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Diffstat (limited to 'include/linux/idr.h')
| -rw-r--r-- | include/linux/idr.h | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/include/linux/idr.h b/include/linux/idr.h new file mode 100644 index 00000000..13a801f3 --- /dev/null +++ b/include/linux/idr.h @@ -0,0 +1,151 @@ +/* + * include/linux/idr.h + * + * 2002-10-18 written by Jim Houston jim.houston@ccur.com + * Copyright (C) 2002 by Concurrent Computer Corporation + * Distributed under the GNU GPL license version 2. + * + * Small id to pointer translation service avoiding fixed sized + * tables. + */ + +#ifndef __IDR_H__ +#define __IDR_H__ + +#include <linux/types.h> +#include <linux/bitops.h> +#include <linux/init.h> +#include <linux/rcupdate.h> + +#if BITS_PER_LONG == 32 +# define IDR_BITS 5 +# define IDR_FULL 0xfffffffful +/* We can only use two of the bits in the top level because there is + only one possible bit in the top level (5 bits * 7 levels = 35 + bits, but you only use 31 bits in the id). */ +# define TOP_LEVEL_FULL (IDR_FULL >> 30) +#elif BITS_PER_LONG == 64 +# define IDR_BITS 6 +# define IDR_FULL 0xfffffffffffffffful +/* We can only use two of the bits in the top level because there is + only one possible bit in the top level (6 bits * 6 levels = 36 + bits, but you only use 31 bits in the id). */ +# define TOP_LEVEL_FULL (IDR_FULL >> 62) +#else +# error "BITS_PER_LONG is not 32 or 64" +#endif + +#define IDR_SIZE (1 << IDR_BITS) +#define IDR_MASK ((1 << IDR_BITS)-1) + +#define MAX_ID_SHIFT (sizeof(int)*8 - 1) +#define MAX_ID_BIT (1U << MAX_ID_SHIFT) +#define MAX_ID_MASK (MAX_ID_BIT - 1) + +/* Leave the possibility of an incomplete final layer */ +#define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS + +/* Number of id_layer structs to leave in free list */ +#define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL + +struct idr_layer { + unsigned long bitmap; /* A zero bit means "space here" */ + struct idr_layer __rcu *ary[1<<IDR_BITS]; + int count; /* When zero, we can release it */ + int layer; /* distance from leaf */ + struct rcu_head rcu_head; +}; + +struct idr { + struct idr_layer __rcu *top; + struct idr_layer *id_free; + int layers; /* only valid without concurrent changes */ + int id_free_cnt; + spinlock_t lock; +}; + +#define IDR_INIT(name) \ +{ \ + .top = NULL, \ + .id_free = NULL, \ + .layers = 0, \ + .id_free_cnt = 0, \ + .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ +} +#define DEFINE_IDR(name) struct idr name = IDR_INIT(name) + +/* Actions to be taken after a call to _idr_sub_alloc */ +#define IDR_NEED_TO_GROW -2 +#define IDR_NOMORE_SPACE -3 + +#define _idr_rc_to_errno(rc) ((rc) == -1 ? -EAGAIN : -ENOSPC) + +/** + * DOC: idr sync + * idr synchronization (stolen from radix-tree.h) + * + * idr_find() is able to be called locklessly, using RCU. The caller must + * ensure calls to this function are made within rcu_read_lock() regions. + * Other readers (lock-free or otherwise) and modifications may be running + * concurrently. + * + * It is still required that the caller manage the synchronization and + * lifetimes of the items. So if RCU lock-free lookups are used, typically + * this would mean that the items have their own locks, or are amenable to + * lock-free access; and that the items are freed by RCU (or only freed after + * having been deleted from the idr tree *and* a synchronize_rcu() grace + * period). + */ + +/* + * This is what we export. + */ + +void *idr_find(struct idr *idp, int id); +int idr_pre_get(struct idr *idp, gfp_t gfp_mask); +int idr_get_new(struct idr *idp, void *ptr, int *id); +int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id); +int idr_for_each(struct idr *idp, + int (*fn)(int id, void *p, void *data), void *data); +void *idr_get_next(struct idr *idp, int *nextid); +void *idr_replace(struct idr *idp, void *ptr, int id); +void idr_remove(struct idr *idp, int id); +void idr_remove_all(struct idr *idp); +void idr_destroy(struct idr *idp); +void idr_init(struct idr *idp); + + +/* + * IDA - IDR based id allocator, use when translation from id to + * pointer isn't necessary. + * + * IDA_BITMAP_LONGS is calculated to be one less to accommodate + * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes. + */ +#define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ +#define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1) +#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) + +struct ida_bitmap { + long nr_busy; + unsigned long bitmap[IDA_BITMAP_LONGS]; +}; + +struct ida { + struct idr idr; + struct ida_bitmap *free_bitmap; +}; + +#define IDA_INIT(name) { .idr = IDR_INIT(name), .free_bitmap = NULL, } +#define DEFINE_IDA(name) struct ida name = IDA_INIT(name) + +int ida_pre_get(struct ida *ida, gfp_t gfp_mask); +int ida_get_new_above(struct ida *ida, int starting_id, int *p_id); +int ida_get_new(struct ida *ida, int *p_id); +void ida_remove(struct ida *ida, int id); +void ida_destroy(struct ida *ida); +void ida_init(struct ida *ida); + +void __init idr_init_cache(void); + +#endif /* __IDR_H__ */ |