| 1 | /* $NetBSD: subr_hash.c,v 1.7 2016/07/06 05:20:48 ozaki-r Exp $ */ |
| 2 | |
| 3 | /* |
| 4 | * Copyright (c) 1982, 1986, 1991, 1993 |
| 5 | * The Regents of the University of California. All rights reserved. |
| 6 | * (c) UNIX System Laboratories, Inc. |
| 7 | * All or some portions of this file are derived from material licensed |
| 8 | * to the University of California by American Telephone and Telegraph |
| 9 | * Co. or Unix System Laboratories, Inc. and are reproduced herein with |
| 10 | * the permission of UNIX System Laboratories, Inc. |
| 11 | * |
| 12 | * Redistribution and use in source and binary forms, with or without |
| 13 | * modification, are permitted provided that the following conditions |
| 14 | * are met: |
| 15 | * 1. Redistributions of source code must retain the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer. |
| 17 | * 2. Redistributions in binary form must reproduce the above copyright |
| 18 | * notice, this list of conditions and the following disclaimer in the |
| 19 | * documentation and/or other materials provided with the distribution. |
| 20 | * 3. Neither the name of the University nor the names of its contributors |
| 21 | * may be used to endorse or promote products derived from this software |
| 22 | * without specific prior written permission. |
| 23 | * |
| 24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 34 | * SUCH DAMAGE. |
| 35 | * |
| 36 | * @(#)kern_subr.c 8.4 (Berkeley) 2/14/95 |
| 37 | */ |
| 38 | |
| 39 | #include <sys/cdefs.h> |
| 40 | __KERNEL_RCSID(0, "$NetBSD: subr_hash.c,v 1.7 2016/07/06 05:20:48 ozaki-r Exp $" ); |
| 41 | |
| 42 | #include <sys/param.h> |
| 43 | #include <sys/bitops.h> |
| 44 | #include <sys/kmem.h> |
| 45 | #include <sys/systm.h> |
| 46 | #include <sys/pslist.h> |
| 47 | |
| 48 | static size_t |
| 49 | hash_list_size(enum hashtype htype) |
| 50 | { |
| 51 | LIST_HEAD(, generic) *hashtbl_list; |
| 52 | SLIST_HEAD(, generic) *hashtbl_slist; |
| 53 | TAILQ_HEAD(, generic) *hashtbl_tailq; |
| 54 | struct pslist_head *hashtbl_pslist; |
| 55 | size_t esize; |
| 56 | |
| 57 | switch (htype) { |
| 58 | case HASH_LIST: |
| 59 | esize = sizeof(*hashtbl_list); |
| 60 | break; |
| 61 | case HASH_PSLIST: |
| 62 | esize = sizeof(*hashtbl_pslist); |
| 63 | break; |
| 64 | case HASH_SLIST: |
| 65 | esize = sizeof(*hashtbl_slist); |
| 66 | break; |
| 67 | case HASH_TAILQ: |
| 68 | esize = sizeof(*hashtbl_tailq); |
| 69 | break; |
| 70 | default: |
| 71 | panic("hashdone: invalid table type" ); |
| 72 | } |
| 73 | return esize; |
| 74 | } |
| 75 | |
| 76 | /* |
| 77 | * General routine to allocate a hash table. |
| 78 | * Allocate enough memory to hold at least `elements' list-head pointers. |
| 79 | * Return a pointer to the allocated space and set *hashmask to a pattern |
| 80 | * suitable for masking a value to use as an index into the returned array. |
| 81 | */ |
| 82 | void * |
| 83 | hashinit(u_int elements, enum hashtype htype, bool waitok, u_long *hashmask) |
| 84 | { |
| 85 | LIST_HEAD(, generic) *hashtbl_list; |
| 86 | SLIST_HEAD(, generic) *hashtbl_slist; |
| 87 | TAILQ_HEAD(, generic) *hashtbl_tailq; |
| 88 | struct pslist_head *hashtbl_pslist; |
| 89 | u_long hashsize, i; |
| 90 | size_t esize; |
| 91 | void *p; |
| 92 | |
| 93 | KASSERT(elements > 0); |
| 94 | |
| 95 | #define MAXELEMENTS (1U << ((sizeof(elements) * NBBY) - 1)) |
| 96 | if (elements > MAXELEMENTS) |
| 97 | elements = MAXELEMENTS; |
| 98 | |
| 99 | hashsize = 1UL << (ilog2(elements - 1) + 1); |
| 100 | esize = hash_list_size(htype); |
| 101 | |
| 102 | p = kmem_alloc(hashsize * esize, waitok ? KM_SLEEP : KM_NOSLEEP); |
| 103 | if (p == NULL) |
| 104 | return NULL; |
| 105 | |
| 106 | switch (htype) { |
| 107 | case HASH_LIST: |
| 108 | hashtbl_list = p; |
| 109 | for (i = 0; i < hashsize; i++) |
| 110 | LIST_INIT(&hashtbl_list[i]); |
| 111 | break; |
| 112 | case HASH_PSLIST: |
| 113 | hashtbl_pslist = p; |
| 114 | for (i = 0; i < hashsize; i++) |
| 115 | PSLIST_INIT(&hashtbl_pslist[i]); |
| 116 | break; |
| 117 | case HASH_SLIST: |
| 118 | hashtbl_slist = p; |
| 119 | for (i = 0; i < hashsize; i++) |
| 120 | SLIST_INIT(&hashtbl_slist[i]); |
| 121 | break; |
| 122 | case HASH_TAILQ: |
| 123 | hashtbl_tailq = p; |
| 124 | for (i = 0; i < hashsize; i++) |
| 125 | TAILQ_INIT(&hashtbl_tailq[i]); |
| 126 | break; |
| 127 | } |
| 128 | *hashmask = hashsize - 1; |
| 129 | return p; |
| 130 | } |
| 131 | |
| 132 | /* |
| 133 | * Free memory from hash table previosly allocated via hashinit(). |
| 134 | */ |
| 135 | void |
| 136 | hashdone(void *hashtbl, enum hashtype htype, u_long hashmask) |
| 137 | { |
| 138 | const size_t esize = hash_list_size(htype); |
| 139 | kmem_free(hashtbl, esize * (hashmask + 1)); |
| 140 | } |
| 141 | |