Hi Quentin,

On 01/11/25 22:29, Quentin Monnet wrote:

2025-10-30 14:06 UTC-0700 ~ Harshit Mogalapalli harshit.m.mogalapalli@oracle.com

...

It is useful to print map ID on successful creation.

JSON case: $ ./bpftool -j map create /sys/fs/bpf/test_map4 type hash key 4 value 8 entries 128 name map4 {"id":12}

Generic case: $ ./bpftool map create /sys/fs/bpf/test_map5 type hash key 4 value 8 entries 128 name map5 Map successfully created with ID: 15

Bpftool Issue: https://github.com/libbpf/bpftool/issues/121 Signed-off-by: Harshit Mogalapalli harshit.m.mogalapalli@oracle.com

---

tools/bpf/bpftool/map.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c index c9de44a45778..80c96b33b553 100644 --- a/tools/bpf/bpftool/map.c +++ b/tools/bpf/bpftool/map.c @@ -1251,6 +1251,8 @@ static int do_create(int argc, char **argv) LIBBPF_OPTS(bpf_map_create_opts, attr); enum bpf_map_type map_type = BPF_MAP_TYPE_UNSPEC; __u32 key_size = 0, value_size = 0, max_entries = 0;

• struct bpf_map_info map_info = {};
• __u32 map_info_len = sizeof(map_info); const char *map_name = NULL; const char *pinfile; int err = -1, fd;

@@ -1353,13 +1355,24 @@ static int do_create(int argc, char **argv) } err = do_pin_fd(fd, pinfile);

• close(fd); if (err)

• goto exit;
  

• goto close_fd;
  

• if (json_output)

• jsonw_null(json_wtr);
  

• err = bpf_obj_get_info_by_fd(fd, &map_info, &map_info_len);
• if (err) {

• p_err("Failed to fetch map info: %s\n", strerror(errno));
  

Nit: Please remove the line break ('\n') here, p_err() already adds it.

Ah thanks for spotting that, will do.

...

• goto close_fd;
  

• }

• if (json_output) {

• jsonw_start_object(json_wtr);
  

• jsonw_int_field(json_wtr, "id", map_info.id);
  

• jsonw_end_object(json_wtr);
  

I've been wondering if we should have some parent object like '{"map_created": { "id": 15 }}' in case we later add more output, but I can't really see a good use case at the moment, I'm probably overthinking it... So I'm good with the current output. Thanks for this!

Thanks a lot for the review.

With the line break removed:

Sure will send a next version with updates to p_err and selftest(to not echo messages on success)

Reviewed-by: Quentin Monnet qmo@kernel.org

Regards, Harshit

2025-10-30 14:06 UTC-0700 ~ Harshit Mogalapalli harshit.m.mogalapalli@oracle.com

Add selftest to check if Map ID is printed on successful creation in both plain text and json formats.

Signed-off-by: Harshit Mogalapalli harshit.m.mogalapalli@oracle.com

.../testing/selftests/bpf/test_bpftool_map.sh | 36 +++++++++++++++++++ 1 file changed, 36 insertions(+)

diff --git a/tools/testing/selftests/bpf/test_bpftool_map.sh b/tools/testing/selftests/bpf/test_bpftool_map.sh index 515b1df0501e..013a64e96cbf 100755 --- a/tools/testing/selftests/bpf/test_bpftool_map.sh +++ b/tools/testing/selftests/bpf/test_bpftool_map.sh @@ -361,6 +361,40 @@ test_map_access_with_btf_list() { fi } +# Function to test map ID printing +# Parameters: +# $1: bpftool path +# $2: BPF_DIR +test_map_id_printing() {

• local bpftool_path="$1"
• local bpf_dir="$2"
• local test_map_name="test_map_id"
• local test_map_path="$bpf_dir/$test_map_name"
• local output
• output=$("$bpftool_path" map create "$test_map_path" type hash key 4 \

• value 8 entries 128 name "$test_map_name")
  

• if echo "$output" | grep -q "Map successfully created with ID:"; then

• echo "PASS: Map ID printed in plain text output."
  

• else

• echo "FAIL: Map ID not printed in plain text output."
  

• exit 1
  

Other tests in the file print a message only on failure, without a "FAIL:" prefix. Could you do the same, for consistency and brevity? Same for the JSON test.

Thanks, Quentin