linux-kernel - Re: [PATCH] Fix rq->lock vs logbuf

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Message-ID: <1361355555.10155.14.camel@laptop>
Date:	Wed, 20 Feb 2013 11:19:15 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	"Bu, Yitian" <ybu@....qualcomm.com>
Cc:	"tglx@...utronix.de" <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...nel.org" <mingo@...nel.org>
Subject: Re: [PATCH] Fix rq->lock vs logbuf_lock unlock race

On Wed, 2013-02-20 at 09:38 +0000, Bu, Yitian wrote:
> 
> 2. from printk comment: "This is printk(). It can be called from any
> context. 
> We want it to work. ". I suppose to use printk in any context.

Unfortunately that's not quite possible, rq->lock is really out of
bounds. At one point I tried 'fixing' this but there's a whole bunch of
nasty that's not going to go away.

I've since forgotten most of the details, but aside from logbuf problems
there's a whole host of issues with the console drivers themselves as
well.

If you really want to do this, use early_printk.

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