[PATCH v1 1/1] thermal: sysfs: switch to use scnprintf() to suppress truncation warning

[PATCH v1 1/1] thermal: sysfs: switch to use scnprintf() to suppress truncation warning

[Andy Shevchenko]

Switch the sysfs code to use scnprintf() to avoid warnings about potential
truncation of the names of the sysfs attributes. We can't increase the buffer
size because the size is the part of an ABI for some reason. Note, with
the current size of buffer the affected attributes have a room for up to
1000 names, which ought to be enough for all cases. There is no functional
change, as the same limitation was implied before.

Fixes: c56f5c0342df ("Thermal: Make Thermal trip points writeable")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/thermal/thermal_sysfs.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index b44abfc997ed..44bd7c50e4ac 100644
--- a/drivers/thermal/thermal_sysfs.c
+++ b/drivers/thermal/thermal_sysfs.c
@@ -400,8 +400,8 @@ static int create_trip_attrs(struct thermal_zone_device *tz)
 		struct thermal_trip_attrs *trip_attrs = &td->trip_attrs;
 
 		/* create trip type attribute */
-		snprintf(trip_attrs->type.name, THERMAL_NAME_LENGTH,
-			 "trip_point_%d_type", i);
+		scnprintf(trip_attrs->type.name, sizeof(trip_attrs->type.name),
+			  "trip_point_%d_type", i);
 
 		sysfs_attr_init(&trip_attrs->type.attr.attr);
 		trip_attrs->type.attr.attr.name = trip_attrs->type.name;
@@ -410,8 +410,8 @@ static int create_trip_attrs(struct thermal_zone_device *tz)
 		attrs[i] = &trip_attrs->type.attr.attr;
 
 		/* create trip temp attribute */
-		snprintf(trip_attrs->temp.name, THERMAL_NAME_LENGTH,
-			 "trip_point_%d_temp", i);
+		scnprintf(trip_attrs->temp.name, sizeof(trip_attrs->temp.name),
+			  "trip_point_%d_temp", i);
 
 		sysfs_attr_init(&trip_attrs->temp.attr.attr);
 		trip_attrs->temp.attr.attr.name = trip_attrs->temp.name;
@@ -423,8 +423,8 @@ static int create_trip_attrs(struct thermal_zone_device *tz)
 		}
 		attrs[i + tz->num_trips] = &trip_attrs->temp.attr.attr;
 
-		snprintf(trip_attrs->hyst.name, THERMAL_NAME_LENGTH,
-			 "trip_point_%d_hyst", i);
+		scnprintf(trip_attrs->hyst.name, sizeof(trip_attrs->hyst.name),
+			  "trip_point_%d_hyst", i);
 
 		sysfs_attr_init(&trip_attrs->hyst.attr.attr);
 		trip_attrs->hyst.attr.attr.name = trip_attrs->hyst.name;
-- 
2.50.1

Re: [PATCH v1 1/1] thermal: sysfs: switch to use scnprintf() to suppress truncation warning

[Andy Shevchenko]

On Mon, Aug 17, 2026 at 12:33:24PM +0200, Andy Shevchenko wrote:
> Switch the sysfs code to use scnprintf() to avoid warnings about potential
> truncation of the names of the sysfs attributes. We can't increase the buffer
> size because the size is the part of an ABI for some reason. Note, with
> the current size of buffer the affected attributes have a room for up to
> 1000 names, which ought to be enough for all cases. There is no functional
> change, as the same limitation was implied before.

I still have the build issues, can we get this applied to v7.3-rcX, please?

> Fixes: c56f5c0342df ("Thermal: Make Thermal trip points writeable")

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 1/1] thermal: sysfs: switch to use scnprintf() to suppress truncation warning

[Lukasz Luba]

On 8/17/26 11:33, Andy Shevchenko wrote:
> Switch the sysfs code to use scnprintf() to avoid warnings about potential
> truncation of the names of the sysfs attributes. We can't increase the buffer
> size because the size is the part of an ABI for some reason. Note, with
> the current size of buffer the affected attributes have a room for up to
> 1000 names, which ought to be enough for all cases. There is no functional
> change, as the same limitation was implied before.

Right, it doesn't touch the real truncation check problem only avoids
the complain from the tool. We can think about this later in some
redesign.

> 
> Fixes: c56f5c0342df ("Thermal: Make Thermal trip points writeable")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>   drivers/thermal/thermal_sysfs.c | 12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)


Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>

Re: [PATCH v1 1/1] thermal: sysfs: switch to use scnprintf() to suppress truncation warning

[Rafael J. Wysocki (Intel)]

On Fri, Sep 4, 2026 at 10:01 AM Lukasz Luba <lukasz.luba@arm.com> wrote:
>
>
>
> On 8/17/26 11:33, Andy Shevchenko wrote:
> > Switch the sysfs code to use scnprintf() to avoid warnings about potential
> > truncation of the names of the sysfs attributes. We can't increase the buffer
> > size because the size is the part of an ABI for some reason. Note, with
> > the current size of buffer the affected attributes have a room for up to
> > 1000 names, which ought to be enough for all cases. There is no functional
> > change, as the same limitation was implied before.
>
> Right, it doesn't touch the real truncation check problem only avoids
> the complain from the tool. We can think about this later in some
> redesign.
>
> >
> > Fixes: c56f5c0342df ("Thermal: Make Thermal trip points writeable")
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > ---
> >   drivers/thermal/thermal_sysfs.c | 12 ++++++------
> >   1 file changed, 6 insertions(+), 6 deletions(-)
>
>
> Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>

Applied and added to linux-pm.git/fixes, thanks!

Re: [PATCH v1 1/1] thermal: sysfs: switch to use scnprintf() to suppress truncation warning

[David Laight]

On Mon, 17 Aug 2026 12:33:24 +0200
Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:

> Switch the sysfs code to use scnprintf() to avoid warnings about potential
> truncation of the names of the sysfs attributes.

It has to be a 'bug' that 'format overflow' warnings are generated for
snprintf() but not for scnprintf().
They really shouldn't behave differently.

I did some tests a while back and the warning goes away if you do
'some things' with the result (like comparing against the buffer size),
but even explicitly ignoring it with a (void) cast isn't enough.

Using OPTIMIZER_HIDE_VAR() (or an _VAL variant) on the buffer size does
stop the error, but I expect gcc to start checking sizeof(buf) as well.
So both arguments might need hiding to get the warning ignored.

David

> We can't increase the buffer
> size because the size is the part of an ABI for some reason. Note, with
> the current size of buffer the affected attributes have a room for up to
> 1000 names, which ought to be enough for all cases. There is no functional
> change, as the same limitation was implied before.
> 
> Fixes: c56f5c0342df ("Thermal: Make Thermal trip points writeable")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/thermal/thermal_sysfs.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
> index b44abfc997ed..44bd7c50e4ac 100644
> --- a/drivers/thermal/thermal_sysfs.c
> +++ b/drivers/thermal/thermal_sysfs.c
> @@ -400,8 +400,8 @@ static int create_trip_attrs(struct thermal_zone_device *tz)
>  		struct thermal_trip_attrs *trip_attrs = &td->trip_attrs;
>  
>  		/* create trip type attribute */
> -		snprintf(trip_attrs->type.name, THERMAL_NAME_LENGTH,
> -			 "trip_point_%d_type", i);
> +		scnprintf(trip_attrs->type.name, sizeof(trip_attrs->type.name),
> +			  "trip_point_%d_type", i);
>  
>  		sysfs_attr_init(&trip_attrs->type.attr.attr);
>  		trip_attrs->type.attr.attr.name = trip_attrs->type.name;
> @@ -410,8 +410,8 @@ static int create_trip_attrs(struct thermal_zone_device *tz)
>  		attrs[i] = &trip_attrs->type.attr.attr;
>  
>  		/* create trip temp attribute */
> -		snprintf(trip_attrs->temp.name, THERMAL_NAME_LENGTH,
> -			 "trip_point_%d_temp", i);
> +		scnprintf(trip_attrs->temp.name, sizeof(trip_attrs->temp.name),
> +			  "trip_point_%d_temp", i);
>  
>  		sysfs_attr_init(&trip_attrs->temp.attr.attr);
>  		trip_attrs->temp.attr.attr.name = trip_attrs->temp.name;
> @@ -423,8 +423,8 @@ static int create_trip_attrs(struct thermal_zone_device *tz)
>  		}
>  		attrs[i + tz->num_trips] = &trip_attrs->temp.attr.attr;
>  
> -		snprintf(trip_attrs->hyst.name, THERMAL_NAME_LENGTH,
> -			 "trip_point_%d_hyst", i);
> +		scnprintf(trip_attrs->hyst.name, sizeof(trip_attrs->hyst.name),
> +			  "trip_point_%d_hyst", i);
>  
>  		sysfs_attr_init(&trip_attrs->hyst.attr.attr);
>  		trip_attrs->hyst.attr.attr.name = trip_attrs->hyst.name;