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Subject: Re: [PATCH] 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:   Mon, 08 Feb 2021 22:31:19 -0800
In-Reply-To: <20210208234002.3294265-1-songliubraving@fb.com>
References: <20210208234002.3294265-1-songliubraving@fb.com>
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On Mon, 2021-02-08 at 15:40 -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:

Another possible option is simply to add --ignore=GLOBAL_INITIALISERS
to the checkpatch command line for these files.

> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -4323,7 +4323,11 @@ sub process {
> ?		}
> ?
> 
> ?# check for global initialisers.
> -		if ($line =~ /^\+$Type\s*$Ident(?:\s+$Modifier)*\s*=\s*($zero_initializer)\s*;/) {
> +# Do not apply to BPF programs (tools/testing/selftests/bpf/progs/*.c, samples/bpf/*_kern.c, *.bpf.c).
> +		if ($line =~ /^\+$Type\s*$Ident(?:\s+$Modifier)*\s*=\s*($zero_initializer)\s*;/ &&
> +		    $realfile !~ /^tools\/testing\/selftests\/bpf\/progs\/.*\.c/ &&
> +		    $realfile !~ /^samples\/bpf\/.*_kern.c/ &&
> +		    $realfile !~ /.bpf.c$/) {
> ?			if (ERROR("GLOBAL_INITIALISERS",
> ?				  "do not initialise globals to $1\n" . $herecurr) &&
> ?			    $fix) {