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@xxxxxxxxxxxxxx/ > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > 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@xxxxxxxxxxxxxx/>`_. > +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 > -----------------------------------
