From: Joe Perches <joe@perches.com>
To: Kees Cook <keescook@chromium.org>, Jonathan Corbet <corbet@lwn.net>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Randy Dunlap <rdunlap@infradead.org>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2] docs: Explain the desired position of function attributes
Date: Thu, 30 Sep 2021 18:16:53 -0700 [thread overview]
Message-ID: <d6472a0e635941de55b83ba2ec3e673a74a123b6.camel@perches.com> (raw)
In-Reply-To: <20210930192417.1332877-1-keescook@chromium.org>
On Thu, 2021-09-30 at 12:24 -0700, Kees Cook wrote:
> While discussing how to format the addition of various function
> attributes, some "unwritten rules" of ordering surfaced[1]. Capture as
> close as possible to Linus's preferences for future reference.
>
> (Though I note the dissent voiced by Joe Perches, Alexey Dobriyan, and
> others that would prefer all attributes live on a separate leading line.)
>
> [1] https://lore.kernel.org/mm-commits/CAHk-=wiOCLRny5aifWNhr621kYrJwhfURsa0vFPeUEm8mF0ufg@mail.gmail.com/
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> Documentation/process/coding-style.rst | 30 ++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst
> index 42969ab37b34..6b4feb1c71e7 100644
> --- a/Documentation/process/coding-style.rst
> +++ b/Documentation/process/coding-style.rst
> @@ -487,6 +487,36 @@ because it is a simple way to add valuable information for the reader.
> Do not use the ``extern`` keyword with function prototypes as this makes
> lines longer and isn't strictly necessary.
>
>
> +When writing a function declarations, please keep the `order of elements regular
> +<https://lore.kernel.org/mm-commits/CAHk-=wiOCLRny5aifWNhr621kYrJwhfURsa0vFPeUEm8mF0ufg@mail.gmail.com/>`_.
> +For example::
> +
> + extern __init void * __must_check void action(enum magic value, size_t size,
> + u8 count, char *fmt, ...) __printf(4, 5) __malloc;
> +
Read the paragraph above. extern should not be used in an example.
> +The preferred order of elements for a function prototype is:
> +
> +- storage class (here, ``extern``, and things like ``static __always_inline`` even though
> + ``__always_inline`` is technically an attribute, it is treated like ``inline``)
> +- storage class attributes (here, ``__init`` -- i.e. section declarations, but also things like ``__cold``)
> +- return type (here, ``void *``)
> +- return type attributes (here, ``__must_check``)
> +- function name (here, ``action``)
> +- function parameters (here, ``(enum magic value, size_t size, u8 count, char *fmt, ...)``, noting that parameter names should always be included)
> +- function parameter attributes (here, ``__printf(4, 5)``)
> +- function behavior attributes (here, ``__malloc``)
> +
> +Note that for a function definition (e.g. ``static inline``), the compiler does
> +not allow function parameter attributes after the function parameters. In these
> +cases, they should go after the storage class attributes (e.g. note the changed
> +position of ``__printf(4, 5)``)::
> +
> + static __always_inline __init __printf(4, 5) void * __must_check void action(
> + enum magic value, size_t size, u8 count, char *fmt, ...)
> + __malloc
> + {
> + ...
> + }
>
>
> 7) Centralized exiting of functions
> -----------------------------------
prev parent reply other threads:[~2021-10-01 1:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-30 19:24 [PATCH v2] docs: Explain the desired position of function attributes Kees Cook
2021-09-30 20:11 ` Randy Dunlap
2021-09-30 22:52 ` Kees Cook
2021-10-01 2:54 ` Joe Perches
2021-10-01 1:16 ` Joe Perches [this message]
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