[v3,2/5] thermal: rockchip: fix a impossible condition caused by the warning
diff mbox

Message ID 1449132523-18817-3-git-send-email-wxt@rock-chips.com
State New
Headers show

Commit Message

Caesar Wang Dec. 3, 2015, 8:48 a.m. UTC
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@oracle.com>
Signed-off-by: Caesar Wang <wxt@rock-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(-)

Comments

Dmitry Torokhov Dec. 3, 2015, 8:19 p.m. UTC | #1
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@oracle.com>
> Signed-off-by: Caesar Wang <wxt@rock-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.
Brian Norris Dec. 3, 2015, 8:33 p.m. UTC | #2
On Thu, Dec 03, 2015 at 12:19:08PM -0800, Dmitry Torokhov wrote:
> 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@oracle.com>
> > Signed-off-by: Caesar Wang <wxt@rock-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

Do we really account for the possibility of sizeof(int) < sizeof(u32)?

EDIT: A bit after writing the above line, I notice my error, but in case
anyone else is thinking the same thing... I guess you're referring to
the sign bit, since we're casting unsigned to signed.

Brian

> 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 Torokhov Dec. 3, 2015, 8:35 p.m. UTC | #3
On Thu, Dec 03, 2015 at 12:33:57PM -0800, Brian Norris wrote:
> On Thu, Dec 03, 2015 at 12:19:08PM -0800, Dmitry Torokhov wrote:
> > 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@oracle.com>
> > > Signed-off-by: Caesar Wang <wxt@rock-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
> 
> Do we really account for the possibility of sizeof(int) < sizeof(u32)?
> 
> EDIT: A bit after writing the above line, I notice my error, but in case
> anyone else is thinking the same thing... I guess you're referring to
> the sign bit, since we're casting unsigned to signed.

Yes, exactly. Sorry I was not clear.
Caesar Wang Dec. 20, 2015, 7:50 a.m. UTC | #4
? 2015?12?04? 04:19, Dmitry Torokhov ??:
> 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@oracle.com>
>> Signed-off-by: Caesar Wang <wxt@rock-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;
> 	}

Okay,
that's seem the following wll be resonable since the checkcode is a warning.

if (of_property_read_u32(np, "rockchip,hw-tshut-temp", &shut_temp)) {
         dev_warn(dev,
              "Missing tshut temp property, using default %d\n",
              thermal->chip->tshut_temp);
         thermal->tshut_temp = thermal->chip->tshut_temp;
     } else {
         if (tshut_temp > INT_MAX) {
             dev_err(dev, "Invalid tshut temperature specified: %d\n",
                 tshut_temp);
             return -ERANGE;
         }
         thermal->tshut_temp = shut_temp;
     }

Thanks,


> Thanks.
>

Patch
diff mbox

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;
-	}
-
 	if (of_property_read_u32(np, "rockchip,hw-tshut-mode", &tshut_mode)) {
 		dev_warn(dev,
 			 "Missing tshut mode property, using default (%s)\n",