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 */ 24 25 #include <sys/zfs_context.h> 26 #include <sys/refcount.h> 27 28 #ifdef ZFS_DEBUG 29 30 #ifdef _KERNEL 31 int reference_tracking_enable = FALSE; /* runs out of memory too easily */ 32 #else 33 int reference_tracking_enable = TRUE; 34 #endif 35 int reference_history = 4; /* tunable */ 36 37 static kmem_cache_t *reference_cache; 38 static kmem_cache_t *reference_history_cache; 39 40 void 41 refcount_init(void) 42 { 43 reference_cache = kmem_cache_create("reference_cache", 44 sizeof (reference_t), 0, NULL, NULL, NULL, NULL, NULL, 0); 45 46 reference_history_cache = kmem_cache_create("reference_history_cache", 47 sizeof (uint64_t), 0, NULL, NULL, NULL, NULL, NULL, 0); 48 } 49 50 void 51 refcount_fini(void) 52 { 53 kmem_cache_destroy(reference_cache); 54 kmem_cache_destroy(reference_history_cache); 55 } 56 57 void 58 refcount_create(refcount_t *rc) 59 { 60 mutex_init(&rc->rc_mtx, NULL, MUTEX_DEFAULT, NULL); 61 list_create(&rc->rc_list, sizeof (reference_t), 62 offsetof(reference_t, ref_link)); 63 list_create(&rc->rc_removed, sizeof (reference_t), 64 offsetof(reference_t, ref_link)); 65 rc->rc_count = 0; 66 rc->rc_removed_count = 0; 67 } 68 69 void 70 refcount_destroy_many(refcount_t *rc, uint64_t number) 71 { 72 reference_t *ref; 73 74 ASSERT(rc->rc_count == number); 75 while (ref = list_head(&rc->rc_list)) { 76 list_remove(&rc->rc_list, ref); 77 kmem_cache_free(reference_cache, ref); 78 } 79 list_destroy(&rc->rc_list); 80 81 while (ref = list_head(&rc->rc_removed)) { 82 list_remove(&rc->rc_removed, ref); 83 kmem_cache_free(reference_history_cache, ref->ref_removed); 84 kmem_cache_free(reference_cache, ref); 85 } 86 list_destroy(&rc->rc_removed); 87 mutex_destroy(&rc->rc_mtx); 88 } 89 90 void 91 refcount_destroy(refcount_t *rc) 92 { 93 refcount_destroy_many(rc, 0); 94 } 95 96 int 97 refcount_is_zero(refcount_t *rc) 98 { 99 ASSERT(rc->rc_count >= 0); 100 return (rc->rc_count == 0); 101 } 102 103 int64_t 104 refcount_count(refcount_t *rc) 105 { 106 ASSERT(rc->rc_count >= 0); 107 return (rc->rc_count); 108 } 109 110 int64_t 111 refcount_add_many(refcount_t *rc, uint64_t number, void *holder) 112 { 113 reference_t *ref; 114 int64_t count; 115 116 if (reference_tracking_enable) { 117 ref = kmem_cache_alloc(reference_cache, KM_SLEEP); 118 ref->ref_holder = holder; 119 ref->ref_number = number; 120 } 121 mutex_enter(&rc->rc_mtx); 122 ASSERT(rc->rc_count >= 0); 123 if (reference_tracking_enable) 124 list_insert_head(&rc->rc_list, ref); 125 rc->rc_count += number; 126 count = rc->rc_count; 127 mutex_exit(&rc->rc_mtx); 128 129 return (count); 130 } 131 132 int64_t 133 refcount_add(refcount_t *rc, void *holder) 134 { 135 return (refcount_add_many(rc, 1, holder)); 136 } 137 138 int64_t 139 refcount_remove_many(refcount_t *rc, uint64_t number, void *holder) 140 { 141 reference_t *ref; 142 int64_t count; 143 144 mutex_enter(&rc->rc_mtx); 145 ASSERT(rc->rc_count >= number); 146 147 if (!reference_tracking_enable) { 148 rc->rc_count -= number; 149 count = rc->rc_count; 150 mutex_exit(&rc->rc_mtx); 151 return (count); 152 } 153 154 for (ref = list_head(&rc->rc_list); ref; 155 ref = list_next(&rc->rc_list, ref)) { 156 if (ref->ref_holder == holder && ref->ref_number == number) { 157 list_remove(&rc->rc_list, ref); 158 if (reference_history > 0) { 159 ref->ref_removed = 160 kmem_cache_alloc(reference_history_cache, 161 KM_SLEEP); 162 list_insert_head(&rc->rc_removed, ref); 163 rc->rc_removed_count++; 164 if (rc->rc_removed_count >= reference_history) { 165 ref = list_tail(&rc->rc_removed); 166 list_remove(&rc->rc_removed, ref); 167 kmem_cache_free(reference_history_cache, 168 ref->ref_removed); 169 kmem_cache_free(reference_cache, ref); 170 rc->rc_removed_count--; 171 } 172 } else { 173 kmem_cache_free(reference_cache, ref); 174 } 175 rc->rc_count -= number; 176 count = rc->rc_count; 177 mutex_exit(&rc->rc_mtx); 178 return (count); 179 } 180 } 181 panic("No such hold %p on refcount %llx", holder, 182 (u_longlong_t)(uintptr_t)rc); 183 return (-1); 184 } 185 186 int64_t 187 refcount_remove(refcount_t *rc, void *holder) 188 { 189 return (refcount_remove_many(rc, 1, holder)); 190 } 191 192 void 193 refcount_transfer(refcount_t *dst, refcount_t *src) 194 { 195 int64_t count, removed_count; 196 list_t list, removed; 197 198 list_create(&list, sizeof (reference_t), 199 offsetof(reference_t, ref_link)); 200 list_create(&removed, sizeof (reference_t), 201 offsetof(reference_t, ref_link)); 202 203 mutex_enter(&src->rc_mtx); 204 count = src->rc_count; 205 removed_count = src->rc_removed_count; 206 src->rc_count = 0; 207 src->rc_removed_count = 0; 208 list_move_tail(&list, &src->rc_list); 209 list_move_tail(&removed, &src->rc_removed); 210 mutex_exit(&src->rc_mtx); 211 212 mutex_enter(&dst->rc_mtx); 213 dst->rc_count += count; 214 dst->rc_removed_count += removed_count; 215 list_move_tail(&dst->rc_list, &list); 216 list_move_tail(&dst->rc_removed, &removed); 217 mutex_exit(&dst->rc_mtx); 218 219 list_destroy(&list); 220 list_destroy(&removed); 221 } 222 223 #endif /* ZFS_DEBUG */ 224