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>
19 struct radix_tree_root idr_rt;
20 unsigned int idr_next;
24 * The IDR API does not expose the tagging functionality of the radix tree
25 * to users. Use tag 0 to track whether a node has free space below it.
29 /* Set the IDR flag and the IDR_FREE tag */
30 #define IDR_RT_MARKER ((__force gfp_t)(3 << __GFP_BITS_SHIFT))
34 .idr_rt = RADIX_TREE_INIT(IDR_RT_MARKER) \
36 #define DEFINE_IDR(name) struct idr name = IDR_INIT
39 * idr_get_cursor - Return the current position of the cyclic allocator
42 * The value returned is the value that will be next returned from
43 * idr_alloc_cyclic() if it is free (otherwise the search will start from
46 static inline unsigned int idr_get_cursor(const struct idr *idr)
48 return READ_ONCE(idr->idr_next);
52 * idr_set_cursor - Set the current position of the cyclic allocator
56 * The next call to idr_alloc_cyclic() will return @val if it is free
57 * (otherwise the search will start from this position).
59 static inline void idr_set_cursor(struct idr *idr, unsigned int val)
61 WRITE_ONCE(idr->idr_next, val);
66 * idr synchronization (stolen from radix-tree.h)
68 * idr_find() is able to be called locklessly, using RCU. The caller must
69 * ensure calls to this function are made within rcu_read_lock() regions.
70 * Other readers (lock-free or otherwise) and modifications may be running
73 * It is still required that the caller manage the synchronization and
74 * lifetimes of the items. So if RCU lock-free lookups are used, typically
75 * this would mean that the items have their own locks, or are amenable to
76 * lock-free access; and that the items are freed by RCU (or only freed after
77 * having been deleted from the idr tree *and* a synchronize_rcu() grace
81 void idr_preload(gfp_t gfp_mask);
82 int idr_alloc(struct idr *, void *entry, int start, int end, gfp_t);
83 int idr_alloc_cyclic(struct idr *, void *entry, int start, int end, gfp_t);
84 int idr_for_each(const struct idr *,
85 int (*fn)(int id, void *p, void *data), void *data);
86 void *idr_get_next(struct idr *, int *nextid);
87 void *idr_replace(struct idr *, void *, int id);
88 void idr_destroy(struct idr *);
90 static inline void idr_remove(struct idr *idr, int id)
92 radix_tree_delete(&idr->idr_rt, id);
95 static inline void idr_init(struct idr *idr)
97 INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER);
101 static inline bool idr_is_empty(const struct idr *idr)
103 return radix_tree_empty(&idr->idr_rt) &&
104 radix_tree_tagged(&idr->idr_rt, IDR_FREE);
108 * idr_preload_end - end preload section started with idr_preload()
110 * Each idr_preload() should be matched with an invocation of this
111 * function. See idr_preload() for details.
113 static inline void idr_preload_end(void)
119 * idr_find - return pointer for given id
123 * Return the pointer given the id it has been registered with. A %NULL
124 * return indicates that @id is not valid or you passed %NULL in
127 * This function can be called under rcu_read_lock(), given that the leaf
128 * pointers lifetimes are correctly managed.
130 static inline void *idr_find(const struct idr *idr, int id)
132 return radix_tree_lookup(&idr->idr_rt, id);
136 * idr_for_each_entry - iterate over an idr's elements of a given type
138 * @entry: the type * to use as cursor
139 * @id: id entry's key
141 * @entry and @id do not need to be initialized before the loop, and
142 * after normal terminatinon @entry is left with the value NULL. This
143 * is convenient for a "not found" value.
145 #define idr_for_each_entry(idr, entry, id) \
146 for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; ++id)
149 * idr_for_each_entry_continue - continue iteration over an idr's elements of a given type
151 * @entry: the type * to use as cursor
152 * @id: id entry's key
154 * Continue to iterate over list of given type, continuing after
155 * the current position.
157 #define idr_for_each_entry_continue(idr, entry, id) \
158 for ((entry) = idr_get_next((idr), &(id)); \
160 ++id, (entry) = idr_get_next((idr), &(id)))
163 * IDA - IDR based id allocator, use when translation from id to
164 * pointer isn't necessary.
166 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
167 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long))
168 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
171 unsigned long bitmap[IDA_BITMAP_LONGS];
175 struct radix_tree_root ida_rt;
176 struct ida_bitmap *free_bitmap;
180 .ida_rt = RADIX_TREE_INIT(IDR_RT_MARKER | GFP_NOWAIT), \
182 #define DEFINE_IDA(name) struct ida name = IDA_INIT
184 int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
185 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
186 void ida_remove(struct ida *ida, int id);
187 void ida_destroy(struct ida *ida);
189 int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
191 void ida_simple_remove(struct ida *ida, unsigned int id);
193 static inline void ida_init(struct ida *ida)
195 INIT_RADIX_TREE(&ida->ida_rt, IDR_RT_MARKER | GFP_NOWAIT);
196 ida->free_bitmap = NULL;
200 * ida_get_new - allocate new ID
202 * @p_id: pointer to the allocated handle
204 * Simple wrapper around ida_get_new_above() w/ @starting_id of zero.
206 static inline int ida_get_new(struct ida *ida, int *p_id)
208 return ida_get_new_above(ida, 0, p_id);
211 static inline bool ida_is_empty(const struct ida *ida)
213 return radix_tree_empty(&ida->ida_rt);
215 #endif /* __IDR_H__ */