This is a note to let you know that I've just added the patch titled net: dsa: seville: register the mdiobus under devres to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-dsa-seville-register-the-mdiobus-under-devres.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 2e8b1dea4d89b51d8a7b247c961a4f8ecf40c208 Author: Vladimir Oltean <vladimir.oltean@xxxxxxx> Date: Mon Feb 7 18:15:51 2022 +0200 net: dsa: seville: register the mdiobus under devres [ Upstream commit bd488afc3b39e045ba71aab472233f2a78726e7b ] 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 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: ac3a68d56651 ("net: phy: don't abuse devres in devm_mdiobus_register()") Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx> Reviewed-by: Florian Fainelli <f.fainelli@xxxxxxxxx> Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/dsa/ocelot/seville_vsc9953.c b/drivers/net/dsa/ocelot/seville_vsc9953.c index ca8c003b99bc5..05e4e75c01076 100644 --- a/drivers/net/dsa/ocelot/seville_vsc9953.c +++ b/drivers/net/dsa/ocelot/seville_vsc9953.c @@ -1111,7 +1111,7 @@ static int vsc9953_mdio_bus_alloc(struct ocelot *ocelot) snprintf(bus->id, MII_BUS_ID_SIZE, "%s-imdio", dev_name(dev)); /* 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; @@ -1163,7 +1163,8 @@ static void vsc9953_mdio_bus_free(struct ocelot *ocelot) mdio_device_free(pcs->mdio); lynx_pcs_destroy(pcs); } - mdiobus_unregister(felix->imdio); + + /* mdiobus_unregister and mdiobus_free handled by devres */ } static const struct felix_info seville_info_vsc9953 = {