linux-kernel - Re: [PATCH v3] cpuidle/coupled: Add sanity check for safe_state

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Date:	Thu, 03 Sep 2015 03:35:15 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Xunlei Pang <xlpang@....com>
Cc:	linux-kernel@...r.kernel.org,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	linux-pm@...r.kernel.org, Xunlei Pang <pang.xunlei@...aro.org>
Subject: Re: [PATCH v3] cpuidle/coupled: Add sanity check for safe_state_index

On Monday, August 31, 2015 11:34:05 AM Xunlei Pang wrote:
> From: Xunlei Pang <pang.xunlei@...aro.org>
> 
> Since we are using cpuidle_driver::safe_state_index directly as the
> target state index, it is better to add the sanity check at the point
> of registering the driver.
> 
> Signed-off-by: Xunlei Pang <pang.xunlei@...aro.org>

I'm queuing this one up for the next PM pull request, thanks!


> ---
> v2->v3:
> Move the code to a new cpuidle_coupled_state_verify() depending on 
> CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED, to avoid using #ifdef in function 
> bodies. Thanks Rafael's comments on this.
> 
>  drivers/cpuidle/coupled.c | 22 ++++++++++++++++++++++
>  drivers/cpuidle/cpuidle.h |  6 ++++++
>  drivers/cpuidle/driver.c  |  4 ++++
>  3 files changed, 32 insertions(+)
> 
> diff --git a/drivers/cpuidle/coupled.c b/drivers/cpuidle/coupled.c
> index 1523e2d..344058f 100644
> --- a/drivers/cpuidle/coupled.c
> +++ b/drivers/cpuidle/coupled.c
> @@ -187,6 +187,28 @@ bool cpuidle_state_is_coupled(struct cpuidle_driver *drv, int state)
>  }
>  
>  /**
> + * cpuidle_coupled_state_verify - check if the coupled states are correctly set.
> + * @drv: struct cpuidle_driver for the platform
> + *
> + * Returns 0 for valid state values, a negative error code otherwise:
> + *  * -EINVAL if any coupled state(safe_state_index) is wrongly set.
> + */
> +int cpuidle_coupled_state_verify(struct cpuidle_driver *drv)
> +{
> +	int i;
> +
> +	for (i = drv->state_count - 1; i >= 0; i--) {
> +		if (cpuidle_state_is_coupled(drv, i) &&
> +		    (drv->safe_state_index == i ||
> +		     drv->safe_state_index < 0 ||
> +		     drv->safe_state_index >= drv->state_count))
> +			return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
>   * cpuidle_coupled_set_ready - mark a cpu as ready
>   * @coupled: the struct coupled that contains the current cpu
>   */
> diff --git a/drivers/cpuidle/cpuidle.h b/drivers/cpuidle/cpuidle.h
> index 178c5ad..f87f399 100644
> --- a/drivers/cpuidle/cpuidle.h
> +++ b/drivers/cpuidle/cpuidle.h
> @@ -35,6 +35,7 @@ extern void cpuidle_remove_sysfs(struct cpuidle_device *dev);
>  
>  #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
>  bool cpuidle_state_is_coupled(struct cpuidle_driver *drv, int state);
> +int cpuidle_coupled_state_verify(struct cpuidle_driver *drv);
>  int cpuidle_enter_state_coupled(struct cpuidle_device *dev,
>  		struct cpuidle_driver *drv, int next_state);
>  int cpuidle_coupled_register_device(struct cpuidle_device *dev);
> @@ -46,6 +47,11 @@ bool cpuidle_state_is_coupled(struct cpuidle_driver *drv, int state)
>  	return false;
>  }
>  
> +static inline int cpuidle_coupled_state_verify(struct cpuidle_driver *drv)
> +{
> +	return 0;
> +}
> +
>  static inline int cpuidle_enter_state_coupled(struct cpuidle_device *dev,
>  		struct cpuidle_driver *drv, int next_state)
>  {
> diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
> index 5db1478..389ade4 100644
> --- a/drivers/cpuidle/driver.c
> +++ b/drivers/cpuidle/driver.c
> @@ -227,6 +227,10 @@ static int __cpuidle_register_driver(struct cpuidle_driver *drv)
>  	if (!drv || !drv->state_count)
>  		return -EINVAL;
>  
> +	ret = cpuidle_coupled_state_verify(drv);
> +	if (ret)
> +		return ret;
> +
>  	if (cpuidle_disabled())
>  		return -ENODEV;
>  
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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