1/*
2 * ratelimit.c - Do something with rate limit.
3 *
4 * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
5 *
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 *
9 * This file is released under the GPLv2.
10 */
11
12#include <linux/ratelimit.h>
13#include <linux/jiffies.h>
14#include <linux/export.h>
15
16/*
17 * __ratelimit - rate limiting
18 * @rs: ratelimit_state data
19 * @func: name of calling function
20 *
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.
27 */
28int ___ratelimit(struct ratelimit_state *rs, const char *func)
29{
30 unsigned long flags;
31 int ret;
32
33 if (!rs->interval)
34 return 1;
35
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 */
42 if (!raw_spin_trylock_irqsave(&rs->lock, flags))
43 return 0;
44
45 if (!rs->begin)
46 rs->begin = jiffies;
47
48 if (time_is_before_jiffies(rs->begin + rs->interval)) {
49 if (rs->missed) {
50 if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
51 printk_deferred(KERN_WARNING
52 "%s: %d callbacks suppressed\n",
53 func, rs->missed);
54 rs->missed = 0;
55 }
56 }
57 rs->begin = jiffies;
58 rs->printed = 0;
59 }
60 if (rs->burst && rs->burst > rs->printed) {
61 rs->printed++;
62 ret = 1;
63 } else {
64 rs->missed++;
65 ret = 0;
66 }
67 raw_spin_unlock_irqrestore(&rs->lock, flags);
68
69 return ret;
70}
71EXPORT_SYMBOL(___ratelimit);
72