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 | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index c9de44a45778..b6580f25361d 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 +1355,27 @@ static int do_create(int argc, char **argv)
}
err = do_pin_fd(fd, pinfile);
- close(fd);
- if (err)
+ if (err) {
+ close(fd);
goto exit;
+ }
- 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));
+ close(fd);
+ goto exit;
+ }
+ close(fd);
+
+ if (json_output) {
+ jsonw_start_object(json_wtr);
+ jsonw_int_field(json_wtr, "id", map_info.id);
+ jsonw_end_object(json_wtr);
+ } else {
+ printf("Map successfully created with ID: %u\n", map_info.id);
+ }
exit:
if (attr.inner_map_fd > 0)
close(attr.inner_map_fd);
--
2.50.1
On 10/28/25 5:57 AM, Harshit Mogalapalli wrote:
> 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 | 24 ++++++++++++++++++++----
> 1 file changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
> index c9de44a45778..b6580f25361d 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 +1355,27 @@ static int do_create(int argc, char **argv)
> }
>
> err = do_pin_fd(fd, pinfile);
> - close(fd);
> - if (err)
> + if (err) {
> + close(fd);
I think you can remove close(fd) here,
> goto exit;
> + }
>
> - 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));
> + close(fd);
and here
> + goto exit;
> + }
>
> + close(fd);
and here,
> +
> + if (json_output) {
> + jsonw_start_object(json_wtr);
> + jsonw_int_field(json_wtr, "id", map_info.id);
> + jsonw_end_object(json_wtr);
> + } else {
> + printf("Map successfully created with ID: %u\n", map_info.id);
> + }
> exit:
and put close(fd) here.
> if (attr.inner_map_fd > 0)
> close(attr.inner_map_fd);
Hi Yonghong,
On 29/10/25 07:44, Yonghong Song wrote:
>
>
> On 10/28/25 5:57 AM, Harshit Mogalapalli wrote:
>> 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 | 24 ++++++++++++++++++++----
>> 1 file changed, 20 insertions(+), 4 deletions(-)
>>
>> diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
>> index c9de44a45778..b6580f25361d 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 +1355,27 @@ static int do_create(int argc, char **argv)
>> }
>> err = do_pin_fd(fd, pinfile);
>> - close(fd);
>> - if (err)
>> + if (err) {
>> + close(fd);
>
> I think you can remove close(fd) here,
>
>> goto exit;
>> + }
>> - 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));
>> + close(fd);
>
> and here
>
>> + goto exit;
>> + }
>> + close(fd);
>
> and here,
>
>> +
>> + if (json_output) {
>> + jsonw_start_object(json_wtr);
>> + jsonw_int_field(json_wtr, "id", map_info.id);
>> + jsonw_end_object(json_wtr);
>> + } else {
>> + printf("Map successfully created with ID: %u\n", map_info.id);
>> + }
>> exit:
>
> and put close(fd) here.
I think we need one more close_fd: label and then put a close(fd); here.
As there are other gotos to exit earlier in this function when fd is
uninitialized, which can the error like:
map.c: In function ‘do_create’:
map.c:1375:9: warning: ‘fd’ may be used uninitialized
[-Wmaybe-uninitialized]
1375 | close(fd);
| ^~~~~~~~~
map.c:1258:23: note: ‘fd’ was declared here
1258 | int err = -1, fd;
| ^~
So, maybe we could do something like this:
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));
+ 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);
+ } else {
+ printf("Map successfully created with ID: %u\n",
map_info.id);
+ }
+close_fd:
+ close(fd);
exit:
if (attr.inner_map_fd > 0)
close(attr.inner_map_fd);
I can prepare a v2 with this change, but wouldn't it be simpler to add a
direct close(fd); on the few error paths instead of introducing an
additional label for close(fd);?
Thoughts/Suggestions ?
Thanks,
Harshit
>
>> if (attr.inner_map_fd > 0)
>> close(attr.inner_map_fd);
>
>
On 10/29/25 9:05 AM, Harshit Mogalapalli wrote:
> Hi Yonghong,
>
>
> On 29/10/25 07:44, Yonghong Song wrote:
>>
>>
>> On 10/28/25 5:57 AM, Harshit Mogalapalli wrote:
>>> 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 | 24 ++++++++++++++++++++----
>>> 1 file changed, 20 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
>>> index c9de44a45778..b6580f25361d 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 +1355,27 @@ static int do_create(int argc, char **argv)
>>> }
>>> err = do_pin_fd(fd, pinfile);
>>> - close(fd);
>>> - if (err)
>>> + if (err) {
>>> + close(fd);
>>
>> I think you can remove close(fd) here,
>>
>>> goto exit;
>>> + }
>>> - 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));
>>> + close(fd);
>>
>> and here
>>
>>> + goto exit;
>>> + }
>>> + close(fd);
>>
>> and here,
>>
>>> +
>>> + if (json_output) {
>>> + jsonw_start_object(json_wtr);
>>> + jsonw_int_field(json_wtr, "id", map_info.id);
>>> + jsonw_end_object(json_wtr);
>>> + } else {
>>> + printf("Map successfully created with ID: %u\n", map_info.id);
>>> + }
>>> exit:
>>
>> and put close(fd) here.
>
> I think we need one more close_fd: label and then put a close(fd);
> here. As there are other gotos to exit earlier in this function when
> fd is uninitialized, which can the error like:
>
> map.c: In function ‘do_create’:
> map.c:1375:9: warning: ‘fd’ may be used uninitialized
> [-Wmaybe-uninitialized]
> 1375 | close(fd);
> | ^~~~~~~~~
> map.c:1258:23: note: ‘fd’ was declared here
> 1258 | int err = -1, fd;
> | ^~
>
>
>
> So, maybe we could do something like this:
>
> 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));
> + 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);
> + } else {
> + printf("Map successfully created with ID: %u\n",
> map_info.id);
> + }
> +close_fd:
> + close(fd);
> exit:
> if (attr.inner_map_fd > 0)
> close(attr.inner_map_fd);
>
> I can prepare a v2 with this change, but wouldn't it be simpler to add a
> direct close(fd); on the few error paths instead of introducing an
> additional label for close(fd);?
The above change LGTM. Thanks!
>
> Thoughts/Suggestions ?
>
> Thanks,
> Harshit
>
>>
>>> if (attr.inner_map_fd > 0)
>>> close(attr.inner_map_fd);
>>
>>
>
>
Hi Yonghong,
On 29/10/25 07:44, Yonghong Song wrote:
>
>
> On 10/28/25 5:57 AM, Harshit Mogalapalli wrote:
>> 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 | 24 ++++++++++++++++++++----
>> 1 file changed, 20 insertions(+), 4 deletions(-)
>>
>> diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
>> index c9de44a45778..b6580f25361d 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 +1355,27 @@ static int do_create(int argc, char **argv)
>> }
>> err = do_pin_fd(fd, pinfile);
>> - close(fd);
>> - if (err)
>> + if (err) {
>> + close(fd);
>
> I think you can remove close(fd) here,
>
>> goto exit;
>> + }
>> - 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));
>> + close(fd);
>
> and here
>
>> + goto exit;
>> + }
>> + close(fd);
>
> and here,
>
>> +
>> + if (json_output) {
>> + jsonw_start_object(json_wtr);
>> + jsonw_int_field(json_wtr, "id", map_info.id);
>> + jsonw_end_object(json_wtr);
>> + } else {
>> + printf("Map successfully created with ID: %u\n", map_info.id);
>> + }
>> exit:
>
> and put close(fd) here.
>
Thanks a lot for the suggestion.
Will do that and send a v2. Thanks for reviewing.
Regards,
Harshit
>> if (attr.inner_map_fd > 0)
>> close(attr.inner_map_fd);
>
>
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