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/inttypes.h>
30#include <sys/list.h>
31#include <sys/zfs_context.h>
32
33#ifdef	__cplusplus
34extern "C" {
35#endif
36
37/*
38 * If the reference is held only by the calling function and not any
39 * particular object, use FTAG (which is a string) for the holder_tag.
40 * Otherwise, use the object that holds the reference.
41 */
42#define	FTAG ((char *)(uintptr_t)__func__)
43
44#ifdef	ZFS_DEBUG
45typedef struct reference {
46	list_node_t ref_link;
47	void *ref_holder;
48	uint64_t ref_number;
49	uint8_t *ref_removed;
50} reference_t;
51
52typedef struct refcount {
53	kmutex_t rc_mtx;
54	boolean_t rc_tracked;
55	list_t rc_list;
56	list_t rc_removed;
57	uint64_t rc_count;
58	uint64_t rc_removed_count;
59} zfs_refcount_t;
60
61/*
62 * Note: zfs_refcount_t must be initialized with
63 * refcount_create[_untracked]()
64 */
65
66void zfs_refcount_create(zfs_refcount_t *);
67void zfs_refcount_create_untracked(zfs_refcount_t *);
68void zfs_refcount_create_tracked(zfs_refcount_t *);
69void zfs_refcount_destroy(zfs_refcount_t *);
70void zfs_refcount_destroy_many(zfs_refcount_t *, uint64_t);
71int zfs_refcount_is_zero(zfs_refcount_t *);
72int64_t zfs_refcount_count(zfs_refcount_t *);
73int64_t zfs_refcount_add(zfs_refcount_t *, void *);
74int64_t zfs_refcount_remove(zfs_refcount_t *, void *);
75int64_t zfs_refcount_add_many(zfs_refcount_t *, uint64_t, void *);
76int64_t zfs_refcount_remove_many(zfs_refcount_t *, uint64_t, void *);
77void zfs_refcount_transfer(zfs_refcount_t *, zfs_refcount_t *);
78void zfs_refcount_transfer_ownership(zfs_refcount_t *, void *, void *);
79void zfs_refcount_transfer_ownership_many(zfs_refcount_t *, uint64_t,
80    void *, void *);
81boolean_t zfs_refcount_held(zfs_refcount_t *, void *);
82boolean_t zfs_refcount_not_held(zfs_refcount_t *, void *);
83
84void zfs_refcount_init(void);
85void zfs_refcount_fini(void);
86
87#else	/* ZFS_DEBUG */
88
89typedef struct refcount {
90	uint64_t rc_count;
91} zfs_refcount_t;
92
93#define	zfs_refcount_create(rc) ((rc)->rc_count = 0)
94#define	zfs_refcount_create_untracked(rc) ((rc)->rc_count = 0)
95#define	zfs_refcount_create_tracked(rc) ((rc)->rc_count = 0)
96#define	zfs_refcount_destroy(rc) ((rc)->rc_count = 0)
97#define	zfs_refcount_destroy_many(rc, number) ((rc)->rc_count = 0)
98#define	zfs_refcount_is_zero(rc) ((rc)->rc_count == 0)
99#define	zfs_refcount_count(rc) ((rc)->rc_count)
100#define	zfs_refcount_add(rc, holder) atomic_inc_64_nv(&(rc)->rc_count)
101#define	zfs_refcount_remove(rc, holder) atomic_dec_64_nv(&(rc)->rc_count)
102#define	zfs_refcount_add_many(rc, number, holder) \
103	atomic_add_64_nv(&(rc)->rc_count, number)
104#define	zfs_refcount_remove_many(rc, number, holder) \
105	atomic_add_64_nv(&(rc)->rc_count, -number)
106#define	zfs_refcount_transfer(dst, src) { \
107	uint64_t __tmp = (src)->rc_count; \
108	atomic_add_64(&(src)->rc_count, -__tmp); \
109	atomic_add_64(&(dst)->rc_count, __tmp); \
110}
111#define	zfs_refcount_transfer_ownership(rc, current_holder, new_holder)	(void)0
112#define	zfs_refcount_transfer_ownership_many(rc, nr, ch, nh)	((void)0)
113#define	zfs_refcount_held(rc, holder)		((rc)->rc_count > 0)
114#define	zfs_refcount_not_held(rc, holder)		(B_TRUE)
115
116#define	zfs_refcount_init()
117#define	zfs_refcount_fini()
118
119#endif	/* ZFS_DEBUG */
120
121#ifdef	__cplusplus
122}
123#endif
124
125#endif /* _SYS_REFCOUNT_H */
126