Date: Mon, 08 Apr 2002 19:14:44 -0700
From: "Martin J. Bligh" <Martin.Bligh@us.ibm.com>
Reply-To: "Martin J. Bligh" <Martin.Bligh@us.ibm.com>
To: Andrew Morton <akpm@zip.com.au>
cc: linux-kernel@vger.kernel.org, Tony.P.Lee@nokia.com, kessler@us.ibm.com,
        alan@lxorguk.ukuu.org.uk, Dave Jones <davej@suse.de>
Subject: Re: Event logging vs enhancing printk
Message-ID: <1934841354.1018293283@[10.10.2.3]>
In-Reply-To: <3CB222AB.64005F3B@zip.com.au>
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> Ah.  Yes, that will definitely happen.  We only have atomicity
> at the level of a single printk call.
> 
> It would be feasible to introduce additional locking so that
> multiple printks can be made atomic.  This should be resisted
> though - printk needs to be really robust, and needs to have
> a good chance of working even when the machine is having hysterics.
> It's already rather complex.
> 
> For the rare cases which you cite we can use a local staging
> buffer and sprintf, or just live with it, I suspect.

Right - what I'm proposing would be a generic equivalent of the
local staging buffer and sprintf - basically just a little wrapper
that does this for you, keeping a per task buffer somewhere.

The reason I want to do it like this, rather than what you suggest,
is that there are over 5000 of these "rare cases" of a printk without
a newline, according to the IBM RAS group's code search ;-) I don't
fancy changing that for 5000 instances (obviously some of those are
grouped together, but the count is definitely non-trivial). I'd 
attach the report they sent me, but it's 657K long ;-) 

M.

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