On Mon, Oct 12, 2020 at 3:05 PM Jamie Iles <jamie@xxxxxxxxxxxx> wrote:
>
> 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);
> --
Applied as 5.10-rc material, thanks!
