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Remove unnecessary spinlocks from random_jkiss

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Removing the locks will increase the randomness of the random number
generation by introducing race conditions into the code.
This commit is contained in:
Markus Mäkelä 2017-02-08 14:18:56 +02:00
parent a6698c6f07
commit 517ecd9a12
1 changed files with 0 additions and 9 deletions
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9
server/core/random_jkiss.c
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@ -31,7 +31,6 @@
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <maxscale/spinlock.h>
#include <maxscale/random_jkiss.h>
/* Public domain code for JKISS RNG - Comment header added */
@ -42,8 +41,6 @@
static unsigned int x = 123456789, y = 987654321, z = 43219876, c = 6543217; /* Seed variables */
static bool init = false;
static SPINLOCK random_jkiss_spinlock = SPINLOCK_INIT;
static unsigned int random_jkiss_devrand(void);
static void random_init_jkiss(void);
@ -60,14 +57,11 @@ random_jkiss(void)
unsigned long long t;
unsigned int result;
spinlock_acquire(&random_jkiss_spinlock);
if (!init)
{
/* Must set init first because initialisation calls this function */
init = true;
spinlock_release(&random_jkiss_spinlock);
random_init_jkiss();
spinlock_acquire(&random_jkiss_spinlock);
}
x = 314527869 * x + 1234567;
y ^= y << 5;
@ -77,7 +71,6 @@ random_jkiss(void)
c = t >> 32;
z = t;
result = x + y + z;
spinlock_release(&random_jkiss_spinlock);
return result;
}
@ -120,7 +113,6 @@ random_init_jkiss(void)
{
int newrand, i;
spinlock_acquire(&random_jkiss_spinlock);
if ((newrand = random_jkiss_devrand()) != 0)
{
x = newrand;
@ -140,7 +132,6 @@ random_init_jkiss(void)
{
c = newrand % 698769068 + 1; /* Should be less than 698769069 */
}
spinlock_release(&random_jkiss_spinlock);
/* "Warm up" our random number generator */
for (i = 0; i < 100; i++)