52 lines
1.3 KiB
C
52 lines
1.3 KiB
C
/*
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* ratelimit.c - Do something with rate limit.
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*
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* Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
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*
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* This file is released under the GPLv2.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/jiffies.h>
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#include <linux/module.h>
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/*
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* __ratelimit - rate limiting
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* @ratelimit_jiffies: minimum time in jiffies between two callbacks
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* @ratelimit_burst: number of callbacks we do before ratelimiting
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*
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* This enforces a rate limit: not more than @ratelimit_burst callbacks
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* in every ratelimit_jiffies
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*/
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int __ratelimit(int ratelimit_jiffies, int ratelimit_burst)
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{
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static DEFINE_SPINLOCK(ratelimit_lock);
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static unsigned toks = 10 * 5 * HZ;
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static unsigned long last_msg;
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static int missed;
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unsigned long flags;
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unsigned long now = jiffies;
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spin_lock_irqsave(&ratelimit_lock, flags);
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toks += now - last_msg;
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last_msg = now;
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if (toks > (ratelimit_burst * ratelimit_jiffies))
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toks = ratelimit_burst * ratelimit_jiffies;
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if (toks >= ratelimit_jiffies) {
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int lost = missed;
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missed = 0;
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toks -= ratelimit_jiffies;
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spin_unlock_irqrestore(&ratelimit_lock, flags);
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if (lost)
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printk(KERN_WARNING "%s: %d messages suppressed\n",
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__func__, lost);
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return 1;
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}
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missed++;
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spin_unlock_irqrestore(&ratelimit_lock, flags);
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return 0;
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}
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EXPORT_SYMBOL(__ratelimit);
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