Re: [PATCH v3] i2c: lpi2c: cache peripheral clock rate
From: Sverdlin, Alexander
Date: Mon May 15 2023 - 08:05:34 EST
Hello Alexander!
On Mon, 2023-05-15 at 11:11 +0200, Alexander Stein wrote:
> > [ 22.503179] other info that might help us debug this:
> > [ 22.503179]
> > [ 22.503183] Chain exists of:
> > [ 22.503183] prepare_lock --> rtc_pcf85063:594:(&config-
> > >regmap)->lock
> > --> i2c_register_adapter
> > [ 22.503183]
> > [ 22.503207] Possible unsafe locking scenario:
> > [ 22.503207]
> > [ 22.503210] CPU0 CPU1
> > [ 22.503213] ---- ----
> > [ 22.503216] lock(i2c_register_adapter);
> > [ 22.503225]
> > lock(rtc_pcf85063:594:(&config-
> > > regmap)->lock);
> >
> > [ 22.503235]
> > lock(i2c_register_adapter);
> > [ 22.503244] lock(prepare_lock);
> > [ 22.503253]
> > [ 22.503253] *** DEADLOCK ***
> >
> > Now lpi2c_runtime_resume will call into clk_prepare() which also
> > calls
> > clk_prepare_lock() (identical to clk_get_rate).
> >
> > Best regards,
> > Alexader
> >
> > > pm_runtime_set_autosuspend_delay(&pdev->dev,
> > > I2C_PM_TIMEOUT);
> > > pm_runtime_use_autosuspend(&pdev->dev);
> > > pm_runtime_get_noresume(&pdev->dev);
>
> With commit fa39065833db ("i2c: imx-lpi2c: avoid taking clk_prepare
> mutex in
> PM callbacks") in place, the additional deadlock warning regarding
> runtime
> resume is gone.
> So only the ordering issue needs to be addressed.
Unfortunately with both your (backported) and my patches applied I've
got a 3rd warning:
======================================================
WARNING: possible circular locking dependency detected
5.15.71+git8e43aee #1 Tainted: G O
------------------------------------------------------
xxxxxxx/2238 is trying to acquire lock:
ffff0000040bda40 (&desc->request_mutex){+.+.}-{3:3}, at:
__setup_irq+0xbc/0x8bc
but task is already holding lock:
ffff000010ef1100 (i2c_register_adapter){+.+.}-{3:3}, at:
i2c_adapter_lock_bus+0x2c/0x3c
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #5 (i2c_register_adapter){+.+.}-{3:3}:
lock_acquire+0x68/0x84
rt_mutex_lock_nested+0x88/0xe0
i2c_adapter_lock_bus+0x2c/0x3c
i2c_transfer+0x58/0x130
regmap_i2c_read+0x64/0xb0
_regmap_raw_read+0x114/0x440
_regmap_bus_read+0x4c/0x84
_regmap_read+0x6c/0x270
regmap_read+0x54/0x80
pcf85063_probe+0xec/0x4cc
i2c_device_probe+0x10c/0x350
really_probe+0xc4/0x470
__driver_probe_device+0x11c/0x190
driver_probe_device+0x48/0x110
__device_attach_driver+0xc4/0x160
bus_for_each_drv+0x80/0xe0
__device_attach+0xb0/0x1f0
device_initial_probe+0x1c/0x2c
bus_probe_device+0xa4/0xb0
device_add+0x398/0x8ac
device_register+0x28/0x40
i2c_new_client_device+0x144/0x290
of_i2c_register_devices+0x18c/0x230
i2c_register_adapter+0x1dc/0x6b0
__i2c_add_numbered_adapter+0x68/0xbc
i2c_add_adapter+0xb0/0xe0
lpi2c_imx_probe+0x3a4/0x670
platform_probe+0x70/0xec
really_probe+0xc4/0x470
__driver_probe_device+0x11c/0x190
driver_probe_device+0x48/0x110
__device_attach_driver+0xc4/0x160
bus_for_each_drv+0x80/0xe0
__device_attach+0xb0/0x1f0
device_initial_probe+0x1c/0x2c
bus_probe_device+0xa4/0xb0
deferred_probe_work_func+0xb8/0x110
process_one_work+0x27c/0x6c4
worker_thread+0x7c/0x450
kthread+0x168/0x17c
ret_from_fork+0x10/0x20
-> #4 (rtc_pcf85063:560:(&config->regmap)->lock){+.+.}-{3:3}:
lock_acquire+0x68/0x84
__mutex_lock+0xa8/0x4d0
mutex_lock_nested+0x48/0x54
regmap_lock_mutex+0x1c/0x30
regmap_read+0x44/0x80
pcf85063_clkout_recalc_rate+0x34/0x80
__clk_register+0x520/0x880
devm_clk_register+0x64/0xc4
pcf85063_probe+0x24c/0x4cc
i2c_device_probe+0x10c/0x350
really_probe+0xc4/0x470
__driver_probe_device+0x11c/0x190
driver_probe_device+0x48/0x110
__device_attach_driver+0xc4/0x160
bus_for_each_drv+0x80/0xe0
__device_attach+0xb0/0x1f0
device_initial_probe+0x1c/0x2c
bus_probe_device+0xa4/0xb0
device_add+0x398/0x8ac
device_register+0x28/0x40
i2c_new_client_device+0x144/0x290
of_i2c_register_devices+0x18c/0x230
i2c_register_adapter+0x1dc/0x6b0
__i2c_add_numbered_adapter+0x68/0xbc
i2c_add_adapter+0xb0/0xe0
lpi2c_imx_probe+0x3a4/0x670
platform_probe+0x70/0xec
really_probe+0xc4/0x470
__driver_probe_device+0x11c/0x190
driver_probe_device+0x48/0x110
__device_attach_driver+0xc4/0x160
bus_for_each_drv+0x80/0xe0
__device_attach+0xb0/0x1f0
device_initial_probe+0x1c/0x2c
bus_probe_device+0xa4/0xb0
deferred_probe_work_func+0xb8/0x110
process_one_work+0x27c/0x6c4
worker_thread+0x7c/0x450
kthread+0x168/0x17c
ret_from_fork+0x10/0x20
-> #3 (prepare_lock){+.+.}-{3:3}:
lock_acquire+0x68/0x84
__mutex_lock+0xa8/0x4d0
mutex_lock_nested+0x48/0x54
clk_prepare_lock+0x50/0xb0
clk_prepare+0x28/0x50
fec_runtime_resume+0x3c/0xe0
pm_generic_runtime_resume+0x34/0x50
__genpd_runtime_resume+0x38/0x90
genpd_runtime_resume+0xa0/0x304
__rpm_callback+0x50/0x1b0
rpm_callback+0x40/0x80
rpm_resume+0x448/0x6e0
__pm_runtime_resume+0x50/0xc0
fec_enet_mdio_read+0x48/0x190
__mdiobus_read+0x48/0xb0
mdiobus_read_nested+0x48/0x70
mv88e6xxx_smi_dual_direct_read+0x2c/0x50
mv88e6xxx_read+0x64/0xf0
mv88e6xxx_g1_read+0x28/0x34
mv88e6xxx_g1_irq_thread_work+0x50/0x17c
mv88e6xxx_irq_poll+0x28/0x50
kthread_worker_fn+0x100/0x480
kthread+0x168/0x17c
ret_from_fork+0x10/0x20
-> #2 (&bus->mdio_lock/2){+.+.}-{3:3}:
lock_acquire+0x68/0x84
__mutex_lock+0xa8/0x4d0
mutex_lock_nested+0x48/0x54
mdiobus_read_nested+0x38/0x70
mv88e6xxx_smi_dual_direct_read+0x2c/0x50
mv88e6xxx_read+0x64/0xf0
mv88e6xxx_port_read+0x24/0x30
mv88e6xxx_probe+0x250/0x7f0
mdio_probe+0x3c/0x80
really_probe+0xc4/0x470
__driver_probe_device+0x11c/0x190
driver_probe_device+0x48/0x110
__device_attach_driver+0xc4/0x160
bus_for_each_drv+0x80/0xe0
__device_attach+0xb0/0x1f0
device_initial_probe+0x1c/0x2c
bus_probe_device+0xa4/0xb0
deferred_probe_work_func+0xb8/0x110
process_one_work+0x27c/0x6c4
worker_thread+0x7c/0x450
kthread+0x168/0x17c
ret_from_fork+0x10/0x20
-> #1 (&chip->reg_lock){+.+.}-{3:3}:
lock_acquire+0x68/0x84
__mutex_lock+0xa8/0x4d0
mutex_lock_nested+0x48/0x54
mv88e6xxx_g1_irq_bus_lock+0x24/0x30
__setup_irq+0x6e0/0x8bc
request_threaded_irq+0xf4/0x1b4
mv88e6xxx_g2_irq_setup+0x1f0/0x2b4
mv88e6xxx_probe+0x480/0x7f0
mdio_probe+0x3c/0x80
really_probe+0xc4/0x470
__driver_probe_device+0x11c/0x190
driver_probe_device+0x48/0x110
__device_attach_driver+0xc4/0x160
bus_for_each_drv+0x80/0xe0
__device_attach+0xb0/0x1f0
device_initial_probe+0x1c/0x2c
bus_probe_device+0xa4/0xb0
deferred_probe_work_func+0xb8/0x110
process_one_work+0x27c/0x6c4
worker_thread+0x7c/0x450
kthread+0x168/0x17c
ret_from_fork+0x10/0x20
-> #0 (&desc->request_mutex){+.+.}-{3:3}:
__lock_acquire+0x12a4/0x20a0
lock_acquire.part.0+0xe0/0x230
lock_acquire+0x68/0x84
__mutex_lock+0xa8/0x4d0
mutex_lock_nested+0x48/0x54
__setup_irq+0xbc/0x8bc
request_threaded_irq+0xf4/0x1b4
devm_request_threaded_irq+0x88/0x104
lpi2c_runtime_resume+0x70/0xe4
pm_generic_runtime_resume+0x34/0x50
__genpd_runtime_resume+0x38/0x90
genpd_runtime_resume+0xa0/0x304
__rpm_callback+0x50/0x1b0
rpm_callback+0x74/0x80
rpm_resume+0x448/0x6e0
__pm_runtime_resume+0x50/0xc0
lpi2c_imx_xfer+0x60/0xa5c
__i2c_transfer+0x174/0xa80
i2c_transfer+0x68/0x130
regmap_i2c_read+0x64/0xb0
_regmap_raw_read+0x114/0x440
regmap_raw_read+0x19c/0x28c
regmap_bulk_read+0x1b8/0x244
at24_read+0x14c/0x2c4
nvmem_reg_read+0x2c/0x54
bin_attr_nvmem_read+0x8c/0xbc
sysfs_kf_bin_read+0x74/0x94
kernfs_fop_read_iter+0xb0/0x1d0
new_sync_read+0xf0/0x184
vfs_read+0x154/0x1f0
ksys_read+0x70/0x100
__arm64_sys_read+0x24/0x30
invoke_syscall+0x50/0x120
el0_svc_common.constprop.0+0x68/0x124
do_el0_svc+0x30/0x9c
el0_svc+0x54/0x110
el0t_64_sync_handler+0xa4/0x130
el0t_64_sync+0x1a0/0x1a4
other info that might help us debug this:
Chain exists of:
&desc->request_mutex --> rtc_pcf85063:560:(&config->regmap)->lock -->
i2c_register_adapter
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(i2c_register_adapter);
lock(rtc_pcf85063:560:(&config->regmap)-
>lock);
lock(i2c_register_adapter);
lock(&desc->request_mutex);
*** DEADLOCK ***
4 locks held by xxxxxxx/2238:
#0: ffff000015a64488 (&of->mutex){+.+.}-{3:3}, at:
kernfs_fop_read_iter+0x74/0x1d0
#1: ffff0000119e2400 (kn->active#58){.+.+}-{0:0}, at:
kernfs_fop_read_iter+0x7c/0x1d0
#2: ffff0000119a26e8 (&at24->lock){+.+.}-{3:3}, at:
at24_read+0x8c/0x2c4
#3: ffff000010ef1100 (i2c_register_adapter){+.+.}-{3:3}, at:
i2c_adapter_lock_bus+0x2c/0x3c
stack backtrace:
CPU: 1 PID: 2238 Comm: xxxxxxx Tainted: G O
5.15.71+git8e43aee #1
Hardware name: Siemens PXC5.E24 (DT)
Call trace:
dump_backtrace+0x0/0x1d4
show_stack+0x20/0x2c
dump_stack_lvl+0x8c/0xb8
dump_stack+0x18/0x34
print_circular_bug+0x1f8/0x200
check_noncircular+0x130/0x144
__lock_acquire+0x12a4/0x20a0
lock_acquire.part.0+0xe0/0x230
lock_acquire+0x68/0x84
__mutex_lock+0xa8/0x4d0
mutex_lock_nested+0x48/0x54
__setup_irq+0xbc/0x8bc
request_threaded_irq+0xf4/0x1b4
devm_request_threaded_irq+0x88/0x104
lpi2c_runtime_resume+0x70/0xe4
pm_generic_runtime_resume+0x34/0x50
__genpd_runtime_resume+0x38/0x90
genpd_runtime_resume+0xa0/0x304
__rpm_callback+0x50/0x1b0
rpm_callback+0x74/0x80
rpm_resume+0x448/0x6e0
__pm_runtime_resume+0x50/0xc0
lpi2c_imx_xfer+0x60/0xa5c
__i2c_transfer+0x174/0xa80
i2c_transfer+0x68/0x130
regmap_i2c_read+0x64/0xb0
_regmap_raw_read+0x114/0x440
regmap_raw_read+0x19c/0x28c
regmap_bulk_read+0x1b8/0x244
at24_read+0x14c/0x2c4
nvmem_reg_read+0x2c/0x54
bin_attr_nvmem_read+0x8c/0xbc
sysfs_kf_bin_read+0x74/0x94
kernfs_fop_read_iter+0xb0/0x1d0
new_sync_read+0xf0/0x184
vfs_read+0x154/0x1f0
ksys_read+0x70/0x100
__arm64_sys_read+0x24/0x30
invoke_syscall+0x50/0x120
el0_svc_common.constprop.0+0x68/0x124
do_el0_svc+0x30/0x9c
el0_svc+0x54/0x110
el0t_64_sync_handler+0xa4/0x130
el0t_64_sync+0x1a0/0x1a4
So this doesn't look like an end of the story yet, unfortunately.
--
Alexander Sverdlin
Siemens AG
www.siemens.com