Revision a3384067fb0df9c58e112ac6a5ec9beb7d169482 authored by Stefan Richter on 16 August 2008, 11:39:26 UTC, committed by Stefan Richter on 19 August 2008, 16:47:56 UTC
sbp2 was too quick to report .update() to the ieee1394 core as failed. (Logged as "Failed to reconnect to sbp2 device!".) The core would then unbind sbp2 from the device. This is not justified if the .update() failed because another bus reset happened. We check this and tell the ieee1394 that .update() succeeded, and the core will call sbp2's .update() for the new bus reset as well. This improves reconnection/re-login especially on buses with several disks as they may issue bus resets in close succession when they come online. Tested by Damien Benoist. Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
1 parent c921a97
random32.c
/*
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.
*/
#include <linux/types.h>
#include <linux/percpu.h>
#include <linux/module.h>
#include <linux/jiffies.h>
#include <linux/random.h>
struct rnd_state {
u32 s1, s2, s3;
};
static DEFINE_PER_CPU(struct rnd_state, net_rand_state);
static u32 __random32(struct rnd_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);
}
/*
* Handle minimum values for seeds
*/
static inline u32 __seed(u32 x, u32 m)
{
return (x < m) ? x + m : x;
}
/**
* random32 - pseudo random number generator
*
* A 32 bit pseudo-random number is generated using a fast
* algorithm suitable for simulation. This algorithm is NOT
* considered safe for cryptographic use.
*/
u32 random32(void)
{
unsigned long r;
struct rnd_state *state = &get_cpu_var(net_rand_state);
r = __random32(state);
put_cpu_var(state);
return r;
}
EXPORT_SYMBOL(random32);
/**
* srandom32 - add entropy to pseudo random number generator
* @seed: seed value
*
* Add some additional seeding to the random32() pool.
*/
void srandom32(u32 entropy)
{
int i;
/*
* No locking on the CPUs, but then somewhat random results are, well,
* expected.
*/
for_each_possible_cpu (i) {
struct rnd_state *state = &per_cpu(net_rand_state, i);
state->s1 = __seed(state->s1 ^ entropy, 1);
}
}
EXPORT_SYMBOL(srandom32);
/*
* Generate some initially weak seeding values to allow
* to start the random32() engine.
*/
static int __init random32_init(void)
{
int i;
for_each_possible_cpu(i) {
struct rnd_state *state = &per_cpu(net_rand_state,i);
#define LCG(x) ((x) * 69069) /* super-duper LCG */
state->s1 = __seed(LCG(i + jiffies), 1);
state->s2 = __seed(LCG(state->s1), 7);
state->s3 = __seed(LCG(state->s2), 15);
/* "warm it up" */
__random32(state);
__random32(state);
__random32(state);
__random32(state);
__random32(state);
__random32(state);
}
return 0;
}
core_initcall(random32_init);
/*
* Generate better values after random number generator
* is fully initalized.
*/
static int __init random32_reseed(void)
{
int i;
for_each_possible_cpu(i) {
struct rnd_state *state = &per_cpu(net_rand_state,i);
u32 seeds[3];
get_random_bytes(&seeds, sizeof(seeds));
state->s1 = __seed(seeds[0], 1);
state->s2 = __seed(seeds[1], 7);
state->s3 = __seed(seeds[2], 15);
/* mix it in */
__random32(state);
}
return 0;
}
late_initcall(random32_reseed);
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