linux-kernel - Re: [PATCH net-next 6/6] net: ethernet: fs

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Message-ID: <20240829104606.4ba68402@device-28.home>
Date: Thu, 29 Aug 2024 10:46:06 +0200
From: Maxime Chevallier <maxime.chevallier@...tlin.com>
To: Simon Horman <horms@...nel.org>
Cc: davem@...emloft.net, Pantelis Antoniou <pantelis.antoniou@...il.com>,
 Andrew Lunn <andrew@...n.ch>, Jakub Kicinski <kuba@...nel.org>, Eric
 Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Russell
 King <linux@...linux.org.uk>, Christophe Leroy
 <christophe.leroy@...roup.eu>, Florian Fainelli <f.fainelli@...il.com>,
 Heiner Kallweit <hkallweit1@...il.com>, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, thomas.petazzoni@...tlin.com, Herve Codina
 <herve.codina@...tlin.com>, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH net-next 6/6] net: ethernet: fs_enet: phylink conversion

Hello Simon,

On Wed, 28 Aug 2024 17:32:24 +0100
Simon Horman <horms@...nel.org> wrote:

> On Wed, Aug 28, 2024 at 11:51:02AM +0200, Maxime Chevallier wrote:
> > fs_enet is a quite old but still used Ethernet driver found on some NXP
> > devices. It has support for 10/100 Mbps ethernet, with half and full
> > duplex. Some variants of it can use RMII, while other integrations are
> > MII-only.
> > 
> > Add phylink support, thus removing custom fixed-link hanldling.
> > 
> > This also allows removing some internal flags such as the use_rmii flag.
> > 
> > Signed-off-by: Maxime Chevallier <maxime.chevallier@...tlin.com>  
> 
> Hi Maxime,
> 
> Some minor issues from my side: not a full review by any stretch of
> the imagination.
> 
> ...
> 
> > @@ -911,7 +894,7 @@ static int fs_enet_probe(struct platform_device *ofdev)
> >  	if (!IS_ERR(clk)) {
> >  		ret = clk_prepare_enable(clk);
> >  		if (ret)
> > -			goto out_deregister_fixed_link;
> > +			goto out_phylink;
> >  
> >  		fpi->clk_per = clk;
> >  	}  
> 
> This goto will result in a dereference of fep.
> But fep is not initialised until the following line,
> which appears a little below this hunk.
> 
> 	fep = netdev_priv(ndev);

Nice catch, the goto should rather go to out_free_fpi.

> 
> This goto will also result in the function returning without
> releasing clk.

ah yes, it's never disabled_unprepared, the phylink cleanup label is at
the wrong spot. I'll include a patch in the next iteration to make use
of devm_clk_get_enabled(), that should simplify all of that.

> Both flagged by Smatch.
> 
> > @@ -936,6 +919,26 @@ static int fs_enet_probe(struct platform_device *ofdev)
> >  	fep->fpi = fpi;
> >  	fep->ops = ops;
> >  
> > +	fep->phylink_config.dev = &ndev->dev;
> > +	fep->phylink_config.type = PHYLINK_NETDEV;
> > +	fep->phylink_config.mac_capabilities = MAC_10 | MAC_100;
> > +
> > +	__set_bit(PHY_INTERFACE_MODE_MII,
> > +		  fep->phylink_config.supported_interfaces);
> > +
> > +	if (of_device_is_compatible(ofdev->dev.of_node, "fsl,mpc5125-fec"))
> > +		__set_bit(PHY_INTERFACE_MODE_RMII,
> > +			  fep->phylink_config.supported_interfaces);
> > +
> > +	phylink = phylink_create(&fep->phylink_config, dev_fwnode(fep->dev),
> > +				 phy_mode, &fs_enet_phylink_mac_ops);
> > +	if (IS_ERR(phylink)) {
> > +		ret = PTR_ERR(phylink);
> > +		goto out_free_fpi;  
> 
> This also appears to leak clk, as well as ndev.

Thanks, will be addressed in V2.

> I didn't look for other cases.

I'll go over the cleanup path, thanks for checking this !

Thanks,

Maxime