1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* Private definitions for the generic associative array implementation. 3 * 4 * See Documentation/core-api/assoc_array.rst for information. 5 * 6 * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved. 7 * Written by David Howells (dhowells@redhat.com) 8 */ 9 10 #ifndef _LINUX_ASSOC_ARRAY_PRIV_H 11 #define _LINUX_ASSOC_ARRAY_PRIV_H 12 13 #ifdef CONFIG_ASSOCIATIVE_ARRAY 14 15 #include <linux/assoc_array.h> 16 17 #define ASSOC_ARRAY_FAN_OUT 16 /* Number of slots per node */ 18 #define ASSOC_ARRAY_FAN_MASK (ASSOC_ARRAY_FAN_OUT - 1) 19 #define ASSOC_ARRAY_LEVEL_STEP (ilog2(ASSOC_ARRAY_FAN_OUT)) 20 #define ASSOC_ARRAY_LEVEL_STEP_MASK (ASSOC_ARRAY_LEVEL_STEP - 1) 21 #define ASSOC_ARRAY_KEY_CHUNK_MASK (ASSOC_ARRAY_KEY_CHUNK_SIZE - 1) 22 #define ASSOC_ARRAY_KEY_CHUNK_SHIFT (ilog2(BITS_PER_LONG)) 23 24 /* 25 * Undefined type representing a pointer with type information in the bottom 26 * two bits. 27 */ 28 struct assoc_array_ptr; 29 30 /* 31 * An N-way node in the tree. 32 * 33 * Each slot contains one of four things: 34 * 35 * (1) Nothing (NULL). 36 * 37 * (2) A leaf object (pointer types 0). 38 * 39 * (3) A next-level node (pointer type 1, subtype 0). 40 * 41 * (4) A shortcut (pointer type 1, subtype 1). 42 * 43 * The tree is optimised for search-by-ID, but permits reasonable iteration 44 * also. 45 * 46 * The tree is navigated by constructing an index key consisting of an array of 47 * segments, where each segment is ilog2(ASSOC_ARRAY_FAN_OUT) bits in size. 48 * 49 * The segments correspond to levels of the tree (the first segment is used at 50 * level 0, the second at level 1, etc.). 51 */ 52 struct assoc_array_node { 53 struct assoc_array_ptr *back_pointer; 54 u8 parent_slot; 55 struct assoc_array_ptr *slots[ASSOC_ARRAY_FAN_OUT]; 56 unsigned long nr_leaves_on_branch; 57 }; 58 59 /* 60 * A shortcut through the index space out to where a collection of nodes/leaves 61 * with the same IDs live. 62 */ 63 struct assoc_array_shortcut { 64 struct assoc_array_ptr *back_pointer; 65 int parent_slot; 66 int skip_to_level; 67 struct assoc_array_ptr *next_node; 68 unsigned long index_key[]; 69 }; 70 71 /* 72 * Preallocation cache. 73 */ 74 struct assoc_array_edit { 75 struct rcu_head rcu; 76 struct assoc_array *array; 77 const struct assoc_array_ops *ops; 78 const struct assoc_array_ops *ops_for_excised_subtree; 79 struct assoc_array_ptr *leaf; 80 struct assoc_array_ptr **leaf_p; 81 struct assoc_array_ptr *dead_leaf; 82 struct assoc_array_ptr *new_meta[3]; 83 struct assoc_array_ptr *excised_meta[1]; 84 struct assoc_array_ptr *excised_subtree; 85 struct assoc_array_ptr **set_backpointers[ASSOC_ARRAY_FAN_OUT]; 86 struct assoc_array_ptr *set_backpointers_to; 87 struct assoc_array_node *adjust_count_on; 88 long adjust_count_by; 89 struct { 90 struct assoc_array_ptr **ptr; 91 struct assoc_array_ptr *to; 92 } set[2]; 93 struct { 94 u8 *p; 95 u8 to; 96 } set_parent_slot[1]; 97 u8 segment_cache[ASSOC_ARRAY_FAN_OUT + 1]; 98 }; 99 100 /* 101 * Internal tree member pointers are marked in the bottom one or two bits to 102 * indicate what type they are so that we don't have to look behind every 103 * pointer to see what it points to. 104 * 105 * We provide functions to test type annotations and to create and translate 106 * the annotated pointers. 107 */ 108 #define ASSOC_ARRAY_PTR_TYPE_MASK 0x1UL 109 #define ASSOC_ARRAY_PTR_LEAF_TYPE 0x0UL /* Points to leaf (or nowhere) */ 110 #define ASSOC_ARRAY_PTR_META_TYPE 0x1UL /* Points to node or shortcut */ 111 #define ASSOC_ARRAY_PTR_SUBTYPE_MASK 0x2UL 112 #define ASSOC_ARRAY_PTR_NODE_SUBTYPE 0x0UL 113 #define ASSOC_ARRAY_PTR_SHORTCUT_SUBTYPE 0x2UL 114 assoc_array_ptr_is_meta(const struct assoc_array_ptr * x)115 static inline bool assoc_array_ptr_is_meta(const struct assoc_array_ptr *x) 116 { 117 return (unsigned long)x & ASSOC_ARRAY_PTR_TYPE_MASK; 118 } assoc_array_ptr_is_leaf(const struct assoc_array_ptr * x)119 static inline bool assoc_array_ptr_is_leaf(const struct assoc_array_ptr *x) 120 { 121 return !assoc_array_ptr_is_meta(x); 122 } assoc_array_ptr_is_shortcut(const struct assoc_array_ptr * x)123 static inline bool assoc_array_ptr_is_shortcut(const struct assoc_array_ptr *x) 124 { 125 return (unsigned long)x & ASSOC_ARRAY_PTR_SUBTYPE_MASK; 126 } assoc_array_ptr_is_node(const struct assoc_array_ptr * x)127 static inline bool assoc_array_ptr_is_node(const struct assoc_array_ptr *x) 128 { 129 return !assoc_array_ptr_is_shortcut(x); 130 } 131 assoc_array_ptr_to_leaf(const struct assoc_array_ptr * x)132 static inline void *assoc_array_ptr_to_leaf(const struct assoc_array_ptr *x) 133 { 134 return (void *)((unsigned long)x & ~ASSOC_ARRAY_PTR_TYPE_MASK); 135 } 136 137 static inline __assoc_array_ptr_to_meta(const struct assoc_array_ptr * x)138 unsigned long __assoc_array_ptr_to_meta(const struct assoc_array_ptr *x) 139 { 140 return (unsigned long)x & 141 ~(ASSOC_ARRAY_PTR_SUBTYPE_MASK | ASSOC_ARRAY_PTR_TYPE_MASK); 142 } 143 static inline assoc_array_ptr_to_node(const struct assoc_array_ptr * x)144 struct assoc_array_node *assoc_array_ptr_to_node(const struct assoc_array_ptr *x) 145 { 146 return (struct assoc_array_node *)__assoc_array_ptr_to_meta(x); 147 } 148 static inline assoc_array_ptr_to_shortcut(const struct assoc_array_ptr * x)149 struct assoc_array_shortcut *assoc_array_ptr_to_shortcut(const struct assoc_array_ptr *x) 150 { 151 return (struct assoc_array_shortcut *)__assoc_array_ptr_to_meta(x); 152 } 153 154 static inline __assoc_array_x_to_ptr(const void * p,unsigned long t)155 struct assoc_array_ptr *__assoc_array_x_to_ptr(const void *p, unsigned long t) 156 { 157 return (struct assoc_array_ptr *)((unsigned long)p | t); 158 } 159 static inline assoc_array_leaf_to_ptr(const void * p)160 struct assoc_array_ptr *assoc_array_leaf_to_ptr(const void *p) 161 { 162 return __assoc_array_x_to_ptr(p, ASSOC_ARRAY_PTR_LEAF_TYPE); 163 } 164 static inline assoc_array_node_to_ptr(const struct assoc_array_node * p)165 struct assoc_array_ptr *assoc_array_node_to_ptr(const struct assoc_array_node *p) 166 { 167 return __assoc_array_x_to_ptr( 168 p, ASSOC_ARRAY_PTR_META_TYPE | ASSOC_ARRAY_PTR_NODE_SUBTYPE); 169 } 170 static inline assoc_array_shortcut_to_ptr(const struct assoc_array_shortcut * p)171 struct assoc_array_ptr *assoc_array_shortcut_to_ptr(const struct assoc_array_shortcut *p) 172 { 173 return __assoc_array_x_to_ptr( 174 p, ASSOC_ARRAY_PTR_META_TYPE | ASSOC_ARRAY_PTR_SHORTCUT_SUBTYPE); 175 } 176 177 #endif /* CONFIG_ASSOCIATIVE_ARRAY */ 178 #endif /* _LINUX_ASSOC_ARRAY_PRIV_H */ 179