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net: dsa: seville: register the mdiobus under devres

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As explained in commits:
74b6d7d133 ("net: dsa: realtek: register the MDIO bus under devres")
5135e96a3d ("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 Seville VSC9959 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 seville 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 seville driver has a code structure that could accommodate both the
mdiobus_unregister and mdiobus_free calls, but it has an external
dependency upon mscc_miim_setup() from mdio-mscc-miim.c, which calls
devm_mdiobus_alloc_size() on its behalf. So rather than restructuring
that, and exporting yet one more symbol mscc_miim_teardown(), let's work
with devres and replace of_mdiobus_register with the devres variant.
When we use all-devres, we can ensure that devres doesn't free a
still-registered bus (it either runs both callbacks, or none).

Fixes: ac3a68d566 ("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 18:15:51 +02:00 committed by Jakub Kicinski
parent 209bdb7ec6
commit bd488afc3b
1 changed files with 3 additions and 2 deletions
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5
drivers/net/dsa/ocelot/seville_vsc9953.c
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@ -1029,7 +1029,7 @@ static int vsc9953_mdio_bus_alloc(struct ocelot *ocelot)
}
/* Needed in order to initialize the bus mutex lock */
rc = of_mdiobus_register(bus, NULL);
rc = devm_of_mdiobus_register(dev, bus, NULL);
if (rc < 0) {
dev_err(dev, "failed to register MDIO bus\n");
return rc;
@ -1083,7 +1083,8 @@ static void vsc9953_mdio_bus_free(struct ocelot *ocelot)
mdio_device_free(mdio_device);
lynx_pcs_destroy(phylink_pcs);
}
mdiobus_unregister(felix->imdio);
/* mdiobus_unregister and mdiobus_free handled by devres */
}
static const struct felix_info seville_info_vsc9953 = {