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1 | /* Private definitions for the generic associative array implementation. |
2 | * | |
3 | * See Documentation/assoc_array.txt 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 */ |