Commit ba93cdce authored by Ezequiel Garcia's avatar Ezequiel Garcia Committed by Jacek Anaszewski
Browse files

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: default avatarEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Reviewed-by: default avatarMatthias Brugger <mbrugger@suse.com>
Acked-by: default avatarPavel Machek <pavel@ucw.cz>
Signed-off-by: default avatarJacek Anaszewski <j.anaszewski@samsung.com>
parent f15c65af

drivers/leds/led-triggers.c

+1 −1
Original line number Diff line number Diff line
@@ -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 */

drivers/leds/leds.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

drivers/leds/trigger/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -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

drivers/leds/trigger/ledtrig-panic.c

+47 −0
Original line number Diff line number Diff line
@@ -11,10 +11,54 @@ 


#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/notifier.h>

#include <linux/leds.h>

#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;

include/linux/leds.h

+1 −0
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ struct led_classdev { 
#define LED_SYSFS_DISABLE	(1 << 22)

#define LED_DEV_CAP_FLASH	(1 << 23)

#define LED_HW_PLUGGABLE	(1 << 24)

#define LED_PANIC_INDICATOR	(1 << 25)



	/* Set LED brightness level

	 * Must not sleep. Use brightness_set_blocking for drivers

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