1 /* 2 * include/linux/idr.h 3 * 4 * 2002-10-18 written by Jim Houston [email protected] 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 19 #if BITS_PER_LONG == 32 20 # define IDR_BITS 5 21 # define IDR_FULL 0xfffffffful 22 /* We can only use two of the bits in the top level because there is 23 only one possible bit in the top level (5 bits * 7 levels = 35 24 bits, but you only use 31 bits in the id). */ 25 # define TOP_LEVEL_FULL (IDR_FULL >> 30) 26 #elif BITS_PER_LONG == 64 27 # define IDR_BITS 6 28 # define IDR_FULL 0xfffffffffffffffful 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 (6 bits * 6 levels = 36 31 bits, but you only use 31 bits in the id). */ 32 # define TOP_LEVEL_FULL (IDR_FULL >> 62) 33 #else 34 # error "BITS_PER_LONG is not 32 or 64" 35 #endif 36 37 #define IDR_SIZE (1 << IDR_BITS) 38 #define IDR_MASK ((1 << IDR_BITS)-1) 39 40 #define MAX_ID_SHIFT (sizeof(int)*8 - 1) 41 #define MAX_ID_BIT (1U << MAX_ID_SHIFT) 42 #define MAX_ID_MASK (MAX_ID_BIT - 1) 43 44 /* Leave the possibility of an incomplete final layer */ 45 #define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS 46 47 /* Number of id_layer structs to leave in free list */ 48 #define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL 49 50 struct idr_layer { 51 unsigned long bitmap; /* A zero bit means "space here" */ 52 struct idr_layer *ary[1<<IDR_BITS]; 53 int count; /* When zero, we can release it */ 54 }; 55 56 struct idr { 57 struct idr_layer *top; 58 struct idr_layer *id_free; 59 int layers; 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 /* 75 * This is what we export. 76 */ 77 78 void *idr_find(struct idr *idp, int id); 79 int idr_pre_get(struct idr *idp, gfp_t gfp_mask); 80 int idr_get_new(struct idr *idp, void *ptr, int *id); 81 int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id); 82 int idr_for_each(struct idr *idp, 83 int (*fn)(int id, void *p, void *data), void *data); 84 void *idr_replace(struct idr *idp, void *ptr, int id); 85 void idr_remove(struct idr *idp, int id); 86 void idr_remove_all(struct idr *idp); 87 void idr_destroy(struct idr *idp); 88 void idr_init(struct idr *idp); 89 90 91 /* 92 * IDA - IDR based id allocator, use when translation from id to 93 * pointer isn't necessary. 94 */ 95 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ 96 #define IDA_BITMAP_LONGS (128 / sizeof(long) - 1) 97 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) 98 99 struct ida_bitmap { 100 long nr_busy; 101 unsigned long bitmap[IDA_BITMAP_LONGS]; 102 }; 103 104 struct ida { 105 struct idr idr; 106 struct ida_bitmap *free_bitmap; 107 }; 108 109 #define IDA_INIT(name) { .idr = IDR_INIT(name), .free_bitmap = NULL, } 110 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name) 111 112 int ida_pre_get(struct ida *ida, gfp_t gfp_mask); 113 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id); 114 int ida_get_new(struct ida *ida, int *p_id); 115 void ida_remove(struct ida *ida, int id); 116 void ida_destroy(struct ida *ida); 117 void ida_init(struct ida *ida); 118 119 void __init idr_init_cache(void); 120 121 #endif /* __IDR_H__ */ 122