linux-kernel - Re: [PATCH] thinkpad_acpi: Remove side effects from vdbg_printk -> no

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Message-ID: <20150827173306.GB17280@khazad-dum.debian.net>
Date:	Thu, 27 Aug 2015 14:33:06 -0300
From:	Henrique de Moraes Holschuh <hmh@....eng.br>
To:	Joe Perches <joe@...ches.com>
Cc:	Darren Hart <dvhart@...radead.org>,
	ibm-acpi-devel@...ts.sourceforge.net,
	platform-driver-x86@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] thinkpad_acpi: Remove side effects from vdbg_printk ->
 no_printk macro

On Wed, 26 Aug 2015, Joe Perches wrote:
> vdbg_printk when not using CONFIG_THINKPAD_ACPI_DEBUG uses
> no_printk which produces no logging output but always
> evaluates arguments.
> 
> Change the macro to surround the no_printk call with
> 	do { if (0) no_printk(...); } while (0)
> to avoid the unnecessary argument evaluations.
> 
> $ size drivers/platform/x86/thinkpad_acpi.o*
>    text	   data	    bss	    dec	    hex	filename
>   60918	   6184	    824	  67926	  10956	drivers/platform/x86/thinkpad_acpi.o.new
>   60927	   6184	    824	  67935	  1095f	drivers/platform/x86/thinkpad_acpi.o.old
> 
> Signed-off-by: Joe Perches <joe@...ches.com>

Acked-by: Henrique de Moraes Holschuh <hmh@....eng.br>

> ---
>  drivers/platform/x86/thinkpad_acpi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
> index 33e488c..131dd74 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -402,7 +402,7 @@ static const char *str_supported(int is_supported);
>  #else
>  static inline const char *str_supported(int is_supported) { return ""; }
>  #define vdbg_printk(a_dbg_level, format, arg...)	\
> -	no_printk(format, ##arg)
> +	do { if (0) no_printk(format, ##arg); } while (0)
>  #endif
>  
>  static void tpacpi_log_usertask(const char * const what)
> 

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh
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