lkml.org 
[lkml]   [2016]   [Apr]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/5] leds: triggers: Allow to switch the trigger to "panic" on a kernel panic
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

\
 
 \ /
  Last update: 2016-04-25 09:21    [W:2.540 / U:0.192 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site