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/*
* ratelimit.c - Do something with rate limit.
*
* Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
*
* This file is released under the GPLv2.
*
*/
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/module.h>
/*
* __ratelimit - rate limiting
* @ratelimit_jiffies: minimum time in jiffies between two callbacks
* @ratelimit_burst: number of callbacks we do before ratelimiting
*
* This enforces a rate limit: not more than @ratelimit_burst callbacks
* in every ratelimit_jiffies
*/
int __ratelimit(int ratelimit_jiffies, int ratelimit_burst)
{
static DEFINE_SPINLOCK(ratelimit_lock);
static unsigned 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 "%s: %d messages suppressed\n",
__func__, lost);
return 1;
}
missed++;
spin_unlock_irqrestore(&ratelimit_lock, flags);
return 0;
}
EXPORT_SYMBOL(__ratelimit);
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