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

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Message-ID: <3DA4D57D-C7A1-484B-B7AE-3F1DB958F4C8@fb.com>
Date:   Tue, 9 Feb 2021 21:19:30 +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 11:57 AM, Joe Perches <joe@...ches.com> wrote:
> 
> On Tue, 2021-02-09 at 19:44 +0000, Song Liu wrote:
>>> 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:
> []
>>>> ---
>>>> 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
> 
> Looks right, you tell me though, this is the current -next file list
> for what is being suggested:
> 
> $ git ls-files | \
>  perl -n -e 'print $_ if ($_ =~ m@...ols/testing/selftests/bpf/progs/.*\.c$@ ||
>                $_ =~ m@...mples/bpf/.*_kern\.c$@ ||
>                $_ =~ m@...f/.*\.bpf\.c$@);'

Thanks! This looks great. 

Song

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