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