diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /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!
Diffstat (limited to 'net/core/utils.c')
-rw-r--r-- | net/core/utils.c | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/net/core/utils.c b/net/core/utils.c new file mode 100644 index 000000000000..e11a8654f363 --- /dev/null +++ b/net/core/utils.c | |||
@@ -0,0 +1,155 @@ | |||
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 | */ | ||
64 | struct nrnd_state { | ||
65 | u32 s1, s2, s3; | ||
66 | }; | ||
67 | |||
68 | static DEFINE_PER_CPU(struct nrnd_state, net_rand_state); | ||
69 | |||
70 | static 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 | |||
81 | static 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 | |||
101 | unsigned 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 | |||
111 | void 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 | |||
118 | void __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 | |||
128 | static 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 | } | ||
140 | late_initcall(net_random_reseed); | ||
141 | |||
142 | int net_msg_cost = 5*HZ; | ||
143 | int net_msg_burst = 10; | ||
144 | |||
145 | /* | ||
146 | * All net warning printk()s should be guarded by this function. | ||
147 | */ | ||
148 | int net_ratelimit(void) | ||
149 | { | ||
150 | return __printk_ratelimit(net_msg_cost, net_msg_burst); | ||
151 | } | ||
152 | |||
153 | EXPORT_SYMBOL(net_random); | ||
154 | EXPORT_SYMBOL(net_ratelimit); | ||
155 | EXPORT_SYMBOL(net_srandom); | ||