From 7fde14d705985dd933a3d916d39daa72b1668098 Mon Sep 17 00:00:00 2001 From: Tong Zhang Date: Sun, 23 Jan 2022 01:10:04 -0800 Subject: [PATCH] drm/privacy-screen: honor acpi=off in detect_thinkpad_privacy_screen when acpi=off is provided in bootarg, kernel crash with [ 1.252739] BUG: kernel NULL pointer dereference, address: 0000000000000018 [ 1.258308] Call Trace: [ 1.258490] ? acpi_walk_namespace+0x147/0x147 [ 1.258770] acpi_get_devices+0xe4/0x137 [ 1.258921] ? drm_core_init+0xc0/0xc0 [drm] [ 1.259108] detect_thinkpad_privacy_screen+0x5e/0xa8 [drm] [ 1.259337] drm_privacy_screen_lookup_init+0xe/0xe85 [drm] The reason is that acpi_walk_namespace expects acpi related stuff initialized but in fact it wouldn't when acpi is set to off. In this case we should honor acpi=off in detect_thinkpad_privacy_screen(). Signed-off-by: Tong Zhang Reviewed-by: Hans de Goede Signed-off-by: Hans de Goede Link: https://patchwork.freedesktop.org/patch/msgid/20220123091004.763775-1-ztong0001@gmail.com --- drivers/gpu/drm/drm_privacy_screen_x86.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/drm_privacy_screen_x86.c b/drivers/gpu/drm/drm_privacy_screen_x86.c index a2cafb2..e7aa74a 100644 --- a/drivers/gpu/drm/drm_privacy_screen_x86.c +++ b/drivers/gpu/drm/drm_privacy_screen_x86.c @@ -33,6 +33,9 @@ static bool __init detect_thinkpad_privacy_screen(void) unsigned long long output; acpi_status status; + if (acpi_disabled) + return false; + /* Get embedded-controller handle */ status = acpi_get_devices("PNP0C09", acpi_set_handle, NULL, &ec_handle); if (ACPI_FAILURE(status) || !ec_handle) -- 2.7.4