linux-kernel - Re: [PATCH v1 8/8] efi/dev-path-parser: Refactor _UID handling to use acpi_dev_uid_to

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Date:   Thu, 8 Sep 2022 10:20:47 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Hans de Goede <hdegoede@...hat.com>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-efi@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-spi@...r.kernel.org,
        devel@...ica.org, "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>, Elie Morisse <syniurge@...il.com>,
        Nehal Shah <nehal-bakulchandra.shah@....com>,
        Shyam Sundar S K <shyam-sundar.s-k@....com>,
        Khalil Blaiech <kblaiech@...dia.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        Mark Brown <broonie@...nel.org>,
        Robert Moore <robert.moore@...el.com>,
        Wolfram Sang <wsa@...nel.org>
Subject: Re: [PATCH v1 8/8] efi/dev-path-parser: Refactor _UID handling to use acpi_dev_uid_to_integer()

On Wed, 7 Sept 2022 at 18:57, Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> ACPI utils provide acpi_dev_uid_to_integer() helper to extract _UID as
> an integer. Use it instead of custom approach.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/firmware/efi/dev-path-parser.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/firmware/efi/dev-path-parser.c b/drivers/firmware/efi/dev-path-parser.c
> index eb9c65f97841..113b3ca1bd76 100644
> --- a/drivers/firmware/efi/dev-path-parser.c
> +++ b/drivers/firmware/efi/dev-path-parser.c
> @@ -15,9 +15,11 @@
>  static long __init parse_acpi_path(const struct efi_dev_path *node,
>                                    struct device *parent, struct device **child)
>  {
> -       char hid[ACPI_ID_LEN], uid[11]; /* UINT_MAX + null byte */
>         struct acpi_device *adev;
>         struct device *phys_dev;
> +       char hid[ACPI_ID_LEN];
> +       long ret;
> +       u64 uid;
>
>         if (node->header.length != 12)
>                 return -EINVAL;
> @@ -27,12 +29,12 @@ static long __init parse_acpi_path(const struct efi_dev_path *node,
>                 'A' + ((node->acpi.hid >>  5) & 0x1f) - 1,
>                 'A' + ((node->acpi.hid >>  0) & 0x1f) - 1,
>                         node->acpi.hid >> 16);
> -       sprintf(uid, "%u", node->acpi.uid);
>
>         for_each_acpi_dev_match(adev, hid, NULL, -1) {
> -               if (adev->pnp.unique_id && !strcmp(adev->pnp.unique_id, uid))
> +               ret = acpi_dev_uid_to_integer(adev, &uid);
> +               if (ret == -ENODATA && node->acpi.uid == 0)
>                         break;
> -               if (!adev->pnp.unique_id && node->acpi.uid == 0)
> +               if (ret == 0 && node->acpi.uid == uid)

Is it necessary to reorder the conditions here? I.e., why not

> +               ret = acpi_dev_uid_to_integer(adev, &uid);
> +               if (ret == 0 && node->acpi.uid == uid)
>                         break;
> +               if (ret == -ENODATA && node->acpi.uid == 0)
>                         break;

?

With that fixed,

Reviewed-by: Ard Biesheuvel <ardb@...nel.org>