Alexander Sverdlin 5a22fbcc10 net: dsa: lan9303: consequently nested-lock physical MDIO ... When LAN9303 is MDIO-connected two callchains exist into mdio->bus->write(): 1. switch ports 1&2 ("physical" PHYs): virtual (switch-internal) MDIO bus (lan9303_switch_ops->phy_{read|write})-> lan9303_mdio_phy_{read|write} -> mdiobus_{read|write}_nested 2. LAN9303 virtual PHY: virtual MDIO bus (lan9303_phy_{read|write}) -> lan9303_virt_phy_reg_{read|write} -> regmap -> lan9303_mdio_{read|write} If the latter functions just take mutex_lock(&sw_dev->device->bus->mdio_lock) it triggers a LOCKDEP false-positive splat. It's false-positive because the first mdio_lock in the second callchain above belongs to virtual MDIO bus, the second mdio_lock belongs to physical MDIO bus. Consequent annotation in lan9303_mdio_{read|write} as nested lock (similar to lan9303_mdio_phy_{read|write}, it's the same physical MDIO bus) prevents the following splat: WARNING: possible circular locking dependency detected 5.15.71 #1 Not tainted ------------------------------------------------------ kworker/u4:3/609 is trying to acquire lock: ffff000011531c68 (lan9303_mdio:131:(&lan9303_mdio_regmap_config)->lock){+.+.}-{3:3}, at: regmap_lock_mutex but task is already holding lock: ffff0000114c44d8 (&bus->mdio_lock){+.+.}-{3:3}, at: mdiobus_read which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&bus->mdio_lock){+.+.}-{3:3}: lock_acquire __mutex_lock mutex_lock_nested lan9303_mdio_read _regmap_read regmap_read lan9303_probe lan9303_mdio_probe mdio_probe really_probe __driver_probe_device driver_probe_device __device_attach_driver bus_for_each_drv __device_attach device_initial_probe bus_probe_device deferred_probe_work_func process_one_work worker_thread kthread ret_from_fork -> #0 (lan9303_mdio:131:(&lan9303_mdio_regmap_config)->lock){+.+.}-{3:3}: __lock_acquire lock_acquire.part.0 lock_acquire __mutex_lock mutex_lock_nested regmap_lock_mutex regmap_read lan9303_phy_read dsa_slave_phy_read __mdiobus_read mdiobus_read get_phy_device mdiobus_scan __mdiobus_register dsa_register_switch lan9303_probe lan9303_mdio_probe mdio_probe really_probe __driver_probe_device driver_probe_device __device_attach_driver bus_for_each_drv __device_attach device_initial_probe bus_probe_device deferred_probe_work_func process_one_work worker_thread kthread ret_from_fork other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&bus->mdio_lock); lock(lan9303_mdio:131:(&lan9303_mdio_regmap_config)->lock); lock(&bus->mdio_lock); lock(lan9303_mdio:131:(&lan9303_mdio_regmap_config)->lock); *** DEADLOCK *** 5 locks held by kworker/u4:3/609: #0: ffff000002842938 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work #1: ffff80000bacbd60 (deferred_probe_work){+.+.}-{0:0}, at: process_one_work #2: ffff000007645178 (&dev->mutex){....}-{3:3}, at: __device_attach #3: ffff8000096e6e78 (dsa2_mutex){+.+.}-{3:3}, at: dsa_register_switch #4: ffff0000114c44d8 (&bus->mdio_lock){+.+.}-{3:3}, at: mdiobus_read stack backtrace: CPU: 1 PID: 609 Comm: kworker/u4:3 Not tainted 5.15.71 #1 Workqueue: events_unbound deferred_probe_work_func Call trace: dump_backtrace show_stack dump_stack_lvl dump_stack print_circular_bug check_noncircular __lock_acquire lock_acquire.part.0 lock_acquire __mutex_lock mutex_lock_nested regmap_lock_mutex regmap_read lan9303_phy_read dsa_slave_phy_read __mdiobus_read mdiobus_read get_phy_device mdiobus_scan __mdiobus_register dsa_register_switch lan9303_probe lan9303_mdio_probe ... Cc: stable@vger.kernel.org Fixes: dc70058315 ("net: dsa: LAN9303: add MDIO managed mode support") Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Link: https://lore.kernel.org/r/20231027065741.534971-1-alexander.sverdlin@siemens.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>		2023-11-02 10:48:09 +01:00
..
b53	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
hirschmann	net: dsa: hirschmann: Convert to platform remove callback returning void	2023-09-20 10:25:57 +01:00
microchip	net: dsa: microchip: ksz9477: Fix spelling mistake "Enery" -> "Energy"	2023-10-27 14:45:50 -07:00
mv88e6xxx	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
ocelot	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
qca	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
realtek	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
sja1105	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
xrs700x	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
bcm_sf2.c	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
bcm_sf2.h	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
bcm_sf2_cfp.c	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
bcm_sf2_regs.h	net: dsa: bcm_sf2: refactor LED regs access	2021-12-30 17:28:32 -08:00
dsa_loop.c	net: dsa: dsa_loop: add phylink capabilities	2023-10-11 10:06:05 +01:00
dsa_loop.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
dsa_loop_bdinfo.c	treewide: Add SPDX license identifier for more missed files	2019-05-21 10:50:45 +02:00
Kconfig	net: dsa: mt7530: improve and relax PHY driver dependency	2023-08-09 11:22:55 +01:00
lan9303-core.c	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
lan9303.h	net: dsa: be compatible with masters which unregister on shutdown	2021-09-19 12:08:37 +01:00
lan9303_i2c.c	net: dsa: Switch i2c drivers back to use .probe()	2023-05-31 09:52:55 +01:00
lan9303_mdio.c	net: dsa: lan9303: consequently nested-lock physical MDIO	2023-11-02 10:48:09 +01:00
lantiq_gswip.c	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
lantiq_pce.h	net: dsa: Use the correct style for SPDX License Identifier	2019-09-22 15:25:08 -07:00
Makefile	net: dsa: mt7530: introduce driver for MT7988 built-in switch	2023-04-03 10:13:01 +01:00
mt7530-mdio.c	net: dsa: mt7530: fix support for MT7531BE	2023-04-19 17:37:45 -07:00
mt7530-mmio.c	net: dsa: mt7530: Convert to platform remove callback returning void	2023-09-20 10:25:57 +01:00
mt7530.c	net: dsa: Use conduit and user terms	2023-10-24 13:08:14 -07:00
mt7530.h	net: dsa: mt7530: fix handling of 802.1X PAE frames	2023-08-19 12:29:33 +01:00
mv88e6060.c	net: dsa: mv88e6060: add phylink_get_caps implementation	2023-08-14 18:57:17 -07:00
mv88e6060.h	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152	2019-05-30 11:26:32 -07:00
rzn1_a5psw.c	net: dsa: rzn1_a5psw: Convert to platform remove callback returning void	2023-09-20 10:25:58 +01:00
rzn1_a5psw.h	net: dsa: rzn1-a5psw: add vlan support	2023-08-11 11:58:36 +01:00
vitesse-vsc73xx-core.c	net: dsa: vsc73xx: replace deprecated strncpy with ethtool_sprintf	2023-10-13 16:28:35 -07:00
vitesse-vsc73xx-platform.c	net: dsa: vitesse-vsc73xx: Convert to platform remove callback returning void	2023-09-20 10:25:58 +01:00
vitesse-vsc73xx-spi.c	net: dsa: vitesse-vsc73xx: remove unnecessary set_drvdata()	2022-09-22 19:30:39 -07:00
vitesse-vsc73xx.h	net: dsa: vsc73xxx: Make vsc73xx_remove() return void	2021-11-15 13:15:07 +00:00