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