refcount.h revision 307279 
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
24 */
25
26#ifndef	_SYS_REFCOUNT_H
27#define	_SYS_REFCOUNT_H
28
29#include <sys/cdefs.h>
30#include <sys/types.h>
31#include_next <sys/refcount.h>
32#include <sys/list.h>
33#include <sys/zfs_context.h>
34
35#ifdef	__cplusplus
36extern "C" {
37#endif
38
39/*
40 * If the reference is held only by the calling function and not any
41 * particular object, use FTAG (which is a string) for the holder_tag.
42 * Otherwise, use the object that holds the reference.
43 */
44#define	FTAG ((char *)__func__)
45
46#ifdef	ZFS_DEBUG
47typedef struct reference {
48	list_node_t ref_link;
49	void *ref_holder;
50	uint64_t ref_number;
51	uint8_t *ref_removed;
52} reference_t;
53
54typedef struct refcount {
55	kmutex_t rc_mtx;
56	boolean_t rc_tracked;
57	list_t rc_list;
58	list_t rc_removed;
59	uint64_t rc_count;
60	uint64_t rc_removed_count;
61} refcount_t;
62
63/* Note: refcount_t must be initialized with refcount_create[_untracked]() */
64
65void refcount_create(refcount_t *rc);
66void refcount_create_untracked(refcount_t *rc);
67void refcount_create_tracked(refcount_t *rc);
68void refcount_destroy(refcount_t *rc);
69void refcount_destroy_many(refcount_t *rc, uint64_t number);
70int refcount_is_zero(refcount_t *rc);
71int64_t refcount_count(refcount_t *rc);
72int64_t refcount_add(refcount_t *rc, void *holder_tag);
73int64_t refcount_remove(refcount_t *rc, void *holder_tag);
74int64_t refcount_add_many(refcount_t *rc, uint64_t number, void *holder_tag);
75int64_t refcount_remove_many(refcount_t *rc, uint64_t number, void *holder_tag);
76void refcount_transfer(refcount_t *dst, refcount_t *src);
77void refcount_transfer_ownership(refcount_t *, void *, void *);
78boolean_t refcount_held(refcount_t *, void *);
79boolean_t refcount_not_held(refcount_t *, void *);
80
81void refcount_sysinit(void);
82void refcount_fini(void);
83
84#else	/* ZFS_DEBUG */
85
86typedef struct refcount {
87	uint64_t rc_count;
88} refcount_t;
89
90#define	refcount_create(rc) ((rc)->rc_count = 0)
91#define	refcount_create_untracked(rc) ((rc)->rc_count = 0)
92#define	refcount_create_tracked(rc) ((rc)->rc_count = 0)
93#define	refcount_destroy(rc) ((rc)->rc_count = 0)
94#define	refcount_destroy_many(rc, number) ((rc)->rc_count = 0)
95#define	refcount_is_zero(rc) ((rc)->rc_count == 0)
96#define	refcount_count(rc) ((rc)->rc_count)
97#define	refcount_add(rc, holder) atomic_inc_64_nv(&(rc)->rc_count)
98#define	refcount_remove(rc, holder) atomic_dec_64_nv(&(rc)->rc_count)
99#define	refcount_add_many(rc, number, holder) \
100	atomic_add_64_nv(&(rc)->rc_count, number)
101#define	refcount_remove_many(rc, number, holder) \
102	atomic_add_64_nv(&(rc)->rc_count, -number)
103#define	refcount_transfer(dst, src) { \
104	uint64_t __tmp = (src)->rc_count; \
105	atomic_add_64(&(src)->rc_count, -__tmp); \
106	atomic_add_64(&(dst)->rc_count, __tmp); \
107}
108#define	refcount_transfer_ownership(rc, current_holder, new_holder)
109#define	refcount_held(rc, holder)		((rc)->rc_count > 0)
110#define	refcount_not_held(rc, holder)		(B_TRUE)
111
112#define	refcount_sysinit()
113#define	refcount_fini()
114
115#endif	/* ZFS_DEBUG */
116
117#ifdef	__cplusplus
118}
119#endif
120
121#endif /* _SYS_REFCOUNT_H */
122