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Cc: Vegard Nossum <vegard.nossum@gmail.com>,
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From: Kyle Moffett <mrmacman_g4@mac.com>
Subject: Re: [RFC] New kernel-message logging API (take 2)
Date: Fri, 28 Sep 2007 03:44:24 -0400
To: Geert Uytterhoeven <geert@linux-m68k.org>
Sender: linux-kernel-owner@vger.kernel.org
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On Sep 28, 2007, at 03:31:11, Geert Uytterhoeven wrote:
> Can't you store the loglevel in the kprint_block and check it in  
> all successive kprint_*() macros? If gcc knows it's constant, it  
> can optimize the non-wanted code away. As other fields in struct  
> kprint_block cannot be constant (they store internal state), you  
> have to split it like:
>
>     struct kprint_block {
> 	    int loglevel;
> 	    struct real_kprint_block real;  /* internal state */
>     }
>
> and pass &block.real() instead of &block to all successive internal  
> functions.  I haven't tried this, so let's hope gcc is actually  
> smart enough...

Well actually, I believe you could just do:

struct kprint_block {
	const int loglevel;
	[...];
};

Then cast away the constness to actually set it initially:
*((int *)&block.loglevel) = LOGLEVEL;

Cheers,
Kyle Moffett

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