linux-kernel - Re: [PATCH] checkpatch: Check for illegal return codes

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Message-ID: <f6498bb90c5da1ea1765412bd78071a7@codeaurora.org>
Date:   Tue, 03 Jul 2018 12:07:51 -0700
From:   pheragu@...eaurora.org
To:     Joe Perches <joe@...ches.com>
Cc:     apw@...onical.com, linux-kernel@...r.kernel.org,
        ckadabi@...eaurora.org, tsoni@...eaurora.org,
        bryanh@...eaurora.org, Patrick Pannuto <ppannuto@...eaurora.org>,
        Stepan Moskovchenko <stepanm@...eaurora.org>
Subject: Re: [PATCH] checkpatch: Check for illegal return codes

On 2018-07-03 11:19, Joe Perches wrote:
> On Tue, 2018-07-03 at 11:09 -0700, Prakruthi Deepak Heragu wrote:
>> The only legal integer return is 0, anything else
>> following "return" should be -ERRCODE or a function.
>> 
>> http://lkml.org/lkml/2010/7/23/318
>>   There's lots of "return -1;" statements in this patch - it's obscene
>>   that this is used to indicate "some error occurred" in kernel space
>>   rather than a real errno value - even when an existing function
>>   (eg, request_irq) gave you an error code already.
>> 
>> Signed-off-by: Patrick Pannuto <ppannuto@...eaurora.org>
>> Signed-off-by: Stepan Moskovchenko <stepanm@...eaurora.org>
>> Signed-off-by: Prakruthi Deepak Heragu <pheragu@...eaurora.org>
>> ---
>>  scripts/checkpatch.pl | 6 ++++++
>>  1 file changed, 6 insertions(+)
>> 
>> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
>> index a9c0550..260d252 100755
>> --- a/scripts/checkpatch.pl
>> +++ b/scripts/checkpatch.pl
>> @@ -6197,6 +6197,12 @@ sub process {
>>  			     "switch default: should use break\n" . $herectx);
>>  		}
>> 
>> +# check for return codes on error paths
>> +		if ($line =~ /\breturn\s+-\d+/) {
>> +			ERROR("NO_ERROR_CODE",
>> +			      "illegal return value, please use an error code");
>> +		}
>> +
> 
> Substitute illegal to invalid as this wouldn't be illegal.
> It might be invalid and this needs a newline and $herecurr
> 
> I'm not sure this is even useful.
> 
> There are _way_ too many of these already existing
> and simple return identifiers can be OK.
> 
> $ git grep -P '\breturn\s*\-(?!0)\d+' | wc -l
> 10193
> 
> and
> 
> $ git grep -P '\breturn\s*\-(?!1)\d+' | wc -l
> 240
True. However, this would be helpful to avoid usage of such return 
statements in the future.