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 <ezequiel@xxxxxxxxxxxxxxxxxxxx>
---
drivers/leds/led-triggers.c | 2 +-
drivers/leds/leds.h | 1 +
drivers/leds/trigger/Kconfig | 3 +++
drivers/leds/trigger/ledtrig-panic.c | 47 ++++++++++++++++++++++++++++++++++++
include/linux/leds.h | 1 +
5 files changed, 53 insertions(+), 1 deletion(-)
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..4e4521c9072a 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..3e447bd2064a 100644
--- a/drivers/leds/trigger/ledtrig-panic.c
+++ b/drivers/leds/trigger/ledtrig-panic.c
@@ -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 a 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;
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 19eb10278bea..7e9fb00e15e8 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -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
--
2.7.0
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