[PATCH v3] leds: trigger: netdev: skip setting baseline state in activate if hw-controlled

[PATCH v3] leds: trigger: netdev: skip setting baseline state in activate if hw-controlled

[Heiner Kallweit]

The current codes uses the sw_control path in set_baseline_state() when
called from netdev_trig_activate() even if we're hw-controlled. This
may result in errors when led_set_brightness() is called because we may
not have set_brightness led ops (if hw doesn't support setting a "LED"
to ON). In addition this path may schedule trigger_data->work which
doesn't make sense when being hw-controlled.

Therefore set trigger_data->hw_control = true before calling
set_device_name() from netdev_trig_activate(). In this call chain we
have to prevent set_baseline_state() from being called, because this
would call hw_control_set(). Use led_cdev->trigger_data == NULL as
indicator for being called from netdev_trig_activate().

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- improve commit message
v3:
- spelling and style fixes
---
 drivers/leds/trigger/ledtrig-netdev.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/leds/trigger/ledtrig-netdev.c b/drivers/leds/trigger/ledtrig-netdev.c
index 09e75fd9f..6cbba44dd 100644
--- a/drivers/leds/trigger/ledtrig-netdev.c
+++ b/drivers/leds/trigger/ledtrig-netdev.c
@@ -267,7 +267,10 @@ static int set_device_name(struct led_netdev_data *trigger_data,
 
 	trigger_data->last_activity = 0;
 
-	set_baseline_state(trigger_data);
+	/* Skip if we're called from netdev_trig_activate() and hw_control is true */
+	if (!trigger_data->hw_control || led_get_trigger_data(trigger_data->led_cdev))
+		set_baseline_state(trigger_data);
+
 	mutex_unlock(&trigger_data->lock);
 	rtnl_unlock();
 
@@ -602,8 +605,8 @@ static int netdev_trig_activate(struct led_classdev *led_cdev)
 		if (dev) {
 			const char *name = dev_name(dev);
 
-			set_device_name(trigger_data, name, strlen(name));
 			trigger_data->hw_control = true;
+			set_device_name(trigger_data, name, strlen(name));
 
 			rc = led_cdev->hw_control_get(led_cdev, &mode);
 			if (!rc)
-- 
2.43.0

Re: [PATCH v3] leds: trigger: netdev: skip setting baseline state in activate if hw-controlled

[Lee Jones]

On Thu, 21 Dec 2023, Heiner Kallweit wrote:

> The current codes uses the sw_control path in set_baseline_state() when
> called from netdev_trig_activate() even if we're hw-controlled. This
> may result in errors when led_set_brightness() is called because we may
> not have set_brightness led ops (if hw doesn't support setting a "LED"
> to ON). In addition this path may schedule trigger_data->work which
> doesn't make sense when being hw-controlled.
> 
> Therefore set trigger_data->hw_control = true before calling
> set_device_name() from netdev_trig_activate(). In this call chain we
> have to prevent set_baseline_state() from being called, because this
> would call hw_control_set(). Use led_cdev->trigger_data == NULL as
> indicator for being called from netdev_trig_activate().
> 
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
> v2:
> - improve commit message
> v3:
> - spelling and style fixes
> ---
>  drivers/leds/trigger/ledtrig-netdev.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)

Doesn't apply.  Please rebase it on top of the LEDs repo.

https://git.kernel.org/pub/scm/linux/kernel/git/lee/leds.git/

> diff --git a/drivers/leds/trigger/ledtrig-netdev.c b/drivers/leds/trigger/ledtrig-netdev.c
> index 09e75fd9f..6cbba44dd 100644
> --- a/drivers/leds/trigger/ledtrig-netdev.c
> +++ b/drivers/leds/trigger/ledtrig-netdev.c
> @@ -267,7 +267,10 @@ static int set_device_name(struct led_netdev_data *trigger_data,
>  
>  	trigger_data->last_activity = 0;
>  
> -	set_baseline_state(trigger_data);
> +	/* Skip if we're called from netdev_trig_activate() and hw_control is true */
> +	if (!trigger_data->hw_control || led_get_trigger_data(trigger_data->led_cdev))
> +		set_baseline_state(trigger_data);
> +
>  	mutex_unlock(&trigger_data->lock);
>  	rtnl_unlock();
>  
> @@ -602,8 +605,8 @@ static int netdev_trig_activate(struct led_classdev *led_cdev)
>  		if (dev) {
>  			const char *name = dev_name(dev);
>  
> -			set_device_name(trigger_data, name, strlen(name));
>  			trigger_data->hw_control = true;
> +			set_device_name(trigger_data, name, strlen(name));
>  
>  			rc = led_cdev->hw_control_get(led_cdev, &mode);
>  			if (!rc)
> -- 
> 2.43.0

-- 
Lee Jones [李琼斯]

Re: [PATCH v3] leds: trigger: netdev: skip setting baseline state in activate if hw-controlled

[Heiner Kallweit]

On 21.12.2023 17:27, Lee Jones wrote:
> On Thu, 21 Dec 2023, Heiner Kallweit wrote:
> 
>> The current codes uses the sw_control path in set_baseline_state() when
>> called from netdev_trig_activate() even if we're hw-controlled. This
>> may result in errors when led_set_brightness() is called because we may
>> not have set_brightness led ops (if hw doesn't support setting a "LED"
>> to ON). In addition this path may schedule trigger_data->work which
>> doesn't make sense when being hw-controlled.
>>
>> Therefore set trigger_data->hw_control = true before calling
>> set_device_name() from netdev_trig_activate(). In this call chain we
>> have to prevent set_baseline_state() from being called, because this
>> would call hw_control_set(). Use led_cdev->trigger_data == NULL as
>> indicator for being called from netdev_trig_activate().
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>> ---
>> v2:
>> - improve commit message
>> v3:
>> - spelling and style fixes
>> ---
>>  drivers/leds/trigger/ledtrig-netdev.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> Doesn't apply.  Please rebase it on top of the LEDs repo.
> 
It's because fe2b1226656a ("leds: trigger: netdev: fix RTNL handling to
prevent potential deadlock") was applied via the netdev tree.
I'll rebase on top of for-leds-next.

> https://git.kernel.org/pub/scm/linux/kernel/git/lee/leds.git/
> 
>> diff --git a/drivers/leds/trigger/ledtrig-netdev.c b/drivers/leds/trigger/ledtrig-netdev.c
>> index 09e75fd9f..6cbba44dd 100644
>> --- a/drivers/leds/trigger/ledtrig-netdev.c
>> +++ b/drivers/leds/trigger/ledtrig-netdev.c
>> @@ -267,7 +267,10 @@ static int set_device_name(struct led_netdev_data *trigger_data,
>>  
>>  	trigger_data->last_activity = 0;
>>  
>> -	set_baseline_state(trigger_data);
>> +	/* Skip if we're called from netdev_trig_activate() and hw_control is true */
>> +	if (!trigger_data->hw_control || led_get_trigger_data(trigger_data->led_cdev))
>> +		set_baseline_state(trigger_data);
>> +
>>  	mutex_unlock(&trigger_data->lock);
>>  	rtnl_unlock();
>>  
>> @@ -602,8 +605,8 @@ static int netdev_trig_activate(struct led_classdev *led_cdev)
>>  		if (dev) {
>>  			const char *name = dev_name(dev);
>>  
>> -			set_device_name(trigger_data, name, strlen(name));
>>  			trigger_data->hw_control = true;
>> +			set_device_name(trigger_data, name, strlen(name));
>>  
>>  			rc = led_cdev->hw_control_get(led_cdev, &mode);
>>  			if (!rc)
>> -- 
>> 2.43.0
>