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