kernel/linux.git/drivers/leds/led-core.c, branch v6.6.141

leds: Fix LED_OFF brightness race

2025-04-10T12:37:32+00:00

[ Upstream commit 2c70953b6f535f7698ccbf22c1f5ba26cb6c2816 ] While commit fa15d8c69238 ("leds: Fix set_brightness_delayed() race") successfully forces led_set_brightness() to be called with LED_OFF at least once when switching from blinking to LED on state so that hw-blinking can be disabled, another race remains. Indeed in led_set_brightness(LED_OFF) followed by led_set_brightness(any) scenario the following CPU scheduling can happen: CPU0 CPU1 ---- ---- set_brightness_delayed() { test_and_clear_bit(BRIGHTNESS_OFF) led_set_brightness(LED_OFF) { set_bit(BRIGHTNESS_OFF) queue_work() } led_set_brightness(any) { set_bit(BRIGHTNESS) queue_work() //already queued } test_and_clear_bit(BRIGHTNESS) /* LED set with brightness any */ } /* From previous CPU1 queue_work() */ set_brightness_delayed() { test_and_clear_bit(BRIGHTNESS_OFF) /* LED turned off */ test_and_clear_bit(BRIGHTNESS) /* Clear from previous run, LED remains off */ In that case the led_set_brightness(LED_OFF)/led_set_brightness(any) sequence will be effectively executed in reverse order and LED will remain off. With the introduction of commit 32360bf6a5d4 ("leds: Introduce ordered workqueue for LEDs events instead of system_wq") the race is easier to trigger as sysfs brightness configuration does not wait for set_brightness_delayed() work to finish (flush_work() removal). Use delayed_set_value to optionnally re-configure brightness after a LED_OFF. That way a LED state could be configured more that once but final state will always be as expected. Ensure that delayed_set_value modification is seen before set_bit() using smp_mb__before_atomic(). Fixes: fa15d8c69238 ("leds: Fix set_brightness_delayed() race") Signed-off-by: Remi Pommarel Reviewed-by: Hans de Goede Link: https://lore.kernel.org/r/19c81177059dab7b656c42063958011a8e4d1a66.1740050412.git.repk@triplefau.lt Signed-off-by: Lee Jones Signed-off-by: Sasha Levin

leds: Drop BUG_ON check for LED_COLOR_ID_MULTI

2023-09-19T14:16:23+00:00

Commit c3f853184bed ("leds: Fix BUG_ON check for LED_COLOR_ID_MULTI that is always false") fixed a no-op BUG_ON. This turned out to cause a regression, since some in-tree device-tree files already use LED_COLOR_ID_MULTI. Drop the BUG_ON altogether. Fixes: c3f853184bed ("leds: Fix BUG_ON check for LED_COLOR_ID_MULTI that is always false") Reported-by: Da Xue Closes: https://lore.kernel.org/linux-leds/ZQLelWcNjjp2xndY@duo.ucw.cz/T/ Signed-off-by: Marek Behún Link: https://lore.kernel.org/r/20230918140724.18634-1-kabel@kernel.org Signed-off-by: Lee Jones

leds: Fix BUG_ON check for LED_COLOR_ID_MULTI that is always false

2023-08-17T10:26:36+00:00

At the time we call BUG_ON(props.color == LED_COLOR_ID_MULTI); the props variable is still initialized to zero. Call the BUG_ON only after we parse fwnode into props. Fixes: 77dce3a22e89 ("leds: disallow /sys/class/leds/*:multi:* for now") Signed-off-by: Marek Behún Link: https://lore.kernel.org/r/20230801151623.30387-1-kabel@kernel.org Signed-off-by: Lee Jones

leds: Fix oops about sleeping in led_trigger_blink()

2023-05-25T11:16:31+00:00

led_trigger_blink() calls led_blink_set() from a RCU read-side critical section so led_blink_set() must not sleep. Note sleeping was not allowed before the switch to RCU either because a spinlock was held before. led_blink_set() does not sleep when sw-blinking is used, but many LED controller drivers with hw blink support have a blink_set function which may sleep, leading to an oops like this one: [ 832.605062] ------------[ cut here ]------------ [ 832.605085] Voluntary context switch within RCU read-side critical section! [ 832.605119] WARNING: CPU: 2 PID: 370 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0x4ee/0x690 [ 832.606453] Call Trace: [ 832.606466] [ 832.606487] __schedule+0x9f/0x1480 [ 832.606527] schedule+0x5d/0xe0 [ 832.606549] schedule_timeout+0x79/0x140 [ 832.606572] ? __pfx_process_timeout+0x10/0x10 [ 832.606599] wait_for_completion_timeout+0x6f/0x140 [ 832.606627] i2c_dw_xfer+0x101/0x460 [ 832.606659] ? psi_group_change+0x168/0x400 [ 832.606680] __i2c_transfer+0x172/0x6d0 [ 832.606709] i2c_smbus_xfer_emulated+0x27d/0x9c0 [ 832.606732] ? __schedule+0x430/0x1480 [ 832.606753] ? preempt_count_add+0x6a/0xa0 [ 832.606778] ? get_nohz_timer_target+0x18/0x190 [ 832.606796] ? lock_timer_base+0x61/0x80 [ 832.606817] ? preempt_count_add+0x6a/0xa0 [ 832.606842] __i2c_smbus_xfer+0xa2/0x3f0 [ 832.606862] i2c_smbus_xfer+0x66/0xf0 [ 832.606882] i2c_smbus_read_byte_data+0x41/0x70 [ 832.606901] ? _raw_spin_unlock_irqrestore+0x23/0x40 [ 832.606922] ? __pm_runtime_suspend+0x46/0xc0 [ 832.606946] cht_wc_byte_reg_read+0x2e/0x60 [ 832.606972] _regmap_read+0x5c/0x120 [ 832.606997] _regmap_update_bits+0x96/0xc0 [ 832.607023] regmap_update_bits_base+0x5b/0x90 [ 832.607053] cht_wc_leds_brightness_get+0x412/0x910 [leds_cht_wcove] [ 832.607094] led_blink_setup+0x28/0x100 [ 832.607119] led_trigger_blink+0x40/0x70 [ 832.607145] power_supply_update_leds+0x1b7/0x1c0 [ 832.607174] power_supply_changed_work+0x67/0xe0 [ 832.607198] process_one_work+0x1c8/0x3c0 [ 832.607222] worker_thread+0x4d/0x380 [ 832.607243] ? __pfx_worker_thread+0x10/0x10 [ 832.607258] kthread+0xe9/0x110 [ 832.607279] ? __pfx_kthread+0x10/0x10 [ 832.607300] ret_from_fork+0x2c/0x50 [ 832.607337] [ 832.607344] ---[ end trace 0000000000000000 ]--- Add a new led_blink_set_nosleep() function which defers the actual led_blink_set() call to a workqueue when necessary to fix this. This also fixes an existing race where a pending led_set_brightness() has been deferred to set_brightness_work and might then race with a later led_cdev->blink_set() call. Note this race is only an issue with triggers mixing led_trigger_event() and led_trigger_blink() calls, sysfs API calls and led_trigger_blink_oneshot() are not affected. Note rather then adding a separate blink_set_blocking callback this uses the presence of the already existing brightness_set_blocking callback to detect if the blinking call should be deferred to set_brightness_work. Signed-off-by: Hans de Goede Reviewed-by: Jacek Anaszewski Tested-by: Yauhen Kharuzhy Link: https://lore.kernel.org/r/20230510162234.291439-4-hdegoede@redhat.com Signed-off-by: Lee Jones

leds: Fix set_brightness_delayed() race

2023-05-25T11:16:30+00:00

When a trigger wants to switch from blinking to LED on it needs to call: led_set_brightness(LED_OFF); led_set_brightness(LED_FULL); To first call disables blinking and the second then turns the LED on (the power-supply charging-blink-full-solid triggers do this). These calls happen immediately after each other, so it is possible that set_brightness_delayed() from the first call has not run yet when the led_set_brightness(LED_FULL) call finishes. If this race hits then this is causing problems for both sw- and hw-blinking: For sw-blinking set_brightness_delayed() clears delayed_set_value when LED_BLINK_DISABLE is set causing the led_set_brightness(LED_FULL) call effects to get lost when hitting the race, resulting in the LED turning off instead of on. For hw-blinking if the race hits delayed_set_value has been set to LED_FULL by the time set_brightness_delayed() runs. So led_cdev->brightness_set_blocking() is never called with LED_OFF as argument and the hw-blinking is never disabled leaving the LED blinking instead of on. Fix both issues by adding LED_SET_BRIGHTNESS and LED_SET_BRIGHTNESS_OFF work_flags making this 2 separate actions to be run by set_brightness_delayed(). Signed-off-by: Hans de Goede Reviewed-by: Jacek Anaszewski Tested-by: Yauhen Kharuzhy Link: https://lore.kernel.org/r/20230510162234.291439-3-hdegoede@redhat.com Signed-off-by: Lee Jones

leds: move default_state read from fwnode to core

2021-08-18T06:27:30+00:00

This patch introduces a new function to read initial default_state from fwnode. Suggested-by: Pavel Machek Signed-off-by: Denis Osterland-Heim Signed-off-by: Pavel Machek

leds: led-core: Get rid of enum led_brightness

2021-02-19T10:35:28+00:00

This gets rid of enum led_brightness in the main led files, because it is deprecated, and an unsigned int can be used instead. We can get rid of led_brightness completely and patches can also be supplied for the other drivers' files. Signed-off-by: Abanoub Sameh Signed-off-by: Pavel Machek

leds: disallow /sys/class/leds/:multi: for now

2020-08-03T12:00:06+00:00

All the LEDs in the queue are RGB, so they should not use multi for their color. Make sure we don't add such LED by mistake (and make it part of ABI). Signed-off-by: Pavel Machek

leds: add RGB color option, as that is different from multicolor.

2020-08-03T11:26:15+00:00

Multicolor is a bit too abstract. Yes, we can have Green-Magenta-Ultraviolet LED, but so far all the LEDs we support are RGB, and not even RGB-White or RGB-Yellow variants emerged. Multicolor is not a good fit for RGB LED. It does not really know about LED color. In particular, there's no way to make LED "white". Userspace is interested in knowing "this LED can produce arbitrary color", which not all multicolor LEDs can. Signed-off-by: Pavel Machek

leds: Add multicolor ID to the color ID list

2020-07-15T17:33:16+00:00

Add a new color ID that is declared as MULTICOLOR as with the multicolor framework declaring a definitive color is not accurate as the node can contain multiple colors. Signed-off-by: Dan Murphy Reviewed-by: Marek Behún Signed-off-by: Pavel Machek