fd4f2df24b
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
79 lines
2.2 KiB
C
79 lines
2.2 KiB
C
/*
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* include/linux/idr.h
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*
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* 2002-10-18 written by Jim Houston jim.houston@ccur.com
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* Copyright (C) 2002 by Concurrent Computer Corporation
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* Distributed under the GNU GPL license version 2.
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*
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* Small id to pointer translation service avoiding fixed sized
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* tables.
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*/
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#include <linux/types.h>
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#include <linux/bitops.h>
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#if BITS_PER_LONG == 32
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# define IDR_BITS 5
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# define IDR_FULL 0xfffffffful
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/* We can only use two of the bits in the top level because there is
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only one possible bit in the top level (5 bits * 7 levels = 35
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bits, but you only use 31 bits in the id). */
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# define TOP_LEVEL_FULL (IDR_FULL >> 30)
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#elif BITS_PER_LONG == 64
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# define IDR_BITS 6
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# define IDR_FULL 0xfffffffffffffffful
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/* We can only use two of the bits in the top level because there is
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only one possible bit in the top level (6 bits * 6 levels = 36
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bits, but you only use 31 bits in the id). */
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# define TOP_LEVEL_FULL (IDR_FULL >> 62)
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#else
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# error "BITS_PER_LONG is not 32 or 64"
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#endif
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#define IDR_SIZE (1 << IDR_BITS)
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#define IDR_MASK ((1 << IDR_BITS)-1)
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#define MAX_ID_SHIFT (sizeof(int)*8 - 1)
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#define MAX_ID_BIT (1U << MAX_ID_SHIFT)
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#define MAX_ID_MASK (MAX_ID_BIT - 1)
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/* Leave the possibility of an incomplete final layer */
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#define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS
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/* Number of id_layer structs to leave in free list */
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#define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL
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struct idr_layer {
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unsigned long bitmap; /* A zero bit means "space here" */
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struct idr_layer *ary[1<<IDR_BITS];
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int count; /* When zero, we can release it */
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};
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struct idr {
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struct idr_layer *top;
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struct idr_layer *id_free;
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int layers;
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int id_free_cnt;
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spinlock_t lock;
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};
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#define IDR_INIT(name) \
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{ \
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.top = NULL, \
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.id_free = NULL, \
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.layers = 0, \
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.id_free_cnt = 0, \
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.lock = SPIN_LOCK_UNLOCKED, \
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}
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#define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
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/*
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* This is what we export.
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*/
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void *idr_find(struct idr *idp, int id);
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int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
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int idr_get_new(struct idr *idp, void *ptr, int *id);
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int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
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void idr_remove(struct idr *idp, int id);
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void idr_destroy(struct idr *idp);
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void idr_init(struct idr *idp);
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