Re: assert in phylink.c with lan7801 and dp83tc811 since kernel 6.18

[Andrew Lunn <andrew@lunn.ch>]

On Wed, May 06, 2026 at 12:30:33PM +0000, Sven Schuchmann wrote:
> Hi Andrew,
> 
> I came up with this:
> 
> diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
> index 261af300ab00..734cb62a1043 100644
> --- a/drivers/net/usb/lan78xx.c
> +++ b/drivers/net/usb/lan78xx.c
> @@ -2862,7 +2862,9 @@ static int lan78xx_phylink_setup(struct lan78xx_net *dev)
>  static void lan78xx_phy_uninit(struct lan78xx_net *dev)
>  {
>         if (dev->phylink) {
> +               rtnl_lock();
>                 phylink_disconnect_phy(dev->phylink);
> +               rtnl_unlock();
>                 phylink_destroy(dev->phylink);
>                 dev->phylink = NULL;
>         }
> 
> and it seems to prevent the cash. What do you think?

Does the Ethernet also work?

As i said, there appears to be two things going on. For some reason it
decides the PHY and MAC don't make a valid combination and returns
-EINVAL.

And then we have the RTNL problem.

We should fix the RTNL problem, but that on its own will probably not
give you working Ethernet.

Right let me look at the context we are in when
phylink_disconnect_phy() is called. See if this fix is correct.

	Andrew