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authorEzequiel Garcia <ezequiel@vanguardiasur.com.ar>2016-04-28 19:03:38 -0300
committerJacek Anaszewski <j.anaszewski@samsung.com>2016-05-06 10:22:09 +0200
commitba93cdce5bbe6929fd7486f87c985598ded8f451 (patch)
treee9bedbf17709dceafabbcd753a3d6cc97c36d6fb /drivers/leds/trigger
parentf15c65afddbe16a832cfe3f311588c7e34a4efbf (diff)
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 <ezequiel@vanguardiasur.com.ar> Reviewed-by: Matthias Brugger <mbrugger@suse.com> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Diffstat (limited to 'drivers/leds/trigger')
-rw-r--r--drivers/leds/trigger/Kconfig3
-rw-r--r--drivers/leds/trigger/ledtrig-panic.c47
2 files changed, 50 insertions, 0 deletions
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 <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;