1 #ifndef _LINUX_GENERIC_RADIX_TREE_H
2 #define _LINUX_GENERIC_RADIX_TREE_H
5 * DOC: Generic radix trees/sparse arrays
7 * Very simple and minimalistic, supporting arbitrary size entries up to
10 * A genradix is defined with the type it will store, like so:
12 * static GENRADIX(struct foo) foo_genradix;
14 * The main operations are:
16 * - genradix_init(radix) - initialize an empty genradix
18 * - genradix_free(radix) - free all memory owned by the genradix and
21 * - genradix_ptr(radix, idx) - gets a pointer to the entry at idx, returning
22 * NULL if that entry does not exist
24 * - genradix_ptr_alloc(radix, idx, gfp) - gets a pointer to an entry,
25 * allocating it if necessary
27 * - genradix_for_each(radix, iter, p) - iterate over each entry in a genradix
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
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
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>
49 struct genradix_root *root;
53 * NOTE: currently, sizeof(_type) must not be larger than PAGE_SIZE:
56 #define __GENRADIX_INITIALIZER \
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
71 #define GENRADIX(_type) \
73 struct __genradix tree; \
74 _type type[0] __aligned(1); \
77 #define DEFINE_GENRADIX(_name, _type) \
78 GENRADIX(_type) _name = __GENRADIX_INITIALIZER
81 * genradix_init - initialize a genradix
82 * @_radix: genradix to initialize
86 #define genradix_init(_radix) \
88 *(_radix) = (typeof(*_radix)) __GENRADIX_INITIALIZER; \
91 void __genradix_free(struct __genradix *);
94 * genradix_free: free all memory owned by a genradix
95 * @_radix: the genradix to free
97 * After freeing, @_radix will be reinitialized and empty
99 #define genradix_free(_radix) __genradix_free(&(_radix)->tree)
101 static inline size_t __idx_to_offset(size_t idx, size_t obj_size)
103 if (__builtin_constant_p(obj_size))
104 BUILD_BUG_ON(obj_size > PAGE_SIZE);
106 BUG_ON(obj_size > PAGE_SIZE);
108 if (!is_power_of_2(obj_size)) {
109 size_t objs_per_page = PAGE_SIZE / obj_size;
111 return (idx / objs_per_page) * PAGE_SIZE +
112 (idx % objs_per_page) * obj_size;
114 return idx * obj_size;
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]))
125 #define __genradix_idx_to_offset(_radix, _idx) \
126 __idx_to_offset(_idx, __genradix_obj_size(_radix))
128 void *__genradix_ptr(struct __genradix *, size_t);
131 * genradix_ptr - get a pointer to a genradix entry
132 * @_radix: genradix to access
133 * @_idx: index to fetch
135 * Returns a pointer to entry at @_idx, or NULL if that entry does not exist.
137 #define genradix_ptr(_radix, _idx) \
138 (__genradix_cast(_radix) \
139 __genradix_ptr(&(_radix)->tree, \
140 __genradix_idx_to_offset(_radix, _idx)))
142 void *__genradix_ptr_alloc(struct __genradix *, size_t, gfp_t);
145 * genradix_ptr_alloc - get a pointer to a genradix entry, allocating it
147 * @_radix: genradix to access
148 * @_idx: index to fetch
151 * Returns a pointer to entry at @_idx, or NULL on allocation failure
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), \
159 struct genradix_iter {
165 * genradix_iter_init - initialize a genradix_iter
166 * @_radix: genradix that will be iterated over
167 * @_idx: index to start iterating from
169 #define genradix_iter_init(_radix, _idx) \
170 ((struct genradix_iter) { \
172 .offset = __genradix_idx_to_offset((_radix), (_idx)),\
175 void *__genradix_iter_peek(struct genradix_iter *, struct __genradix *, size_t);
178 * genradix_iter_peek - get first entry at or above iterator's current
180 * @_iter: a genradix_iter
181 * @_radix: genradix being iterated over
183 * If no more entries exist at or above @_iter's current position, returns NULL
185 #define genradix_iter_peek(_iter, _radix) \
186 (__genradix_cast(_radix) \
187 __genradix_iter_peek(_iter, &(_radix)->tree, \
188 __genradix_objs_per_page(_radix)))
190 void *__genradix_iter_peek_prev(struct genradix_iter *, struct __genradix *,
194 * genradix_iter_peek_prev - get first entry at or below iterator's current
196 * @_iter: a genradix_iter
197 * @_radix: genradix being iterated over
199 * If no more entries exist at or below @_iter's current position, returns NULL
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)))
208 static inline void __genradix_iter_advance(struct genradix_iter *iter,
211 if (iter->offset + obj_size < iter->offset) {
212 iter->offset = SIZE_MAX;
213 iter->pos = SIZE_MAX;
217 iter->offset += obj_size;
219 if (!is_power_of_2(obj_size) &&
220 (iter->offset & (PAGE_SIZE - 1)) + obj_size > PAGE_SIZE)
221 iter->offset = round_up(iter->offset, PAGE_SIZE);
226 #define genradix_iter_advance(_iter, _radix) \
227 __genradix_iter_advance(_iter, __genradix_obj_size(_radix))
229 static inline void __genradix_iter_rewind(struct genradix_iter *iter,
232 if (iter->offset == 0 ||
233 iter->offset == SIZE_MAX) {
234 iter->offset = SIZE_MAX;
238 if ((iter->offset & (PAGE_SIZE - 1)) == 0)
239 iter->offset -= PAGE_SIZE % obj_size;
241 iter->offset -= obj_size;
245 #define genradix_iter_rewind(_iter, _radix) \
246 __genradix_iter_rewind(_iter, __genradix_obj_size(_radix))
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))
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
259 * On every iteration, @_p will point to the current entry, and @_iter.pos
260 * will be the current entry's index.
262 #define genradix_for_each(_radix, _iter, _p) \
263 genradix_for_each_from(_radix, _iter, _p, 0)
265 #define genradix_last_pos(_radix) \
266 (SIZE_MAX / PAGE_SIZE * __genradix_objs_per_page(_radix) - 1)
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
274 * On every iteration, @_p will point to the current entry, and @_iter.pos
275 * will be the current entry's index.
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))
282 int __genradix_prealloc(struct __genradix *, size_t, gfp_t);
285 * genradix_prealloc - preallocate entries in a generic radix tree
286 * @_radix: genradix to preallocate
287 * @_nr: number of entries to preallocate
290 * Returns 0 on success, -ENOMEM on failure
292 #define genradix_prealloc(_radix, _nr, _gfp) \
293 __genradix_prealloc(&(_radix)->tree, \
294 __genradix_idx_to_offset(_radix, _nr + 1),\
298 #endif /* _LINUX_GENERIC_RADIX_TREE_H */