linux-kernel - Re: [PATCH v2 5/5] ACPI: property: Refactor acpi_data_prop_read

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Date:   Fri, 12 Feb 2021 15:31:24 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>
Subject: Re: [PATCH v2 5/5] ACPI: property: Refactor acpi_data_prop_read_single()

On Fri, Feb 12, 2021 at 3:14 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
 >
> Refactor acpi_data_prop_read_single() for less LOCs and better maintenance.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/acpi/property.c | 80 ++++++++++++++++++-----------------------
>  1 file changed, 34 insertions(+), 46 deletions(-)
>
> diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
> index e312ebaed8db..494cf283a573 100644
> --- a/drivers/acpi/property.c
> +++ b/drivers/acpi/property.c
> @@ -785,60 +785,48 @@ static int acpi_data_prop_read_single(const struct acpi_device_data *data,
>                                       enum dev_prop_type proptype, void *val)
>  {
>         const union acpi_object *obj;
> -       int ret;
> +       int ret = 0;
>
> -       if (proptype >= DEV_PROP_U8 && proptype <= DEV_PROP_U64) {
> +       if (proptype >= DEV_PROP_U8 && proptype <= DEV_PROP_U64)
>                 ret = acpi_data_get_property(data, propname, ACPI_TYPE_INTEGER, &obj);
> -               if (ret)
> -                       return ret;
> -
> -               switch (proptype) {
> -               case DEV_PROP_U8:
> -                       if (obj->integer.value > U8_MAX)
> -                               return -EOVERFLOW;
> -
> -                       if (val)
> -                               *(u8 *)val = obj->integer.value;
> -
> -                       break;

The empty lines of code above are intentional, so please retain them.

> -               case DEV_PROP_U16:
> -                       if (obj->integer.value > U16_MAX)
> -                               return -EOVERFLOW;
> -
> -                       if (val)
> -                               *(u16 *)val = obj->integer.value;
> -
> -                       break;
> -               case DEV_PROP_U32:
> -                       if (obj->integer.value > U32_MAX)
> -                               return -EOVERFLOW;
> -
> -                       if (val)
> -                               *(u32 *)val = obj->integer.value;
> -
> -                       break;
> -               default:
> -                       if (val)
> -                               *(u64 *)val = obj->integer.value;
> -
> -                       break;
> -               }
> -
> -               if (!val)
> -                       return 1;
> -       } else if (proptype == DEV_PROP_STRING) {
> +       else if (proptype == DEV_PROP_STRING)
>                 ret = acpi_data_get_property(data, propname, ACPI_TYPE_STRING, &obj);
> -               if (ret)
> -                       return ret;
> +       if (ret)
> +               return ret;

else if (!val)
        ret = 1;

>
> +       switch (proptype) {
> +       case DEV_PROP_U8:
> +               if (obj->integer.value > U8_MAX)
> +                       return -EOVERFLOW;
> +               if (val)
> +                       *(u8 *)val = obj->integer.value;
> +               break;
> +       case DEV_PROP_U16:
> +               if (obj->integer.value > U16_MAX)
> +                       return -EOVERFLOW;
> +               if (val)
> +                       *(u16 *)val = obj->integer.value;
> +               break;
> +       case DEV_PROP_U32:
> +               if (obj->integer.value > U32_MAX)
> +                       return -EOVERFLOW;
> +               if (val)
> +                       *(u32 *)val = obj->integer.value;
> +               break;
> +       case DEV_PROP_U64:
> +               if (val)
> +                       *(u64 *)val = obj->integer.value;
> +               break;
> +       case DEV_PROP_STRING:
>                 if (val)
>                         *(char **)val = obj->string.pointer;
> -
>                 return 1;
> -       } else {
> -               ret = -EINVAL;
> +       default:
> +               return -EINVAL;
>         }
> -       return ret;

Retain this.

> +
> +       /* When no storage provided return number of available values */
> +       return val ? 0 : 1;

And this is just not looking good to me, sorry.

>  }
>
>  static int acpi_copy_property_array_u8(const union acpi_object *items, u8 *val,
> --