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 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 */ idr_get_cursor(const struct idr * idr)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 */ idr_set_cursor(struct idr * idr,unsigned int val)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 #define idr_lock(idr) xa_lock(&(idr)->idr_rt) 102 #define idr_unlock(idr) xa_unlock(&(idr)->idr_rt) 103 #define idr_lock_bh(idr) xa_lock_bh(&(idr)->idr_rt) 104 #define idr_unlock_bh(idr) xa_unlock_bh(&(idr)->idr_rt) 105 #define idr_lock_irq(idr) xa_lock_irq(&(idr)->idr_rt) 106 #define idr_unlock_irq(idr) xa_unlock_irq(&(idr)->idr_rt) 107 #define idr_lock_irqsave(idr, flags) \ 108 xa_lock_irqsave(&(idr)->idr_rt, flags) 109 #define idr_unlock_irqrestore(idr, flags) \ 110 xa_unlock_irqrestore(&(idr)->idr_rt, flags) 111 112 void idr_preload(gfp_t gfp_mask); 113 114 int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t); 115 int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id, 116 unsigned long max, gfp_t); 117 int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t); 118 void *idr_remove(struct idr *, unsigned long id); 119 void *idr_find(const struct idr *, unsigned long id); 120 int idr_for_each(const struct idr *, 121 int (*fn)(int id, void *p, void *data), void *data); 122 void *idr_get_next(struct idr *, int *nextid); 123 void *idr_get_next_ul(struct idr *, unsigned long *nextid); 124 void *idr_replace(struct idr *, void *, unsigned long id); 125 void idr_destroy(struct idr *); 126 127 /** 128 * idr_init_base() - Initialise an IDR. 129 * @idr: IDR handle. 130 * @base: The base value for the IDR. 131 * 132 * This variation of idr_init() creates an IDR which will allocate IDs 133 * starting at %base. 134 */ idr_init_base(struct idr * idr,int base)135 static inline void idr_init_base(struct idr *idr, int base) 136 { 137 INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER); 138 idr->idr_base = base; 139 idr->idr_next = 0; 140 } 141 142 /** 143 * idr_init() - Initialise an IDR. 144 * @idr: IDR handle. 145 * 146 * Initialise a dynamically allocated IDR. To initialise a 147 * statically allocated IDR, use DEFINE_IDR(). 148 */ idr_init(struct idr * idr)149 static inline void idr_init(struct idr *idr) 150 { 151 idr_init_base(idr, 0); 152 } 153 154 /** 155 * idr_is_empty() - Are there any IDs allocated? 156 * @idr: IDR handle. 157 * 158 * Return: %true if any IDs have been allocated from this IDR. 159 */ idr_is_empty(const struct idr * idr)160 static inline bool idr_is_empty(const struct idr *idr) 161 { 162 return radix_tree_empty(&idr->idr_rt) && 163 radix_tree_tagged(&idr->idr_rt, IDR_FREE); 164 } 165 166 /** 167 * idr_preload_end - end preload section started with idr_preload() 168 * 169 * Each idr_preload() should be matched with an invocation of this 170 * function. See idr_preload() for details. 171 */ idr_preload_end(void)172 static inline void idr_preload_end(void) 173 { 174 local_unlock(&radix_tree_preloads.lock); 175 } 176 177 /** 178 * idr_for_each_entry() - Iterate over an IDR's elements of a given type. 179 * @idr: IDR handle. 180 * @entry: The type * to use as cursor 181 * @id: Entry ID. 182 * 183 * @entry and @id do not need to be initialized before the loop, and 184 * after normal termination @entry is left with the value NULL. This 185 * is convenient for a "not found" value. 186 */ 187 #define idr_for_each_entry(idr, entry, id) \ 188 for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; id += 1U) 189 190 /** 191 * idr_for_each_entry_ul() - Iterate over an IDR's elements of a given type. 192 * @idr: IDR handle. 193 * @entry: The type * to use as cursor. 194 * @tmp: A temporary placeholder for ID. 195 * @id: Entry ID. 196 * 197 * @entry and @id do not need to be initialized before the loop, and 198 * after normal termination @entry is left with the value NULL. This 199 * is convenient for a "not found" value. 200 */ 201 #define idr_for_each_entry_ul(idr, entry, tmp, id) \ 202 for (tmp = 0, id = 0; \ 203 ((entry) = tmp <= id ? idr_get_next_ul(idr, &(id)) : NULL) != NULL; \ 204 tmp = id, ++id) 205 206 /** 207 * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type 208 * @idr: IDR handle. 209 * @entry: The type * to use as a cursor. 210 * @id: Entry ID. 211 * 212 * Continue to iterate over entries, continuing after the current position. 213 */ 214 #define idr_for_each_entry_continue(idr, entry, id) \ 215 for ((entry) = idr_get_next((idr), &(id)); \ 216 entry; \ 217 ++id, (entry) = idr_get_next((idr), &(id))) 218 219 /** 220 * idr_for_each_entry_continue_ul() - Continue iteration over an IDR's elements of a given type 221 * @idr: IDR handle. 222 * @entry: The type * to use as a cursor. 223 * @tmp: A temporary placeholder for ID. 224 * @id: Entry ID. 225 * 226 * Continue to iterate over entries, continuing after the current position. 227 * After normal termination @entry is left with the value NULL. This 228 * is convenient for a "not found" value. 229 */ 230 #define idr_for_each_entry_continue_ul(idr, entry, tmp, id) \ 231 for (tmp = id; \ 232 ((entry) = tmp <= id ? idr_get_next_ul(idr, &(id)) : NULL) != NULL; \ 233 tmp = id, ++id) 234 235 /* 236 * IDA - ID Allocator, use when translation from id to pointer isn't necessary. 237 */ 238 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ 239 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long)) 240 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) 241 242 struct ida_bitmap { 243 unsigned long bitmap[IDA_BITMAP_LONGS]; 244 }; 245 246 struct ida { 247 struct xarray xa; 248 }; 249 250 #define IDA_INIT_FLAGS (XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC) 251 252 #define IDA_INIT(name) { \ 253 .xa = XARRAY_INIT(name, IDA_INIT_FLAGS) \ 254 } 255 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name) 256 257 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t); 258 void ida_free(struct ida *, unsigned int id); 259 void ida_destroy(struct ida *ida); 260 261 /** 262 * ida_alloc() - Allocate an unused ID. 263 * @ida: IDA handle. 264 * @gfp: Memory allocation flags. 265 * 266 * Allocate an ID between 0 and %INT_MAX, inclusive. 267 * 268 * Context: Any context. It is safe to call this function without 269 * locking in your code. 270 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated, 271 * or %-ENOSPC if there are no free IDs. 272 */ ida_alloc(struct ida * ida,gfp_t gfp)273 static inline int ida_alloc(struct ida *ida, gfp_t gfp) 274 { 275 return ida_alloc_range(ida, 0, ~0, gfp); 276 } 277 278 /** 279 * ida_alloc_min() - Allocate an unused ID. 280 * @ida: IDA handle. 281 * @min: Lowest ID to allocate. 282 * @gfp: Memory allocation flags. 283 * 284 * Allocate an ID between @min and %INT_MAX, inclusive. 285 * 286 * Context: Any context. It is safe to call this function without 287 * locking in your code. 288 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated, 289 * or %-ENOSPC if there are no free IDs. 290 */ ida_alloc_min(struct ida * ida,unsigned int min,gfp_t gfp)291 static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp) 292 { 293 return ida_alloc_range(ida, min, ~0, gfp); 294 } 295 296 /** 297 * ida_alloc_max() - Allocate an unused ID. 298 * @ida: IDA handle. 299 * @max: Highest ID to allocate. 300 * @gfp: Memory allocation flags. 301 * 302 * Allocate an ID between 0 and @max, inclusive. 303 * 304 * Context: Any context. It is safe to call this function without 305 * locking in your code. 306 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated, 307 * or %-ENOSPC if there are no free IDs. 308 */ ida_alloc_max(struct ida * ida,unsigned int max,gfp_t gfp)309 static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp) 310 { 311 return ida_alloc_range(ida, 0, max, gfp); 312 } 313 ida_init(struct ida * ida)314 static inline void ida_init(struct ida *ida) 315 { 316 xa_init_flags(&ida->xa, IDA_INIT_FLAGS); 317 } 318 319 /* 320 * ida_simple_get() and ida_simple_remove() are deprecated. Use 321 * ida_alloc() and ida_free() instead respectively. 322 */ 323 #define ida_simple_get(ida, start, end, gfp) \ 324 ida_alloc_range(ida, start, (end) - 1, gfp) 325 #define ida_simple_remove(ida, id) ida_free(ida, id) 326 ida_is_empty(const struct ida * ida)327 static inline bool ida_is_empty(const struct ida *ida) 328 { 329 return xa_empty(&ida->xa); 330 } 331 #endif /* __IDR_H__ */ 332