| Dave Young | 5f97a5a | 2008-04-29 00:59:43 -0700 | [diff] [blame] | 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 | * This file is released under the GPLv2. |
| 7 | * |
| 8 | */ |
| 9 | |
| 10 | #include <linux/kernel.h> |
| 11 | #include <linux/jiffies.h> |
| 12 | #include <linux/module.h> |
| 13 | |
| 14 | /* |
| 15 | * __ratelimit - rate limiting |
| 16 | * @ratelimit_jiffies: minimum time in jiffies between two callbacks |
| 17 | * @ratelimit_burst: number of callbacks we do before ratelimiting |
| 18 | * |
| 19 | * This enforces a rate limit: not more than @ratelimit_burst callbacks |
| 20 | * in every ratelimit_jiffies |
| 21 | */ |
| 22 | int __ratelimit(int ratelimit_jiffies, int ratelimit_burst) |
| 23 | { |
| 24 | static DEFINE_SPINLOCK(ratelimit_lock); |
| 25 | static unsigned toks = 10 * 5 * HZ; |
| 26 | static unsigned long last_msg; |
| 27 | static int missed; |
| 28 | unsigned long flags; |
| 29 | unsigned long now = jiffies; |
| 30 | |
| 31 | spin_lock_irqsave(&ratelimit_lock, flags); |
| 32 | toks += now - last_msg; |
| 33 | last_msg = now; |
| 34 | if (toks > (ratelimit_burst * ratelimit_jiffies)) |
| 35 | toks = ratelimit_burst * ratelimit_jiffies; |
| 36 | if (toks >= ratelimit_jiffies) { |
| 37 | int lost = missed; |
| 38 | |
| 39 | missed = 0; |
| 40 | toks -= ratelimit_jiffies; |
| 41 | spin_unlock_irqrestore(&ratelimit_lock, flags); |
| 42 | if (lost) |
| 43 | printk(KERN_WARNING "%s: %d messages suppressed\n", |
| 44 | __func__, lost); |
| 45 | return 1; |
| 46 | } |
| 47 | missed++; |
| 48 | spin_unlock_irqrestore(&ratelimit_lock, flags); |
| 49 | return 0; |
| 50 | } |
| 51 | EXPORT_SYMBOL(__ratelimit); |