• Vladimir Oltean's avatar
    net: dsa: lantiq_gswip: don't use devres for mdiobus · 0d120dfb
    Vladimir Oltean authored
    As explained in commits:
    74b6d7d1 ("net: dsa: realtek: register the MDIO bus under devres")
    5135e96a ("net: dsa: don't allocate the slave_mii_bus using devres")
    
    mdiobus_free() will panic when called from devm_mdiobus_free() <-
    devres_release_all() <- __device_release_driver(), and that mdiobus was
    not previously unregistered.
    
    The GSWIP switch is a platform device, so the initial set of constraints
    that I thought would cause this (I2C or SPI buses which call ->remove on
    ->shutdown) do not apply. But there is one more which applies here.
    
    If the DSA master itself is on a bus that calls ->remove from ->shutdown
    (like dpaa2-eth, which is on the fsl-mc bus), there is a device link
    between the switch and the DSA master, and device_links_unbind_consumers()
    will unbind the GSWIP switch driver on shutdown.
    
    So the same treatment must be applied to all DSA switch drivers, which
    is: either use devres for both the mdiobus allocation and registration,
    or don't use devres at all.
    
    The gswip driver has the code structure in place for orderly mdiobus
    removal, so just replace devm_mdiobus_alloc() with the non-devres
    variant, and add manual free where necessary, to ensure that we don't
    let devres free a still-registered bus.
    
    Fixes: ac3a68d5 ("net: phy: don't abuse devres in devm_mdiobus_register()")
    Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
    Reviewed-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
    Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
    0d120dfb
lantiq_gswip.c 62.7 KB