On Wed, Aug 10, 2022 at 8:40 PM Hangbin Liu <liuhangbin@xxxxxxxxx> wrote:
>
> The bpftool self-created maps can appear in final map show output due to
> deferred removal in kernel. These maps don't have a name, which would make
> users confused about where it comes from.
>
> With a libbpf_ prefix name, users could know who created these maps.
> It also could make some tests (like test_offload.py, which skip base maps
> without names as a workaround) filter them out.
>
> Kernel adds bpf prog/map name support in the same merge
> commit fadad670a8ab ("Merge branch 'bpf-extend-info'"). So we can also use
> kernel_supports(NULL, FEAT_PROG_NAME) to check if kernel supports map name.
>
> As disscussed[1], Let's make bpf_map_create accept non-null
> name string, and silently ignore the name if kernel doesn't support.
>
> [1] https://lore.kernel.org/bpf/CAEf4BzYL1TQwo1231s83pjTdFPk9XWWhfZC5=KzkU-VO0k=0Ug@xxxxxxxxxxxxxx/
>
> Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
> ---
> v3: let bpf_map_create ignore the name if kernel doesn't support
> v2: rename the wrapper with proper name
> ---
Applied to bpf-next. But let's also do the same for bpf_prog_load().
We can make probe_kern_prog_name() use sys_bpf_prog_load() directly
and avoid calling bpf_prog_load() and thus avoiding circular
dependency.
Will you be able to do this change?
> tools/lib/bpf/bpf.c | 2 +-
> tools/lib/bpf/libbpf.c | 6 +++---
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index efcc06dafbd9..6a96e665dc5d 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -183,7 +183,7 @@ int bpf_map_create(enum bpf_map_type map_type,
> return libbpf_err(-EINVAL);
>
> attr.map_type = map_type;
> - if (map_name)
> + if (map_name && kernel_supports(NULL, FEAT_PROG_NAME))
> libbpf_strlcpy(attr.map_name, map_name, sizeof(attr.map_name));
> attr.key_size = key_size;
> attr.value_size = value_size;
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index f7364ea82ac1..a075211b3730 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -4432,7 +4432,7 @@ static int probe_kern_global_data(void)
> };
> int ret, map, insn_cnt = ARRAY_SIZE(insns);
>
> - map = bpf_map_create(BPF_MAP_TYPE_ARRAY, NULL, sizeof(int), 32, 1, NULL);
> + map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_global", sizeof(int), 32, 1, NULL);
> if (map < 0) {
> ret = -errno;
> cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
> @@ -4565,7 +4565,7 @@ static int probe_kern_array_mmap(void)
> LIBBPF_OPTS(bpf_map_create_opts, opts, .map_flags = BPF_F_MMAPABLE);
> int fd;
>
> - fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, NULL, sizeof(int), sizeof(int), 1, &opts);
> + fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_mmap", sizeof(int), sizeof(int), 1, &opts);
> return probe_fd(fd);
> }
>
> @@ -4612,7 +4612,7 @@ static int probe_prog_bind_map(void)
> };
> int ret, map, prog, insn_cnt = ARRAY_SIZE(insns);
>
> - map = bpf_map_create(BPF_MAP_TYPE_ARRAY, NULL, sizeof(int), 32, 1, NULL);
> + map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_det_bind", sizeof(int), 32, 1, NULL);
> if (map < 0) {
> ret = -errno;
> cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
> --
> 2.35.3
>
