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SubjectRe: [PATCH RFC] [1/3] isolate ratelimit from printk.c for other use
On Mon, 10 Mar 2008 14:31:15 +0800 Dave Young wrote:

> This series include 3 patch, they need to be applied in order.
> 1) isolate ratelimit from printk.c
> 2) add WARN_ON_SECS macro
> 3) use WARN_ON_SECS macro in rcupreempt.h
>
> Please give some comments and suggestions for improvement, thanks.
>
> ---
>
> Due to the rcupreempt.h WARN_ON trigged, I got 2G syslog file. For some
> serious complaining of kernel, we need repeat the warnings, so here I
> isolate the ratelimit part of printk.c to a standalone file.
>
> Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
>
> ---
> include/linux/kernel.h | 1
> kernel/printk.c | 26 ------------------------
> lib/Makefile | 2 -
> lib/ratelimit.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 54 insertions(+), 26 deletions(-)

> diff -uprN linux/lib/ratelimit.c linux.new/lib/ratelimit.c
> --- linux/lib/ratelimit.c 1970-01-01 07:00:00.000000000 +0700
> +++ linux.new/lib/ratelimit.c 2008-03-10 13:42:46.000000000 +0800
> @@ -0,0 +1,51 @@
> +/*
> + * 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 too callbacks

s/too/two/

> + * @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 "__ratelimit: %d messages"
> + " suppressed.\n", lost);

Would be better not to split the string, e.g.:

printk(KERN_WARNING "%s: %d messages suppressed\n",
__func__, lost);

> + return 1;
> + }
> + missed++;
> + spin_unlock_irqrestore(&ratelimit_lock, flags);
> + return 0;
> +}
> +EXPORT_SYMBOL(__ratelimit);

---
~Randy


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