FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_hash.c
1 /*-
2 * Copyright (c) 1982, 1986, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
35 */
36
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD: releng/11.2/sys/kern/subr_hash.c 331722 2018-03-29 02:50:57Z eadler $");
39
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/malloc.h>
43
44 static __inline int
45 hash_mflags(int flags)
46 {
47
48 return ((flags & HASH_NOWAIT) ? M_NOWAIT : M_WAITOK);
49 }
50
51 /*
52 * General routine to allocate a hash table with control of memory flags.
53 */
54 void *
55 hashinit_flags(int elements, struct malloc_type *type, u_long *hashmask,
56 int flags)
57 {
58 long hashsize;
59 LIST_HEAD(generic, generic) *hashtbl;
60 int i;
61
62 KASSERT(elements > 0, ("%s: bad elements", __func__));
63 /* Exactly one of HASH_WAITOK and HASH_NOWAIT must be set. */
64 KASSERT((flags & HASH_WAITOK) ^ (flags & HASH_NOWAIT),
65 ("Bad flags (0x%x) passed to hashinit_flags", flags));
66
67 for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
68 continue;
69 hashsize >>= 1;
70
71 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type,
72 hash_mflags(flags));
73 if (hashtbl != NULL) {
74 for (i = 0; i < hashsize; i++)
75 LIST_INIT(&hashtbl[i]);
76 *hashmask = hashsize - 1;
77 }
78 return (hashtbl);
79 }
80
81 /*
82 * Allocate and initialize a hash table with default flag: may sleep.
83 */
84 void *
85 hashinit(int elements, struct malloc_type *type, u_long *hashmask)
86 {
87
88 return (hashinit_flags(elements, type, hashmask, HASH_WAITOK));
89 }
90
91 void
92 hashdestroy(void *vhashtbl, struct malloc_type *type, u_long hashmask)
93 {
94 LIST_HEAD(generic, generic) *hashtbl, *hp;
95
96 hashtbl = vhashtbl;
97 for (hp = hashtbl; hp <= &hashtbl[hashmask]; hp++)
98 KASSERT(LIST_EMPTY(hp), ("%s: hashtbl %p not empty "
99 "(malloc type %s)", __func__, hashtbl, type->ks_shortdesc));
100 free(hashtbl, type);
101 }
102
103 static const int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531,
104 2039, 2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143,
105 6653, 7159, 7673, 8191, 12281, 16381, 24571, 32749 };
106 #define NPRIMES nitems(primes)
107
108 /*
109 * General routine to allocate a prime number sized hash table with control of
110 * memory flags.
111 */
112 void *
113 phashinit_flags(int elements, struct malloc_type *type, u_long *nentries, int flags)
114 {
115 long hashsize;
116 LIST_HEAD(generic, generic) *hashtbl;
117 int i;
118
119 KASSERT(elements > 0, ("%s: bad elements", __func__));
120 /* Exactly one of HASH_WAITOK and HASH_NOWAIT must be set. */
121 KASSERT((flags & HASH_WAITOK) ^ (flags & HASH_NOWAIT),
122 ("Bad flags (0x%x) passed to phashinit_flags", flags));
123
124 for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
125 i++;
126 if (i == NPRIMES)
127 break;
128 hashsize = primes[i];
129 }
130 hashsize = primes[i - 1];
131
132 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type,
133 hash_mflags(flags));
134 if (hashtbl == NULL)
135 return (NULL);
136
137 for (i = 0; i < hashsize; i++)
138 LIST_INIT(&hashtbl[i]);
139 *nentries = hashsize;
140 return (hashtbl);
141 }
142
143 /*
144 * Allocate and initialize a prime number sized hash table with default flag:
145 * may sleep.
146 */
147 void *
148 phashinit(int elements, struct malloc_type *type, u_long *nentries)
149 {
150
151 return (phashinit_flags(elements, type, nentries, HASH_WAITOK));
152 }
Cache object: fa284b9ed5f1bfd198f25d5a19f0b8a7
|