[PATCH bpf-next v9 5/5] bpftool: Show parameters of BPF task iterators.

Kui-Feng Lee
2022-08-31T02:38:42Z

Show tid or pid of iterators if giving an argument of tid or pid

For example, the command `bpftool link list` may list following
lines.

1: iter prog 2 target_name bpf_map
2: iter prog 3 target_name bpf_prog
33: iter prog 225 target_name task_file tid 1644
pids test_progs(1644)

Link 33 is a task_file iterator with tid 1644. For now, only targets
of task, task_file and task_vma may be with tid or pid to filter out
tasks other than those belonging to a process (pid) or a thread (tid).

Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Yonghong Song <yhs@fb.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 ef0dc2f8d5a2..2863639706dd 100644
--- a/tools/bpf/bpftool/link.c
+++ b/tools/bpf/bpftool/link.c
@@ -106,6 +106,13 @@ static const char *cgroup_order_string(__u32 order)
}
}

+static bool is_iter_task_target(const char *target_name)
+{
+ return strcmp(target_name, "task") == 0 ||
+ strcmp(target_name, "task_file") == 0 ||
+ strcmp(target_name, "task_vma") == 0;
+}
+
static void show_iter_json(struct bpf_link_info *info, json_writer_t *wtr)
{
const char *target_name = u64_to_ptr(info->iter.target_name);
@@ -114,6 +121,12 @@ static void show_iter_json(struct bpf_link_info *info, json_writer_t *wtr)

if (is_iter_map_target(target_name))
jsonw_uint_field(wtr, "map_id", info->iter.map.map_id);
+ else if (is_iter_task_target(target_name)) {
+ if (info->iter.task.tid)
+ jsonw_uint_field(wtr, "tid", info->iter.task.tid);
+ else if (info->iter.task.pid)
+ jsonw_uint_field(wtr, "pid", info->iter.task.pid);
+ }

if (is_iter_cgroup_target(target_name)) {
jsonw_lluint_field(wtr, "cgroup_id", info->iter.cgroup.cgroup_id);
@@ -237,6 +250,12 @@ static void show_iter_plain(struct bpf_link_info *info)

if (is_iter_map_target(target_name))
printf("map_id %u ", info->iter.map.map_id);
+ else if (is_iter_task_target(target_name)) {
+ if (info->iter.task.tid)
+ printf("tid %u ", info->iter.task.tid);
+ else if (info->iter.task.pid)
+ printf("pid %u ", info->iter.task.pid);
+ }

if (is_iter_cgroup_target(target_name)) {
printf("cgroup_id %llu ", info->iter.cgroup.cgroup_id);
--
2.30.2