netdev - Re: [PATCH net] net: phy: Warn if phy is attached when removing

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Message-ID: <20220818102443.4c7c50e8@kernel.org>
Date:   Thu, 18 Aug 2022 10:24:43 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Sean Anderson <sean.anderson@...o.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>, netdev@...r.kernel.org,
        Paolo Abeni <pabeni@...hat.com>,
        "David S . Miller" <davem@...emloft.net>,
        linux-kernel@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        Vladimir Oltean <olteanv@...il.com>
Subject: Re: [PATCH net] net: phy: Warn if phy is attached when removing

On Tue, 16 Aug 2022 12:37:01 -0400 Sean Anderson wrote:
> netdevs using phylib can be oopsed from userspace in the following
> manner:
> 
> $ ip link set $iface up
> $ echo $(basename $(readlink /sys/class/net/$iface/phydev)) > \
>       /sys/class/net/$iface/phydev/driver/unbind
> $ ip link set $iface down
> 
> However, the traceback provided is a bit too late, since it does not
> capture the root of the problem (unbinding the driver). It's also
> possible that the memory has been reallocated if sufficient time passes
> between when the phy is detached and when the netdev touches the phy
> (which could result in silent memory corruption). Add a warning at the
> source of the problem. A future patch could make this more robust by
> calling dev_close.

Hm, so we're adding the warning to get more detailed reports "from the
field"? Guess we've all done that, so fair.

Acks? It can still make -rc2 if that matters...