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Date: Wed, 13 Feb 2008 15:57:01 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Tejun Heo <htejun@gmail.com>
Cc: jeff@garzik.org, linux-ide@vger.kernel.org, jengelh@computergmbh.de,
       matthew@wil.cx, randy.dunlap@oracle.com, daniel.ritz-ml@swissonline.ch,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCHSET] printk: implement printk_header() and merging
 printk, take #3
Message-Id: <20080213155701.48871761.akpm@linux-foundation.org>
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On Wed, 13 Feb 2008 18:09:28 +0900
Tejun Heo <htejun@gmail.com> wrote:

> This is the third take of implement-printk_header-and-mprintk
> patchset.
> 
> Changes from the last take[L] are...
> 
> * Now header is printed on every line of a multiline message.  If the
>   header ends with ':' followed by spaces.  The colon is replaced with
>   space from the second line.
> 
> * s/mprintk/mprintk_flush/ and s/mprintk_add/mprintk/ as suggested.
> 
> * mprintk_init_alloc() and mprintk_free() added to ease malloc'd
>   buffer handling.  No need to specify buffer size.  Sizing is left to
>   mprintk.
> 
> This patchset aims to make printing multiline messages and assembling
> message piece-by-piece easier.
> 
> In a nutshell, printk_header() lets you do the following atomically
> (against other messages).
> 
>  code:
>   printk(KERN_INFO "ata1.00: ", "line0\nline1\nline2\n");
> 
>  output:
>   <6>ata1.00: line0
>   <6>ata1.00  line1
>   <6>ata1.00  line2

That seems sensible.

> And mprintk the following.
> 
>  code:
>   DEFINE_MPRINTK(mp, 2 * 80);
> 
>   mprintk_set_header(&mp, KERN_INFO "ata%u.%2u: ", 1, 0);
>   mprintk_push(&mp, "ATA %d", 7);
>   mprintk_push(&mp, ", %u sectors\n", 1024);
>   mprintk(&mp, "everything seems dandy\n");
> 
>  output:
>   <6>ata1.00: ATA 7, 1024 sectors
>   <6>ata1.00  everything seems dandy
> 

And that looks like an awful lot of fuss.  Is it really worth doing?