Messages in this thread | | | Date | Mon, 25 Apr 2016 08:56:46 +0200 | From | Jacek Anaszewski <> | Subject | Re: [PATCH 1/5] leds: triggers: Allow to switch the trigger to "panic" on a kernel panic |
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On 04/24/2016 11:29 AM, Pavel Machek wrote: > On Sun 2016-04-24 11:25:51, Pavel Machek wrote: >> On Mon 2016-04-04 17:22:02, Ezequiel Garcia wrote: >>> This commit adds a new led_cdev flag LED_BLINK_AT_PANIC, 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> >> >> >>> drivers/leds/led-triggers.c | 52 +++++++++++++++++++++++++++++++++++++++++++++ >>> include/linux/leds.h | 1 + >> >> Could we get this out of the core? I'm pretty sure most users are not >> interested...
Good point.
> Thinking about it some more.... > > This is not really a trigger. This is very special. Maybe hard-coded > handling, like we do for keyboard leds on x86 would be suitable?
Could you please spot the piece of code you have on mind?
> > >> >> Pavel >> >>> +/* >>> + * 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); >>> + 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_BLINK_AT_PANIC) >>> + led_trigger_set_panic(led_cdev); >>> + return NOTIFY_DONE; >>> +} >>> + >>> +static struct notifier_block led_trigger_panic_nb = { >>> + .notifier_call = led_trigger_panic_notifier, >>> +}; >>> + >>> void led_trigger_set_default(struct led_classdev *led_cdev) >>> { >>> struct led_trigger *trig; >>> @@ -356,6 +393,21 @@ void led_trigger_unregister_simple(struct led_trigger *trig) >>> } >>> EXPORT_SYMBOL_GPL(led_trigger_unregister_simple); >>> >>> +static int __init leds_trigger_init(void) >>> +{ >>> + atomic_notifier_chain_register(&panic_notifier_list, >>> + &led_trigger_panic_nb); >>> + return 0; >>> +} >>> + >>> +static void __exit leds_trigger_exit(void) >>> +{ >>> + atomic_notifier_chain_unregister(&panic_notifier_list, >>> + &led_trigger_panic_nb); >>> +} >>> +module_init(leds_trigger_init); >>> +module_exit(leds_trigger_exit); >>> + >>> MODULE_AUTHOR("Richard Purdie"); >>> MODULE_LICENSE("GPL"); >>> MODULE_DESCRIPTION("LED Triggers Core"); >>> diff --git a/include/linux/leds.h b/include/linux/leds.h >>> index f203a8f89d30..7f1428bb1e69 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_BLINK_AT_PANIC (1 << 25) >>> >>> /* Set LED brightness level >>> * Must not sleep. Use brightness_set_blocking for drivers >> >
-- Best regards, Jacek Anaszewski
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