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From:   Hao Luo <haoluo@google.com>
Date:   Tue, 30 Aug 2022 11:19:45 -0700
Message-ID: <CA+khW7hKHvOjz6WAB7ufTDbfe+AzJo9sJiXDVMKbWS6cnxC2Qw@mail.gmail.com>
Subject: Re: [PATCH bpf-next v1] bpftool: Add support for querying cgroup_iter link
To:     Martin KaFai Lau <kafai@fb.com>
Cc:     Quentin Monnet <quentin@isovalent.com>,
        linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
        Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        KP Singh <kpsingh@kernel.org>,
        John Fastabend <john.fastabend@gmail.com>,
        Stanislav Fomichev <sdf@google.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Yosry Ahmed <yosryahmed@google.com>
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On Tue, Aug 30, 2022 at 11:06 AM Martin KaFai Lau <kafai@fb.com> wrote:
>
> On Tue, Aug 30, 2022 at 02:33:47PM +0100, Quentin Monnet wrote:
> > > +static const char *cgroup_order_string(__u32 order)
> > > +{
> > > +   switch (order) {
> > > +   case BPF_CGROUP_ITER_ORDER_UNSPEC:
> > > +           return "order_unspec";
> > > +   case BPF_CGROUP_ITER_SELF_ONLY:
> > > +           return "self_only";
> > > +   case BPF_CGROUP_ITER_DESCENDANTS_PRE:
> > > +           return "descendants_pre";
> > > +   case BPF_CGROUP_ITER_DESCENDANTS_POST:
> > > +           return "descendants_post";
> > > +   case BPF_CGROUP_ITER_ANCESTORS_UP:
> > > +           return "ancestors_up";
> > > +   default: /* won't happen */
> > > +           return "";
> >
> > I wonder if that one should be "unknown", in case another option is
> > added in the future, so we can spot it and address it?
> I added "unknown" and applied.

Thanks Martin and Quentin, "unknown" is better than an empty string.