linux/lib/ratelimit.c

5f97a5a8SDave Young/*
5f97a5a8SDave Young * ratelimit.c - Do something with rate limit.
5f97a5a8SDave Young *
5f97a5a8SDave Young * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
5f97a5a8SDave Young *
717115e1SDave Young * 2008-05-01 rewrite the function and use a ratelimit_state data struct as
717115e1SDave Young * parameter. Now every user can use their own standalone ratelimit_state.
717115e1SDave Young *
5f97a5a8SDave Young * This file is released under the GPLv2.
5f97a5a8SDave Young *
5f97a5a8SDave Young */
5f97a5a8SDave Young
5f97a5a8SDave Young#include <linux/kernel.h>
5f97a5a8SDave Young#include <linux/jiffies.h>
5f97a5a8SDave Young#include <linux/module.h>
5f97a5a8SDave Young
717115e1SDave Youngstatic DEFINE_SPINLOCK(ratelimit_lock);
717115e1SDave Young
5f97a5a8SDave Young/*
5f97a5a8SDave Young * __ratelimit - rate limiting
717115e1SDave Young * @rs: ratelimit_state data
5f97a5a8SDave Young *
717115e1SDave Young * This enforces a rate limit: not more than @rs->ratelimit_burst callbacks
717115e1SDave Young * in every @rs->ratelimit_jiffies
5f97a5a8SDave Young */
717115e1SDave Youngint __ratelimit(struct ratelimit_state *rs)
5f97a5a8SDave Young{
*4d9c377cSAlexey Dobriyan	unsigned long flags;
*4d9c377cSAlexey Dobriyan
717115e1SDave Young	if (!rs->interval)
717115e1SDave Young		return 1;
5f97a5a8SDave Young
5f97a5a8SDave Young	spin_lock_irqsave(&ratelimit_lock, flags);
717115e1SDave Young	if (!rs->begin)
717115e1SDave Young		rs->begin = jiffies;
5f97a5a8SDave Young
717115e1SDave Young	if (time_is_before_jiffies(rs->begin + rs->interval)) {
717115e1SDave Young		if (rs->missed)
717115e1SDave Young			printk(KERN_WARNING "%s: %d callbacks suppressed\n",
717115e1SDave Young				__func__, rs->missed);
717115e1SDave Young		rs->begin = 0;
717115e1SDave Young		rs->printed = 0;
717115e1SDave Young		rs->missed = 0;
5f97a5a8SDave Young	}
717115e1SDave Young	if (rs->burst && rs->burst > rs->printed)
717115e1SDave Young		goto print;
717115e1SDave Young
717115e1SDave Young	rs->missed++;
5f97a5a8SDave Young	spin_unlock_irqrestore(&ratelimit_lock, flags);
5f97a5a8SDave Young	return 0;
717115e1SDave Young
717115e1SDave Youngprint:
717115e1SDave Young	rs->printed++;
717115e1SDave Young	spin_unlock_irqrestore(&ratelimit_lock, flags);
717115e1SDave Young	return 1;
5f97a5a8SDave Young}
5f97a5a8SDave YoungEXPORT_SYMBOL(__ratelimit);