From: Jamie Iles jamie@nuviainc.com
commit 0fada277147ffc6d694aa32162f51198d4f10d94 upstream.
If ACPI is disabled then loading the acpi_dbg module will result in the following splat when lock debugging is enabled.
DEBUG_LOCKS_WARN_ON(lock->magic != lock) WARNING: CPU: 0 PID: 1 at kernel/locking/mutex.c:938 __mutex_lock+0xa10/0x1290 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc8+ #103 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x4d8 show_stack+0x34/0x48 dump_stack+0x174/0x1f8 panic+0x360/0x7a0 __warn+0x244/0x2ec report_bug+0x240/0x398 bug_handler+0x50/0xc0 call_break_hook+0x160/0x1d8 brk_handler+0x30/0xc0 do_debug_exception+0x184/0x340 el1_dbg+0x48/0xb0 el1_sync_handler+0x170/0x1c8 el1_sync+0x80/0x100 __mutex_lock+0xa10/0x1290 mutex_lock_nested+0x6c/0xc0 acpi_register_debugger+0x40/0x88 acpi_aml_init+0xc4/0x114 do_one_initcall+0x24c/0xb10 kernel_init_freeable+0x690/0x728 kernel_init+0x20/0x1e8 ret_from_fork+0x10/0x18
This is because acpi_debugger.lock has not been initialized as acpi_debugger_init() is not called when ACPI is disabled. Fail module loading to avoid this and any subsequent problems that might arise by trying to debug AML when ACPI is disabled.
Fixes: 8cfb0cdf07e2 ("ACPI / debugger: Add IO interface to access debugger functionalities") Reviewed-by: Hanjun Guo guohanjun@huawei.com Signed-off-by: Jamie Iles jamie@nuviainc.com Cc: 4.10+ stable@vger.kernel.org # 4.10+ Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/acpi/acpi_dbg.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/acpi/acpi_dbg.c +++ b/drivers/acpi/acpi_dbg.c @@ -749,6 +749,9 @@ static int __init acpi_aml_init(void) { int ret;
+ if (acpi_disabled) + return -ENODEV; + /* Initialize AML IO interface */ mutex_init(&acpi_aml_io.lock); init_waitqueue_head(&acpi_aml_io.wait);