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 18 #if BITS_PER_LONG == 32 19 # define IDR_BITS 5 20 # define IDR_FULL 0xfffffffful 21 /* We can only use two of the bits in the top level because there is 22 only one possible bit in the top level (5 bits * 7 levels = 35 23 bits, but you only use 31 bits in the id). */ 24 # define TOP_LEVEL_FULL (IDR_FULL >> 30) 25 #elif BITS_PER_LONG == 64 26 # define IDR_BITS 6 27 # define IDR_FULL 0xfffffffffffffffful 28 /* We can only use two of the bits in the top level because there is 29 only one possible bit in the top level (6 bits * 6 levels = 36 30 bits, but you only use 31 bits in the id). */ 31 # define TOP_LEVEL_FULL (IDR_FULL >> 62) 32 #else 33 # error "BITS_PER_LONG is not 32 or 64" 34 #endif 35 36 #define IDR_SIZE (1 << IDR_BITS) 37 #define IDR_MASK ((1 << IDR_BITS)-1) 38 39 #define MAX_ID_SHIFT (sizeof(int)*8 - 1) 40 #define MAX_ID_BIT (1U << MAX_ID_SHIFT) 41 #define MAX_ID_MASK (MAX_ID_BIT - 1) 42 43 /* Leave the possibility of an incomplete final layer */ 44 #define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS 45 46 /* Number of id_layer structs to leave in free list */ 47 #define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL 48 49 struct idr_layer { 50 unsigned long bitmap; /* A zero bit means "space here" */ 51 struct idr_layer *ary[1<<IDR_BITS]; 52 int count; /* When zero, we can release it */ 53 }; 54 55 struct idr { 56 struct idr_layer *top; 57 struct idr_layer *id_free; 58 int layers; 59 int id_free_cnt; 60 spinlock_t lock; 61 }; 62 63 #define IDR_INIT(name) \ 64 { \ 65 .top = NULL, \ 66 .id_free = NULL, \ 67 .layers = 0, \ 68 .id_free_cnt = 0, \ 69 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ 70 } 71 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name) 72 73 /* 74 * This is what we export. 75 */ 76 77 void *idr_find(struct idr *idp, int id); 78 int idr_pre_get(struct idr *idp, gfp_t gfp_mask); 79 int idr_get_new(struct idr *idp, void *ptr, int *id); 80 int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id); 81 void *idr_replace(struct idr *idp, void *ptr, int id); 82 void idr_remove(struct idr *idp, int id); 83 void idr_destroy(struct idr *idp); 84 void idr_init(struct idr *idp); 85 86 #endif /* __IDR_H__ */ 87