[PATCH 5.10 069/116] net: dsa: mv88e6xxx: dont use devres for mdiobus

Greg Kroah-Hartman
2022-02-14T09:57:02Z

From: Vladimir Oltean <vladimir.oltean@nxp.com>

[ Upstream commit f53a2ce893b2c7884ef94471f170839170a4eba0 ]

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 mv88e6xxx 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 Marvell switch driver on shutdown.

systemd-shutdown[1]: Powering off.
mv88e6085 0x0000000008b96000:00 sw_gl0: Link is Down
fsl-mc dpbp.9: Removing from iommu group 7
fsl-mc dpbp.8: Removing from iommu group 7
------------[ cut here ]------------
kernel BUG at drivers/net/phy/mdio_bus.c:677!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 5.16.5-00040-gdc05f73788e5 #15
pc : mdiobus_free+0x44/0x50
lr : devm_mdiobus_free+0x10/0x20
Call trace:
mdiobus_free+0x44/0x50
devm_mdiobus_free+0x10/0x20
devres_release_all+0xa0/0x100
__device_release_driver+0x190/0x220
device_release_driver_internal+0xac/0xb0
device_links_unbind_consumers+0xd4/0x100
__device_release_driver+0x4c/0x220
device_release_driver_internal+0xac/0xb0
device_links_unbind_consumers+0xd4/0x100
__device_release_driver+0x94/0x220
device_release_driver+0x28/0x40
bus_remove_device+0x118/0x124
device_del+0x174/0x420
fsl_mc_device_remove+0x24/0x40
__fsl_mc_device_remove+0xc/0x20
device_for_each_child+0x58/0xa0
dprc_remove+0x90/0xb0
fsl_mc_driver_remove+0x20/0x5c
__device_release_driver+0x21c/0x220
device_release_driver+0x28/0x40
bus_remove_device+0x118/0x124
device_del+0x174/0x420
fsl_mc_bus_remove+0x80/0x100
fsl_mc_bus_shutdown+0xc/0x1c
platform_shutdown+0x20/0x30
device_shutdown+0x154/0x330
kernel_power_off+0x34/0x6c
__do_sys_reboot+0x15c/0x250
__arm64_sys_reboot+0x20/0x30
invoke_syscall.constprop.0+0x4c/0xe0
do_el0_svc+0x4c/0x150
el0_svc+0x24/0xb0
el0t_64_sync_handler+0xa8/0xb0
el0t_64_sync+0x178/0x17c

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 Marvell driver already has a good structure for mdiobus removal, so
just plug in mdiobus_free and get rid of devres.

Fixes: ac3a68d56651 ("net: phy: don't abuse devres in devm_mdiobus_register()")
Reported-by: Rafael Richter <Rafael.Richter@gin.de>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Daniel Klauer <daniel.klauer@gin.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/dsa/mv88e6xxx/chip.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index afc5500ef8ed9..9b451b820d7a6 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -3072,7 +3072,7 @@ static int mv88e6xxx_mdio_register(struct mv88e6xxx_chip *chip,
return err;
}

- bus = devm_mdiobus_alloc_size(chip->dev, sizeof(*mdio_bus));
+ bus = mdiobus_alloc_size(sizeof(*mdio_bus));
if (!bus)
return -ENOMEM;

@@ -3097,14 +3097,14 @@ static int mv88e6xxx_mdio_register(struct mv88e6xxx_chip *chip,
if (!external) {
err = mv88e6xxx_g2_irq_mdio_setup(chip, bus);
if (err)
- return err;
+ goto out;
}

err = of_mdiobus_register(bus, np);
if (err) {
dev_err(chip->dev, "Cannot register MDIO bus (%d)\n", err);
mv88e6xxx_g2_irq_mdio_free(chip, bus);
- return err;
+ goto out;
}

if (external)
@@ -3113,6 +3113,10 @@ static int mv88e6xxx_mdio_register(struct mv88e6xxx_chip *chip,
list_add(&mdio_bus->list, &chip->mdios);

return 0;
+
+out:
+ mdiobus_free(bus);
+ return err;
}

static void mv88e6xxx_mdios_unregister(struct mv88e6xxx_chip *chip)
@@ -3128,6 +3132,7 @@ static void mv88e6xxx_mdios_unregister(struct mv88e6xxx_chip *chip)
mv88e6xxx_g2_irq_mdio_free(chip, bus);

mdiobus_unregister(bus);
+ mdiobus_free(bus);
}
}

--
2.34.1