include/linux/idr.h

   1 /*
   2  * include/linux/idr.h
   3  *
   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.
   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 #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  */
 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  */
 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  */
 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  */
 172 static inline void idr_preload_end(void)
 173 {
 174         preempt_enable();
 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)
 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  * @id: Entry ID.
 195  *
 196  * @entry and @id do not need to be initialized before the loop, and
 197  * after normal termination @entry is left with the value NULL.  This
 198  * is convenient for a "not found" value.
 199  */
 200 #define idr_for_each_entry_ul(idr, entry, id)                   \
 201         for (id = 0; ((entry) = idr_get_next_ul(idr, &(id))) != NULL; ++id)
 202
 203 /**
 204  * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type
 205  * @idr: IDR handle.
 206  * @entry: The type * to use as a cursor.
 207  * @id: Entry ID.
 208  *
 209  * Continue to iterate over entries, continuing after the current position.
 210  */
 211 #define idr_for_each_entry_continue(idr, entry, id)                     \
 212         for ((entry) = idr_get_next((idr), &(id));                      \
 213              entry;                                                     \
 214              ++id, (entry) = idr_get_next((idr), &(id)))
 215
 216 /*
 217  * IDA - IDR based id allocator, use when translation from id to
 218  * pointer isn't necessary.
 219  */
 220 #define IDA_CHUNK_SIZE          128     /* 128 bytes per chunk */
 221 #define IDA_BITMAP_LONGS        (IDA_CHUNK_SIZE / sizeof(long))
 222 #define IDA_BITMAP_BITS         (IDA_BITMAP_LONGS * sizeof(long) * 8)
 223
 224 struct ida_bitmap {
 225         unsigned long           bitmap[IDA_BITMAP_LONGS];
 226 };
 227
 228 DECLARE_PER_CPU(struct ida_bitmap *, ida_bitmap);
 229
 230 struct ida {
 231         struct radix_tree_root  ida_rt;
 232 };
 233
 234 #define IDA_INIT(name)  {                                               \
 235         .ida_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER | GFP_NOWAIT),    \
 236 }
 237 #define DEFINE_IDA(name)        struct ida name = IDA_INIT(name)
 238
 239 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
 240 void ida_free(struct ida *, unsigned int id);
 241 void ida_destroy(struct ida *ida);
 242
 243 /**
 244  * ida_alloc() - Allocate an unused ID.
 245  * @ida: IDA handle.
 246  * @gfp: Memory allocation flags.
 247  *
 248  * Allocate an ID between 0 and %INT_MAX, inclusive.
 249  *
 250  * Context: Any context.
 251  * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
 252  * or %-ENOSPC if there are no free IDs.
 253  */
 254 static inline int ida_alloc(struct ida *ida, gfp_t gfp)
 255 {
 256         return ida_alloc_range(ida, 0, ~0, gfp);
 257 }
 258
 259 /**
 260  * ida_alloc_min() - Allocate an unused ID.
 261  * @ida: IDA handle.
 262  * @min: Lowest ID to allocate.
 263  * @gfp: Memory allocation flags.
 264  *
 265  * Allocate an ID between @min and %INT_MAX, inclusive.
 266  *
 267  * Context: Any context.
 268  * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
 269  * or %-ENOSPC if there are no free IDs.
 270  */
 271 static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp)
 272 {
 273         return ida_alloc_range(ida, min, ~0, gfp);
 274 }
 275
 276 /**
 277  * ida_alloc_max() - Allocate an unused ID.
 278  * @ida: IDA handle.
 279  * @max: Highest ID to allocate.
 280  * @gfp: Memory allocation flags.
 281  *
 282  * Allocate an ID between 0 and @max, inclusive.
 283  *
 284  * Context: Any context.
 285  * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
 286  * or %-ENOSPC if there are no free IDs.
 287  */
 288 static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp)
 289 {
 290         return ida_alloc_range(ida, 0, max, gfp);
 291 }
 292
 293 static inline void ida_init(struct ida *ida)
 294 {
 295         INIT_RADIX_TREE(&ida->ida_rt, IDR_RT_MARKER | GFP_NOWAIT);
 296 }
 297
 298 #define ida_simple_get(ida, start, end, gfp)    \
 299                         ida_alloc_range(ida, start, (end) - 1, gfp)
 300 #define ida_simple_remove(ida, id)      ida_free(ida, id)
 301
 302 static inline bool ida_is_empty(const struct ida *ida)
 303 {
 304         return radix_tree_empty(&ida->ida_rt);
 305 }
 306
 307 /* in lib/radix-tree.c */
 308 int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
 309 #endif /* __IDR_H__ */