Re: [PATCH v2 1/2] stddef: Add offsetofend() variant of struct_offset()

[Alejandro Colomar <alx+linux-hardening@kernel.org>]

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Hi Bence,

> Date: 2026-11-12 10:29:33+0100
> From: Bence Csokas <bence.csokas@arm.com>
>
> Many call sites of offsetofend() use it for the purpose of pointer
> artihmetic. Thus, a common usage pattern is:
> 
>   offsetofend(typeof(*ptr), member)
> 
> Capturing this in one macro helps keep lines short and terse, while
> still making the purpose clear. It also helps discourage spelling out
> the type name on every callsite, leading to more maintainable code.
> 
> A similar struct_offset() macro already exists, so add an offsetof()
> variant in the same spirit.
> 
> Signed-off-by: Bence Csokas <bence.csokas@arm.com>
> ---
>  include/linux/overflow.h | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/include/linux/overflow.h b/include/linux/overflow.h
> index d0f04436343e..060dad4b6f3e 100644
> --- a/include/linux/overflow.h
> +++ b/include/linux/overflow.h
> @@ -464,6 +464,18 @@ static __always_inline size_t __must_check size_sub(size_t minuend, size_t subtr
>   */
>  #define struct_offset(p, member) (offsetof(typeof(*(p)), member))
>  
> +/**
> + * struct_offsetofend() - Calculate the end of a member within a struct
> + * @p: Pointer to the struct
> + * @member: Name of the member to get the end offset of
> + *
> + * Calculates the offset of the end of a particular @member of the structure
> + * pointed to by @p.
> + *
> + * Return: number of bytes to the location of @member.
> + */
> +#define struct_offsetofend(p, member) (offsetofend(typeof(*(p)), member))

The outer parentheses are unnecessary (they are unnecessary in
struct_offset() too, but that already exists).


Have a lovely day!
Alex

> +
>  /**
>   * __DEFINE_FLEX() - helper macro for DEFINE_FLEX() family.
>   * Enables caller macro to pass arbitrary trailing expressions
> 
> -- 
> 2.56.1
> 
> 

-- 
<https://www.alejandro-colomar.es>

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