[PATCH 0/3] Get device's parent from parent field, fix sleeping IRQs disabled

Sakari Ailus
2021-11-03T13:33:57Z

Hi all,

This set changes getting fwnode's parent on ACPI fwnode so it no longer
needs a semaphore, using struct acpi_device->parent field instead of
calling acpi_get_parent(). The semaphore is being acquired when the
device's full path is printed which now takes place local IRQs disabled:

--------8<------------------------
BUG: sleeping function called from invalid context at kernel/locking/semaphore.c:163

...

Call Trace:
<TASK>
dump_stack_lvl+0x57/0x7d
__might_resched.cold+0xf4/0x12f
down_timeout+0x21/0x70
acpi_os_wait_semaphore+0x63/0x180
acpi_ut_acquire_mutex+0x123/0x1ba
acpi_get_parent+0x30/0x71
acpi_node_get_parent+0x64/0x90
? lock_acquire+0x1a0/0x300
fwnode_count_parents+0x6d/0xb0
fwnode_full_name_string+0x18/0x90
fwnode_string+0xd7/0x140
vsnprintf+0x1ec/0x4f0
va_format.constprop.0+0x6a/0x130
vsnprintf+0x1ec/0x4f0
vprintk_store+0x271/0x5a0
? rcu_read_lock_sched_held+0x12/0x70
? lock_release+0x228/0x310
? acpi_initialize_hp_context+0x50/0x50
vprintk_emit+0xd5/0x340
_printk+0x58/0x6f
__dynamic_pr_debug+0xe2/0x100
__v4l2_fwnode_endpoint_parse+0x10c/0x450 [v4l2_fwnode]
v4l2_fwnode_endpoint_parse+0x11/0x40 [v4l2_fwnode]
cio2_pci_probe.cold+0x7fb/0x969 [ipu3_cio2]
? _raw_spin_unlock_irqrestore+0x42/0x70
pci_device_probe+0xb6/0x140
really_probe+0x1f5/0x3f0
__driver_probe_device+0xfe/0x180
driver_probe_device+0x1e/0x90
__driver_attach+0xc4/0x1d0
? __device_attach_driver+0xe0/0xe0
? __device_attach_driver+0xe0/0xe0
bus_for_each_dev+0x7b/0xc0
bus_add_driver+0x14c/0x1f0
driver_register+0x8b/0xe0
? 0xffffffffa0428000
do_one_initcall+0x5b/0x300
? rcu_read_lock_sched_held+0x12/0x70
? trace_kmalloc+0x29/0xd0
? kmem_cache_alloc_trace+0x11d/0x630
do_init_module+0x5c/0x260
__do_sys_finit_module+0xae/0x110
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
--------8<------------------------

I guess one could argue it wasn't great to begin with that getting
fwnode's parent required a semaphore to begin with, nevertheless John's
patch made it a concrete problem. Added Cc: stable, too.

Sakari Ailus (3):
ACPI: Make acpi_fwnode_handle safer
ACPI: Get acpi_device's parent from the parent field
ACPI: Make acpi_node_get_parent() local

drivers/acpi/property.c | 15 ++++++---------
include/acpi/acpi_bus.h | 2 +-
include/linux/acpi.h | 7 -------
3 files changed, 7 insertions(+), 17 deletions(-)

--
2.30.2