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/limits.h> 42 #include <linux/log2.h> 43 #include <linux/math.h> 44 #include <linux/types.h> 45 46 struct genradix_root; 47 48 struct __genradix { 49 struct genradix_root *root; 50 }; 51 52 /* 53 * NOTE: currently, sizeof(_type) must not be larger than PAGE_SIZE: 54 */ 55 56 #define __GENRADIX_INITIALIZER \ 57 { \ 58 .tree = { \ 59 .root = NULL, \ 60 } \ 61 } 62 63 /* 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 68 * genradix. 69 */ 70 71 #define GENRADIX(_type) \ 72 struct { \ 73 struct __genradix tree; \ 74 _type type[0] __aligned(1); \ 75 } 76 77 #define DEFINE_GENRADIX(_name, _type) \ 78 GENRADIX(_type) _name = __GENRADIX_INITIALIZER 79 80 /** 81 * genradix_init - initialize a genradix 82 * @_radix: genradix to initialize 83 * 84 * Does not fail 85 */ 86 #define genradix_init(_radix) \ 87 do { \ 88 *(_radix) = (typeof(*_radix)) __GENRADIX_INITIALIZER; \ 89 } while (0) 90 91 void __genradix_free(struct __genradix *); 92 93 /** 94 * genradix_free: free all memory owned by a genradix 95 * @_radix: the genradix to free 96 * 97 * After freeing, @_radix will be reinitialized and empty 98 */ 99 #define genradix_free(_radix) __genradix_free(&(_radix)->tree) 100 101 static inline size_t __idx_to_offset(size_t idx, size_t obj_size) 102 { 103 if (__builtin_constant_p(obj_size)) 104 BUILD_BUG_ON(obj_size > PAGE_SIZE); 105 else 106 BUG_ON(obj_size > PAGE_SIZE); 107 108 if (!is_power_of_2(obj_size)) { 109 size_t objs_per_page = PAGE_SIZE / obj_size; 110 111 return (idx / objs_per_page) * PAGE_SIZE + 112 (idx % objs_per_page) * obj_size; 113 } else { 114 return idx * obj_size; 115 } 116 } 117 118 #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])) 124 125 #define __genradix_idx_to_offset(_radix, _idx) \ 126 __idx_to_offset(_idx, __genradix_obj_size(_radix)) 127 128 void *__genradix_ptr(struct __genradix *, size_t); 129 130 /** 131 * genradix_ptr - get a pointer to a genradix entry 132 * @_radix: genradix to access 133 * @_idx: index to fetch 134 * 135 * Returns a pointer to entry at @_idx, or NULL if that entry does not exist. 136 */ 137 #define genradix_ptr(_radix, _idx) \ 138 (__genradix_cast(_radix) \ 139 __genradix_ptr(&(_radix)->tree, \ 140 __genradix_idx_to_offset(_radix, _idx))) 141 142 void *__genradix_ptr_alloc(struct __genradix *, size_t, gfp_t); 143 144 /** 145 * genradix_ptr_alloc - get a pointer to a genradix entry, allocating it 146 * if necessary 147 * @_radix: genradix to access 148 * @_idx: index to fetch 149 * @_gfp: gfp mask 150 * 151 * Returns a pointer to entry at @_idx, or NULL on allocation failure 152 */ 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), \ 157 _gfp)) 158 159 struct genradix_iter { 160 size_t offset; 161 size_t pos; 162 }; 163 164 /** 165 * genradix_iter_init - initialize a genradix_iter 166 * @_radix: genradix that will be iterated over 167 * @_idx: index to start iterating from 168 */ 169 #define genradix_iter_init(_radix, _idx) \ 170 ((struct genradix_iter) { \ 171 .pos = (_idx), \ 172 .offset = __genradix_idx_to_offset((_radix), (_idx)),\ 173 }) 174 175 void *__genradix_iter_peek(struct genradix_iter *, struct __genradix *, size_t); 176 177 /** 178 * genradix_iter_peek - get first entry at or above iterator's current 179 * position 180 * @_iter: a genradix_iter 181 * @_radix: genradix being iterated over 182 * 183 * If no more entries exist at or above @_iter's current position, returns NULL 184 */ 185 #define genradix_iter_peek(_iter, _radix) \ 186 (__genradix_cast(_radix) \ 187 __genradix_iter_peek(_iter, &(_radix)->tree, \ 188 __genradix_objs_per_page(_radix))) 189 190 void *__genradix_iter_peek_prev(struct genradix_iter *, struct __genradix *, 191 size_t, size_t); 192 193 /** 194 * genradix_iter_peek_prev - get first entry at or below iterator's current 195 * position 196 * @_iter: a genradix_iter 197 * @_radix: genradix being iterated over 198 * 199 * If no more entries exist at or below @_iter's current position, returns NULL 200 */ 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))) 207 208 static inline void __genradix_iter_advance(struct genradix_iter *iter, 209 size_t obj_size) 210 { 211 if (iter->offset + obj_size < iter->offset) { 212 iter->offset = SIZE_MAX; 213 iter->pos = SIZE_MAX; 214 return; 215 } 216 217 iter->offset += obj_size; 218 219 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); 222 223 iter->pos++; 224 } 225 226 #define genradix_iter_advance(_iter, _radix) \ 227 __genradix_iter_advance(_iter, __genradix_obj_size(_radix)) 228 229 static inline void __genradix_iter_rewind(struct genradix_iter *iter, 230 size_t obj_size) 231 { 232 if (iter->offset == 0 || 233 iter->offset == SIZE_MAX) { 234 iter->offset = SIZE_MAX; 235 return; 236 } 237 238 if ((iter->offset & (PAGE_SIZE - 1)) == 0) 239 iter->offset -= PAGE_SIZE % obj_size; 240 241 iter->offset -= obj_size; 242 iter->pos--; 243 } 244 245 #define genradix_iter_rewind(_iter, _radix) \ 246 __genradix_iter_rewind(_iter, __genradix_obj_size(_radix)) 247 248 #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)) 252 253 /** 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 258 * 259 * On every iteration, @_p will point to the current entry, and @_iter.pos 260 * will be the current entry's index. 261 */ 262 #define genradix_for_each(_radix, _iter, _p) \ 263 genradix_for_each_from(_radix, _iter, _p, 0) 264 265 #define genradix_last_pos(_radix) \ 266 (SIZE_MAX / PAGE_SIZE * __genradix_objs_per_page(_radix) - 1) 267 268 /** 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 273 * 274 * On every iteration, @_p will point to the current entry, and @_iter.pos 275 * will be the current entry's index. 276 */ 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)) 281 282 int __genradix_prealloc(struct __genradix *, size_t, gfp_t); 283 284 /** 285 * genradix_prealloc - preallocate entries in a generic radix tree 286 * @_radix: genradix to preallocate 287 * @_nr: number of entries to preallocate 288 * @_gfp: gfp mask 289 * 290 * Returns 0 on success, -ENOMEM on failure 291 */ 292 #define genradix_prealloc(_radix, _nr, _gfp) \ 293 __genradix_prealloc(&(_radix)->tree, \ 294 __genradix_idx_to_offset(_radix, _nr + 1),\ 295 _gfp) 296 297 298 #endif /* _LINUX_GENERIC_RADIX_TREE_H */ 299