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@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Signed-off-by: Jamie Iles <jamie@xxxxxxxxxxxx>
---
drivers/acpi/acpi_dbg.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/acpi/acpi_dbg.c b/drivers/acpi/acpi_dbg.c
index 6041974c7627..fb7290338593 100644
--- 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);
--
2.25.1
