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1408 | serge | 1 | /* |
2 | * include/linux/idr.h |
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3 | * |
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4 | * 2002-10-18 written by Jim Houston jim.houston@ccur.com |
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5 | * Copyright (C) 2002 by Concurrent Computer Corporation |
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6 | * Distributed under the GNU GPL license version 2. |
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7 | * |
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8 | * Small id to pointer translation service avoiding fixed sized |
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9 | * tables. |
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10 | */ |
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11 | |||
12 | #ifndef __IDR_H__ |
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13 | #define __IDR_H__ |
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14 | |||
3391 | Serge | 15 | #include |
1964 | serge | 16 | #include |
1967 | serge | 17 | #include |
1964 | serge | 18 | #include |
1408 | serge | 19 | //#include |
20 | //#include |
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3391 | Serge | 21 | #include |
22 | #include |
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23 | #include |
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1408 | serge | 24 | |
25 | |||
3391 | Serge | 26 | /* |
27 | * We want shallower trees and thus more bits covered at each layer. 8 |
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28 | * bits gives us large enough first layer for most use cases and maximum |
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29 | * tree depth of 4. Each idr_layer is slightly larger than 2k on 64bit and |
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30 | * 1k on 32bit. |
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31 | */ |
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32 | #define IDR_BITS 8 |
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1408 | serge | 33 | #define IDR_SIZE (1 << IDR_BITS) |
34 | #define IDR_MASK ((1 << IDR_BITS)-1) |
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35 | |||
36 | struct idr_layer { |
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3391 | Serge | 37 | int prefix; /* the ID prefix of this idr_layer */ |
38 | DECLARE_BITMAP(bitmap, IDR_SIZE); /* A zero bit means "space here" */ |
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1964 | serge | 39 | struct idr_layer __rcu *ary[1< |
1408 | serge | 40 | int count; /* When zero, we can release it */ |
41 | int layer; /* distance from leaf */ |
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42 | struct rcu_head rcu_head; |
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43 | }; |
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44 | |||
45 | struct idr { |
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3391 | Serge | 46 | struct idr_layer __rcu *hint; /* the last layer allocated from */ |
1964 | serge | 47 | struct idr_layer __rcu *top; |
1408 | serge | 48 | struct idr_layer *id_free; |
3391 | Serge | 49 | int layers; /* only valid w/o concurrent changes */ |
1408 | serge | 50 | int id_free_cnt; |
3391 | Serge | 51 | spinlock_t lock; |
1408 | serge | 52 | }; |
53 | |||
54 | #define IDR_INIT(name) \ |
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55 | { \ |
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3391 | Serge | 56 | .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ |
1408 | serge | 57 | } |
58 | #define DEFINE_IDR(name) struct idr name = IDR_INIT(name) |
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59 | |||
60 | /** |
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1964 | serge | 61 | * DOC: idr sync |
1408 | serge | 62 | * idr synchronization (stolen from radix-tree.h) |
63 | * |
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64 | * idr_find() is able to be called locklessly, using RCU. The caller must |
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65 | * ensure calls to this function are made within rcu_read_lock() regions. |
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66 | * Other readers (lock-free or otherwise) and modifications may be running |
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67 | * concurrently. |
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68 | * |
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69 | * It is still required that the caller manage the synchronization and |
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70 | * lifetimes of the items. So if RCU lock-free lookups are used, typically |
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71 | * this would mean that the items have their own locks, or are amenable to |
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72 | * lock-free access; and that the items are freed by RCU (or only freed after |
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73 | * having been deleted from the idr tree *and* a synchronize_rcu() grace |
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74 | * period). |
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75 | */ |
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76 | |||
77 | /* |
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78 | * This is what we export. |
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79 | */ |
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80 | |||
3391 | Serge | 81 | void *idr_find_slowpath(struct idr *idp, int id); |
1964 | serge | 82 | int idr_pre_get(struct idr *idp, gfp_t gfp_mask); |
1408 | serge | 83 | int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id); |
3391 | Serge | 84 | void idr_preload(gfp_t gfp_mask); |
85 | int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask); |
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1408 | serge | 86 | int idr_for_each(struct idr *idp, |
87 | int (*fn)(int id, void *p, void *data), void *data); |
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88 | void *idr_get_next(struct idr *idp, int *nextid); |
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89 | void *idr_replace(struct idr *idp, void *ptr, int id); |
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90 | void idr_remove(struct idr *idp, int id); |
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3391 | Serge | 91 | void idr_free(struct idr *idp, int id); |
1408 | serge | 92 | void idr_destroy(struct idr *idp); |
93 | void idr_init(struct idr *idp); |
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94 | |||
3391 | Serge | 95 | /** |
96 | * idr_preload_end - end preload section started with idr_preload() |
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97 | * |
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98 | * Each idr_preload() should be matched with an invocation of this |
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99 | * function. See idr_preload() for details. |
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100 | */ |
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101 | static inline void idr_preload_end(void) |
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102 | { |
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103 | // preempt_enable(); |
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104 | } |
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1408 | serge | 105 | |
3391 | Serge | 106 | /** |
107 | * idr_find - return pointer for given id |
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108 | * @idp: idr handle |
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109 | * @id: lookup key |
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110 | * |
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111 | * Return the pointer given the id it has been registered with. A %NULL |
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112 | * return indicates that @id is not valid or you passed %NULL in |
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113 | * idr_get_new(). |
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114 | * |
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115 | * This function can be called under rcu_read_lock(), given that the leaf |
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116 | * pointers lifetimes are correctly managed. |
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117 | */ |
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118 | static inline void *idr_find(struct idr *idr, int id) |
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119 | { |
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120 | struct idr_layer *hint = rcu_dereference_raw(idr->hint); |
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121 | |||
122 | if (hint && (id & ~IDR_MASK) == hint->prefix) |
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123 | return rcu_dereference_raw(hint->ary[id & IDR_MASK]); |
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124 | |||
125 | return idr_find_slowpath(idr, id); |
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126 | } |
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127 | |||
128 | /** |
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129 | * idr_get_new - allocate new idr entry |
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130 | * @idp: idr handle |
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131 | * @ptr: pointer you want associated with the id |
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132 | * @id: pointer to the allocated handle |
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133 | * |
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134 | * Simple wrapper around idr_get_new_above() w/ @starting_id of zero. |
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135 | */ |
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136 | static inline int idr_get_new(struct idr *idp, void *ptr, int *id) |
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137 | { |
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138 | return idr_get_new_above(idp, ptr, 0, id); |
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139 | } |
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140 | |||
141 | /** |
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142 | * idr_for_each_entry - iterate over an idr's elements of a given type |
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143 | * @idp: idr handle |
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144 | * @entry: the type * to use as cursor |
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145 | * @id: id entry's key |
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146 | */ |
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147 | #define idr_for_each_entry(idp, entry, id) \ |
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148 | for (id = 0, entry = (typeof(entry))idr_get_next((idp), &(id)); \ |
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149 | entry != NULL; \ |
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150 | ++id, entry = (typeof(entry))idr_get_next((idp), &(id))) |
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151 | |||
152 | void __idr_remove_all(struct idr *idp); /* don't use */ |
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153 | |||
154 | /** |
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155 | * idr_remove_all - remove all ids from the given idr tree |
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156 | * @idp: idr handle |
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157 | * |
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158 | * If you're trying to destroy @idp, calling idr_destroy() is enough. |
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159 | * This is going away. Don't use. |
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160 | */ |
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161 | static inline void __deprecated idr_remove_all(struct idr *idp) |
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162 | { |
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163 | __idr_remove_all(idp); |
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164 | } |
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165 | |||
1408 | serge | 166 | /* |
167 | * IDA - IDR based id allocator, use when translation from id to |
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168 | * pointer isn't necessary. |
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1964 | serge | 169 | * |
170 | * IDA_BITMAP_LONGS is calculated to be one less to accommodate |
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171 | * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes. |
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1408 | serge | 172 | */ |
173 | #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ |
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1964 | serge | 174 | #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1) |
1408 | serge | 175 | #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) |
176 | |||
177 | struct ida_bitmap { |
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178 | long nr_busy; |
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179 | unsigned long bitmap[IDA_BITMAP_LONGS]; |
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180 | }; |
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181 | |||
182 | struct ida { |
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183 | struct idr idr; |
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184 | struct ida_bitmap *free_bitmap; |
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185 | }; |
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186 | |||
3391 | Serge | 187 | #define IDA_INIT(name) { .idr = IDR_INIT((name).idr), .free_bitmap = NULL, } |
1408 | serge | 188 | #define DEFINE_IDA(name) struct ida name = IDA_INIT(name) |
189 | |||
1964 | serge | 190 | int ida_pre_get(struct ida *ida, gfp_t gfp_mask); |
1408 | serge | 191 | int ida_get_new_above(struct ida *ida, int starting_id, int *p_id); |
192 | void ida_remove(struct ida *ida, int id); |
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193 | void ida_destroy(struct ida *ida); |
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194 | void ida_init(struct ida *ida); |
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195 | |||
3391 | Serge | 196 | void __init idr_init_cache(void); |
1408 | serge | 197 | |
3391 | Serge | 198 | |
199 | |||
1408 | serge | 200 | #endif /* __IDR_H__ */ |