Date:   Thu, 9 Mar 2023 12:19:29 +0100
From:   Jiri Pirko <jiri@resnulli.us>
To:     Grant Grundler <grundler@chromium.org>
Cc:     Oleksij Rempel <linux@rempel-privat.de>,
        Pavel Skripkin <paskripkin@gmail.com>,
        Lukas Wunner <lukas@wunner.de>,
        Eizan Miyamoto <eizan@chromium.org>,
        Jakub Kicinski <kuba@kernel.org>,
        netdev <netdev@vger.kernel.org>,
        "David S . Miller" <davem@davemloft.net>,
        LKML <linux-kernel@vger.kernel.org>,
        Anton Lundin <glance@acc.umu.se>
Subject: Re: [PATCHv3 net 1/2] net: asix: fix modprobe "sysfs: cannot create
 duplicate filename"
Message-ID: <ZAnAwQ1LO81F6ssZ@nanopsycho>
References: <20230308202159.2419227-1-grundler@chromium.org>
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Wed, Mar 08, 2023 at 09:21:58PM CET, grundler@chromium.org wrote:
>"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 14:16 UTC:
>
>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: e532a096be0e ("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>

Reviewed-by: Jiri Pirko <jiri@nvidia.com>