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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
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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+/*
+ * Generic address resultion entity
+ *
+ * Authors:
+ * net_random Alan Cox
+ * net_ratelimit Andy Kleen
+ *
+ * Created by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/random.h>
+#include <linux/percpu.h>
+#include <linux/init.h>
+
+#include <asm/system.h>
+#include <asm/uaccess.h>
+
+
+/*
+ This is a maximally equidistributed combined Tausworthe generator
+ based on code from GNU Scientific Library 1.5 (30 Jun 2004)
+
+ x_n = (s1_n ^ s2_n ^ s3_n)
+
+ s1_{n+1} = (((s1_n & 4294967294) <<12) ^ (((s1_n <<13) ^ s1_n) >>19))
+ s2_{n+1} = (((s2_n & 4294967288) << 4) ^ (((s2_n << 2) ^ s2_n) >>25))
+ s3_{n+1} = (((s3_n & 4294967280) <<17) ^ (((s3_n << 3) ^ s3_n) >>11))
+
+ The period of this generator is about 2^88.
+
+ From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
+ Generators", Mathematics of Computation, 65, 213 (1996), 203--213.
+
+ This is available on the net from L'Ecuyer's home page,
+
+ http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
+ ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
+
+ There is an erratum in the paper "Tables of Maximally
+ Equidistributed Combined LFSR Generators", Mathematics of
+ Computation, 68, 225 (1999), 261--269:
+ http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
+
+ ... the k_j most significant bits of z_j must be non-
+ zero, for each j. (Note: this restriction also applies to the
+ computer code given in [4], but was mistakenly not mentioned in
+ that paper.)
+
+ This affects the seeding procedure by imposing the requirement
+ s1 > 1, s2 > 7, s3 > 15.
+
+*/
+struct nrnd_state {
+ u32 s1, s2, s3;
+};
+
+static DEFINE_PER_CPU(struct nrnd_state, net_rand_state);
+
+static u32 __net_random(struct nrnd_state *state)
+{
+#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b)
+
+ state->s1 = TAUSWORTHE(state->s1, 13, 19, 4294967294UL, 12);
+ state->s2 = TAUSWORTHE(state->s2, 2, 25, 4294967288UL, 4);
+ state->s3 = TAUSWORTHE(state->s3, 3, 11, 4294967280UL, 17);
+
+ return (state->s1 ^ state->s2 ^ state->s3);
+}
+
+static void __net_srandom(struct nrnd_state *state, unsigned long s)
+{
+ if (s == 0)
+ s = 1; /* default seed is 1 */
+
+#define LCG(n) (69069 * n)
+ state->s1 = LCG(s);
+ state->s2 = LCG(state->s1);
+ state->s3 = LCG(state->s2);
+
+ /* "warm it up" */
+ __net_random(state);
+ __net_random(state);
+ __net_random(state);
+ __net_random(state);
+ __net_random(state);
+ __net_random(state);
+}
+
+
+unsigned long net_random(void)
+{
+ unsigned long r;
+ struct nrnd_state *state = &get_cpu_var(net_rand_state);
+ r = __net_random(state);
+ put_cpu_var(state);
+ return r;
+}
+
+
+void net_srandom(unsigned long entropy)
+{
+ struct nrnd_state *state = &get_cpu_var(net_rand_state);
+ __net_srandom(state, state->s1^entropy);
+ put_cpu_var(state);
+}
+
+void __init net_random_init(void)
+{
+ int i;
+
+ for (i = 0; i < NR_CPUS; i++) {
+ struct nrnd_state *state = &per_cpu(net_rand_state,i);
+ __net_srandom(state, i+jiffies);
+ }
+}
+
+static int net_random_reseed(void)
+{
+ int i;
+ unsigned long seed[NR_CPUS];
+
+ get_random_bytes(seed, sizeof(seed));
+ for (i = 0; i < NR_CPUS; i++) {
+ struct nrnd_state *state = &per_cpu(net_rand_state,i);
+ __net_srandom(state, seed[i]);
+ }
+ return 0;
+}
+late_initcall(net_random_reseed);
+
+int net_msg_cost = 5*HZ;
+int net_msg_burst = 10;
+
+/*
+ * All net warning printk()s should be guarded by this function.
+ */
+int net_ratelimit(void)
+{
+ return __printk_ratelimit(net_msg_cost, net_msg_burst);
+}
+
+EXPORT_SYMBOL(net_random);
+EXPORT_SYMBOL(net_ratelimit);
+EXPORT_SYMBOL(net_srandom);