Subject: Re: [PATCH] Thermal: Fix synchronization issues in thermal_sys.c

From: Zhang Rui <[email-masked]>
Date: Thu, 27 Sep 2012 14:14:44 +0800

On 四, 2012-09-27 at 11:38 +0530, Durgadoss R wrote:
> This patch fixes the following mutex and NULL pointer
> problems in thermal_sys.c:
>  * mutex_unlock fix in update_temperature function
>  * mutex_unlock/NULL check fix in bind_cdev function
>  * NULL check fix in bind_tz function
> 
> Signed-off-by: Durgadoss R <[email-masked]>
> ---
>  drivers/thermal/thermal_sys.c |    9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c
> index 4f77d89..848553d 100644
> --- a/drivers/thermal/thermal_sys.c
> +++ b/drivers/thermal/thermal_sys.c
> @@ -252,8 +252,8 @@ static void bind_cdev(struct thermal_cooling_device *cdev)
>  		}
>  
>  		tzp = pos->tzp;
> -		if (!tzp->tbp)
> -			return;
> +		if (!tzp || !tzp->tbp)
> +			continue;
>  
>  		for (i = 0; i < tzp->num_tbps; i++) {
>  			if (tzp->tbp[i].cdev || !tzp->tbp[i].match)
> @@ -289,7 +289,7 @@ static void bind_tz(struct thermal_zone_device *tz)
>  		goto exit;
>  	}
>  
> -	if (!tzp->tbp)
> +	if (!tzp || !tzp->tbp)
>  		goto exit;
>  
actually, this is not a problem.
I checked the code just now, tzp can not be NULL if the code runs here.

>  	list_for_each_entry(pos, &thermal_cdev_list, node) {
> @@ -390,12 +390,13 @@ static void update_temperature(struct thermal_zone_device *tz)
>  	ret = tz->ops->get_temp(tz, &temp);
>  	if (ret) {
>  		pr_warn("failed to read out thermal zone %d\n", tz->id);
> -		return;
> +		goto exit;
>  	}
>  
>  	tz->last_temperature = tz->temperature;
>  	tz->temperature = temp;
>  
> +exit:
>  	mutex_unlock(&tz->lock);
>  }
>  

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