On Thu, Sep 30, 2021 at 01:11:34PM -0700, Randy Dunlap wrote: > On 9/30/21 12:24 PM, 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, > > Drop that second "void" ? or what does it mean? > Can __must_check and void be used together? Gah, thanks. Fixed now in v3. > > > + u8 count, char *fmt, ...) __printf(4, 5) __malloc; > > + > > +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``) > > I'm not trying to get you to change this, but I would prefer to see > > extern __init __must_check void *action(...) <attributes>; > > i.e., with the return type adjacent to the function name. I have read and re-read Linus's emails, and did a frequency count in the kernel, and it looks like the preference is [return type] [return type attrs] but I personally agree with you. :) # regex I built from __must_check hits... $ re='((struct .*|void|char) \* ?|((unsigned )?(long|int)|bool|size_t)($| ))' # type before __must_check $ git grep -E "$re"'__must_check' | wc -l 746 # type after __must_check $ git grep -E '\b(static (__always_)?inline )?__must_check($| '"$re"')' | wc -l 297 # type split(!) across __must_check or otherwise weird... $ git grep -E '\b__must_check\b' | grep -Ev '\b(static (__always_)?inline )?__must_check($| '"$re"')' | grep -Ev "$re"'__must_check\b' | wc -l 44 -- Kees Cook
