Change a lot of min_t() that might mask high bits

[PATCH 13/44] drivers/acpi: use min() instead of min_t()

Posted by david.laight.linux@gmail.com 1 week, 5 days ago

From: David Laight <david.laight.linux@gmail.com>

min_t(unsigned int, a, b) casts an 'unsigned long' to 'unsigned int'.
Use min(a, b) instead as it promotes any 'unsigned int' to 'unsigned long'
and so cannot discard significant bits.

In this case the 'unsigned long' value is small enough that the result
is ok.

Detected by an extra check added to min_t().

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
 drivers/acpi/property.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index 43d5e457814e..e427ab24cde7 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -1280,7 +1280,7 @@ static int acpi_data_prop_read(const struct acpi_device_data *data,
 		ret = acpi_copy_property_array_uint(items, (u64 *)val, nval);
 		break;
 	case DEV_PROP_STRING:
-		nval = min_t(u32, nval, obj->package.count);
+		nval = min(nval, obj->package.count);
 		if (nval == 0)
 			return -ENODATA;
 
-- 
2.39.5

Re: [PATCH 13/44] drivers/acpi: use min() instead of min_t()

Posted by Rafael J. Wysocki 1 week ago

On Wed, Nov 19, 2025 at 11:42 PM <david.laight.linux@gmail.com> wrote:
>
> From: David Laight <david.laight.linux@gmail.com>
>
> min_t(unsigned int, a, b) casts an 'unsigned long' to 'unsigned int'.
> Use min(a, b) instead as it promotes any 'unsigned int' to 'unsigned long'
> and so cannot discard significant bits.
>
> In this case the 'unsigned long' value is small enough that the result
> is ok.
>
> Detected by an extra check added to min_t().
>
> Signed-off-by: David Laight <david.laight.linux@gmail.com>
> ---
>  drivers/acpi/property.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
> index 43d5e457814e..e427ab24cde7 100644
> --- a/drivers/acpi/property.c
> +++ b/drivers/acpi/property.c
> @@ -1280,7 +1280,7 @@ static int acpi_data_prop_read(const struct acpi_device_data *data,
>                 ret = acpi_copy_property_array_uint(items, (u64 *)val, nval);
>                 break;
>         case DEV_PROP_STRING:
> -               nval = min_t(u32, nval, obj->package.count);
> +               nval = min(nval, obj->package.count);
>                 if (nval == 0)
>                         return -ENODATA;
>
> --

Applied as 6.19 material with adjusted subject, thanks!