Subject: Re: [PATCH] cpuidle: fix unremovable issue for module driver

From: Daniel Lezcano <[email-masked]>
Date: Tue, 30 Jul 2013 11:28:15 +0200

On 07/30/2013 08:55 AM, Dongsheng Wang wrote:
> From: Wang Dongsheng <[email-masked]>
> 
> After __cpuidle_register_device, the cpu incs are added up, but decs
> are not, thus the module refcount is not match. So the module "exit"
> function can not be executed when we do remove operation. Move
> module_put into __cpuidle_register_device to fix it.

Sorry, I still don't get it :/

register->module_get
unregister->module_put

you change it by:

register->module_get
register->module_put
unregister->none

which is wrong.

Can you describe the problem you are facing ? (a bit more than "I can't
unload the module").

> Signed-off-by: Wang Dongsheng <[email-masked]>
> 
> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> index d75040d..e964ada 100644
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -351,11 +351,8 @@ EXPORT_SYMBOL_GPL(cpuidle_disable_device);
>  
>  static void __cpuidle_unregister_device(struct cpuidle_device *dev)
>  {
> -	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
> -
>  	list_del(&dev->device_list);
>  	per_cpu(cpuidle_devices, dev->cpu) = NULL;
> -	module_put(drv->owner);
>  }
>  
>  static int __cpuidle_device_init(struct cpuidle_device *dev)
> @@ -384,6 +381,8 @@ static int __cpuidle_register_device(struct cpuidle_device *dev)
>  	per_cpu(cpuidle_devices, dev->cpu) = dev;
>  	list_add(&dev->device_list, &cpuidle_detected_devices);
>  
> +	module_put(drv->owner);
> +
>  	ret = cpuidle_coupled_register_device(dev);
>  	if (ret) {
>  		__cpuidle_unregister_device(dev);
> 

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