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