linux-kernel - Re: [PATCH] kernel.h: Add printk_ratelimited and pr_<level>

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Message-ID: <4AF2E4B1.7030202@miraclelinux.com>
Date:	Thu, 05 Nov 2009 23:44:01 +0900
From:	Naohiro Ooiwa <nooiwa@...aclelinux.com>
To:	Ingo Molnar <mingo@...e.hu>, Joe Perches <joe@...ches.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	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,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] kernel.h: Add printk_ratelimited and pr_<level>_rl

Naohiro Ooiwa wrote:
> Ingo Molnar wrote:
>> * Joe Perches <joe@...ches.com> wrote:
>>
>>> Add a printk_ratelimited statement expression macro that uses a 
>>> per-call ratelimit_state so that multiple subsystems output messages 
>>> are not suppressed by a global __ratelimit state.
>>>
>>> Signed-off-by: Joe Perches <joe@...ches.com>
>>>
>>> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
>>> index f4e3184..555560c 100644
>>> --- a/include/linux/kernel.h
>>> +++ b/include/linux/kernel.h
>>> @@ -407,6 +407,50 @@ static inline char *pack_hex_byte(char *buf, u8 byte)
>>>  #endif
>>>  
>>>  /*
>>> + * ratelimited messages with local ratelimit_state,
>>> + * no local ratelimit_state used in the !PRINTK case
>>> + */
>>> +#ifdef CONFIG_PRINTK
>>> +#define printk_ratelimited(fmt, ...)  ({		\
>>> +	static struct ratelimit_state _rs = {		\
>>> +		.interval = DEFAULT_RATELIMIT_INTERVAL, \
>>> +		.burst = DEFAULT_RATELIMIT_BURST,       \
>>> +	};                                              \
>>> +							\
>>> +	if (!__ratelimit(&_rs))                         \
>>> +		printk(fmt, ##__VA_ARGS__);		\
>>> +})
>>> +#else
>>> +/* No effect, but we still get type checking even in the !PRINTK case: */
>>> +#define printk_ratelimited printk
>>> +#endif
>>> +
>>> +#define pr_emerg_rl(fmt, ...) \
>>> +        printk_ratelimited(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
>>> +#define pr_alert_rl(fmt, ...) \
>>> +        printk_ratelimited(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__)
>>> +#define pr_crit_rl(fmt, ...) \
>>> +        printk_ratelimited(KERN_CRIT pr_fmt(fmt), ##__VA_ARGS__)
>>> +#define pr_err_rl(fmt, ...) \
>>> +        printk_ratelimited(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
>>> +#define pr_warning_rl(fmt, ...) \
>>> +        printk_ratelimited(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
>>> +#define pr_notice_rl(fmt, ...) \
>>> +        printk_ratelimited(KERN_NOTICE pr_fmt(fmt), ##__VA_ARGS__)
>>> +#define pr_info_rl(fmt, ...) \
>>> +        printk_ratelimited(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
>>> +/* no pr_cont_rl, don't do that... */
>>> +/* If you are writing a driver, please use dev_dbg instead */
>>> +#if defined(DEBUG)
>>> +#define pr_debug_rl(fmt, ...) \
>>> +	printk_ratelimited(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
>>> +#else
>>> +#define pr_debug_rl(fmt, ...) \
>>> +	({ if (0) printk_ratelimited(KERN_DEBUG pr_fmt(fmt), \
>>> +				     ##__VA_ARGS__); 0; })
>>> +#endif
>>> +
>> Looks like a useful addition. Somewhat bloatier, but then again, more 
>> correct and the bloat problem can be solved by explicit state 
>> definitions.
>>
>> 	Ingo
> 
> I waiting for this patch to merge.
> And then, I think I will remake my patch.
> 
> How do you delete printk_ratelimit() in this patch at a same time ?
> 
> I have a personal question.
> Why aren't they codes in the include/linux/ratelimit.h ?
> 

Ah, They are originally in kernel.h . Sorry.

> 
> Thanks.
> Naohiro Ooiwa
> 
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