linux-kernel - RE: [PATCH net v2] net: emaclite: Add error handling for of_address_ and _mdio

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Message-ID: <BYAPR02MB5638EDA3D13A272ACF599BBFC7C40@BYAPR02MB5638.namprd02.prod.outlook.com>
Date:   Thu, 17 Dec 2020 18:23:49 +0000
From:   Radhey Shyam Pandey <radheys@...inx.com>
To:     Denis Kirjanov <kda@...ux-powerpc.org>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "kuba@...nel.org" <kuba@...nel.org>,
        Michal Simek <michals@...inx.com>,
        "mchehab+samsung@...nel.org" <mchehab+samsung@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "nicolas.ferre@...rochip.com" <nicolas.ferre@...rochip.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        git <git@...inx.com>, Shravya Kumbham <shravyak@...inx.com>
Subject: RE: [PATCH net v2] net: emaclite: Add error handling for of_address_
 and _mdio_setup functions

> -----Original Message-----
> From: Denis Kirjanov <kda@...ux-powerpc.org>
> Sent: Tuesday, November 17, 2020 6:43 PM
> To: Radhey Shyam Pandey <radheys@...inx.com>
> Cc: davem@...emloft.net; netdev@...r.kernel.org; kuba@...nel.org;
> Michal Simek <michals@...inx.com>; mchehab+samsung@...nel.org;
> gregkh@...uxfoundation.org; nicolas.ferre@...rochip.com; linux-arm-
> kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; git
> <git@...inx.com>; Shravya Kumbham <shravyak@...inx.com>
> Subject: Re: [PATCH net v2] net: emaclite: Add error handling for
> of_address_ and _mdio_setup functions
> 
> On 11/17/20, Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
> wrote:
> > From: Shravya Kumbham <shravya.kumbham@...inx.com>
> >
> > Add ret variable, condition to check the return value and error path
> > for the of_address_to_resource() function. It also adds error handling
> > for mdio setup and decrement refcount of phy node.
> >
> > Addresses-Coverity: Event check_return value.
> > Signed-off-by: Shravya Kumbham <shravya.kumbham@...inx.com>
> > Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
> > ---
> > Changes for v2:
> >
> > - Change subject_prefix to target net tree.
> > - Add error handling for mdio_setup and remove phy_read changes.
> >   Error checking of phy_read will be added along with phy_write
> >   in a followup patch. Document the changes in commit description.
> > ---
> >  drivers/net/ethernet/xilinx/xilinx_emaclite.c | 16 +++++++++++++---
> >  1 file changed, 13 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/xilinx/xilinx_emaclite.c
> > b/drivers/net/ethernet/xilinx/xilinx_emaclite.c
> > index 0c26f5bcc523..4e0005164785 100644
> > --- a/drivers/net/ethernet/xilinx/xilinx_emaclite.c
> > +++ b/drivers/net/ethernet/xilinx/xilinx_emaclite.c
> > @@ -820,7 +820,7 @@ static int xemaclite_mdio_write(struct mii_bus
> > *bus, int phy_id, int reg,  static int xemaclite_mdio_setup(struct
> > net_local *lp, struct device *dev)  {
> >  	struct mii_bus *bus;
> > -	int rc;
> > +	int rc, ret;
> >  	struct resource res;
> >  	struct device_node *np = of_get_parent(lp->phy_node);
> >  	struct device_node *npp;
> > @@ -834,7 +834,12 @@ static int xemaclite_mdio_setup(struct net_local
> > *lp, struct device *dev)
> >  	}
> >  	npp = of_get_parent(np);
> >
> > -	of_address_to_resource(npp, 0, &res);
> > +	ret = of_address_to_resource(npp, 0, &res);
> > +	if (ret) {
> > +		dev_err(dev, "%s resource error!\n",
> > +			dev->of_node->full_name);
> > +		return ret;
> > +	}
> 
> npp is not returned to of_node_put() in the error case below

Yes, agree. The ref counting of npp device node is broken. 
I am planning to send v3 with a separate patch to simplify
this.

[1/2] net: emaclite: Simplify device node ref counting
[2/2] net: emaclite: Add error handling for of_address_
to_resource and xemaclite_mdio_setup functions

> 
> >  	if (lp->ndev->mem_start != res.start) {
> >  		struct phy_device *phydev;
> >  		phydev = of_phy_find_device(lp->phy_node); @@ -1173,7
> +1178,11 @@
> > static int xemaclite_of_probe(struct platform_device
> > *ofdev)
> >  	xemaclite_update_address(lp, ndev->dev_addr);
> >
> >  	lp->phy_node = of_parse_phandle(ofdev->dev.of_node, "phy-
> handle", 0);
> > -	xemaclite_mdio_setup(lp, &ofdev->dev);
> > +	rc = xemaclite_mdio_setup(lp, &ofdev->dev);
> > +	if (rc) {
> > +		dev_warn(dev, "error registering MDIO bus: %d\n", rc);
> > +		goto error;
> > +	}
> >
> >  	dev_info(dev, "MAC address is now %pM\n", ndev->dev_addr);
> >
> > @@ -1197,6 +1206,7 @@ static int xemaclite_of_probe(struct
> > platform_device
> > *ofdev)
> >  	return 0;
> >
> >  error:
> > +	of_node_put(lp->phy_node);
> >  	free_netdev(ndev);
> >  	return rc;
> >  }
> > --
> > 2.7.4
> >
> >