linux-kernel - Re: [PATCH net-next] net: dsa: mv88e6xxx: fix unreleased fwnode_handle in setup

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Message-ID: <612445d2-d7c8-4bda-a070-e2c0ebbf3d4e@lunn.ch>
Date: Sun, 20 Oct 2024 16:47:07 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Javier Carrasco <javier.carrasco.cruz@...il.com>
Cc: Florian Fainelli <f.fainelli@...il.com>,
	Vladimir Oltean <olteanv@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Linus Walleij <linus.walleij@...aro.org>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] net: dsa: mv88e6xxx: fix unreleased
 fwnode_handle in setup_port()

On Sun, Oct 20, 2024 at 12:21:07AM +0200, Javier Carrasco wrote:
> On 19/10/2024 23:59, Andrew Lunn wrote:
> > On Sat, Oct 19, 2024 at 10:16:49PM +0200, Javier Carrasco wrote:
> >> 'ports_fwnode' is initialized via device_get_named_child_node(), which
> >> requires a call to fwnode_handle_put() when the variable is no longer
> >> required to avoid leaking memory.
> >>
> >> Add the missing fwnode_handle_put() after 'ports_fwnode' has been used
> >> and is no longer required.
> > 
> > As you point out, the handle is obtained with
> > device_get_named_child_node(). It seems odd to use a fwnode_ function
> > not a device_ function to release the handle. Is there a device_
> > function?
> > 
> > 	Andrew
> 
> 
> Hi Andrew,
> 
> device_get_named_child_node() receives a pointer to a *device*, and
> returns a child node (a pointer to an *fwnode_handle*). That is what has
> to be released, and therefore fwnode_handle_put() is the right one.
> 
> Note that device_get_named_child_node() documents how to release the
> fwnode pointer:
> 
> "The caller is responsible for calling fwnode_handle_put() on the
> returned fwnode pointer."

O.K. I just don't like asymmetric APIs. They often lead to bugs, just
look wrong, and make reviewers ask questions...

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew