[RFC] docs: Define c_paren_attributes for attributes with arguments

[RFC] docs: Define c_paren_attributes for attributes with arguments

[Kees Cook]

While Sphinx's "c_id_attributes" is needed for basic attributes, any
attributes with arguments need to be defined in "c_paren_attributes"
to avoid errors like:

include/linux/fortify-string.h:116: warning: Function parameter or member '__builtin_strncpy' not described in '__diagnose_as'
include/linux/fortify-string.h:116: warning: Function parameter or member '1' not described in '__diagnose_as'
include/linux/fortify-string.h:116: warning: Function parameter or member '2' not described in '__diagnose_as'
include/linux/fortify-string.h:116: warning: Function parameter or member '3' not described in '__diagnose_as'

Move such attributes to "c_paren_attributes" and add __alloc_size
and __diagnose_as to the list.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
This patch is a lie (the above warning is actually not fixed), but I
was hoping someone could help with this. The Sphinx documentation says:

c_paren_attributes
  A list of strings that the parser additionally should accept as
  attributes with one argument. That is, if my_align_as is in the list,
  then my_align_as(X) is parsed as an attribute for all strings X that
  have balanced braces ((), [], and {}). This can for example be used
  when attributes have been #define d for portability.

However, this appears to only work for attributes with literally a single
argument not "all strings X", so things like __printf and __diagnose_as
don't work.

Does this need fixing in Sphinx? Or am I missing something?
---
 Documentation/conf.py | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/Documentation/conf.py b/Documentation/conf.py
index 934727e23e0e..17f996e3709f 100644
--- a/Documentation/conf.py
+++ b/Documentation/conf.py
@@ -59,18 +59,14 @@ if major >= 3:
 
             # include/linux/compiler_attributes.h:
             "__alias",
-            "__aligned",
             "__aligned_largest",
             "__always_inline",
-            "__assume_aligned",
             "__cold",
             "__attribute_const__",
             "__copy",
             "__pure",
             "__designated_init",
             "__visible",
-            "__printf",
-            "__scanf",
             "__gnu_inline",
             "__malloc",
             "__mode",
@@ -80,7 +76,6 @@ if major >= 3:
             "__noreturn",
             "__packed",
             "__pure",
-            "__section",
             "__always_unused",
             "__maybe_unused",
             "__used",
@@ -97,6 +92,21 @@ if major >= 3:
 
             # include/linux/linkage.h:
             "asmlinkage",
+
+            # include/linux/fortify-string.h:
+            "__FORTIFY_INLINE",
+        ]
+
+        # Same as c_id_attributes above, but for those with arguments.
+        c_paren_attributes = [
+            # include/linux/compiler_attributes.h:
+            "__aligned",
+            "__alloc_size",
+            "__assume_aligned",
+            "__diagnose_as",
+            "__printf",
+            "__scanf",
+            "__section",
         ]
 
 else:
-- 
2.34.1

Re: [RFC] docs: Define c_paren_attributes for attributes with arguments

[Akira Yokosawa]

Hi Kees,

I expected some responses from Jon, but looks like he's been busy
elsewhere. Let me chime in.

On Fri,  2 Sep 2022 15:35:07 -0700, Kees Cook wrote:
> While Sphinx's "c_id_attributes" is needed for basic attributes, any
> attributes with arguments need to be defined in "c_paren_attributes"
> to avoid errors like:
> 
> include/linux/fortify-string.h:116: warning: Function parameter or member '__builtin_strncpy' not described in '__diagnose_as'
> include/linux/fortify-string.h:116: warning: Function parameter or member '1' not described in '__diagnose_as'
> include/linux/fortify-string.h:116: warning: Function parameter or member '2' not described in '__diagnose_as'
> include/linux/fortify-string.h:116: warning: Function parameter or member '3' not described in '__diagnose_as'

These warnings are from ./scripts/kernel-doc.
So I think you need to teach the script about "__diagnose_as" so that
the kernel-doc comment of strncpy() can be converted to reST doc
which Sphinx can understand.

Past changes in ./scripts/kernel-doc might give you some hints.

That said, I think Jon should be able to provide a pin-point suggestion.

HTH,

        Thanks, akira

> 
> Move such attributes to "c_paren_attributes" and add __alloc_size
> and __diagnose_as to the list.> 
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: linux-doc@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> This patch is a lie (the above warning is actually not fixed), but I
> was hoping someone could help with this. The Sphinx documentation says:> 
> c_paren_attributes
>   A list of strings that the parser additionally should accept as
>   attributes with one argument. That is, if my_align_as is in the list,
>   then my_align_as(X) is parsed as an attribute for all strings X that
>   have balanced braces ((), [], and {}). This can for example be used
>   when attributes have been #define d for portability.
> 
> However, this appears to only work for attributes with literally a single
> argument not "all strings X", so things like __printf and __diagnose_as
> don't work.
> 
> Does this need fixing in Sphinx? Or am I missing something?
> ---
>  Documentation/conf.py | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/conf.py b/Documentation/conf.py
> index 934727e23e0e..17f996e3709f 100644
> --- a/Documentation/conf.py
> +++ b/Documentation/conf.py
> @@ -59,18 +59,14 @@ if major >= 3:
>  
>              # include/linux/compiler_attributes.h:
>              "__alias",
> -            "__aligned",
>              "__aligned_largest",
>              "__always_inline",
> -            "__assume_aligned",
>              "__cold",
>              "__attribute_const__",
>              "__copy",
>              "__pure",
>              "__designated_init",
>              "__visible",
> -            "__printf",
> -            "__scanf",
>              "__gnu_inline",
>              "__malloc",
>              "__mode",
> @@ -80,7 +76,6 @@ if major >= 3:
>              "__noreturn",
>              "__packed",
>              "__pure",
> -            "__section",
>              "__always_unused",
>              "__maybe_unused",
>              "__used",
> @@ -97,6 +92,21 @@ if major >= 3:
>  
>              # include/linux/linkage.h:
>              "asmlinkage",
> +
> +            # include/linux/fortify-string.h:
> +            "__FORTIFY_INLINE",
> +        ]
> +
> +        # Same as c_id_attributes above, but for those with arguments.
> +        c_paren_attributes = [
> +            # include/linux/compiler_attributes.h:
> +            "__aligned",
> +            "__alloc_size",
> +            "__assume_aligned",
> +            "__diagnose_as",
> +            "__printf",
> +            "__scanf",
> +            "__section",
>          ]
>  
>  else:
> -- 
> 2.34.1

Re: [RFC] docs: Define c_paren_attributes for attributes with arguments

[Kees Cook]

On Fri, Sep 09, 2022 at 02:08:30PM +0900, Akira Yokosawa wrote:
> Hi Kees,
> 
> I expected some responses from Jon, but looks like he's been busy
> elsewhere. Let me chime in.
> 
> On Fri,  2 Sep 2022 15:35:07 -0700, Kees Cook wrote:
> > While Sphinx's "c_id_attributes" is needed for basic attributes, any
> > attributes with arguments need to be defined in "c_paren_attributes"
> > to avoid errors like:
> > 
> > include/linux/fortify-string.h:116: warning: Function parameter or member '__builtin_strncpy' not described in '__diagnose_as'
> > include/linux/fortify-string.h:116: warning: Function parameter or member '1' not described in '__diagnose_as'
> > include/linux/fortify-string.h:116: warning: Function parameter or member '2' not described in '__diagnose_as'
> > include/linux/fortify-string.h:116: warning: Function parameter or member '3' not described in '__diagnose_as'
> 
> These warnings are from ./scripts/kernel-doc.
> So I think you need to teach the script about "__diagnose_as" so that
> the kernel-doc comment of strncpy() can be converted to reST doc
> which Sphinx can understand.

Ah! Thank you, yeah, I couldn't figure out where it was coming from.

> Past changes in ./scripts/kernel-doc might give you some hints.

Yeah, including changes from me for similar things. How quickly I
forgot! :)

Thanks,

-Kees

-- 
Kees Cook

Re: [RFC] docs: Define c_paren_attributes for attributes with arguments

[Jonathan Corbet]

Kees Cook <keescook@chromium.org> writes:

> While Sphinx's "c_id_attributes" is needed for basic attributes, any
> attributes with arguments need to be defined in "c_paren_attributes"
> to avoid errors like:
>
> include/linux/fortify-string.h:116: warning: Function parameter or member '__builtin_strncpy' not described in '__diagnose_as'
> include/linux/fortify-string.h:116: warning: Function parameter or member '1' not described in '__diagnose_as'
> include/linux/fortify-string.h:116: warning: Function parameter or member '2' not described in '__diagnose_as'
> include/linux/fortify-string.h:116: warning: Function parameter or member '3' not described in '__diagnose_as'
>
> Move such attributes to "c_paren_attributes" and add __alloc_size
> and __diagnose_as to the list.

So which tree are those warnings coming from?  I can't reproduce them
with linux-next.

As Akira noted, the kernel-doc script is the source of those warnings,
so changing the Sphinx configuration is unlikely to help.  I think we
just need to teach kernel-doc to ignore those attributes.

Thanks,

jon