linux-kernel - Re: [23/27] kernel.h: add printk_ratelimited and pr_<level>

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Message-ID: <20120124144613.GD3180@pcarmody2.research.nokia.com>
Date:	Tue, 24 Jan 2012 16:46:13 +0200
From:	Phil Carmody <ext-phil.2.carmody@...ia.com>
To:	ext Greg KH <gregkh@...e.de>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Paolo Bonzini <pbonzini@...hat.com>,
	Petr Matousek <pmatouse@...hat.com>,
	linux-scsi@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
	James Bottomley <JBottomley@...allels>
Subject: Re: [23/27] kernel.h: add printk_ratelimited and pr_<level>_rl

On 23/01/12 15:41 -0800, ext Greg KH wrote:
> 2.6.32-longterm review patch.  If anyone has any objections, please let me know.

This looks like an added feature with no users in .32 - does it really 
belong in a stable tree?
(But to be explicit, I have no issue with its contents at all.)

Phil

> ------------------
> 
> 
> From: Joe Perches <joe@...ches.com>
> 
> commit 8a64f336bc1d4aa203b138d29d5a9c414a9fbb47 upstream.
> 
> 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.
> 
> [akpm@...ux-foundation.org: coding-style fixes]
> [akpm@...ux-foundation.org: s/_rl/_ratelimited/g]
> Signed-off-by: Joe Perches <joe@...ches.com>
> Cc: Naohiro Ooiwa <nooiwa@...aclelinux.com>
> Cc: Ingo Molnar <mingo@...e.hu>
> Cc: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> 
> ---
>  include/linux/kernel.h |   44 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
> 
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -407,6 +407,50 @@ static inline char *pack_hex_byte(char *
>  #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_ratelimited(fmt, ...) \
> +	printk_ratelimited(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
> +#define pr_alert_ratelimited(fmt, ...) \
> +	printk_ratelimited(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__)
> +#define pr_crit_ratelimited(fmt, ...) \
> +	printk_ratelimited(KERN_CRIT pr_fmt(fmt), ##__VA_ARGS__)
> +#define pr_err_ratelimited(fmt, ...) \
> +	printk_ratelimited(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
> +#define pr_warning_ratelimited(fmt, ...) \
> +	printk_ratelimited(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
> +#define pr_notice_ratelimited(fmt, ...) \
> +	printk_ratelimited(KERN_NOTICE pr_fmt(fmt), ##__VA_ARGS__)
> +#define pr_info_ratelimited(fmt, ...) \
> +	printk_ratelimited(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
> +/* no pr_cont_ratelimited, don't do that... */
> +/* If you are writing a driver, please use dev_dbg instead */
> +#if defined(DEBUG)
> +#define pr_debug_ratelimited(fmt, ...) \
> +	printk_ratelimited(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
> +#else
> +#define pr_debug_ratelimited(fmt, ...) \
> +	({ if (0) printk_ratelimited(KERN_DEBUG pr_fmt(fmt), \
> +				     ##__VA_ARGS__); 0; })
> +#endif
> +
> +/*
>   * General tracing related utility functions - trace_printk(),
>   * tracing_on/tracing_off and tracing_start()/tracing_stop
>   *
> 
> 
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