On 9/24/21 1:23 PM, Kees Cook wrote:
While discussing how to format the addition of various function
attributes, some "unwritten rules" of ordering surfaced[1]. Capture a
synthesized version of Linus's, Joe's, and Rasmus's recommendations on
this subject for future reference.
[1] https://lore.kernel.org/mm-commits/CAHk-=wiOCLRny5aifWNhr621kYrJwhfURsa0vFPeUEm8mF0ufg@xxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
Documentation/process/coding-style.rst | 27 ++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst
index 42969ab37b34..3559c34a9281 100644
--- a/Documentation/process/coding-style.rst
+++ b/Documentation/process/coding-style.rst
@@ -487,6 +487,33 @@ 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 prototype, please keep the `order of elements regular
+<https://lore.kernel.org/mm-commits/CAHk-=wiOCLRny5aifWNhr621kYrJwhfURsa0vFPeUEm8mF0ufg@xxxxxxxxxxxxxx>`_. For example::
+
+ __must_check __printf(4, 5) __malloc __init
+ static __always_inline void *action(enum magic value, size_t size,
+ u8 count, char *fmt, ...)
+ {
+ ...
+ }
+
+The preferred order of elements for a function prototype is:
+
+- attributes on the preceding lines
+
I thought that idea was already nacked: (it's more of a BSD thing AFAIK)
(and I would NAK it if I could :)
"""
Attributes should be on their own line, they can be quite lengthy.
No, no no. They really shouldn't.
""
from: https://lore.kernel.org/mm-commits/CAHk-=wjS-Jg7sGMwUPpDsjv392nDOOs0CtUtVkp=S6Q7JzFJRw@xxxxxxxxxxxxxx/
+ - return type attributes (here, ``__must_check``)
+ - function parameter attributes (here, ``__printf(4,5)``)
+ - function behavior attributes (here, ``__malloc``)
+ - storage class attributes (here, ``__init``)
+
+- main function prototype on the next lines
+
+ - storage class (here, ``static __always_inline`` -- even though
+ ``__always_inline`` is technically an attribute, it is treated like
+ ``inline``)
+ - return type (here, ``void *``)
+ - function name (here, ``action``)
+ - function parameters (as described earlier: each with type and name)
7) Centralized exiting of functions
-----------------------------------
--
~Randy
