linux-kernel - Re: do { } while (0) question

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Date:	Tue, 01 Aug 2006 10:51:38 +0159
From:	Jiri Slaby <jirislaby@...il.com>
To:	Heiko Carstens <heiko.carstens@...ibm.com>
CC:	Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org,
	Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: Re: do { } while (0) question

Heiko Carstens wrote:
> Hi Andrew,
> 
> your commit e2c2770096b686b4d2456173f53cb50e01aa635c does this:
> 
> ---
> Always use do {} while (0).  Failing to do so can cause subtle compile
> failures or bugs.
> 
> -#define hotcpu_notifier(fn, pri)
> -#define register_hotcpu_notifier(nb)
> -#define unregister_hotcpu_notifier(nb)
> +#define hotcpu_notifier(fn, pri)	do { } while (0)
> +#define register_hotcpu_notifier(nb)	do { } while (0)
> +#define unregister_hotcpu_notifier(nb)	do { } while (0)

#if KILLER == 1
#define MACRO
#else
#define MACRO do { } while (0)
#endif

{
	if (some_condition)
		MACRO

	if_this_is_not_called_you_loose_your_data();
}

How do you want to define KILLER, 0 or 1? I personally choose 0.

regards,
-- 
<a href="http://www.fi.muni.cz/~xslaby/">Jiri Slaby</a>
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8  22A0 32CC 55C3 39D4 7A7E
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