linux-kernel - Re: [RFC PATCH] scripts: checkpatch.pl: remove obsolete in

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Message-ID: <4c2a4bfa-0e85-6385-58fd-af83349201e9@alibaba-inc.com>
Date:   Tue, 07 Nov 2017 00:08:21 +0800
From:   "Yang Shi" <yang.s@...baba-inc.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     apw@...onical.com, joe@...ches.com, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] scripts: checkpatch.pl: remove obsolete in_atomic
 rule



On 11/6/17 5:52 AM, Michal Hocko wrote:
> On Sat 04-11-17 03:08:06, Yang Shi wrote:
>> checkpatch.pl still reports the below in_atomic warning:
>>
>> WARNING: use of in_atomic() is incorrect outside core kernel code
>> +       if (in_atomic())
>>
>> But, in_atomic() has been used outside kernel dir for a long time, and
>> even drivers. So, remove the obsolete rule even though they can be
>> ignored.
> 
> NAK. in_atomic is tricky and shouldn't be used. I would bet most of the
> usage is simply broken. See more http://lkml.kernel.org/r/20171106100558.GD3165@worktop.lehotels.local

Thanks for following up. Yes, it sounds so. However, there is not a 
reliable and effective approach to check atomic context for both PREEMPT 
and !PREEMPT.

Yang

>   
>> Signed-off-by: Yang Shi <yang.s@...baba-inc.com>
>> CC: Andrew Morton <akpm@...ux-foundation.org>
>> ---
>> Not sure if removing the obsolete rule is preferred by checkpatch.pl, anyway
>> it sounds not make sense to keep invalid rule.
>>
>>   scripts/checkpatch.pl | 11 -----------
>>   1 file changed, 11 deletions(-)
>>
>> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
>> index 8b80bac..e8cf94f 100755
>> --- a/scripts/checkpatch.pl
>> +++ b/scripts/checkpatch.pl
>> @@ -6231,17 +6231,6 @@ sub process {
>>   			     "Using $1 should generally have parentheses around the comparison\n" . $herecurr);
>>   		}
>>   
>> -# whine mightly about in_atomic
>> -		if ($line =~ /\bin_atomic\s*\(/) {
>> -			if ($realfile =~ m@...ivers/@) {
>> -				ERROR("IN_ATOMIC",
>> -				      "do not use in_atomic in drivers\n" . $herecurr);
>> -			} elsif ($realfile !~ m@...rnel/@) {
>> -				WARN("IN_ATOMIC",
>> -				     "use of in_atomic() is incorrect outside core kernel code\n" . $herecurr);
>> -			}
>> -		}
>> -
>>   # whine about ACCESS_ONCE
>>   		if ($^V && $^V ge 5.10.0 &&
>>   		    $line =~ /\bACCESS_ONCE\s*$balanced_parens\s*(=(?!=))?\s*($FuncArg)?/) {
>> -- 
>> 1.8.3.1
>