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

[Sakari Ailus <sakari.ailus@linux.intel.com>]

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