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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 */
Luben Tuikovf668ab12005-11-08 17:14:08 +010011
12#ifndef __IDR_H__
13#define __IDR_H__
14
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/types.h>
16#include <linux/bitops.h>
Akinobu Mita199f0ca2008-04-29 01:03:13 -070017#include <linux/init.h>
Nadia Derbey2027d1a2008-07-25 01:47:57 -070018#include <linux/rcupdate.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019
Tejun Heo050a6b42013-02-27 17:05:06 -080020/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#define IDR_SIZE (1 << IDR_BITS)
28#define IDR_MASK ((1 << IDR_BITS)-1)
29
Linus Torvalds1da177e2005-04-16 15:20:36 -070030struct idr_layer {
Tejun Heo54616282013-02-27 17:05:07 -080031 int prefix; /* the ID prefix of this idr_layer */
Lai Jiangshandcbff5d2014-06-06 14:37:15 -070032 int layer; /* distance from leaf */
Arnd Bergmannd2c24862010-02-26 14:53:26 +010033 struct idr_layer __rcu *ary[1<<IDR_BITS];
Tejun Heo4106eca2013-02-27 17:03:51 -080034 int count; /* When zero, we can release it */
Lai Jiangshandcbff5d2014-06-06 14:37:15 -070035 union {
36 /* A zero bit means "space here" */
37 DECLARE_BITMAP(bitmap, IDR_SIZE);
38 struct rcu_head rcu_head;
39 };
Linus Torvalds1da177e2005-04-16 15:20:36 -070040};
41
42struct idr {
Tejun Heo0ffc2a92013-02-27 17:05:08 -080043 struct idr_layer __rcu *hint; /* the last layer allocated from */
Tejun Heo4106eca2013-02-27 17:03:51 -080044 struct idr_layer __rcu *top;
Tejun Heo4106eca2013-02-27 17:03:51 -080045 int layers; /* only valid w/o concurrent changes */
Jeff Layton3e6628c42013-04-29 16:21:16 -070046 int cur; /* current pos for cyclic allocation */
Tejun Heo4106eca2013-02-27 17:03:51 -080047 spinlock_t lock;
Lai Jiangshandcbff5d2014-06-06 14:37:15 -070048 int id_free_cnt;
49 struct idr_layer *id_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -070050};
51
Tejun Heo4106eca2013-02-27 17:03:51 -080052#define IDR_INIT(name) \
53{ \
54 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
Linus Torvalds1da177e2005-04-16 15:20:36 -070055}
56#define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
57
Nadia Derbeyf9c46d62008-07-25 01:48:01 -070058/**
Randy Dunlap56083ab2010-10-26 14:19:08 -070059 * DOC: idr sync
Nadia Derbeyf9c46d62008-07-25 01:48:01 -070060 * idr synchronization (stolen from radix-tree.h)
61 *
62 * idr_find() is able to be called locklessly, using RCU. The caller must
63 * ensure calls to this function are made within rcu_read_lock() regions.
64 * Other readers (lock-free or otherwise) and modifications may be running
65 * concurrently.
66 *
67 * It is still required that the caller manage the synchronization and
68 * lifetimes of the items. So if RCU lock-free lookups are used, typically
69 * this would mean that the items have their own locks, or are amenable to
70 * lock-free access; and that the items are freed by RCU (or only freed after
71 * having been deleted from the idr tree *and* a synchronize_rcu() grace
72 * period).
73 */
74
Linus Torvalds1da177e2005-04-16 15:20:36 -070075/*
76 * This is what we export.
77 */
78
Tejun Heo0ffc2a92013-02-27 17:05:08 -080079void *idr_find_slowpath(struct idr *idp, int id);
Tejun Heod5c74092013-02-27 17:03:55 -080080void idr_preload(gfp_t gfp_mask);
81int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask);
Jeff Layton3e6628c42013-04-29 16:21:16 -070082int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -070083int idr_for_each(struct idr *idp,
84 int (*fn)(int id, void *p, void *data), void *data);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -070085void *idr_get_next(struct idr *idp, int *nextid);
Jeff Mahoney5806f072006-06-26 00:27:19 -070086void *idr_replace(struct idr *idp, void *ptr, int id);
Linus Torvalds1da177e2005-04-16 15:20:36 -070087void idr_remove(struct idr *idp, int id);
Andrew Morton8d3b3592005-10-23 12:57:18 -070088void idr_destroy(struct idr *idp);
Linus Torvalds1da177e2005-04-16 15:20:36 -070089void idr_init(struct idr *idp);
Andreas Gruenbacher05f7a7d2011-08-08 23:36:56 +020090bool idr_is_empty(struct idr *idp);
Luben Tuikovf668ab12005-11-08 17:14:08 +010091
Tejun Heo49038ef2013-02-27 17:03:52 -080092/**
Tejun Heod5c74092013-02-27 17:03:55 -080093 * idr_preload_end - end preload section started with idr_preload()
94 *
95 * Each idr_preload() should be matched with an invocation of this
96 * function. See idr_preload() for details.
97 */
98static inline void idr_preload_end(void)
99{
100 preempt_enable();
101}
102
103/**
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800104 * idr_find - return pointer for given id
Randy Dunlap5857f702013-03-04 14:32:54 -0800105 * @idr: idr handle
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800106 * @id: lookup key
107 *
108 * Return the pointer given the id it has been registered with. A %NULL
109 * return indicates that @id is not valid or you passed %NULL in
110 * idr_get_new().
111 *
112 * This function can be called under rcu_read_lock(), given that the leaf
113 * pointers lifetimes are correctly managed.
114 */
115static inline void *idr_find(struct idr *idr, int id)
116{
117 struct idr_layer *hint = rcu_dereference_raw(idr->hint);
118
119 if (hint && (id & ~IDR_MASK) == hint->prefix)
120 return rcu_dereference_raw(hint->ary[id & IDR_MASK]);
121
122 return idr_find_slowpath(idr, id);
123}
124
125/**
Tejun Heo49038ef2013-02-27 17:03:52 -0800126 * idr_for_each_entry - iterate over an idr's elements of a given type
127 * @idp: idr handle
128 * @entry: the type * to use as cursor
129 * @id: id entry's key
George Spelvinb949be52013-03-27 14:08:33 +0100130 *
131 * @entry and @id do not need to be initialized before the loop, and
132 * after normal terminatinon @entry is left with the value NULL. This
133 * is convenient for a "not found" value.
Tejun Heo49038ef2013-02-27 17:03:52 -0800134 */
George Spelvinb949be52013-03-27 14:08:33 +0100135#define idr_for_each_entry(idp, entry, id) \
136 for (id = 0; ((entry) = idr_get_next(idp, &(id))) != NULL; ++id)
Tejun Heo49038ef2013-02-27 17:03:52 -0800137
Tejun Heoc8615d32013-03-13 14:59:42 -0700138/*
Tejun Heo72dba582007-06-14 03:45:13 +0900139 * IDA - IDR based id allocator, use when translation from id to
140 * pointer isn't necessary.
Namhyung Kimed9f5242010-09-16 01:30:19 +0900141 *
142 * IDA_BITMAP_LONGS is calculated to be one less to accommodate
143 * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes.
Tejun Heo72dba582007-06-14 03:45:13 +0900144 */
145#define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
Namhyung Kimed9f5242010-09-16 01:30:19 +0900146#define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1)
147#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
Tejun Heo72dba582007-06-14 03:45:13 +0900148
149struct ida_bitmap {
150 long nr_busy;
151 unsigned long bitmap[IDA_BITMAP_LONGS];
152};
153
154struct ida {
155 struct idr idr;
156 struct ida_bitmap *free_bitmap;
157};
158
Thomas Gleixnereece09e2011-07-17 21:25:03 +0200159#define IDA_INIT(name) { .idr = IDR_INIT((name).idr), .free_bitmap = NULL, }
Tejun Heo72dba582007-06-14 03:45:13 +0900160#define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
161
162int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
163int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
Tejun Heo72dba582007-06-14 03:45:13 +0900164void ida_remove(struct ida *ida, int id);
165void ida_destroy(struct ida *ida);
166void ida_init(struct ida *ida);
167
Rusty Russell88eca022011-08-03 16:21:06 -0700168int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
169 gfp_t gfp_mask);
170void ida_simple_remove(struct ida *ida, unsigned int id);
171
Philipp Reisner9749f302011-07-20 14:59:37 +0200172/**
Tejun Heo49038ef2013-02-27 17:03:52 -0800173 * ida_get_new - allocate new ID
174 * @ida: idr handle
175 * @p_id: pointer to the allocated handle
176 *
177 * Simple wrapper around ida_get_new_above() w/ @starting_id of zero.
Philipp Reisner9749f302011-07-20 14:59:37 +0200178 */
Tejun Heo49038ef2013-02-27 17:03:52 -0800179static inline int ida_get_new(struct ida *ida, int *p_id)
180{
181 return ida_get_new_above(ida, 0, p_id);
182}
183
184void __init idr_init_cache(void);
Philipp Reisner9749f302011-07-20 14:59:37 +0200185
Luben Tuikovf668ab12005-11-08 17:14:08 +0100186#endif /* __IDR_H__ */