diff options
| author | Hans de Goede <johannes.goede@oss.qualcomm.com> | 2025-12-11 17:37:27 +0100 |
|---|---|---|
| committer | Lee Jones <lee@kernel.org> | 2026-01-20 16:02:01 +0000 |
| commit | d1883cefd31752f0504b94c3bcfa1f6d511d6e87 (patch) | |
| tree | efa4a452b6b06eb21a3a0851d1bd3d5d991bdabc /drivers/leds | |
| parent | 8f0b4cce4481fb22653697cced8d0d04027cb1e8 (diff) | |
leds: led-class: Only Add LED to leds_list when it is fully ready
Before this change the LED was added to leds_list before led_init_core()
gets called adding it the list before led_classdev.set_brightness_work gets
initialized.
This leaves a window where led_trigger_register() of a LED's default
trigger will call led_trigger_set() which calls led_set_brightness()
which in turn will end up queueing the *uninitialized*
led_classdev.set_brightness_work.
This race gets hit by the lenovo-thinkpad-t14s EC driver which registers
2 LEDs with a default trigger provided by snd_ctl_led.ko in quick
succession. The first led_classdev_register() causes an async modprobe of
snd_ctl_led to run and that async modprobe manages to exactly hit
the window where the second LED is on the leds_list without led_init_core()
being called for it, resulting in:
------------[ cut here ]------------
WARNING: CPU: 11 PID: 5608 at kernel/workqueue.c:4234 __flush_work+0x344/0x390
Hardware name: LENOVO 21N2S01F0B/21N2S01F0B, BIOS N42ET93W (2.23 ) 09/01/2025
...
Call trace:
__flush_work+0x344/0x390 (P)
flush_work+0x2c/0x50
led_trigger_set+0x1c8/0x340
led_trigger_register+0x17c/0x1c0
led_trigger_register_simple+0x84/0xe8
snd_ctl_led_init+0x40/0xf88 [snd_ctl_led]
do_one_initcall+0x5c/0x318
do_init_module+0x9c/0x2b8
load_module+0x7e0/0x998
Close the race window by moving the adding of the LED to leds_list to
after the led_init_core() call.
Cc: stable@vger.kernel.org
Fixes: d23a22a74fde ("leds: delay led_set_brightness if stopping soft-blink")
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Reviewed-by: Sebastian Reichel <sre@kernel.org>
Link: https://patch.msgid.link/20251211163727.366441-1-johannes.goede@oss.qualcomm.com
Signed-off-by: Lee Jones <lee@kernel.org>
Diffstat (limited to 'drivers/leds')
| -rw-r--r-- | drivers/leds/led-class.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index 885399ed0776..d34a19453560 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -560,11 +560,6 @@ int led_classdev_register_ext(struct device *parent, #ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED led_cdev->brightness_hw_changed = -1; #endif - /* add to the list of leds */ - down_write(&leds_list_lock); - list_add_tail(&led_cdev->node, &leds_list); - up_write(&leds_list_lock); - if (!led_cdev->max_brightness) led_cdev->max_brightness = LED_FULL; @@ -574,6 +569,11 @@ int led_classdev_register_ext(struct device *parent, led_init_core(led_cdev); + /* add to the list of leds */ + down_write(&leds_list_lock); + list_add_tail(&led_cdev->node, &leds_list); + up_write(&leds_list_lock); + #ifdef CONFIG_LEDS_TRIGGERS led_trigger_set_default(led_cdev); #endif |