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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 2007 Sun Microsystems, Inc. All rights reserved. | |
23 | * Use is subject to license terms. | |
24 | */ | |
25 | ||
26 | #pragma ident "%Z%%M% %I% %E% SMI" | |
27 | ||
28 | #include <sys/zfs_context.h> | |
29 | #include <sys/refcount.h> | |
30 | ||
31 | #if defined(DEBUG) || !defined(_KERNEL) | |
32 | ||
33 | #ifdef _KERNEL | |
34 | int reference_tracking_enable = FALSE; /* runs out of memory too easily */ | |
35 | #else | |
36 | int reference_tracking_enable = TRUE; | |
37 | #endif | |
38 | int reference_history = 4; /* tunable */ | |
39 | ||
40 | static kmem_cache_t *reference_cache; | |
41 | static kmem_cache_t *reference_history_cache; | |
42 | ||
43 | void | |
44 | refcount_init(void) | |
45 | { | |
46 | reference_cache = kmem_cache_create("reference_cache", | |
47 | sizeof (reference_t), 0, NULL, NULL, NULL, NULL, NULL, 0); | |
48 | ||
49 | reference_history_cache = kmem_cache_create("reference_history_cache", | |
50 | sizeof (uint64_t), 0, NULL, NULL, NULL, NULL, NULL, 0); | |
51 | } | |
52 | ||
53 | void | |
54 | refcount_fini(void) | |
55 | { | |
56 | kmem_cache_destroy(reference_cache); | |
57 | kmem_cache_destroy(reference_history_cache); | |
58 | } | |
59 | ||
60 | void | |
61 | refcount_create(refcount_t *rc) | |
62 | { | |
63 | mutex_init(&rc->rc_mtx, NULL, MUTEX_DEFAULT, NULL); | |
64 | list_create(&rc->rc_list, sizeof (reference_t), | |
65 | offsetof(reference_t, ref_link)); | |
66 | list_create(&rc->rc_removed, sizeof (reference_t), | |
67 | offsetof(reference_t, ref_link)); | |
68 | rc->rc_count = 0; | |
69 | rc->rc_removed_count = 0; | |
70 | } | |
71 | ||
72 | void | |
73 | refcount_destroy_many(refcount_t *rc, uint64_t number) | |
74 | { | |
75 | reference_t *ref; | |
76 | ||
77 | ASSERT(rc->rc_count == number); | |
78 | while (ref = list_head(&rc->rc_list)) { | |
79 | list_remove(&rc->rc_list, ref); | |
80 | kmem_cache_free(reference_cache, ref); | |
81 | } | |
82 | list_destroy(&rc->rc_list); | |
83 | ||
84 | while (ref = list_head(&rc->rc_removed)) { | |
85 | list_remove(&rc->rc_removed, ref); | |
86 | kmem_cache_free(reference_history_cache, ref->ref_removed); | |
87 | kmem_cache_free(reference_cache, ref); | |
88 | } | |
89 | list_destroy(&rc->rc_removed); | |
90 | mutex_destroy(&rc->rc_mtx); | |
91 | } | |
92 | ||
93 | void | |
94 | refcount_destroy(refcount_t *rc) | |
95 | { | |
96 | refcount_destroy_many(rc, 0); | |
97 | } | |
98 | ||
99 | int | |
100 | refcount_is_zero(refcount_t *rc) | |
101 | { | |
102 | ASSERT(rc->rc_count >= 0); | |
103 | return (rc->rc_count == 0); | |
104 | } | |
105 | ||
106 | int64_t | |
107 | refcount_count(refcount_t *rc) | |
108 | { | |
109 | ASSERT(rc->rc_count >= 0); | |
110 | return (rc->rc_count); | |
111 | } | |
112 | ||
113 | int64_t | |
114 | refcount_add_many(refcount_t *rc, uint64_t number, void *holder) | |
115 | { | |
116 | reference_t *ref; | |
117 | int64_t count; | |
118 | ||
119 | if (reference_tracking_enable) { | |
120 | ref = kmem_cache_alloc(reference_cache, KM_SLEEP); | |
121 | ref->ref_holder = holder; | |
122 | ref->ref_number = number; | |
123 | } | |
124 | mutex_enter(&rc->rc_mtx); | |
125 | ASSERT(rc->rc_count >= 0); | |
126 | if (reference_tracking_enable) | |
127 | list_insert_head(&rc->rc_list, ref); | |
128 | rc->rc_count += number; | |
129 | count = rc->rc_count; | |
130 | mutex_exit(&rc->rc_mtx); | |
131 | ||
132 | return (count); | |
133 | } | |
134 | ||
135 | int64_t | |
136 | refcount_add(refcount_t *rc, void *holder) | |
137 | { | |
138 | return (refcount_add_many(rc, 1, holder)); | |
139 | } | |
140 | ||
141 | int64_t | |
142 | refcount_remove_many(refcount_t *rc, uint64_t number, void *holder) | |
143 | { | |
144 | reference_t *ref; | |
145 | int64_t count; | |
146 | ||
147 | mutex_enter(&rc->rc_mtx); | |
148 | ASSERT(rc->rc_count >= number); | |
149 | ||
150 | if (!reference_tracking_enable) { | |
151 | rc->rc_count -= number; | |
152 | count = rc->rc_count; | |
153 | mutex_exit(&rc->rc_mtx); | |
154 | return (count); | |
155 | } | |
156 | ||
157 | for (ref = list_head(&rc->rc_list); ref; | |
158 | ref = list_next(&rc->rc_list, ref)) { | |
159 | if (ref->ref_holder == holder && ref->ref_number == number) { | |
160 | list_remove(&rc->rc_list, ref); | |
161 | if (reference_history > 0) { | |
162 | ref->ref_removed = | |
163 | kmem_cache_alloc(reference_history_cache, | |
164 | KM_SLEEP); | |
165 | list_insert_head(&rc->rc_removed, ref); | |
166 | rc->rc_removed_count++; | |
167 | if (rc->rc_removed_count >= reference_history) { | |
168 | ref = list_tail(&rc->rc_removed); | |
169 | list_remove(&rc->rc_removed, ref); | |
170 | kmem_cache_free(reference_history_cache, | |
171 | ref->ref_removed); | |
172 | kmem_cache_free(reference_cache, ref); | |
173 | rc->rc_removed_count--; | |
174 | } | |
175 | } else { | |
176 | kmem_cache_free(reference_cache, ref); | |
177 | } | |
178 | rc->rc_count -= number; | |
179 | count = rc->rc_count; | |
180 | mutex_exit(&rc->rc_mtx); | |
181 | return (count); | |
182 | } | |
183 | } | |
184 | panic("No such hold %p on refcount %llx", holder, | |
185 | (u_longlong_t)(uintptr_t)rc); | |
186 | return (-1); | |
187 | } | |
188 | ||
189 | int64_t | |
190 | refcount_remove(refcount_t *rc, void *holder) | |
191 | { | |
192 | return (refcount_remove_many(rc, 1, holder)); | |
193 | } | |
194 | ||
195 | #endif |