[2/5] leds: triggers: Add a led_trigger_event_nosleep API
diff mbox series

Message ID 1459801326-5541-3-git-send-email-ezequiel@vanguardiasur.com.ar
State New, archived
Headers show
Series
  • Extend the LED panic trigger
Related show

Commit Message

Ezequiel Garcia April 4, 2016, 8:22 p.m. UTC
Now that we can mark any LED (even those in use by delayed blink
triggers) to trigger on a kernel panic, let's introduce a nosleep
led_trigger_event API.

This API is needed to skip the delayed blink path on
led_trigger_event. LEDs that are switched on a kernel panic,
might be in use by a delayed blink trigger.

This will be used by the panic LED trigger.

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
---
 drivers/leds/led-triggers.c | 26 ++++++++++++++++++++++----
 include/linux/leds.h        |  4 ++++
 2 files changed, 26 insertions(+), 4 deletions(-)

Comments

Jacek Anaszewski April 5, 2016, 9:36 p.m. UTC | #1
Hi Ezequiel,

On 04/04/2016 10:22 PM, Ezequiel Garcia wrote:
> Now that we can mark any LED (even those in use by delayed blink
> triggers) to trigger on a kernel panic, let's introduce a nosleep
> led_trigger_event API.
>
> This API is needed to skip the delayed blink path on
> led_trigger_event. LEDs that are switched on a kernel panic,
> might be in use by a delayed blink trigger.
>
> This will be used by the panic LED trigger.
>
> Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
> ---
>   drivers/leds/led-triggers.c | 26 ++++++++++++++++++++++----
>   include/linux/leds.h        |  4 ++++
>   2 files changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
> index f5c9d7c4d181..00b9d8497777 100644
> --- a/drivers/leds/led-triggers.c
> +++ b/drivers/leds/led-triggers.c
> @@ -307,8 +307,9 @@ EXPORT_SYMBOL_GPL(devm_led_trigger_register);
>
>   /* Simple LED Tigger Interface */
>
> -void led_trigger_event(struct led_trigger *trig,
> -			enum led_brightness brightness)
> +static void do_led_trigger_event(struct led_trigger *trig,
> +				 enum led_brightness brightness,
> +				 bool nosleep)
>   {
>   	struct led_classdev *led_cdev;
>
> @@ -316,12 +317,29 @@ void led_trigger_event(struct led_trigger *trig,
>   		return;
>
>   	read_lock(&trig->leddev_list_lock);
> -	list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
> -		led_set_brightness(led_cdev, brightness);

led_set_brightness() can gently disable blinking if passed 0 in the
brightness argument. IMHO this patch is not needed then.

> +	list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
> +		if (nosleep)
> +			led_set_brightness_nosleep(led_cdev, brightness);
> +		else
> +			led_set_brightness(led_cdev, brightness);
> +	}
>   	read_unlock(&trig->leddev_list_lock);
>   }
> +
> +void led_trigger_event(struct led_trigger *trig,
> +		       enum led_brightness brightness)
> +{
> +	do_led_trigger_event(trig, brightness, false);
> +}
>   EXPORT_SYMBOL_GPL(led_trigger_event);
>
> +void led_trigger_event_nosleep(struct led_trigger *trig,
> +			       enum led_brightness brightness)
> +{
> +	do_led_trigger_event(trig, brightness, true);
> +}
> +EXPORT_SYMBOL_GPL(led_trigger_event_nosleep);
> +
>   static void led_trigger_blink_setup(struct led_trigger *trig,
>   			     unsigned long *delay_on,
>   			     unsigned long *delay_off,
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 7f1428bb1e69..d33b230ce66d 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -259,6 +259,8 @@ extern void led_trigger_register_simple(const char *name,
>   extern void led_trigger_unregister_simple(struct led_trigger *trigger);
>   extern void led_trigger_event(struct led_trigger *trigger,
>   				enum led_brightness event);
> +extern void led_trigger_event_nosleep(struct led_trigger *trigger,
> +				enum led_brightness event);
>   extern void led_trigger_blink(struct led_trigger *trigger,
>   			      unsigned long *delay_on,
>   			      unsigned long *delay_off);
> @@ -305,6 +307,8 @@ static inline void led_trigger_register_simple(const char *name,
>   static inline void led_trigger_unregister_simple(struct led_trigger *trigger) {}
>   static inline void led_trigger_event(struct led_trigger *trigger,
>   				enum led_brightness event) {}
> +static inline void led_trigger_event_nosleep(struct led_trigger *trigger,
> +				enum led_brightness event) {}
>   static inline void led_trigger_blink(struct led_trigger *trigger,
>   				      unsigned long *delay_on,
>   				      unsigned long *delay_off) {}
>
Ezequiel Garcia April 6, 2016, 4:38 a.m. UTC | #2
On 5 April 2016 at 18:36, Jacek Anaszewski <jacek.anaszewski@gmail.com> wrote:
> Hi Ezequiel,
>
>
> On 04/04/2016 10:22 PM, Ezequiel Garcia wrote:
>>
>> Now that we can mark any LED (even those in use by delayed blink
>> triggers) to trigger on a kernel panic, let's introduce a nosleep
>> led_trigger_event API.
>>
>> This API is needed to skip the delayed blink path on
>> led_trigger_event. LEDs that are switched on a kernel panic,
>> might be in use by a delayed blink trigger.
>>
>> This will be used by the panic LED trigger.
>>
>> Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
>> ---
>>   drivers/leds/led-triggers.c | 26 ++++++++++++++++++++++----
>>   include/linux/leds.h        |  4 ++++
>>   2 files changed, 26 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
>> index f5c9d7c4d181..00b9d8497777 100644
>> --- a/drivers/leds/led-triggers.c
>> +++ b/drivers/leds/led-triggers.c
>> @@ -307,8 +307,9 @@ EXPORT_SYMBOL_GPL(devm_led_trigger_register);
>>
>>   /* Simple LED Tigger Interface */
>>
>> -void led_trigger_event(struct led_trigger *trig,
>> -                       enum led_brightness brightness)
>> +static void do_led_trigger_event(struct led_trigger *trig,
>> +                                enum led_brightness brightness,
>> +                                bool nosleep)
>>   {
>>         struct led_classdev *led_cdev;
>>
>> @@ -316,12 +317,29 @@ void led_trigger_event(struct led_trigger *trig,
>>                 return;
>>
>>         read_lock(&trig->leddev_list_lock);
>> -       list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
>> -               led_set_brightness(led_cdev, brightness);
>
>
> led_set_brightness() can gently disable blinking if passed 0 in the
> brightness argument. IMHO this patch is not needed then.
>
>

Yes, but the blinking disable is deferred, and so might never
run (e.g. I'd say it won't run on a non-preemptible kernel).

I think we need this API, or otherwise some way of circumventing
the deferred path on led_set_brightness. For instance, we
could turn off delay_on and delay_off in the panic atomic notifier.

I'm not strongly convinced by any approach, but this API seemed
slightly cleaner.
Jacek Anaszewski April 6, 2016, 6:12 a.m. UTC | #3
On 04/06/2016 06:38 AM, Ezequiel Garcia wrote:
> On 5 April 2016 at 18:36, Jacek Anaszewski <jacek.anaszewski@gmail.com> wrote:
>> Hi Ezequiel,
>>
>>
>> On 04/04/2016 10:22 PM, Ezequiel Garcia wrote:
>>>
>>> Now that we can mark any LED (even those in use by delayed blink
>>> triggers) to trigger on a kernel panic, let's introduce a nosleep
>>> led_trigger_event API.
>>>
>>> This API is needed to skip the delayed blink path on
>>> led_trigger_event. LEDs that are switched on a kernel panic,
>>> might be in use by a delayed blink trigger.
>>>
>>> This will be used by the panic LED trigger.
>>>
>>> Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
>>> ---
>>>    drivers/leds/led-triggers.c | 26 ++++++++++++++++++++++----
>>>    include/linux/leds.h        |  4 ++++
>>>    2 files changed, 26 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
>>> index f5c9d7c4d181..00b9d8497777 100644
>>> --- a/drivers/leds/led-triggers.c
>>> +++ b/drivers/leds/led-triggers.c
>>> @@ -307,8 +307,9 @@ EXPORT_SYMBOL_GPL(devm_led_trigger_register);
>>>
>>>    /* Simple LED Tigger Interface */
>>>
>>> -void led_trigger_event(struct led_trigger *trig,
>>> -                       enum led_brightness brightness)
>>> +static void do_led_trigger_event(struct led_trigger *trig,
>>> +                                enum led_brightness brightness,
>>> +                                bool nosleep)
>>>    {
>>>          struct led_classdev *led_cdev;
>>>
>>> @@ -316,12 +317,29 @@ void led_trigger_event(struct led_trigger *trig,
>>>                  return;
>>>
>>>          read_lock(&trig->leddev_list_lock);
>>> -       list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
>>> -               led_set_brightness(led_cdev, brightness);
>>
>>
>> led_set_brightness() can gently disable blinking if passed 0 in the
>> brightness argument. IMHO this patch is not needed then.
>>
>>
>
> Yes, but the blinking disable is deferred, and so might never
> run (e.g. I'd say it won't run on a non-preemptible kernel).
>
> I think we need this API, or otherwise some way of circumventing
> the deferred path on led_set_brightness. For instance, we
> could turn off delay_on and delay_off in the panic atomic notifier.

Yes, I prefer the latter, as it requires less changes.

> I'm not strongly convinced by any approach, but this API seemed
> slightly cleaner.
>

Patch
diff mbox series

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index f5c9d7c4d181..00b9d8497777 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -307,8 +307,9 @@  EXPORT_SYMBOL_GPL(devm_led_trigger_register);
 
 /* Simple LED Tigger Interface */
 
-void led_trigger_event(struct led_trigger *trig,
-			enum led_brightness brightness)
+static void do_led_trigger_event(struct led_trigger *trig,
+				 enum led_brightness brightness,
+				 bool nosleep)
 {
 	struct led_classdev *led_cdev;
 
@@ -316,12 +317,29 @@  void led_trigger_event(struct led_trigger *trig,
 		return;
 
 	read_lock(&trig->leddev_list_lock);
-	list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
-		led_set_brightness(led_cdev, brightness);
+	list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
+		if (nosleep)
+			led_set_brightness_nosleep(led_cdev, brightness);
+		else
+			led_set_brightness(led_cdev, brightness);
+	}
 	read_unlock(&trig->leddev_list_lock);
 }
+
+void led_trigger_event(struct led_trigger *trig,
+		       enum led_brightness brightness)
+{
+	do_led_trigger_event(trig, brightness, false);
+}
 EXPORT_SYMBOL_GPL(led_trigger_event);
 
+void led_trigger_event_nosleep(struct led_trigger *trig,
+			       enum led_brightness brightness)
+{
+	do_led_trigger_event(trig, brightness, true);
+}
+EXPORT_SYMBOL_GPL(led_trigger_event_nosleep);
+
 static void led_trigger_blink_setup(struct led_trigger *trig,
 			     unsigned long *delay_on,
 			     unsigned long *delay_off,
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 7f1428bb1e69..d33b230ce66d 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -259,6 +259,8 @@  extern void led_trigger_register_simple(const char *name,
 extern void led_trigger_unregister_simple(struct led_trigger *trigger);
 extern void led_trigger_event(struct led_trigger *trigger,
 				enum led_brightness event);
+extern void led_trigger_event_nosleep(struct led_trigger *trigger,
+				enum led_brightness event);
 extern void led_trigger_blink(struct led_trigger *trigger,
 			      unsigned long *delay_on,
 			      unsigned long *delay_off);
@@ -305,6 +307,8 @@  static inline void led_trigger_register_simple(const char *name,
 static inline void led_trigger_unregister_simple(struct led_trigger *trigger) {}
 static inline void led_trigger_event(struct led_trigger *trigger,
 				enum led_brightness event) {}
+static inline void led_trigger_event_nosleep(struct led_trigger *trigger,
+				enum led_brightness event) {}
 static inline void led_trigger_blink(struct led_trigger *trigger,
 				      unsigned long *delay_on,
 				      unsigned long *delay_off) {}