Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> writes: > On Thu, Oct 31, 2019 at 10:37 AM Andrii Nakryiko > <andrii.nakryiko@xxxxxxxxx> wrote: >> >> On Tue, Oct 29, 2019 at 12:39 PM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote: >> > >> > From: Toke Høiland-Jørgensen <toke@xxxxxxxxxx> >> > >> > This adds support to libbpf for setting map pinning information as part of >> > the BTF map declaration, to get automatic map pinning (and reuse) on load. >> > The pinning type currently only supports a single PIN_BY_NAME mode, where >> > each map will be pinned by its name in a path that can be overridden, but >> > defaults to /sys/fs/bpf. >> > >> > Since auto-pinning only does something if any maps actually have a >> > 'pinning' BTF attribute set, we default the new option to enabled, on the >> > assumption that seamless pinning is what most callers want. >> > >> > When a map has a pin_path set at load time, libbpf will compare the map >> > pinned at that location (if any), and if the attributes match, will re-use >> > that map instead of creating a new one. If no existing map is found, the >> > newly created map will instead be pinned at the location. >> > >> > Programs wanting to customise the pinning can override the pinning paths >> > using bpf_map__set_pin_path() before calling bpf_object__load() (including >> > setting it to NULL to disable pinning of a particular map). >> > >> > Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx> >> > --- >> >> Please fix unconditional pin_path setting, with that: >> >> Acked-by: Andrii Nakryiko <andriin@xxxxxx> >> >> > tools/lib/bpf/bpf_helpers.h | 6 ++ >> > tools/lib/bpf/libbpf.c | 144 +++++++++++++++++++++++++++++++++++++++++-- >> > tools/lib/bpf/libbpf.h | 13 ++++ >> > 3 files changed, 154 insertions(+), 9 deletions(-) >> > >> > diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h >> > index 2203595f38c3..0c7d28292898 100644 >> > --- a/tools/lib/bpf/bpf_helpers.h >> > +++ b/tools/lib/bpf/bpf_helpers.h >> > @@ -38,4 +38,10 @@ struct bpf_map_def { >> > unsigned int map_flags; >> > }; >> > >> >> [...] >> >> > @@ -1270,6 +1292,28 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj, >> > } >> > map->def.value_size = sz; >> > map->btf_value_type_id = t->type; >> > + } else if (strcmp(name, "pinning") == 0) { >> > + __u32 val; >> > + int err; >> > + >> > + if (!get_map_field_int(map_name, obj->btf, def, m, >> > + &val)) >> > + return -EINVAL; >> > + pr_debug("map '%s': found pinning = %u.\n", >> > + map_name, val); >> > + >> > + if (val != LIBBPF_PIN_NONE && >> > + val != LIBBPF_PIN_BY_NAME) { >> > + pr_warn("map '%s': invalid pinning value %u.\n", >> > + map_name, val); >> > + return -EINVAL; >> > + } >> > + err = build_map_pin_path(map, pin_root_path); >> >> uhm... only if (val == LIBBPF_PIN_BY_NAME)?.. maybe extend tests with >> a mix if auto-pinned and never pinned map to catch issue like this? > > I was wondering why your selftest didn't catch this, got puzzled for a > bit. It's because this code path will be executed only when map > defintion has __uint(pinning, LIBBPF_PIN_NONE), can you please add > that to selftest as well? Can do :) -Toke