linux-kernel - Re: [PATCH v4 1/8] [media] soc_camera: Do not decrement endpoint node refcount in the loop

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Message-ID: <20140929165937.GB13163@kroah.com>
Date:	Mon, 29 Sep 2014 12:59:37 -0400
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Philipp Zabel <p.zabel@...gutronix.de>
Cc:	Dan Carpenter <dan.carpenter@...cle.com>,
	Mauro Carvalho Chehab <m.chehab@...sung.com>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	kernel@...gutronix.de, Grant Likely <grant.likely@...aro.org>,
	Russell King <rmk+kernel@....linux.org.uk>,
	Guennadi Liakhovetski <g.liakhovetski@....de>,
	linux-media@...r.kernel.org
Subject: Re: [PATCH v4 1/8] [media] soc_camera: Do not decrement endpoint
 node refcount in the loop

On Mon, Sep 29, 2014 at 11:45:23AM +0200, Philipp Zabel wrote:
> Am Montag, den 29.09.2014, 12:13 +0300 schrieb Dan Carpenter:
> > On Mon, Sep 29, 2014 at 10:15:44AM +0200, Philipp Zabel wrote:
> > > In preparation for a following patch, stop decrementing the endpoint node
> > > refcount in the loop. This temporarily leaks a reference to the endpoint node,
> > > which will be fixed by having of_graph_get_next_endpoint decrement the refcount
> > > of its prev argument instead.
> > 
> > Don't do this...
> > 
> > My understanding (and I haven't invested much time into trying to
> > understand this beyond glancing at the change) is that patch 1 and 2,
> > introduce small bugs that are fixed in patch 3?
> >
> > Just fold all three patches into one patch.  We need an Ack from Mauro
> > and Greg and then send the patch through Grant's tree.
> 
> Yes. Patches 1 and 2 leak a reference on of_nodes touched by the loop.
> As far as I am aware, all users of this code don't use the reference
> counting (CONFIG_OF_DYNAMIC is disabled), so this bug should be
> theoretical.
> 
> I'd be happy do as you suggest if Mauro and Greg agree.

Let's see the correct patch, don't break things and then later on fix
them...

thanks,

greg k-h
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