linux-kernel - Re: [PATCH 00/12] scsi/NCR5380: fix debugging macros and #include structure

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Date:	Tue, 18 Mar 2014 06:07:31 -0700
From:	Joe Perches <joe@...ches.com>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Finn Thain <fthain@...egraphics.com.au>,
	"James E.J. Bottomley" <JBottomley@...allels.com>,
	scsi <linux-scsi@...r.kernel.org>, Sam Creasey <sammy@...my.net>,
	Russell King <linux@....linux.org.uk>,
	Michael Schmitz <schmitz@...ian.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Linux/m68k <linux-m68k@...r.kernel.org>
Subject: Re: [PATCH 00/12] scsi/NCR5380: fix debugging macros and #include
 structure

On Tue, 2014-03-18 at 13:55 +0100, Geert Uytterhoeven wrote:
> On Tue, Mar 18, 2014 at 1:45 PM, Joe Perches <joe@...ches.com> wrote:

Hi Geert.

> > #define dprintk(flg, fmt, ...) \
> > do { if (0) pr_debug(fmt, ##__VA_ARGS__); } while (0)
> 
> Na, no_printk():
> 
> #define dprintk(flg, fmt, ...) no_printk(fmt, ##__VA_ARGS__)

Fine, but with a correction.

no_printk keeps all side effects like
performing any function calls made by the
statement or accessing any volatiles.

Using

do { if (0) no_printk(fmt, ##__VA_ARGS__); } while (0)

does not have any side-effects.


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