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           ((__force gfp_t)(3 << __GFP_BITS_SHIFT))
  33
  34 #define IDR_INIT_BASE(base) {                                           \
  35         .idr_rt = RADIX_TREE_INIT(IDR_RT_MARKER),                       \
  36         .idr_base = (base),                                             \
  37         .idr_next = 0,                                                  \
  38 }
  39
  40 /**
  41  * IDR_INIT() - Initialise an IDR.
  42  *
  43  * A freshly-initialised IDR contains no IDs.
  44  */
  45 #define IDR_INIT        IDR_INIT_BASE(0)
  46
  47 /**
  48  * DEFINE_IDR() - Define a statically-allocated IDR
  49  * @name: Name of IDR
  50  *
  51  * An IDR defined using this macro is ready for use with no additional
  52  * initialisation required.  It contains no IDs.
  53  */
  54 #define DEFINE_IDR(name)        struct idr name = IDR_INIT
  55
  56 /**
  57  * idr_get_cursor - Return the current position of the cyclic allocator
  58  * @idr: idr handle
  59  *
  60  * The value returned is the value that will be next returned from
  61  * idr_alloc_cyclic() if it is free (otherwise the search will start from
  62  * this position).
  63  */
  64 static inline unsigned int idr_get_cursor(const struct idr *idr)
  65 {
  66         return READ_ONCE(idr->idr_next);
  67 }
  68
  69 /**
  70  * idr_set_cursor - Set the current position of the cyclic allocator
  71  * @idr: idr handle
  72  * @val: new position
  73  *
  74  * The next call to idr_alloc_cyclic() will return @val if it is free
  75  * (otherwise the search will start from this position).
  76  */
  77 static inline void idr_set_cursor(struct idr *idr, unsigned int val)
  78 {
  79         WRITE_ONCE(idr->idr_next, val);
  80 }
  81
  82 /**
  83  * DOC: idr sync
  84  * idr synchronization (stolen from radix-tree.h)
  85  *
  86  * idr_find() is able to be called locklessly, using RCU. The caller must
  87  * ensure calls to this function are made within rcu_read_lock() regions.
  88  * Other readers (lock-free or otherwise) and modifications may be running
  89  * concurrently.
  90  *
  91  * It is still required that the caller manage the synchronization and
  92  * lifetimes of the items. So if RCU lock-free lookups are used, typically
  93  * this would mean that the items have their own locks, or are amenable to
  94  * lock-free access; and that the items are freed by RCU (or only freed after
  95  * having been deleted from the idr tree *and* a synchronize_rcu() grace
  96  * period).
  97  */
  98
  99 void idr_preload(gfp_t gfp_mask);
 100
 101 int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t);
 102 int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id,
 103                                 unsigned long max, gfp_t);
 104 int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t);
 105 void *idr_remove(struct idr *, unsigned long id);
 106 void *idr_find(const struct idr *, unsigned long id);
 107 int idr_for_each(const struct idr *,
 108                  int (*fn)(int id, void *p, void *data), void *data);
 109 void *idr_get_next(struct idr *, int *nextid);
 110 void *idr_get_next_ul(struct idr *, unsigned long *nextid);
 111 void *idr_replace(struct idr *, void *, unsigned long id);
 112 void idr_destroy(struct idr *);
 113
 114 /**
 115  * idr_init_base() - Initialise an IDR.
 116  * @idr: IDR handle.
 117  * @base: The base value for the IDR.
 118  *
 119  * This variation of idr_init() creates an IDR which will allocate IDs
 120  * starting at %base.
 121  */
 122 static inline void idr_init_base(struct idr *idr, int base)
 123 {
 124         INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER);
 125         idr->idr_base = base;
 126         idr->idr_next = 0;
 127 }
 128
 129 /**
 130  * idr_init() - Initialise an IDR.
 131  * @idr: IDR handle.
 132  *
 133  * Initialise a dynamically allocated IDR.  To initialise a
 134  * statically allocated IDR, use DEFINE_IDR().
 135  */
 136 static inline void idr_init(struct idr *idr)
 137 {
 138         idr_init_base(idr, 0);
 139 }
 140
 141 /**
 142  * idr_is_empty() - Are there any IDs allocated?
 143  * @idr: IDR handle.
 144  *
 145  * Return: %true if any IDs have been allocated from this IDR.
 146  */
 147 static inline bool idr_is_empty(const struct idr *idr)
 148 {
 149         return radix_tree_empty(&idr->idr_rt) &&
 150                 radix_tree_tagged(&idr->idr_rt, IDR_FREE);
 151 }
 152
 153 /**
 154  * idr_preload_end - end preload section started with idr_preload()
 155  *
 156  * Each idr_preload() should be matched with an invocation of this
 157  * function.  See idr_preload() for details.
 158  */
 159 static inline void idr_preload_end(void)
 160 {
 161         preempt_enable();
 162 }
 163
 164 /**
 165  * idr_for_each_entry() - Iterate over an IDR's elements of a given type.
 166  * @idr: IDR handle.
 167  * @entry: The type * to use as cursor
 168  * @id: Entry ID.
 169  *
 170  * @entry and @id do not need to be initialized before the loop, and
 171  * after normal termination @entry is left with the value NULL.  This
 172  * is convenient for a "not found" value.
 173  */
 174 #define idr_for_each_entry(idr, entry, id)                      \
 175         for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; ++id)
 176
 177 /**
 178  * idr_for_each_entry_ul() - 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_ul(idr, entry, id)                   \
 188         for (id = 0; ((entry) = idr_get_next_ul(idr, &(id))) != NULL; ++id)
 189
 190 /**
 191  * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type
 192  * @idr: IDR handle.
 193  * @entry: The type * to use as a cursor.
 194  * @id: Entry ID.
 195  *
 196  * Continue to iterate over entries, continuing after the current position.
 197  */
 198 #define idr_for_each_entry_continue(idr, entry, id)                     \
 199         for ((entry) = idr_get_next((idr), &(id));                      \
 200              entry;                                                     \
 201              ++id, (entry) = idr_get_next((idr), &(id)))
 202
 203 /*
 204  * IDA - IDR based id allocator, use when translation from id to
 205  * pointer isn't necessary.
 206  */
 207 #define IDA_CHUNK_SIZE          128     /* 128 bytes per chunk */
 208 #define IDA_BITMAP_LONGS        (IDA_CHUNK_SIZE / sizeof(long))
 209 #define IDA_BITMAP_BITS         (IDA_BITMAP_LONGS * sizeof(long) * 8)
 210
 211 struct ida_bitmap {
 212         unsigned long           bitmap[IDA_BITMAP_LONGS];
 213 };
 214
 215 DECLARE_PER_CPU(struct ida_bitmap *, ida_bitmap);
 216
 217 struct ida {
 218         struct radix_tree_root  ida_rt;
 219 };
 220
 221 #define IDA_INIT        {                                               \
 222         .ida_rt = RADIX_TREE_INIT(IDR_RT_MARKER | GFP_NOWAIT),          \
 223 }
 224 #define DEFINE_IDA(name)        struct ida name = IDA_INIT
 225
 226 int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
 227 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
 228 void ida_remove(struct ida *ida, int id);
 229 void ida_destroy(struct ida *ida);
 230
 231 int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
 232                    gfp_t gfp_mask);
 233 void ida_simple_remove(struct ida *ida, unsigned int id);
 234
 235 static inline void ida_init(struct ida *ida)
 236 {
 237         INIT_RADIX_TREE(&ida->ida_rt, IDR_RT_MARKER | GFP_NOWAIT);
 238 }
 239
 240 /**
 241  * ida_get_new - allocate new ID
 242  * @ida:        idr handle
 243  * @p_id:       pointer to the allocated handle
 244  *
 245  * Simple wrapper around ida_get_new_above() w/ @starting_id of zero.
 246  */
 247 static inline int ida_get_new(struct ida *ida, int *p_id)
 248 {
 249         return ida_get_new_above(ida, 0, p_id);
 250 }
 251
 252 static inline bool ida_is_empty(const struct ida *ida)
 253 {
 254         return radix_tree_empty(&ida->ida_rt);
 255 }
 256 #endif /* __IDR_H__ */