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

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Date:	Tue, 18 Mar 2014 14:13:53 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Joe Perches <joe@...ches.com>
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

Hi Joe,

On Tue, Mar 18, 2014 at 2:07 PM, Joe Perches <joe@...ches.com> wrote:
> 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:
>> > #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.

That's true...

> Using
>
> do { if (0) no_printk(fmt, ##__VA_ARGS__); } while (0)
>
> does not have any side-effects.

... but all current users in include/ have the side-effects.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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