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_idx_to_offset(_radix, _idx) \ 121 __idx_to_offset(_idx, __genradix_obj_size(_radix)) 122 123 void *__genradix_ptr(struct __genradix *, size_t); 124 125 /** 126 * genradix_ptr - get a pointer to a genradix entry 127 * @_radix: genradix to access 128 * @_idx: index to fetch 129 * 130 * Returns a pointer to entry at @_idx, or NULL if that entry does not exist. 131 */ 132 #define genradix_ptr(_radix, _idx) \ 133 (__genradix_cast(_radix) \ 134 __genradix_ptr(&(_radix)->tree, \ 135 __genradix_idx_to_offset(_radix, _idx))) 136 137 void *__genradix_ptr_alloc(struct __genradix *, size_t, gfp_t); 138 139 /** 140 * genradix_ptr_alloc - get a pointer to a genradix entry, allocating it 141 * if necessary 142 * @_radix: genradix to access 143 * @_idx: index to fetch 144 * @_gfp: gfp mask 145 * 146 * Returns a pointer to entry at @_idx, or NULL on allocation failure 147 */ 148 #define genradix_ptr_alloc(_radix, _idx, _gfp) \ 149 (__genradix_cast(_radix) \ 150 __genradix_ptr_alloc(&(_radix)->tree, \ 151 __genradix_idx_to_offset(_radix, _idx), \ 152 _gfp)) 153 154 struct genradix_iter { 155 size_t offset; 156 size_t pos; 157 }; 158 159 /** 160 * genradix_iter_init - initialize a genradix_iter 161 * @_radix: genradix that will be iterated over 162 * @_idx: index to start iterating from 163 */ 164 #define genradix_iter_init(_radix, _idx) \ 165 ((struct genradix_iter) { \ 166 .pos = (_idx), \ 167 .offset = __genradix_idx_to_offset((_radix), (_idx)),\ 168 }) 169 170 void *__genradix_iter_peek(struct genradix_iter *, struct __genradix *, size_t); 171 172 /** 173 * genradix_iter_peek - get first entry at or above iterator's current 174 * position 175 * @_iter: a genradix_iter 176 * @_radix: genradix being iterated over 177 * 178 * If no more entries exist at or above @_iter's current position, returns NULL 179 */ 180 #define genradix_iter_peek(_iter, _radix) \ 181 (__genradix_cast(_radix) \ 182 __genradix_iter_peek(_iter, &(_radix)->tree, \ 183 PAGE_SIZE / __genradix_obj_size(_radix))) 184 185 static inline void __genradix_iter_advance(struct genradix_iter *iter, 186 size_t obj_size) 187 { 188 if (iter->offset + obj_size < iter->offset) { 189 iter->offset = SIZE_MAX; 190 iter->pos = SIZE_MAX; 191 return; 192 } 193 194 iter->offset += obj_size; 195 196 if (!is_power_of_2(obj_size) && 197 (iter->offset & (PAGE_SIZE - 1)) + obj_size > PAGE_SIZE) 198 iter->offset = round_up(iter->offset, PAGE_SIZE); 199 200 iter->pos++; 201 } 202 203 #define genradix_iter_advance(_iter, _radix) \ 204 __genradix_iter_advance(_iter, __genradix_obj_size(_radix)) 205 206 #define genradix_for_each_from(_radix, _iter, _p, _start) \ 207 for (_iter = genradix_iter_init(_radix, _start); \ 208 (_p = genradix_iter_peek(&_iter, _radix)) != NULL; \ 209 genradix_iter_advance(&_iter, _radix)) 210 211 /** 212 * genradix_for_each - iterate over entry in a genradix 213 * @_radix: genradix to iterate over 214 * @_iter: a genradix_iter to track current position 215 * @_p: pointer to genradix entry type 216 * 217 * On every iteration, @_p will point to the current entry, and @_iter.pos 218 * will be the current entry's index. 219 */ 220 #define genradix_for_each(_radix, _iter, _p) \ 221 genradix_for_each_from(_radix, _iter, _p, 0) 222 223 int __genradix_prealloc(struct __genradix *, size_t, gfp_t); 224 225 /** 226 * genradix_prealloc - preallocate entries in a generic radix tree 227 * @_radix: genradix to preallocate 228 * @_nr: number of entries to preallocate 229 * @_gfp: gfp mask 230 * 231 * Returns 0 on success, -ENOMEM on failure 232 */ 233 #define genradix_prealloc(_radix, _nr, _gfp) \ 234 __genradix_prealloc(&(_radix)->tree, \ 235 __genradix_idx_to_offset(_radix, _nr + 1),\ 236 _gfp) 237 238 239 #endif /* _LINUX_GENERIC_RADIX_TREE_H */ 240