xref: /titanic_41/usr/src/uts/common/fs/zfs/sys/refcount.h (revision 0d6bb4c6728fd20087fe25f4028a3838250e6e9c)
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 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
34 extern "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 *)__func__)
43 
44 #ifdef	ZFS_DEBUG
45 typedef 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 
52 typedef 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 } refcount_t;
60 
61 /* Note: refcount_t must be initialized with refcount_create[_untracked]() */
62 
63 void refcount_create(refcount_t *rc);
64 void refcount_create_untracked(refcount_t *rc);
65 void refcount_destroy(refcount_t *rc);
66 void refcount_destroy_many(refcount_t *rc, uint64_t number);
67 int refcount_is_zero(refcount_t *rc);
68 int64_t refcount_count(refcount_t *rc);
69 int64_t refcount_add(refcount_t *rc, void *holder_tag);
70 int64_t refcount_remove(refcount_t *rc, void *holder_tag);
71 int64_t refcount_add_many(refcount_t *rc, uint64_t number, void *holder_tag);
72 int64_t refcount_remove_many(refcount_t *rc, uint64_t number, void *holder_tag);
73 void refcount_transfer(refcount_t *dst, refcount_t *src);
74 
75 void refcount_init(void);
76 void refcount_fini(void);
77 
78 #else	/* ZFS_DEBUG */
79 
80 typedef struct refcount {
81 	uint64_t rc_count;
82 } refcount_t;
83 
84 #define	refcount_create(rc) ((rc)->rc_count = 0)
85 #define	refcount_create_untracked(rc) ((rc)->rc_count = 0)
86 #define	refcount_destroy(rc) ((rc)->rc_count = 0)
87 #define	refcount_destroy_many(rc, number) ((rc)->rc_count = 0)
88 #define	refcount_is_zero(rc) ((rc)->rc_count == 0)
89 #define	refcount_count(rc) ((rc)->rc_count)
90 #define	refcount_add(rc, holder) atomic_inc_64_nv(&(rc)->rc_count)
91 #define	refcount_remove(rc, holder) atomic_dec_64_nv(&(rc)->rc_count)
92 #define	refcount_add_many(rc, number, holder) \
93 	atomic_add_64_nv(&(rc)->rc_count, number)
94 #define	refcount_remove_many(rc, number, holder) \
95 	atomic_add_64_nv(&(rc)->rc_count, -number)
96 #define	refcount_transfer(dst, src) { \
97 	uint64_t __tmp = (src)->rc_count; \
98 	atomic_add_64(&(src)->rc_count, -__tmp); \
99 	atomic_add_64(&(dst)->rc_count, __tmp); \
100 }
101 
102 #define	refcount_init()
103 #define	refcount_fini()
104 
105 #endif	/* ZFS_DEBUG */
106 
107 #ifdef	__cplusplus
108 }
109 #endif
110 
111 #endif /* _SYS_REFCOUNT_H */
112