netdev - Re: [PATCH] kernel-doc: fix struct_group

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Message-ID: <316aba6b-2384-4867-b634-89f9c07f03ca@intel.com>
Date: Thu, 11 Apr 2024 13:48:52 +0200
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: Alexander Lobakin <aleksander.lobakin@...el.com>
CC: Jonathan Corbet <corbet@....net>, Kees Cook <keescook@...omium.org>, Jakub
 Kicinski <kuba@...nel.org>, Dan Williams <dan.j.williams@...el.com>, "Gustavo
 A. R. Silva" <gustavoars@...nel.org>, Keith Packard <keithp@...thp.com>,
	<nex.sw.ncis.osdt.itp.upstreaming@...el.com>, <linux-doc@...r.kernel.org>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kernel-doc: fix struct_group_tagged() parsing

On 4/11/24 13:14, Alexander Lobakin wrote:
> From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
> Date: Thu, 11 Apr 2024 13:14:20 +0200
> 
>> On 4/11/24 11:32, Alexander Lobakin wrote:
>>> From: Kees Cook <keescook@...omium.org>
>>>
>>> kernel-doc emits a warning on struct_group_tagged() if you describe your
>>> struct group member:
>>>
>>> include/net/libeth/rx.h:69: warning: Excess struct member 'fp'
>>> description in 'libeth_fq'
>>>
>>> The code:
>>>
>>> /**
>>>    * struct libeth_fq - structure representing a buffer queue
>>>    * @fp: hotpath part of the structure
>>>    * @pp: &page_pool for buffer management
>>> [...]
>>>    */
>>> struct libeth_fq {
>>>      struct_group_tagged(libeth_fq_fp, fp,
>>>          struct page_pool    *pp;
>>> [...]
>>>      );
>>>
>>> When a struct_group_tagged() is encountered, we need to build a
>>> `struct TAG NAME;` from it, so that it will be treated as a valid
>>> embedded struct.
>>> Decouple the regex and do the replacement there. As far as I can see,
>>> this doesn't produce any new warnings on the current mainline tree.
>>>
>>> Reported-by: Jakub Kicinski <kuba@...nel.org>
>>> Closes: https://lore.kernel.org/netdev/20240405212513.0d189968@kernel.org
>>> Fixes: 50d7bd38c3aa ("stddef: Introduce struct_group() helper macro")
>>> Signed-off-by: Kees Cook <keescook@...omium.org>
>>> Co-developed-by: Alexander Lobakin <aleksander.lobakin@...el.com>
>>> Signed-off-by: Alexander Lobakin <aleksander.lobakin@...el.com>
>>> ---
>>>    scripts/kernel-doc | 3 ++-
>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/scripts/kernel-doc b/scripts/kernel-doc
>>> index 43a30f2de513..01ac8f794b30 100755
>>> --- a/scripts/kernel-doc
>>> +++ b/scripts/kernel-doc
>>> @@ -1152,7 +1152,8 @@ sub dump_struct($$) {
>>>            # - first eat non-declaration parameters and rewrite for
>>> final match
>>>            # - then remove macro, outer parens, and trailing semicolon
>>>            $members =~ s/\bstruct_group\s*\(([^,]*,)/STRUCT_GROUP(/gos;
>>> -        $members =~
>>> s/\bstruct_group_(attr|tagged)\s*\(([^,]*,){2}/STRUCT_GROUP(/gos;
>>> +        $members =~
>>> s/\bstruct_group_attr\s*\(([^,]*,){2}/STRUCT_GROUP(/gos;
>>> +        $members =~
>>> s/\bstruct_group_tagged\s*\(([^,]*),([^,]*),/struct $1 $2;
>>> STRUCT_GROUP(/gos;
>>>            $members =~
>>> s/\b__struct_group\s*\(([^,]*,){3}/STRUCT_GROUP(/gos;
>>>            $members =~
>>> s/\bSTRUCT_GROUP(\(((?:(?>[^)(]+)|(?1))*)\))[^;]*;/$2/gos;
>>>    
>>
>> I would complain on code that matches `[^,]*` part with 0 characters,
>> meaning no tag for struct_group_tagged(), or no attrs for
>> struct_group_attrs(). In such cases simpler struct_group() call should
>> be suggested. However, that issue was presented prior to your patch.
> 
> Rather a subject for checkpatch, not kernel-doc?

Good point.

But that reminds me that getting patches accepted into checkpatch is not
possible for mere mortals :/ (exaggerating here, but just a little)

> 
>>
>> This is clearly an improvement, so:
>> Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>
> 
> Thanks!
> Olek