linux-kernel - Re: [PATCH v2] ACPI: LPSS: use acpi_dev_uid_match() for matching

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Message-ID: <ZT+BiykmKepdAA8K@smile.fi.intel.com>
Date:   Mon, 30 Oct 2023 12:12:27 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Raag Jadav <raag.jadav@...el.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        len.brown@...el.com, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        mallikarjunappa.sangannavar@...el.com, bala.senthil@...el.com
Subject: Re: [PATCH v2] ACPI: LPSS: use acpi_dev_uid_match() for matching _UID

On Sat, Oct 28, 2023 at 11:58:12AM +0300, Raag Jadav wrote:
> On Fri, Oct 27, 2023 at 07:40:38PM +0200, Rafael J. Wysocki wrote:

...

> We'd probably end up with an oops trying to strcmp into a random address
> without knowing its type, so I think Mika's would be a better approach.
> 
> #define acpi_dev_uid_match(adev, uid2)                                                          \
> ({                                                                                              \
>         const char *uid1 = acpi_device_uid(adev);                                               \
>         u64 __uid1;                                                                             \
>                                                                                                 \
>         _Generic(uid2,                                                                          \
>                  int: uid1 && !kstrtou64(uid1, 0, &__uid1) && (typeof(uid2))__uid1 == uid2,     \
>                  const char *: uid1 && uid2 && !strcmp(uid1, (const char *)uid2),               \
>                  default: false);                                                               \
>                                                                                                 \
> })
> 
> This one I atleast got to compile, but I'm not very well versed with _Generic,
> so this could definitely use some comments.

If you go this way, make _Generic() use simple in the macro with a help of two
additional functions (per type). Also you need to take care about uid2 type to
be _any_ unsigned integer. Or if you want to complicate things, then you need
to distinguish signed and unsigned cases.

P.S.
All to me it seems way too overengineered w/o any potential prospective user.

-- 
With Best Regards,
Andy Shevchenko