linux-kernel - Re: [PATCH 4/7] phy: rockchip-usb: add missing of_node

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Message-ID: <5404117.o251jAaic5@diego>
Date:	Wed, 18 Nov 2015 21:40:37 +0100
From:	Heiko Stübner <heiko@...ech.de>
To:	Julia Lawall <julia.lawall@...6.fr>
Cc:	Brian Norris <computersforpeace@...il.com>,
	Julia Lawall <Julia.Lawall@...6.fr>,
	Kishon Vijay Abraham I <kishon@...com>,
	kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Andrew Lunn <andrew@...n.ch>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Jason Cooper <jason@...edaemon.net>
Subject: Re: [PATCH 4/7] phy: rockchip-usb: add missing of_node_put

Hi Julia,

Am Mittwoch, 18. November 2015, 21:38:02 schrieb Julia Lawall:
> On Wed, 18 Nov 2015, Heiko Stübner wrote:
> > Am Mittwoch, 18. November 2015, 11:31:29 schrieb Brian Norris:
> > > On Wed, Nov 18, 2015 at 08:27:07PM +0100, Heiko Stübner 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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