ACPICA: Namespace: Fix namespace/interpreter lock ordering
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: 2f38b1b1 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: 2f38b1b1 (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>
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