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 #include <linux/types.h> 12 #include <linux/bitops.h> 13 14 #if BITS_PER_LONG == 32 15 # define IDR_BITS 5 16 # define IDR_FULL 0xfffffffful 17 /* We can only use two of the bits in the top level because there is 18 only one possible bit in the top level (5 bits * 7 levels = 35 19 bits, but you only use 31 bits in the id). */ 20 # define TOP_LEVEL_FULL (IDR_FULL >> 30) 21 #elif BITS_PER_LONG == 64 22 # define IDR_BITS 6 23 # define IDR_FULL 0xfffffffffffffffful 24 /* We can only use two of the bits in the top level because there is 25 only one possible bit in the top level (6 bits * 6 levels = 36 26 bits, but you only use 31 bits in the id). */ 27 # define TOP_LEVEL_FULL (IDR_FULL >> 62) 28 #else 29 # error "BITS_PER_LONG is not 32 or 64" 30 #endif 31 32 #define IDR_SIZE (1 << IDR_BITS) 33 #define IDR_MASK ((1 << IDR_BITS)-1) 34 35 #define MAX_ID_SHIFT (sizeof(int)*8 - 1) 36 #define MAX_ID_BIT (1U << MAX_ID_SHIFT) 37 #define MAX_ID_MASK (MAX_ID_BIT - 1) 38 39 /* Leave the possibility of an incomplete final layer */ 40 #define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS 41 42 /* Number of id_layer structs to leave in free list */ 43 #define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL 44 45 struct idr_layer { 46 unsigned long bitmap; /* A zero bit means "space here" */ 47 struct idr_layer *ary[1<<IDR_BITS]; 48 int count; /* When zero, we can release it */ 49 }; 50 51 struct idr { 52 struct idr_layer *top; 53 struct idr_layer *id_free; 54 int layers; 55 int id_free_cnt; 56 spinlock_t lock; 57 }; 58 59 #define IDR_INIT(name) \ 60 { \ 61 .top = NULL, \ 62 .id_free = NULL, \ 63 .layers = 0, \ 64 .id_free_cnt = 0, \ 65 .lock = SPIN_LOCK_UNLOCKED, \ 66 } 67 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name) 68 69 /* 70 * This is what we export. 71 */ 72 73 void *idr_find(struct idr *idp, int id); 74 int idr_pre_get(struct idr *idp, unsigned gfp_mask); 75 int idr_get_new(struct idr *idp, void *ptr, int *id); 76 int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id); 77 void idr_remove(struct idr *idp, int id); 78 void idr_init(struct idr *idp); 79