There is a lock order issue in acpi_load_tables(). The namespace lock
is held before holding the interpreter lock.
With ACPI_MUTEX_DEBUG enabled in the kernel, this is printed to the
log during boot:
[ 0.885699] ACPI Error: Invalid acquire order: Thread 405884224 owns [ACPI_MTX_Namespace], wants [ACPI_MTX_Interpreter] (20160422/utmutex-263)
[ 0.885881] ACPI Error: Could not acquire AML Interpreter mutex (20160422/exutils-95)
[ 0.893846] ACPI Error: Mutex [0x0] is not acquired, cannot release (20160422/utmutex-326)
[ 0.894019] ACPI Error: Could not release AML Interpreter mutex (20160422/exutils-133)
The issue has been introduced by the following commit:
Commit: 2f38b1b16d
ACPICA Commit: bfe03ffcde8ed56a7eae38ea0b188aeb12f9c52e
Subject: ACPICA: Namespace: Fix a regression that MLC support triggers
dead lock in dynamic table loading
Which fixed a deadlock issue for acpi_ns_load_table() in
acpi_ex_add_table() but didn't take care of the lock order in
acpi_ns_load_table() correctly.
Originally (before the above commit), ACPICA used the
namespace/interpreter locks in the following 2 key code
paths:
1. Table loading:
acpi_ns_load_table
L(Namespace)
acpi_ns_parse_table
acpi_ns_one_complete_parse
U(Namespace)
2. Object evaluation:
acpi_ns_evaluate
L(Interpreter)
acpi_ps_execute_method
U(Interpreter)
acpi_ns_load_table
L(Namespace)
U(Namespace)
acpi_ev_initialize_region
L(Namespace)
U(Namespace)
address_space.setup
L(Namespace)
U(Namespace)
address_space.handler
L(Namespace)
U(Namespace)
acpi_os_wait_semaphore
acpi_os_acquire_mutex
acpi_os_sleep
L(Interpreter)
U(Interpreter)
During runtime, while acpi_ns_evaluate is called, the lock order is
always Interpreter -> Namespace.
In turn, the problematic commit acquires the locks in the following
order:
3. Table loading:
acpi_ns_load_table
L(Namespace)
acpi_ns_parse_table
L(Interpreter)
acpi_ns_one_complete_parse
U(Interpreter)
U(Namespace)
To fix the lock order issue, move the interpreter lock to
acpi_ns_load_table() to ensure the lock order correctness:
4. Table loading:
acpi_ns_load_table
L(Interpreter)
L(Namespace)
acpi_ns_parse_table
acpi_ns_one_complete_parse
U(Namespace)
U(Interpreter)
However, this doesn't fix the current design issues related to the
namespace lock. For example, we can notice that in acpi_ns_evaluate(),
outside of acpi_ns_load_table(), the namespace objects may be created
by the named object creation control methods. And the creation of
the method-owned namespace objects are not locked by the namespace
lock. This patch doesn't try to fix such kind of existing issues.
Fixes: 2f38b1b16d (ACPICA: Namespace: Fix a regression that MLC support triggers dead lock in dynamic table loading)
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
45209046c4