linux-kernel - Re: [RFC PATCH net-next 2/3] net: dsa: destroy the phylink instance on any error in dsa_slave_phy

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Date:   Thu, 2 Sep 2021 13:25:26 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Vladimir Oltean <vladimir.oltean@....com>
Cc:     netdev@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Alvin Šipraga <alsi@...g-olufsen.dk>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        kernel-team <kernel-team@...roid.com>,
        Len Brown <lenb@...nel.org>
Subject: Re: [RFC PATCH net-next 2/3] net: dsa: destroy the phylink instance
 on any error in dsa_slave_phy_setup

On Thu, Sep 02, 2021 at 01:50:52AM +0300, Vladimir Oltean wrote:
> DSA supports connecting to a phy-handle, and has a fallback to a non-OF
> based method of connecting to an internal PHY on the switch's own MDIO
> bus, if no phy-handle and no fixed-link nodes were present.
> 
> The -ENODEV error code from the first attempt (phylink_of_phy_connect)
> is what triggers the second attempt (phylink_connect_phy).
> 
> However, when the first attempt returns a different error code than
> -ENODEV, this results in an unbalance of calls to phylink_create and
> phylink_destroy by the time we exit the function. The phylink instance
> has leaked.
> 
> There are many other error codes that can be returned by
> phylink_of_phy_connect. For example, phylink_validate returns -EINVAL.
> So this is a practical issue too.
> 
> Fixes: aab9c4067d23 ("net: dsa: Plug in PHYLINK support")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
> ---
> I know, I will send this bug fix to "net" too, this is provided just for
> testing purposes, and for the completeness of the patch set.

Probably should have been the first patch of the set. This looks
absolutely correct to me. Please send for the net tree.

Reviewed-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

Thanks.

-- 
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