linux-kernel - Re: [PATCH v3] checkpatch: do not apply "initialise globals to 0" check to BPF progs

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Message-ID: <4D649CDF-A738-468E-AD00-8A64DDB11D1D@fb.com>
Date:   Tue, 9 Feb 2021 19:44:07 +0000
From:   Song Liu <songliubraving@...com>
To:     Joe Perches <joe@...ches.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        Andy Whitcroft <apw@...onical.com>
Subject: Re: [PATCH v3] checkpatch: do not apply "initialise globals to 0"
 check to BPF progs



> On Feb 9, 2021, at 10:59 AM, Joe Perches <joe@...ches.com> wrote:
> 
> On Tue, 2021-02-09 at 10:33 -0800, Song Liu wrote:
>> BPF programs explicitly initialise global variables to 0 to make sure
>> clang (v10 or older) do not put the variables in the common section.
>> Skip "initialise globals to 0" check for BPF programs to elimiate error
>> messages like:
>> 
>>     ERROR: do not initialise globals to 0
>>     #19: FILE: samples/bpf/tracex1_kern.c:21:
>> 
>> Cc: Andy Whitcroft <apw@...onical.com>
>> Cc: Joe Perches <joe@...ches.com>
>> Signed-off-by: Song Liu <songliubraving@...com>
>> 
>> ---
>> Changes v2 => v3:
>>   1. Fix regex.
> 
> Unfortunately, this has broken regexes...
> 
>> Changes v1 => v2:
>>   1. Add function exclude_global_initialisers() to keep the code clean.
>> ---
>>  scripts/checkpatch.pl | 12 +++++++++++-
>>  1 file changed, 11 insertions(+), 1 deletion(-)
>> 
>> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
>> @@ -2428,6 +2428,15 @@ sub get_raw_comment {
>>  	return $comment;
>>  }
>>  
>> +sub exclude_global_initialisers {
>> +	my ($realfile) = @_;
>> +
>> +	# Do not check for BPF programs (tools/testing/selftests/bpf/progs/*.c, samples/bpf/*_kern.c, *.bpf.c).
>> +	return $realfile =~ m@...ools\/testing\/selftests\/bpf\/progs\/.*\.c@ ||
> 
> You don't need to escape the / when using m@@, and this doesn't work
> given the leading / after @, and it should use a trailing $
> 
> 	return $realfile =~ m@...ols/testing/selftests/bpf/progs/.*\.c$@ ||
> 
>> +		$realfile =~ m@...mples\/bpf\/.*_kern.c@ ||
> 
> This is still missing an escape on the . before c@, and there's no
> trailing $ between c and @
> 
> 		$realfile =~ m@...mples/bpf/.*_kern\.c$@ ||
> 
>> +		$realfile =~ m@...f/.*\.bpf\.c$@;
> 
> I believe I showed the correct regexes in my earlier reply.

Just to be sure I got everything correct, does the follow look right?

        return $realfile =~ m@...ols/testing/selftests/bpf/progs/.*\.c$@ ||
                $realfile =~ m@...mples/bpf/.*_kern\.c$@ ||
                $realfile =~ m@...f/.*\.bpf\.c$@;

Thanks,
Song