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