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 #include <linux/rcupdate.h> 19 20 #if BITS_PER_LONG == 32 21 # define IDR_BITS 5 22 # define IDR_FULL 0xfffffffful 23 /* We can only use two of the bits in the top level because there is 24 only one possible bit in the top level (5 bits * 7 levels = 35 25 bits, but you only use 31 bits in the id). */ 26 # define TOP_LEVEL_FULL (IDR_FULL >> 30) 27 #elif BITS_PER_LONG == 64 28 # define IDR_BITS 6 29 # define IDR_FULL 0xfffffffffffffffful 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 (6 bits * 6 levels = 36 32 bits, but you only use 31 bits in the id). */ 33 # define TOP_LEVEL_FULL (IDR_FULL >> 62) 34 #else 35 # error "BITS_PER_LONG is not 32 or 64" 36 #endif 37 38 #define IDR_SIZE (1 << IDR_BITS) 39 #define IDR_MASK ((1 << IDR_BITS)-1) 40 41 #define MAX_IDR_SHIFT (sizeof(int)*8 - 1) 42 #define MAX_IDR_BIT (1U << MAX_IDR_SHIFT) 43 #define MAX_IDR_MASK (MAX_IDR_BIT - 1) 44 45 /* Leave the possibility of an incomplete final layer */ 46 #define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS) 47 48 /* Number of id_layer structs to leave in free list */ 49 #define MAX_IDR_FREE (MAX_IDR_LEVEL * 2) 50 51 struct idr_layer { 52 unsigned long bitmap; /* A zero bit means "space here" */ 53 struct idr_layer __rcu *ary[1<<IDR_BITS]; 54 int count; /* When zero, we can release it */ 55 int layer; /* distance from leaf */ 56 struct rcu_head rcu_head; 57 }; 58 59 struct idr { 60 struct idr_layer __rcu *top; 61 struct idr_layer *id_free; 62 int layers; /* only valid w/o concurrent changes */ 63 int id_free_cnt; 64 spinlock_t lock; 65 }; 66 67 #define IDR_INIT(name) \ 68 { \ 69 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ 70 } 71 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name) 72 73 /** 74 * DOC: idr sync 75 * idr synchronization (stolen from radix-tree.h) 76 * 77 * idr_find() is able to be called locklessly, using RCU. The caller must 78 * ensure calls to this function are made within rcu_read_lock() regions. 79 * Other readers (lock-free or otherwise) and modifications may be running 80 * concurrently. 81 * 82 * It is still required that the caller manage the synchronization and 83 * lifetimes of the items. So if RCU lock-free lookups are used, typically 84 * this would mean that the items have their own locks, or are amenable to 85 * lock-free access; and that the items are freed by RCU (or only freed after 86 * having been deleted from the idr tree *and* a synchronize_rcu() grace 87 * period). 88 */ 89 90 /* 91 * This is what we export. 92 */ 93 94 void *idr_find(struct idr *idp, int id); 95 int idr_pre_get(struct idr *idp, gfp_t gfp_mask); 96 int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id); 97 void idr_preload(gfp_t gfp_mask); 98 int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask); 99 int idr_for_each(struct idr *idp, 100 int (*fn)(int id, void *p, void *data), void *data); 101 void *idr_get_next(struct idr *idp, int *nextid); 102 void *idr_replace(struct idr *idp, void *ptr, int id); 103 void idr_remove(struct idr *idp, int id); 104 void idr_free(struct idr *idp, int id); 105 void idr_destroy(struct idr *idp); 106 void idr_init(struct idr *idp); 107 108 /** 109 * idr_preload_end - end preload section started with idr_preload() 110 * 111 * Each idr_preload() should be matched with an invocation of this 112 * function. See idr_preload() for details. 113 */ 114 static inline void idr_preload_end(void) 115 { 116 preempt_enable(); 117 } 118 119 /** 120 * idr_get_new - allocate new idr entry 121 * @idp: idr handle 122 * @ptr: pointer you want associated with the id 123 * @id: pointer to the allocated handle 124 * 125 * Simple wrapper around idr_get_new_above() w/ @starting_id of zero. 126 */ 127 static inline int idr_get_new(struct idr *idp, void *ptr, int *id) 128 { 129 return idr_get_new_above(idp, ptr, 0, id); 130 } 131 132 /** 133 * idr_for_each_entry - iterate over an idr's elements of a given type 134 * @idp: idr handle 135 * @entry: the type * to use as cursor 136 * @id: id entry's key 137 */ 138 #define idr_for_each_entry(idp, entry, id) \ 139 for (id = 0, entry = (typeof(entry))idr_get_next((idp), &(id)); \ 140 entry != NULL; \ 141 ++id, entry = (typeof(entry))idr_get_next((idp), &(id))) 142 143 void __idr_remove_all(struct idr *idp); /* don't use */ 144 145 /** 146 * idr_remove_all - remove all ids from the given idr tree 147 * @idp: idr handle 148 * 149 * If you're trying to destroy @idp, calling idr_destroy() is enough. 150 * This is going away. Don't use. 151 */ 152 static inline void __deprecated idr_remove_all(struct idr *idp) 153 { 154 __idr_remove_all(idp); 155 } 156 157 /* 158 * IDA - IDR based id allocator, use when translation from id to 159 * pointer isn't necessary. 160 * 161 * IDA_BITMAP_LONGS is calculated to be one less to accommodate 162 * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes. 163 */ 164 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ 165 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1) 166 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) 167 168 struct ida_bitmap { 169 long nr_busy; 170 unsigned long bitmap[IDA_BITMAP_LONGS]; 171 }; 172 173 struct ida { 174 struct idr idr; 175 struct ida_bitmap *free_bitmap; 176 }; 177 178 #define IDA_INIT(name) { .idr = IDR_INIT((name).idr), .free_bitmap = NULL, } 179 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name) 180 181 int ida_pre_get(struct ida *ida, gfp_t gfp_mask); 182 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id); 183 void ida_remove(struct ida *ida, int id); 184 void ida_destroy(struct ida *ida); 185 void ida_init(struct ida *ida); 186 187 int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, 188 gfp_t gfp_mask); 189 void ida_simple_remove(struct ida *ida, unsigned int id); 190 191 /** 192 * ida_get_new - allocate new ID 193 * @ida: idr handle 194 * @p_id: pointer to the allocated handle 195 * 196 * Simple wrapper around ida_get_new_above() w/ @starting_id of zero. 197 */ 198 static inline int ida_get_new(struct ida *ida, int *p_id) 199 { 200 return ida_get_new_above(ida, 0, p_id); 201 } 202 203 void __init idr_init_cache(void); 204 205 #endif /* __IDR_H__ */ 206