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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /net/core/utils.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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1/*
2 * Generic address resultion entity
3 *
4 * Authors:
5 * net_random Alan Cox
6 * net_ratelimit Andy Kleen
7 *
8 * Created by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 */
15
16#include <linux/module.h>
17#include <linux/jiffies.h>
18#include <linux/kernel.h>
19#include <linux/mm.h>
20#include <linux/string.h>
21#include <linux/types.h>
22#include <linux/random.h>
23#include <linux/percpu.h>
24#include <linux/init.h>
25
26#include <asm/system.h>
27#include <asm/uaccess.h>
28
29
30/*
31 This is a maximally equidistributed combined Tausworthe generator
32 based on code from GNU Scientific Library 1.5 (30 Jun 2004)
33
34 x_n = (s1_n ^ s2_n ^ s3_n)
35
36 s1_{n+1} = (((s1_n & 4294967294) <<12) ^ (((s1_n <<13) ^ s1_n) >>19))
37 s2_{n+1} = (((s2_n & 4294967288) << 4) ^ (((s2_n << 2) ^ s2_n) >>25))
38 s3_{n+1} = (((s3_n & 4294967280) <<17) ^ (((s3_n << 3) ^ s3_n) >>11))
39
40 The period of this generator is about 2^88.
41
42 From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
43 Generators", Mathematics of Computation, 65, 213 (1996), 203--213.
44
45 This is available on the net from L'Ecuyer's home page,
46
47 http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
48 ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
49
50 There is an erratum in the paper "Tables of Maximally
51 Equidistributed Combined LFSR Generators", Mathematics of
52 Computation, 68, 225 (1999), 261--269:
53 http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
54
55 ... the k_j most significant bits of z_j must be non-
56 zero, for each j. (Note: this restriction also applies to the
57 computer code given in [4], but was mistakenly not mentioned in
58 that paper.)
59
60 This affects the seeding procedure by imposing the requirement
61 s1 > 1, s2 > 7, s3 > 15.
62
63*/
64struct nrnd_state {
65 u32 s1, s2, s3;
66};
67
68static DEFINE_PER_CPU(struct nrnd_state, net_rand_state);
69
70static u32 __net_random(struct nrnd_state *state)
71{
72#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b)
73
74 state->s1 = TAUSWORTHE(state->s1, 13, 19, 4294967294UL, 12);
75 state->s2 = TAUSWORTHE(state->s2, 2, 25, 4294967288UL, 4);
76 state->s3 = TAUSWORTHE(state->s3, 3, 11, 4294967280UL, 17);
77
78 return (state->s1 ^ state->s2 ^ state->s3);
79}
80
81static void __net_srandom(struct nrnd_state *state, unsigned long s)
82{
83 if (s == 0)
84 s = 1; /* default seed is 1 */
85
86#define LCG(n) (69069 * n)
87 state->s1 = LCG(s);
88 state->s2 = LCG(state->s1);
89 state->s3 = LCG(state->s2);
90
91 /* "warm it up" */
92 __net_random(state);
93 __net_random(state);
94 __net_random(state);
95 __net_random(state);
96 __net_random(state);
97 __net_random(state);
98}
99
100
101unsigned long net_random(void)
102{
103 unsigned long r;
104 struct nrnd_state *state = &get_cpu_var(net_rand_state);
105 r = __net_random(state);
106 put_cpu_var(state);
107 return r;
108}
109
110
111void net_srandom(unsigned long entropy)
112{
113 struct nrnd_state *state = &get_cpu_var(net_rand_state);
114 __net_srandom(state, state->s1^entropy);
115 put_cpu_var(state);
116}
117
118void __init net_random_init(void)
119{
120 int i;
121
122 for (i = 0; i < NR_CPUS; i++) {
123 struct nrnd_state *state = &per_cpu(net_rand_state,i);
124 __net_srandom(state, i+jiffies);
125 }
126}
127
128static int net_random_reseed(void)
129{
130 int i;
131 unsigned long seed[NR_CPUS];
132
133 get_random_bytes(seed, sizeof(seed));
134 for (i = 0; i < NR_CPUS; i++) {
135 struct nrnd_state *state = &per_cpu(net_rand_state,i);
136 __net_srandom(state, seed[i]);
137 }
138 return 0;
139}
140late_initcall(net_random_reseed);
141
142int net_msg_cost = 5*HZ;
143int net_msg_burst = 10;
144
145/*
146 * All net warning printk()s should be guarded by this function.
147 */
148int net_ratelimit(void)
149{
150 return __printk_ratelimit(net_msg_cost, net_msg_burst);
151}
152
153EXPORT_SYMBOL(net_random);
154EXPORT_SYMBOL(net_ratelimit);
155EXPORT_SYMBOL(net_srandom);