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From:   Jonathan Corbet <corbet@lwn.net>
To:     Aditya Srivastava <yashsri421@gmail.com>
Cc:     lukas.bulwahn@gmail.com,
        linux-kernel-mentees@lists.linuxfoundation.org,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] scripts: kernel-doc: add warning for comment not
 following kernel-doc syntax
In-Reply-To: <a35096d5-99e7-6b69-c959-1136d511a0ff@gmail.com>
References: <20210329092945.13152-1-yashsri421@gmail.com>
 <87czvit65m.fsf@meer.lwn.net>
 <a35096d5-99e7-6b69-c959-1136d511a0ff@gmail.com>
Date:   Wed, 31 Mar 2021 13:32:09 -0600
Message-ID: <87mtujktl2.fsf@meer.lwn.net>
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Aditya Srivastava <yashsri421@gmail.com> writes:

> On 29/3/21 7:26 pm, Jonathan Corbet wrote:
>> Aditya Srivastava <yashsri421@gmail.com> writes:
>> 
>>> Currently, kernel-doc start parsing the comment as a kernel-doc comment if
>>> it starts with '/**', but does not take into account if the content inside
>>> the comment too, adheres with the expected format.
>>> This results in unexpected and unclear warnings for the user.
>>>
>>> E.g., running scripts/kernel-doc -none mm/memcontrol.c emits:
>>> "mm/memcontrol.c:961: warning: expecting prototype for do not fallback to current(). Prototype was for get_mem_cgroup_from_current() instead"
>>>
>>> Here kernel-doc parses the corresponding comment as a kernel-doc comment
>>> and expects prototype for it in the next lines, and as a result causing
>>> this warning.
>>>
>>> Provide a clearer warning message to the users regarding the same, if the
>>> content inside the comment does not follow the kernel-doc expected format.
>>>
>>> Signed-off-by: Aditya Srivastava <yashsri421@gmail.com>
>>> ---
>>>  scripts/kernel-doc | 17 +++++++++++++----
>>>  1 file changed, 13 insertions(+), 4 deletions(-)
>> 
>> This is definitely a capability we want, but I really don't think that
>> we can turn it on by default - for now.  Experience shows that if you
>> create a blizzard of warnings, nobody sees any of them.  How many
>> warnings does this add to a full docs build?
>> 
>
> Hi Jonathan, here's the diff I have created for the warnings before
> and after the changes:
> https://github.com/AdityaSrivast/kernel-tasks/blob/master/random/kernel-doc/kernel_doc_comment_syntax.txt
>
> Around ~1320 new warnings of this type are added to the kernel tree,
> and around ~1580 warnings are removed.

So I finally got around to looking at this again...  How did you
generate that file?

I tried applying the patch and doing a normal full htmldocs build and
got all of four warnings:

  ./include/linux/seqlock.h:829: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
   * DEFINE_SEQLOCK(sl) - Define a statically allocated seqlock_t
  ./fs/jbd2/journal.c:1391: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
   *  journal_t * jbd2_journal_init_dev() - creates and initialises a journal structure
  ./fs/jbd2/journal.c:1422: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
   *  journal_t * jbd2_journal_init_inode () - creates a journal which maps to a inode.
  ./include/linux/dcache.h:309: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
   *      dget, dget_dlock -      get a reference to a dentry

Two observations:

 - This is not an awful lot of warnings - not the blizzard I had
   feared.  At this level, I think we can just merge the patch and
   then, hopefully, fix those cases.

 - All of the warned-about places are *attempts* to write real kerneldoc
   comments, they just got the syntax wrong in one way or another.  It's
   probably not worth the effort to try to detect this case - the
   warning is enough to draw attention to the comment in question.

Thanks,

jon