The execution of each control method is protected by a mutex.
acpi_ds_begin_method_execution avoids trying to reacquire a mutex during
recursion by checking if the mutex is already held by the current
thread. The mutex's thread_id is only set in
acpi_ds_begin_method_execution if a walk state is present (when the
method is being called by another method). This fails for the external
entry point method executed via acpi_ps_execute_method: the mutex is
acquired but as walk_state is null the thread_id is not set. Subsequent
recursion on the entry method then blocks indefinitely attempting to
grab the mutex that the thread already holds. Fix by initializing the
mutex's thread_id with acpi_os_get_thread_id when a walk state is not
available.
For me this bug is triggered by thunderbolt hotplug on a Dell XPS 15
9550, breaking hotplug and causing subsequent suspend or shutdown to
hang indefinitely.
INFO: task kworker/0:1:60 blocked for more than 120 seconds.
Not tainted 4.4.0-4-generic #19
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this
message.
kworker/0:1 D ffff8804a9f13a48 0 60 2 0x00000000
Workqueue: kacpid acpi_os_execute_deferred
ffff8804a9f13a48 000000000000002f 0000000000000000 ffffffff81e11540
ffff8804a9ea9b40 ffff8804a9f14000 ffff880378947600 ffff8804a9ea9b40
ffff8804ac4e26b8 ffff8804ac4e26b8 ffff8804a9f13a60 ffffffff818c38c5
Call Trace:
[<ffffffff818c38c5>] schedule+0x35/0x80
[<ffffffff818c842e>] schedule_timeout+0x22e/0x2f0
[<ffffffff810214f9>] ? sched_clock+0x9/0x10
[<ffffffff810b97ac>] ? local_clock+0x1c/0x20
[<ffffffff810da359>] ? mark_held_locks+0x79/0xa0
[<ffffffff818c941c>] ? _raw_spin_unlock_irq+0x2c/0x40
[<ffffffff810da4a9>] ? trace_hardirqs_on_caller+0x129/0x1b0
[<ffffffff818c7304>] __down_timeout+0x74/0xd0
[<ffffffff810d4169>] ? down_timeout+0x19/0x60
[<ffffffff810d419c>] down_timeout+0x4c/0x60
[<ffffffff814c646c>] acpi_os_wait_semaphore+0xaa/0x16c
[<ffffffff814f37b9>] acpi_ex_system_wait_mutex+0x81/0xfa
[<ffffffff814daefc>] acpi_ds_begin_method_execution+0x25e/0x378
[<ffffffff814db460>] acpi_ds_call_control_method+0x107/0x2de
[<ffffffff8150112f>] acpi_ps_parse_aml+0x17e/0x493
[<ffffffff81501e14>] acpi_ps_execute_method+0x1fa/0x2ba
[<ffffffff814f90fa>] acpi_ns_evaluate+0x2e6/0x42d
[<ffffffff814e203b>] acpi_ev_asynch_execute_gpe_method+0xbd/0x159
[<ffffffff814c55b0>] acpi_os_execute_deferred+0x14/0x20
[<ffffffff8109f93e>] process_one_work+0x1ee/0x570
[<ffffffff8109f8d2>] ? process_one_work+0x182/0x570
[<ffffffff8109fd08>] worker_thread+0x48/0x4a0
[<ffffffff8109fcc0>] ? process_one_work+0x570/0x570
[<ffffffff810a6456>] kthread+0xf6/0x110
[<ffffffff810da4a9>] ? trace_hardirqs_on_caller+0x129/0x1b0
[<ffffffff810a6360>] ? kthread_create_on_node+0x290/0x290
[<ffffffff818ca16f>] ret_from_fork+0x3f/0x70
[<ffffffff810a6360>] ? kthread_create_on_node+0x290/0x290
And part of the impacted method from the DSDT:
Method (_E42, 0, NotSerialized) // _Exx: Edge-Triggered GPE
{
(...)
ADBG ("TBT-HP-Handler")
ADBG ("PEG WorkAround")
PGWA ()
Acquire (OSUM, 0xFFFF)
Local1 = TBFF ()
If ((Local1 == One))
{
Sleep (0x10)
Release (OSUM)
ADBG ("OS_Up_Received")
If (((DPTF == One) && (DDDR == One)))
{
If (((OSYS == 0x07DD) && (_REV == 0x05)))
{
Return (Zero)
}
_E42 ()
}
Return (Zero)
}
(...)
}
Signed-off-by: Andy Clayton <clayt055@xxxxxxx>
---
drivers/acpi/acpica/dsmethod.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/acpi/acpica/dsmethod.c b/drivers/acpi/acpica/dsmethod.c
index 6a72047..c3a052d 100644
--- a/drivers/acpi/acpica/dsmethod.c
+++ b/drivers/acpi/acpica/dsmethod.c
@@ -428,6 +428,9 @@ acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
obj_desc->method.mutex->mutex.
original_sync_level =
obj_desc->method.mutex->mutex.sync_level;
+
+ obj_desc->method.mutex->mutex.thread_id =
+ acpi_os_get_thread_id();
}
}
--
2.7.0
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