Re: [PATCH bpf-next 7/8] bpftool: Support link show for netns-attached links

[Jakub Sitnicki <jakub@cloudflare.com>]

On Thu, May 28, 2020 at 08:02 AM CEST, Andrii Nakryiko wrote:
> On Wed, May 27, 2020 at 12:16 PM Jakub Sitnicki <jakub@cloudflare.com> wrote:
>>
>> Make `bpf link show` aware of new link type, that is links attached to
>> netns. When listing netns-attached links, display netns inode number as its
>> identifier and link attach type.
>>
>> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
>> ---
>>  tools/bpf/bpftool/link.c | 19 +++++++++++++++++++
>>  1 file changed, 19 insertions(+)
>>
>> diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
>> index 670a561dc31b..83a17d62c4c3 100644
>> --- a/tools/bpf/bpftool/link.c
>> +++ b/tools/bpf/bpftool/link.c
>> @@ -17,6 +17,7 @@ static const char * const link_type_name[] = {
>>         [BPF_LINK_TYPE_TRACING]                 = "tracing",
>>         [BPF_LINK_TYPE_CGROUP]                  = "cgroup",
>>         [BPF_LINK_TYPE_ITER]                    = "iter",
>> +       [BPF_LINK_TYPE_NETNS]                   = "netns",
>>  };
>>
>>  static int link_parse_fd(int *argc, char ***argv)
>> @@ -122,6 +123,16 @@ static int show_link_close_json(int fd, struct bpf_link_info *info)
>>                         jsonw_uint_field(json_wtr, "attach_type",
>>                                          info->cgroup.attach_type);
>>                 break;
>> +       case BPF_LINK_TYPE_NETNS:
>> +               jsonw_uint_field(json_wtr, "netns_ino",
>> +                                info->netns.netns_ino);
>> +               if (info->netns.attach_type < ARRAY_SIZE(attach_type_name))
>> +                       jsonw_string_field(json_wtr, "attach_type",
>> +                               attach_type_name[info->netns.attach_type]);
>> +               else
>> +                       jsonw_uint_field(json_wtr, "attach_type",
>> +                                        info->netns.attach_type);
>> +               break;
>
> Can you please extract this attach_type handling into a helper func,
> it's annoying to read so many repetitive if/elses. Same for plain-text
> variant below. Thanks!

Looks easy enough. Will be done in v2.

>
>>         default:
>>                 break;
>>         }
>> @@ -190,6 +201,14 @@ static int show_link_close_plain(int fd, struct bpf_link_info *info)
>>                 else
>>                         printf("attach_type %u  ", info->cgroup.attach_type);
>>                 break;
>> +       case BPF_LINK_TYPE_NETNS:
>> +               printf("\n\tnetns_ino %u  ", info->netns.netns_ino);
>> +               if (info->netns.attach_type < ARRAY_SIZE(attach_type_name))
>> +                       printf("attach_type %s  ",
>> +                              attach_type_name[info->netns.attach_type]);
>> +               else
>> +                       printf("attach_type %u  ", info->netns.attach_type);
>> +               break;
>>         default:
>>                 break;
>>         }
>> --
>> 2.25.4
>>