A new link type, BPF_LINK_TYPE_STRUCT_OPS, was added to attach
struct_ops to links. (226bc6ae6405) It would be helpful for users to
know which map is associated with the link.
The assumption was that every link is associated with a BPF program, but
this does not hold true for struct_ops. It would be better to display
map_id instead of prog_id for struct_ops links. However, some tools may
rely on the old assumption and need a prog_id. The discussion on the
mailing list suggests that tools should parse JSON format. We will maintain
the existing JSON format by adding a map_id without removing prog_id. As
for plain text format, we will remove prog_id from the header line and add
a map_id for struct_ops links.
Signed-off-by: Kui-Feng Lee <kuifeng@xxxxxxxx>
Reviewed-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
---
tools/bpf/bpftool/link.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
index f985b79cca27..c79f2e8927d6 100644
--- a/tools/bpf/bpftool/link.c
+++ b/tools/bpf/bpftool/link.c
@@ -195,6 +195,10 @@ static int show_link_close_json(int fd, struct bpf_link_info *info)
info->netns.netns_ino);
show_link_attach_type_json(info->netns.attach_type, json_wtr);
break;
+ case BPF_LINK_TYPE_STRUCT_OPS:
+ jsonw_uint_field(json_wtr, "map_id",
+ info->struct_ops.map_id);
+ break;
default:
break;
}
@@ -227,7 +231,10 @@ static void show_link_header_plain(struct bpf_link_info *info)
else
printf("type %u ", info->type);
- printf("prog %u ", info->prog_id);
+ if (info->type == BPF_LINK_TYPE_STRUCT_OPS)
+ printf("map %u ", info->struct_ops.map_id);
+ else
+ printf("prog %u ", info->prog_id);
}
static void show_link_attach_type_plain(__u32 attach_type)
--
2.34.1
