linux-kernel - Re: [PATCH 1/1] thermal: fix cpu_cooling max

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Date:	Sat, 4 Jan 2014 09:53:28 -0400
From:	Eduardo Valentin <eduardo.valentin@...com>
To:	Zhang Rui <rui.zhang@...el.com>
CC:	Eduardo Valentin <eduardo.valentin@...com>,
	<linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] thermal: fix cpu_cooling max_level behavior

On 02-01-2014 00:02, Zhang Rui wrote:
> On Fri, 2013-12-06 at 09:52 -0400, Eduardo Valentin wrote:
>> On 13-11-2013 14:11, Eduardo Valentin wrote:
>>> As per Documentation/thermal/sysfs-api.txt, max_level
>>> is an index, not a counter. Thus, in case a CPU has
>>> 3 valid frequencies, max_level is expected to be 2, for instance.
>>>
>>> The current code makes max_level == number of valid frequencies,
>>> which is bogus. This patch fix the cpu_cooling device by
>>> ranging max_level properly.
>>>
> good catch.
>>> Reported-by: Carlos Hernandez <ceh@...com>
>>> Signed-off-by: Eduardo Valentin <eduardo.valentin@...com>
>>
>> Rui,
>>
>> Can you please consider pushing this fix?
>>
> applied.
> 
>>> ---
>>>  drivers/thermal/cpu_cooling.c | 6 ++++--
>>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
>>> index d179028..d0f8f8b5 100644
>>> --- a/drivers/thermal/cpu_cooling.c
>>> +++ b/drivers/thermal/cpu_cooling.c
>>> @@ -173,6 +173,8 @@ static int get_property(unsigned int cpu, unsigned long input,
>>>  		freq = table[i].frequency;
>>>  		max_level++;
>>>  	}
>>> +	/* max_level is an index, not a counter */
>>> +	max_level--;
>>>
> I think we should check the max_level first, like the patch I attached
> below.
> 
> thanks,
> rui
> 
>>>From a116776f7b6052599df0c67db29c30ea9d69d7ee Mon Sep 17 00:00:00 2001
> From: Zhang Rui <rui.zhang@...el.com>
> Date: Thu, 2 Jan 2014 11:57:48 +0800
> Subject: [PATCH] Thermal cpu cooling: return error if no valid cpu frequency
>  entry
> 
> Signed-off-by: Zhang Rui <rui.zhang@...el.com>
> ---
>  drivers/thermal/cpu_cooling.c |    5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> index cc556a8..bb486b4 100644
> --- a/drivers/thermal/cpu_cooling.c
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -173,6 +173,11 @@ static int get_property(unsigned int cpu, unsigned long input,
>  		freq = table[i].frequency;
>  		max_level++;
>  	}
> +
> +	/* No valid cpu frequency entry */
> +	if (max_level == 0)
> +		return -EINVAL;
> +

Agreed. For the patch above:

Acked-by: Eduardo Valentin <eduardo.valentin@...com>

>  	/* max_level is an index, not a counter */
>  	max_level--;
>  
> 


-- 
You have got to be excited about what you are doing. (L. Lamport)

Eduardo Valentin


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