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From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Tue, 13 Apr 2021 08:17:09 -0700
Message-ID: <CAADnVQJmsipci_ou6OOFGC6O9z935jFw4+pe7YQvvh2=eCoarQ@mail.gmail.com>
Subject: Re: [PATCH] selftests/bpf: use !E instead of comparing with NULL
To:     Yang Li <yang.lee@linux.alibaba.com>
Cc:     Shuah Khan <shuah@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
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On Tue, Apr 13, 2021 at 2:52 AM Yang Li <yang.lee@linux.alibaba.com> wrote:
>
> Fix the following coccicheck warnings:
> ./tools/testing/selftests/bpf/progs/profiler.inc.h:189:7-11: WARNING
> comparing pointer to 0, suggest !E
> ./tools/testing/selftests/bpf/progs/profiler.inc.h:361:7-11: WARNING
> comparing pointer to 0, suggest !E
> ./tools/testing/selftests/bpf/progs/profiler.inc.h:386:14-18: WARNING
> comparing pointer to 0, suggest !E
> ./tools/testing/selftests/bpf/progs/profiler.inc.h:402:14-18: WARNING
> comparing pointer to 0, suggest !E
> ./tools/testing/selftests/bpf/progs/profiler.inc.h:433:7-11: WARNING
> comparing pointer to 0, suggest !E
> ./tools/testing/selftests/bpf/progs/profiler.inc.h:534:14-18: WARNING
> comparing pointer to 0, suggest !E
> ./tools/testing/selftests/bpf/progs/profiler.inc.h:625:7-11: WARNING
> comparing pointer to 0, suggest !E
> ./tools/testing/selftests/bpf/progs/profiler.inc.h:767:7-11: WARNING
> comparing pointer to 0, suggest !E
>
> Reported-by: Abaci Robot <abaci@linux.alibaba.com>
> Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
> ---
>  tools/testing/selftests/bpf/progs/profiler.inc.h | 22 +++++++++++-----------
>  1 file changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/progs/profiler.inc.h b/tools/testing/selftests/bpf/progs/profiler.inc.h
> index 4896fdf8..a33066c 100644
> --- a/tools/testing/selftests/bpf/progs/profiler.inc.h
> +++ b/tools/testing/selftests/bpf/progs/profiler.inc.h
> @@ -189,7 +189,7 @@ static INLINE void populate_ancestors(struct task_struct* task,
>  #endif
>         for (num_ancestors = 0; num_ancestors < MAX_ANCESTORS; num_ancestors++) {
>                 parent = BPF_CORE_READ(parent, real_parent);
> -               if (parent == NULL)
> +               if (!parent)

Sorry, but I'd like the progs to stay as close as possible to the way
they were written.
They might not adhere to kernel coding style in some cases.
The code could be grossly inefficient and even buggy.
Please don't run spell checks, coccicheck, checkpatch.pl on them.