From 1654e53349d4e657b331de354313461f401f5063 Mon Sep 17 00:00:00 2001 From: Sangyun Kim Date: Mon, 20 Apr 2026 14:13:18 +0900 Subject: [PATCH] HID: appletb-kbd: run inactivity autodim from workqueues The autodim code in hid-appletb-kbd takes backlight_device->ops_lock via backlight_device_set_brightness() -> mutex_lock() from two different atomic contexts: * appletb_inactivity_timer() is a struct timer_list callback, so it runs in softirq context. Every expiry triggers BUG: sleeping function called from invalid context at kernel/locking/mutex.c:591 Call Trace: __might_resched __mutex_lock backlight_device_set_brightness appletb_inactivity_timer call_timer_fn run_timer_softirq * reset_inactivity_timer() is called from appletb_kbd_hid_event() and appletb_kbd_inp_event(). On real USB hardware these run in softirq/IRQ context (URB completion and input-event dispatch). When the Touch Bar has already been dimmed or turned off, the reset path calls backlight_device_set_brightness() directly to restore brightness, producing the same warning. Both call sites hit the same mutex_lock()-from-atomic bug. Fix them together by moving the blocking work onto the system workqueue: * Convert the inactivity timer from struct timer_list to struct delayed_work; the callback (appletb_inactivity_work) now runs in process context where mutex_lock() is legal. * Add a dedicated struct work_struct restore_brightness_work and have reset_inactivity_timer() schedule it instead of calling backlight_device_set_brightness() directly. Cancel both works synchronously during driver tear-down alongside the existing backlight reference drop. The semantics are unchanged (same delays, same state transitions on dim, turn-off and user activity); only the execution context of the sleeping call changes. The timer field and callback are renamed to match their new type; reset_inactivity_timer() keeps its name because it is invoked from input event paths that read naturally as "reset the inactivity timer". Fixes: 93a0fc489481 ("HID: hid-appletb-kbd: add support for automatic brightness control while using the touchbar") Cc: stable@vger.kernel.org Signed-off-by: Sangyun Kim Signed-off-by: Jiri Kosina --- drivers/hid/hid-appletb-kbd.c | 44 ++++++++++++++++++++++++----------- 1 file changed, 30 insertions(+), 14 deletions(-) diff --git a/drivers/hid/hid-appletb-kbd.c b/drivers/hid/hid-appletb-kbd.c index 8feac9e3589b..462010a75899 100644 --- a/drivers/hid/hid-appletb-kbd.c +++ b/drivers/hid/hid-appletb-kbd.c @@ -17,7 +17,7 @@ #include #include #include -#include +#include #include #include "hid-ids.h" @@ -62,7 +62,8 @@ struct appletb_kbd { struct input_handle kbd_handle; struct input_handle tpd_handle; struct backlight_device *backlight_dev; - struct timer_list inactivity_timer; + struct delayed_work inactivity_work; + struct work_struct restore_brightness_work; bool has_dimmed; bool has_turned_off; u8 saved_mode; @@ -164,16 +165,18 @@ static int appletb_tb_key_to_slot(unsigned int code) } } -static void appletb_inactivity_timer(struct timer_list *t) +static void appletb_inactivity_work(struct work_struct *work) { - struct appletb_kbd *kbd = timer_container_of(kbd, t, inactivity_timer); + struct appletb_kbd *kbd = container_of(to_delayed_work(work), + struct appletb_kbd, + inactivity_work); if (kbd->backlight_dev && appletb_tb_autodim) { if (!kbd->has_dimmed) { backlight_device_set_brightness(kbd->backlight_dev, 1); kbd->has_dimmed = true; - mod_timer(&kbd->inactivity_timer, - jiffies + secs_to_jiffies(appletb_tb_idle_timeout)); + mod_delayed_work(system_wq, &kbd->inactivity_work, + secs_to_jiffies(appletb_tb_idle_timeout)); } else if (!kbd->has_turned_off) { backlight_device_set_brightness(kbd->backlight_dev, 0); kbd->has_turned_off = true; @@ -181,16 +184,25 @@ static void appletb_inactivity_timer(struct timer_list *t) } } +static void appletb_restore_brightness_work(struct work_struct *work) +{ + struct appletb_kbd *kbd = container_of(work, struct appletb_kbd, + restore_brightness_work); + + if (kbd->backlight_dev) + backlight_device_set_brightness(kbd->backlight_dev, 2); +} + static void reset_inactivity_timer(struct appletb_kbd *kbd) { if (kbd->backlight_dev && appletb_tb_autodim) { if (kbd->has_dimmed || kbd->has_turned_off) { - backlight_device_set_brightness(kbd->backlight_dev, 2); kbd->has_dimmed = false; kbd->has_turned_off = false; + schedule_work(&kbd->restore_brightness_work); } - mod_timer(&kbd->inactivity_timer, - jiffies + secs_to_jiffies(appletb_tb_dim_timeout)); + mod_delayed_work(system_wq, &kbd->inactivity_work, + secs_to_jiffies(appletb_tb_dim_timeout)); } } @@ -408,9 +420,11 @@ static int appletb_kbd_probe(struct hid_device *hdev, const struct hid_device_id dev_err_probe(dev, -ENODEV, "Failed to get backlight device\n"); } else { backlight_device_set_brightness(kbd->backlight_dev, 2); - timer_setup(&kbd->inactivity_timer, appletb_inactivity_timer, 0); - mod_timer(&kbd->inactivity_timer, - jiffies + secs_to_jiffies(appletb_tb_dim_timeout)); + INIT_DELAYED_WORK(&kbd->inactivity_work, appletb_inactivity_work); + INIT_WORK(&kbd->restore_brightness_work, + appletb_restore_brightness_work); + mod_delayed_work(system_wq, &kbd->inactivity_work, + secs_to_jiffies(appletb_tb_dim_timeout)); } kbd->inp_handler.event = appletb_kbd_inp_event; @@ -444,7 +458,8 @@ close_hw: stop_hw: hid_hw_stop(hdev); if (kbd->backlight_dev) { - timer_delete_sync(&kbd->inactivity_timer); + cancel_delayed_work_sync(&kbd->inactivity_work); + cancel_work_sync(&kbd->restore_brightness_work); put_device(&kbd->backlight_dev->dev); } return ret; @@ -461,7 +476,8 @@ static void appletb_kbd_remove(struct hid_device *hdev) hid_hw_stop(hdev); if (kbd->backlight_dev) { - timer_delete_sync(&kbd->inactivity_timer); + cancel_delayed_work_sync(&kbd->inactivity_work); + cancel_work_sync(&kbd->restore_brightness_work); put_device(&kbd->backlight_dev->dev); } } -- 2.47.3