linux-kernel - Re: [PATCH] Prefix each line of multiline printk(KERN_<level> "foo\nbar") with KERN

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Message-ID: <Pine.LNX.4.64N.0708291205020.26167@blysk.ds.pg.gda.pl>
Date:	Wed, 29 Aug 2007 12:22:41 +0100 (BST)
From:	"Maciej W. Rozycki" <macro@...ux-mips.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
cc:	Mike Frysinger <vapier.adi@...il.com>,
	Joe Perches <joe@...ches.com>, linux-kernel@...r.kernel.org,
	blinux-list@...hat.com, cluster-devel@...hat.com,
	discuss@...-64.org, jffs-dev@...s.com, linux-acpi@...r.kernel.org,
	linux-ide@...r.kernel.org, linux-mips@...ux-mips.org,
	linux-mm@...ck.org, linux-mtd@...ts.infradead.org,
	linux-scsi@...r.kernel.org, mpt_linux_developer@....com,
	netdev@...r.kernel.org, osst-users@...ts.sourceforge.net,
	parisc-linux@...isc-linux.org, tpmdd-devel@...ts.sourceforge.net,
	uclinux-dist-devel@...ckfin.uclinux.org
Subject: Re: [PATCH] Prefix each line of multiline printk(KERN_<level>
 "foo\nbar") with KERN_<level>

On Sun, 26 Aug 2007, Geert Uytterhoeven wrote:

> What I mean is that probably there used to be a printk() call starting with
> `\n'. Then someone added a `KERN_ERR' in front of it.

 I gather '\n' at the beginning is to assure the following line is output 
on a separate line rather than as a continuation of another one which may 
have been output without a trailing '\n'.  A situation where printk() is 
called with a string containing no trailing '\n' may be discouraged, but 
there are some more or less justified exceptions.  For example the SCSI 
disk spin-up code is one.

 Therefore it may be reasonable for more critical messages -- perhaps not 
ones at KERN_ERR, but certainly KERN_CRIT and higher ones -- that may 
potentially happen asynchronously to start with '\n'.  In this case a call 
would look like this:

	printk("\n" KERN_CRIT "The actual message.\n");

Of course based on "console_loglevel" and "default_message_level" the 
leading '\n' may still get swallowed from what gets printed to the console 
terminal, but in reality I do not think that poses a problem, as these 
both can be set by a system administrator according to the local policy.

  Maciej
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