1 /* Private definitions for the generic associative array implementation. 2 * 3 * See Documentation/core-api/assoc_array.rst for information. 4 * 5 * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved. 6 * Written by David Howells (dhowells@redhat.com) 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public Licence 10 * as published by the Free Software Foundation; either version 11 * 2 of the Licence, or (at your option) any later version. 12 */ 13 14 #ifndef _LINUX_ASSOC_ARRAY_PRIV_H 15 #define _LINUX_ASSOC_ARRAY_PRIV_H 16 17 #ifdef CONFIG_ASSOCIATIVE_ARRAY 18 19 #include <linux/assoc_array.h> 20 21 #define ASSOC_ARRAY_FAN_OUT 16 /* Number of slots per node */ 22 #define ASSOC_ARRAY_FAN_MASK (ASSOC_ARRAY_FAN_OUT - 1) 23 #define ASSOC_ARRAY_LEVEL_STEP (ilog2(ASSOC_ARRAY_FAN_OUT)) 24 #define ASSOC_ARRAY_LEVEL_STEP_MASK (ASSOC_ARRAY_LEVEL_STEP - 1) 25 #define ASSOC_ARRAY_KEY_CHUNK_MASK (ASSOC_ARRAY_KEY_CHUNK_SIZE - 1) 26 #define ASSOC_ARRAY_KEY_CHUNK_SHIFT (ilog2(BITS_PER_LONG)) 27 28 /* 29 * Undefined type representing a pointer with type information in the bottom 30 * two bits. 31 */ 32 struct assoc_array_ptr; 33 34 /* 35 * An N-way node in the tree. 36 * 37 * Each slot contains one of four things: 38 * 39 * (1) Nothing (NULL). 40 * 41 * (2) A leaf object (pointer types 0). 42 * 43 * (3) A next-level node (pointer type 1, subtype 0). 44 * 45 * (4) A shortcut (pointer type 1, subtype 1). 46 * 47 * The tree is optimised for search-by-ID, but permits reasonable iteration 48 * also. 49 * 50 * The tree is navigated by constructing an index key consisting of an array of 51 * segments, where each segment is ilog2(ASSOC_ARRAY_FAN_OUT) bits in size. 52 * 53 * The segments correspond to levels of the tree (the first segment is used at 54 * level 0, the second at level 1, etc.). 55 */ 56 struct assoc_array_node { 57 struct assoc_array_ptr *back_pointer; 58 u8 parent_slot; 59 struct assoc_array_ptr *slots[ASSOC_ARRAY_FAN_OUT]; 60 unsigned long nr_leaves_on_branch; 61 }; 62 63 /* 64 * A shortcut through the index space out to where a collection of nodes/leaves 65 * with the same IDs live. 66 */ 67 struct assoc_array_shortcut { 68 struct assoc_array_ptr *back_pointer; 69 int parent_slot; 70 int skip_to_level; 71 struct assoc_array_ptr *next_node; 72 unsigned long index_key[]; 73 }; 74 75 /* 76 * Preallocation cache. 77 */ 78 struct assoc_array_edit { 79 struct rcu_head rcu; 80 struct assoc_array *array; 81 const struct assoc_array_ops *ops; 82 const struct assoc_array_ops *ops_for_excised_subtree; 83 struct assoc_array_ptr *leaf; 84 struct assoc_array_ptr **leaf_p; 85 struct assoc_array_ptr *dead_leaf; 86 struct assoc_array_ptr *new_meta[3]; 87 struct assoc_array_ptr *excised_meta[1]; 88 struct assoc_array_ptr *excised_subtree; 89 struct assoc_array_ptr **set_backpointers[ASSOC_ARRAY_FAN_OUT]; 90 struct assoc_array_ptr *set_backpointers_to; 91 struct assoc_array_node *adjust_count_on; 92 long adjust_count_by; 93 struct { 94 struct assoc_array_ptr **ptr; 95 struct assoc_array_ptr *to; 96 } set[2]; 97 struct { 98 u8 *p; 99 u8 to; 100 } set_parent_slot[1]; 101 u8 segment_cache[ASSOC_ARRAY_FAN_OUT + 1]; 102 }; 103 104 /* 105 * Internal tree member pointers are marked in the bottom one or two bits to 106 * indicate what type they are so that we don't have to look behind every 107 * pointer to see what it points to. 108 * 109 * We provide functions to test type annotations and to create and translate 110 * the annotated pointers. 111 */ 112 #define ASSOC_ARRAY_PTR_TYPE_MASK 0x1UL 113 #define ASSOC_ARRAY_PTR_LEAF_TYPE 0x0UL /* Points to leaf (or nowhere) */ 114 #define ASSOC_ARRAY_PTR_META_TYPE 0x1UL /* Points to node or shortcut */ 115 #define ASSOC_ARRAY_PTR_SUBTYPE_MASK 0x2UL 116 #define ASSOC_ARRAY_PTR_NODE_SUBTYPE 0x0UL 117 #define ASSOC_ARRAY_PTR_SHORTCUT_SUBTYPE 0x2UL 118 119 static inline bool assoc_array_ptr_is_meta(const struct assoc_array_ptr *x) 120 { 121 return (unsigned long)x & ASSOC_ARRAY_PTR_TYPE_MASK; 122 } 123 static inline bool assoc_array_ptr_is_leaf(const struct assoc_array_ptr *x) 124 { 125 return !assoc_array_ptr_is_meta(x); 126 } 127 static inline bool assoc_array_ptr_is_shortcut(const struct assoc_array_ptr *x) 128 { 129 return (unsigned long)x & ASSOC_ARRAY_PTR_SUBTYPE_MASK; 130 } 131 static inline bool assoc_array_ptr_is_node(const struct assoc_array_ptr *x) 132 { 133 return !assoc_array_ptr_is_shortcut(x); 134 } 135 136 static inline void *assoc_array_ptr_to_leaf(const struct assoc_array_ptr *x) 137 { 138 return (void *)((unsigned long)x & ~ASSOC_ARRAY_PTR_TYPE_MASK); 139 } 140 141 static inline 142 unsigned long __assoc_array_ptr_to_meta(const struct assoc_array_ptr *x) 143 { 144 return (unsigned long)x & 145 ~(ASSOC_ARRAY_PTR_SUBTYPE_MASK | ASSOC_ARRAY_PTR_TYPE_MASK); 146 } 147 static inline 148 struct assoc_array_node *assoc_array_ptr_to_node(const struct assoc_array_ptr *x) 149 { 150 return (struct assoc_array_node *)__assoc_array_ptr_to_meta(x); 151 } 152 static inline 153 struct assoc_array_shortcut *assoc_array_ptr_to_shortcut(const struct assoc_array_ptr *x) 154 { 155 return (struct assoc_array_shortcut *)__assoc_array_ptr_to_meta(x); 156 } 157 158 static inline 159 struct assoc_array_ptr *__assoc_array_x_to_ptr(const void *p, unsigned long t) 160 { 161 return (struct assoc_array_ptr *)((unsigned long)p | t); 162 } 163 static inline 164 struct assoc_array_ptr *assoc_array_leaf_to_ptr(const void *p) 165 { 166 return __assoc_array_x_to_ptr(p, ASSOC_ARRAY_PTR_LEAF_TYPE); 167 } 168 static inline 169 struct assoc_array_ptr *assoc_array_node_to_ptr(const struct assoc_array_node *p) 170 { 171 return __assoc_array_x_to_ptr( 172 p, ASSOC_ARRAY_PTR_META_TYPE | ASSOC_ARRAY_PTR_NODE_SUBTYPE); 173 } 174 static inline 175 struct assoc_array_ptr *assoc_array_shortcut_to_ptr(const struct assoc_array_shortcut *p) 176 { 177 return __assoc_array_x_to_ptr( 178 p, ASSOC_ARRAY_PTR_META_TYPE | ASSOC_ARRAY_PTR_SHORTCUT_SUBTYPE); 179 } 180 181 #endif /* CONFIG_ASSOCIATIVE_ARRAY */ 182 #endif /* _LINUX_ASSOC_ARRAY_PRIV_H */ 183