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_base; 22 unsigned int idr_next; 23 }; 24 25 /* 26 * The IDR API does not expose the tagging functionality of the radix tree 27 * to users. Use tag 0 to track whether a node has free space below it. 28 */ 29 #define IDR_FREE 0 30 31 /* Set the IDR flag and the IDR_FREE tag */ 32 #define IDR_RT_MARKER (ROOT_IS_IDR | (__force gfp_t) \ 33 (1 << (ROOT_TAG_SHIFT + IDR_FREE))) 34 35 #define IDR_INIT_BASE(name, base) { \ 36 .idr_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER), \ 37 .idr_base = (base), \ 38 .idr_next = 0, \ 39 } 40 41 /** 42 * IDR_INIT() - Initialise an IDR. 43 * @name: Name of IDR. 44 * 45 * A freshly-initialised IDR contains no IDs. 46 */ 47 #define IDR_INIT(name) IDR_INIT_BASE(name, 0) 48 49 /** 50 * DEFINE_IDR() - Define a statically-allocated IDR. 51 * @name: Name of IDR. 52 * 53 * An IDR defined using this macro is ready for use with no additional 54 * initialisation required. It contains no IDs. 55 */ 56 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name) 57 58 /** 59 * idr_get_cursor - Return the current position of the cyclic allocator 60 * @idr: idr handle 61 * 62 * The value returned is the value that will be next returned from 63 * idr_alloc_cyclic() if it is free (otherwise the search will start from 64 * this position). 65 */ 66 static inline unsigned int idr_get_cursor(const struct idr *idr) 67 { 68 return READ_ONCE(idr->idr_next); 69 } 70 71 /** 72 * idr_set_cursor - Set the current position of the cyclic allocator 73 * @idr: idr handle 74 * @val: new position 75 * 76 * The next call to idr_alloc_cyclic() will return @val if it is free 77 * (otherwise the search will start from this position). 78 */ 79 static inline void idr_set_cursor(struct idr *idr, unsigned int val) 80 { 81 WRITE_ONCE(idr->idr_next, val); 82 } 83 84 /** 85 * DOC: idr sync 86 * idr synchronization (stolen from radix-tree.h) 87 * 88 * idr_find() is able to be called locklessly, using RCU. The caller must 89 * ensure calls to this function are made within rcu_read_lock() regions. 90 * Other readers (lock-free or otherwise) and modifications may be running 91 * concurrently. 92 * 93 * It is still required that the caller manage the synchronization and 94 * lifetimes of the items. So if RCU lock-free lookups are used, typically 95 * this would mean that the items have their own locks, or are amenable to 96 * lock-free access; and that the items are freed by RCU (or only freed after 97 * having been deleted from the idr tree *and* a synchronize_rcu() grace 98 * period). 99 */ 100 101 void idr_preload(gfp_t gfp_mask); 102 103 int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t); 104 int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id, 105 unsigned long max, gfp_t); 106 int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t); 107 void *idr_remove(struct idr *, unsigned long id); 108 void *idr_find(const struct idr *, unsigned long id); 109 int idr_for_each(const struct idr *, 110 int (*fn)(int id, void *p, void *data), void *data); 111 void *idr_get_next(struct idr *, int *nextid); 112 void *idr_get_next_ul(struct idr *, unsigned long *nextid); 113 void *idr_replace(struct idr *, void *, unsigned long id); 114 void idr_destroy(struct idr *); 115 116 /** 117 * idr_init_base() - Initialise an IDR. 118 * @idr: IDR handle. 119 * @base: The base value for the IDR. 120 * 121 * This variation of idr_init() creates an IDR which will allocate IDs 122 * starting at %base. 123 */ 124 static inline void idr_init_base(struct idr *idr, int base) 125 { 126 INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER); 127 idr->idr_base = base; 128 idr->idr_next = 0; 129 } 130 131 /** 132 * idr_init() - Initialise an IDR. 133 * @idr: IDR handle. 134 * 135 * Initialise a dynamically allocated IDR. To initialise a 136 * statically allocated IDR, use DEFINE_IDR(). 137 */ 138 static inline void idr_init(struct idr *idr) 139 { 140 idr_init_base(idr, 0); 141 } 142 143 /** 144 * idr_is_empty() - Are there any IDs allocated? 145 * @idr: IDR handle. 146 * 147 * Return: %true if any IDs have been allocated from this IDR. 148 */ 149 static inline bool idr_is_empty(const struct idr *idr) 150 { 151 return radix_tree_empty(&idr->idr_rt) && 152 radix_tree_tagged(&idr->idr_rt, IDR_FREE); 153 } 154 155 /** 156 * idr_preload_end - end preload section started with idr_preload() 157 * 158 * Each idr_preload() should be matched with an invocation of this 159 * function. See idr_preload() for details. 160 */ 161 static inline void idr_preload_end(void) 162 { 163 preempt_enable(); 164 } 165 166 /** 167 * idr_for_each_entry() - Iterate over an IDR's elements of a given type. 168 * @idr: IDR handle. 169 * @entry: The type * to use as cursor 170 * @id: Entry ID. 171 * 172 * @entry and @id do not need to be initialized before the loop, and 173 * after normal termination @entry is left with the value NULL. This 174 * is convenient for a "not found" value. 175 */ 176 #define idr_for_each_entry(idr, entry, id) \ 177 for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; ++id) 178 179 /** 180 * idr_for_each_entry_ul() - Iterate over an IDR's elements of a given type. 181 * @idr: IDR handle. 182 * @entry: The type * to use as cursor. 183 * @id: Entry ID. 184 * 185 * @entry and @id do not need to be initialized before the loop, and 186 * after normal termination @entry is left with the value NULL. This 187 * is convenient for a "not found" value. 188 */ 189 #define idr_for_each_entry_ul(idr, entry, id) \ 190 for (id = 0; ((entry) = idr_get_next_ul(idr, &(id))) != NULL; ++id) 191 192 /** 193 * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type 194 * @idr: IDR handle. 195 * @entry: The type * to use as a cursor. 196 * @id: Entry ID. 197 * 198 * Continue to iterate over entries, continuing after the current position. 199 */ 200 #define idr_for_each_entry_continue(idr, entry, id) \ 201 for ((entry) = idr_get_next((idr), &(id)); \ 202 entry; \ 203 ++id, (entry) = idr_get_next((idr), &(id))) 204 205 /* 206 * IDA - IDR based id allocator, use when translation from id to 207 * pointer isn't necessary. 208 */ 209 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ 210 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long)) 211 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) 212 213 struct ida_bitmap { 214 unsigned long bitmap[IDA_BITMAP_LONGS]; 215 }; 216 217 DECLARE_PER_CPU(struct ida_bitmap *, ida_bitmap); 218 219 struct ida { 220 struct radix_tree_root ida_rt; 221 }; 222 223 #define IDA_INIT(name) { \ 224 .ida_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER | GFP_NOWAIT), \ 225 } 226 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name) 227 228 int ida_pre_get(struct ida *ida, gfp_t gfp_mask); 229 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id); 230 void ida_remove(struct ida *ida, int id); 231 void ida_destroy(struct ida *ida); 232 233 int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, 234 gfp_t gfp_mask); 235 void ida_simple_remove(struct ida *ida, unsigned int id); 236 237 static inline void ida_init(struct ida *ida) 238 { 239 INIT_RADIX_TREE(&ida->ida_rt, IDR_RT_MARKER | GFP_NOWAIT); 240 } 241 242 /** 243 * ida_get_new - allocate new ID 244 * @ida: idr handle 245 * @p_id: pointer to the allocated handle 246 * 247 * Simple wrapper around ida_get_new_above() w/ @starting_id of zero. 248 */ 249 static inline int ida_get_new(struct ida *ida, int *p_id) 250 { 251 return ida_get_new_above(ida, 0, p_id); 252 } 253 254 static inline bool ida_is_empty(const struct ida *ida) 255 { 256 return radix_tree_empty(&ida->ida_rt); 257 } 258 #endif /* __IDR_H__ */ 259