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/*
* ratelimit.c - Do something with rate limit.
*
* Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
*
* 2008-05-01 rewrite the function and use a ratelimit_state data struct as
* parameter. Now every user can use their own standalone ratelimit_state.
*
* This file is released under the GPLv2.
*/
#include <linux/ratelimit.h>
#include <linux/jiffies.h>
#include <linux/module.h>
/*
* __ratelimit - rate limiting
* @rs: ratelimit_state data
*
* This enforces a rate limit: not more than @rs->ratelimit_burst callbacks
* in every @rs->ratelimit_jiffies
*/
int __ratelimit(struct ratelimit_state *rs)
{
unsigned long flags;
int ret;
if (!rs->interval)
return 1;
/*
* If we contend on this state's lock then almost
* by definition we are too busy to print a message,
* in addition to the one that will be printed by
* the entity that is holding the lock already:
*/
if (!spin_trylock_irqsave(&rs->lock, flags))
return 1;
if (!rs->begin)
rs->begin = jiffies;
if (time_is_before_jiffies(rs->begin + rs->interval)) {
if (rs->missed)
printk(KERN_WARNING "%s: %d callbacks suppressed\n",
__func__, rs->missed);
rs->begin = 0;
rs->printed = 0;
rs->missed = 0;
}
if (rs->burst && rs->burst > rs->printed) {
rs->printed++;
ret = 1;
} else {
rs->missed++;
ret = 0;
}
spin_unlock_irqrestore(&rs->lock, flags);
return ret;
}
EXPORT_SYMBOL(__ratelimit);
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