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Subject: Re: [PATCH v3] checkpatch: do not apply "initialise globals to 0"
 check to BPF progs
From:   Joe Perches <joe@perches.com>
To:     Song Liu <songliubraving@fb.com>, linux-kernel@vger.kernel.org
Cc:     bpf@vger.kernel.org, Andy Whitcroft <apw@canonical.com>
Date:   Tue, 09 Feb 2021 10:59:30 -0800
In-Reply-To: <20210209183343.3929160-1-songliubraving@fb.com>
References: <20210209183343.3929160-1-songliubraving@fb.com>
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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@canonical.com>
> Cc: Joe Perches <joe@perches.com>
> Signed-off-by: Song Liu <songliubraving@fb.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@/^tools\/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 $realfile =~ m@^tools/testing/selftests/bpf/progs/.*\.c$@ ||

> +		$realfile =~ m@^samples\/bpf\/.*_kern.c@ ||

This is still missing an escape on the . before c@, and there's no
trailing $ between c and @

		$realfile =~ m@^samples/bpf/.*_kern\.c$@ ||

> +		$realfile =~ m@/bpf/.*\.bpf\.c$@;

I believe I showed the correct regexes in my earlier reply.