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
13 #include <linux/kernel.h>
14 #include <linux/jiffies.h>
15 #include <linux/module.h>
16
17 static DEFINE_SPINLOCK(ratelimit_lock);
18
19 /*
20 * __ratelimit - rate limiting
21 * @rs: ratelimit_state data
22 *
23 * This enforces a rate limit: not more than @rs->ratelimit_burst callbacks
24 * in every @rs->ratelimit_jiffies
25 */
26 int __ratelimit(struct ratelimit_state *rs)
27 {
28 unsigned long flags;
29
30 if (!rs->interval)
31 return 1;
32
33 spin_lock_irqsave(&ratelimit_lock, flags);
34 if (!rs->begin)
35 rs->begin = jiffies;
36
37 if (time_is_before_jiffies(rs->begin + rs->interval)) {
38 if (rs->missed)
39 printk(KERN_WARNING "%s: %d callbacks suppressed\n",
40 __func__, rs->missed);
41 rs->begin = 0;
42 rs->printed = 0;
43 rs->missed = 0;
44 }
45 if (rs->burst && rs->burst > rs->printed)
46 goto print;
47
48 rs->missed++;
49 spin_unlock_irqrestore(&ratelimit_lock, flags);
50 return 0;
51
52 print:
53 rs->printed++;
54 spin_unlock_irqrestore(&ratelimit_lock, flags);
55 return 1;
56 }
57 EXPORT_SYMBOL(__ratelimit);
58
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