linux-kernel - Re: [PATCH net v1] net: phy: Change flag to autoremove the consumer

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Message-ID: <20250704142138.3f1a4ec1@fedora.home>
Date: Fri, 4 Jul 2025 14:21:38 +0200
From: Maxime Chevallier <maxime.chevallier@...tlin.com>
To: Sarosh Hasan <quic_sarohasa@...cinc.com>
Cc: Wei Fang <wei.fang@....com>, "andrew @ lunn . ch" <andrew@...n.ch>,
 Russell King <linux@...linux.org.uk>, Florian Fainelli
 <f.fainelli@...il.com>, "hkallweit1 @ gmail . com" <hkallweit1@...il.com>,
 "davem @ davemloft . net" <davem@...emloft.net>, "edumazet @ google . com"
 <edumazet@...gle.com>, "kuba @ kernel . org" <kuba@...nel.org>, "pabeni @
 redhat . com" <pabeni@...hat.com>, "xiaolei . wang @ windriver . com"
 <xiaolei.wang@...driver.com>, "linux-kernel @ vger . kernel . org"
 <linux-kernel@...r.kernel.org>, "imx @ lists . linux . dev"
 <imx@...ts.linux.dev>, "netdev @ vger . kernel . org"
 <netdev@...r.kernel.org>, Prasad Sodagudi <quic_psodagud@...cinc.com>,
 Abhishek Chauhan <quic_abchauha@...cinc.com>, Sagar Cheluvegowda
 <quic_scheluve@...cinc.com>, Girish Potnuru <quic_gpotnuru@...cinc.com>,
 <kernel@....qualcomm.com>
Subject: Re: [PATCH net v1] net: phy: Change flag to autoremove the consumer

On Thu, 3 Jul 2025 14:30:41 +0530
Sarosh Hasan <quic_sarohasa@...cinc.com> wrote:

> phy_detach() is not called when the MDIO controller driver is
> removed. So phydev->devlink is not cleared, but actually the device
> link has been removed by phy_device_remove()--> device_del().Therefore,
> it will cause the crash when the MAC controller driver is removed.
> In such case delete link between phy dev and mac dev. Change the 
> DL_FLAG_STATELESS flag to DL_FLAG_AUTOREMOVE_SUPPLIER,so that the
> consumer (MAC controller) driver will be automatically removed
> when the link is removed.

This doesn't work unfortunately, PHY devices can be hot-swappable, e.g.
when the PHY is in an SFP module. In that case, we must not
automatically remove the MAC controller driver when the PHY goes away.

I gave this patch a quick test on a Macchiatobin, which has an SFP
module, and indeed when you unplug the module while the link is up, the
system hangs completely when running a command like "ip a" afterwards.

Maxime