Re: [PATCH v4 4/8] bits: introduce fixed-type BIT

Andy Shevchenko
2025-03-05T14:33:19Z

On Wed, Mar 05, 2025 at 10:00:16PM +0900, Vincent Mailhol via B4 Relay wrote:
> From: Lucas De Marchi <lucas.demarchi@intel.com>
>
> Implement fixed-type BIT to help drivers add stricter checks, like was

Here and in the Subject I would use BIT_Uxx().

> done for GENMASK().

...

> +/*
> + * Fixed-type variants of BIT(), with additional checks like GENMASK_t(). The

GENMASK_t() is not a well named macro.

> + * following examples generate compiler warnings due to shift-count-overflow:
> + *
> + * - BIT_U8(8)
> + * - BIT_U32(-1)
> + * - BIT_U32(40)
> + */
> +#define BIT_INPUT_CHECK(type, b) \
> + BUILD_BUG_ON_ZERO(const_true((b) >= BITS_PER_TYPE(type)))
> +
> +#define BIT_U8(b) (BIT_INPUT_CHECK(u8, b) + (unsigned int)BIT(b))
> +#define BIT_U16(b) (BIT_INPUT_CHECK(u16, b) + (unsigned int)BIT(b))

Why not u8 and u16? This inconsistency needs to be well justified.

> +#define BIT_U32(b) (BIT_INPUT_CHECK(u32, b) + (u32)BIT(b))
> +#define BIT_U64(b) (BIT_INPUT_CHECK(u64, b) + (u64)BIT_ULL(b))

Can you also use a TAB between the parentheses for better readability?
E.g.,

#define BIT_U64(b)r (BIT_INPUT_CHECK(u64, b) + (u64)BIT_ULL(b))

--
With Best Regards,
Andy Shevchenko