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

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Date:   Tue, 09 Feb 2021 10:59:30 -0800
From:   Joe Perches <joe@...ches.com>
To:     Song Liu <songliubraving@...com>, linux-kernel@...r.kernel.org
Cc:     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 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.