linux-kernel - Re: [PATCH 2/2] net: macb: Unregister nedev before MDIO bus in remove

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Message-ID: <ZWOFMof7YMqGVl6f@shell.armlinux.org.uk>
Date:   Sun, 26 Nov 2023 17:49:38 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Claudiu Beznea <claudiu.beznea@...on.dev>,
        nicolas.ferre@...rochip.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        hkallweit1@...il.com, jgarzik@...ox.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] net: macb: Unregister nedev before MDIO bus in remove

On Sun, Nov 26, 2023 at 06:13:55PM +0100, Andrew Lunn wrote:
> > diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> > index cebae0f418f2..73d041af3de1 100644
> > --- a/drivers/net/ethernet/cadence/macb_main.c
> > +++ b/drivers/net/ethernet/cadence/macb_main.c
> > @@ -5165,11 +5165,11 @@ static void macb_remove(struct platform_device *pdev)
> >  
> >  	if (dev) {
> >  		bp = netdev_priv(dev);
> > +		unregister_netdev(dev);
> >  		phy_exit(bp->sgmii_phy);
> >  		mdiobus_unregister(bp->mii_bus);
> >  		mdiobus_free(bp->mii_bus);
> >  
> > -		unregister_netdev(dev);
> >  		tasklet_kill(&bp->hresp_err_tasklet);
> 
> 
> I don't know this driver...
> 
> What does this tasklet do? Is it safe for it to run after the netdev
> is unregistered, and the PHY and the mdio bus is gone? Maybe this
> tasklet_kill should be after the interrupt is disabled, but before the
> netdev is unregistered?

.. and while evaluating Andrew's comment, check whether the tasklet
is necessary for the device to successfully close or not - remembering
that unregister_netdev() will close down an open netdev.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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