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
