Commit 6f95de6d authored by Hao Luo's avatar Hao Luo Committed by Martin KaFai Lau
Browse files

bpftool: Add support for querying cgroup_iter link 



Support dumping info of a cgroup_iter link. This includes
showing the cgroup's id and the order for walking the cgroup
hierarchy. Example output is as follows:

> bpftool link show
1: iter  prog 2  target_name bpf_map
2: iter  prog 3  target_name bpf_prog
3: iter  prog 12  target_name cgroup  cgroup_id 72  order self_only

> bpftool -p link show
[{
        "id": 1,
        "type": "iter",
        "prog_id": 2,
        "target_name": "bpf_map"
    },{
        "id": 2,
        "type": "iter",
        "prog_id": 3,
        "target_name": "bpf_prog"
    },{
        "id": 3,
        "type": "iter",
        "prog_id": 12,
        "target_name": "cgroup",
        "cgroup_id": 72,
        "order": "self_only"
    }
]

Signed-off-by: default avatarHao Luo <haoluo@google.com>
Reviewed-by: default avatarQuentin Monnet <quentin@isovalent.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220829231828.1016835-1-haoluo@google.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@linux.dev>
parent 2eb68040

tools/bpf/bpftool/link.c

+35 −0
Original line number Diff line number Diff line
@@ -83,6 +83,29 @@ static bool is_iter_map_target(const char *target_name) 
	       strcmp(target_name, "bpf_sk_storage_map") == 0;

}



static bool is_iter_cgroup_target(const char *target_name)

{

	return strcmp(target_name, "cgroup") == 0;

}



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 "unknown";

	}

}



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);
@@ -91,6 +114,12 @@ 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);



	if (is_iter_cgroup_target(target_name)) {

		jsonw_lluint_field(wtr, "cgroup_id", info->iter.cgroup.cgroup_id);

		jsonw_string_field(wtr, "order",

				   cgroup_order_string(info->iter.cgroup.order));

	}

}



static int get_prog_info(int prog_id, struct bpf_prog_info *info)
@@ -208,6 +237,12 @@ 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);



	if (is_iter_cgroup_target(target_name)) {

		printf("cgroup_id %llu  ", info->iter.cgroup.cgroup_id);

		printf("order %s  ",

		       cgroup_order_string(info->iter.cgroup.order));

	}

}



static int show_link_close_plain(int fd, struct bpf_link_info *info)