net: dsa: ar9331: register the mdiobus under devres

BugLink: https://bugs.launchpad.net/bugs/1963889
[ Upstream commit 50facd86e9fbc4b93fe02e5fe05776047f45dbfb ]

As explained in commits:
74b6d7d13307 ("net: dsa: realtek: register the MDIO bus under devres")
5135e96a3dd2 ("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 ar9331 is an MDIO 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 ar9331 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 ar9331 driver doesn't have a complex code structure for mdiobus
removal, so just replace of_mdiobus_register with the devres variant in
order to be all-devres and ensure that we don't free a still-registered
bus.

Fixes: ac3a68d56651 ("net: phy: don't abuse devres in devm_mdiobus_register()")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/drivers/net/dsa/qca/ar9331.c b/drivers/net/dsa/qca/ar9331.c
index a6bfb6abc51a7dd9e3393043cc648bc6c8f5874d..5d476f452396c7c0173561fbc4186b62d9661e0d 100644 (file)
--- a/drivers/net/dsa/qca/ar9331.c
+++ b/drivers/net/dsa/qca/ar9331.c
@@ -378,7 +378,7 @@ static int ar9331_sw_mbus_init(struct ar9331_sw_priv *priv)
        if (!mnp)
                return -ENODEV;
 
-       ret = of_mdiobus_register(mbus, mnp);
+       ret = devm_of_mdiobus_register(dev, mbus, mnp);
        of_node_put(mnp);
        if (ret)
                return ret;
@@ -1093,7 +1093,6 @@ static void ar9331_sw_remove(struct mdio_device *mdiodev)
        }
 
        irq_domain_remove(priv->irqdomain);
-       mdiobus_unregister(priv->mbus);
        dsa_unregister_switch(&priv->ds);
 
        reset_control_assert(priv->sw_reset);