1 /* 2 * include/linux/idr.h 3 * 4 * 2002-10-18 written by Jim Houston [email protected] 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 */ 11 12 #ifndef __IDR_H__ 13 #define __IDR_H__ 14 15 #include <linux/radix-tree.h> 16 #include <linux/gfp.h> 17 #include <linux/percpu.h> 18 19 struct idr { 20 struct radix_tree_root idr_rt; 21 unsigned int idr_next; 22 }; 23 24 /* 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. 27 */ 28 #define IDR_FREE 0 29 30 /* Set the IDR flag and the IDR_FREE tag */ 31 #define IDR_RT_MARKER ((__force gfp_t)(3 << __GFP_BITS_SHIFT)) 32 33 #define IDR_INIT \ 34 { \ 35 .idr_rt = RADIX_TREE_INIT(IDR_RT_MARKER) \ 36 } 37 #define DEFINE_IDR(name) struct idr name = IDR_INIT 38 39 /** 40 * idr_get_cursor - Return the current position of the cyclic allocator 41 * @idr: idr handle 42 * 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 45 * this position). 46 */ 47 static inline unsigned int idr_get_cursor(const struct idr *idr) 48 { 49 return READ_ONCE(idr->idr_next); 50 } 51 52 /** 53 * idr_set_cursor - Set the current position of the cyclic allocator 54 * @idr: idr handle 55 * @val: new position 56 * 57 * The next call to idr_alloc_cyclic() will return @val if it is free 58 * (otherwise the search will start from this position). 59 */ 60 static inline void idr_set_cursor(struct idr *idr, unsigned int val) 61 { 62 WRITE_ONCE(idr->idr_next, val); 63 } 64 65 /** 66 * DOC: idr sync 67 * idr synchronization (stolen from radix-tree.h) 68 * 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 72 * concurrently. 73 * 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 79 * period). 80 */ 81 82 void idr_preload(gfp_t gfp_mask); 83 int idr_alloc(struct idr *, void *entry, int start, int end, gfp_t); 84 int idr_alloc_cyclic(struct idr *, void *entry, int start, int end, gfp_t); 85 int idr_for_each(const struct idr *, 86 int (*fn)(int id, void *p, void *data), void *data); 87 void *idr_get_next(struct idr *, int *nextid); 88 void *idr_replace(struct idr *, void *, int id); 89 void idr_destroy(struct idr *); 90 91 static inline void *idr_remove(struct idr *idr, int id) 92 { 93 return radix_tree_delete_item(&idr->idr_rt, id, NULL); 94 } 95 96 static inline void idr_init(struct idr *idr) 97 { 98 INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER); 99 idr->idr_next = 0; 100 } 101 102 static inline bool idr_is_empty(const struct idr *idr) 103 { 104 return radix_tree_empty(&idr->idr_rt) && 105 radix_tree_tagged(&idr->idr_rt, IDR_FREE); 106 } 107 108 /** 109 * idr_preload_end - end preload section started with idr_preload() 110 * 111 * Each idr_preload() should be matched with an invocation of this 112 * function. See idr_preload() for details. 113 */ 114 static inline void idr_preload_end(void) 115 { 116 preempt_enable(); 117 } 118 119 /** 120 * idr_find - return pointer for given id 121 * @idr: idr handle 122 * @id: lookup key 123 * 124 * Return the pointer given the id it has been registered with. A %NULL 125 * return indicates that @id is not valid or you passed %NULL in 126 * idr_get_new(). 127 * 128 * This function can be called under rcu_read_lock(), given that the leaf 129 * pointers lifetimes are correctly managed. 130 */ 131 static inline void *idr_find(const struct idr *idr, int id) 132 { 133 return radix_tree_lookup(&idr->idr_rt, id); 134 } 135 136 /** 137 * idr_for_each_entry - iterate over an idr's elements of a given type 138 * @idr: idr handle 139 * @entry: the type * to use as cursor 140 * @id: id entry's key 141 * 142 * @entry and @id do not need to be initialized before the loop, and 143 * after normal terminatinon @entry is left with the value NULL. This 144 * is convenient for a "not found" value. 145 */ 146 #define idr_for_each_entry(idr, entry, id) \ 147 for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; ++id) 148 149 /** 150 * idr_for_each_entry_continue - continue iteration over an idr's elements of a given type 151 * @idr: idr handle 152 * @entry: the type * to use as cursor 153 * @id: id entry's key 154 * 155 * Continue to iterate over list of given type, continuing after 156 * the current position. 157 */ 158 #define idr_for_each_entry_continue(idr, entry, id) \ 159 for ((entry) = idr_get_next((idr), &(id)); \ 160 entry; \ 161 ++id, (entry) = idr_get_next((idr), &(id))) 162 163 /* 164 * IDA - IDR based id allocator, use when translation from id to 165 * pointer isn't necessary. 166 */ 167 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ 168 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long)) 169 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) 170 171 struct ida_bitmap { 172 unsigned long bitmap[IDA_BITMAP_LONGS]; 173 }; 174 175 DECLARE_PER_CPU(struct ida_bitmap *, ida_bitmap); 176 177 struct ida { 178 struct radix_tree_root ida_rt; 179 }; 180 181 #define IDA_INIT { \ 182 .ida_rt = RADIX_TREE_INIT(IDR_RT_MARKER | GFP_NOWAIT), \ 183 } 184 #define DEFINE_IDA(name) struct ida name = IDA_INIT 185 186 int ida_pre_get(struct ida *ida, gfp_t gfp_mask); 187 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id); 188 void ida_remove(struct ida *ida, int id); 189 void ida_destroy(struct ida *ida); 190 191 int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, 192 gfp_t gfp_mask); 193 void ida_simple_remove(struct ida *ida, unsigned int id); 194 195 static inline void ida_init(struct ida *ida) 196 { 197 INIT_RADIX_TREE(&ida->ida_rt, IDR_RT_MARKER | GFP_NOWAIT); 198 } 199 200 /** 201 * ida_get_new - allocate new ID 202 * @ida: idr handle 203 * @p_id: pointer to the allocated handle 204 * 205 * Simple wrapper around ida_get_new_above() w/ @starting_id of zero. 206 */ 207 static inline int ida_get_new(struct ida *ida, int *p_id) 208 { 209 return ida_get_new_above(ida, 0, p_id); 210 } 211 212 static inline bool ida_is_empty(const struct ida *ida) 213 { 214 return radix_tree_empty(&ida->ida_rt); 215 } 216 #endif /* __IDR_H__ */ 217