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

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Date: Thu, 11 Apr 2024 13:14:04 +0200
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Przemek Kitszel <przemyslaw.kitszel@...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

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?

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

Thanks!
Olek