linux-kernel - Re: [PATCH v3] checkpatch: add fix option for ASSIGNMENT

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Date:   Sat, 21 Nov 2020 17:20:51 +0530
From:   Aditya <yashsri421@...il.com>
To:     Joe Perches <joe@...ches.com>
Cc:     linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-kernel@...r.kernel.org, lukas.bulwahn@...il.com
Subject: Re: [PATCH v3] checkpatch: add fix option for
 ASSIGNMENT_CONTINUATIONS

On 20/11/20 11:32 pm, Aditya wrote:
> On 20/11/20 10:56 pm, Joe Perches wrote:
>> On Fri, 2020-11-20 at 16:11 +0530, Aditya wrote:
>>> On 17/11/20 10:48 pm, Aditya Srivastava wrote:
>>>> Currently, checkpatch warns us if an assignment operator is placed
>>>> at the start of a line and not at the end of previous line.
>>>>
>>>> E.g., running checkpatch on commit 8195b1396ec8 ("hv_netvsc: fix
>>>> deadlock on hotplug") reports:
>>>>
>>>> CHECK: Assignment operator '=' should be on the previous line
>>>> +	struct netvsc_device *nvdev
>>>> +		= container_of(w, struct netvsc_device, subchan_work);
>>>>
>>>> Provide a simple fix by appending assignment operator to the previous
>>>> line and removing from the current line, if both the lines are additions
>>>> (ie start with '+')
>>>>
>>>> Signed-off-by: Aditya Srivastava <yashsri421@...il.com>
>>>> ---
>>>> Changes in v2:
>>>> add check if both the lines are additions (ie start with '+')
>>>>
>>>> Changes in v3:
>>>> quote $operator; test with division assignment operator ('/=')
>>>>
>>>>  scripts/checkpatch.pl | 10 ++++++++--
>>>>  1 file changed, 8 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
>>>> index c9aaaa443265..d5bc4d8e4f6c 100755
>>>> --- a/scripts/checkpatch.pl
>>>> +++ b/scripts/checkpatch.pl
>>>> @@ -3542,8 +3542,14 @@ sub process {
>>>>  
>>>>
>>>>  # check for assignments on the start of a line
>>>>  		if ($sline =~ /^\+\s+($Assignment)[^=]/) {
>>>> -			CHK("ASSIGNMENT_CONTINUATIONS",
>>>> -			    "Assignment operator '$1' should be on the previous line\n" . $hereprev);
>>>> +			my $operator = "$1";
>>>> +			if (CHK("ASSIGNMENT_CONTINUATIONS",
>>>> +				"Assignment operator '$1' should be on the previous line\n" . $hereprev) &&
>>>> +			    $fix && $prevrawline =~ /^\+/) {
>>>> +				# add assignment operator to the previous line, remove from current line
>>>> +				$fixed[$fixlinenr - 1] .= " $operator";
>>>> +				$fixed[$fixlinenr] =~ s/$operator\s*//;
>>>> +			}
>>>>  		}
>>>>  
>>>>
>>>>  # check for && or || at the start of a line
>>>>
>>>
>>> Hi Joe
>>> This patch probably got missed. Please review :)
>>
>> Did you look at $Assignment?  Did you see it can be /= ?
>>
> 
> Yes, I tested the patch with '/=' operator as well.
> As I could not find any occurrences in the past(over 4.13..5.8), I
> created an example for myself by modifying the above mentioned commit
> example i.e. commit 8195b1396ec8 ("hv_netvsc: fix deadlock on
> hotplug") as:
> 
> +	struct netvsc_device *nvdev
> +		/= container_of(w, struct netvsc_device, subchan_work);
> 
> [For Line 144 and 145(where the warning was reported for '=' earlier)]
> 
> The fix changes these lines to:
> +	struct netvsc_device *nvdev /=
> +		container_of(w, struct netvsc_device, subchan_work);
> 
> On retesting the patch with checkpatch.pl, it did not give this CHECK,
> nor did we add any new warning/error.
> 
>> If it is, what happens in the $fixed[$fixlinenr] line?
>>
> 
> In $fixed[$fixlinenr], we are just getting rid of the operator and any
> space(s) following it.
> 
> What do you think?
> 

I think I understood quoting incorrectly here. I had to use \Q.
I'll resend the modified patch with desired changes.
Sorry for inconvenience.

Thanks
Aditya