[PATCH v1 2/2] thermal: sysfs: Add sanity checks for trip temperature and hysteresis

Posted by Rafael J. Wysocki 1 year, 5 months ago

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Add sanity checks for new trip temperature and hysteresis values to
trip_point_temp_store() and trip_point_hyst_store() to prevent trip
point thresholds from falling below THERMAL_TEMP_INVALID.

However, still allow user space to pass THERMAL_TEMP_INVALID as the
new trip temperature value to invalidate the trip if necessary.

Fixes: be0a3600aa1e ("thermal: sysfs: Rework the handling of trip point updates")
Cc: 6.8+ <stable@vger.kernel.org> # 6.8+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/thermal/thermal_sysfs.c |   38 ++++++++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 12 deletions(-)

Index: linux-pm/drivers/thermal/thermal_sysfs.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_sysfs.c
+++ linux-pm/drivers/thermal/thermal_sysfs.c
@@ -111,18 +111,25 @@ trip_point_temp_store(struct device *dev
 
 	mutex_lock(&tz->lock);
 
-	if (temp != trip->temperature) {
-		if (tz->ops.set_trip_temp) {
-			ret = tz->ops.set_trip_temp(tz, trip, temp);
-			if (ret)
-				goto unlock;
-		}
+	if (temp == trip->temperature)
+		goto unlock;
 
-		thermal_zone_set_trip_temp(tz, trip, temp);
+	if (temp != THERMAL_TEMP_INVALID &&
+	    temp <= trip->hysteresis + THERMAL_TEMP_INVALID) {
+		ret = -EINVAL;
+		goto unlock;
+	}
 
-		__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
+	if (tz->ops.set_trip_temp) {
+		ret = tz->ops.set_trip_temp(tz, trip, temp);
+		if (ret)
+			goto unlock;
 	}
 
+	thermal_zone_set_trip_temp(tz, trip, temp);
+
+	__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
+
 unlock:
 	mutex_unlock(&tz->lock);
 
@@ -152,15 +159,22 @@ trip_point_hyst_store(struct device *dev
 
 	mutex_lock(&tz->lock);
 
-	if (hyst != trip->hysteresis) {
-		thermal_zone_set_trip_hyst(tz, trip, hyst);
+	if (hyst == trip->hysteresis)
+		goto unlock;
 
-		__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
+	if (hyst + THERMAL_TEMP_INVALID >= trip->temperature) {
+		ret = -EINVAL;
+		goto unlock;
 	}
 
+	thermal_zone_set_trip_hyst(tz, trip, hyst);
+
+	__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
+
+unlock:
 	mutex_unlock(&tz->lock);
 
-	return count;
+	return ret ? ret : count;
 }
 
 static ssize_t

Re: [PATCH v1 2/2] thermal: sysfs: Add sanity checks for trip temperature and hysteresis

Posted by Daniel Lezcano 1 year, 5 months ago

On 22/08/2024 21:48, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Add sanity checks for new trip temperature and hysteresis values to
> trip_point_temp_store() and trip_point_hyst_store() to prevent trip
> point thresholds from falling below THERMAL_TEMP_INVALID.
> 
> However, still allow user space to pass THERMAL_TEMP_INVALID as the
> new trip temperature value to invalidate the trip if necessary.
> 
> Fixes: be0a3600aa1e ("thermal: sysfs: Rework the handling of trip point updates")
> Cc: 6.8+ <stable@vger.kernel.org> # 6.8+
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>   drivers/thermal/thermal_sysfs.c |   38 ++++++++++++++++++++++++++------------
>   1 file changed, 26 insertions(+), 12 deletions(-)
> 
> Index: linux-pm/drivers/thermal/thermal_sysfs.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_sysfs.c
> +++ linux-pm/drivers/thermal/thermal_sysfs.c
> @@ -111,18 +111,25 @@ trip_point_temp_store(struct device *dev
>   
>   	mutex_lock(&tz->lock);
>   
> -	if (temp != trip->temperature) {
> -		if (tz->ops.set_trip_temp) {
> -			ret = tz->ops.set_trip_temp(tz, trip, temp);
> -			if (ret)
> -				goto unlock;
> -		}
> +	if (temp == trip->temperature)
> +		goto unlock;
>   
> -		thermal_zone_set_trip_temp(tz, trip, temp);
> +	if (temp != THERMAL_TEMP_INVALID &&
> +	    temp <= trip->hysteresis + THERMAL_TEMP_INVALID) {

It seems to me the condition is hard to understand.

   temp <= trip->hysteresis + THERMAL_TEMP_INVALID

	  ==>

   temp - trip->hysteresis <= THERMAL_TEMP_INVALID


Could be the test below simpler to understand ?

	if (trip->hysteresis &&
	    temp - trip->hysteresis < THERMAL_TEMP_INVALID))

I think more sanity check may be needed also.

	if (temp < THERMAL_TEMP_INVALID)

> +		ret = -EINVAL;
> +		goto unlock;
> +	}
>   
> -		__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
> +	if (tz->ops.set_trip_temp) {
> +		ret = tz->ops.set_trip_temp(tz, trip, temp);
> +		if (ret)
> +			goto unlock;
>   	}
>   
> +	thermal_zone_set_trip_temp(tz, trip, temp);
> +
> +	__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
> +
>   unlock:
>   	mutex_unlock(&tz->lock);
>   
> @@ -152,15 +159,22 @@ trip_point_hyst_store(struct device *dev
>   
>   	mutex_lock(&tz->lock);
>   
> -	if (hyst != trip->hysteresis) {
> -		thermal_zone_set_trip_hyst(tz, trip, hyst);
> +	if (hyst == trip->hysteresis)
> +		goto unlock;
>   
> -		__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
> +	if (hyst + THERMAL_TEMP_INVALID >= trip->temperature) {
> +		ret = -EINVAL;
> +		goto unlock;
>   	}
>   
> +	thermal_zone_set_trip_hyst(tz, trip, hyst);
> +
> +	__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
> +
> +unlock:
>   	mutex_unlock(&tz->lock);
>   
> -	return count;
> +	return ret ? ret : count;
>   }
>   
>   static ssize_t
> 
> 
> 


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Re: [PATCH v1 2/2] thermal: sysfs: Add sanity checks for trip temperature and hysteresis

Posted by Rafael J. Wysocki 1 year, 5 months ago

On Fri, Aug 23, 2024 at 5:26 PM Daniel Lezcano
<daniel.lezcano@linaro.org> wrote:
>
> On 22/08/2024 21:48, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > Add sanity checks for new trip temperature and hysteresis values to
> > trip_point_temp_store() and trip_point_hyst_store() to prevent trip
> > point thresholds from falling below THERMAL_TEMP_INVALID.
> >
> > However, still allow user space to pass THERMAL_TEMP_INVALID as the
> > new trip temperature value to invalidate the trip if necessary.
> >
> > Fixes: be0a3600aa1e ("thermal: sysfs: Rework the handling of trip point updates")
> > Cc: 6.8+ <stable@vger.kernel.org> # 6.8+
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
> >   drivers/thermal/thermal_sysfs.c |   38 ++++++++++++++++++++++++++------------
> >   1 file changed, 26 insertions(+), 12 deletions(-)
> >
> > Index: linux-pm/drivers/thermal/thermal_sysfs.c
> > ===================================================================
> > --- linux-pm.orig/drivers/thermal/thermal_sysfs.c
> > +++ linux-pm/drivers/thermal/thermal_sysfs.c
> > @@ -111,18 +111,25 @@ trip_point_temp_store(struct device *dev
> >
> >       mutex_lock(&tz->lock);
> >
> > -     if (temp != trip->temperature) {
> > -             if (tz->ops.set_trip_temp) {
> > -                     ret = tz->ops.set_trip_temp(tz, trip, temp);
> > -                     if (ret)
> > -                             goto unlock;
> > -             }
> > +     if (temp == trip->temperature)
> > +             goto unlock;
> >
> > -             thermal_zone_set_trip_temp(tz, trip, temp);
> > +     if (temp != THERMAL_TEMP_INVALID &&
> > +         temp <= trip->hysteresis + THERMAL_TEMP_INVALID) {
>
> It seems to me the condition is hard to understand.

That's not the key consideration here though.

>
>    temp <= trip->hysteresis + THERMAL_TEMP_INVALID

This cannot overflow because trip->hysteresis is non-negative.

>
>           ==>
>
>    temp - trip->hysteresis <= THERMAL_TEMP_INVALID

But this can.

>
>
> Could be the test below simpler to understand ?
>
>         if (trip->hysteresis &&
>             temp - trip->hysteresis < THERMAL_TEMP_INVALID))
>
> I think more sanity check may be needed also.
>
>         if (temp < THERMAL_TEMP_INVALID)

With my version of the check above this is not necessary (unless I'm
missing something}.

> > +             ret = -EINVAL;
> > +             goto unlock;
> > +     }

Re: [PATCH v1 2/2] thermal: sysfs: Add sanity checks for trip temperature and hysteresis

Posted by Rafael J. Wysocki 1 year, 5 months ago

On Fri, Aug 23, 2024 at 6:39 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Fri, Aug 23, 2024 at 5:26 PM Daniel Lezcano
> <daniel.lezcano@linaro.org> wrote:
> >
> > On 22/08/2024 21:48, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > >
> > > Add sanity checks for new trip temperature and hysteresis values to
> > > trip_point_temp_store() and trip_point_hyst_store() to prevent trip
> > > point thresholds from falling below THERMAL_TEMP_INVALID.
> > >
> > > However, still allow user space to pass THERMAL_TEMP_INVALID as the
> > > new trip temperature value to invalidate the trip if necessary.
> > >
> > > Fixes: be0a3600aa1e ("thermal: sysfs: Rework the handling of trip point updates")
> > > Cc: 6.8+ <stable@vger.kernel.org> # 6.8+
> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > ---
> > >   drivers/thermal/thermal_sysfs.c |   38 ++++++++++++++++++++++++++------------
> > >   1 file changed, 26 insertions(+), 12 deletions(-)
> > >
> > > Index: linux-pm/drivers/thermal/thermal_sysfs.c
> > > ===================================================================
> > > --- linux-pm.orig/drivers/thermal/thermal_sysfs.c
> > > +++ linux-pm/drivers/thermal/thermal_sysfs.c
> > > @@ -111,18 +111,25 @@ trip_point_temp_store(struct device *dev
> > >
> > >       mutex_lock(&tz->lock);
> > >
> > > -     if (temp != trip->temperature) {
> > > -             if (tz->ops.set_trip_temp) {
> > > -                     ret = tz->ops.set_trip_temp(tz, trip, temp);
> > > -                     if (ret)
> > > -                             goto unlock;
> > > -             }
> > > +     if (temp == trip->temperature)
> > > +             goto unlock;
> > >
> > > -             thermal_zone_set_trip_temp(tz, trip, temp);
> > > +     if (temp != THERMAL_TEMP_INVALID &&
> > > +         temp <= trip->hysteresis + THERMAL_TEMP_INVALID) {
> >
> > It seems to me the condition is hard to understand.
>
> That's not the key consideration here though.
>
> >
> >    temp <= trip->hysteresis + THERMAL_TEMP_INVALID
>
> This cannot overflow because trip->hysteresis is non-negative.
>
> >
> >           ==>
> >
> >    temp - trip->hysteresis <= THERMAL_TEMP_INVALID
>
> But this can.

Well, I think I should add a comment there to point that out or people
will try to "clean it up".

Also note that in the hysteresis case the condition can be

if (trip->temperature - hyst <= THERMAL_TEMP_INVALID) {

because trip->temperature is never below THERMAL_TEMP_INVALID there.

Moreover, setting the hysteresis when the temperature is
THERMAL_TRIP_INVALID does not make much sense.

I'll send a v2.

> >
> >
> > Could be the test below simpler to understand ?
> >
> >         if (trip->hysteresis &&
> >             temp - trip->hysteresis < THERMAL_TEMP_INVALID))
> >
> > I think more sanity check may be needed also.
> >
> >         if (temp < THERMAL_TEMP_INVALID)
>
> With my version of the check above this is not necessary (unless I'm
> missing something}.
>
> > > +             ret = -EINVAL;
> > > +             goto unlock;
> > > +     }