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From:   Song Liu <songliubraving@fb.com>
To:     Joe Perches <joe@perches.com>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
        Andy Whitcroft <apw@canonical.com>
Subject: Re: [PATCH v2] checkpatch: do not apply "initialise globals to 0"
 check to BPF progs
Thread-Topic: [PATCH v2] checkpatch: do not apply "initialise globals to 0"
 check to BPF progs
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Date:   Tue, 9 Feb 2021 18:24:42 +0000
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> On Feb 9, 2021, at 9:24 AM, Joe Perches <joe@perches.com> wrote:
>=20
> On Tue, 2021-02-09 at 09:00 -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:
>>=20
>>     ERROR: do not initialise globals to 0
>>     #19: FILE: samples/bpf/tracex1_kern.c:21:
>>=20
>> Cc: Andy Whitcroft <apw@canonical.com>
>> Cc: Joe Perches <joe@perches.com>
>> Signed-off-by: Song Liu <songliubraving@fb.com>
>>=20
>> ---
>> Changes v1 =3D> v2:
>>   1. Add function exclude_global_initialisers() to keep the code clean.
>=20
> thanks.  trivia and a question:
>=20
>> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
>> @@ -2428,6 +2428,15 @@ sub get_raw_comment {
>>  	return $comment;
>>  }
>>=20
>> +sub exclude_global_initialisers {
>> +	my ($realfile) =3D @_;
>> +
>> +	# Do not check for BPF programs (tools/testing/selftests/bpf/progs/*.c=
, samples/bpf/*_kern.c, *.bpf.c).
>> +	return $realfile =3D~ /^tools\/testing\/selftests\/bpf\/progs\/.*\.c/ =
||
>> +		$realfile =3D~ /^samples\/bpf\/.*_kern.c/ ||
>=20
> The checkpatch convention commonly used for $realfile comparisons
> to file patterns with directory paths is m@...@
>=20
> 	return $realfile =3D~ m@^tools/testing/selftests/bpf/progs/.*\.c@ ||
> 		$realfile =3D~ m@^samples/bpf/.*_kern\.c@ ||

Will fix.=20

>=20
>> +		$realfile =3D~ /.bpf.c$/;
>=20
> And lastly, is this pattern meant to escape the periods?
> I presume so, but if not, the leading period isn't useful.
>=20
> Maybe:
> 		$realfile =3D~ m@/bpf/.*\.bpf\.c$@;

Exactly! Will fix in v3.=20

Thanks,
Song

>=20
> $ git ls-files | grep "\.bpf\.c$"
> kernel/bpf/preload/iterators/iterators.bpf.c
> tools/bpf/bpftool/skeleton/pid_iter.bpf.c
> tools/bpf/bpftool/skeleton/profiler.bpf.c
> tools/bpf/runqslower/runqslower.bpf.c
>=20
> vs
>=20
> $ git ls-files | grep ".bpf.c$"
> drivers/net/hyperv/netvsc_bpf.c
> drivers/net/netdevsim/bpf.c
> kernel/bpf/preload/iterators/iterators.bpf.c
> lib/test_bpf.c
> net/core/lwt_bpf.c
> net/ipv4/tcp_bpf.c
> net/ipv4/udp_bpf.c
> net/netfilter/xt_bpf.c
> net/sched/act_bpf.c
> net/sched/cls_bpf.c
> samples/bpf/test_lwt_bpf.c
> tools/bpf/bpftool/skeleton/pid_iter.bpf.c
> tools/bpf/bpftool/skeleton/profiler.bpf.c
> tools/bpf/runqslower/runqslower.bpf.c
> tools/build/feature/test-bpf.c
> tools/build/feature/test-libbpf.c
> tools/lib/bpf/bpf.c
> tools/lib/bpf/libbpf.c
> tools/perf/tests/bpf.c
> tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
> tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c
> tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c
> tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c
> tools/testing/selftests/net/reuseport_bpf.c
> tools/testing/selftests/seccomp/seccomp_bpf.c
>=20
>=20