linux-kernel - Re: [PATCH v1] checkpatch: test missing initial blank line in block comment

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Date:   Fri, 7 Apr 2017 09:56:31 +0000
From:   Hugues FRUCHET <hugues.fruchet@...com>
To:     Joe Perches <joe@...ches.com>, Andy Whitcroft <apw@...onical.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] checkpatch: test missing initial blank line in block
 comment

Hi Joe,

here is the output with the last version of the script: 
https://paste.ubuntu.com/24333124/

Differences are on the macro cases and the //foo \ *bar, no more warned.

BR,
Hugues.

On 04/05/2017 03:26 PM, Hugues Fruchet wrote:
>
>
> On 04/05/2017 11:55 AM, Joe Perches wrote:
>> On Wed, 2017-04-05 at 09:43 +0000, Hugues FRUCHET wrote:
>>>
>>> On 04/05/2017 10:35 AM, Joe Perches wrote:
>>>> On Wed, 2017-04-05 at 08:23 +0000, Hugues FRUCHET wrote:
>>>>> Hi Joe, thanks for reviewing,
>>>>
>>>> Hello Hugues
>>>>
>>>>> I have run the command you advice on the entire kernel code, modifying
>>>>> the script to only match the newly introduced check case.
>>>>> There was 14389 hits, quite huge, so I cannot 100% certify that there
>>>>> are no false positives, but I have checked the output carefully and
>>>>> found 2 limit cases:
>>>>>
>>>>> 1) space character placed just after "/*"
>>>>> WARNING: Block comments starts with an empty /*
>>>>> #330: FILE: arch/alpha/kernel/core_irongate.c:330:
>>>>> +    /*
>>>>> +     * Check for within the AGP aperture...
>>>>> => 146 hits (grep -c -n -E "\/\* $" /tmp/check.txt)
>>>>>
>>>>> 2) // style comment followed by pointer dereference
>>>>> WARNING: Block comments starts with an empty /*
>>>>> #426: FILE: drivers/media/dvb-core/dvb_ca_en50221.c:426:
>>>>> +    // success
>>>>> +    *tupleType = _tupleType;
>>>>> => 4 hits
>>>>>
>>>>> Anyway this reveal comment style related issues, so I would say
>>>>> that we
>>>>> can keep script as it is, what do you think about ?
>>>>
>>>> Glancing at the output, there is also the comment
>>>> in a multiline macro case:
>>>>
>>>> WARNING: Block comments starts with an empty /*
>>>> #354: FILE: arch/mips/include/asm/processor.h:354:
>>>> +    /*                            \
>>>> +     * Other stuff associated with the process        \
>>>>
>>>> Dunno how common that is, but maybe the test
>>>> should be changed to avoid those.
>>>>
>>>
>>> Here is a proposal that remove this macro case:Per
>>>
>>> # Missing initial /*
>>> if ($realfile !~ m@^(drivers/net/|net/)@ &&    #networking exception
>>>      $prevrawline =~ /^\+[ \t]\/\**.+[ \t]/ &&    #start with /*...
>>>      $prevrawline !~ /^\+.*\/\*.*\*\/[ \t]*/ &&    #no inline /*...*/
>>> +   $prevrawline !~ /^\+[ \t]\/\*+[ \t]+\\$/ &&#no macro /*<tab><\>
>>>      $rawline =~ /^\+[ \t]*\*/ &&
>>>      $realline > 2) {
>>
>> Perhaps it's better to change this to
>>
>>     $prevrawline !~ /^\+\s*\/\*.*\\$/
>
> KO with this line, I suspect you meant "\s" instead of "." in above
> expression, so I've changed to:
>        $prevrawline !~ /^\+\s*\/\*\s*\\$/
> this one is OK
>
>>
>> Also perhaps the
>>     // foo
>>     *bar = baz;
>>
>> case could be avoided by adding tests for the
>> comment character $; on $prevline and $line
>> and not looking only at $prevrawline and $rawline.
>>
>
> Sorry for my poor understanding of the script but I don't catch what you
> meant regarding "raw" and non "raw" variables, so I've done the job
> simply by excluding the lines starting with "//":
>       $prevrawline !~ /^\+.*\/\/.*[ \t]*/ &&    #no inline //
>
> Which gives finally:
>
> # Missing initial /*
> if ($realfile !~ m@^(drivers/net/|net/)@ &&    #networking exception
>   $prevrawline =~ /^\+[ \t]\/\**.+[ \t]/ &&    #start with /*...
>   $prevrawline !~ /^\+.*\/\*.*\*\/[ \t]*/ &&    #no inline /*...*/
> + $prevrawline !~ /^\+.*\/\/.*[ \t]*/ &&    #no inline //
> + $prevrawline !~ /^\+\s*\/\*\s*\\$/ &&    #no macro /*<whitespace><\>
>   $rawline =~ /^\+[ \t]*\*/ &&
>   $realline > 2) {
>      WARN("MISSING_INITIAL_BLOCK_COMMENT_STYLE",
>           "Block comments starts with an empty /*\n" . $hereprev);
>     }
>
>
> BR,
> Hugues.