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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 <types.h>
  16. #include <errno-base.h>
  17.  
  18. //#include <linux/bitops.h>
  19. //#include <linux/init.h>
  20. //#include <linux/rcupdate.h>
  21.  
  22. struct rcu_head {
  23.     struct rcu_head *next;
  24.     void (*func)(struct rcu_head *head);
  25. };
  26.  
  27.  
  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.  
  35. #define IDR_SIZE (1 << IDR_BITS)
  36. #define IDR_MASK ((1 << IDR_BITS)-1)
  37.  
  38. #define MAX_ID_SHIFT (sizeof(int)*8 - 1)
  39. #define MAX_ID_BIT (1U << MAX_ID_SHIFT)
  40. #define MAX_ID_MASK (MAX_ID_BIT - 1)
  41.  
  42. /* Leave the possibility of an incomplete final layer */
  43. #define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS
  44.  
  45. /* Number of id_layer structs to leave in free list */
  46. #define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL
  47.  
  48. struct idr_layer {
  49.         unsigned long            bitmap; /* A zero bit means "space here" */
  50.         struct idr_layer        *ary[1<<IDR_BITS];
  51.         int                      count;  /* When zero, we can release it */
  52.         int                      layer;  /* distance from leaf */
  53.     struct rcu_head      rcu_head;
  54. };
  55.  
  56. struct idr {
  57.         struct idr_layer *top;
  58.         struct idr_layer *id_free;
  59.         int               layers; /* only valid without concurrent changes */
  60.         int               id_free_cnt;
  61. //   spinlock_t    lock;
  62. };
  63.  
  64. #define IDR_INIT(name)                                          \
  65. {                                                               \
  66.         .top            = NULL,                                 \
  67.         .id_free        = NULL,                                 \
  68.         .layers         = 0,                                    \
  69.         .id_free_cnt    = 0,                                    \
  70. //   .lock       = __SPIN_LOCK_UNLOCKED(name.lock),  \
  71. }
  72. #define DEFINE_IDR(name)        struct idr name = IDR_INIT(name)
  73.  
  74. /* Actions to be taken after a call to _idr_sub_alloc */
  75. #define IDR_NEED_TO_GROW -2
  76. #define IDR_NOMORE_SPACE -3
  77.  
  78. #define _idr_rc_to_errno(rc) ((rc) == -1 ? -EAGAIN : -ENOSPC)
  79.  
  80. /**
  81.  * idr synchronization (stolen from radix-tree.h)
  82.  *
  83.  * idr_find() is able to be called locklessly, using RCU. The caller must
  84.  * ensure calls to this function are made within rcu_read_lock() regions.
  85.  * Other readers (lock-free or otherwise) and modifications may be running
  86.  * concurrently.
  87.  *
  88.  * It is still required that the caller manage the synchronization and
  89.  * lifetimes of the items. So if RCU lock-free lookups are used, typically
  90.  * this would mean that the items have their own locks, or are amenable to
  91.  * lock-free access; and that the items are freed by RCU (or only freed after
  92.  * having been deleted from the idr tree *and* a synchronize_rcu() grace
  93.  * period).
  94.  */
  95.  
  96. /*
  97.  * This is what we export.
  98.  */
  99.  
  100. void *idr_find(struct idr *idp, int id);
  101. int idr_pre_get(struct idr *idp, u32_t gfp_mask);
  102. int idr_get_new(struct idr *idp, void *ptr, int *id);
  103. int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
  104. int idr_for_each(struct idr *idp,
  105.                  int (*fn)(int id, void *p, void *data), void *data);
  106. void *idr_get_next(struct idr *idp, int *nextid);
  107. void *idr_replace(struct idr *idp, void *ptr, int id);
  108. void idr_remove(struct idr *idp, int id);
  109. void idr_remove_all(struct idr *idp);
  110. void idr_destroy(struct idr *idp);
  111. void idr_init(struct idr *idp);
  112.  
  113.  
  114. /*
  115.  * IDA - IDR based id allocator, use when translation from id to
  116.  * pointer isn't necessary.
  117.  */
  118. #define IDA_CHUNK_SIZE          128     /* 128 bytes per chunk */
  119. #define IDA_BITMAP_LONGS        (128 / sizeof(long) - 1)
  120. #define IDA_BITMAP_BITS         (IDA_BITMAP_LONGS * sizeof(long) * 8)
  121.  
  122. struct ida_bitmap {
  123.         long                    nr_busy;
  124.         unsigned long           bitmap[IDA_BITMAP_LONGS];
  125. };
  126.  
  127. struct ida {
  128.         struct idr              idr;
  129.         struct ida_bitmap       *free_bitmap;
  130. };
  131.  
  132. #define IDA_INIT(name)          { .idr = IDR_INIT(name), .free_bitmap = NULL, }
  133. #define DEFINE_IDA(name)        struct ida name = IDA_INIT(name)
  134.  
  135. int ida_pre_get(struct ida *ida, u32_t gfp_mask);
  136. int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
  137. int ida_get_new(struct ida *ida, int *p_id);
  138. void ida_remove(struct ida *ida, int id);
  139. void ida_destroy(struct ida *ida);
  140. void ida_init(struct ida *ida);
  141.  
  142. void idr_init_cache(void);
  143.  
  144. #endif /* __IDR_H__ */
  145.