linux-kernel - Re: [PATCH -v2 1/2] ratelimit: Extend to print suppressed messages on release

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Date:	Fri, 1 Jul 2016 10:22:47 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>, Franck Bui <fbui@...e.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -v2 1/2] ratelimit: Extend to print suppressed messages
 on release


* Borislav Petkov <bp@...en8.de> wrote:

> +/* issue num suppressed message on exit */
> +#define RATELIMIT_MSG_ON_RELEASE	BIT(0)

So this flag says that we should issue a ratelimit message when it occurs.

> +static inline void ratelimit_state_exit(struct ratelimit_state *rs)
> +{
> +	if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE))
> +		return;
> +
> +	if (rs->missed)
> +		printk(KERN_WARNING "%s: %d callbacks suppressed\n",
> +		       current->comm, rs->missed);

... here we print the message if the RATELIMIT_MSG_ON_RELEASE bit is set.

> +++ b/lib/ratelimit.c
> @@ -46,12 +46,14 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
>  		rs->begin = jiffies;
>  
>  	if (time_is_before_jiffies(rs->begin + rs->interval)) {
> -		if (rs->missed)
> +		if (rs->missed && !(rs->flags & RATELIMIT_MSG_ON_RELEASE))
>  			printk(KERN_WARNING "%s: %d callbacks suppressed\n",
>  				func, rs->missed);

But here we print the message if the RATELIMIT_MSG_ON_RELEASE bit is zero.
Is that intentional?

Also, while we are changing it, I'd like to suggest a different message - it's 
talking about 'callbacks' but there's no callback here - we are skipping kernel 
log messages. So how about:

	pr_warn("%s: %d kernel log lines skipped, due to rate-limiting.\n"

Thanks,

	Ingo