linux-kernel - Re: [RFC] New kernel-message logging API (take 2)

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Message-ID: <122e.46fcb9d3.ac322@altium.nl>
Date:	Fri, 28 Sep 2007 08:22:43 -0000
From:	dick.streefland@...ium.nl (Dick Streefland)
To:	linux-kernel@...r.kernel.org
Subject: Re: [RFC] New kernel-message logging API (take 2)

"Vegard Nossum" <vegard.nossum@...il.com> wrote:
|   It should be possible to optimize out multi-line (block) entries
| based on log-level filtering even though the log-level is only given
| in the first call (the initializer). It may take the shape of an
| if-block that spans several macros. This is not very elegant or robust
| if the macros are used incorrectly, however. Aborting a message can
| also be hard this way (since the abort would usually appear inside an
| if-statement that tests for some abnormal condition, thus appear in a
| different block, and thoroughly mess up the bracket order).
| 
| Example: {
| 	#define kprint_block_init(block, loglevel)		\
| 		if(loglevel > CONFIG_KPRINT_LOGLEVEL_MAX) {	\
| 			kprint_real_block_init(block, loglevel);
| 
| 	#define kprint_block(block, fmt, ...)			\
| 		kprint_real_block(block, fmt, ## __VA_ARGS__);
| 
| 	#define kprint_block_flush(block)			\
| 			kprint_real_block_flush(block);		\
| 		}

As you point out yourself, this is not very elegant or robust. In fact,
it is very dangerous. Why not simply pass the loglevel to each macro?

-- 
Dick Streefland                      ////                      Altium BV
dick.streefland@...ium.nl           (@ @)          http://www.altium.com
--------------------------------oOO--(_)--OOo---------------------------

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