linux-kernel - Re: [PATCH] drivers: regmap: bugfix in regcache-rbtree.c

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Message-ID: <20130821162400.66c5b52e@archvile>
Date:	Wed, 21 Aug 2013 16:24:00 +0200
From:	David Jander <david.jander@...tonic.nl>
To:	Mark Brown <broonie@...nel.org>
Cc:	Dimitris Papastamos <dp@...nsource.wolfsonmicro.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers: regmap: bugfix in regcache-rbtree.c

On Wed, 21 Aug 2013 15:08:16 +0100
Mark Brown <broonie@...nel.org> wrote:

> On Wed, Aug 21, 2013 at 03:14:23PM +0200, David Jander wrote:
> 
> > Here's the explanation:
> 
> > 1. If a driver initializes a regmap with a RB-tree cache, and starts
> > writing to registers in some arbitrary order, you might get overlapping
> > rbnodes: Suppose I have this rb-tree (a real case I happen to have):
> 
> > # cat /sys/kernel/debug/regmap/1-000a/rbtree
> > 2-19 (24)
> > 4-1b (24)
> 
> Like I say this isn't supposed to be the case in the first place, those
> two nodes should be being merged - what we need to understand is where
> the overlapping nodes came from.

As I said in my last e-mail just a few seconds ago, it does happen when:

1. 4-1b is cached and 2-19 isn't yet.

2. A write access to register 2 occurs.

Hope this helps.

Best regards,

-- 
David Jander
Protonic Holland.
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