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.
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.
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]
22 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
26 #pragma ident "%Z%%M% %I% %E% SMI"
28 #include <sys/zfs_context.h>
30 #include <sys/unique.h>
32 static avl_tree_t unique_avl;
33 static kmutex_t unique_mtx; /* Lock never initialized. */
34 SX_SYSINIT(unique, &unique_mtx, "unique lock");
36 typedef struct unique {
41 #define UNIQUE_MASK ((1ULL << UNIQUE_BITS) - 1)
44 unique_compare(const void *a, const void *b)
46 const unique_t *una = a;
47 const unique_t *unb = b;
49 if (una->un_value < unb->un_value)
51 if (una->un_value > unb->un_value)
59 avl_create(&unique_avl, unique_compare,
60 sizeof (unique_t), offsetof(unique_t, un_link));
66 return (unique_insert(0));
70 unique_insert(uint64_t value)
73 unique_t *un = kmem_alloc(sizeof (unique_t), KM_SLEEP);
77 mutex_enter(&unique_mtx);
78 while (un->un_value == 0 || un->un_value & ~UNIQUE_MASK ||
79 avl_find(&unique_avl, un, &idx)) {
80 mutex_exit(&unique_mtx);
81 (void) random_get_pseudo_bytes((void*)&un->un_value,
82 sizeof (un->un_value));
83 un->un_value &= UNIQUE_MASK;
84 mutex_enter(&unique_mtx);
87 avl_insert(&unique_avl, un, idx);
88 mutex_exit(&unique_mtx);
90 return (un->un_value);
94 unique_remove(uint64_t value)
99 un_tofind.un_value = value;
100 mutex_enter(&unique_mtx);
101 un = avl_find(&unique_avl, &un_tofind, NULL);
103 avl_remove(&unique_avl, un);
104 kmem_free(un, sizeof (unique_t));
106 mutex_exit(&unique_mtx);