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net: asix: fix modprobe "sysfs: cannot create duplicate filename"

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"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: e532a096be ("net: usb: asix: ax88772: add phylib support")
Reported-by: Anton Lundin <glance@acc.umu.se>
Link: https://lore.kernel.org/netdev/20220623063649.GD23685@pengutronix.de/T/
Tested-by: Eizan Miyamoto <eizan@chromium.org>
Signed-off-by: Grant Grundler <grundler@chromium.org>
Link: https://lore.kernel.org/r/20230321170539.732147-1-grundler@chromium.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Grant Grundler 2023-03-21 10:05:39 -07:00 • committed by Jakub Kicinski
parent 68c3e4fc86
commit 8eac0095de
1 changed files with 27 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

32
drivers/net/usb/asix_devices.c
View file

@ -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);
}