/*
   * 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/kernel.h>
  #include <linux/jiffies.h>
  #include <linux/module.h>

  static DEFINE_SPINLOCK(ratelimit_lock);

  /*
   * __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;

  	if (!rs->interval)
  		return 1;

  
  	spin_lock_irqsave(&ratelimit_lock, flags);

  	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
  ",
  				__func__, rs->missed);
  		rs->begin = 0;
  		rs->printed = 0;
  		rs->missed = 0;

  	}

  	if (rs->burst && rs->burst > rs->printed)
  		goto print;
  
  	rs->missed++;

  	spin_unlock_irqrestore(&ratelimit_lock, flags);
  	return 0;

  
  print:
  	rs->printed++;
  	spin_unlock_irqrestore(&ratelimit_lock, flags);
  	return 1;

  }
  EXPORT_SYMBOL(__ratelimit);