Re: [PATCH] ACPICA: Tables: Remove a hidden logic related to acpi_tb_install_standard_table()

On Thu, Jan 19, 2017 at 10:38 AM, Tomi Sarvela [off-list ref] wrote:

On Thursday, 19 January 2017 15:21:34 EET Lv Zheng wrote:

quoted

There is a hidden logic for acpi_tb_install_standard_table() as it
can be invoked from boot stage and during runtime.
1. When it is invoked from the OS boot stage, ACPICA mutex may not
be available, and thus no
acpi_ut_acquire_mutex()/acpi_ut_release_mutex() are invoked in
these code paths:
   acpi_initialize_tables
     acpi_tb_parse_root_table
       acpi_tb_install_standard_table (4 invocations)
   acpi_install_table
       acpi_tb_install_standard_table
2. When it is invoked during the runtime, ACPICA mutex is correctly
used: acpi_ex_load_op
     acpi_tb_install_and_load_table
       acpi_tb_install_standard_table
   acpi_load_table
     acpi_tb_install_and_load_table
       acpi_tb_install_standard_table
So the mutex is now used in acpi_tb_install_and_load_table(), while
it actually should be in acpi_tb_install_standard_table().

This introduces another problem in acpi_tb_install_standard_table()
where acpi_gbl_table_handler is invoked from and the lock contexts
are thus not consistent for the table handlers. This triggers a
regression when acpi_get_table()/acpi_put_table() start to hold
table mutex during runtime.

The regression is noticed by LKP as new errors reported by ACPICA
mutex debugging facility.
[    2.043693] ACPI Error: Mutex [ACPI_MTX_Tables] already acquired
by this thread [497483776] (20160930/utmutex-254) [    2.054084]
ACPI Error: Mutex [0x2] is not acquired, cannot release
(20160930/utmutex-326)

And it triggers a dead lock:
[  247.066214] INFO: task swapper/0:1 blocked for more than 120
seconds. ...
[  247.091271] Call Trace:
...
[  247.121523]  down_timeout+0x47/0x50
[  247.125065]  acpi_os_wait_semaphore+0x47/0x62
[  247.129475]  acpi_ut_acquire_mutex+0x43/0x81
[  247.133798]  acpi_get_table+0x2d/0x84
[  247.137513]  acpi_table_attr_init+0xcd/0x100
[  247.146590]  acpi_sysfs_table_handler+0x5d/0xb8
[  247.151174]  acpi_bus_table_handler+0x23/0x2a
[  247.155583]  acpi_tb_install_standard_table+0xe0/0x213
[  247.164489]  acpi_tb_install_and_load_table+0x3a/0x82
[  247.169592]  acpi_ex_load_op+0x194/0x201
...
[  247.200108]  acpi_ns_evaluate+0x1bb/0x247
[  247.204170]  acpi_evaluate_object+0x178/0x274
[  247.213249]  acpi_processor_set_pdc+0x154/0x17b
...
The table mutex is held in acpi_tb_install_and_load_table() and is
re-visited by acpi_get_table().

Noticing that the early mutex requirement actually belongs to the
OSL layer and has already been handled in Linux
acpi_os_wait_semaphore()/acpi_os_signal_semaphore(). This patch then
can fix the regression by removing this hidden logic from ACPICA
core and leaving it to OSPMs. A documentation update should also be
required.

Fixes: 174cc7187e6f ('ACPICA: Tables: Back port
acpi_get_table_with_size() and early_acpi_os_unmap_memory() from
Linux kernel') Reported-by: Tomi Sarvela [off-list ref]
Reported-by: Ye Xiaolong <redacted>
Cc: Tomi Sarvela <redacted>
Cc: Ye Xiaolong <redacted>
Signed-off-by: Lv Zheng <redacted>
---

This patch helps ILK-650 testhost survive past the boot ACPI setup.

Tested-by: Tomi Sarvela <redacted>

OK

I'm queuing this up as a fix for 4.10.

Thanks,
Rafael