linux-kernel - Re: [PATCH v1 1/1] bitops: Move aligned_byte

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Date: Tue, 7 May 2024 12:14:58 -0700
From: Yury Norov <yury.norov@...il.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org,
	Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: Re: [PATCH v1 1/1] bitops: Move aligned_byte_mask() to wordpart.h

On Tue, May 07, 2024 at 05:01:54PM +0300, Andy Shevchenko wrote:
> The bitops.h is for bit related operations. The aligned_byte_mask()
> is about byte (or part of the machine word) operations, for which
> we have a separate header, move the mentioned macro to wordpart.h
> to consolidate similar operations.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

Hi Andy,

I see the macro is used in lib/strnlen_user.c and in lib/usercopy.c.
In case of strnlen_user, the wordpart.h is included via linux/kernel.h,
which is OK to me. But In case of usercopy.c, I can't find how the
header is included. 

I'm sure there is some inclusion path, but it's always better to have
the dependencies listed explicitly.

Can you please send a 2nd version with the lib/usercopy.c including
wordpart.h?

Thanks,
Yury

> ---
>  include/linux/bitops.h   | 7 -------
>  include/linux/wordpart.h | 7 +++++++
>  2 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
> index 0b561ee6b4a4..ec45284c03f5 100644
> --- a/include/linux/bitops.h
> +++ b/include/linux/bitops.h
> @@ -8,13 +8,6 @@
>  
>  #include <uapi/linux/kernel.h>
>  
> -/* Set bits in the first 'n' bytes when loaded from memory */
> -#ifdef __LITTLE_ENDIAN
> -#  define aligned_byte_mask(n) ((1UL << 8*(n))-1)
> -#else
> -#  define aligned_byte_mask(n) (~0xffUL << (BITS_PER_LONG - 8 - 8*(n)))
> -#endif
> -
>  #define BITS_PER_TYPE(type)	(sizeof(type) * BITS_PER_BYTE)
>  #define BITS_TO_LONGS(nr)	__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
>  #define BITS_TO_U64(nr)		__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u64))
> diff --git a/include/linux/wordpart.h b/include/linux/wordpart.h
> index f6f8f83b15b0..4ca1ba66d2f0 100644
> --- a/include/linux/wordpart.h
> +++ b/include/linux/wordpart.h
> @@ -39,4 +39,11 @@
>   */
>  #define REPEAT_BYTE(x)	((~0ul / 0xff) * (x))
>  
> +/* Set bits in the first 'n' bytes when loaded from memory */
> +#ifdef __LITTLE_ENDIAN
> +#  define aligned_byte_mask(n) ((1UL << 8*(n))-1)
> +#else
> +#  define aligned_byte_mask(n) (~0xffUL << (BITS_PER_LONG - 8 - 8*(n)))
> +#endif
> +
>  #endif // _LINUX_WORDPART_H
> -- 
> 2.43.0.rc1.1336.g36b5255a03ac