @_idx: index to start iterating from | |
161 | */ | |
162 | #define genradix_iter_init(_radix, _idx) \ | |
163 | ((struct genradix_iter) { \ | |
164 | .pos = (_idx), \ | |
165 | .offset = __genradix_idx_to_offset((_radix), (_idx)),\ | |
166 | }) | |
167 | ||
168 | void *__genradix_iter_peek(struct genradix_iter *, struct __genradix *, size_t); | |
169 | ||
170 | /** | |
171 | * genradix_iter_peek - get first entry at or above iterator's current | |
172 | * position | |
173 | * @_iter: a genradix_iter | |
174 | * @_radix: genradix being iterated over | |
175 | * | |
176 | * If no more entries exist at or above @_iter's current position, returns NULL | |
177 | */ | |
178 | #define genradix_iter_peek(_iter, _radix) \ | |
179 | (__genradix_cast(_radix) \ | |
180 | __genradix_iter_peek(_iter, &(_radix)->tree, \ | |
181 | PAGE_SIZE / __genradix_obj_size(_radix))) | |
182 | ||
183 | static inline void __genradix_iter_advance(struct genradix_iter *iter, | |
184 | size_t obj_size) | |
185 | { | |
186 | iter->offset += obj_size; | |
187 | ||
188 | if (!is_power_of_2(obj_size) && | |
189 | (iter->offset & (PAGE_SIZE - 1)) + obj_size > PAGE_SIZE) | |
190 | iter->offset = round_up(iter->offset, PAGE_SIZE); | |
191 | ||
192 | iter->pos++; | |
193 | } | |
194 | ||
195 | #define genradix_iter_advance(_iter, _radix) \ | |
196 | __genradix_iter_advance(_iter, __genradix_obj_size(_radix)) | |
197 | ||
198 | #define genradix_for_each_from(_radix, _iter, _p, _start) \ | |
199 | for (_iter = genradix_iter_init(_radix, _start); \ | |
200 | (_p = genradix_iter_peek(&_iter, _radix)) != NULL; \ | |
201 | genradix_iter_advance(&_iter, _radix)) | |
202 | ||
203 | /** | |
204 | * genradix_for_each - iterate over entry in a genradix | |
205 | * @_radix: genradix to iterate over | |
206 | * @_iter: a genradix_iter to track current position | |
207 | * @_p: pointer to genradix entry type | |
208 | * | |
209 | * On every iteration, @_p will point to the current entry, and @_iter.pos | |
210 | * will be the current entry's index. | |
211 | */ | |
212 | #define genradix_for_each(_radix, _iter, _p) \ | |
213 | genradix_for_each_from(_radix, _iter, _p, 0) | |
214 | ||
215 | int __genradix_prealloc(struct __genradix *, size_t, gfp_t); | |
216 | ||
217 | /** | |
218 | * genradix_prealloc - preallocate entries in a generic radix tree | |
219 | * @_radix: genradix to preallocate | |
220 | * @_nr: number of entries to preallocate | |
221 | * @_gfp: gfp mask | |
222 | * | |
223 | * Returns 0 on success, -ENOMEM on failure | |
224 | */ | |
225 | #define genradix_prealloc(_radix, _nr, _gfp) \ | |
226 | __genradix_prealloc(&(_radix)->tree, \ | |
227 | __genradix_idx_to_offset(_radix, _nr + 1),\ | |
228 | _gfp) | |
229 | ||
230 | ||
231 | #endif /* _LINUX_GENERIC_RADIX_TREE_H */ |