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/*
* Copyright 2005 (C) Michael Richardson <mcr@xelerance.com>
*
* This is a file of functions which are present in 2.6 kernels,
* but are not available by default in the 2.4 series.
*
* As such this code is usually from the Linux kernel, and is covered by
* GPL.
*
* 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. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* $Id: ipsec_kern24.c,v 1.2 2005/05/20 03:19:18 mcr Exp $
*
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
/*
* printk rate limiting, lifted from the networking subsystem.
*
* This enforces a rate limit: not more than one kernel message
* every printk_ratelimit_jiffies to make a denial-of-service
* attack impossible.
*/
static spinlock_t ratelimit_lock = SPIN_LOCK_UNLOCKED;
int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst)
{
static unsigned long toks = 10*5*HZ;
static unsigned long last_msg;
static int missed;
unsigned long flags;
unsigned long now = jiffies;
spin_lock_irqsave(&ratelimit_lock, flags);
toks += now - last_msg;
last_msg = now;
if (toks > (ratelimit_burst * ratelimit_jiffies))
toks = ratelimit_burst * ratelimit_jiffies;
if (toks >= ratelimit_jiffies) {
int lost = missed;
missed = 0;
toks -= ratelimit_jiffies;
spin_unlock_irqrestore(&ratelimit_lock, flags);
if (lost)
printk(KERN_WARNING "printk: %d messages suppressed.\n", lost);
return 1;
}
missed++;
spin_unlock_irqrestore(&ratelimit_lock, flags);
return 0;
}
/* minimum time in jiffies between messages */
int printk_ratelimit_jiffies = 5*HZ;
/* number of messages we send before ratelimiting */
int printk_ratelimit_burst = 10;
int printk_ratelimit(void)
{
return __printk_ratelimit(printk_ratelimit_jiffies,
printk_ratelimit_burst);
}
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