Commit 8eac0095 authored by Grant Grundler's avatar Grant Grundler Committed by Jakub Kicinski
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net: asix: fix modprobe "sysfs: cannot create duplicate filename" 



"modprobe asix ; rmmod asix ; modprobe asix" fails with:
   sysfs: cannot create duplicate filename \
   	'/devices/virtual/mdio_bus/usb-003:004'

Issue was originally reported by Anton Lundin on 2022-06-22 (link below).

Chrome OS team hit the same issue in Feb, 2023 when trying to find
work arounds for other issues with AX88172 devices.

The use of devm_mdiobus_register() with usbnet devices results in the
MDIO data being associated with the USB device. When the asix driver
is unloaded, the USB device continues to exist and the corresponding
"mdiobus_unregister()" is NOT called until the USB device is unplugged
or unauthorized. So the next "modprobe asix" will fail because the MDIO
phy sysfs attributes still exist.

The 'easy' (from a design PoV) fix is to use the non-devm variants of
mdiobus_* functions and explicitly manage this use in the asix_bind
and asix_unbind function calls. I've not explored trying to fix usbnet
initialization so devm_* stuff will work.

Fixes: e532a096 ("net: usb: asix: ax88772: add phylib support")
Reported-by: default avatarAnton Lundin <glance@acc.umu.se>
Link: https://lore.kernel.org/netdev/20220623063649.GD23685@pengutronix.de/T/


Tested-by: default avatarEizan Miyamoto <eizan@chromium.org>
Signed-off-by: default avatarGrant Grundler <grundler@chromium.org>
Link: https://lore.kernel.org/r/20230321170539.732147-1-grundler@chromium.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 68c3e4fc

drivers/net/usb/asix_devices.c

+27 −5
Original line number Diff line number Diff line
@@ -666,8 +666,9 @@ static int asix_resume(struct usb_interface *intf) 
static int ax88772_init_mdio(struct usbnet *dev)

{

	struct asix_common_private *priv = dev->driver_priv;

	int ret;



	priv->mdio = devm_mdiobus_alloc(&dev->udev->dev);

	priv->mdio = mdiobus_alloc();

	if (!priv->mdio)

		return -ENOMEM;
@@ -679,7 +680,20 @@ static int ax88772_init_mdio(struct usbnet *dev) 
	snprintf(priv->mdio->id, MII_BUS_ID_SIZE, "usb-%03d:%03d",

		 dev->udev->bus->busnum, dev->udev->devnum);



	return devm_mdiobus_register(&dev->udev->dev, priv->mdio);

	ret = mdiobus_register(priv->mdio);

	if (ret) {

		netdev_err(dev->net, "Could not register MDIO bus (err %d)\n", ret);

		mdiobus_free(priv->mdio);

		priv->mdio = NULL;

	}



	return ret;

}



static void ax88772_mdio_unregister(struct asix_common_private *priv)

{

	mdiobus_unregister(priv->mdio);

	mdiobus_free(priv->mdio);

}



static int ax88772_init_phy(struct usbnet *dev)
@@ -896,16 +910,23 @@ static int ax88772_bind(struct usbnet *dev, struct usb_interface *intf) 


	ret = ax88772_init_mdio(dev);

	if (ret)

		return ret;

		goto mdio_err;



	ret = ax88772_phylink_setup(dev);

	if (ret)

		return ret;

		goto phylink_err;



	ret = ax88772_init_phy(dev);

	if (ret)

		phylink_destroy(priv->phylink);

		goto initphy_err;



	return 0;



initphy_err:

	phylink_destroy(priv->phylink);

phylink_err:

	ax88772_mdio_unregister(priv);

mdio_err:

	return ret;

}
@@ -926,6 +947,7 @@ static void ax88772_unbind(struct usbnet *dev, struct usb_interface *intf) 
	phylink_disconnect_phy(priv->phylink);

	rtnl_unlock();

	phylink_destroy(priv->phylink);

	ax88772_mdio_unregister(priv);

	asix_rx_fixup_common_free(dev->driver_priv);

}