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  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/types.h>
  16. #include <errno-base.h>
  17. #include <linux/bitops.h>
  18. //#include <linux/init.h>
  19. //#include <linux/rcupdate.h>
  20.  
  21. struct rcu_head {
  22.     struct rcu_head *next;
  23.     void (*func)(struct rcu_head *head);
  24. };
  25.  
  26.  
  27. #if BITS_PER_LONG == 32
  28. # define IDR_BITS 5
  29. # define IDR_FULL 0xfffffffful
  30. /* We can only use two of the bits in the top level because there is
  31.    only one possible bit in the top level (5 bits * 7 levels = 35
  32.    bits, but you only use 31 bits in the id). */
  33. # define TOP_LEVEL_FULL (IDR_FULL >> 30)
  34. #elif BITS_PER_LONG == 64
  35. # define IDR_BITS 6
  36. # define IDR_FULL 0xfffffffffffffffful
  37. /* We can only use two of the bits in the top level because there is
  38.    only one possible bit in the top level (6 bits * 6 levels = 36
  39.    bits, but you only use 31 bits in the id). */
  40. # define TOP_LEVEL_FULL (IDR_FULL >> 62)
  41. #else
  42. # error "BITS_PER_LONG is not 32 or 64"
  43. #endif
  44.  
  45. #define IDR_SIZE (1 << IDR_BITS)
  46. #define IDR_MASK ((1 << IDR_BITS)-1)
  47.  
  48. #define MAX_ID_SHIFT (sizeof(int)*8 - 1)
  49. #define MAX_ID_BIT (1U << MAX_ID_SHIFT)
  50. #define MAX_ID_MASK (MAX_ID_BIT - 1)
  51.  
  52. /* Leave the possibility of an incomplete final layer */
  53. #define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS
  54.  
  55. /* Number of id_layer structs to leave in free list */
  56. #define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL
  57.  
  58. struct idr_layer {
  59.         unsigned long            bitmap; /* A zero bit means "space here" */
  60.         struct idr_layer __rcu  *ary[1<<IDR_BITS];
  61.         int                      count;  /* When zero, we can release it */
  62.         int                      layer;  /* distance from leaf */
  63.     struct rcu_head      rcu_head;
  64. };
  65.  
  66. struct idr {
  67.         struct idr_layer __rcu *top;
  68.         struct idr_layer *id_free;
  69.         int               layers; /* only valid without concurrent changes */
  70.         int               id_free_cnt;
  71. //   spinlock_t    lock;
  72. };
  73.  
  74. #define IDR_INIT(name)                                          \
  75. {                                                               \
  76.         .top            = NULL,                                 \
  77.         .id_free        = NULL,                                 \
  78.         .layers         = 0,                                    \
  79.         .id_free_cnt    = 0,                                    \
  80. //   .lock       = __SPIN_LOCK_UNLOCKED(name.lock),  \
  81. }
  82. #define DEFINE_IDR(name)        struct idr name = IDR_INIT(name)
  83.  
  84. /* Actions to be taken after a call to _idr_sub_alloc */
  85. #define IDR_NEED_TO_GROW -2
  86. #define IDR_NOMORE_SPACE -3
  87.  
  88. #define _idr_rc_to_errno(rc) ((rc) == -1 ? -EAGAIN : -ENOSPC)
  89.  
  90. /**
  91.  * DOC: idr sync
  92.  * idr synchronization (stolen from radix-tree.h)
  93.  *
  94.  * idr_find() is able to be called locklessly, using RCU. The caller must
  95.  * ensure calls to this function are made within rcu_read_lock() regions.
  96.  * Other readers (lock-free or otherwise) and modifications may be running
  97.  * concurrently.
  98.  *
  99.  * It is still required that the caller manage the synchronization and
  100.  * lifetimes of the items. So if RCU lock-free lookups are used, typically
  101.  * this would mean that the items have their own locks, or are amenable to
  102.  * lock-free access; and that the items are freed by RCU (or only freed after
  103.  * having been deleted from the idr tree *and* a synchronize_rcu() grace
  104.  * period).
  105.  */
  106.  
  107. /*
  108.  * This is what we export.
  109.  */
  110.  
  111. void *idr_find(struct idr *idp, int id);
  112. int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
  113. int idr_get_new(struct idr *idp, void *ptr, int *id);
  114. int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
  115. int idr_for_each(struct idr *idp,
  116.                  int (*fn)(int id, void *p, void *data), void *data);
  117. void *idr_get_next(struct idr *idp, int *nextid);
  118. void *idr_replace(struct idr *idp, void *ptr, int id);
  119. void idr_remove(struct idr *idp, int id);
  120. void idr_remove_all(struct idr *idp);
  121. void idr_destroy(struct idr *idp);
  122. void idr_init(struct idr *idp);
  123.  
  124.  
  125. /*
  126.  * IDA - IDR based id allocator, use when translation from id to
  127.  * pointer isn't necessary.
  128.  *
  129.  * IDA_BITMAP_LONGS is calculated to be one less to accommodate
  130.  * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes.
  131.  */
  132. #define IDA_CHUNK_SIZE          128     /* 128 bytes per chunk */
  133. #define IDA_BITMAP_LONGS        (IDA_CHUNK_SIZE / sizeof(long) - 1)
  134. #define IDA_BITMAP_BITS         (IDA_BITMAP_LONGS * sizeof(long) * 8)
  135.  
  136. struct ida_bitmap {
  137.         long                    nr_busy;
  138.         unsigned long           bitmap[IDA_BITMAP_LONGS];
  139. };
  140.  
  141. struct ida {
  142.         struct idr              idr;
  143.         struct ida_bitmap       *free_bitmap;
  144. };
  145.  
  146. #define IDA_INIT(name)          { .idr = IDR_INIT(name), .free_bitmap = NULL, }
  147. #define DEFINE_IDA(name)        struct ida name = IDA_INIT(name)
  148.  
  149. int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
  150. int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
  151. int ida_get_new(struct ida *ida, int *p_id);
  152. void ida_remove(struct ida *ida, int id);
  153. void ida_destroy(struct ida *ida);
  154. void ida_init(struct ida *ida);
  155.  
  156. void idr_init_cache(void);
  157.  
  158. #endif /* __IDR_H__ */
  159.