1 // SPDX-License-Identifier: CDDL-1.0 2 /* 3 * CDDL HEADER START 4 * 5 * The contents of this file are subject to the terms of the 6 * Common Development and Distribution License (the "License"). 7 * You may not use this file except in compliance with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or https://opensource.org/licenses/CDDL-1.0. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 28 29 #include <sys/zfs_context.h> 30 #include <sys/avl.h> 31 #include <sys/unique.h> 32 33 static avl_tree_t unique_avl; 34 static kmutex_t unique_mtx; 35 36 typedef struct unique { 37 avl_node_t un_link; 38 uint64_t un_value; 39 } unique_t; 40 41 #define UNIQUE_MASK ((1ULL << UNIQUE_BITS) - 1) 42 43 static int 44 unique_compare(const void *a, const void *b) 45 { 46 const unique_t *una = (const unique_t *)a; 47 const unique_t *unb = (const unique_t *)b; 48 49 return (TREE_CMP(una->un_value, unb->un_value)); 50 } 51 52 void 53 unique_init(void) 54 { 55 avl_create(&unique_avl, unique_compare, 56 sizeof (unique_t), offsetof(unique_t, un_link)); 57 mutex_init(&unique_mtx, NULL, MUTEX_DEFAULT, NULL); 58 } 59 60 void 61 unique_fini(void) 62 { 63 avl_destroy(&unique_avl); 64 mutex_destroy(&unique_mtx); 65 } 66 67 uint64_t 68 unique_create(void) 69 { 70 uint64_t value = unique_insert(0); 71 unique_remove(value); 72 return (value); 73 } 74 75 uint64_t 76 unique_insert(uint64_t value) 77 { 78 avl_index_t idx; 79 unique_t *un = kmem_alloc(sizeof (unique_t), KM_SLEEP); 80 81 un->un_value = value; 82 83 mutex_enter(&unique_mtx); 84 while (un->un_value == 0 || un->un_value & ~UNIQUE_MASK || 85 avl_find(&unique_avl, un, &idx)) { 86 mutex_exit(&unique_mtx); 87 (void) random_get_pseudo_bytes((void*)&un->un_value, 88 sizeof (un->un_value)); 89 un->un_value &= UNIQUE_MASK; 90 mutex_enter(&unique_mtx); 91 } 92 93 avl_insert(&unique_avl, un, idx); 94 mutex_exit(&unique_mtx); 95 96 return (un->un_value); 97 } 98 99 void 100 unique_remove(uint64_t value) 101 { 102 unique_t un_tofind; 103 unique_t *un; 104 105 un_tofind.un_value = value; 106 mutex_enter(&unique_mtx); 107 un = avl_find(&unique_avl, &un_tofind, NULL); 108 if (un != NULL) { 109 avl_remove(&unique_avl, un); 110 kmem_free(un, sizeof (unique_t)); 111 } 112 mutex_exit(&unique_mtx); 113 } 114