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random: Make thread-safe.

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Signed-off-by: Ben Pfaff <blp@nicira.com>
This commit is contained in:
Ben Pfaff
2013-06-25 13:53:36 -07:00
parent 10a89ef04d
commit 61d71ceb5d
1 changed files with 17 additions and 9 deletions
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26
lib/random.c
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -22,6 +22,8 @@
#include <sys/time.h>
#include "entropy.h"
#include "hash.h"
#include "ovs-thread.h"
#include "timeval.h"
#include "util.h"
@@ -37,21 +39,25 @@
* cryptographic-quality randomness. */
/* Current random state. */
static uint32_t seed;
DEFINE_PER_THREAD_DATA(uint32_t, seed, 0);
static uint32_t random_next(void);
void
random_init(void)
{
while (!seed) {
uint32_t *seedp = seed_get();
while (!*seedp) {
struct timeval tv;
uint32_t entropy;
pthread_t self;
xgettimeofday(&tv);
get_entropy_or_die(&entropy, 4);
self = pthread_self();
seed = tv.tv_sec ^ tv.tv_usec ^ entropy;
*seedp = (tv.tv_sec ^ tv.tv_usec ^ entropy
^ hash_bytes(&self, sizeof self, 0));
}
}
@@ -59,7 +65,7 @@ void
random_set_seed(uint32_t seed_)
{
ovs_assert(seed_);
seed = seed_;
*seed_get() = seed_;
}
void
@@ -120,9 +126,11 @@ random_range(int max)
static uint32_t
random_next(void)
{
seed ^= seed << 13;
seed ^= seed >> 17;
seed ^= seed << 5;
uint32_t *seedp = seed_get_unsafe();
return seed;
*seedp ^= *seedp << 13;
*seedp ^= *seedp >> 17;
*seedp ^= *seedp << 5;
return *seedp;
}