netdev - Re: [PATCH] net: dsa: Add of_node_put() before break statement

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Date:   Sun, 23 Aug 2020 16:28:37 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Sumera Priyadarsini <sylphrenadin@...il.com>
Cc:     davem@...emloft.net, Julia.Lawall@...6.fr, sean.wang@...iatek.com,
        vivien.didelot@...il.com, f.fainelli@...il.com, kuba@...nel.org,
        matthias.bgg@...il.com, netdev@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: dsa: Add of_node_put() before break statement

On Sun, Aug 23, 2020 at 07:31:16PM +0530, Sumera Priyadarsini wrote:
> Every iteration of for_each_child_of_node() decrements
> the reference count of the previous node, however when control
> is transferred from the middle of the loop, as in the case of
> a return or break or goto, there is no decrement thus ultimately
> resulting in a memory leak.
> 
> Fix a potential memory leak in mt7530.c by inserting of_node_put()
> before the break statement.
> 
> Issue found with Coccinelle.
> 
> Signed-off-by: Sumera Priyadarsini <sylphrenadin@...il.com>
> ---
>  drivers/net/dsa/mt7530.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index 8dcb8a49ab67..af83e5034842 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -1334,6 +1334,7 @@ mt7530_setup(struct dsa_switch *ds)
>  				if (id == 4)
>  					priv->p5_intf_sel = P5_INTF_SEL_PHY_P4;
>  			}
> +			of_node_put(mac_np);
>  			of_node_put(phy_node);
>  			break;
>  		}

Within the same loop is:

                       if (phy_node->parent == priv->dev->of_node->parent) {
                                ret = of_get_phy_mode(mac_np, &interface);
                                if (ret && ret != -ENODEV)
                                        return ret;


shouldn't this also have a put?

	  Andrew