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

On Thu, May 28, 2020 at 08:02 AM CEST, Andrii Nakryiko wrote:

On Wed, May 27, 2020 at 12:16 PM Jakub Sitnicki [off-list ref] wrote:

quoted

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.

quoted

        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