subr_hash.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 * 4. 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	8.3 (Berkeley) 1/21/94
37 */
38
39#include <sys/cdefs.h>
40__FBSDID("$FreeBSD: stable/11/sys/kern/subr_hash.c 330897 2018-03-14 03:19:51Z eadler $");
41
42#include <sys/param.h>
43#include <sys/systm.h>
44#include <sys/malloc.h>
45
46static __inline int
47hash_mflags(int flags)
48{
49
50	return ((flags & HASH_NOWAIT) ? M_NOWAIT : M_WAITOK);
51}
52
53/*
54 * General routine to allocate a hash table with control of memory flags.
55 */
56void *
57hashinit_flags(int elements, struct malloc_type *type, u_long *hashmask,
58    int flags)
59{
60	long hashsize;
61	LIST_HEAD(generic, generic) *hashtbl;
62	int i;
63
64	KASSERT(elements > 0, ("%s: bad elements", __func__));
65	/* Exactly one of HASH_WAITOK and HASH_NOWAIT must be set. */
66	KASSERT((flags & HASH_WAITOK) ^ (flags & HASH_NOWAIT),
67	    ("Bad flags (0x%x) passed to hashinit_flags", flags));
68
69	for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
70		continue;
71	hashsize >>= 1;
72
73	hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type,
74	    hash_mflags(flags));
75	if (hashtbl != NULL) {
76		for (i = 0; i < hashsize; i++)
77			LIST_INIT(&hashtbl[i]);
78		*hashmask = hashsize - 1;
79	}
80	return (hashtbl);
81}
82
83/*
84 * Allocate and initialize a hash table with default flag: may sleep.
85 */
86void *
87hashinit(int elements, struct malloc_type *type, u_long *hashmask)
88{
89
90	return (hashinit_flags(elements, type, hashmask, HASH_WAITOK));
91}
92
93void
94hashdestroy(void *vhashtbl, struct malloc_type *type, u_long hashmask)
95{
96	LIST_HEAD(generic, generic) *hashtbl, *hp;
97
98	hashtbl = vhashtbl;
99	for (hp = hashtbl; hp <= &hashtbl[hashmask]; hp++)
100		KASSERT(LIST_EMPTY(hp), ("%s: hashtbl %p not empty "
101		    "(malloc type %s)", __func__, hashtbl, type->ks_shortdesc));
102	free(hashtbl, type);
103}
104
105static const int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531,
106			2039, 2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143,
107			6653, 7159, 7673, 8191, 12281, 16381, 24571, 32749 };
108#define	NPRIMES nitems(primes)
109
110/*
111 * General routine to allocate a prime number sized hash table with control of
112 * memory flags.
113 */
114void *
115phashinit_flags(int elements, struct malloc_type *type, u_long *nentries, int flags)
116{
117	long hashsize;
118	LIST_HEAD(generic, generic) *hashtbl;
119	int i;
120
121	KASSERT(elements > 0, ("%s: bad elements", __func__));
122	/* Exactly one of HASH_WAITOK and HASH_NOWAIT must be set. */
123	KASSERT((flags & HASH_WAITOK) ^ (flags & HASH_NOWAIT),
124	    ("Bad flags (0x%x) passed to phashinit_flags", flags));
125
126	for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
127		i++;
128		if (i == NPRIMES)
129			break;
130		hashsize = primes[i];
131	}
132	hashsize = primes[i - 1];
133
134	hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type,
135	    hash_mflags(flags));
136	if (hashtbl == NULL)
137		return (NULL);
138
139	for (i = 0; i < hashsize; i++)
140		LIST_INIT(&hashtbl[i]);
141	*nentries = hashsize;
142	return (hashtbl);
143}
144
145/*
146 * Allocate and initialize a prime number sized hash table with default flag:
147 * may sleep.
148 */
149void *
150phashinit(int elements, struct malloc_type *type, u_long *nentries)
151{
152
153	return (phashinit_flags(elements, type, nentries, HASH_WAITOK));
154}
155