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git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - include/linux/idr.h
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.
8 * Small id to pointer translation service avoiding fixed sized
15 #include <linux/radix-tree.h>
16 #include <linux/gfp.h>
17 #include <linux/percpu.h>
20 struct radix_tree_root idr_rt
;
21 unsigned int idr_next
;
25 * The IDR API does not expose the tagging functionality of the radix tree
26 * to users. Use tag 0 to track whether a node has free space below it.
30 /* Set the IDR flag and the IDR_FREE tag */
31 #define IDR_RT_MARKER ((__force gfp_t)(3 << __GFP_BITS_SHIFT))
35 .idr_rt = RADIX_TREE_INIT(IDR_RT_MARKER) \
37 #define DEFINE_IDR(name) struct idr name = IDR_INIT
40 * idr_get_cursor - Return the current position of the cyclic allocator
43 * The value returned is the value that will be next returned from
44 * idr_alloc_cyclic() if it is free (otherwise the search will start from
47 static inline unsigned int idr_get_cursor(const struct idr
*idr
)
49 return READ_ONCE(idr
->idr_next
);
53 * idr_set_cursor - Set the current position of the cyclic allocator
57 * The next call to idr_alloc_cyclic() will return @val if it is free
58 * (otherwise the search will start from this position).
60 static inline void idr_set_cursor(struct idr
*idr
, unsigned int val
)
62 WRITE_ONCE(idr
->idr_next
, val
);
67 * idr synchronization (stolen from radix-tree.h)
69 * idr_find() is able to be called locklessly, using RCU. The caller must
70 * ensure calls to this function are made within rcu_read_lock() regions.
71 * Other readers (lock-free or otherwise) and modifications may be running
74 * It is still required that the caller manage the synchronization and
75 * lifetimes of the items. So if RCU lock-free lookups are used, typically
76 * this would mean that the items have their own locks, or are amenable to
77 * lock-free access; and that the items are freed by RCU (or only freed after
78 * having been deleted from the idr tree *and* a synchronize_rcu() grace
82 void idr_preload(gfp_t gfp_mask
);
84 int idr_alloc_cmn(struct idr
*idr
, void *ptr
, unsigned long *index
,
85 unsigned long start
, unsigned long end
, gfp_t gfp
,
89 * idr_alloc - allocate an id
91 * @ptr: pointer to be associated with the new id
92 * @start: the minimum id (inclusive)
93 * @end: the maximum id (exclusive)
94 * @gfp: memory allocation flags
96 * Allocates an unused ID in the range [start, end). Returns -ENOSPC
97 * if there are no unused IDs in that range.
99 * Note that @end is treated as max when <= 0. This is to always allow
100 * using @start + N as @end as long as N is inside integer range.
102 * Simultaneous modifications to the @idr are not allowed and should be
103 * prevented by the user, usually with a lock. idr_alloc() may be called
104 * concurrently with read-only accesses to the @idr, such as idr_find() and
105 * idr_for_each_entry().
107 static inline int idr_alloc(struct idr
*idr
, void *ptr
,
108 int start
, int end
, gfp_t gfp
)
113 if (WARN_ON_ONCE(start
< 0))
116 ret
= idr_alloc_cmn(idr
, ptr
, &id
, start
, end
, gfp
, false);
124 static inline int idr_alloc_ext(struct idr
*idr
, void *ptr
,
125 unsigned long *index
,
130 return idr_alloc_cmn(idr
, ptr
, index
, start
, end
, gfp
, true);
133 int idr_alloc_cyclic(struct idr
*, void *entry
, int start
, int end
, gfp_t
);
134 int idr_for_each(const struct idr
*,
135 int (*fn
)(int id
, void *p
, void *data
), void *data
);
136 void *idr_get_next(struct idr
*, int *nextid
);
137 void *idr_get_next_ext(struct idr
*idr
, unsigned long *nextid
);
138 void *idr_replace(struct idr
*, void *, int id
);
139 void *idr_replace_ext(struct idr
*idr
, void *ptr
, unsigned long id
);
140 void idr_destroy(struct idr
*);
142 static inline void *idr_remove_ext(struct idr
*idr
, unsigned long id
)
144 return radix_tree_delete_item(&idr
->idr_rt
, id
, NULL
);
147 static inline void *idr_remove(struct idr
*idr
, int id
)
149 return idr_remove_ext(idr
, id
);
152 static inline void idr_init(struct idr
*idr
)
154 INIT_RADIX_TREE(&idr
->idr_rt
, IDR_RT_MARKER
);
158 static inline bool idr_is_empty(const struct idr
*idr
)
160 return radix_tree_empty(&idr
->idr_rt
) &&
161 radix_tree_tagged(&idr
->idr_rt
, IDR_FREE
);
165 * idr_preload_end - end preload section started with idr_preload()
167 * Each idr_preload() should be matched with an invocation of this
168 * function. See idr_preload() for details.
170 static inline void idr_preload_end(void)
176 * idr_find - return pointer for given id
180 * Return the pointer given the id it has been registered with. A %NULL
181 * return indicates that @id is not valid or you passed %NULL in
184 * This function can be called under rcu_read_lock(), given that the leaf
185 * pointers lifetimes are correctly managed.
187 static inline void *idr_find_ext(const struct idr
*idr
, unsigned long id
)
189 return radix_tree_lookup(&idr
->idr_rt
, id
);
192 static inline void *idr_find(const struct idr
*idr
, int id
)
194 return idr_find_ext(idr
, id
);
198 * idr_for_each_entry - iterate over an idr's elements of a given type
200 * @entry: the type * to use as cursor
201 * @id: id entry's key
203 * @entry and @id do not need to be initialized before the loop, and
204 * after normal terminatinon @entry is left with the value NULL. This
205 * is convenient for a "not found" value.
207 #define idr_for_each_entry(idr, entry, id) \
208 for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; ++id)
209 #define idr_for_each_entry_ext(idr, entry, id) \
210 for (id = 0; ((entry) = idr_get_next_ext(idr, &(id))) != NULL; ++id)
213 * idr_for_each_entry_continue - continue iteration over an idr's elements of a given type
215 * @entry: the type * to use as cursor
216 * @id: id entry's key
218 * Continue to iterate over list of given type, continuing after
219 * the current position.
221 #define idr_for_each_entry_continue(idr, entry, id) \
222 for ((entry) = idr_get_next((idr), &(id)); \
224 ++id, (entry) = idr_get_next((idr), &(id)))
227 * IDA - IDR based id allocator, use when translation from id to
228 * pointer isn't necessary.
230 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
231 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long))
232 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
235 unsigned long bitmap
[IDA_BITMAP_LONGS
];
238 DECLARE_PER_CPU(struct ida_bitmap
*, ida_bitmap
);
241 struct radix_tree_root ida_rt
;
245 .ida_rt = RADIX_TREE_INIT(IDR_RT_MARKER | GFP_NOWAIT), \
247 #define DEFINE_IDA(name) struct ida name = IDA_INIT
249 int ida_pre_get(struct ida
*ida
, gfp_t gfp_mask
);
250 int ida_get_new_above(struct ida
*ida
, int starting_id
, int *p_id
);
251 void ida_remove(struct ida
*ida
, int id
);
252 void ida_destroy(struct ida
*ida
);
254 int ida_simple_get(struct ida
*ida
, unsigned int start
, unsigned int end
,
256 void ida_simple_remove(struct ida
*ida
, unsigned int id
);
258 static inline void ida_init(struct ida
*ida
)
260 INIT_RADIX_TREE(&ida
->ida_rt
, IDR_RT_MARKER
| GFP_NOWAIT
);
264 * ida_get_new - allocate new ID
266 * @p_id: pointer to the allocated handle
268 * Simple wrapper around ida_get_new_above() w/ @starting_id of zero.
270 static inline int ida_get_new(struct ida
*ida
, int *p_id
)
272 return ida_get_new_above(ida
, 0, p_id
);
275 static inline bool ida_is_empty(const struct ida
*ida
)
277 return radix_tree_empty(&ida
->ida_rt
);
279 #endif /* __IDR_H__ */