linux-kernel - Re: [PATCH] show message when exceeded rlimit of pending signals

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Message-ID: <1256939158.1917.43.camel@Joe-Laptop.home>
Date:	Fri, 30 Oct 2009 14:45:58 -0700
From:	Joe Perches <joe@...ches.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Naohiro Ooiwa <nooiwa@...aclelinux.com>,
	Ingo Molnar <mingo@...e.hu>,
	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>,
	roland@...hat.com, Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>, oleg@...hat.com
Subject: Re: [PATCH] show message when exceeded rlimit of pending signals

On Fri, 2009-10-30 at 14:33 -0700, Andrew Morton wrote:
> On Fri, 30 Oct 2009 20:36:31 +0900
> Naohiro Ooiwa <nooiwa@...aclelinux.com> wrote:
> > +static void show_reach_rlimit_sigpending(void)
> > +	if (!printk_ratelimit())
> > +		return;
> 
> printk_ratelimit() is a bad thing and we should be working toward
> removing it altogether, not adding new callers.
> 
> Because it uses global state.  So if subsystem A is trying to generate
> lots of printk's, subsystem B's important message might get
> accidentally suppressed.

http://lkml.org/lkml/2009/9/21/323

I think there should be a generic kernel.h macro for this.
Something like:

#define printk_ratelimited(fmt, arg...)			\
({	static struct ratelimit_state _rs = {		\
		.interval = DEFAULT_RATELIMIT_INTERVAL,	\
		.burst = DEFAULT_RATELIMIT_BURST,	\
	};						\
	int rtn;					\
							\
	if (!__ratelimit(&_rs))				\
		rtn = printk(fmt, ##arg);		\
	else						\
		rtn = 0;				\
	rtn;						\
})
#define pr_info_rl(fmt, arg) \
	printk_ratelimited(KERN_INFO pr_fmt(fmt), ##arg)
etc...



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