[mirror_ubuntu-artful-kernel.git] / lib / ratelimit.c

/*
 * 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) {
			if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
				pr_warn("%s: %d callbacks suppressed\n", func, rs->missed);
				rs->missed = 0;
			}
		}
		rs->begin   = jiffies;
		rs->printed = 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);
Commit	Line	Data
5f97a5a8 DY	1	/*
	2	* ratelimit.c - Do something with rate limit.
	3	*
	4	* Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
	5	*
717115e1 DY	6	* 2008-05-01 rewrite the function and use a ratelimit_state data struct as
	7	* parameter. Now every user can use their own standalone ratelimit_state.
	8	*
5f97a5a8	9	* This file is released under the GPLv2.
5f97a5a8 DY	10	*/
5f97a5a8 DY	11
3fff4c42	12	#include <linux/ratelimit.h>
5f97a5a8	13	#include <linux/jiffies.h>
8bc3bcc9	14	#include <linux/export.h>
5f97a5a8 DY	15
	16	/*
	17	* __ratelimit - rate limiting
717115e1	18	* @rs: ratelimit_state data
2a7268ab	19	* @func: name of calling function
5f97a5a8	20	*
2a7268ab YZ	21	* This enforces a rate limit: not more than @rs->burst callbacks
	22	* in every @rs->interval
	23	*
	24	* RETURNS:
	25	* 0 means callbacks will be suppressed.
	26	* 1 means go ahead and do it.
5f97a5a8	27	*/
5c828713	28	int ___ratelimit(struct ratelimit_state rs, const char func)
5f97a5a8	29	{
4d9c377c	30	unsigned long flags;
979f693d	31	int ret;
4d9c377c	32
717115e1 DY	33	if (!rs->interval)
717115e1 DY	34	return 1;
5f97a5a8	35
edaac8e3 IM	36	/*
	37	* If we contend on this state's lock then almost
	38	* by definition we are too busy to print a message,
	39	* in addition to the one that will be printed by
	40	* the entity that is holding the lock already:
	41	*/
07354eb1	42	if (!raw_spin_trylock_irqsave(&rs->lock, flags))
57119c34	43	return 0;
edaac8e3	44
717115e1 DY	45	if (!rs->begin)
717115e1 DY	46	rs->begin = jiffies;
5f97a5a8	47
717115e1	48	if (time_is_before_jiffies(rs->begin + rs->interval)) {
6b1d174b BP	49	if (rs->missed) {
	50	if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
	51	pr_warn("%s: %d callbacks suppressed\n", func, rs->missed);
	52	rs->missed = 0;
	53	}
	54	}
c2594bc3	55	rs->begin = jiffies;
717115e1	56	rs->printed = 0;
5f97a5a8	57	}
979f693d IM	58	if (rs->burst && rs->burst > rs->printed) {
	59	rs->printed++;
	60	ret = 1;
	61	} else {
	62	rs->missed++;
	63	ret = 0;
	64	}
07354eb1	65	raw_spin_unlock_irqrestore(&rs->lock, flags);
717115e1	66
979f693d	67	return ret;
5f97a5a8	68	}
5c828713	69	EXPORT_SYMBOL(___ratelimit);