Re: [PATCH] cpuidle: Check cpuidle driver before add refcount

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Friday, August 30, 2013 07:48:22 PM Daniel Fu wrote:
> If the current CPU has no cpuidle driver, drv will be NULL.
> Check if we get drv successfully before add refount
> to prevent Kernel panic.

What is the actual scenario that may lead to this panic?

Rafael


> Signed-off-by: Daniel Fu <danifu@nvidia.com>
> ---
>  drivers/cpuidle/driver.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
> index 3ac499d..6e11701 100644
> --- a/drivers/cpuidle/driver.c
> +++ b/drivers/cpuidle/driver.c
> @@ -331,7 +331,8 @@ struct cpuidle_driver *cpuidle_driver_ref(void)
>  	spin_lock(&cpuidle_driver_lock);
>  
>  	drv = cpuidle_get_driver();
> -	drv->refcnt++;
> +	if (drv)
> +		drv->refcnt++;
>  
>  	spin_unlock(&cpuidle_driver_lock);
>  	return drv;
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.