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 = {
