From: Heiko =?ISO-8859-1?Q?St=FCbner?= <heiko@sntech.de>
To: Julia Lawall <julia.lawall@lip6.fr>
Cc: Brian Norris <computersforpeace@gmail.com>,
        Julia Lawall <Julia.Lawall@lip6.fr>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org,
        Russell King - ARM Linux <linux@arm.linux.org.uk>,
        Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
        Andrew Lunn <andrew@lunn.ch>, Bjorn Helgaas <bhelgaas@google.com>,
        Jason Cooper <jason@lakedaemon.net>
Subject: Re: [PATCH 4/7] phy: rockchip-usb: add missing of_node_put
Date: Wed, 18 Nov 2015 21:40:37 +0100
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Hi Julia,

Am Mittwoch, 18. November 2015, 21:38:02 schrieb Julia Lawall:
> On Wed, 18 Nov 2015, Heiko St?bner wrote:
> > Am Mittwoch, 18. November 2015, 11:31:29 schrieb Brian Norris:
> > > On Wed, Nov 18, 2015 at 08:27:07PM +0100, Heiko St?bner wrote:
> > > > Am Montag, 16. November 2015, 12:33:17 schrieb Julia Lawall:
> > > > hmm, while I agree that the rockchip phy has an issue in the node
> > > > lifecycle, I'm not sure that patch fixes it fully.
> > > > 
> > > > It currently iterates over each phy, but would only of_node_put the
> > > > phy it
> > > > handled last. So if an error happens on the 3rd phy, the first 2 are
> > > > already instantiated and would also get removed when the overall probe
> > > > fails, but their of_node would never be "put".
> > > 
> > > Note the behavior of of_get_next_child() (and
> > > of_get_next_available_child()); it "Decrements the refcount of prev." So
> > > the loop only keeps a reference for (at most) one node at a time.
> > > 
> > > I believe Julia's patch is correct. It's possible the commit description
> > > could have made this aspect clearer though, since I was confused about
> > > this at first as well.
> > 
> > oh, I hadn't realized that :-) .
> > 
> > Although in this case, what happens with the last child, if only "prev"s
> > get decremented? When the loop finished I'd think that the last one would
> > keep it's reference, as the patch stand right - or I'm just blind.
> 
> The loop finishes when the child is NULL.  So there is nothing to put in
> that case.  The process of getting from the last child to the NULL does
> the of_node_put.

sorry for being a bit slow today ... I should probably sleep more :-)

Then the patch looks fine ... I'll add my Tag on the top, to not burry it down 
here.


Heiko


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