On Mon, Aug 8, 2022 at 6:45 AM Quentin Monnet <quentin@xxxxxxxxxxxxx> wrote: > > On 08/08/2022 10:33, Hangbin Liu wrote: > > As discussed before[1], 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. > > > > Adding names for these maps could make users know what these maps used for. > > It also could make some tests (like test_offload.py, which skip base maps > > without names as a workaround) filter them out. > > > > As Quentin suggested, add a small wrapper to fall back with no name > > if kernel is not supported. > > > > [1] https://lore.kernel.org/bpf/CAEf4BzY66WPKQbDe74AKZ6nFtZjq5e+G3Ji2egcVytB9R6_sGQ@xxxxxxxxxxxxxx/ > > > > Suggested-by: Quentin Monnet <quentin@xxxxxxxxxxxxx> > > Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx> > > --- > > tools/lib/bpf/libbpf.c | 22 +++++++++++++++++++--- > > 1 file changed, 19 insertions(+), 3 deletions(-) > > > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > > index 77e3797cf75a..db4f1a02b9e0 100644 > > --- a/tools/lib/bpf/libbpf.c > > +++ b/tools/lib/bpf/libbpf.c > > @@ -4423,6 +4423,22 @@ static int probe_kern_prog_name(void) > > return probe_fd(ret); > > } > > > > +static int probe_kern_map_name(enum bpf_map_type map_type, > > + const char *map_name, __u32 key_size, > > + __u32 value_size, __u32 max_entries, > > + const struct bpf_map_create_opts *opts) > > +{ > > + int map; > > + > > + map = bpf_map_create(map_type, map_name, key_size, value_size, max_entries, opts); > > + if (map < 0 && errno == EINVAL) { > > + /* Retry without name */ > > + map = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, opts); > > + } > > + > > + return map; > > +} > > + > > static int probe_kern_global_data(void) > > { > > char *cp, errmsg[STRERR_BUFSIZE]; > > @@ -4434,7 +4450,7 @@ 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 = probe_kern_map_name(BPF_MAP_TYPE_ARRAY, "global_data", sizeof(int), 32, 1, NULL); > > Thanks! Some comments on the naming: It reads strange here to "probe" > for the maps, given that we still need to compare the return value > below. Maybe use something else instead of "probe_kern_map_name()"? > Maybe "map_create_adjust_name()" or "map_create_compat()" (or something > else)? > > Regarding "global_data": If the intent is to filter out these maps from > the output of bpftool for example, should we use a common prefix for the > three of them? "libbpf_" or "probe_"? Or even something shorter? I know > we're limited to 15 characters. Yeah, "libbpf_" sounds like the best name to let users know it's some libbpf-specific internal thing. It leaves only 8 characters for the "feature name", but we can be creative about those 8 symbols, right? :) > > Quentin
