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tag: v3.5-rc4
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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/export.h>

/*
* __ratelimit - rate limiting
* @rs: ratelimit_state data
* @func: name of calling function
*
* This enforces a rate limit: not more than @rs->burst callbacks
* in every @rs->interval
*
* RETURNS:
* 0 means callbacks will be suppressed.
* 1 means go ahead and do it.
*/
int ___ratelimit(struct ratelimit_state *rs, const char *func)
{
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 (!raw_spin_trylock_irqsave(&rs->lock, flags))
return 0;

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;
}
raw_spin_unlock_irqrestore(&rs->lock, flags);

return ret;
}
EXPORT_SYMBOL(___ratelimit);
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