Re: [PATCH v2] PM / devfreq: passive: Use non-devm notifiers

[Chanwoo Choi <cw00.choi@samsung.com>]

Hi,

Why do you miss the 'Fixes' tag as I commented?
Is there any reason?

On 19. 8. 13. 오후 2:06, Leonard Crestez wrote:
> The devfreq passive governor registers and unregisters devfreq
> transition notifiers on DEVFREQ_GOV_START/GOV_STOP using devm wrappers.
> 
> If devfreq itself is registered with devm then a warning is triggered on
> rmmod from devm_devfreq_unregister_notifier. Call stack looks like this:
> 
> 	devm_devfreq_unregister_notifier+0x30/0x40
> 	devfreq_passive_event_handler+0x4c/0x88
> 	devfreq_remove_device.part.8+0x6c/0x9c
> 	devm_devfreq_dev_release+0x18/0x20
> 	release_nodes+0x1b0/0x220
> 	devres_release_all+0x78/0x84
> 	device_release_driver_internal+0x100/0x1c0
> 	driver_detach+0x4c/0x90
> 	bus_remove_driver+0x7c/0xd0
> 	driver_unregister+0x2c/0x58
> 	platform_driver_unregister+0x10/0x18
> 	imx_devfreq_platdrv_exit+0x14/0xd40 [imx_devfreq]
> 
> This happens because devres_release_all will first remove all the nodes
> into a separate todo list so the nested devres_release from
> devm_devfreq_unregister_notifier won't find anything.
> 
> Fix the warning by calling the non-devm APIS for frequency notification.
> Using devm wrappers is not actually useful for a governor anyway: it
> relies on the devfreq core to correctly match the GOV_START/GOV_STOP
> notifications.
> 
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
> Cc: stable@vger.kernel.org
> 
> ---
> Changes since v1:
> * Remove unused variable "dev" and avoid warning
> * Added ack and cc stable
> Link to v1: https://patchwork.kernel.org/patch/11084541/
> 
>  drivers/devfreq/governor_passive.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
> index 58308948b863..be6eeab9c814 100644
> --- a/drivers/devfreq/governor_passive.c
> +++ b/drivers/devfreq/governor_passive.c
> @@ -147,11 +147,10 @@ static int devfreq_passive_notifier_call(struct notifier_block *nb,
>  }
>  
>  static int devfreq_passive_event_handler(struct devfreq *devfreq,
>  				unsigned int event, void *data)
>  {
> -	struct device *dev = devfreq->dev.parent;
>  	struct devfreq_passive_data *p_data
>  			= (struct devfreq_passive_data *)devfreq->data;
>  	struct devfreq *parent = (struct devfreq *)p_data->parent;
>  	struct notifier_block *nb = &p_data->nb;
>  	int ret = 0;
> @@ -163,16 +162,16 @@ static int devfreq_passive_event_handler(struct devfreq *devfreq,
>  	case DEVFREQ_GOV_START:
>  		if (!p_data->this)
>  			p_data->this = devfreq;
>  
>  		nb->notifier_call = devfreq_passive_notifier_call;
> -		ret = devm_devfreq_register_notifier(dev, parent, nb,
> +		ret = devfreq_register_notifier(parent, nb,
>  					DEVFREQ_TRANSITION_NOTIFIER);
>  		break;
>  	case DEVFREQ_GOV_STOP:
> -		devm_devfreq_unregister_notifier(dev, parent, nb,
> -					DEVFREQ_TRANSITION_NOTIFIER);
> +		WARN_ON(devfreq_unregister_notifier(parent, nb,
> +					DEVFREQ_TRANSITION_NOTIFIER));
>  		break;
>  	default:
>  		break;
>  	}
>  
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

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