linux-kernel - Re: [PATCH] printk(): add KERN

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Message-Id: <20120409160803.27bc1376.akpm@linux-foundation.org>
Date:	Mon, 9 Apr 2012 16:08:03 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Kay Sievers <kay@...y.org>
Cc:	Joe Perches <joe@...ches.com>, linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Len Brown <lenb@...nel.org>
Subject: Re: [PATCH] printk(): add KERN_CONT where needed

On Tue, 3 Apr 2012 05:00:10 +0200
Kay Sievers <kay@...y.org> wrote:

> > Maybe it'd be better to aggregate content rather like
> > printk does. __Aggregate until you get a newline or a
> > new KERN_<LEVEL>
> 
> The continuation printk() can can always go wrong when multiple
> threads do that in parallel. We can try to make it better with a
> per-cpu buffer, but I guess there will always be a situation where
> this can happen.

Maybe we can be a bit smarter.  For example, if `current' is unchanged
and __builtin_return_address(0) is unchanged, keep on buffering.

It's all a bit hacky, but weeding out all those thousands of printks
which never get printed anyway doesn't sound much fun either.

> -	printk(")");
> +	printk(KERN_CONT ")");

And I do think we should avoid doing it that way, if only because it
consumes 10 display columns and makes a mess.  Maybe use pr_cont()? 
But that implies that the affected code is using the pr_foo()
facilities, and a lot of it doesn't.  So maybe a new macro.

All a bit of a pain.
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