1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * include/linux/idr.h 4 * 5 * 2002-10-18 written by Jim Houston jim.houston@ccur.com 6 * Copyright (C) 2002 by Concurrent Computer Corporation 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 #include <linux/cleanup.h> 19 #include <linux/compiler.h> 20 21 struct idr { 22 struct radix_tree_root idr_rt; 23 unsigned int idr_base; 24 unsigned int idr_next; 25 }; 26 27 /* 28 * The IDR API does not expose the tagging functionality of the radix tree 29 * to users. Use tag 0 to track whether a node has free space below it. 30 */ 31 #define IDR_FREE 0 32 33 /* Set the IDR flag and the IDR_FREE tag */ 34 #define IDR_RT_MARKER (ROOT_IS_IDR | (__force gfp_t) \ 35 (1 << (ROOT_TAG_SHIFT + IDR_FREE))) 36 37 #define IDR_INIT_BASE(name, base) { \ 38 .idr_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER), \ 39 .idr_base = (base), \ 40 .idr_next = 0, \ 41 } 42 43 /** 44 * IDR_INIT() - Initialise an IDR. 45 * @name: Name of IDR. 46 * 47 * A freshly-initialised IDR contains no IDs. 48 */ 49 #define IDR_INIT(name) IDR_INIT_BASE(name, 0) 50 51 /** 52 * DEFINE_IDR() - Define a statically-allocated IDR. 53 * @name: Name of IDR. 54 * 55 * An IDR defined using this macro is ready for use with no additional 56 * initialisation required. It contains no IDs. 57 */ 58 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name) 59 60 /** 61 * idr_get_cursor - Return the current position of the cyclic allocator 62 * @idr: idr handle 63 * 64 * The value returned is the value that will be next returned from 65 * idr_alloc_cyclic() if it is free (otherwise the search will start from 66 * this position). 67 */ 68 static inline unsigned int idr_get_cursor(const struct idr *idr) 69 { 70 return READ_ONCE(idr->idr_next); 71 } 72 73 /** 74 * idr_set_cursor - Set the current position of the cyclic allocator 75 * @idr: idr handle 76 * @val: new position 77 * 78 * The next call to idr_alloc_cyclic() will return @val if it is free 79 * (otherwise the search will start from this position). 80 */ 81 static inline void idr_set_cursor(struct idr *idr, unsigned int val) 82 { 83 WRITE_ONCE(idr->idr_next, val); 84 } 85 86 /** 87 * DOC: idr sync 88 * idr synchronization (stolen from radix-tree.h) 89 * 90 * idr_find() is able to be called locklessly, using RCU. The caller must 91 * ensure calls to this function are made within rcu_read_lock() regions. 92 * Other readers (lock-free or otherwise) and modifications may be running 93 * concurrently. 94 * 95 * It is still required that the caller manage the synchronization and 96 * lifetimes of the items. So if RCU lock-free lookups are used, typically 97 * this would mean that the items have their own locks, or are amenable to 98 * lock-free access; and that the items are freed by RCU (or only freed after 99 * having been deleted from the idr tree *and* a synchronize_rcu() grace 100 * period). 101 */ 102 103 #define idr_lock(idr) xa_lock(&(idr)->idr_rt) 104 #define idr_unlock(idr) xa_unlock(&(idr)->idr_rt) 105 #define idr_lock_bh(idr) xa_lock_bh(&(idr)->idr_rt) 106 #define idr_unlock_bh(idr) xa_unlock_bh(&(idr)->idr_rt) 107 #define idr_lock_irq(idr) xa_lock_irq(&(idr)->idr_rt) 108 #define idr_unlock_irq(idr) xa_unlock_irq(&(idr)->idr_rt) 109 #define idr_lock_irqsave(idr, flags) \ 110 xa_lock_irqsave(&(idr)->idr_rt, flags) 111 #define idr_unlock_irqrestore(idr, flags) \ 112 xa_unlock_irqrestore(&(idr)->idr_rt, flags) 113 114 void idr_preload(gfp_t gfp_mask); 115 116 int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t); 117 int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id, 118 unsigned long max, gfp_t); 119 int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t); 120 void *idr_remove(struct idr *, unsigned long id); 121 void *idr_find(const struct idr *, unsigned long id); 122 int idr_for_each(const struct idr *, 123 int (*fn)(int id, void *p, void *data), void *data); 124 void *idr_get_next(struct idr *, int *nextid); 125 void *idr_get_next_ul(struct idr *, unsigned long *nextid); 126 void *idr_replace(struct idr *, void *, unsigned long id); 127 void idr_destroy(struct idr *); 128 129 struct __class_idr { 130 struct idr *idr; 131 int id; 132 }; 133 134 #define idr_null ((struct __class_idr){ NULL, -1 }) 135 #define take_idr_id(id) __get_and_null(id, idr_null) 136 137 DEFINE_CLASS(idr_alloc, struct __class_idr, 138 if (_T.id >= 0) idr_remove(_T.idr, _T.id), 139 ((struct __class_idr){ 140 .idr = idr, 141 .id = idr_alloc(idr, ptr, start, end, gfp), 142 }), 143 struct idr *idr, void *ptr, int start, int end, gfp_t gfp); 144 145 /** 146 * idr_init_base() - Initialise an IDR. 147 * @idr: IDR handle. 148 * @base: The base value for the IDR. 149 * 150 * This variation of idr_init() creates an IDR which will allocate IDs 151 * starting at %base. 152 */ 153 static inline void idr_init_base(struct idr *idr, int base) 154 { 155 INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER); 156 idr->idr_base = base; 157 idr->idr_next = 0; 158 } 159 160 /** 161 * idr_init() - Initialise an IDR. 162 * @idr: IDR handle. 163 * 164 * Initialise a dynamically allocated IDR. To initialise a 165 * statically allocated IDR, use DEFINE_IDR(). 166 */ 167 static inline void idr_init(struct idr *idr) 168 { 169 idr_init_base(idr, 0); 170 } 171 172 /** 173 * idr_is_empty() - Are there any IDs allocated? 174 * @idr: IDR handle. 175 * 176 * Return: %true if any IDs have been allocated from this IDR. 177 */ 178 static inline bool idr_is_empty(const struct idr *idr) 179 { 180 return radix_tree_empty(&idr->idr_rt) && 181 radix_tree_tagged(&idr->idr_rt, IDR_FREE); 182 } 183 184 /** 185 * idr_preload_end - end preload section started with idr_preload() 186 * 187 * Each idr_preload() should be matched with an invocation of this 188 * function. See idr_preload() for details. 189 */ 190 static inline void idr_preload_end(void) 191 { 192 local_unlock(&radix_tree_preloads.lock); 193 } 194 195 /** 196 * idr_for_each_entry() - Iterate over an IDR's elements of a given type. 197 * @idr: IDR handle. 198 * @entry: The type * to use as cursor 199 * @id: Entry ID. 200 * 201 * @entry and @id do not need to be initialized before the loop, and 202 * after normal termination @entry is left with the value NULL. This 203 * is convenient for a "not found" value. 204 */ 205 #define idr_for_each_entry(idr, entry, id) \ 206 for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; id += 1U) 207 208 /** 209 * idr_for_each_entry_ul() - Iterate over an IDR's elements of a given type. 210 * @idr: IDR handle. 211 * @entry: The type * to use as cursor. 212 * @tmp: A temporary placeholder for ID. 213 * @id: Entry ID. 214 * 215 * @entry and @id do not need to be initialized before the loop, and 216 * after normal termination @entry is left with the value NULL. This 217 * is convenient for a "not found" value. 218 */ 219 #define idr_for_each_entry_ul(idr, entry, tmp, id) \ 220 for (tmp = 0, id = 0; \ 221 ((entry) = tmp <= id ? idr_get_next_ul(idr, &(id)) : NULL) != NULL; \ 222 tmp = id, ++id) 223 224 /** 225 * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type 226 * @idr: IDR handle. 227 * @entry: The type * to use as a cursor. 228 * @id: Entry ID. 229 * 230 * Continue to iterate over entries, continuing after the current position. 231 */ 232 #define idr_for_each_entry_continue(idr, entry, id) \ 233 for ((entry) = idr_get_next((idr), &(id)); \ 234 entry; \ 235 ++id, (entry) = idr_get_next((idr), &(id))) 236 237 /** 238 * idr_for_each_entry_continue_ul() - Continue iteration over an IDR's elements of a given type 239 * @idr: IDR handle. 240 * @entry: The type * to use as a cursor. 241 * @tmp: A temporary placeholder for ID. 242 * @id: Entry ID. 243 * 244 * Continue to iterate over entries, continuing after the current position. 245 * After normal termination @entry is left with the value NULL. This 246 * is convenient for a "not found" value. 247 */ 248 #define idr_for_each_entry_continue_ul(idr, entry, tmp, id) \ 249 for (tmp = id; \ 250 ((entry) = tmp <= id ? idr_get_next_ul(idr, &(id)) : NULL) != NULL; \ 251 tmp = id, ++id) 252 253 /* 254 * IDA - ID Allocator, use when translation from id to pointer isn't necessary. 255 */ 256 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ 257 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long)) 258 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) 259 260 struct ida_bitmap { 261 unsigned long bitmap[IDA_BITMAP_LONGS]; 262 }; 263 264 struct ida { 265 struct xarray xa; 266 }; 267 268 #define IDA_INIT_FLAGS (XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC) 269 270 #define IDA_INIT(name) { \ 271 .xa = XARRAY_INIT(name, IDA_INIT_FLAGS) \ 272 } 273 #define DEFINE_IDA(name) \ 274 struct ida name = IDA_INIT(name); \ 275 ASSERT_STATIC_STORAGE(name) 276 277 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t); 278 void ida_free(struct ida *, unsigned int id); 279 void ida_destroy(struct ida *ida); 280 int ida_find_first_range(struct ida *ida, unsigned int min, unsigned int max); 281 282 /** 283 * ida_alloc() - Allocate an unused ID. 284 * @ida: IDA handle. 285 * @gfp: Memory allocation flags. 286 * 287 * Allocate an ID between 0 and %INT_MAX, inclusive. 288 * 289 * Context: Any context. It is safe to call this function without 290 * locking in your code. 291 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated, 292 * or %-ENOSPC if there are no free IDs. 293 */ 294 static inline int ida_alloc(struct ida *ida, gfp_t gfp) 295 { 296 return ida_alloc_range(ida, 0, ~0, gfp); 297 } 298 299 /** 300 * ida_alloc_min() - Allocate an unused ID. 301 * @ida: IDA handle. 302 * @min: Lowest ID to allocate. 303 * @gfp: Memory allocation flags. 304 * 305 * Allocate an ID between @min and %INT_MAX, inclusive. 306 * 307 * Context: Any context. It is safe to call this function without 308 * locking in your code. 309 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated, 310 * or %-ENOSPC if there are no free IDs. 311 */ 312 static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp) 313 { 314 return ida_alloc_range(ida, min, ~0, gfp); 315 } 316 317 /** 318 * ida_alloc_max() - Allocate an unused ID. 319 * @ida: IDA handle. 320 * @max: Highest ID to allocate. 321 * @gfp: Memory allocation flags. 322 * 323 * Allocate an ID between 0 and @max, inclusive. 324 * 325 * Context: Any context. It is safe to call this function without 326 * locking in your code. 327 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated, 328 * or %-ENOSPC if there are no free IDs. 329 */ 330 static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp) 331 { 332 return ida_alloc_range(ida, 0, max, gfp); 333 } 334 335 static inline void ida_init(struct ida *ida) 336 { 337 xa_init_flags(&ida->xa, IDA_INIT_FLAGS); 338 } 339 340 static inline bool ida_is_empty(const struct ida *ida) 341 { 342 return xa_empty(&ida->xa); 343 } 344 345 static inline bool ida_exists(struct ida *ida, unsigned int id) 346 { 347 return ida_find_first_range(ida, id, id) == id; 348 } 349 350 static inline int ida_find_first(struct ida *ida) 351 { 352 return ida_find_first_range(ida, 0, ~0); 353 } 354 #endif /* __IDR_H__ */ 355