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net: dsa: bcm_sf2: don't use devres for mdiobus

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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 Starfighter 2 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 bcm_sf2 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 bcm_sf2 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: 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>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Vladimir Oltean 2022-02-07 18:15:49 +02:00 committed by Jakub Kicinski
parent 50facd86e9
commit 08f1a20822
1 changed files with 5 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/net/dsa/bcm_sf2.c
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@ -621,7 +621,7 @@ static int bcm_sf2_mdio_register(struct dsa_switch *ds)
get_device(&priv->master_mii_bus->dev);
priv->master_mii_dn = dn;
priv->slave_mii_bus = devm_mdiobus_alloc(ds->dev);
priv->slave_mii_bus = mdiobus_alloc();
if (!priv->slave_mii_bus) {
of_node_put(dn);
return -ENOMEM;
@ -681,8 +681,10 @@ static int bcm_sf2_mdio_register(struct dsa_switch *ds)
}
err = mdiobus_register(priv->slave_mii_bus);
if (err && dn)
if (err && dn) {
mdiobus_free(priv->slave_mii_bus);
of_node_put(dn);
}
return err;
}
@ -690,6 +692,7 @@ static int bcm_sf2_mdio_register(struct dsa_switch *ds)
static void bcm_sf2_mdio_unregister(struct bcm_sf2_priv *priv)
{
mdiobus_unregister(priv->slave_mii_bus);
mdiobus_free(priv->slave_mii_bus);
of_node_put(priv->master_mii_dn);
}