1 | |
2 | #include <linux/export.h> |
3 | #include <linux/generic-radix-tree.h> |
4 | #include <linux/gfp.h> |
5 | |
6 | #define GENRADIX_ARY (PAGE_SIZE / sizeof(struct genradix_node *)) |
7 | #define GENRADIX_ARY_SHIFT ilog2(GENRADIX_ARY) |
8 | |
9 | struct genradix_node { |
10 | union { |
11 | /* Interior node: */ |
12 | struct genradix_node *children[GENRADIX_ARY]; |
13 | |
14 | /* Leaf: */ |
15 | u8 data[PAGE_SIZE]; |
16 | }; |
17 | }; |
18 | |
19 | static inline int genradix_depth_shift(unsigned depth) |
20 | { |
21 | return PAGE_SHIFT + GENRADIX_ARY_SHIFT * depth; |
22 | } |
23 | |
24 | /* |
25 | * Returns size (of data, in bytes) that a tree of a given depth holds: |
26 | */ |
27 | static inline size_t genradix_depth_size(unsigned depth) |
28 | { |
29 | return 1UL << genradix_depth_shift(depth); |
30 | } |
31 | |
32 | /* depth that's needed for a genradix that can address up to ULONG_MAX: */ |
33 | #define GENRADIX_MAX_DEPTH \ |
34 | DIV_ROUND_UP(BITS_PER_LONG - PAGE_SHIFT, GENRADIX_ARY_SHIFT) |
35 | |
36 | #define GENRADIX_DEPTH_MASK \ |
37 | ((unsigned long) (roundup_pow_of_two(GENRADIX_MAX_DEPTH + 1) - 1)) |
38 | |
39 | unsigned genradix_root_to_depth(struct genradix_root *r) |
40 | { |
41 | return (unsigned long) r & GENRADIX_DEPTH_MASK; |
42 | } |
43 | |
44 | struct genradix_node *genradix_root_to_node(struct genradix_root *r) |
45 | { |
46 | return (void *) ((unsigned long) r & ~GENRADIX_DEPTH_MASK); |
47 | } |
48 | |
49 | /* |
50 | * Returns pointer to the specified byte @offset within @radix, or NULL if not |
51 | * allocated |
52 | */ |
53 | void *__genradix_ptr(struct __genradix *radix, size_t offset) |
54 | { |
55 | struct genradix_root *r = READ_ONCE(radix->root); |
56 | struct genradix_node *n = genradix_root_to_node(r); |
57 | unsigned level = genradix_root_to_depth(r); |
58 | |
59 | if (ilog2(offset) >= genradix_depth_shift(level)) |
60 | return NULL; |
61 | |
62 | while (1) { |
63 | if (!n) |
64 | return NULL; |
65 | if (!level) |
66 | break; |
67 | |
68 | level--; |
69 | |
70 | n = n->children[offset >> genradix_depth_shift(level)]; |
71 | offset &= genradix_depth_size(level) - 1; |
72 | } |
73 | |
74 | return &n->data[offset]; |
75 | } |
76 | EXPORT_SYMBOL(__genradix_ptr); |
77 | |
78 | /* |
79 | * Returns pointer to the specified byte @offset within @radix, allocating it if |
80 | * necessary - newly allocated slots are always zeroed out: |
81 | */ |
82 | void *__genradix_ptr_alloc(struct __genradix *radix, size_t offset, |
83 | gfp_t gfp_mask) |
84 | { |
85 | struct genradix_root *v = READ_ONCE(radix->root); |
86 | struct genradix_node *n, *new_node = NULL; |
87 | unsigned level; |
88 | |
89 | /* Increase tree depth if necessary: */ |
90 | while (1) { |
91 | struct genradix_root *r = v, *new_root; |
92 | |
93 | n = genradix_root_to_node(r); |
94 | level = genradix_root_to_depth(r); |
95 | |
96 | if (n && ilog2(offset) < genradix_depth_shift(level)) |
97 | break; |
98 | |
99 | if (!new_node) { |
100 | new_node = (void *) |
101 | __get_free_page(gfp_mask|__GFP_ZERO); |
102 | if (!new_node) |
103 | return NULL; |
104 | } |
105 | |
106 | new_node->children[0] = n; |
107 | new_root = ((struct genradix_root *) |
108 | ((unsigned long) new_node | (n ? level + 1 : 0))); |
109 | |
110 | if ((v = cmpxchg_release(&radix->root, r, new_root)) == r) { |
111 | v = new_root; |
112 | new_node = NULL; |
113 | } |
114 | } |
115 | |
116 | while (level--) { |
117 | struct genradix_node **p = |
118 | &n->children[offset >> genradix_depth_shift(level)]; |
119 | offset &= genradix_depth_size(level) - 1; |
120 | |
121 | n = READ_ONCE(*p); |
122 | if (!n) { |
123 | if (!new_node) { |
124 | new_node = (void *) |
125 | __get_free_page(gfp_mask|__GFP_ZERO); |
126 | if (!new_node) |
127 | return NULL; |
128 | } |
129 | |
130 | if (!(n = cmpxchg_release(p, NULL, new_node))) |
131 | swap(n, new_node); |
132 | } |
133 | } |
134 | |
135 | if (new_node) |
136 | free_page((unsigned long) new_node); |
137 | |
138 | return &n->data[offset]; |
139 | } |
140 | EXPORT_SYMBOL(__genradix_ptr_alloc); |
141 | |
142 | void *__genradix_iter_peek(struct genradix_iter *iter, |
143 | struct __genradix *radix, |
144 | size_t objs_per_page) |
145 | { |
146 | struct genradix_root *r; |
147 | struct genradix_node *n; |
148 | unsigned level, i; |
149 | restart: |
150 | r = READ_ONCE(radix->root); |
151 | if (!r) |
152 | return NULL; |
153 | |
154 | n = genradix_root_to_node(r); |
155 | level = genradix_root_to_depth(r); |
156 | |
157 | if (ilog2(iter->offset) >= genradix_depth_shift(level)) |
158 | return NULL; |
159 | |
160 | while (level) { |
161 | level--; |
162 | |
163 | i = (iter->offset >> genradix_depth_shift(level)) & |
164 | (GENRADIX_ARY - 1); |
165 | |
166 | while (!n->children[i]) { |
167 | i++; |
168 | iter->offset = round_down(iter->offset + |
169 | genradix_depth_size(level), |
170 | genradix_depth_size(level)); |
171 | iter->pos = (iter->offset >> PAGE_SHIFT) * |
172 | objs_per_page; |
173 | if (i == GENRADIX_ARY) |
174 | goto restart; |
175 | } |
176 | |
177 | n = n->children[i]; |
178 | } |
179 | |
180 | return &n->data[iter->offset & (PAGE_SIZE - 1)]; |
181 | } |
182 | EXPORT_SYMBOL(__genradix_iter_peek); |
183 | |
184 | static void genradix_free_recurse(struct genradix_node *n, unsigned level) |
185 | { |
186 | if (level) { |
187 | unsigned i; |
188 | |
189 | for (i = 0; i < GENRADIX_ARY; i++) |
190 | if (n->children[i]) |
191 | genradix_free_recurse(n->children[i], level - 1); |
192 | } |
193 | |
194 | free_page((unsigned long) n); |
195 | } |
196 | |
197 | int __genradix_prealloc(struct __genradix *radix, size_t size, |
198 | gfp_t gfp_mask) |
199 | { |
200 | size_t offset; |
201 | |
202 | for (offset = 0; offset < size; offset += PAGE_SIZE) |
203 | if (!__genradix_ptr_alloc(radix, offset, gfp_mask)) |
204 | return -ENOMEM; |
205 | |
206 | return 0; |
207 | } |
208 | EXPORT_SYMBOL(__genradix_prealloc); |
209 | |
210 | void __genradix_free(struct __genradix *radix) |
211 | { |
212 | struct genradix_root *r = xchg(&radix->root, NULL); |
213 | |
214 | genradix_free_recurse(genradix_root_to_node(r), |
215 | genradix_root_to_depth(r)); |
216 | } |
217 | EXPORT_SYMBOL(__genradix_free); |
218 | |