7a49f21930
Rework MDIO locking to avoid potential circular locking:
WARNING: possible circular locking dependency detected
5.19.0-rc1-ar9331-00017-g3ab364c7c48c #5 Not tainted
------------------------------------------------------
kworker/u2:4/68 is trying to acquire lock:
81f3c83c (ar9331:1005:(&ar9331_mdio_regmap_config)->lock){+.+.}-{4:4}, at: regmap_write+0x50/0x8c
but task is already holding lock:
81f60494 (&bus->mdio_lock){+.+.}-{4:4}, at: mdiobus_read+0x40/0x78
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&bus->mdio_lock){+.+.}-{4:4}:
lock_acquire+0x2d4/0x360
__mutex_lock+0xf8/0x384
mutex_lock_nested+0x2c/0x38
mdiobus_write+0x44/0x80
ar9331_sw_bus_write+0x50/0xe4
_regmap_raw_write_impl+0x604/0x724
_regmap_bus_raw_write+0x9c/0xb4
_regmap_write+0xdc/0x1a0
_regmap_update_bits+0xf4/0x118
_regmap_select_page+0x108/0x138
_regmap_raw_read+0x25c/0x288
_regmap_bus_read+0x60/0x98
_regmap_read+0xd4/0x1b0
_regmap_update_bits+0xc4/0x118
regmap_update_bits_base+0x64/0x8c
ar9331_sw_irq_bus_sync_unlock+0x40/0x6c
__irq_set_handler+0x7c/0xac
ar9331_sw_irq_map+0x48/0x7c
irq_domain_associate+0x174/0x208
irq_create_mapping_affinity+0x1a8/0x230
ar9331_sw_probe+0x22c/0x388
mdio_probe+0x44/0x70
really_probe+0x200/0x424
__driver_probe_device+0x290/0x298
driver_probe_device+0x54/0xe4
__device_attach_driver+0xe4/0x130
bus_for_each_drv+0xb4/0xd8
__device_attach+0x104/0x1a4
bus_probe_device+0x48/0xc4
device_add+0x600/0x800
mdio_device_register+0x68/0xa0
of_mdiobus_register+0x2bc/0x3c4
ag71xx_probe+0x6e4/0x984
platform_probe+0x78/0xd0
really_probe+0x200/0x424
__driver_probe_device+0x290/0x298
driver_probe_device+0x54/0xe4
__driver_attach+0x17c/0x190
bus_for_each_dev+0x8c/0xd0
bus_add_driver+0x110/0x228
driver_register+0xe4/0x12c
do_one_initcall+0x104/0x2a0
kernel_init_freeable+0x250/0x288
kernel_init+0x34/0x130
ret_from_kernel_thread+0x14/0x1c
-> #0 (ar9331:1005:(&ar9331_mdio_regmap_config)->lock){+.+.}-{4:4}:
check_noncircular+0x88/0xc0
__lock_acquire+0x10bc/0x18bc
lock_acquire+0x2d4/0x360
__mutex_lock+0xf8/0x384
mutex_lock_nested+0x2c/0x38
regmap_write+0x50/0x8c
ar9331_sw_mbus_read+0x74/0x1b8
__mdiobus_read+0x90/0xec
mdiobus_read+0x50/0x78
get_phy_device+0xa0/0x18c
fwnode_mdiobus_register_phy+0x120/0x1d4
of_mdiobus_register+0x244/0x3c4
devm_of_mdiobus_register+0xe8/0x100
ar9331_sw_setup+0x16c/0x3a0
dsa_register_switch+0x7dc/0xcc0
ar9331_sw_probe+0x370/0x388
mdio_probe+0x44/0x70
really_probe+0x200/0x424
__driver_probe_device+0x290/0x298
driver_probe_device+0x54/0xe4
__device_attach_driver+0xe4/0x130
bus_for_each_drv+0xb4/0xd8
__device_attach+0x104/0x1a4
bus_probe_device+0x48/0xc4
deferred_probe_work_func+0xf0/0x10c
process_one_work+0x314/0x4d4
worker_thread+0x2a4/0x354
kthread+0x134/0x13c
ret_from_kernel_thread+0x14/0x1c
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&bus->mdio_lock);
lock(ar9331:1005:(&ar9331_mdio_regmap_config)->lock);
lock(&bus->mdio_lock);
lock(ar9331:1005:(&ar9331_mdio_regmap_config)->lock);
*** DEADLOCK ***
5 locks held by kworker/u2:4/68:
#0: 81c04eb4 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1e4/0x4d4
#1: 81f0de78 (deferred_probe_work){+.+.}-{0:0}, at: process_one_work+0x1e4/0x4d4
#2:
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.