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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 */ |
5056 | serge | 38 | int layer; /* distance from leaf */ |
1964 | serge | 39 | struct idr_layer __rcu *ary[1< |
1408 | serge | 40 | int count; /* When zero, we can release it */ |
5056 | serge | 41 | union { |
42 | /* A zero bit means "space here" */ |
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43 | DECLARE_BITMAP(bitmap, IDR_SIZE); |
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1408 | serge | 44 | struct rcu_head rcu_head; |
5056 | serge | 45 | }; |
1408 | serge | 46 | }; |
47 | |||
48 | struct idr { |
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3391 | Serge | 49 | struct idr_layer __rcu *hint; /* the last layer allocated from */ |
1964 | serge | 50 | struct idr_layer __rcu *top; |
3391 | Serge | 51 | int layers; /* only valid w/o concurrent changes */ |
4065 | Serge | 52 | int cur; /* current pos for cyclic allocation */ |
3391 | Serge | 53 | spinlock_t lock; |
5056 | serge | 54 | int id_free_cnt; |
55 | struct idr_layer *id_free; |
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1408 | serge | 56 | }; |
57 | |||
58 | #define IDR_INIT(name) \ |
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59 | { \ |
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3391 | Serge | 60 | .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ |
1408 | serge | 61 | } |
62 | #define DEFINE_IDR(name) struct idr name = IDR_INIT(name) |
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63 | |||
64 | /** |
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1964 | serge | 65 | * DOC: idr sync |
1408 | serge | 66 | * idr synchronization (stolen from radix-tree.h) |
67 | * |
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68 | * idr_find() is able to be called locklessly, using RCU. The caller must |
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69 | * ensure calls to this function are made within rcu_read_lock() regions. |
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70 | * Other readers (lock-free or otherwise) and modifications may be running |
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71 | * concurrently. |
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72 | * |
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73 | * It is still required that the caller manage the synchronization and |
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74 | * lifetimes of the items. So if RCU lock-free lookups are used, typically |
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75 | * this would mean that the items have their own locks, or are amenable to |
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76 | * lock-free access; and that the items are freed by RCU (or only freed after |
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77 | * having been deleted from the idr tree *and* a synchronize_rcu() grace |
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78 | * period). |
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79 | */ |
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80 | |||
81 | /* |
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82 | * This is what we export. |
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83 | */ |
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84 | |||
3391 | Serge | 85 | void *idr_find_slowpath(struct idr *idp, int id); |
86 | void idr_preload(gfp_t gfp_mask); |
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87 | int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask); |
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4065 | Serge | 88 | int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask); |
1408 | serge | 89 | int idr_for_each(struct idr *idp, |
90 | int (*fn)(int id, void *p, void *data), void *data); |
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91 | void *idr_get_next(struct idr *idp, int *nextid); |
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92 | void *idr_replace(struct idr *idp, void *ptr, int id); |
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93 | void idr_remove(struct idr *idp, int id); |
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94 | void idr_destroy(struct idr *idp); |
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95 | void idr_init(struct idr *idp); |
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5056 | serge | 96 | bool idr_is_empty(struct idr *idp); |
1408 | serge | 97 | |
3391 | Serge | 98 | /** |
99 | * idr_preload_end - end preload section started with idr_preload() |
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100 | * |
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101 | * Each idr_preload() should be matched with an invocation of this |
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102 | * function. See idr_preload() for details. |
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103 | */ |
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104 | static inline void idr_preload_end(void) |
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105 | { |
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106 | // preempt_enable(); |
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107 | } |
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1408 | serge | 108 | |
3391 | Serge | 109 | /** |
110 | * idr_find - return pointer for given id |
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4065 | Serge | 111 | * @idr: idr handle |
3391 | Serge | 112 | * @id: lookup key |
113 | * |
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114 | * Return the pointer given the id it has been registered with. A %NULL |
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115 | * return indicates that @id is not valid or you passed %NULL in |
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116 | * idr_get_new(). |
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117 | * |
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118 | * This function can be called under rcu_read_lock(), given that the leaf |
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119 | * pointers lifetimes are correctly managed. |
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120 | */ |
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121 | static inline void *idr_find(struct idr *idr, int id) |
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122 | { |
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123 | struct idr_layer *hint = rcu_dereference_raw(idr->hint); |
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124 | |||
125 | if (hint && (id & ~IDR_MASK) == hint->prefix) |
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126 | return rcu_dereference_raw(hint->ary[id & IDR_MASK]); |
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127 | |||
128 | return idr_find_slowpath(idr, id); |
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129 | } |
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130 | |||
131 | /** |
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4065 | Serge | 132 | * idr_for_each_entry - iterate over an idr's elements of a given type |
133 | * @idp: idr handle |
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134 | * @entry: the type * to use as cursor |
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135 | * @id: id entry's key |
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136 | * |
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137 | * @entry and @id do not need to be initialized before the loop, and |
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138 | * after normal terminatinon @entry is left with the value NULL. This |
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139 | * is convenient for a "not found" value. |
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140 | */ |
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141 | #define idr_for_each_entry(idp, entry, id) \ |
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142 | for (id = 0; ((entry) = idr_get_next(idp, &(id))) != NULL; ++id) |
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143 | |||
144 | /* |
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1408 | serge | 145 | * IDA - IDR based id allocator, use when translation from id to |
146 | * pointer isn't necessary. |
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1964 | serge | 147 | * |
148 | * IDA_BITMAP_LONGS is calculated to be one less to accommodate |
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149 | * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes. |
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1408 | serge | 150 | */ |
151 | #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ |
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1964 | serge | 152 | #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1) |
1408 | serge | 153 | #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) |
154 | |||
155 | struct ida_bitmap { |
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156 | long nr_busy; |
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157 | unsigned long bitmap[IDA_BITMAP_LONGS]; |
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158 | }; |
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159 | |||
160 | struct ida { |
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161 | struct idr idr; |
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162 | struct ida_bitmap *free_bitmap; |
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163 | }; |
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164 | |||
3391 | Serge | 165 | #define IDA_INIT(name) { .idr = IDR_INIT((name).idr), .free_bitmap = NULL, } |
1408 | serge | 166 | #define DEFINE_IDA(name) struct ida name = IDA_INIT(name) |
167 | |||
1964 | serge | 168 | int ida_pre_get(struct ida *ida, gfp_t gfp_mask); |
1408 | serge | 169 | int ida_get_new_above(struct ida *ida, int starting_id, int *p_id); |
170 | void ida_remove(struct ida *ida, int id); |
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171 | void ida_destroy(struct ida *ida); |
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172 | void ida_init(struct ida *ida); |
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173 | |||
4065 | Serge | 174 | int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, |
175 | gfp_t gfp_mask); |
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176 | void ida_simple_remove(struct ida *ida, unsigned int id); |
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1408 | serge | 177 | |
4065 | Serge | 178 | /** |
179 | * ida_get_new - allocate new ID |
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180 | * @ida: idr handle |
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181 | * @p_id: pointer to the allocated handle |
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182 | * |
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183 | * Simple wrapper around ida_get_new_above() w/ @starting_id of zero. |
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184 | */ |
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185 | static inline int ida_get_new(struct ida *ida, int *p_id) |
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186 | { |
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187 | return ida_get_new_above(ida, 0, p_id); |
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188 | } |
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3391 | Serge | 189 | |
4065 | Serge | 190 | void __init idr_init_cache(void); |
3391 | Serge | 191 | |
1408 | serge | 192 | #endif /* __IDR_H__ */ |