linux-kernel - Re: [PATCH v3 2/5] thermal: rockchip: fix a impossible condition caused by the warning

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Message-ID: <20151203201908.GA34901@dtor-ws>
Date:	Thu, 3 Dec 2015 12:19:08 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Caesar Wang <wxt@...k-chips.com>
Cc:	Eduardo Valentin <edubezval@...il.com>, huangtao@...k-chips.com,
	Heiko Stuebner <heiko@...ech.de>, dianders@...omium.org,
	linux-rockchip@...ts.infradead.org, computersforpeace@...il.com,
	Dan Carpenter <dan.carpenter@...cle.com>,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Zhang Rui <rui.zhang@...el.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 2/5] thermal: rockchip: fix a impossible condition
 caused by the warning

On Thu, Dec 03, 2015 at 04:48:40PM +0800, Caesar Wang wrote:
> As the Dan report the smatch check the thermal driver warning:
> drivers/thermal/rockchip_thermal.c:551 rockchip_configure_from_dt()
> warn: impossible condition '(thermal->tshut_temp > ((~0 >> 1))) =>
> (s32min-s32max > s32max)'
> 
> Let's we remove the imposssible condition Since the Temperature is
> currently represented as int not long in the thermal driver.
> 
> Fixes: commit 437df2172e8d
> ("thermal: rockchip: consistently use int for temperatures")
> 
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Signed-off-by: Caesar Wang <wxt@...k-chips.com>
> 
> ---
> 
> Changes in v3:
> - As Brian comments on https://patchwork.kernel.org/patch/7580661/,
>   let's remove the impossible condition.
> 
> Changes in v2: None
> Changes in v1: None
> 
>  drivers/thermal/rockchip_thermal.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/thermal/rockchip_thermal.c b/drivers/thermal/rockchip_thermal.c
> index ae796ec..611de00 100644
> --- a/drivers/thermal/rockchip_thermal.c
> +++ b/drivers/thermal/rockchip_thermal.c
> @@ -549,12 +549,6 @@ static int rockchip_configure_from_dt(struct device *dev,
>  		thermal->tshut_temp = shut_temp;
>  	}
>  
> -	if (thermal->tshut_temp > INT_MAX) {
> -		dev_err(dev, "Invalid tshut temperature specified: %d\n",
> -			thermal->tshut_temp);
> -		return -ERANGE;
> -	}

Well, that is not entirely correct. The value that we read from DT is
u32, but we convert it down to int. I believe you want to move the check
up so that you do:

	} else if (tshut_temp > INT_MAX) {
		dev_err(dev, "Invalid tshut temperature specified: %d\n",
			thermal->tshut_temp);
		return -ERANGE;
	} else {
		thermal->tshut_temp = shut_temp;
	}

Thanks.

-- 
Dmitry
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