Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * include/linux/idr.h | |
3 | * | |
4 | * 2002-10-18 written by Jim Houston jim.houston@ccur.com | |
5 | * Copyright (C) 2002 by Concurrent Computer Corporation | |
6 | * Distributed under the GNU GPL license version 2. | |
7 | * | |
8 | * Small id to pointer translation service avoiding fixed sized | |
9 | * tables. | |
10 | */ | |
f668ab1a LT |
11 | |
12 | #ifndef __IDR_H__ | |
13 | #define __IDR_H__ | |
14 | ||
1da177e4 LT |
15 | #include <linux/types.h> |
16 | #include <linux/bitops.h> | |
199f0ca5 | 17 | #include <linux/init.h> |
2027d1ab | 18 | #include <linux/rcupdate.h> |
1da177e4 | 19 | |
050a6b47 TH |
20 | /* |
21 | * We want shallower trees and thus more bits covered at each layer. 8 | |
22 | * bits gives us large enough first layer for most use cases and maximum | |
23 | * tree depth of 4. Each idr_layer is slightly larger than 2k on 64bit and | |
24 | * 1k on 32bit. | |
25 | */ | |
26 | #define IDR_BITS 8 | |
1da177e4 LT |
27 | #define IDR_SIZE (1 << IDR_BITS) |
28 | #define IDR_MASK ((1 << IDR_BITS)-1) | |
29 | ||
1da177e4 | 30 | struct idr_layer { |
54616283 | 31 | int prefix; /* the ID prefix of this idr_layer */ |
1d9b2e1e | 32 | DECLARE_BITMAP(bitmap, IDR_SIZE); /* A zero bit means "space here" */ |
d2c2486b | 33 | struct idr_layer __rcu *ary[1<<IDR_BITS]; |
4106ecaf TH |
34 | int count; /* When zero, we can release it */ |
35 | int layer; /* distance from leaf */ | |
36 | struct rcu_head rcu_head; | |
1da177e4 LT |
37 | }; |
38 | ||
39 | struct idr { | |
0ffc2a9c | 40 | struct idr_layer __rcu *hint; /* the last layer allocated from */ |
4106ecaf TH |
41 | struct idr_layer __rcu *top; |
42 | struct idr_layer *id_free; | |
43 | int layers; /* only valid w/o concurrent changes */ | |
44 | int id_free_cnt; | |
3e6628c4 | 45 | int cur; /* current pos for cyclic allocation */ |
4106ecaf | 46 | spinlock_t lock; |
1da177e4 LT |
47 | }; |
48 | ||
4106ecaf TH |
49 | #define IDR_INIT(name) \ |
50 | { \ | |
51 | .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ | |
1da177e4 LT |
52 | } |
53 | #define DEFINE_IDR(name) struct idr name = IDR_INIT(name) | |
54 | ||
f9c46d6e | 55 | /** |
56083ab1 | 56 | * DOC: idr sync |
f9c46d6e ND |
57 | * idr synchronization (stolen from radix-tree.h) |
58 | * | |
59 | * idr_find() is able to be called locklessly, using RCU. The caller must | |
60 | * ensure calls to this function are made within rcu_read_lock() regions. | |
61 | * Other readers (lock-free or otherwise) and modifications may be running | |
62 | * concurrently. | |
63 | * | |
64 | * It is still required that the caller manage the synchronization and | |
65 | * lifetimes of the items. So if RCU lock-free lookups are used, typically | |
66 | * this would mean that the items have their own locks, or are amenable to | |
67 | * lock-free access; and that the items are freed by RCU (or only freed after | |
68 | * having been deleted from the idr tree *and* a synchronize_rcu() grace | |
69 | * period). | |
70 | */ | |
71 | ||
1da177e4 LT |
72 | /* |
73 | * This is what we export. | |
74 | */ | |
75 | ||
0ffc2a9c | 76 | void *idr_find_slowpath(struct idr *idp, int id); |
d5c7409f TH |
77 | void idr_preload(gfp_t gfp_mask); |
78 | int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask); | |
3e6628c4 | 79 | int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask); |
96d7fa42 KH |
80 | int idr_for_each(struct idr *idp, |
81 | int (*fn)(int id, void *p, void *data), void *data); | |
38460b48 | 82 | void *idr_get_next(struct idr *idp, int *nextid); |
5806f07c | 83 | void *idr_replace(struct idr *idp, void *ptr, int id); |
1da177e4 | 84 | void idr_remove(struct idr *idp, int id); |
8d3b3591 | 85 | void idr_destroy(struct idr *idp); |
1da177e4 | 86 | void idr_init(struct idr *idp); |
05f7a7d6 | 87 | bool idr_is_empty(struct idr *idp); |
f668ab1a | 88 | |
d5c7409f TH |
89 | /** |
90 | * idr_preload_end - end preload section started with idr_preload() | |
91 | * | |
92 | * Each idr_preload() should be matched with an invocation of this | |
93 | * function. See idr_preload() for details. | |
94 | */ | |
95 | static inline void idr_preload_end(void) | |
96 | { | |
97 | preempt_enable(); | |
98 | } | |
99 | ||
0ffc2a9c TH |
100 | /** |
101 | * idr_find - return pointer for given id | |
5857f70c | 102 | * @idr: idr handle |
0ffc2a9c TH |
103 | * @id: lookup key |
104 | * | |
105 | * Return the pointer given the id it has been registered with. A %NULL | |
106 | * return indicates that @id is not valid or you passed %NULL in | |
107 | * idr_get_new(). | |
108 | * | |
109 | * This function can be called under rcu_read_lock(), given that the leaf | |
110 | * pointers lifetimes are correctly managed. | |
111 | */ | |
112 | static inline void *idr_find(struct idr *idr, int id) | |
113 | { | |
114 | struct idr_layer *hint = rcu_dereference_raw(idr->hint); | |
115 | ||
116 | if (hint && (id & ~IDR_MASK) == hint->prefix) | |
117 | return rcu_dereference_raw(hint->ary[id & IDR_MASK]); | |
118 | ||
119 | return idr_find_slowpath(idr, id); | |
120 | } | |
121 | ||
49038ef4 TH |
122 | /** |
123 | * idr_for_each_entry - iterate over an idr's elements of a given type | |
124 | * @idp: idr handle | |
125 | * @entry: the type * to use as cursor | |
126 | * @id: id entry's key | |
b949be58 GS |
127 | * |
128 | * @entry and @id do not need to be initialized before the loop, and | |
129 | * after normal terminatinon @entry is left with the value NULL. This | |
130 | * is convenient for a "not found" value. | |
49038ef4 | 131 | */ |
b949be58 GS |
132 | #define idr_for_each_entry(idp, entry, id) \ |
133 | for (id = 0; ((entry) = idr_get_next(idp, &(id))) != NULL; ++id) | |
49038ef4 | 134 | |
72dba584 TH |
135 | /* |
136 | * IDA - IDR based id allocator, use when translation from id to | |
137 | * pointer isn't necessary. | |
ed9f524a NK |
138 | * |
139 | * IDA_BITMAP_LONGS is calculated to be one less to accommodate | |
140 | * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes. | |
72dba584 TH |
141 | */ |
142 | #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ | |
ed9f524a NK |
143 | #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1) |
144 | #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) | |
72dba584 TH |
145 | |
146 | struct ida_bitmap { | |
147 | long nr_busy; | |
148 | unsigned long bitmap[IDA_BITMAP_LONGS]; | |
149 | }; | |
150 | ||
151 | struct ida { | |
152 | struct idr idr; | |
153 | struct ida_bitmap *free_bitmap; | |
154 | }; | |
155 | ||
eece09ec | 156 | #define IDA_INIT(name) { .idr = IDR_INIT((name).idr), .free_bitmap = NULL, } |
72dba584 TH |
157 | #define DEFINE_IDA(name) struct ida name = IDA_INIT(name) |
158 | ||
159 | int ida_pre_get(struct ida *ida, gfp_t gfp_mask); | |
160 | int ida_get_new_above(struct ida *ida, int starting_id, int *p_id); | |
72dba584 TH |
161 | void ida_remove(struct ida *ida, int id); |
162 | void ida_destroy(struct ida *ida); | |
163 | void ida_init(struct ida *ida); | |
164 | ||
88eca020 RR |
165 | int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, |
166 | gfp_t gfp_mask); | |
167 | void ida_simple_remove(struct ida *ida, unsigned int id); | |
168 | ||
9749f30f | 169 | /** |
49038ef4 TH |
170 | * ida_get_new - allocate new ID |
171 | * @ida: idr handle | |
172 | * @p_id: pointer to the allocated handle | |
173 | * | |
174 | * Simple wrapper around ida_get_new_above() w/ @starting_id of zero. | |
9749f30f | 175 | */ |
49038ef4 TH |
176 | static inline int ida_get_new(struct ida *ida, int *p_id) |
177 | { | |
178 | return ida_get_new_above(ida, 0, p_id); | |
179 | } | |
180 | ||
181 | void __init idr_init_cache(void); | |
9749f30f | 182 | |
f668ab1a | 183 | #endif /* __IDR_H__ */ |