Re: [PATCH v2] drm/xe/hwmon: Use overflows_type() for temperature range check

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 23 Oct 2026, Mallesh Koujalagi <mallesh.koujalagi@intel.com> wrote:
> The temperature value is calculated as an s64 before being stored
> in a long. Check whether the value fits in the target type using
> overflows_type() instead of comparing against LONG_MAX directly.
>
> This keeps the overflow check correct on both 32-bit and 64-bit
> systems and avoids architecture-specific handling.
>
> Fixes: 24ec15d64617 ("drm/xe/hwmon: Decode CRI temperature registers as IEEE-754")
> Signed-off-by: Mallesh Koujalagi <mallesh.koujalagi@intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
> v2:
> - Use overflows_type(), instead of #ifdef. (Jani)
> ---
>  drivers/gpu/drm/xe/xe_hwmon.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_hwmon.c b/drivers/gpu/drm/xe/xe_hwmon.c
> index 42acfeb8818c..515b288f18e5 100644
> --- a/drivers/gpu/drm/xe/xe_hwmon.c
> +++ b/drivers/gpu/drm/xe/xe_hwmon.c
> @@ -6,6 +6,7 @@
>  #include <linux/hwmon-sysfs.h>
>  #include <linux/hwmon.h>
>  #include <linux/jiffies.h>
> +#include <linux/overflow.h>
>  #include <linux/types.h>
>  #include <linux/units.h>
>  
> @@ -1322,8 +1323,8 @@ static int xe_hwmon_temperature_decode(u32 reg_val, long *temperature)
>  		value = 0;
>  	}
>  
> -	/* Ensure the magnitude fits in long, which is 32-bit on some arches. */
> -	if (value > LONG_MAX)
> +	/* Ensure the decoded value fits in a long. */
> +	if (overflows_type(value, *temperature))
>  		return -ERANGE;
>  
>  	if (reg_val & IEEE754_SIGN)

-- 
Jani Nikula, Intel