From ba93cdce5bbe6929fd7486f87c985598ded8f451 Mon Sep 17 00:00:00 2001 From: Ezequiel Garcia Date: Thu, 28 Apr 2016 19:03:38 -0300 Subject: leds: triggers: Allow to switch the trigger to "panic" on a kernel panic This commit adds a new led_cdev flag LED_PANIC_INDICATOR, which allows to mark a specific LED to be switched to the "panic" trigger, on a kernel panic. This is useful to allow the user to assign a regular trigger to a given LED, and still blink that LED on a kernel panic. Signed-off-by: Ezequiel Garcia Reviewed-by: Matthias Brugger Acked-by: Pavel Machek Signed-off-by: Jacek Anaszewski --- drivers/leds/led-triggers.c | 2 +- drivers/leds/leds.h | 1 + drivers/leds/trigger/Kconfig | 3 +++ drivers/leds/trigger/ledtrig-panic.c | 47 ++++++++++++++++++++++++++++++++++++ 4 files changed, 52 insertions(+), 1 deletion(-) (limited to 'drivers/leds') diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c index 2181581795d3..55fa65e1ae03 100644 --- a/drivers/leds/led-triggers.c +++ b/drivers/leds/led-triggers.c @@ -26,7 +26,7 @@ * Nests outside led_cdev->trigger_lock */ static DECLARE_RWSEM(triggers_list_lock); -static LIST_HEAD(trigger_list); +LIST_HEAD(trigger_list); /* Used by LED Class */ diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h index db3f20da7221..7d38e6b9a740 100644 --- a/drivers/leds/leds.h +++ b/drivers/leds/leds.h @@ -30,5 +30,6 @@ void led_set_brightness_nosleep(struct led_classdev *led_cdev, extern struct rw_semaphore leds_list_lock; extern struct list_head leds_list; +extern struct list_head trigger_list; #endif /* __LEDS_H_INCLUDED */ diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig index beac8c31c51b..9893d911390d 100644 --- a/drivers/leds/trigger/Kconfig +++ b/drivers/leds/trigger/Kconfig @@ -121,6 +121,9 @@ config LEDS_TRIGGER_PANIC depends on LEDS_TRIGGERS help This allows LEDs to be configured to blink on a kernel panic. + Enabling this option will allow to mark certain LEDs as panic indicators, + allowing to blink them on a kernel panic, even if they are set to + a different trigger. If unsure, say Y. endif # LEDS_TRIGGERS diff --git a/drivers/leds/trigger/ledtrig-panic.c b/drivers/leds/trigger/ledtrig-panic.c index 627b350c5ec3..d735526b9db4 100644 --- a/drivers/leds/trigger/ledtrig-panic.c +++ b/drivers/leds/trigger/ledtrig-panic.c @@ -11,10 +11,54 @@ #include #include +#include #include +#include "../leds.h" static struct led_trigger *trigger; +/* + * This is called in a special context by the atomic panic + * notifier. This means the trigger can be changed without + * worrying about locking. + */ +static void led_trigger_set_panic(struct led_classdev *led_cdev) +{ + struct led_trigger *trig; + + list_for_each_entry(trig, &trigger_list, next_trig) { + if (strcmp("panic", trig->name)) + continue; + if (led_cdev->trigger) + list_del(&led_cdev->trig_list); + list_add_tail(&led_cdev->trig_list, &trig->led_cdevs); + + /* Avoid the delayed blink path */ + led_cdev->blink_delay_on = 0; + led_cdev->blink_delay_off = 0; + + led_cdev->trigger = trig; + if (trig->activate) + trig->activate(led_cdev); + break; + } +} + +static int led_trigger_panic_notifier(struct notifier_block *nb, + unsigned long code, void *unused) +{ + struct led_classdev *led_cdev; + + list_for_each_entry(led_cdev, &leds_list, node) + if (led_cdev->flags & LED_PANIC_INDICATOR) + led_trigger_set_panic(led_cdev); + return NOTIFY_DONE; +} + +static struct notifier_block led_trigger_panic_nb = { + .notifier_call = led_trigger_panic_notifier, +}; + static long led_panic_blink(int state) { led_trigger_event(trigger, state ? LED_FULL : LED_OFF); @@ -23,6 +67,9 @@ static long led_panic_blink(int state) static int __init ledtrig_panic_init(void) { + atomic_notifier_chain_register(&panic_notifier_list, + &led_trigger_panic_nb); + led_trigger_register_simple("panic", &trigger); panic_blink = led_panic_blink; return 0; -- cgit v1.2.3-59-g8ed1b