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 196